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Wireless Networks Amit Jain and Petter Karal Media Tech Club Sloan School of Management May 2, 2000 1 Mobile + Internet = 2 The Mobile Internet mCommerce 3 The Mobile Internet work anywhere 4 The Mobile Internet play anywhere 5 The Mobile Internet anytime 6 MediaTech Wireless 101 Technical workshop How wireless works Today’s different systems The future of wireless technology Today Business workshop Markets and players Trends Success factors May 9 7 Technology enables marketing Wireless technologies are very fancy, fun and intellectually exciting Don’t fall into the tech trap The business workshop is the “really” important part - this is preparation 8 Agenda How does it work? Today’s systems Wireless technologies in the near future 9 A wireless network 10 Connects a mobile phone... Mobiles send and receive radio signals to base stations (called BTS) Each BTS has a service area Several BTS are connected to a BSC over copper, fiber or microwave links When a mobile moves from one service area to another, a handoff occurs BSC directs the handoff, with or without the assistance of the mobile 11 To the rest of the world! BSCs are connected to Mobile Switching Center (MSC) MSC connects mobile to other phones/devices in the world MSC maintains subscriber database for Billing Roaming agreements Paging mobiles for incoming calls 12 Talking over the air Bandwidth is limited (and expensive) FCC raised over $5 billion in PCS auction UK licenses recently auctioned for $35 billion Each operator has 5-10 MHz Each mobile call needs ~25KHz Frequency must be re-used Wireless link unreliable Severe radio propagation losses Interference from other networks and users 13 Air interface standards Examples: FDMA, TDMA, CDMA Define how the phone talks to the network Determine how network solves the frequency reuse, reliability, and voice quality problems Determine cost of a network and its capacity Most phones are designed for one air interface and one frequency Multi-mode phones work over multiple air interfaces but cost substantially more 14 *DMA compared ! Consider a room with many people trying to have a conversation. If they all speak at different frequencies, FDMA If they take turns to speak, TDMA If they all speak together but in different language, CDMA. 15 Frequency Division Multiple Access (FDMA) 1 2 …. Spectrum Spectrum is divided into channels Each call takes one channel for the entire duration of a call Geographical separation allows channels to be reused Still used in US analog systems 7 2 3 7 1 4 4 6 5 2 3 7 1 4 16 Time Division Multiple Access (TDMA) Channels are divided into time slots Each user gets a channel and a time slot Uses digital modulation to improve voice quality and capacity GSM is the leading TDMA based standard 17 Code Division Multiple Access (CDMA) All users use the same wide band channel Users are separated by encryption or codes Encryption/decryption needs huge computational power Provides dramatically higher capacity Well suited for transmitting packets i.e. data Used by military since 50s, commercialized by Qualcomm in 90s 18 Agenda How does it work? Today’s systems Wireless technologies in the near future 19 End-to-end mobile phone standards Each standard covers air interface, mobility management, switching, inter-connectivity and other issues AMPS : Advanced Mobile Phone System Established 1983 by AT&T GSM : Global System for Mobile communications Established 1990, Europe Ericsson, Nokia, Omnipoint, Pacific Bell, all European carriers cdmaOne Established 1995 Qualcomm, Motorola, Lucent, Sprint PCS Others (D-AMPS, TDMA, N-TDMA, TACS, DECT...) 20 AMPS Still used in AT&T and AirTouch Networks in the cellular band FDMA based air interface Poor voice quality Handoffs are done without the assistance of the mobile, unreliable 21 Higher capacity (2X over AMPS) TDMA air interface instead of FDMA Better voice quality Digital voice encoding/decoding Excellent roaming One phone, many networks SIM cards Painless phone upgrades 22 Higher capacity (5X over GSM) CDMA air interface instead of FDMA Superior voice quality Digital encoding/decoding Smooth handoffs Simpler network design 23 GSM is predominant TDMA PDC CDMA 8% 11% Total worldwide subscribers: 490 million 13% 67% GSM Share of digital mobile subscriber market 24 Agenda How does it work? Today’s systems Wireless technologies in the near future 25 The Mobile Internet vision Any application... …on any device …anytime …anywhere “The Network is the Computer” - Scott McNeally 26 The third generation of wireless (3G) is coming Value to user 3G: High-speed multimedia internet access 2G: Digital voice+ 1G: Analog voice ~1980 1990 2002 Introduction 27 3G adds functionality and more connectivity Multimedia capable Pictures Music Video Internet connected Packet-switched (144 to >2000kps) Location sensitive 28 Access by many different devices and technologies Access from different devices (“terminals”) at different times Phone device Car PDA/palmtop computer Desktop Fridge? 29 Today’s phones evolve into funky devices 30 3G must overcome several challenges Standardization Tug-of-War over technical aspects of global standards waged in many forums Migration Old customers, networks and frequencies can’t simply be discarded Technology High-speed data devours batteries, heats handsets and uses a lot of spectrum 31 Standardization for 3G Three coinciding technologies DS-CDMA (UTRA FDD) MC-CDMA UTRA TDD “Harmonization” - maximizing compatibility Doesn’t matter all that much Most consumers aren’t global Multi-band/multi-mode phones can roam the world anyway 32 Several step-stones for 3G migration Circuit-switched internet access WAP (discussed later) Upgrades to 2G (“2.5G”) GPRS: Upgrades GSM to PS at 50-115kps cdma2000: High-speed data over cdmaONE Upgrades to 3G of current networks EDGE: Upgrades GSM/GPRS and TDMA/AMPS to 3G, with data rates of 50473kps 33 Related technologies Operating systems (OS) for terminals Short-distance wireless networking Applications and services Security systems Location specificity New input/output technologies 34 Operating systems Battle to become the “Windows of Wireless” Players come in at different angles EPOC (Symbian) - the OS for the PSION PDA Palm OS Pocket CE - was: Windows CE, Microsoft’s “all gadgets” OS Phone.com - WAP browser “all you need”? Mobile Linux - no position now, but potential Java - might make underlying OS “irrelevant”35 Short-distance wireless networking: Widely adopted standard Cheap chip that communicates via microwave radio Enables devices within 30’ to network spontaneously (forming “Piconets”) Speed: 1mps, allegedly bound for 10mps 36 Many kinds of applications “Hardcoded” functionality Installed software (possible today on PDAs, Palmtops; not on cell phones) Wireless-enabled web sites Network applications - run them on distant servers using browser 37 Example applications E-mail = instant messaging Arrival services Device knows you and your position - offers relevant booking services for transportation, as well as for dining and entertainment Web-based enterprise systems Store and retrieve files, look up information and perform transactions from anywhere, anytime 38 Security systems enable transactions Main focus: To enable secure transactions Key technology: Public Key Encryption (PKI) Many players race to define industry standard Strong contender: Hardware-based systems (smart-cards; chips) 39 Your service will be tailored by your location Location tracking required by US law for 9-1-1 purposes (“e911”) Several technologies Analysis of signals and handoffs GPS (not used in mobile devices yet) Bluetooth (not sufficient for e911, though) Current systems are not very precise; will improve 40 New ways to operate your wireless device New input technologies Palm Grafitti (has been around for a while) Keyboard variants Integrated camera Speech recognition New output technologies New screens Screen specs - glasses with display Crazy stuff coming: Direct retinal projection, implants, AI, neural interfaces 41 And the killer app is... Voice! 42 Wireless Application Protocol, W@P Emerging standard for presentation and delivery of data on wireless phones Designed to work within the constraints of existing wireless and phone technology Standard initiated by Unwired Planet, now Phone.com, with the support of Nokia, Ericsson and Motorola. Today WAP Forum has 100+ members 43 W@P architecture Phone WAP Gateway MicroBrowser - WML - WMLScript - WTAI - Web Server WML Decks Encode Reqs Decode Reqs DNS Proxy Server Optimization WAP Protocols WSP/WTP/WDP HTTP Server Content CGI Java/ASP Standard HTTP 1.1 44 Why do we need W@P ? Wireless devices are not PCs Devices are small Limited CPU, RAM Support Voice, Telephony Wireless channel is not copper or fiber Unreliable Low Bandwidth High Latency Standardization is essential for developing applications 45 W@P protocols Micro-browser, WML, WMLScript, WTAI Security Independent of wireless standards 46 WML: Decks and cards 1> Pizza 2> Chinese 3> Indian - Web servers always 1> Pepperoni 2> Meat Lovers 3> Veggie Cost: $11 Buy? 1> Kung Pao 2> Schezuan 3> Fried Rice Cost: $8 Buy? 1> Tandoori 2> Naan Bread 3> Dosa Cost $9 Buy? One “deck” send “decks” - Decks contain “cards” - Each card is ONE user interaction - Decks maintain state information One “card” 47 WAP Gateway Translates WAP requests to HTTP and TCP/IP Encodes and decodes content to reduce size and number of over-the-air packets Off-loads phone from computation intensive tasks Maintains cookies / user information Caches commonly accessed information 48 Cellular Digital Packet Data (CDPD) Technology currently used by Palm, RIMM Palm.net, GoAmerica (NASDAQ:GOAM) resells service from ATT, Bell Atlantic, Ameritech Uses a digital overlay of existing network Data sent using TCP/IP Maximum data rate = 19.2 kbps Billed by the byte 49 CDPD and WAP compared CDPD Network Overlay Required Uses TCP/IP Dedicated devices like Palm, wireless modem Packed-switched Charge by the byte W@P Works on existing network Own network protocol Software upgrade of phone Circuit and Packet Charge by the minute 50 i-mode Wireless service launched in spring 1999 in Japan by NTT DoCoMo “3G light” Web content based on subset of HTML Packet-switched, multimedia enabled Low bandwidth (9.6kps), but improved by compression and will move to 14.2kps Extremely successful: 6 .1M customers; growing at 200,000/week Thousands of services provided 51 Q&A 52 Conclusion The main 2G standards are GSM and CDMA 3G standards are coming that will enable consumer multimedia internet from any device Many new dimensions to internet services (context-specific, on-the-spot, continuous) Technological feasibility drives the evolution of the Mobile Internet (for now) Be skeptical to hype 53 Resources 3G acronym expander: www.nokia.com/3g/acronyms/0,7076,,00.html Mobile commerce glossary: maffin.net/mobilecommerce/glossary.htm Great news compilation on wireless: www.mobic.com Ericsson background papers (pretty technical, but great): www.ericsson.se/review/issues.taf Bluetooth homepage: www.bluetooth.com WAP Forum: www.wapforum.org Equipment providers’ homepages: www.motorola.com www.ericsson.com www.nokia.com Web site on wireless devices: www.allnetdevices.com Consultancy gives “teasers” on its reports: www.ovum.com 54