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Mobile Communication and Mobile Computing Mobile Communication and Mobile Computing Prof. Dr. Alexander Schill TU Dresden, Computer Networks Dept. http://www.rn.inf.tu-dresden.de 1 Mobile Communication and Mobile Computing Contents 1. Motivation 2. Mobile Communication – – – – – – – History Principles Media Access Methods Mobile Radio Networks: Overview GSM HSCSD, GPRS UMTS 2 Mobile Communication and Mobile Computing Contents 2. Mobile Communication (Continuation) – Broadband-Radio Systems – Wireless Local-area Networks (IEEE 802.11, Bluetooth etc.) – Satellite-based Systems 3 Mobile Communication and Mobile Computing Contents 3. Mobile Computing – Layer 3 • MobileIP v4 & v6 • DHCP – Layer 4 – Higher Layers and Services • • • • • • WAP, XML Mobile RPC CODA, Databases Mobile Agents Middleware for spontaneous networking Services and system support for Mobile Computing 4 Mobile Communication and Mobile Computing 5 Literature Roth, J.: Mobile Computing, dpunkt-Verlag, 2002 Very good overview to mobile communication and mobile computing Schiller, J., Mobilkommunikation, Techniken für das allgegenwärtige Internet, Addison-Wesley, 2000 Mobile Communication principles and Mobile Computing Bernhard, Walke: Mobilfunknetze und ihre Protokolle, 2 Bände. Teubner, 2000 Principles, GSM, UMTS and other cellular Mobile Radio Networks [Vol.1] Circuit Switched Radio, Cordless Phone Systems, W-ATM, HIPERLAN, Satellite Radio, UPT [Vol.2] Schumny, Harald: Signalübertragung, Friedrich Vieweg & Sohn, Braunschweig/Wiesbaden 1987; Wave propagation and wireless transmission A.S. Tanenbaum: Computernetzwerke, 4. Aufl., Prentice Hall, 1998 Protocols, ISO/OSI, standards, fixed networks Principles Mobile Communication and Mobile Computing 1. Motivation and Examples 6 Mobile Communication and Mobile Computing 7 Motivation Speech- and Data Communication location independent and mobile New application areas, flexibility, improved workflows Requirements: - Mobile end-devices - Radio transmission - Localization and signalization/management - Standards - Application Concepts for mobile end-devices in distributed systems - Control of heterogeneous, dynamic infrastructures Mobile Computing Mobile Communication and Mobile Computing Application example: Civil Engineering, Field Service Large archives, Videoconferences Drafts, urgent modification ATM ISDN Building of enterprise A (main office) X.25 ISDN ATM Selected drafts, Videoconferences GSM Building of enterprise B Building of enterprise A (branch office) Construction supervisor Material data, status data, dates Architect GSM Building site 8 Mobile Communication and Mobile Computing WAP-Example: Order processing Order book • Status of bond transactions. • Executed and deleted orders are indicated in the order book for some days more. • Partial execution of some order is presented as one open and one executed partial order in the order book. • Details to an order could be indicated via dial-up of correspondent Links. 9 Mobile Communication and Mobile Computing Perspective: Mobile Multimedia Systems Local Resources, Error Protocols Product Data Main office Caching Maintenance technician Client LAN-Access Mobile Access - very different performance and charges: radio networks versus fixed networks Software-technical, automatic adaptation to concrete system environment Example: Access to picture data/compressed picture data/graphics/text 10 Mobile Communication and Mobile Computing Application Structure Ethernet Distributed Database Ethernet DB E-Fax-Order Branch office Firm xDSL Application GSM Ethernet Cache Resource Mobile Station Communication path Management DB-Access Distributed Database Client X 11 Mobile Communication and Mobile Computing 12 Traffic Telematics Systems Content Provider Main Office Content Provider ATM Internet Beam Radio, ISDN GSM Radio/Infrared DAB: Digital Audio Broadcast Infrastructure RDS/TMC: Radio Data System/ Traffic Message Channel Mobile Communication and Mobile Computing Mobile Communication Networks: Examples GSM (Global System for Mobile Communications): worldwide standard for digital, cellular Mobile Radio Networks UMTS (Universal Mobile Telecommunications System): European Standard for future digital Mobile Radio Networks AMPS (Advanced Mobile Phone System): analog Mobile Radio Networks in USA DECT (Digital Enhanced Cordless Telecommunications): European standard for cordless phones TETRA (Terrestrial Trunked Radio): European standard for circuit switched radio networks ERMES (European Radio Message System): European standard for radio paging systems (Pager) 802.11: International standard for Wireless Local Networks Bluetooth: wireless networking in close/local area Inmarsat: geostationary satellite systems Teledesic: planned satellite system on a non-geostationary orbit 13 Mobile Communication and Mobile Computing Mobile Communication: Development E (GSM1800) D (GSM900) C Mobile Phone Networks HSCSD EDGE GPRS Cordless Telephony CT2 DECT IMT2000/ UMTS Packet Networks Modacom Mobitex Circuit Switched Networks Satellite Networks Local Networks Tetra Iridium/ Globalstar Inmarsat Radio-LAN IEEE 802.11/ Hiperlan MBS IR-LAN 1990 1995 2000 2005 14 Mobile Communication and Mobile Computing Used Acronyms CT2: Cordless Telephone 2. Generation HSCSD: High Speed Circuit Switched Data GPRS: General Packet Radio Service EDGE: Enhanced Data Rates for GSM Evolution IMT2000: International Mobile Telecommunications by the year 2000 MBS: Mobile Broadband System 15 Mobile Communication and Mobile Computing 2. Mobile Communication 16 Mobile Communication and Mobile Computing Principles 17 Mobile Communication and Mobile Computing 18 Mobile Communication Tied to electro-magnetic radio transmission radio transmission orbital (satellite) terrestrial beam radio broadcast radio cellular equatorial orbit non-equatorial orbit non-cellular Principles: – Propagation and reception of electro-magnetic waves – Modulation methods and their properties – Multiplex methods – Satellite orbits/Sight- and overlap areas Mobile Communication and Mobile Computing Cellular Networks: Principles Channels 801-1600 Interference Zone R Channels 1-800 Channels 1-800 Supply- (radius R) and interference areas (5 R) 2 7 4 5 4 5 3 1 6 3 1 6 2 7 4 4 2 1 2 1 5 5 7 6 7 6 3 3 2 4 2 4 1 5 1 7 5 7 6 6 3 4 3 4 2 2 1 5 7-Cell-Cluster (repeat sample of the same radio-channels) 19 Mobile Communication and Mobile Computing Cellular Networks: Principles Cell structure: Example Reference cell Cell in the interference area of the reference cell Further cells, whose channel distribution should be known to the reference cell 20 Mobile Communication and Mobile Computing Kinds of antennas: directional & sectored • Energy is radiated in definite directions, for instance xDirection • So called main propagation directions, for instance Satellite Antennas • Often also used in Mobile Radio Systems, such as GSM, for creation of sectored cells • Seamless radio supply via partial/overlay of sectors z y x Directional Antenna x Sectored Antenna 21 Mobile Communication and Mobile Computing Media Access Methods 22 Mobile Communication and Mobile Computing Principles • Multiplex – Multiple-shift usage of the medium without interference – 4 multiplex methods: • Space • Time • Frequency • Code • Media Access Methods – controls user access to medium 23 Mobile Communication and Mobile Computing SDMA (Space Division Multiple Access) • based on SDM (Space Division Multiplexing, Space Multiplex) • communication channel obtains definite Space for definite Time on the definite Frequency with definite Code • Space Multiplex for instance in the Analog Phone Systems (for each participant one line) and for Broadcasting Stations • Problem: secure distance (interferences) between transmitting stations is required (using one frequency) and by pure Space Multiplex each communication channel would require an own transmitting station • Space Multiplex is only reasonable in combination with other multiplex methods • SDMA for instance by base station dedication to an end-device via Media Access Methods or respectively by segmentation of a Mobile Radio Network to several areas 24 Mobile Communication and Mobile Computing SDMA: Example k1 k2 k3 k4 k5 f1 s SDMA finds selection s – secure distance k6 25 Mobile Communication and Mobile Computing 26 FDMA (Frequency Division Multiple Access) • Based on FDM (Frequency Division Multiplexing, Frequency Multiplex) • i.e. to transmission channels several frequencies are permanently assigned, for instance radio transmitting stations k1 k2 k3 k4 k5 k6 f k6 k5 f1 f2 f3 s FDMA finds selection f4 k4 f5 k3 f6 k2 k1 s – secure distance t Mobile Communication and Mobile Computing 27 TDMA (Time Division Multiple Access) • Based on TDM (Time Division Multiplexing, Time Multiplex) • i.e. to transmission channels is the transmission medium is slot assigned for certain time, is often used in LANs • Synchronization (timing, static or dynamic) between transmitting and receiving stations is required k1 k2 TDMA finds selection k3 k4 k5 f1 k6 f k1 k2 k3 k4 k5 k6 k1 t Mobile Communication and Mobile Computing 28 Combination: FDMA and TDMA, for instance GSM • • GSM uses combination of FDMA and TDMA for better use of narrow resources the used band width for each carrier is 200 kHz f in MHz TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 960 TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 downlink 25 MHz 935,2 TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 915 TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 200 kHz TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 890,2 45 MHz uplink 25 MHz TS0 TS1 TS2 TS3 TS4 TS5 TS6 TS7 TS0 t Mobile Communication and Mobile Computing CDMA (Code Division Multiple Access) • based on CDM (Code Division Multiplexing, Code multiplex) • i.e. to transmission channels the definite Code is assigned, this can be on the same Frequency for the same Time transmitted • derivates from military area • via development of cost-efficient VLSI components • via spread spectrum techniques a good communication security and tiny fault sensitivity • but: exact synchronization is required, code of transmitting station must be known to receiving station, complex receivers for signal separation are required • Noise should not be very high 29 Mobile Communication and Mobile Computing CDMA k1 k2 k3 f1 CDMA decoded k4 k5 k6 30 Mobile Communication and Mobile Computing CDMA illustrated by example The Principle of CDMA can be good illustrated by the example of some party: • communication partners stand closely to each other, each transmission station (Sender) is only so loud, that it does not interfere to neighbored groups • transmission stations (Senders) use certain Codes (for instance, just other languages), they can be just separately received by other transmission stations • receiving station (Listener) attunes to this language (Code), all other Senders are realizing this only as background noise • if receiving station (Listener) cannot understand this language (Code), then it can just receive the data, but it cannot do anything with them • if two communication partners would like to have some secure communication line, then they should simply use a secret language (Code) • Potential Problems: – security distance is too tiny: interferences (i.e. Polish und Czech) 31 Mobile Communication and Mobile Computing CDMA-Example in the theory Sender A • Sends Ad =1, Key Ak = 010011 (set: „0“= -1, „1“= +1) • Transmit signal As =Ad *Ak = (-1, +1, -1, -1, +1, +1) Sender B • sends Bd =0, Key Bk = 110101 (set: „0“= -1, „1“= +1) • Transmit signal Bs =Bd *Bk = (-1, -1, +1, -1, +1, -1) Both signals superpose additively in air • Faults are ignored here (noises etc.) • C = As+ Bs =(-2,0,0,-2,+2,0) Receiver will listen to Sender A • uses Key Ak bitwise (internal product) – Ae = C * Ak =2 +0+0 +2 +2+0 = 6 – Result is greater than 0, so sent bit was „1“ • analog B – Be = C * Bk =-2 +0 +0 -2 -2 +0 = -6, also „0“ 32 Mobile Communication and Mobile Computing Spread Spectrum Techniques dP df dP df f f • Signal is spread by the Sender before the transmission (overblown) • dP/df value corresponds with so called Power Density, Energy is constant (in the Figure: the filled areas) Objective: • Increase of robustness against small band-width faults • listening security: power density of spread-spectrum signals can be lower than that of background noise 33 Mobile Communication and Mobile Computing Spread Spectrum Techniques dP df dP df f dP df f f t • small band-width faults are spread by de-spreading in receiving station • band-pass deletes redundant frequency parts 34 Mobile Communication and Mobile Computing Mobile Radio Networks: Overview 35 Mobile Communication and Mobile Computing Development of Mobile Radio General technological development in mobile telephony Satellite Systems (LEO) UMTS GSM Phase II+ Digital cellular Networks...1800 Mhz Digital cellular Networks...900 Mhz Prognoses Anal. cellular Networks...900 Mhz Anal. cellular Networks...450 Mhz Analog Networks...150Mhz before 1970 1970 1980 1990 2000 2005 36 Mobile Communication and Mobile Computing Correspondent data rates 10Mbit/s UMTS (pico cell) DAB 1Mbit/s DECT EDGE HSCSD/ GPRS 100kbit/s 10kbit/s GSM 1995 UMTS (macro cell) Satellites Satelliten (GEO) 2000 2005 2010 37 Mobile Communication and Mobile Computing 38 Participant quantities in Mobile Radio – world-wide November 2002: 1148 Mio. participants world-wide (1119 Mio. digital & 29 Mio analog) 53069620; 5% 37534680; 3% 165417440; 14% 365190830; 32% 137691590; 12% 369094290; 32% 20059880; 2% (Source: http://www.emc-database.com) 1... Europe: Western 4... Americas (thereof 15.4 Mio. analog) 2... Asia Pacific 5... USA/Canada (thereof 5.4 Mio. analog) 3... Middle East 6... Africa 7… Europe: Eastern 1 2 3 4 5 6 7 Mobile Communication and Mobile Computing 39 Frequency Assignment Circuit Switched Radio Mobile Phones Cordless Phones Wireless LANs TETRA NMT TETRA 380-400 453-457 450-470 CT2 500Mhz CT1+ GSM900 CT1+ 864-868 885-887 890-915 930-932 GSM900 935-960 1GHz 410-430 463-467 (nationally different) TFTS (Pager, aircraft phones) GSM1800 1670-1675 TFTS GSM1800 1710-1785 1800-1805 1805-1880 DECT UMTS 1880-1900 (1885-2025 2110-2200) WLAN IEEE 802.11b Bluetooth IEEE 802.11a: 5,15-5,25; 5,25-5,35; 5,725-5,825 HIPERLAN1 HIPERLAN2 HIPER-Link MHz 2400-2483 2402-2480 2412-2472 HomeRF...(approx.2400) TFTS - Terrestrial Flight Telephone System 5176-5270 Notes: (ca.5200,5600) (ca.17000) - 2,4 GHz license free, nationally different - () written : Prognoses! - today speech over license free frequencies up to 61Ghz -> interesting for high data rates Mobile Communication and Mobile Computing Broadcast/multicast networks • several carrier frequencies but participant obtains carrier for short time only • often in use by taxi- und logistics enterprises etc., each own separated frequency reaches • can use the same frequency packs with FDM- and TDMtechniques, i.e. more efficient handling with narrow resource frequency spectrum • improves transition to fixed network, speech- and data services • not for public access • very reliable, cost-efficient 40 Mobile Communication and Mobile Computing TETRA (Terrestrial Trunked Radio) • former name: Trans-European Trunked Radio • frequencies: 380-390, 410-420 MHz Uplink; 390-400, 420-430 MHz Downlink • bandwidth of each channel: 25 kHz • 1991 started by ETSI • replace of national networks like MODACOM, MOBITEX or COGNITO • Services: – Voice + Data (V+D)- Service: Speech and Data, channel-oriented, uni-, multi- and broadcast possible – Packet Data Optimized (PDO)- Service: packet-oriented, improves connection-oriented or connectionless service, as well as point-to-point and point-to-multipoint communication • carrier services with data rate up to 28,8 kbit/s unprotected; 9,6 kbit/s - protected 41 Mobile Communication and Mobile Computing 42 TETRA, advantages compared with GSM, UMTS • confirmed and/or non-confirmed Group Call (however it’s already possible with GSM today: up to 16 participants) • Group call • listening is possible (so called “open-channel mode”) • very reliable • fast dialing: approx. 300 ms (so called “push to talk”), GSM: several seconds • certain independence of infrastructure (so called “direct mode” between end-devices) • cost-efficient, especially for limited user quantity, because of the „large“ cells x • 10 km • also especially suitable for emergency teams (fire department, ambulance etc.) Mobile Communication and Mobile Computing Cordless Telephony - DECT (Digital Enhanced Cordless Telecommunications) • • • • • • • frequency reach: 1880 - 1990 MHz other than GSM limited to short reaches (1km) in buildings particularly under 50m is not designed for use at high rates mobile phones with GSM and DECT are available in the market 120 full duplex channels TDD (Time Division Duplex) for directional separation with 10ms frame length • frequency reach is divided into 10 carrier frequencies using FDMA • each station 10mW averaged, max. 250mW of transmitting power, GSM – radio phones transmit at 1 to 2W, fixed car phones up to 8W 43 Mobile Communication and Mobile Computing DECT – system architecture D4 D3 D2 HDB PA PT FT Local Networks PA PT VDB D1 FT Local Networks FT.. PT.. PA... HDB.. VDB.. Fixed Radio Termination Portable Radio Termination Portable Terminations Home Data Base Visitor Data Base Global Networks 44 Mobile Communication and Mobile Computing DECT - Multiplex Synchronization 32 bit Used Data (Speech) Signalization 48 bit Used Data (Speech) CRC 160 bit 8 bit 160 bit CRC Secure marker 8 bit 64 bit 0,417 ms DECT-timeslot structure Transmission reach of fixed part (downlink) carrier frequency 1: 1 2 3 4 5 6 carrier frequency 2: 1 2 3 4 5 6 carrier frequency 10: 1 2 3 4 5 6 Transmission reach of mobile part (uplink) .... 11 12 1' 2' 3' 4' 5' 6' .... 11' 12' .... . . . 11 12 . . . 1' 2' 3' 4' 5' . . . 6' .... 11' 12' .... 11 12 1' 2' 3' 4' 5' 6' .... 11' 12' 1728 kHz Transmission principle of DECT-system Channel 1 Channel 2 ... Channel 12 Channel 1’ Channel 2' ... Channel 12' fixed part to mobile part mobile part to fixed part Time duplex with 10 ms frame length Structure of DECT-time multiplex frame 45 Mobile Communication and Mobile Computing 46 Pager systems: overview Eurosignal – to each participant 4 different audio signals using 4 diverse call numbers are assigned. Meaning must be agreed. Receiving stations are at a size of a cigarette packet – 85 senders in the 87 MHz-reach (ultra short waves) – called person location must be approximately known: 3 area codes: North 0509, Middle 0279, South 0709 Cityruf (city call) – additionally to 4 audio- or respectively optical signals transmission of short numerical (15 digitals) or alpha-numerical messages (80 characters) exists optionally, receiving station is smaller than with Eurosignal PEP (Pan European Paging) – preparation for coupling of national services for ERMES – D: Cityruf, F: Alphapage, GB: Europage, I: SIP ERMES (European Radio Message System) – ETSI-Standard for pan-European radio service, similar to PEP but in 169 MHzreach with 60 Mio. addresses Mobile Communication and Mobile Computing GSM: Global System for Mobile Communications 47 Mobile Communication and Mobile Computing GSM: Properties • • • • • • • • • cellular radio network (2nd Generation) digital transmission, data communication up to 9600 Bit/s Roaming (mobility between different net operators, international) good transmission quality (error detection and -correction) scalable (large number of participants possible) Security mechanisms (authentication, authorization, encryption) good resource use (frequency and time division multiplexing) integration within ISDN and fixed network standard (ETSI, European Telecommunications Standards Institute) 48 Mobile Communication and Mobile Computing Providers in Germany (1) • D1 T-Mobile – subscribers: 24,6 Mio (Stand 2003) • Vodafone D2 – old name: Mannesmann Mobilfunk D2 – subscribers: 22,7 Mio (Stand 2003) • E-plus • O2 – old name: VIAG Interkom 49 Mobile Communication and Mobile Computing Providers in Germany (2) Providers Subscribers, millions 2001 2002 2003 World-wide by 2003 D1 T-Mobile 22,6 23,1 24,6 82 Vodafone D2 21,9 - 22,7 112,5 E-Plus - 7,5 - - O2 VIAG Interkom - 3,66 - - 50 Mobile Communication and Mobile Computing 51 GSM: structure Fixed network Switching Subsystems Radio Subsystems OMC Data networks VLR HLR AuC EIR (G)MSC PSTN/ ISDN AuC BSS BSC BTS EIR HLR BSC BTS BTS Call Management Network Management Authentication Centre Base Station Subsystem Base Station Controller Base Transceiver Station Equipment Identity Register Home Location Register MS (G)MSC OMC PSTN VLR ISDN BSS Mobile Station (Gateway) Mobile Switching Centre Operation and Maintenance Centre Public Switched Telephone Network Visitor Location Register Integrated Services Digital Network MS MS MS Mobile Communication and Mobile Computing GSM: Structure Operation and Maintenance Centre (OMC) • logical, central structure with HLR, AuC und EIR Authentication Centre (AuC) • authentication, storage of symmetrical keys, generation of encryption keys Equipment Identity Register (EIR) • storage of device attributes of allowed, faulty and jammed devices (white, grey, black list) Mobile Switching Centre (MSC) • arrangement centre, partial as gateways to other nets, assigned to one VLR each Base Station Subsystem (BSS): technical radio centre • Base Station Controller (BSC): control centre • Base Transceiver Station (BTS): radio tower / antenna 52 Mobile Communication and Mobile Computing 53 Radio technical structure 1 TDMA-Frame, 144 Bit in 4,615 ms 8 TDMA-channels, together 271 kBit/s inclusive error protection information 124 radio frequency channels (carrier), each 200 kHz 890 935 downlink uplink 915 MHz 960 MHz 2 frequency wavebands, for each 25 MHz, divided into radio cells • One or several carrier frequencies per BSC • Physical channels defined by number and position of time slots Mobile Communication and Mobile Computing GSM: protocols, incoming call BSS VLR BSS (8) (8) (9) BSS (12) (4) (3) (8) (9) (12) (7) (11) (6) (10) MSC HLR (4) (5) (2) GMSC (1) PSTN/ ISDN (8) BSS (1) Call from fixed network was switched via GMSC (2) GMSC finds out HLR from phone number and transmits need of conversation (3) HLR checks whether participant for a corresponding service is authorized and asks for MSRN at the responsible VLR (4) MSRN will be returned to GMSC, can now contact responsible MSC 54 Mobile Communication and Mobile Computing GSM: protocols, incoming call BSS VLR BSS (8) (8) (9) BSS (12) (4) (3) (8) (9) (7) (11) (6) (10) MSC HLR (4) (5) (2) GMSC (12) (8) BSS (5) GMSC transmits call to current MSC (6) ask for the state of the mobile station (7) Information whether end terminal is active (8) Call to all cells of the Location Area (LA) (9) Answer from end terminal (10 - 12) security check and connection construction (1) PSTN/ ISDN 55 Mobile Communication and Mobile Computing GSM: protocols, outgoing call BSS BSS (4) (1) BSS HLR VLR (2) (3) MSC (1) Demand on connection (2) Transfer by BSS (3-4) Control for authorization (5) Switching of the call demand to fixed net (5) GMSC 56 Mobile Communication and Mobile Computing GSM: channel strucure Traffic Channel • speech- / data channel (13 kbit/s brutto; differential encoding) • units of 26 TDMA - Frames • Half-rate traffic channel: for more efficient speech encoding with 7 kbit/s Control Channel • Signal information • Monitoring of the BSCs for reconnaissance of Handover Broadcast Control Channel • BSC to MS (identity, frequency order etc.) Random Access Channel • Steering of channel entry with Aloha-procedure Paging Channel • signalize incoming calls 57 Mobile Communication and Mobile Computing Databases Home Location Register (HLR), stores data of participants, which are reported in an HLR-area – Semi-permanent data: • Call number (Mobile Subscriber International ISDN Number) - MSISDN, e.g. +49/171/333 4444 (country, net, call number) • identity (International Mobile Subscriber Identity) - IMSI: MCC = Mobile Country Code (262 for .de) + MNC = Mobile Network Code (01-D1, 02Vodafone-D2, 03-eplus, 07-O2) + MSIN = Mobile Subscriber Identification Number • Personal data (name, address, mode of payment) • Service profile ( call transfer, Roaming-limits etc.) – Temporary data: • MSRN (Mobile Subscriber Roaming Number) (country, net, MSC) • VLR-address, MSC-address • Authentication Sets of AuC (RAND (128 Bit), SRES (128 Bit), KC (64Bit)) • charge data 58 Mobile Communication and Mobile Computing Databases Visitor Location Register (VLR) • local database of each MSC with following data: – – – – IMSI, MSISDN service profile accounting information TMSI (Temporary Mobile Subscriber Identity) - pseudonym for data security – MSRN – LAI (Location Area Identity) – MSC-address, HLR-address 59 Mobile Communication and Mobile Computing GSM: mobile telephone areas MSC-area = VLR-area Handover Location Area (LA) radio- with cell BTS LA = smallest addressable unit 60 Mobile Communication and Mobile Computing Connection HLR, VLR HLR MSC-area VLR advantage of the architecture: Location Update at limited mobility, as a rule only at VLR, rarely at (perhaps far remote) HLR Location area 61 Mobile Communication and Mobile Computing 62 Localization at GSM VLR 10 VLR 9 IMSI LA 2 HLR 26 32311 VLR 9 IMSI z.B. 0x62F220 01E5 LA 3 +49 0177-26 32311 LA 2 participant call number in HLR LA 5 LA 3 Provider net-entry code country code number Mobile Communication and Mobile Computing 63 Data transmission • • • • • each GSM-channel configurable as a data channel; similar structure like ISDN-B and -D-channels data rates up to 9600 bit/s now delay approximately 200 ms speech channels have as a rule higher priority as data channels kinds of channels: – transparent (without error correction; however FEC; fixed data rate; error rate 10-3 up to 10-4) – non-transparent (repeat of faulty data frames; very low error rate, but also less throughput) • Short-Message-Service (SMS) – connectionless transmission (up to 160 Byte) on signal channel • Cell Broadcast (CB) – connectionless transmission (up to 80 Byte) on signal channel to all participants, e.g. one cell Mobile Communication and Mobile Computing Data transmission - structure BSC MSC IWF ISDN UDI BTS Modem TA PSTN Internet IWF - Inter Working Function UDI - Unspecified Digital TA - Terminal Adapter Modem 64 Mobile Communication and Mobile Computing Security aspects: Subscriber Identity Module (SIM) Chip-card (Smart Cart) to personalize a mobile subscriber (MS): • • • • • IMSI (International Mobile Subscriber Identity) participant special symmetric key Ki, stored also at AuC algorithm “A3” for Challenge-Response-Authentication algorithm “A8” for key generation of Kc for content data PIN (Personal Identification Number) for entry control Temporary data: • TMSI (Temporary Mobile Subscriber Identity) • LAI (Location Area Identification) • Encryption key Kc 65 Mobile Communication and Mobile Computing Security in GSM-networks SIM • Entry control and cryptographic algorithms Single-sided authentication (participant against network) • Challenge-Response-method (cryptographic algorithm: A3) Pseudonyms of participants at the Radio interface • Temporary Mobile Subscriber Identity (TMSI) Connection encoding on the Radio interface • Key generation: A8 • Encryption: A5 66 Mobile Communication and Mobile Computing MS Ki A3 Security aspects: Authentication max. 128 Bit Authentication Request RAND (128 Bit) MSC, VLR, AuC Random number generator Ki A3 SRES Authentication Response SRES (32 Bit) • • • • Location Registration Location Update with VLR-change Call setup (in both directions) SMS (Short Message Service) = 67 Mobile Communication and Mobile Computing Security aspects: Session Key MS Netz Ki A8 Kc • Authentication Request RAND (128 Bit) 64 Bit Key generation: Algorithm A8 – – – – – – Stored on SIM and in AuC with Ki parametric one way function no (Europe, world wide) standard can be determined by net operator Interfaces are standardized combination A3/A8 known as COMP128 Random number generator Ki A8 Kc 68 Mobile Communication and Mobile Computing Security aspects: encryption at the Radio interface MS Net TDMA-framenumber K Ciphering Mode Command c TDMA-framenumber Kc A5 A5 Key block + Plain text block Ciphering Mode Complete Encrypted Text 114 Bit • Data encryption through algorithm A5: – stored in the Mobile Station – standardized in Europe and world wide – weaker algorithm A5* or A5/2 for specific countries + Plain text block 69 Mobile Communication and Mobile Computing GSM-Security: assessment • cryptographic methods secret, so they are not „well examined“ • symmetric procedure – consequence: storage of user special secret keys with net operators required • low key length Ki with max. 128 Bit (could be hacked by using Brute Force Attack in 8-12 hours) • no mutual authentication intended – consequence: Attacker can pretend a GSM-Net • no end-to-end encryption • no end-to-end authentication • Key generation and -administration not controlled by the participants 70 Mobile Communication and Mobile Computing GSM Phase II+ HSCSD, GPRS 71 Mobile Communication and Mobile Computing HSCSD: High Speed Circuit Switched Data 72 Mobile Communication and Mobile Computing Properties • higher data rate because of channel bundling • parallel usage of several time slots (TCH) of one frequency on Um • more efficient channel encoding (14,4 kbit/s per TCH) • Data rates from 9,6 up to 53,8 kbit/s • asymmetric transmission (1TCH Uplink / 3TCH Downlink) 73 Mobile Communication and Mobile Computing HSCSD data rates non transparent transparent up- / downlink 100% coverage 1+1 2+2 1+3 1+4 9,6 19,2 ----- 95% coverage 100% coverage 14,4 28,8 ------- 9,6 19,2 28,8 38,4 95% coverage 13,2 26,4 39,6 53,8 74 Mobile Communication and Mobile Computing HSCSD: structure BSC MSC IWF ISDN UDI BTS Modem TA n time slots (TCH) of each TDMA frame (theoretically max. 8) IWF - Inter Working Function UDI - Unspecified Digital TA - Terminal Adapter PSTN Internet Modem 75 Mobile Communication and Mobile Computing HSCSD: changes n time slots (TCH) of each TDMA frame (theoretically max. 8) BTS Um BSC Abis MSC A multiplex of the time slots on each 64 kBit/s channel certain changes are necessary at the component several changes at the software/firmware minimal changes at the software/firmware 76 Mobile Communication and Mobile Computing HSCSD radio interface Required time for setting to transmission standby Required time for setting to receiving standby MS RECEIVE 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 MS TRANSMIT 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 MS MONITOR Required time for signal strength measure and setting to receiving standby • parallel usage of several time slots limited to one frequency • Cost factor limits number of used TCH‘s to (2+2) or (1+3, uplink, downlink) 77 Mobile Communication and Mobile Computing Assessment of HSCSD + existing net structure and accounting model maintained + in comparison to GPRS only around1/5 of investment necessary + HSCSD is still circuit switched + has defined QoS- settings (data rate, delay) – one logical channel will be switched on all interfaces for the time of the connection – Non-efficient for burst-like traffic (Internet) or Flat Rate billing (Logistics) – no international acceptance (Roaming!) • uses also more resources on the radio interface – problems with handover into a new cell 78 Mobile Communication and Mobile Computing GPRS: General Packet Radio Service 79 Mobile Communication and Mobile Computing Properties • • • • • • Packet switching service (end- to- end) Data rates up to 171,2 kbit/s (theoretical) Effective and flexible administration of the radio interface adaptive channel encoding Internetworking with IP- and X.25 nets standardized dynamic sharing of resources with „classical“ GSM speech services • Advantage: Billing and Accounting according to data volume • Disadvantage: cost intensive additional net hardware necessary 80 Mobile Communication and Mobile Computing Properties – point-to-point-Packet transfer service • PTP-CONS (PTP Connection oriented Network Service) – connection oriented, similar to X.25 • PTP- CLNS (PTP Connectionless Network Service) – connectionless, similar to IP – point- to- multipoint - group communication 81 Mobile Communication and Mobile Computing 82 GPRS: Structure GSM BSC GPRS Nets other operators MSC HLR BTS Internet SGSN other packet switching networks GGSN GPRS Backbone Frame Relay / ATM Border Gateway GGSN SGSN - Serving GPRS Support Node GGSN - Gateway GPRS Support Node signalization data user data Mobile Communication and Mobile Computing 83 GPRS: Changes GMSC n time slots (TCH) per TDMA frame (theoretically max. 8) per packet! public remote fixed nets Circuit switched traffic A BTS Abis Um HLR/AuC GPRS register Gs BSC PCU MSC MAP Gb Packet arranged traffic SGSN Gn MAP Gi GGSN other packet switching networks modified network components new components or extensively modified components Existing components PCU - Packet Control Unit Mobile Communication and Mobile Computing Tasks: SGSN, GGSN SGSN: - mobility management - session management MAP Signalization (GGSN) - QoS - security BSS PCU Client Client MAP Signalization (SGSN) Internet Intranet SGSN BSS PCU BSS PCU External Data Domain HLR GGSN SGSN SGSN, GGSN: - Routing - Signalization - Resource management Server 84 Mobile Communication and Mobile Computing Tasks of the SGSN • Packet delivery • mobility management – apply/ sign off of terminals – localization • LLC (Logical Link Control) management • authentication • billing 85 Mobile Communication and Mobile Computing 86 Tasks of the GGSN • mediator between GPRS backbone and external data networks (Internet, X-25 etc.) • converts GPRS packets, data Protocol (PDP) into the corresponding structure • also converts PDP addresses of incoming packets into GSM address of the receiver • saves current data for the SGSN address of the participant as well as their profile and data for authentication and invoice Mobile Communication and Mobile Computing GPRS: air interface Radio Link Control (RLC) • Segmentation of the LLC-Frames in RLC blocks • Block size dependent on short-term channel conditions • Backward error correction and data flow control by Automatic Repeat Request (ARQ) protocol – repeating not repairable RLC blocks selectively Medium Access Control ( MAC) • Channel reservation contains: - one/several time slots (Packet Data Channels PDCH) of one frequency – one uplink status flag (USF) per Packet Data Channel (PDCH), channel partition of up to 8 ms 87 Mobile Communication and Mobile Computing GPRS: air interface Medium Access Control ( MAC) • Reservation in the uplink (MS to BSS): • MS sends reservation request on a Random Access Channel (Slotted ALOHA) – BTS allocates a (split) channel and sends packet assignment – MS sends data depending on the current priority (USF flag) • Reservation in the Downlink (BSS to MS): – BTS displays transmitting request and informs about the reserved channel – MS supervises the reserved channel and receives 88 Mobile Communication and Mobile Computing GPRS: air interface Physical Link Control • adaptive forward error correction (FEC) dependent on shortterm channel conditions • temporal scrambling (Interleaving) of the bursts and Mapping on reserved PDCH (Packet Data Channel) • procedure to recognize overbooking situations on the physical channel GPRS Channel Encoding Scheme Code Rate Payload BCS Precoded USF Tail bits Coded bits Punctured bits Data rate (kbit/s) CS-1 1/2 181 40 3 4 456 0 9.05 CS-2 ~ 2/3 268 16 6 4 588 132 13.4 CS-3 ~ 3/4 312 16 6 4 676 220 15.6 CS-4 1 428 16 12 0 456 0 21.4 89 Mobile Communication and Mobile Computing Quality of Service • QoS profile agrees service parameters inside the whole network • Agreed for the duration of one PDP (Packet Data Protocol) context (session, end terminal is obtainable for the duration of the context, e.g. obtainable over Internet ) : – temporary address (IP) for mobile station – tunneling information, among others GGSN, which is used for access to corresponding packet arranged network – type of the connection – QoS profile • QoS profile commits: – precedence class, priority against other services (high, normal, low) – packet delay class, times are valid for traffic inside the GPRSnetwork – reliability class – peak throughput class – mean throughput class 90 Mobile Communication and Mobile Computing Quality of Service Packet delay classes Size 128 octets 1024 octets Class Mean Delay 95% Delay Mean Delay 95% Delay 1 (predictive) < 0,5 s < 1,5 s <2s <7s 2 (predictive) <5s < 25 s < 15 s < 75 s 3 (predictive) < 50 s < 250 s < 75 s < 375 s 4 (best effort) Best effort Security classes Class Lost packet -9 1 10 2 10 3 10 -4 -2 Probability for Out of Duplicated Sequence packet packet -9 10 -5 10 -5 10 -9 10 -5 10 -5 10 Corrupted packet -9 10 -6 10 -2 10 91 Mobile Communication and Mobile Computing Quality of Service GPRS- using data rates Coding # of timeslots Scheme 1 CS-1 9,05 CS-2 13,4 CS-3 15,6 CS-4 21,4 2 18,1 26,8 31,2 42,8 3 27,15 40,2 46,8 64,2 4 36,2 53,6 62,4 85,6 5 45,25 67 78 107 6 54,3 80,4 93,6 128,4 7 63,35 93,8 109,2 149,8 8 72,4 107,2 124,8 171,2 • CS 3 and CS 4 are only reasonable in the second phase of GPRS introduction • They will be used adaptively at corresponding good quality of radio connection • CS 4 does not comprise error correction, code rate = 1! 92 Mobile Communication and Mobile Computing Assessment of GPRS + An up to 4 times higher data rate in comparison to ordinary GSMdata services + better resource management through packet arranged service + „always on” data service (email, etc.) + GPRS is a more suitable carrier for services like WAP - IP-derivate, no true guaranties (QoS) - development of the network infrastructure is relatively expensive, particularly regarding introduction to UMTS (return of investment) - GPRS doesn’t give such data rates like advertising has sometimes promised 93 Mobile Communication and Mobile Computing 26.4 kbit/s 13.2 kbit/s 9.6 kbit/s CS 1 CS 2 40.2 kbit/s 27.2 kbit/s 26.8 kbit/s 18.1 kbit/s 13.4 kbit/s 9 kbit/s flow GPRS Packet arranged 39.6 kbit/s HSCSD Channel packing, NT Data rate Development of the GSM-data services 94 Mobile Communication and Mobile Computing Enhanced Services - EMS (enhanced message service) • Uses widespread existing infrastructure (SMS) • new Mobile telephones necessary • allows sending and receiving of messages with formatted texts, melodies, graphics (32 x 32 Pixel) and animations (16 x 16 Pixel) – e.g. NOKIA • new applications like Mobile Ticketing • tickets will be transferred to mobile phone like a bar code and checked at the admission • EMS enables transition to MMS (multimedia messaging service), which allows transmission of multimedia enriched messages over UMTS-Network (photos, parts of videos) • MMS requires new network elements in the Infrastructure of the operators 95 Mobile Communication and Mobile Computing MMS - architecture MMS User Databases HLR LDAP MMS Relay WAP or MExE (e.g. Java and TCP/IP) MMS User Agent alien MMS Relay GSM-MAP or IS-41-MAP or TCP/IP SMTP, HTTP, POP3, IMAPv4 SMTP MMS Server (e.g. E-Mail) Based on materials from 3GPP, http://www.3gpp.org MMS Server (e.g. Fax) ... MMS Server (other service) 96 Mobile Communication and Mobile Computing UMTS: Universal Mobile Telecommunications System, 3G, 3rd generation of mobile radio 97 Mobile Communication and Mobile Computing 98 IMT-2000 - structure individual carrier IMT-SC UWC-136 (EDGE) multiple carrier IMT-FT DECT IMT-DS UTRA-FDD IMT-MC CDMA2000 • 3 systems - UMTS - CDMA2000 - UWC-136 TDMA • 2 core technologies - TDMA - CDMA IMT-2000 FDD CDMA UTRA-TDD TDD IMT-TC TD-SCDMA satellite- supported network expansion: - SW-CDMA: Satellite Wideband CMDA - SW-CDTMA: Satellite Wideband CDMA/TDMA (Hybride procedure) - SAT-CDMA: Satellite CDMA - ICO RTT: ICO Radio Transmission Technology ICO RTT... Standard by ICO Global Communications IMT ... International Mobile Telecommunications UTRA ... Universal Terrestrial Radio Access UWC ... Universal Wireless Communications source: www.UMTS-Report.com IMT-2000 family of radio interfaces : – – – In europe UMTS – – IMT-DS (Direct Spread) • UTRA-FDD (UMTS) IMT-MC (Multi Carrier) • CDMA2000, USA IMT-TC (Time Code) • UTRA-TDD (UMTS), TDSCDMA (Synchronous Code Division Multiple Access, China) IMT-SC (Single Carrier) • UWC-136, USA IMT-FT (Frequency time) • DECT Mobile Communication and Mobile Computing Worldwide frequency assignment for IMT-200 • developed by ITU PCS... Personal Communication System MSS...Mobile Satellite Service PHS... Personal Handy-Phone System 99 Mobile Communication and Mobile Computing UMTS - Facts • • • • consideration: early 90ies Universal Mobile Telecommunications System, developed in the EU (ETSI: European Telecommunication Standards Institute) UMTS is the European implementation of IMT-2000 (International Mobile Telecommunications by the year 2000) Start of network expansion: – in Europe: 2003 (some trials, e.g. British Telecom on Isle of Man, 2002) – in the USA: 2005 – in Japan since 2000 : NTT DOCOMO 100 Mobile Communication and Mobile Computing 101 Frequency award in Europe 1700 • • • 1750 1800 1850 1900 FDD MSS Uplink 1950 TDD GSM1800 Downlink GSM1800 Uplink DECT TDD 230 MHz frequency range for IMT-2000 2000 FDD MSS Downlink 2050 2100 2150 2200 MSS…Satellite- based at FDD symmetrical spectrum is necessary, not at TDD (time slots at same frequency) gradual new assignment of wavebands depending on development of the need up to 300-500 MHz frequency range in 2008 source: www.UMTS-Report.com Mobile Communication and Mobile Computing Characteristics • system general , worldwide roaming • high data rates: 144 kbit/s mobile, up to 2 Mbit/s at local area • fusion of different mobile radio communications-, wireless- and pager-systems into one common system • speech-, data-, and multimedia- information services independent of used network access • support of different carrier services: – real-time capable/not real-time capable – circuit switched/ packet switched • Roaming also between UMTS and GSM and satellite networks • Asymmetrical data rates in up-/downlink 102 Mobile Communication and Mobile Computing 103 UMTS- Disadvantages • • Technology not yet perfect rent ability of pico cells („Hotspots“) not yet analyzed • • • strong contention by WLAN increased radiation exposure high data rate only obtainable sometimes (High-Tech-network expansion, stationary and exclusive usage necessary!) • because of high license costs costs) high charges necessary (around double GSM- Mobile Communication and Mobile Computing UMTS - Performance Transmission Real- time (Video) Not Real-time (SMS etc.) Bit error rate 10-3 … 10-7 10-5 … 10-8 Permitted delay 20ms … 300ms > 150 ms UMTS Photo Report GPRS ISDN Web Mail PSTN GSM ~ 0 sec Video Photo Report Video Photo Web Mail Web Mail 10 sec Report Video Photo Web Photo 1 min Report Video 10 min 1h source: Mobilkom Austria 104 Mobile Communication and Mobile Computing UMTS - Hardware • • • big color displays high resolution True Color 105 Mobile Communication and Mobile Computing 106 UMTS- cell structure UMTS-Core Network circuit switched PSTN/ ISDN Visitor Location Register Base Station Controller BTS Radio access network BTS BTS GSM - BSS Quelle: Mobilkom Austria Gateway Mobile Switching Centre Home Location Register Gateway GPRS Support Node Internet customer 3G- Serving GPRS Intranet Support packetNode 3G Mobile Switching Centre switched Radio Network Controller Radio Network Controller BTS BTS BTS BTS BTS BTS UTRAN- UMTS Terrestrial Radio Access Network Mobile Communication and Mobile Computing UMTS: cell structure Satellite Zone 4: Global “World cell” Zone 3: Suburban “Macro cell” Zone 2: Neighborhood Zone1: In-building “Micro cell” “Pico cell” PDA terminal Basic terminal Audio/visual terminal Integration with the fixed network 107 Mobile Communication and Mobile Computing UMTS: hierarchical cell structure principle: - all neighbor cells use same frequency channel - only one waveband is necessary for cellular construction - further wavebands are necessary for hierarchical structure Global Regional Lokal Home/ Office World Micro Macro Max. velocity (mph) Pico expansion Data rate (kbit/s) Special features World Cell global - Macro Cell Up to 1,24 miles 144 310 complete national UMTS support Micro Cell Up to 0,62 miles 384 74 Greater cities, commonly used Pico Cell > 60miles 2000 6,2! „Hotspots“ – e.g. airport, station no UTRAN, other technology! 108 Mobile Communication and Mobile Computing Classification 109 Mobile Communication and Mobile Computing Service concept • Virtual Home Environment (VHE): offered services are freely configurable, configuration still exists in the whole network • choose of service quality and also arising costs • behave at bottlenecks (data rates, etc.) configurable • dynamic customization to connection 110 Mobile Communication and Mobile Computing UPT: Universal Personal Telecommunication Service • one phone number for several devices (CallManagement) • subscriber localization e.g. with SIM-card • call passing • virtual mobility of fixed networks 111 Mobile Communication and Mobile Computing Intelligent networks • Implementation of basic services like subscriber localization billing etc. • supply of value added service (Voice-Mailbox, etc.) – possibility of easy, fast introduction of new services – flexible service administration – usage of services also from foreign network possible – better control of service parameters through subscriber 112 Mobile Communication and Mobile Computing UMTS: basic network structure • Access Network: base stations, responsible for radio contact to mobile end devices • Core Network (Fixed Network): responsible for structure of connections • Intelligent Network (IN): responsible for billing, subscriber localization, Roaming, Handover Intelligent Network Access Network User Equipment (UE) Core Network 113 Mobile Communication and Mobile Computing General reference architecture UE UTRAN Uu • CN Iu UTRA: UMTS Terrestrial Radio Access – UTRAN (UTRA- Network) contains several radio subsystems, so called Radio Network Subsystems (RNS) and contains functions for mobility management – RNS controls handover at cell change, capacitates functions for the encoding and administrates the resources of the radio interface – Uu connects UTRAN with mobile end devices, so called User Equipment (UE), is comparable with Um in GSM – UTRAN is connected over Iu with the Core Network, comparable with the A interface in GSM between BSC and MSC – CN contains the interfaces to other networks and mechanisms for connection handover to other systems 114 Mobile Communication and Mobile Computing The UMTS-radio interface UTRA (UMTS Terrestrial Radio Access) • Two modes defined: – UTRA/FDD (Frequency Division Duplex) • mainly in suburban areas for symmetrical transmission of speech and video • data rates up to 384 kbit/s, supra-regional roaming • for circuit- and packet switched services in urban areas – UTRA/TDD (Time Division Duplex) • mainly in households and other restricted areas (company's premises, similar to DECT) • for broadcast of speech and video, both symmetrical: up to 384 kbit/s • also asymmetrical: up to 2 Mbit/s 115 Mobile Communication and Mobile Computing UTRA/FDD • • • • puts wide- band- CDMA (W-CDMA) together with DSSS (Direct Sequence Spread Spectrum) as spread spectrum technique channel separation by carrier frequencies, spreading code and phase position (only uplink) ca. 250 channels for used data, data rates up to 2 Mbit/s complex performance control necessary f in MHz 2169,7 2110,9 carrier 12 . . . carrier 1 downlink 5 MHz 1979,7 1920,9 carrier 12 . . . carrier 1 190 MHz uplink t 116 Mobile Communication and Mobile Computing UTRA/TDD • • • • • • • puts wideband- TDMA/CDMA together with DSSS sends and receives on same carrier (TDD) ca. 120 channels for used data, data rates up to 2 Mbit/s channel separation by spread code and time slots less spreading than at FDD precise synchronization necessary lower demand for performance control f in MHz uplink downlink 2020,1 2010,1 carrier 6 1920,1 carrier 4 . . . carrier 1 1900,1 carrier 5 5 MHz t 117 Mobile Communication and Mobile Computing 118 Frequency award for UMTS satellite- based 1885 1920 1980 2010 2025 2110 2170 MHz terrestrial 60 GHz MBS Extension Bands (for a future market potential ..from 2005) Extension Band 1 (worldwide similar) – partly terrestrial, partly satellite- based Existing Nets 470 862 satellite-based GSM, DECT 2290 2300 2520 2670 2700 2900 MHz 880 1885 MHz 1675 1710 MHz Mobile Communication and Mobile Computing UMTS-licenses in Germany • • • • • • E-Plus Hutchison 8.394.492.363 € RegTP determined: Group 3G - till end of 2003 25 % network coverage 8.408.706.278 € - till end of 2005 50 % network coverage Vodafone (Mannesmann Mobilfunk) 8.422.920.192 € MobilCom Multimedia 8.369.848.095 € T-Mobil 8.478.344.232 € O2 (VIAG Interkom) 8.445.008.001 € 17.08.2000: each license got 2 x 5 MHz packets, 60 MHz have been given away altogether, 150 MHz are available altogether 119 Mobile Communication and Mobile Computing Summary • introduced variants are the proposals, which will be supported by Europe, Japan and partly by the USA • worldwide accessibility can be realized only with multimode end devices • even in Europe combined UTRA-FDD/UTRATDD/GSM- devices are necessary (those are realized by the identical frame time of 10ms at relatively low costs) 120 Mobile Communication and Mobile Computing Wireless Local Networks, WLAN 121 Mobile Communication and Mobile Computing Why do we need wireless LANs? Advantages • flexibility • Ad-hoc-network realizable with less expenditure • No problems with cables Disadvantages • high error vulnerability on the transmission link in comparison to Standard-LANs • National restrictions, no international standards at used frequency bands (Industrial Scientific Medical (ISM)- Band) • security, costs 122 Mobile Communication and Mobile Computing Application areas • • • • • • networks in exhibition halls hospitals warehouses airports structure of networks in historic buildings extension of existing wired local area networks in offices, universities etc. 123 Mobile Communication and Mobile Computing Problems with the use of WLAN‘s – physical problems • interference: band spreading • echo: use of special antennas • Hidden Terminal problem: use CSMA/CA – data security • Wired Equivalent Privacy (WEP) service further development WiFi (Wireless Fidelity), WPA (WiFi Protected Access) 124 Mobile Communication and Mobile Computing Standards • IEEE 802.11 (a,b,g ; optional e,h,i) – frequency band 2,4 GHz, also in the 5GHz - band – data rates: 1 bis 11 Mbit/s (at present, later up to 20 (2,4 GHz) or 54 Mbit/s (5,4 GHz)) – WiFi: Wireless Fidelity, certificate from the WECA (Wireless Compatibility Allicance), secures the interoperability between the Radio- LANs and contains improved security mechanisms • HomeRF • Bluetooth (IEEE 802.15) – Frequency band: 2,4 GHz – Data rate: 1 Mbit/s; in the future also 20 Mbit/s – connection of peripherals • HIPERLAN (ETSI) / Wireless ATM – frequency bands 5,15 / 5,30 GHz and 17,1 / 17,3 GHz – data rates: 24 Mbit/s or 155 Mbit/s – however no practical relevance 125 Mobile Communication and Mobile Computing IEEE 802.11b • frequency: – 2,4 GHz frequency band, also called ISM (= Industrial Scientific Medical Band), not regulated – 850 - 950 nm at infrared • transmission power: – min. 1mW – max. 100mW in Europe (1W in the USA) • reach: – of 10m (IR) to 30km or more with the help of special antennas (directional antennas) 126 Mobile Communication and Mobile Computing Basic WLAN- structure Ad-hoc-network: 3 connected infrastructure networks: STA4 STA5 AP AP AP - Access Point AP 127 Mobile Communication and Mobile Computing System architecture IEEE 802.11 802.x LAN ESS STA1 802.11 LAN BSS1 Access Point Portal Distribution System Access Point BSS2 STA2 802.11 LAN STA3 128 Mobile Communication and Mobile Computing System architecture IEEE 802.11, concepts • Station (STA) – device with 802.11- concurring interface • Access Point – allows the access to the distribution system for registered stations and secures accessibility of the stations also beyond the BSS • Coordination Function (CF) – logical functional unit, which decides when a station can send • Basic Service Set (BSS) – consists of several stations, that were controlled by an CF, e.g. BSS2 and STA2, STA3 129 Mobile Communication and Mobile Computing System architecture IEEE 802.11, concepts • Distribution System – connects several BSS over access points and forms a logically larger net • Extended Service Set (ESS) – Radio networks, which are connected over Distribution System • Portal – allows transition into other networks 130 Mobile Communication and Mobile Computing 131 Overview • 802.11 is the most frequently used solution for wireless connection; very strong distribution on the market • interesting future option: „Seamless Handover“ between GSM and IEEE 802.11; supported by Cisco, Intel etc. (alternative to UMTS?) • higher data rates already standardized or in use – 802.11a: physical layer at 5 GHz – Band, data rates up to 54 MBit/s – 802.11b: extension to physical layer for the 2,4 GHz – band, data rates up to 11 MBit/s, products available – 802.11g: at present the industry works on an extension, shall allow the up to 54Mbit/s in the frequency band around 2.4 GHz – Study Group 5GSG: examines the harmonization between IEEE 802.11 and ETSI HiperLAN – Task Group e: MAC functions for QoS-Management and to refine improved safety functions, introduction of service classes etc. Mobile Communication and Mobile Computing 132 802.11 – Norms for WLAN 802.11 Since end of 1990; RadioLAN; B=1-2 MBit/s; ISM-Band F=2,4GHz; low Interoperability and bit rate! 802.11b 11MBit/s, actual Standard, existed NICs and APs; ISM-Band F=2,4GHz; possesses further sub-standards 802.11a Since 2000; competition with 802.11b; up to 54 MBit/s; F=5,1 GHz, correspond. national restrictions: in the buildings 802.11g Ratification March, 2003; first pre-standard products; ISM-Band 2,4GHz; up to 54 MBit/s; 802.11e Sub-standard; planed for end 2003; use of QoS-approaches; realization of multimedia applications/ Voice over IP over WLAN 802.11h Sub-standard / method for 802.11a; optional functionality – transmission power control of radio interface by national via RegTP prescribed norms; correspond. especially for Germany 802.11a or h 802.11i Sub-standard; security approaches for WLAN (encryption, authentication) WPA WiFi Protected Access; Substandard; competition with 802.11i 802.11c Sub-standard; Method of Wireless-Bridging 802.11d Sub-standard; country specifics for 802.11b 802.11f Sub-standard; Routing between radio cells of different vendors by IAPP (Inter-AccessPoint Protocol) Mobile Communication and Mobile Computing Parameters 133 Standards 802.11 802.11 802.11b 802.11a / h 802.11g Frequency band, GHz 2,4 (ISM-Band) 2,4 (ISM-Band) 5,1 2,4 (ISM-Band) Bit rate, MBit/s 1-11 11 54 54 Use field building, territory building, territory in the buildings building, territory Deployment End 1990 actually Since 2000 Since March 2003 Available Hardware Marketable NICs and APs Marketable NICs and APs Experimental operation Pre-standard Products Data security WEP 64/128/256 bit WEP 802.11i - security approaches for WLAN (encryption, authentication); WPA - WiFi Protected Access (competition with 802.11i) QoS for multimediatransmission none none 802.11e (Ende 2003): use of QoSapproaches; realization of multimedia applications/ Voice over IP Problematic • • low bit rate low bit rate low interoperability National restrictions Pre-standard Mobile Communication and Mobile Computing Example: Lucent Wavelan 802.11b WLAN Card • Wireless connection that acts just like a conventional Ethernet link • Technical specifications: – 11 Mbps wireless connection – 40-bit WEP or 104-bit RC4 link layer encryption – Interoperability with other cards of IEEE 802.11b (i.e. Cisco Aironet or the Apple Airport Card) – Tiny size - a PCMCIA card less than 1 inch – Cross-platform support (Linux, Mac, and Win*) – Very low cost (comparable to a PCMCIA 10/100 Ethernet card) http://www.lucent.com/ 134 Mobile Communication and Mobile Computing Example: Globalsuntech 802.11b products • Bit rates: 22/11/5.5/2/1 MBit/s per channel • WEP 64/128/256 Bit • Available devices: – – – – Card Bus PCMCIA Card PCI Card Mini USB • DSSS; selectable channels: – USA, Canada - 11 channels – Europe - 13 channels – Japan - 14 channels • Sensitivity, range: – 80dBm for 22MBit/s – 92dBm for 1MBit/s http://www.globalsuntech.com/ • Cross-platform support (Linux, Win*) 135 Mobile Communication and Mobile Computing Further Scenarios (1) Scenario 1: Wireless Access Wireless Access Point (Hub Type) LAN WLAN PCs Wireless PC 136 Mobile Communication and Mobile Computing Further Scenarios (2) Scenario 2: Wireless Bridging Ethernet Hub Wireless Access Point (Bridge Type) Wireless PCs WLAN LAN 137 Mobile Communication and Mobile Computing Further Scenarios (3) Scenario 3: Share Wireless AP Internet Cable/DSL-Modem Wireless Access Point (Router Type) WAN WLAN Wireless PCs 138 Mobile Communication and Mobile Computing Further Scenarios (4) Scenario 4: Wireless/Wired Routing Internet Cable/DSL-Modem Cable/DSL- Wireless/ Wired Router WAN LAN LAN WLAN Wireless PCs 139 Mobile Communication and Mobile Computing UMTS vs WLAN 140 Mobile Communication and Mobile Computing 141 Mobility and data rates mobility UMTS: better mobility, connectivity WLAN: higher data rates, more cheap, but no telephone Vehicle 0,4 WLAN 2,0 Walk 3G – UMTS UMTS (best support) 5,5 2G TDSL 65,5 ISDN in minutes, trailer , 30 MB Source: Focus, 34/2002 Fixed WLAN Bluetooth 0,1 Source: http://www.netant.no LAN 1 10 100 Data rate [Mbit/s] Mobile Communication and Mobile Computing 142 WLAN- Spectrum Allocation HIPERLAN License exempt. 455 MHz HIPERLAN High Speed wireless access Sharing rules 100 MHz U-NII U-NII Unlicensed 300 MHz 5100 5200 5300 5400 5500 5600 5700 5800 5900 Frequency [MHz] U-NII ... Unlicensed national information infrastructure source: www.ist-mind.org, www.3gpp.org Mobile Communication and Mobile Computing 143 Interworking UMTS/WLAN - User should be notified of any possible degradation - subscriber database could be shared, or separated in HLR/HSS (3GPP) or AAA (IETF) format Three classes: - no coupling - loose coupling - tight coupling no coupling UMTS/WLAN as completely independent Pro: - Rapid introduction - no impact on GSN nodes Contra: - poor handover - no common database, billing AAA ... Authentication, authorization, accounting loose coupling UMTS/WLAN use same database in AAA format - good handling - no impact on GSN nodes - poor handover tight coupling HIPERLAN/2 is connected through UTRAN to UMTS, using special interface - improved handover performance - HIPERLAN/2 have to support complete UMTS interface - feasible if operator have both networks Mobile Communication and Mobile Computing 144 Data security in WLAN and UMTS Data security for WLAN: • 802.11i - • WPA - WiFi Protected Access − − − • new, additionally standards 802.11a/h and 802.11g complex solution for security packet encryption key distribution via RADIUS -Remote Access Dial-In User Service packet authentication partial compatibility with IPsec relevant against all attacks preliminary to 802.11i properties similar to 802.11i competition to 802.11i WEP - Wired Equivalent Privacy - additionally to standard 802.11b, partially obsolete!!! users mobility between several AccessPoints, without re-configuration (roaming) disadvantages: - short key of 64 / 128 bit different, partially contradictory statements to offered security Data security for UMTS: • IPsec - Client/Server based, Clients and IPsec-Servers negotiate dynamic keys - tolerant, relevant for key assignment to IP-subnets and against all Internet-attacks - secrecy on the network layer: • IP-datagrams • TCP/UDP-segments • ICMP/SNMP-messages - Encryption via DES, 3DES and 40bit-DES - authentication via - “IP Encapsulating Security Payload" (RFC 2406, 1998) - “IP Authentication Header” (RFC 2402, 1998) Mobile Communication and Mobile Computing HomeRF (Radio Frequency) • • • • competitive standard to IEEE 802.11 Up to 128 network nodes Frequency jump in separations of 3MHz or 5MHz Low costs and support of synchronous services: DECT speech support • 2,4 GHz (FHSS), transition power max. 100 mW, • Shared Wireless Access Protocol (SWAP): – hybrid protocol of DECT (TDMA) and CSMA according to IEEE802.11 (modified) • up to 6 wireless fixed network connections • however sinking market shares in comparison with IEEE 802.11 145 Mobile Communication and Mobile Computing HomeRF • data rate 1-2 Mbit/s • 50 m reach within buildings • Supplier: e.g. Intel with ANYPOINT (wireless home network) • future: – HomeRF + Bluetooth: DUAL MODE SYSTEM (Symbionics) + ad-hoc possibly + voice transmission - today only few manufactures 146 Mobile Communication and Mobile Computing Wireless City Networking via 802.16 IEEE Wireless MAN/ ETSI Hiper MAN 147 Mobile Communication and Mobile Computing Wireless City Networking: scenarios • new IEEE 802.16 standards can provide great regions with fast Internet services • Use fields: – – – – office materials shops cafes at the railway stations to surf at the parks 148 Mobile Communication and Mobile Computing USA: Wireless MAN • Wireless MAN: 802.16-version in USA • Backgrounds: – competition to T-Mobile USA - mobile radio network provider – great number of 802.11-Internet service providers (ISP via Wireless LAN) – wide spread 802.11x – networks in the country – via 802.11 provided approx. 2500 regions 149 Mobile Communication and Mobile Computing Europa: Hiper MAN • ETSI (European Telecommunications Standard Institute): – activities in the range of 802.16 – development of Hiper MAN • new marketable products: since July 2004 (according to announcement of Fujitsu Europe) 150 Mobile Communication and Mobile Computing 802.16 / 802.16a • Wireless MAN Standard 802.16 – – – – – developed end of month January 2003 frequency bandwidth: 10 up to 66 GHz reach: up to 50 km (30 miles) data rate: up to 134 MBit/s new 802.16x standards can provide great regions with fast Internet service, momentary trial operation in Boston/USA (ISP via Wireless MAN) • Start-Standard 802.16a – – – – – – frequency bandwidth: 2-11 GHz reach: up to 50 km (30 miles) data rate: up to 70 MBit/s only predominantly conceptualized for fast links of hotspots can be used to establishment of private DSL-links final operation inset: January 2005 151 Mobile Communication and Mobile Computing 802.16a-Forum • Members: – Airspan Networks, Alvarion, Aperto Networks, Ensemble Communication, Fujitsu of America, Intel, Nokia, Proxim, Wi-LAN • Aims: – to provide compatibility of 802.16a-products among each other 152 Mobile Communication and Mobile Computing 153 Conclusion: 802.16 vs 802.11 802.11 802.16 + advantage: + advantage: – in spite of sharp competition to Mobile Radio (IMT2000/UMTS) 802.11x gained the mass market – well-elaborated 802.11x (x = a, b, c, d, e, f, g, h, i, WPA) − disadvantage: – existing bandwidth problems (at most up to 54 Mbit/s) – reach at most up to 100m without directional antennas – covers approx. 50km (30 miles) – substitution via 802.16 as access techniques possible – in future cost-efficient in comparison to 802.11 − disadvantage: – averaged investment for leased circuits amounting to 1000$ per location necessary – sharp competition to Mobile Radio (IMT2000/UMTS): to occupy the market is for Wireless Networks more important as for Mobile Radio! – final operation inset: planned January 2005 only Mobile Communication and Mobile Computing Better than UMTS: future use scenarios of 802.16 Scenario: fast Internet WWWServer/ Internet (1) via ISDN, Modem, DSL WAN ISP via Wireless MAN PC/LAN (2) via Wireless MAN Access Point WAN Wireless MAN 802.16 up to 50 Km (30 miles) 70-134 Mbit/s Wireless PCs IntranetFirewall 154 Mobile Communication and Mobile Computing Bluetooth 155 Mobile Communication and Mobile Computing Bluetooth - Facts • • • • • • • Harald Bluetooth was the King of Denmark in the 10th century 1998 started from Ericsson, Intel, IBM, Nokia, Toshiba Open Standard: IEEE 802.15.1 Generally for wireless Ad-hoc- piconets (Range < 10m) Goal: not expensive One-Chip-Decision for radio/ wireless communication networks Use fields: – Connection of peripheral devices – Support of Ad-Hoc-Nets – Connection of different networks Frequency band in IMS-Range of 2,4 GHz 156 Mobile Communication and Mobile Computing Bluetooth • Pico nets with up to 8 participants (ad-hoc) (one master, slaves) • Scatter nets as an association of different pico nets • frequency hopping is used for improving of interception safety and system robustness 157 Mobile Communication and Mobile Computing 158 Bluetooth - properties • • Range: - 10 cm up to 10 m at 1 mW transmitting power - up to 100m at 100mW Data rates: – 433,9 kBit/s asynchronous-symmetrical – 723,2 kBit/s / 57,6 kbit/s asynchronousasymmetrical – 64 kBit/s synchronous, voice service – In future up to 20 Mbit/s (IEEE 802.15.3) Basic set-up Bluetooth 2,4-GhzHF BluetoothBasebandController HostSystem Mobile Communication and Mobile Computing 159 Bluetooth-comparison FUNCTION Bluetooth v1.1 IrDA Data 1.1 IEEE802.11 (WLAN) Range w/o PA: 10 meter max. 1 meter max. 50 meter max. Angle: omni-directional ca 30° omni-directional RF Frequency Band: ISM Band, 2.4 GHz Infrared Radiation ISM Band, 2.4 GHz Mobility: mobile stationary mobile Data rate: 721kBit/s 4MBit/s 2MBit/s Security level: High Low High Source: http://www.okisemi.com Mobile Communication and Mobile Computing Bluetooth- functionality Not connected Standby Standby t =2 s connectionstatus Inquiry after unknown Address Page after unknown Address t =0,6 s active states Low-Powerstates Send data PARK MAC-Address resigned connected HOLD SNIFF MAC-Address available 160 Mobile Communication and Mobile Computing 161 Bluetooth – architecture (1) Applications Data Data TCS,SDP,RFCOMM L2CAP HCL connection between Hardware and upper protocol (only necessary, if L2CAP not implemented in Hardware!) LMP connection between end devices In hardware implemented ! Baseband Radio Physical connection interface TCS …Telephony Control Protocol Specification SDP … Service discovery protocol RFCOMM … RF communication protocol (cable replacement protocol) LMP … Link Manager Protocol HCL … Host Controller L2CAP … Logical Link Control and Adaptation Protocol Mobile Communication and Mobile Computing Bluetooth- architecture (2) Radio Layer - work area: ISM-Band (2,4 Ghz) - Spread Spectrum Communication - Frequency Hopping- Technology - high error rate acceptability through CVSD-encoding at heavy micro wave load Baseband - controls Radio- Layer 2 Modes: - Synchronous, connection-oriented transfer (SCO) voice connections need symmetrical, circuit-switched point-to-point-connections, Master reserves two successive time slots (up- and downstream) - Asynchronous, connectionless transfer (ACL) data transfers need symmetrical or asymmetrical, packet-switched point-to-point/multipointtransfers, master uses polling CVSD… Continuously Variable Slop Delta (Sprachkodierung) 162 Mobile Communication and Mobile Computing Bluetooth- architecture Link Manager Protocol 3 Functions - Piconet management - link configuration - security functions Logical Link Control and Adaption Protocol Functions: - Mutiplexing (different applications can use connection between 2 devices simultaneously) - Reduzierung der Paketgröße der Anwendungen auf akzeptable Baseband- Paket- Größe - Quality of Service 163 Mobile Communication and Mobile Computing Possible configurations Master Slave Piconet Scatter net 164 Mobile Communication and Mobile Computing possible configurations Piconet Scatternet Slave 3 Slave 1 Master Slave 4 Master Slave 5 Scatternet Slave 2 Piconet 2 Piconet 1 Bluetooth GSM a) Peer to Peer (or 1 Master and 1 Slave) b) Multi-slave (up to 7 "slaves" with 1 Master) • association of different pico nets • frequency hopping : jumps in k steps (k = 0…22 or 79) with Δf distances in ISM-band 165 Mobile Communication and Mobile Computing Bluetooth - Frequencies Country Frequency range [MHz] Spain 2445 – 2475 France 2446,5 – 2483,5 Japan 2471 – 2497 other Europe / USA 2446,5 – 2483,5 RF channels fk = 2449 + k Δf fk = 2454 + k Δf fk = 2473 + k Δf fk = 2402 + k Δf Multiplier k = 0,…,22 k = 0,…,22 k = 0,…,22 k = 0,…,78 Δf… frequency distance between channels - different frequencies around the world Goal: Harmonization of wavebands Source: http://www.mobileinfo.com 166 Mobile Communication and Mobile Computing 167 Bluetooth - Framestructure Frame fk one Slot Packet 625 µs one slot Single slot frame source: http://www.intel.com fk+1 three3slotSlot-packets Packets Slave Master fk+1 one Slot Packet Slave Master fk Frame one Slot Packet 625 µs one slot Multi slot frame Mobile Communication and Mobile Computing Bluetooth – security - 128 Bit Key encryption and authentication - every device has own 48 Bit- address - over 281 .1012 devices can keep apart - low range (manipulation only local!) PIN PIN E2 E2 Authentication Link Key Link Key E3 E3 Encryption Encryption Key source: http://www.intel.com Encyption Key user input (Initialization) (possible) permanent storage temporary storage 168 Mobile Communication and Mobile Computing Bluetooth – security 169 Generic access: Three modes - non-secure - service level enforced security - link level enforced security For Devices: two modes - trusted - untrusted Bluetooth device initiates security procedures before the channel is established Bluetooth is not secure enough for critical transmissions (billing etc.) for Services: three modes: - services that require authorization and authentication - services that require authentication only - services that are open to all devices Sources: http://www.niksula.cs.hut.fi, Müller T., Bluetooth Security Architecture Mobile Communication and Mobile Computing Bluetooth – applications (1) • replaces perhaps infrared in the area of the coupling of peripherals completely • „Intelligent Shop“ – shop informs the buyer about special offers by mobile phone or handles inquiries for offers in the individual halls • Bluetooth-capable ticket machine – Payment over mobile telephone is carried out without contacts • control of home appliances by mobile telephone • lower layers are developed further in the context of the IEEE 802.15 working group (WPAN - Wireless Personal Area Networks) – higher data rates, further frequencies, but possible interferences with other systems 170 Mobile Communication and Mobile Computing Bluetooth - applications wireless connection Headset Handy 171 Mobile Communication and Mobile Computing 172 HIPERLAN HIPERLAN/1 wireless LAN (as extension to conventional LANs) 5,15 - 5,25 GHz, ca. 20 Mbps, reach > 50 m, mobility < 10m/s decentralized Ad-hoc net, no QoS-guarantee HIPERLAN/2 wireless ATM-LAN (as extension to ATM and IP nets) 5,15 - 5,25 GHz, ca. 20 Mbps, reach 50 m, mobility<10m/s cellular structure with base stations, ATM service classes point-to-multipoint ATM connections 5,15 - 5,25 GHz, ca. 25 Mbps, reach 5000 m, stationary/quasi-stationary, point-to-multipoint, ATM service classes HIPERACCESS HIPERLINK point-to-point ATM connection 17,1 - 17,3 GHz, 155 MBit/s, reach 150 m, stationary/quasi-stationary, point-to-point, ATM source: ETSI RES 10, BRAN Mobile Communication and Mobile Computing Assessment of HIPERLAN • despite of some unique characteristics there are no products available yet, only single prototypes • is planned as one of the alternatives for BRAN (Broadband Radio Access Network) in the Wireless ATM • planned frequencies are originally not worldwide available (5,1-53GHz) 173 Mobile Communication and Mobile Computing 174 Wireless ATM Requirements: • wireless connection of mobile terminals to ATM-networks • compatibility to existing standards • existing networks should be easily upgradeable • guaranteed service quality properties which other wireless nets don't offer • UMTS and WLANs don‘t offer any data rates >50 Mbit/s Problems: • ATM is conceived for high data rates • ATM is optimized on reliable media • applications should notice nothing of the wireless mode Mobile Communication and Mobile Computing Wireless ATM: review • WATM still is standardization endeavors, no definite standards approved • the WATM forum has tried to standardize as much as possible, the WATM standard is relatively complex • WATM supports relatively many configurations: – wireless Ad-hoc networks – wireless mobile end-devices: access to the network via radio subsystem, similar to access-points – mobile end-devices: seamless handover between connected terminals – mobile ATM-Switches (for planes, ships, trains etc.) – fixed ATM-terminals: conventional ATM – fixed terminals with radio access: comparable with line-of-sight radio links • It is not arranged completely for which configuration also products will exist 175 Mobile Communication and Mobile Computing Satellite-based systems 176 Mobile Communication and Mobile Computing Sample system Inter-Satellite Link (ISL) Mobile User Link (MUL) Gateway Link (GWL) User Gateway Ground Station Spot beams Footprint PSTN, ISDN, GSM, ... Internet 177 Mobile Communication and Mobile Computing Basics (1) • satellites describe elliptical or circular orbit around the earth • distance to the earth remains constant: FG m g R / r 2 m r FZ (1) 2 FG - Appeal of the Earth FZ - Centrifugal force m R r g ω f - Mass of the satellite - Earth radius, 6.370km - Distance of the satellite to the Earth’s center - Grounding acceleration, g = 9,81 m/s2 - Angular frequency: 2 f , T 1 / f 2 / - Cycle frequency of the satellite 178 Mobile Communication and Mobile Computing 179 Basics (2) Formulae transformation: • F =m.a • Fgrav = k . M . m / r2 • mg = k . M . m / R2 • k.M • FG (by Newton) (Gravitation between 2 point masses) (Appeal on the Earth surface = Gravitation) = gR2 = gR2 m/r2 = gm(R/r)2 (transformed) • δt = 2 . (r-R) / c Signal propagation delay Satellite r-R Uplink r-R Downlink Mobile Communication and Mobile Computing Basics (3) • (1) resolved to r gives: • that means, the distance of a satellite to the earth's surface depends only on its cycle duration (special case T = 24h - > synchronous distance r=35.786 km) gR 2 r 3 (2) 2 2 f Cycle duration [h] velocity [x1000km/h] 20 12 4 Synchronous distance 35.786 km 10 20 30 40 x 106 m 180 Mobile Communication and Mobile Computing Satellite system classes GEO (Geostationary Earth Orbit) ca. 36 000 km MEO (Medium Earth Orbit) ca. 6000 - 12 000 km HEO (Highly Elliptical Orbit) LEO (Low Earth Orbit) ca. 500 - 1500 km Van-Allen-belts 2000 - 6000 km 15 000 - 30 000 km (no satellite use possible) 181 Mobile Communication and Mobile Computing Geostationary Satellite systems Principle: Satellit Base for Inmarsat Uplink • • • • Downlink Constant position to the Earth, 3 satellites cover complete earth (with the exception of the polar caps), satellites move synchronously to the Earth Simple solution, however large distance (36000 km), therefore high signal propagation delay, long life time of the satellites: ~ 15 years low data rates, large transmission power required problems: – on the other side of the 60th degree of latitude reception problems (elevation) – because of a high transmission power unfavorable for mobile telephones – signal propagation delay too high (0.25 s) 182 Mobile Communication and Mobile Computing LEO- Systems • non-stationary satellites (LEO - Low Earth Orbit) • distance to the earth ~ 500 - 2000 km • shorter signal runtimes (5-10 ms), lower transmission power of the mobile stations sufficing • however more satellites necessary, frequent handover between satellites, approximately all 10 min. • examples: Teledesic, Globalstar • only low transmission power necessary, suitable for mobile phone networks • Disadvantages: – large number is necessary (50 - 200, or more) – fast handovers within satellites are necessary – short life time of the satellites because of atmospheric friction (5-8 years) 183 Mobile Communication and Mobile Computing MEO- Systems • ~ 10000km, lower number of satellites necessary : ~12 • slow movement: handover between satellites is hardly necessary • cycle duration: 6h • high elevation enables coverage large, highly-populated areas • Problems: – signal propagation delay: 70 to 80 ms – higher transmission power is necessary – special antennas for small cells are necessary 184 Mobile Communication and Mobile Computing Service transitions in Inmarsat-C-service Inmarsat Satellite 600 bit/s 185 L-Band 1,5/1,6 GHz Rx/Tx (GPS) laptop 600 bit/s Inmarsat - C – End-Terminal Graphic table Terrestrial station X.25 Buffer memory Interface Phone-Interface Mail Box X.25 Net modem TelefaxInterface FaxInterface Email System PAD Internet Fixed network data + maps laptop text fax desktop data + maps desktop Email desktop Mobile Communication and Mobile Computing 186 Examples of satellite-based systems Satellites Height Data rate Teledesic (planned) 288 (?) ~ 700 km 64 Mbit/s 2 / 64 Mbit/s Iridium 66 (+6) ~ 780 km 2,4 / 4,8 kbit/s Globalstar 48 (+4) ~ 1400 km 9,6 kbit/s ICO 10 (+2) ~ 10 000 km 4,8 kbit/s Inmarsat 5 geostationary 2,4 kbit/s Orbcomm 35 LEO-stationary 57,6 kbit/s Globalstar can transfer bi-directionally up to 144 Kbit/s, through combination of channels Orbcomm - first commercial LEO–service worldwide http://Globalstar.com/ Mobile Communication and Mobile Computing 187 Comparison of satellite-based systems Satellite-based system GEO MEO LEO Distance, km r = 35.786 km r-R=6000 – 12000 km r-R= 500 – 2000 km Cycle duration, T 24 h 6h 95 – 120 min Signal propagation delay, t 0.25 s 70-80 ms 10 ms Transmission power, W 10 5 1 Use examples Numerous systems, approx. 2000: •Sputnik (1957) •Intelsat 1-3 (1965, 1967, 1969) •Marisat (1976) •Inmarsat-A (1982) •Inmarsat-C (1988) ICO 10+2 •Iridium (bankrupt, 2000) 66+6 •Globalstar, 48+4/ 144 kBit/s •Teledesic (2003), 288/ 2-64 MBit/s • Orbcomm, 35 Data rate, kBit/s 0.1 – 1 10 1 – 64000 Life time, years 15 10 5-8 Mobile Communication and Mobile Computing Global Positioning System, GPS 188 Mobile Communication and Mobile Computing Overview • 24 satellites on the 6 orbits (20200 km, time of circulation = 12h) • 5 earth stations (Hawaii, Ascension Island, Diego Garcia, Kwajalein, Colorado Springs) • Accuracy: – so called P-Code for military applications: on ~6m accurately, partially 2,8m – so called Selective Availability Mode, SAM (artificial degradation) for civil applications: < 100m (1.5.2000 disestablished) • Functionality principle: Triangulation • GPS-receiver calculates distance to the satellite on the base of Time of Arrival of the received signals • distances to at least three satellites enables the calculation of position, a fourth satellite can be used for determination of elevation over zero • official initiation 1995, testing since 1978 189 Mobile Communication and Mobile Computing Principle: TOA (Time of Arrival) / TDOA (Time Difference of Arrival) Distance d, Signal Delay T • • • • • Mobile Object synchronized clocks measurement of signal delay by speed of light between satellite and receiver, for instance T = 100 ms hence calculation of distance: d = T • c = 1 • 10-1s • 3 • 108 m/s = 3 • 107 m = 30.000 km calculation of spheres around each satellite the position is on the intersection point of three spheres 190 Mobile Communication and Mobile Computing Principles • satellites send a signal composed of three components 50 times per second: – identification component: PRC (Pseudo Random Code), provides satellite recognition and status information – position component: exact position of satellite – time component: time point, when signal is transmitted • the time offset measured by the receiver is corresponding to the Time of Arrival, from TOA the distance is calculated • for measurement of TOA of signals very accurate clocks are required • the exact position of the satellites must be known 191 Mobile Communication and Mobile Computing Sources of errors Clocks • highly accurate atom clocks in the satellites • simple clocks in the receivers are calibrated via measurement of a fourth satellite Satellite position • satellite orbits are relatively stable and forecastable • deviations are measured by US DoD • deviations are transmitted as correction factor to the satellites using the PRC Miscellaneous error sources • atmospheric faults • multi-path propagation 192 Mobile Communication and Mobile Computing Differential GPS, DGPS • use of a stationary receiver as reference • position of this receiver is exactly known • the stationary receiver carries out position determination and calculates correction factor from the actually obtained position on the base of deviations • correction factor is delivered to the mobile receiver 193 Mobile Communication and Mobile Computing DGPS accuracy grades • Accuracy under 10cm: – professional applications, for instance is interesting in meterology and respectively for user of wellengineered software decisions (machine control systems etc.) • Accuracy under 1m: – events mapping, control of machines, traffic control systems, agriculture • Guaranteed accuracy under 10m: – agriculture/ forestry, railway (wagon search service), car navigation (private/commercial) 194 Mobile Communication and Mobile Computing Galileo • EU-Project for installation of European satellite navigation system • initiation: prospective 2008 • positioning accuracy: 45cm • 30 satellites • Approx. costs: 3,2 Billion € 195 Mobile Communication and Mobile Computing Galileo 196 „ A system that both competes with and complements the American GPS system “ ITS (Intelligent Transport System) •based on a constellation of 30 MEO-satellites •ground stations providing information concerning the positioning of users •in many sectors usable: ─transport (vehicle location, route searching, speed control, etc.) ─social services (e.g. aid for the disabled or elderly) ─the justice system ( border controls) ─public works (geographical information systems) Mobile Communication and Mobile Computing Galileo architecture Service centres GALILEO GLOBAL CONTENT Regional Components 197 Local Components MEO Constellation ... BSS network Local MS s-band . . i-band i-band BSS network GEO RMS network EGNOS Data link s-band . . TTC Local MS OSS Network Data link OSS Network Integrity determination Navigation control & constellation management &dissemination I-Band- NAV UMTS UHF- S&R External complementary systems COSPAS-SARSAT ground segment User segment Mobile Communication and Mobile Computing Broadcast Systems, Distribution Networks 198 Mobile Communication and Mobile Computing 199 Overview • special variants of asymmetric communication systems • HSCSD supports for instance asymmetric connections regarding to data rate, also ADSL • WWW is the biggest representative of asymmetric communication: – data volume of uplink (URLs) is much lower than downlink (complete HTML-pages) • Problem of distribution systems: Sender can be optimized for a large quantity of receivers only, for instance videostreaming • Examples: – DVB, Digital Video Broadcast – DAB, Digital Audio Broadcast Mobile Communication and Mobile Computing 200 Principle of Distribution Systems C C C Time information sequence is optimized for expected access behavior of all consumers t C B B B A A Individual access sample of diverse consumers can more or less deviate from expected access behavior Mobile Communication and Mobile Computing Digital Audio Broadcast, DAB • Audio-transmission in CD-Quality • Non-sensible towards interferences of multi-path-propagation • Use of SFN (Single Frequency Network) – i.e. all senders of some broadcast-program are working on the same frequency as a rule • Frequencies: UHF,VHF, for instance: 174-230 MHz, 1452-1492 MHz • Modulation methods: DQPSK (Differential Quadrature Phase Shift Keying) • Optionally COFDM (Coded Orthogonal Frequency Division Multiplexing) is used with several carrier frequencies inside some DAB-channel (its quantity is between 192 and 1536), 1,5MHz bandwidth for each channel • FEC (Forward Error Correction)-mechanism for fault correction • Up to 6 stereo-programs by 192 kbit/s in the same frequency band are transmittable • alternatively data can be transmitted with up to 1,5 Mbit/s (responding to the used code rate etc.) 201 Mobile Communication and Mobile Computing Digital Audio Broadcast, DAB 2 Transport Mechanisms • Main Service Channel (MSC): – Data, Audio, Multimedia – 2 Transport Modes: Stream Mode, Packet Mode • Fast Information Channel (FIC): – Transport of Fast Information Blocks (FIB, 32 Byte) – control data for interpretation of Data in the MSC, can be also used for services such as Traffic Dispatches, Paging etc. • • • • Audio-converting: PCM 48 kHz & MPEG2-Audiocompression High transmission rates by high velocities, up to 250 km/h, responding to distance from sender and error security class, use for instance in highspeed train MOT (Multimedia Object Transfer) protocol for data transmission Cyclic repeat and caching of data blocks 202 Mobile Communication and Mobile Computing Dynamic channel reconfiguration for DAB Ensemble-Configuration Audio 1 192 KBit/s Audio 2 192 KBit/s Audio 3 192 KBit/s Audio 4 160 KBit/s Audio 5 160 KBit/s Audio 6 128 KBit/s PAD PAD PAD PAD PAD PAD Data D1 Data D2 Data D3 Data D4 Data D5 Data D6 Data D7 Data D8 Temporarily changed Ensemble-Configuration Audio 1 192 KBit/s Audio 2 192 KBit/s Audio 3 128 KBit/s Audio 4 160 KBit/s Audio 5 160 KBit/s PAD PAD Audio 7 96 KBit/s Audio 8 96 KBit/s PAD PAD PAD PAD Data D1 Data D10 PAD Data D2 Data D3 Data D11 Data D4 Data D5 Data D6 Data D7 Data D8 203 Mobile Communication and Mobile Computing DVB - Digital Video Broadcasting • • • • • • • • 1991 ELR (European Launching Group) founded Goal: joint digital Television System for Europe Specifications: DVB-S, DVB-T, DVB-C Frequency reaches: 200, 550, 700 MHz Cell size: up to 60 km Used data rate: ~38,5 Mbit/s Velocity of mobile stations: up to 200 km/h Central Unit: combined DVB-Receiver-Decoder (set-top-box) – can receive DVB-Data via satellites, B-ISDN, ADSL… – some transmission systems offer a feedback channel for Video on Demand etc. 204 Mobile Communication and Mobile Computing DVB - Digital Video Broadcasting • Different Quality Levels defined: – SDTV (Standard Definition TV) – EDTV (Enhanced DTV) – HDTV (High DTV) • Data transport: – User Data: MPEG2-Container (Data Transfer Unit) like DAB, Container doesn’t define the type of data • Service Information about MPEG2-Container-content: – NIT (Network Information Table): Information from a provider about offered services and optional data for the receiver – SDT (Service Description Table): Description and parameters for each service in the MPEG2-stream – EIT (Event Information Table): Data about actual transmission status – TDT (Time and Date Table): e.g. updating of DVB-receiver 205 Mobile Communication and Mobile Computing Possible contents of DVB/MPEG2-Container MPEG2/DVB-Container MPEG2/DVB-Container HDTV EDTV Single channel (High Definition TV) MPEG2/DVB-Container Several channels (Enhanced DTV) MPEG2/DVB-Container SDTV Several channels (Standard TV) Multimedia (data broadcasting) 206 Mobile Communication and Mobile Computing DVB used as medium for asymmetric Internet-access • • • Client sends data query to Provider, Provider transmits data to the satellite network, receiver obtains data via DVB-receiver Feedback channel can be phone network, for on-demand services Data rates: – 6 up to 38 Mbit/s downlink, 33 kbit/s up to over 100 kbit/s (ADSL) uplink • Advantages: – data can be transmitted in parallel with TV – no additional costs for satellite provider – low priced for low-density populated areas • Disadvantages: – all users need satellite antennas – only a minor part of the total bandwidth is usable – not suitable for high-density populated areas 207 Mobile Communication and Mobile Computing DVB as medium for the asymmetric Internet-access Satellite provider DVB– Card in the PC dedicated line (user-to-user) Internet Content Provider Service Provider 208 Mobile Communication and Mobile Computing 3. Mobile Computing 209 Mobile Communication and Mobile Computing Layer 3 Mobile IP v4 & v6 DHCP 210 Mobile Communication and Mobile Computing Mobile IP (Internet Protocol) 211 Mobile Communication and Mobile Computing Problem situation • computer mobility in heterogenic networks • relocation between different IP-subnets • Goal: transparent migration and localization, compatibility to IP, no changes of existing routers • Idea: introduction of temporary/ actual IP-addresses (also “care-of-address”, COA); • mapping of permanent to temporary IP-addresses using localization technique 212 Mobile Communication and Mobile Computing 213 Requirements to MobileIP according to IETF Transparency: – mobile computer is permanently reachable via its previous “home-address” – can change its network access point freely – can also communicate after coupling/uncoupling Compatibility: – supports each layer below IP (also 1 & 2) – mobile computer can also communicate with each “nonmobileIP”-computer – no changes to existing computer/routers Security: – all registering messages must be authenticated Mobile Communication and Mobile Computing IETF Mobile IP Goals/Restrictions Minimization of overheads: – mobile connections are possibly wireless and have limited band width – mobile connections have possibly higher error rate Efficiency and scalability: – support of a large quantities of mobile computers – support of a theoretically Internet-wide mobility 214 Mobile Communication and Mobile Computing Architecture model 215 Foreign Agent (FA) Foreign Subnet Global Internet Mobile Node Anywhere Home Subnet Home Agent (HA) Router Correspondent Node (CN) Mobile Communication and Mobile Computing Terms Mobile Node (MN) with permanent IP-address from Home Subnet Home Address permanent address of a mobile computer Home Agent (HA) with knowledge of actual residence of all MNs from so called Home Subnet, like GSM-HLR Care of Address temporary address of a mobile computer from Foreign Subnet Foreign Agent (FA) for assignment of temporary IPaddresses (care of address) and packet forwarding to MNs currently residing in its subnet 216 Mobile Communication and Mobile Computing Log on via Foreign Agent Foreign Subnet HA Home Subnet FA MN • • Log on with a FA - Care-of Address (address of FA, is just an intermediate target for all MN- related packets, tunnel-end) or Application of a co-located Care-of Address (address from Foreign-Subnet, MN is tunnel-end itself), but reception of an Agent Advertisement Message with a set “R”-bit, i.e. the MN is forced to log on with FA itself, although it can operate autonomously 217 Mobile Communication and Mobile Computing 218 Log on by Home Agent directly • MN uses co-located Care-of Address • MN is returned to Home Network and would like to log on/off itself with the HA Authentication: Home Subnet MN • each mobile entity (MN, HA, FA) must be able to support a “mobility security association”, which is indicated via IPaddress and SPI (Security Parameter Index). • Mobile IP provides three different Authentication Extensions: • Mobile - Home Authentication Ext. • Mobile - Foreign Authentication Ext. • Foreign - Home Authentication Ext. HA Mobile Communication and Mobile Computing Addressing Problem: For the receivers 2 addresses are necessary (permanent and temporary IP-address respectively home address and COA) Methods of resolution: • Encapsulation – IP in IP, standard method in MobileIPv4 – minimal Encapsulation • IP-Option (not supported by all implementations) 219 Mobile Communication and Mobile Computing IP in IP Encapsulation OUTER IP HEADER IP HEADER IP HEADER IP PAYLOAD IP PAYLOAD • IP-source/target address of external/outer IP-Header defines the “end- points” of the tunnel • IP-source/target address of internal IP-Header represents the actual packet sender respectively receiver • Internal IP-Header isn't changed using “Encapsulator” (exception: TTL) 220 Mobile Communication and Mobile Computing 221 Routing (unicast) • Mobile Node: – in Home Network it operates like each other Node – in Foreign Network it must search a Default Router using the following rules: • FA COA: – ICMP Router Advertisement-Part; – IP-source address of Agent Advertisements (lower Prior.) • co-located COA: ICMP Router Advertisement for this address • Foreign Agent: – FA must check by reception of tunneled packets whether internal target address corresponds with one of the IP-addresses of Visitor List – FA must route the received packets of registered MN’s! Mobile Communication and Mobile Computing Routing (unicast) II • Home Agent: – HA must intercept each packet for absent MN – in addition IP-target address of each incoming packets is verified – if MN has no mobile coupling presently, the packets sent to it must not be intercepted, MN is situated in Home Subnet and accepts packets itself or is off-line 222 Mobile Communication and Mobile Computing 223 Routing (necessities) • ARP (Address Resolution Protocol): – oriented to resolution of IP-addresses in physical (Hardware, Link Layer) addresses (Ethernet: MAC-addresses of controllers) • Proxy ARP: – Proxy ARP-reply is an ARP-reply, which can be sent instead of a host A by other host B (with its hardware address) – Hosts, receiving this reply, associate the hardware-address of node B with the IP-address of node A and send future packets for A to B • Gratuitous ARP: – is an ARP-reply, which is sent from a host, to force other hosts to update the records in their ARP-Caches – this ARP-reply contains the IP-address, which should be changed in the ARP- Caches, as well as the hardware address which should be updated Mobile Communication and Mobile Computing Routing - Scenario • MN leaves Home Network • MN decides to register FA Care-of Address • Before Registration Request: MN re-sets a reaction on future ARP-requests • Registration Request • contains and accepts HA Request, implements Gratuitous ARP (IP-address MN ===> own hardwareaddress) and uses Proxy ARP to respond to ARPrequests corresponding to MN hardware address 224 Mobile Communication and Mobile Computing Triangle Routing FA CN CN ===> MN: Foreign Network HA MN Home Network although CN is in the same Subnet like MN, packets are routed respectively tunneled via FA and primarily HA (possibly over half of terrestrial globe)!!! MN ===> CN: Be routed conventionally via Default Router Special case: Routing (MN & CN are in the same Subnet) Relief (IPv4): Route Optimization 225 Mobile Communication and Mobile Computing Optimizations: Routing Terms: • Binding Cache: table with Mobility Bindings of MNs (on CN, can tunnel itself now) • Binding Update: message, contains up-to-date Mobility Binding of a MN, particularly the Care-of Address Procedure: • Update of Binding Caches • Control seamless Handoffs between FA‘s 226 Mobile Communication and Mobile Computing 227 Updating of Binding Caches • Binding Cache of a CN: Care-of Address of one/several MN‘s, with respective Lifetime • No Entry: non-optimal Routing, BUT: HA doesn’t only tunnel a datagram from CN, but also sends a Binding Update to it • CN should generate/change Binding Cache-Entry only then, when trusted Mobility Binding received (Bind. Upd.) for corresponding MN (ergo: Secure CN <===> HA) • If FA receives tunneled Packet for a MN that is no longer in Visitor List, then it must care that corresponding CN receives a Binding Update (Binding Warning to HA) Mobile Communication and Mobile Computing 228 Smooth Handoff between FAs • Problem of Basis-MobileIP: MN is with a new FA, but the packets tunneled to old FA will be lost • FA Smooth Handoff: MNs are informed via new FA (packet can be forwarded) • also Packets of hosts with non-up-to-date entries in Binding Cache can be forwarded now from old FA to the new FAs • Previous Foreign Agent Notification Extension enables to prompt the new FA to inform the old FA (Binding Update Message) Mobile Communication and Mobile Computing MobileIP v4 & v6 in comparison Mobile IPv4 Routing Bottle neck Security Mobile IPv6 Optimal Routing, only if MN in the Home Network. (Otherwise non-efficient „Triangle“-Routing) Optimal Routing is generally possible, if CN knows the Care-of Address HA is a possible bottleneck, because all traffic to the MN is processed over it HA is load essentially reduced, because CN‘s can just directly communicate with mit MN‘s Authentication is prescribed only by Registration and then also between HA and MN only Authentication and encryption are possible anywhere, because they are supported from IPv6 Robustness Used FA‘s / HA‘s must not be off-line Performance No good performance due to IPv4-requirements and non-optimal Routing Short-time failure/re-configuration of HA is mastered thanks to Automatic Home Agent Discovery. IPv6 is essentially simpler to upgrade, therewith also Mobile IPv6 Essentially better due to requirements from IPv6 (uniform Headers, less Overheads) and optimal Routing 229 Mobile Communication and Mobile Computing Assessment • Mobile IP enables the unlimited accessibility/roaming of mobile computers using perpetuation of their addresses and step-less transfer between subnets • Particularly necessary for applications without “pull”semantics (for instance, distributed applications with mobile users, videoconferences, VoIP) • Keeping of permanent addresses are also important corresponding to Firewalls etc. in the case of call semantics • Successive availability in the form of products 230 Mobile Communication and Mobile Computing 231 Dynamic Host Configuration Protocol (DHCP) Properties: • permits automatic configuration (IPaddress, subnet-mask, router, DNS-Server, ...) and therewith integration of (mobile) computers • Client/Server-Model • Lease Concept • Relevant for management of Careof-Addresses Server A Client Determination of configuration Server B Determination of configuration Selection of a configuration Confirmation of configuration Mobile Communication and Mobile Computing DHCP Assessment • no secure mechanisms standardized • no standardized communication (signalization, for instance information exchange about managed address areas) between DHCPservers • good base for allocation of co-located COAs in MobileIP 232 Mobile Communication and Mobile Computing IPsec: Network security 233 Mobile Communication and Mobile Computing IPsec: Security on the network layer (1) • IPsec - IP Security Protocol – new developed protocol from TCP/IP-Stack, related to the IPng - Group • IPsec uses: – encryption services -> DES, TripleDES and 40-bit-DES between hosts at a VPN (virtual private network) – specification for Internet Key Management Protocol (IKMP), based on ISAKMP/Oakley (1998, Internet Security Association and Key Management Protocol - ISAKMP) • IPSec-tunnels – encapsulation of TCP/IP-data via the ESP/AH- headers: – Developed by S.Kent, R. Atkinson „IP Encapsulating Security Payload" (RFC 2406, 1998) and "IP Authentication Header" (RFC 2402, 1998) – relevant for key assignment to IP-subnets 234 Mobile Communication and Mobile Computing IPsec: Security on the network layer (2) • Secrecy on the network layer: a sending host encrypts/authenticates data encapsulated in the IP-datagrams – TCP/UDP-segments – ICMP/SNMP-messages • Authentication on the network layer: – target host can authenticate source IP-addresses • Basic protocols: – Authentication Header (AH) Protocol – Encapsulation Security Payload (ESP) Protocol • AH and ESP both requires target and source Handshake-Routine: – establishment of a logical channel via network layer, called Service Agreement (SA) – each SA is unidirectional • Distinctly determined via: – security protocol (AH / ESP) – source IP-address – Con-ID of 32 Bit 235 Mobile Communication and Mobile Computing 236 Encapsulation Security Payload (ESP) Protocol • • • • offers secrecy, host authentication and data integrity data, ESP trailers encrypted next header field is a trailer in the ESP ESP- authentication field is similar to AH- authentication field; protocol field = 50 authenticated encrypted IP-Header ESP-Header TCP-/UDP-Segment Protocol = 50 ESP-Trailer ESP-Auth Mobile Communication and Mobile Computing Authentication Header (AH) Protocol • offers host authentication and data integrity, but no secrecy • AH headers inserted between IP-Header and IP-data field; protocol field = 51 • participated routers process datagrams as usually AH-Header consists of: • Con-ID • authentication data: signed message digest calculated via original IP-Datagram, offers authentication of source hosts and data integrity • next header field is specific data type (TCP, UDP, ICMP etc.) IP-Header AH-Header Protocol = 51 TCP-/UDP-Segment 237 Mobile Communication and Mobile Computing Layer 4 238 Mobile Communication and Mobile Computing Problems of conventional protocols Problem: • Loss of packets on the radio channels with higher biterror rate (BER) results in frequent retransmissions of packets and therewith in further efficiency loss • TCP-Protocol uses so called “Slow-Start”-mechanisms: window size is reduced by significant packet losses; this is reasonable for fixed networks, to react on overload, but not for packet losses due to higher BER • limited suitability of conventional transport protocols for mobile communication! 239 Mobile Communication and Mobile Computing Conventional protocols Congestion Control: • packet loss as a rule, in fixed networks occurs only by overload of several components • reducing of transmission rate Slow Start: • sender calculates a traffic window size • start with window size 1 • exponential growth till to Congestion Threshold • then linear growth Fast Retransmit / Fast Recovery: • If ≥ 3 DUPACK (duplicate ACK) are received -> sender informs about packet losses and repeats missing packets 240 Mobile Communication and Mobile Computing Resulting problems in mobile environment • packet losses due to transmission errors are wrongly interpreted as traffic jam (Congestion)! • > Slow Start is also wrong • > Ideally the packets lost due to transmission errors are simply repeated (no effects on Congestion Control) • great variances of Round-Trip-Time 241 Mobile Communication and Mobile Computing Scenario Access Point 1 Mobile Host Access Point 2 Fixed Host 242 Mobile Communication and Mobile Computing Solutions Sender- transparent: • to hide the packet losses transparent to the sender • transmission repeat via Access Point – on layer 2 – on TCP-layer Wireless-aware sender: • sender understands the reason of packet loss • explicit notification of senders • sender tries to determine the reason of loss Where will be the modifications carried out?: • only by the sender • only by the receiver • only on the transient node (Access Point) • combinations 243 Mobile Communication and Mobile Computing Solution “Split Connection“ 244 – Separation between transport functionality in the fixed network respectively in the mobile network: Workstation TCP Fixed network MSR Mobile TCP Mobile network Mobile node Mobile Support Router TCP-Handover by relocation of mobile node MSR – MobileTCP is specially optimized (up to 100% of efficiency improvement possible) – system-internal TCP-Handovers are necessary, however transparent for fixed computer (Workstation) Mobile Communication and Mobile Computing Example of I-TCP (indirect TCP) • • • • • separation of TCP-connection at the Access Point optimized TCP over the wireless Link (not absolutely necessary) no changes of TCP for the fixed network transparent for Fixed Host loss of End-to-End-semantics Access Point 1 Mobile Host „wireless TCP“ „standard TCP“ Fixed Host 245 Mobile Communication and Mobile Computing Example of I-TCP • Mobility: status and buffer transfer Fixed Host Access Point 1 Mobile Host Access Point 2 246 Mobile Communication and Mobile Computing I-TCP Assessment + + + + + ─ ─ ─ ─ no changes in the fixed network the errors in the wireless part aren’t propagated to the fixed network both parts can be optimized independently relatively simple: „wireless TCP“ concerns one Hop only the properties of wireless networks (bit-error rate, delay time) are known, therefore fast retransmissions are possible loss of End-to-End-semantics additional costs (computation time, storage place) concerning the Access Point high delay times with handover caused by buffering of data by Access Point IT-security mechanisms must be adapted 247 Mobile Communication and Mobile Computing Example of Snoop • • • • transparent extension of Access Point from sender’s viewpoint Access Point listens to the traffic (snoops) and filters the ACKs buffering of data, are sent to the mobile computer after losses of packets in the wireless network a direct retransmission takes place between Access Point and Mobile Host • Access Points send NACK after packet losses of MH Access Point 1 Mobile Host „local retransmission” TCP Buffer Fixed Host 248 Mobile Communication and Mobile Computing Snoop Assessment + + + + maintenance of End-to-End-semantics modifications only at the TCP-Stack of Access Points errors in the wireless part can be corrected locally Soft State + no status transfer at new Access Point is necessary + change is possible, also if the new Access Point possesses no Snoop • no complete transparency of wireless connection • handling of NACK requires the modifications of MH • IT-security: encryption can prevent an access to TCP-Header (most of the up-to-date approaches use End-to-End-encryption!) 249 Mobile Communication and Mobile Computing Higher Layers and Services 250 Mobile Communication and Mobile Computing Wireless Application Protocol WAP Based partially on the materials of WAP-Forum 251 Mobile Communication and Mobile Computing WAP – Standard Overview • Goal: Fusion of Internet-Technologies and mobile radio, creation of new innovative services • standardized by WAP-Forum (http://www.wapforum.org), initiated by Ericsson, Nokia, Motorola • specifies application environment and protocols for mobile end-devices such as radio phones, PDAs, pagers 252 Mobile Communication and Mobile Computing Why WAP? • Mobile radio networks and mobile phones possess special properties and requirements – Display: sizes and presented colors, numerical keyboard, lower processor performance and storage capacity ... – Networks: low data rates, high delays and costs • WAP offers the use of several carriers – TCP/IP, UDP/IP, USSD, SMS, ... USSD - unstructured supplementary service data (GSM) SMS - short message service (GSM) 253 Mobile Communication and Mobile Computing Why WAP ? • • • • WAP-architecture has a modular organization the modules build together a complete Internet-protocol-stack WML-contents can be queried by HTTP-request-messages WAP uses XML (eXtensible Markup Language)-Standard as well as optimized contents and protocols • user interface of conventional end-devices is supported by WML-components – enhances acceptance by users • WAP uses conventional HTTP-Servers – existing development strategies are applicable in the future (common gateway interface - CGI, active server pages - ASP, netscape server API - NSAPI...) 254 Mobile Communication and Mobile Computing 255 Why HTTP/HTML doesn’t suffice? Big pipe - small pipe syndrome Internet <HTML> <HEAD> <TITLE>NNN Interactive</TITLE> <META HTTP-EQUIV="Refresh" CONTENT="1800, URL=/index.html"> </HEAD> <BODY BGCOLOR="#FFFFFF" BACKGROUND="/images/9607/bgbar5.gif" LINK="#0A3990" ALINK="#FF0000" VLINK="#FF0000" TEXT="000000" ONLOAD="if(parent.frames.length!=0)top.location='htt p://nnn.com';"> <A NAME="#top"></A> <TABLE WIDTH=599 BORDER="0"> <TR ALIGN=LEFT> <TD WIDTH=117 VALIGN=TOP ALIGN=LEFT> HTTP/HTML <HTML> <HEAD> <TITLE >NNN Intera ctive< /TITLE > <META HTTPEQUIV= "Refre sh" CONTEN T="180 0, URL=/i ndex.h tml"> Mobile radio networks WAP <WML> <CARD> <DO TYPE="ACCEPT"> <GO URL="/submit?Name=$N"/> </DO> Enter name: <INPUT TYPE="TEXT" KEY="N"/> </CARD> </WML> Converting to binary format 010011 010011 110110 010011 011011 011101 010010 011010 Mobile Communication and Mobile Computing WAP-overview WAP-standard defines: • Environment = Wireless Application Environment (WAE) – – – – – WML (Wireless Markup Language) micro-browser WMLScript virtual machine WMLScript standard library Wireless Telephony Application (WTA) Interface Contents = WAP Content Types – – – – Wireless Session Protocol (WSP) Wireless Transaction Protocol (WTP) Wireless Datagram Protocol (WDP) Interface definitions for mobile network • Layer architecture 256 Mobile Communication and Mobile Computing 257 Comparison: Internet/WWW and WAP Internet Wireless Application Protocol HTML JavaScript Wireless Application Environment (WAE) other services and applications Session Layer (WSP) HTTP Transaction Layer (WTP) TLS - SSL Security Layer (WTLS) Transport Layer (WDP) TCP/IP UDP/IP Carrier: SMS USSD GPRS CDMA CDPD etc.. SMS - Short Message Service (GSM), GPRS - General Packet Radio Service (GSM II+), CDMA - Code Division Multiple Access, CDPD - Cellular Digital Packet Data Mobile Communication and Mobile Computing Wireless Application Environment - WAE • environment for distributed applications with specific reference to low-performance end-devices with limited operation comfort and mobile radio networks • Goals: – – – – network-independent application environment optimized for application in mobile radio systems Internet, i.e. WWW–programming model high interoperability level 258 Mobile Communication and Mobile Computing WAE – abstract network architecture WSP/HTTP Request {URL} Client Gateway Network Application WSP/HTTP Reply {Content} 259 Mobile Communication and Mobile Computing Constituents • Architecture – Programming model – Browser, Gateway, Content Server • WML – as page markup language • WMLScript – as scripting language • WTA – offers access to phone services • Content formats – sets free-defined formats: bitmaps, phonebook records, dates ... 260 Mobile Communication and Mobile Computing Options • User Agent Profiling – to user, end-device, ... adapted contents • Push-model – network initiates delivery of contents • Options for performance improvement – Caching, ... 261 Mobile Communication and Mobile Computing 262 Sample: WAP-Gateway WMLScript WTAI etc. WAP Gateway WAE User Agent WML Web Server WML Encoder WSP/WTP WMLScript Compiler Protocol adapter HTTP CGI Scripts etc. Contents WML Decks, WML-Script Client Mobile Communication and Mobile Computing Sample: WAP - Application Server Client WTAI etc. WML Encoder WSP/WTP WMLScript Compiler Protocol adapter Application logic Contents WML Decks, WML-Script WMLScript WAE User Agent WML WAP Application Server 263 Mobile Communication and Mobile Computing Wireless Markup Language - WML(1) • HTML-like page markup language – different font styles are available, tables and graphics too, but limited • based on W3C-XML • uses HTML and HDML-elements • Deck/Card-metaphor – interactions-/selection possibilities are separated in Cards – navigation (anchor: #) takes place between Cards – Deck-stack corresponds to a WML-file HDML - Handheld Device Markup Language, W3C - World Wide Web Consortium, XML - eXtensible Markup Language 264 Mobile Communication and Mobile Computing Wireless Markup Language WML(2) • explicit navigation model between Decks – Hyperlinks – Events from user interface – History • variables and status-management – variable status can tell about validity of a stack 265 Mobile Communication and Mobile Computing WML– text styles <wml> <card id=“Card1” title=“Text Styles”> <p align="left"> <i>italic</i>, <b>bold</b>,<br> <big>big</big>, <small>small</small>, <u>underlined</u> </p> </card> </wml> Card Deck 266 Mobile Communication and Mobile Computing WML-example (1) <wml> <card id=„Card1" title=„Currency" newcontext="true"> <p> Amount: <input format="*N" name=„amount" title=„Amount:"/> From: <select name=“from“ value=" USD“ title=„From:"> Variables <option value="EUR">Euro</option> ... <option value="USD">US Dollar</option> Selected </select> input To: <select name= ... <br/> = <u>$(conv)</u> <do type="accept" label=„Calculate"> <go href=“bsp.wmls#convert('conv', Script call '$(from)','$(to)',$(amount))"/> </do> <do type="help" label="Help"> <go href="#card1_help"/> Navigation </do> </p> </card> ... 267 Mobile Communication and Mobile Computing WML-example (1): Processing 268 Mobile Communication and Mobile Computing 269 WML-example (2) <card id="card1_help" title="Help"> <onevent type="onenterforward"> Events <go href="bsp.wmls#getInfoDate('date')"/> processing </onevent> <p> Currency exchange rates stem from Federal Reserve Bank of New York and are from $(date). <do type="prev" label=„Back"> <prev/> </do> </p> </card> </wml> Mobile Communication and Mobile Computing WMLScript-overview (1) • scripting language, similar to JavaScript – procedures, loops, conditions, ... – optimized for devices with low storage capacity and CPU-performance • integrated with WML, enables: – – – – reducing of network workload validation of inputs access to vendor-specific APIs programming of conditional logic 270 Mobile Communication and Mobile Computing WMLScript-overview (2) • Bytecode-based Virtual Machine – stack-oriented design – ROM-able – designed with regard to simple, less work-expensive implementation • Compiler in network – better utilization of network capacity and end-device storage • Standard library – basic functionality for processing of strings, URLs, ... 271 Mobile Communication and Mobile Computing WMLScript-example extern function getInfoDate(varName) { WMLBrowser.setVar(varName,„June,3,2002"); WMLBrowser.refresh(); } extern function convert(varName,from,to,amount) { var multiplier = 0.0; ... if (from == „EUR") { ... if (to == „EUR") multiplier = 1.0; else if (to == „RUR") multiplier = EUR_RUR; ... } else if ... WMLBrowser.setVar(varName,returnString); WMLBrowser.refresh(); } Procedures Variables Statements 272 Mobile Communication and Mobile Computing Wireless Telephony Application WTA (1) • offers mechanisms for applications in field of telephony • primary focus: operators/providers and vendors • security and trust are the emphasis • WTA Browser – using improvements of standard WML/WMLScriptbrowsers – own interface WTAI (... Interface) 273 Mobile Communication and Mobile Computing Wireless Telephony Application WTA (2) • WTAI contains: – call control, messaging, interface to phonebook, events processing... • own Client/Server-interaction model – event signalization... • security via separation – browser and port separated • WTAI in WML and WMLScript available 274 Mobile Communication and Mobile Computing WAE content formats • WAE defines uniform formats – visit cards, so called IMC vCard Standard – dates, IMC vCalendar Standard – graphics, WBMP (Wireless BitMaP) – compiled WML, WMLScript • Goal: Interoperability IMC - Internet Mail Consortium 275 Mobile Communication and Mobile Computing WAP layer architecture Wireless Session Protocol (WSP) Wireless Transaction Protocol (WTP) Wireless Transport Layer Security (WTLS) Wireless Datagram Protocol (WDP) Carrier A Adaptation Carrier Service A Carrier B Adaptation Carrier Service B Carrier C Adaptation Carrier Service C Carrier D Service D Physical Layer Air Link Technology 276 Mobile Communication and Mobile Computing Wireless Session Protocol • supports Client/Server context (shared state), optimization of content transmission • offers semantics and mechanisms, which are based on HTTP • and improvements for use in mobile radio networks with low-performance end-devices 277 Mobile Communication and Mobile Computing WSP overview (1) • HTTP elements: – – – – – extensible request/reply methods extensible request/reply headers uniform contents composed objects asynchronous requests • Improvements: – binary encoding of headers – session headers (Client & Server) – confirmed and unconfirmed network-initiated delivery (Push) 278 Mobile Communication and Mobile Computing WSP overview (2) • Improvements corresponding to HTTP: – – – – negotiations of supported characteristics session suspend/resume multiple complete asynchronous transactions connectionless service • Why doesn’t HTTP suffice? – no compact encoding – insufficient negotiations – Push doesn't exist 279 Mobile Communication and Mobile Computing Characteristics • message size • protocol options – Confirmed Push Facility/ Push Facility (unconfirmed) – Session Resume … • maximum outstanding (unanswered) requests • Header Code Pages (known field names in the protocol headers are separated into pages) • ... 280 Mobile Communication and Mobile Computing Suspend/Resume • • • • Server knows, when a Client accepts data (Push) multi-carrier devices dynamical addressing enables release of carrier resources 281 Mobile Communication and Mobile Computing Wireless Transaction Protocol (WTP) • Goal: – efficient request/reply-based transport mechanism for mobile radio networks and low-performance end-devices • Properties: – – – – – robust data transmission no explicit connection set up and connection release data are transmitted already with the first packet packet oriented abortion-function for outstanding (unanswered) requests 282 Mobile Communication and Mobile Computing Wireless Transaction Protocol (WTP) • Properties: – supports concatenation of messages – further WTP features: • • • • repeated transmission due to packet loss (selective) fragmentation port numbers (UDP) flow control • Transaction = Interaction between Initiator and Responder 283 Mobile Communication and Mobile Computing WTP – transaction classes (1) • Class 0: – – – – non-robust datagram-service for instance for Push during a session shouldn’t substitute WDP the transactions are closed after transmission of Invoke • Class 1: – robust datagram-service – the transactions are closed after transmission of Invoke 284 Mobile Communication and Mobile Computing WTP – transaction classes (2) • Class 2: – robust datagram-service with robust Invoke- and robust Result-messages – the transactions are closed via the Initiator after answer confirmation of the Responder 285 Mobile Communication and Mobile Computing Wireless Datagram Protocol (WDP) • provides connectionless, non-robust datagram-service • is substituted by UDP, if IP the a carrier • re-adaptation to the carrier takes place in the Adaptation Layer • supports port numbers 286 Mobile Communication and Mobile Computing Wireless Transport Layer Security (WTLS) • enables secure connections, uses protocol elements of known, secure Internetprotocols (TLS) • provides mechanisms for encryption, strong authentication, integrity and key management • corresponds to guidelines of national authorities • offers end-to-end security 287 Mobile Communication and Mobile Computing WAP & Security • WTLS (Wireless Transport Layer Security) offers only security via encryption of transmitted data (Grade #1) presently, similar to TLS, only communication trustiness is protected • Grade #2 supports Server- and Client-certificates, for instance via additional chip-cards in mobile phones, so called WIM - Wireless Identification Module 288 Mobile Communication and Mobile Computing WAP & Security UBS (Switzerland) • data with WTLS class 2, 128 bit 3DES encrypted • UBS authentication against mobile phone via certificates with a key size of 1024 bit • participant authentication against UBS via WAP similarly like via Internet with agreement number, password and list-number • automatic connection release (Timeout) embedded – after ten minutes without interaction participant is demanded to reauthenticate with password und list-number input Deutsche Bank (Germany) • WTLS (Wireless Transport Layer Security) • end-to-end-encryption • data encryption already at the mobile phone • decryption at the server Sources: UBC.ch,db24.de 289 Mobile Communication and Mobile Computing WAP-example: access to enterprise data Server WAP-Gateway WML HTTP Web-Server Server Java-Servlet-API LDAP/X.500DirectoryService Dir-X-wap Dir-X-Servlet WMLpages LDAP-Client Profiles LDAP 290 Mobile Communication and Mobile Computing WAP-example: access to enterprise data Example: Siemens Dir-X Meta-Directory Service as a base of a corporate information pool • software-package consists of Directory Server (Dir-X-Metahub) and several Clients, is completely LDAP v3 compatible, based on X.500 • 2 Gateways outwards: Dir-X-Web and Dir-X-wap • secure access also via WAP available, because all security properties of Directory-Servers are handed-on to mobile user • registration via phone number and password, the authorizations/licenses are deposited within the system in user profiles • Java-Servlets built the kernel components of WAP-connection Dir-X-wap-Server: • Servlet-components undertake communication with the Web-Server • LDAP-Client provides data exchange between the Dir-X-wap-Server and the directory service 291 Mobile Communication and Mobile Computing WAP-example: access to enterprise data Dir-X-Wap-Application: • consists of a set of WML-pages containing DSL • Dir-X-Servlet parses DSL-commands • 2 configuration files for an application necessary: – Global Profile: contains information for the Servlet – Application Profile: stores the data that are necessary to execution of WAP-application • In principle, each Web-Server is usable with the product, it must only support the Servlets DSL: Directory Script Language; Language for processing of directory requests from Web- or WML-pages and for representation of obtained results in WML or HTML, contains the language elements for LDAPaccess 292 Mobile Communication and Mobile Computing WAP-examples • Bond/Security-Order processing: Consors, Advance Bank, Deutsche Bank • Mobile “Yellow Pages” – Orange Telecom • Mobile Timetable: wap.hafas.de • Mobile Auctioning: wap.yahoo.de, wap.ebay.de • Mobile „Last Minute Bargain “: – 12snap at Vodafone, presently also with WAP • Mobile marketplaces/stock exchanges (Mobile Brokerage): – http://www.heizoelboerse.de/ – http://www.amazon.de/ 293 Mobile Communication and Mobile Computing WAP-example: Bond/Security-Order Bond/Security-Order •Mobile Banking •Mobile Brokerage 294 Mobile Communication and Mobile Computing WAP-example: Bond/Security-Order Private Banking-> Login page Other services ... Lufthansa, Sixt, etc. 295 Mobile Communication and Mobile Computing WAP-example: Bond/Security-Order Main menu • Brokerage ... Bond/security info 296 Mobile Communication and Mobile Computing WAP-example: Bond/Security-Order Order book • Status of bond transactions • Executed and deleted orders are indicated in the order book for some days more • Partial execution of some order is presented as one open and one executed partial order in the order book • Details to an order could be indicated via dial-up of correspondent Links 297 Mobile Communication and Mobile Computing WAP-example: Bond/Security-Order Portfolio review • Bond/security depots 298 Mobile Communication and Mobile Computing WAP-example: Bond/Security-Order Brief queries • exchange rates of Bonds/Securities with a delay of approx. 15Min • search criteria – Bond/Security-ID and/or – Bond/Security-name 299 Mobile Communication and Mobile Computing 300 WAP-example: soccer/football score source: http://www.wapgoal.com Mobile Communication and Mobile Computing Further WAP-examples soccer/football scores: http://wap.goal.com auctioning: miscellaneous: http://wap.12snap.com http://wap.yahoo.com 301 Mobile Communication and Mobile Computing WAP-example: timetable service Input the address ...wait ... Input -> English -> Query... …wait ... 302 Mobile Communication and Mobile Computing WAP-example: timetable service Input the start & target railway stations ...Dresden, …Hannover ...scroll … Input ..date, time.... …scroll … 303 Mobile Communication and Mobile Computing WAP-example: timetable service After input … search... ..wait.. Selection of train connections with departure platform ...earlier/later... then probably -> END 304 Mobile Communication and Mobile Computing 305 For comparison: PC-timetable service PCtimetable service is still detailed! Details Options Mobile Communication and Mobile Computing WAP-result • • • • • • WML doesn’t bring whole Internet’s diversity to a mobile phone there are no satisfactory rate models at the moment; the data-rates are too low even with GPRS limited input and selection possibilities require a reconsidering of interaction semantics, WAP isn’t oriented for many applications, for instance catalogs with a large selection -> PDAs, appliances, voice input and -recognition with introduction of data services with higher data-rates WAP could lose its relevance possibly -> XHTML however WAP means a first step towards independence from PC by access to Internet contents -> multi-dimensional distribution channels for information WAP means the start for creation of a formidable user population (potentially all mobile radio participants)! 306 Mobile Communication and Mobile Computing WAP-Improvements: WAP2.0 (1) • New version – Internet-based data services on mobile phones – approved by WAP Forum mid-2001 – oriented to GPRS and 3G cellular/UMTS • Useful services at WAP2.0 devices – color graphics and Pictograms – location-specific content, navigational functions and user-friendly menus – animation representations and streaming media – Multimedia Messaging Service (MMS) – large-file downloading (music) – synchronization of user information with personal information manager software on a desktop PC in a remote location Source: http://www.wapforum.org 307 Mobile Communication and Mobile Computing WAP-Improvements: WAP2.0 (2) • WAP 2.0 builds upon the latest Internet standards: – XHTML, TCP/IP, HyperText Transfer Protocol (HTTP/1.1) and Transport Layer Security (TLS) – uses mostly TCP as transport – optimized for small low-performance end-devices • WAP 2.0 supports additionally: – Wireless Telephony Application (WTA), Push, and User Agent Profile (UAPROF) utilize more advanced features in WAP 2.0 than in WAP1.x 308 Mobile Communication and Mobile Computing WAP-Improvements: WAP2.0 (3) • Application development – easier development of WAP applications – More comfortable user environment • Migration aspects – WAP2.0 offers a migration to XHTML (Extensible Hypertext Markup Language) and TCP (Transmission Control Protocol) – Supporting XHTML, WAP 2.0 reduces development costs, allowing developers to write applications for both PC and WAP • Security – offers more secure due to “end-to-end encryption” (from the mobile device to the server) 309 Mobile Communication and Mobile Computing WAP2.0 and i-mode • Competition & Fusion – NTT DoCoMo's I-Mode is a serious competitor of WAP2.0 – NTT DoCoMo's I-Mode moves in the direction of support of XHTML and TCP, too – I-mode and WAP2.0 will probably converge 310 Mobile Communication and Mobile Computing i-Mode An overview Based partially on the materials of NTT-DoCoMo 311 Mobile Communication and Mobile Computing Structure 312 Mobile Communication and Mobile Computing Overview • i-Mode is a product and a trademark of NTTDoCoMo • The enterprise NTT-DoCoMo started in February 1999 with a proprietary development: i-Mode, although NTT-DoCoMo is the member of WAPForum itself • Meantime i-Mode has got a large number of registered users : over 33 millions Source: http://www.nttdocomo.com 313 Mobile Communication and Mobile Computing Properties • i-Mode is packet oriented – always online, no time delays to dial-up – billing regarding data volumes and not regarding to time • simple page markup language – compact HTML (cHTML) • End of 2002: change into XHTML (WAP 2.0) • a great success in Japan, because private computers and private Internet access over fixed networks are infrequent • In Germany E-plus has started i-Mode on 16th march 2002 314 Mobile Communication and Mobile Computing compact HTML • cHTML or compact HTML is a language subset of HTML • very simplified HTML • Lists, Forms, Selections, Input fields are possible • no Frames, no Tables, no CSS • 166 additional pictograms, for instance Fine Heartbreak Motor sports WC 315 Mobile Communication and Mobile Computing compact HTML (2) • • • • • Access key-Attribute for direct link activation respectively for direct selection of input fields pictures can be displayed only in GIF-format, max. 5 KB per page. GIFpictures mustn’t larger than 120*128 dots (little display) also animated GIFs 256 colours (capable of Display) Compact HTML Sites look like “normal” HTML, so also “normal” Browsers like Netscape can work with them i-Mode – on a mobile phone an i-Mode screenshot 316 Mobile Communication and Mobile Computing Network Configuration 317 Mobile Communication and Mobile Computing 318 i-Mode network architecture Connection Network PDC: Personal Digital Cellular Telecommunication System [NSP/Corporate LAN] PDC-P: PDC Packet System M-SCP PGW M-PGW i-mode Server Internet PPM PPM IP IP BS: Base Station IP: Information Provider BS BS BS BS M-PGW: Mobile Message-Packet Gateway Module MS: Mobile Station M-SCP: Mobile-Service Control Point PDC-P Network NSP: Network Service Provider MS MS MS MS PGW: Packet Gateway Module PPM: Packet Processing Module http://www.nttdocomo.co.jp/ Mobile Communication and Mobile Computing i-Mode network architecture (2) • i-Mode Server: - consists of multiple server systems (B-,C-,M-Max ..), each server system is responsible for special tasks - represents the contents of „Information Providers“, operates Internet-Mail and i-Mode-Mail, enables the connection to Internet • M-PGW (Mobile Message-Packet Gateway Module): transforms the protocols: TCP with i-Mode-Server and TLP (Transport Layer Protocol) with PPM • PPM (Packet Processing Module): executes the packet connection with the mobile enddevices/peripherals 319 Mobile Communication and Mobile Computing i-Mode network architecture (3) • M-SCP (Mobile-Service Control Point): authentication of user data (similar to voice communication) • PGW (Packet Gateway Module): transition to other networks, for instance to offer the enterprises a Virtual Private Network (VPN) 320 Mobile Communication and Mobile Computing 321 i-Mode protocol stack AL AL (HTTP) UITP/NWMP TLP CC MM RT HTTP/ UITP/NWMP SMTP TLP RT MM CC PMAP PMAP PMAP TCP/IP TCP/IP LAPDM LAPDM L2 L2 L2 L2 L2 L1 L1 L1 L1 L1 L1 L1 TLP: CC: MM: RT: LAPDM: PMAP: MS PPM Transfer Layer Protocol Call Control Mobility Management Radio Frequency Transmission Management Link Access Protocol on the D-Channel, modified Packet Mobile Application Part M-PGW HTTP: SMTP: UITP: NWMP: TCP/IP: i-Mode Server HyperText Transport Protocol Simple Mail Transport Protocol User Information Transfer Protocol Network Management Protocol Transmission Control Protocol/ Internet Protocol L1: Layer1 (Physical Layer Protocol) L2: Layer2 (Data Link Layer Protocol) Mobile Communication and Mobile Computing i-Mode protocol stack II • UITP (User Information Transfer Protocol): transmits user information such as, for instance, MSN (Mobile Subscriber Number) to i-Mode-Server • NWMP (Network Management Protocol): performs i-Mode Service-functions • TLP (Transfer Layer Protocol): has a simplified transmission procedure and can transmit the signalization and user data together 322 Mobile Communication and Mobile Computing Java for mobile phones • base: Java 2 micro edition and Java MIDP (Mobile Information Device Profile) • downloading of Java-programs (ca. 30-50 kByte); color representation; applications, also games etc. • billing via micro-payment of operator (ca. 1-5 € per application) • products e.g. of Nokia, Ericsson, Siemens; support through big operators 323 Mobile Communication and Mobile Computing M-Commerce - applications • • • • Mobile Shopping Mobile Banking Mobile Brokerage Mobile Traveling 324 Mobile Communication and Mobile Computing 325 Pervasive Computing • Operation as parallel as possible of all users independent of the terminal, it means terminals with different equipment (PC‘s, mobile phones, PDAs, Applicances, etc.) should be supported by most different entrance nets • It means finding a suitable system architecture for “multidimensional“ Internet communication (e.g. regarding end terminals) over *ML (Markup Languages) Mobile Communication and Mobile Computing System architecture, one-dimensional Thin Clients databases, etc. WWW-Browser Web Server Firewall Application Server Firewall 326 Mobile Communication and Mobile Computing 327 System architecture, one-dimensional Internet Inter-ORB Protocol SOAP (Simple Object Access Protocol) proprietary Transactionmonitors protocols BrowserClient HTTP HTMLHTMLHTMLDokumente Dokumente documents Inner Firewall Thin Client Outer Firewall Web-Server Application- proprietary protocols Server proprietary protocols HTMLHTMLCGIDokumente Dokumente scripts business Software Mainframeapplications stateful-connection Stateless-connection data bases Mobile Communication and Mobile Computing Properties of application servers main characteristics: • object-oriented communication systems • component- framework • transaction concepts • security concepts • connection of legacy applications • integration of WWW-services • general support of design, deployment and runtime 328 Mobile Communication and Mobile Computing 329 System architecture, twodimensional Thin Clients Data bases, etc. WWW-Browser Web Server Application Server Firewall Firewall WAP Server WAP-Browser …e.g.: BEA WebLogic M-Commerce Solution Mobile Communication and Mobile Computing System architecture, twodimensional WAP-Server Application Server + WWW Server Backend XSLProzessors convert XML into HTML, WML Servlets call data from the EJBs and generate e.g. XML EJBs standardize access to Backend, create business logic 330 Mobile Communication and Mobile Computing XML (Extensible Markup Language) design principles use in the Internet more powerful than HTML separation of content and style possibility of definition of user-specific document-types ability of XML-document processing 331 Mobile Communication and Mobile Computing XML- document „bibliography“ reference to Style Sheet File special tags 332 Mobile Communication and Mobile Computing Valid and well-formed documents XML-Documents can have a DTD (Document Type Definition). The DTD can be contained in the document or can be referenced by a link. A DTD specifies, which tags are permitted and how these can be combined. It has a special meaning for the processing of documents. The processing programs can check XML- documents for structural errors with the help of DTD. If there is no error then a document is valid! Well-formed documents contain no DTD- reference, but fulfill the XMLsyntax-rules. 333 Mobile Communication and Mobile Computing 334 Accompanying Style Sheet File RULE for root-element Insert of lower elements Cycle Mobile Communication and Mobile Computing Presentation in MS IE 5.0 correspondently IE6.0 335 Mobile Communication and Mobile Computing Other Style Sheet File 336 Mobile Communication and Mobile Computing Other presentation via XSL 337 Mobile Communication and Mobile Computing Change of XML- documents presentation for processing XML XSLProcessor XSL • • • EDI/WML EDI: Electronic Document Interchange Conversion of XML- documents into workable formats (with the help of XSL-Style-Sheets) e.g. into EDI- formats for commercial data processing in the mobile field very interesting for conversion into WML! 338 Mobile Communication and Mobile Computing System architecture, multidimensional Access-Server Application Server + WWW Server Backend XSLProcessors convert XML into *ML Servlets call data from EJBs and generate e.g. XML EJBs Standardize access to Backend, create business logic 339 Mobile Communication and Mobile Computing IBM Websphere Transcoding Publisher • • • • syntax customization of content easy installation little administration effort changeable, expandable architecture of components 340 Mobile Communication and Mobile Computing IBM Websphere Transcoding Publisher & WAP – capable mobile phone Evaluation of used profiles 1.Request over port xx Text Clipper: transforms HTML into WML 7.Output of contents Fragmentation Transcoder: Change into WML-decks 341 Mobile Communication and Mobile Computing Oracle Application Server Wireless Edition • • • syntactic customization of content renewable, expandable architecture of components good customization of specific content Request Manager authentifies user and calls Master Service Request Manager Client Request Master Service configures und starts an adapter Master Service Transformer A transformer converts information in suitable Clientformat the adapter fetches the Information (via e.g. HTTP, SQL, etc.) Adapter 342 Mobile Communication and Mobile Computing Oracle Application Server Wireless Edition Expiry of a user request 343 Mobile Communication and Mobile Computing Oracle Application Server Wireless Edition Adapter and Transformer 344 Mobile Communication and Mobile Computing Contents customization with XML / XSLT • Separation of content and presentation • content client- independent in XML • XSLT: XSL transformations: a XML- data format is changed into a new data format (not necessarily XML), this new data format can include platform dependent information about the presentation of data besides the main information • presentation client- dependent in some XSLTs • XML-Support in many data bases • the server itself needs additional logic 345 Mobile Communication and Mobile Computing Contents customization with XML / XSLT server-sided requests: • reconnaissance and classification of the client • choice of the suitable style sheets • parameter handover to XSLT • Processing of other documents (e.g. bitmaps) 346 Mobile Communication and Mobile Computing Example application: Pizza ordering service • content and logic in same XML-document • no presentation-semantic in XML, so all client- abilities can be used in XSLT • but stylesheets are not reusable 347 Mobile Communication and Mobile Computing 348 Example application: pizza ordering service <?xml version='1.0' encoding="ISO-8859-1" standalone="no" ?> <?xml-stylesheet type="text/xsl" href="Pizzaservices.xsl"?> <?xml-stylesheet type="text/xsl" href="Pizzaservices.lynx.xsl" media="lynx"?> <?xml-stylesheet type="text/xsl" href="Pizzaservices.lynx.xsl" media="palm"?> <?xml-stylesheet type="text/xsl" href="Pizzaservices.wap.xsl" media="wap"?> <?cocoon-process type="xsp"?> <?cocoon-process type="xslt"?> <xsp:page language="java" xmlns:xsp="http://www.apache.org/1999/XSP/Core"> <xsp:logic> class Item extends Vector { private int[] numbers; public Item () { super (); numbers= new int[10]; } public void setNumber (int nr, int a) { numbers[nr]=a; } public int getNumber (int nr) { return numbers[nr]; } } ... Mobile Communication and Mobile Computing 349 Example application: pizza ordering service <services> <service> <name>Hi Pizza</name> <banner>hellopizza.jpg</banner> <description>Hot Ware on Order</description> <location zipcode ="01277"> <address>Bodenbacher Strasse 16b, 01277 Dresden</address> <phone>03512540707</phone> <fax>03512540708</fax> </location > <location zipcode="01127"> <address>Mohnstraße 50, 01127 Dresden</address> <phone>03518485590</phone> <fax>03518485558</fax> </location > <proposal> <category name="Pizza"> <food> <name>Pizza Kentucky</name> <description>Salami</description> <price size="Normal">8.00</price> <price size="Jumbo">15.00</price> <price size="Pan">10.00</price> </food> ... Mobile Communication and Mobile Computing Pizza ordering service: PC-presentation 350 Mobile Communication and Mobile Computing Pizza ordering service: presentation on Palmscape and in WAP 351 Mobile Communication and Mobile Computing XHTML 352 Mobile Communication and Mobile Computing XHTML • XHTML™ 1.0 is Extensible HyperText Markup Language (Second Edition) – reformulation of HTML 4 in XML 1.0 – use instead of WML2.0 correspondently cHTML (iMode) – basis for integration between WAP2.0 and i-Mode WWW: http://www.w3.org/TR/xhtml1/#xhtml 353 Mobile Communication and Mobile Computing XHTML • supporting via as well as WAP-Browsers also Netscape Navigator and Internet Explorer • constituents: – DTD (Document Definition) – XSL (Extensible Stylesheet Language) • large quantity of supported tags in comparison with WML2.0 and cHTML – – – – – CSS frames tables forms/input fields applet calls 354 Mobile Communication and Mobile Computing XHTML vs HTML • XHTML describes data <-> HTML displays data! • XHTML – combining HTML and XML, and their strengths • XHTML is oriented to internet/PC and mobile internet/ mobile phones and hand helds • XHTML - compatibility – everything has to be marked up correctly -> "wellformed" documents – pages can be read by all XML enabled devices – upgrading of XML supported browsers – compatibility to all browsers – backward browser compatible 355 Mobile Communication and Mobile Computing Mobile agents 356 Mobile Communication and Mobile Computing 357 The agent- model • an agent-system consists of the agents themselves and an execution engine for working with agents. The execution engine offers basic services to the agents • Agent is an independent program generally, it consists of data, code and execution state, it works in interest and order of a third party (e.g. user, application). Mobile Communication and Mobile Computing Agent system 358 Mobile Communication and Mobile Computing Agent model Client Client create Agent simple Serverinterface migration code, data, state result Agent code, data, state simple Serverinterface • migration: transfer of code, data, state • local interactions with server • transfer of the result 359 Mobile Communication and Mobile Computing 360 Properties of mobile agents Advantages: + reduction of network load + autonomy and asynchronity + dynamic adapting in environment + heterogeneity + robustness and error tolerance + scalability + personalization and individualization + dynamic code-installation + encapsulation of protocols Disadvantages: – need of special execution engine (Middleware) – high security requirements – transfer of code, data, state – Decision: migration vs. remote communication Mobile Communication and Mobile Computing Applications • • • • • • • • • E-commerce database requests intelligent e-mails Office applications/workflow traffic telematic Web surfing load balancing virtual enterprise Mobile computing 361 Mobile Communication and Mobile Computing Existing agent systems • • • • • Voyager (ObjectSpace) Aglets (IBM) Concordia (Mitsubishi Electric) Grasshopper (IKV++) Odyssey (General Magic) • • • • Mole (Stuttgart), Ara (Kaiserslautern) Agent TCL (Dartmouth University) MASIF (OMG) Telescript 362 Mobile Communication and Mobile Computing Middleware for spontaneous Networking 363 Mobile Communication and Mobile Computing Vision • spontaneous networking of electrical devices (but not only computers) • very simple connection JINI • platform independence UPnP 364 Mobile Communication and Mobile Computing JAVA Intelligent Infrastructure, JINI • „Middleware“ for spontaneous networking; originally developed from Sun • JINI Connection Technology enables dynamic control of networked services and devices • Partitioning into so called Lookup Groups: different sets of lookup-services • basic operations: – Discovery: offers locating of a directory services (lookup service) – Join: enables acquaintance/ registration of the services implemented from some device 365 Mobile Communication and Mobile Computing JAVA Intelligent Infrastructure, JINI • Lookup-Service enables locating of services via other users/devices per lookup-operations • Leasing offers time-limited allocation of resources (using of services) • Jini integrates distributed events processing and distributed transactions further on for coordination between services 366 Mobile Communication and Mobile Computing General procedure: step 1 Lookup service Discovery & join protocol JINI device / service Discovery lookup Client 367 Mobile Communication and Mobile Computing General procedure: step 2 Lookup Service Proxy upload JINI device / service Proxy download Client 368 Mobile Communication and Mobile Computing General procedure: step 3 Direct Connection JINI device / service Client • synchronization • data exchange between Device and Client over own communication protocol 369 Mobile Communication and Mobile Computing JINI - Details • Proxy hides all details of communication and is executed in the form of Client (dynamic installation of Stubs) • security over RMI - Security Extension Framework • new versions of JINI Starter Kits include advanced possibilities, for instance: – – – – Caching of request results by Clients unicast-discovery comfortable control of using period (lease) asynchronous receiving of events among other features • further development via JINI Community: – for instance JINI Surrogate Architecture: supports devices that do not have all required resources for JAVA and JINI – printer working group 370 Mobile Communication and Mobile Computing JINI - Assessment • suitable to support scenarios from the field of Ubiquitous/Pervasive Computing • JINI is a part of JAVA 2 Micro Edition 371 Mobile Communication and Mobile Computing Universal Plug and Play, UPnP • reply of Microsoft to JINI • Embedded in UPnP- forum • with this improvement corresponding to Plug- and- Play Standards, the PC peripheral devices should be connected to a home-network problem-less • via Universal Plug and Play diverse devices can communicate with each other like with Jini 372 Mobile Communication and Mobile Computing Universal Plug and Play, UPnP • essentially based on open standards like TCP/IP and therefore is compatible to each network • in Windows ME integrated • a special toolkit for creation of drivers on the basis of UPnP developed by INTEL 373 Mobile Communication and Mobile Computing 374 UPnP architecture Common Abstractions Home application Universal PnP Common Interfaces Discovery Media Independence Description Usage Bus attached Internet Protocol attached IrDA X10 .. IR PLC .. (ISA,PCI,USB, Network media (Ethernet,HomeRF, HomePNA,.. IEEE,1394,IR,..) Mobile Communication and Mobile Computing Further approaches HAVi – Home Audio and Video Interop. • essentially supported by the vendors of consumer-electronics field • UPnP Forum is interlocked however represented more broadly on the market (specially also in computer-industry) HomePlug • consortium for standardizing of data communication over (low voltage) power cable • performance like by IEEE 802.11b • the members are among others Cisco and Panasonic 375 Mobile Communication and Mobile Computing Services and system support for Mobile Computing 376 Mobile Communication and Mobile Computing Mobile Computing: system support Essential properties und requirements: • dynamics, localization • heterogeneity of networks and enddevices • security problems 377 Mobile Communication and Mobile Computing Mobile distributed applications: example Local Resources, Error Protocols Product Data Main office Caching Maintenance technician Client LAN-Access Mobile Access - very different performance and charges: GSM, ISDN, LAN Software-technical, automatic adaptation to concrete system environment Example: Access to picture data/compressed picture data/graphics/text 378 Mobile Communication and Mobile Computing Problems and requirements Problem fields: • dynamic system and net configuration • dynamic change of Quality-of-Service-properties • uncoupling/re-connection • transparency of resource access • security aspects Requirements: • connection monitoring and selection • treatment of uncoupling/off-sets and migration; emulation of services • configuration update • localization of mobile servers and clients • advanced security and transaction services 379 Mobile Communication and Mobile Computing Mobile RPC Goals: • Mobile Binding – Transparent call to an alternative server by non-accessibility • Datagram RPC – Queuing of calls in disconnected status • Queued RPC – intermediate storage and delivery of results after re-coupling Realization: • Attachment on existent RPC- systems (without new implementation or internal code changes) 380 Mobile Communication and Mobile Computing Time Behavior Datagram RPC •Client •Server •DCE RPC •Datagram RPC T1 T2 Time T3 T4 Decoupling Net connection RPC reaches Server Return to Client 381 Mobile Communication and Mobile Computing Message Queuing: MQ Series example • Base: Messages, Queues with Queue Manager • dynamic coupling between applications and local Queues via logon/logoff • using of Queues for transmission or receiving; also mixed using is possible • coupling of distributed Queue Managers via Message Channels • Internet Gateway, C++- and Java-Support • support of essential operating system platforms 382 Mobile Communication and Mobile Computing Example scenario Computer A Computer B Queue Manager AppQueue lication Manager 1 MQPUT Queue Manager Message Channel Queue Manager Application 2 MQGET • decoupling of application through Queue Manager: – Message forwarding is possible even if application isn’t running 383 Mobile Communication and Mobile Computing N:M - communication Access to Server via multiple Clients • Load balancing (selective delivery) or • Parallel processing (replicated delivery) C A D B Queue, with optional support of message priorities E 384 Mobile Communication and Mobile Computing 385 Message Queuing: Assessment Advantages + simple manageability + robust message delivery + flexible application fields (for instance load balancing, parallelization, batch-transmission of branch data etc.) + relevant for easy coupling of programs, for instance via Internet, or for Mobile Computing Disadvantages − limited communication semantics − interaction model is different than with procedures/method invocations − limited accessibility of higher services − only several proprietary decisions up to now, only step-by-step standardization Mobile Communication and Mobile Computing Application Structure Ethernet Distributed Database Ethernet DB E-Fax-Order Branch office Firm xDSL Application GSM Ethernet Cache Resource Mobile Station Communication path Management DB-Access Distributed Database Client X 386 Mobile Communication and Mobile Computing Domain-concept 387 Mobile Communication and Mobile Computing Main functionality: Domain and Station Manager Domain Manager: • management of all global objects (users, global available resources, stations, net topology) Station Manager: • management of all local objects of a station (net access, running applications etc.) 388 Mobile Communication and Mobile Computing Architecture of Station Manager Application Subsystem (Application Programming Interface) Subsyste m (System Calls) Location Service Registry Service Resource Broker Application Data Mobilizer and Manager Bandwidth and Cost Authentication and Encryption Service Management Service Active Database Disconnected Operation Handling Service (CS, QS, CHS, BMC) 389 Mobile Communication and Mobile Computing Mobile Multimedia Email: message transfer User Agent email protocol Subsystem email protocol Queuing Service Queuing Service email protocol Email Proxy Message Store message transfer Mobile Enhanced Message Handling System 390 Mobile Communication and Mobile Computing Mobile Multimedia Email: selection of quality parameters Cent Cent 391 Mobile Communication and Mobile Computing Mobile File Manager: example CODA • distributed file system, which offers the unbreakable access to data also in the case of server shut-down or net failure • developed at the Carnegie Mellon University • based on AFS (Andrew File System, distributed file system in UNIX-environment) • relatively transparent to the applications 392 Mobile Communication and Mobile Computing CODA overview • based on the model of „Disconnected Operations” • client keeps Read- and Write-access on the data via inset of a local buffer (Cache) also during temporary disconnection from net • with re-connection system forwards changes and recognizes potential conflicts • for different operating systems available (for instance LINUX, Solaris, Windows) 393 Mobile Communication and Mobile Computing 394 CODA system model Replicated Server: High availability Net communication at file open and close Disconnected Client: local data access on Cache Client (“Whole-File-Caching”) Mobile Communication and Mobile Computing 395 properties of consistence (Coda) • Callback – logic reference from server to the active client, used for immediate information about file changes via other client • after connection failures the file in client cache remains valid till to timeout termination (as a rule several minutes) • thereby reduced consistency • conflict processing explicitly in interactive form, however low conflict probability Mobile Communication and Mobile Computing Conflict processing (CODA) • extensive automation as objective purpose, however isn’t possibly for: – Update/Update-conflict: independent double update of the same file – Delete/Update-conflict: independent erasure respectively update of the same file – Name/Name-conflict: generating of two files with the same name Manual access after user notification 396 Mobile Communication and Mobile Computing Cache management (Coda) • “Cache-Misses”: searched file isn’t in the ClientCache – processing failure in the disconnected status • priority list of important files per user – the highest priority is always kept in the cache (for instance by system programs, user profiles, address files etc.) – other priorities: exchange strategies correspondent to importance – dynamic generated files via list of essential operations referenced (for instance actual test protocol etc.) 397 Mobile Communication and Mobile Computing 398 File synchronization under Windows - Windows: over System Control -> Management -> Services so called „file replication (server)“ for synchronization of data between different servers - under Explorer -> Extras -> Synchronization: - Synchronization of own Homepage with PC - Synchronization of Sites in WWW Mobile Communication and Mobile Computing E-Hand - connects existing Enterprise Systems with mobile end-devices - platform independent - very simple synchronization and data transfer - supports XML, ODBC and SyncML Advantages: - contains Web-similar user interface for application installation and for mobile participants http://www.ehand.com/ehand/ 399 Mobile Communication and Mobile Computing E- Hand 400 Mobile Communication and Mobile Computing Mobile databases support Motivation: • SFA-Sales-force-automation: -> actual information about clients, competitors and market trends to the field (outside-) workers • emergent business transactions on the site -> efficiency increasing Example: Pharmaceutical Industry • visit of 6 up to 8 distribution medics per day • to bring dialogue to the point more quickly – previous information about the medic (contacts, receipt prescription habits) are recallable from the firm-net • • presently still manually due to dialogue recording and product documentation in the future via mobile databases permanently faster access to data without inconvenient storage, connection establishment etc. 401 Mobile Communication and Mobile Computing 402 Mobile databases support • mobile databases offer principally data synchronization and replication of enterprise servers and for mobile end-devices like PALM etc. • due to increasingly mobile business processes there is a necessity of databases, which must perform these functionalities among other things: – quickly – compatible to as many as possible mobile systems • 2 mobile database types: – “asynchronous synchronization”: for instance SQL Remote of Sybase • data replication between central database and multiple remote databases • also offline-working is possible due to email-queuing principle (sent, if connected) – “synchronous synchronization”: for instance Sybase Mobilink Synchronization Server • co-operation with databases of other vendors (via Server Middleware) • permanent connection necessary, for instance via GSM Mobile Communication and Mobile Computing IBM DB2 Everyplace • compatible for instance to Windows CE, PalmOS, EPOC ... • footprint: ~150 k (storage requirements) • for data balancing DB Everyplace Sync Server is necessary – synchronization with other Handhelds without PC! • includes so called Mobile Devices Administration Center enables central management of all mobile end-devices of a enterprise • supports integration of enterprise data from different databases and other sources (DB2 replication technology, JDBC, Adapter API for customized decisions) • data are encrypted during synchronization (56 or 128 Bit) • supports automatic conflict processing 403 Mobile Communication and Mobile Computing IBM DB2 Everyplace Mobile Devices Source: http.//www.ibm.com Synchronization Server Backend IBM DB2 Microsoft Oracle Informix Sybase Other DBMS (JDBC) 404 Mobile Communication and Mobile Computing Oracle Lite • 3 constituents: – Oracle Lite DBMS • database with low footprint (storage requirements) • Java-enabled – iConnect • components for synchronization and creation of messagingapplications (principle of message queues) – Web-to-go • components supporting development, deployment and management of mobile Web-applications 405 Mobile Communication and Mobile Computing Oracle Lite replication via Internet File-based replication 406 Mobile Communication and Mobile Computing Sybase SQL Anywhere Studio • • • • • • • • mini-database, can be operated on the PDAs supports PalmOS, EPOC and WindowsCE small „footprint“: ~50kByte developer can adapt the database according to the required SQLproperties, modular design principle synchronization enables data balancing with the enterprises database, all well-known database vendors are supported only the changed data are transmitted both local (for instance B. Hotsync (Palm)) and remote synchronization supported architecture similar to IBM DB2 Mobile Connect (Source: http://www.sybase.com/products/anywhere/) 407 Mobile Communication and Mobile Computing Further approaches • Microsoft Mobile Information Server • Lotus Everyplace • numerous further products, mostly similar architecture concepts 408 Mobile Communication and Mobile Computing Further sample applications • Traffic management • Mobile Information Services • M-Commerce • • • • • Service technician Customer consultant Field workers in general Environmental engineering (measurement data logging) Medic (visits on site) 409 Mobile Communication and Mobile Computing Traffic management Berlin “Global” Provider Paris Dresden Service Center “Local” Provider Services: • Traffic engineering • Travel information • Maintenance service • Mobile Office 410 Mobile Communication and Mobile Computing Traffic management Internet Information Provider Info GPS Info Info GSM 411 Info Info Info Center B Center A Virtual Private Network PSTN/ ISDN Distributed Information services End-user Distributed Service-Center Mobile Communication and Mobile Computing 412 Application scenario: car maintenance Host Printer Notepad HUB PC Terminal Mobile Communication and Mobile Computing 413 Online-information services Client low band width Server for instance WWW Client (mobile) low battery resource • Client/Server-access by individual requests • additionally: separate broadcast-channel from Server to the mobile Clients: transmission and caching of frequently requested information; thereby lower battery consumption (receiving less expensive as sending for the Client) Mobile Communication and Mobile Computing Optimization: basic concept • information in Publication-Group: regular Broadcast • information in On-Demand-Group: Client/Serverqueries • exchange between both groups on the basis of: – – – – access frequency (for instance on WWW-pages) page modification frequency channel bandwidths clients storage volumes (Cache) 414 Mobile Communication and Mobile Computing Mobile e-Mail • Eudora Internet Suite, consists of: – Eudora email for the Palm computing platform – EudoraWeb browser for the Palm Computing platform – Eudora Mail Conduit • Properties: – Eudora and EudoraWeb browser support SSL (Secure Sockets Layer) and TLS (Transport Layer Security), i.e. end-to-end security – synchronization of bookmarks between PC Web-Browser and EudoraWeb browser via Eudora Web Conduit – synchronization with PC-Email applications – several Email-accounts Quelle: http://www.eudora.com 415 Mobile Communication and Mobile Computing Alternative M-Commerce applications • 12snap.de (pronounciation: “one two snap”) – Auctioning channel • www.paybox.de – Cashless payments 416 Mobile Communication and Mobile Computing 417 Sample: 12snap system architecture Offers via Cellular Broadcast mobile radio net D2 external provider center Internet Automatic processing of the orders which are incoming via phone-service; also coupling of WAP and telephony Call Center Users are registered by 12snap and enable direct debit, respectively booking via the credit card; Orders are sent to a Call-Center via keyboard tone, client identification takes place via his phone number (CLIP = Calling Line Identification Presentation) Mobile Communication and Mobile Computing Sample: paybox.net • Client is registered in the Internet by paybox.net and enables direct debit • Client obtains as a result so called Paybox-PINs; using Paybox-PIN client can unblock the transactions • purchase payments in the Internet are carried out as follows: – Client selects „Paybox“ as a payment type – Merchant sends transaction to Paybox-provider via secure data connection – Provider dials up the clients via phone numbers stored in his master data – then Client can unblock the transaction with his PIN – Paybox transfers money via direct debit and forwards it to the Merchant 418