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University of Turkish Aeronautical Association Computer Engineering Department CENG 453 Mobile Computing Tansel Dökeroglu, Ph.D. [email protected] Room 169 1 Books 2 Books 3 Mobile Computing • Mobile computing refers to computing in a distributed system in which some processes or processors can move. – Moving processes logical mobility, realized by agents. – Moving processors physical mobility, realized by moving devices. • Mobile computing extends a distributed computing environment with a new dimension of mobility. – Most existing mobile computing systems are based on clientserver computing systems. – Recent mobile computing solutions consider general distributed computing, namely, peer-to-peer computing environments. – Mobility generalizes the network reconfiguration problem. • Many mobile computing techniques have their root in distributed systems. 4 Mobile Computing vs. Others • Mobile computing relies on wireless networking and communications and extends distributed computing – new issues of client movement, location management and context-awareness, not to mention the limitations of devices. • Pervasive computing extends mobile computing, making use of small equipment and sensors. – The number of devices and volume of data can increase several orders of magnitude – new issues like data streaming need to be handled. 5 Mobile Computing vs. Others • Networking is the base layer, with communication primitives. • Wireless networking and communications extends networking protocols to cover lack of link and movement of devices – GPRS, 3G (WCDMA), IPv6, WLAN. • Distributed computing covers fundamental issues to utilize computers over a network. – coordination mechanism to make the solutions work – general problem solving approaches • Internet computing is more on the practical issues of developing programs and applications that work over internet. – using Java and related technology. – can be considered a case of distributed computing. 6 Mobile Computing is • Taking a computer and all necessary files and software out into the field. • Being able to use a computing device even when being mobile and therefore changing location. Portability is one aspect of mobile computing. • The ability to use computing capability without a predefined location and/or connection to a network to publish and/or subscribe to information. • A variety of wireless devices that has the mobility to allow people to connect to the internet, providing wireless transmission to access data and information from wherever location they may be. 7 The Era of “Mobile Computing” Mobile Computing Mobile/Wireless Network 8 GSM Base Stations Ericsson RBS 2000 Nokia PrimeSite 1997 Motorola Marco Specs • 1995 • • • • • • • • • • • 1995 • Newton OS 1.3 4MB ROM 687KB Flash RAM 320x240 Monochrome LCD resistive touchscreen RS422 serial port Localtalk support 1 PCMCIA Slot (5V or 12V) 1 Sharp ASK infrared port 4 AA batteries, rechargeable NiCd batteries may be used First released January 1995 It weighs 1.8 pounds and is 7.5 inches high, 5.8 inches wide and 1.4 inches deep Street price: USD 900-1400 10 The Nokia 9000 Communicator 1996 11 Laptops, Notebook, Sub Notebooks & Netbooks Laptops: 1991 Notebooks: 1996 Netbooks: 2006 12 Wearable Computers 13 Wireless Helmet? 14 The Projection Keyboard 15 Today Andriod The iphone MyVu The iPad Plastic Logic QUE 22Moo Portable projectors 16 Re-Inventing the Tablet: 2010-2011 2010 Microsoft: Soon 17 Properties of a typical smart phone 18 Properties of a typical smart phone 19 Mobile Computing Architecture 20 Mobile Computing • Motivations – Availability of wireless network at reducing communication cost. – Widespread use of handheld devices with increasing computing power and lower cost. – Integration of communication and computing devices (Tablet computer, SmartPhones). – Detection of the physical or logical location of a device. – Making use of wireless network to access information and perform data processing, resource sharing at high capacity servers. – Extend the ability and usefulness of handheld devices. • Goal – Access to information anywhere, anytime, anyway. 21 Mobile Computing vs. Others • Related concepts – Wireless computing • computing without a wire. • the most primitive form, e.g. using 802.11b, 802.11g or bluetooth. – Nomadic computing • computing on the move. • clients or users are moving. • physically mobile computing, perhaps prolonged disconnection. – Ubiquitous computing • invisible computing or subconscious computing. • computers and their functionality available to users without being noticed. – Pervasive computing • immersive computing (virtual reality). • use of wearable computers. • a current name for ubiquitous computing. 22 Mobile Computing vs. Others • built upon distributed computing discipline • closely related to – networking and wireless communications, – internet computing and cloud computing, – pervasive computing. 23 Pervasive computing also called ubiquitous computing is the growing trend towards embedding microprocessors in everyday objects so they can communicate information. The words pervasive and ubiquitous mean "existing everywhere." Pervasive computing devices are completely connected and constantly available. 24 Pervasive Computing • Industry revolution vs information revolution 25 Pervasive Computing • Devices Pervasive Computing • Principles – Decentralization • based on distributed systems. • with information synchronization. • devices and applications are embedded into wireless networking infrastructure. – Diversification • should target on different users with different needs. • must be able to manage the diversity. – Connectivity • boundless connectivity. – Simplicity • convenient and intuitive to use. • good and mature human computer interface. 27 Pervasive Computing • The wearable computer project MicroOptical display IR tag reader Internet appliance Body bus junction 802.11 bridge Battery single Board computer Body network hub 28 Distributed Systems • A distributed system is a system supporting distributed computing. • There is no universal definition. • It is generally a collection of autonomous computers, connected together by some communication media, usually a network. • They are capable of sharing resources and capable of providing service for one another. • The processors cooperate to achieve an overall goal. • Users may view the resulting environment as a single computing facility. 29 Distributed Systems • Distributed hardware – Processors and memory are physically separated, connected only via communication media. • Distributed control – Each processor is autonomous, running its own program. – They cooperate together in a voluntary manner. • Distributed data – Data for a program may scatter around and need to be exchanged to carry out a task. • Resources sharing – Expensive resources can be shared among different users. 30 Distributed Systems • Openness – System is visible to user, and can be modified and extended when needs arise. – For example, Unix is an open system and IBM PC has an open architecture. • Concurrency – Processors are autonomous and running concurrently. – Several jobs may be executed simultaneously. • Scalability – It is relatively easy to build a large system using similar approach to build a small system. – For example, Internet is built from smaller networks. 31 Distributed Systems • Fault tolerance – Processors more available (high availability), independent failure mode and preferably graceful degradation. – System can still function when some parts are down. • Transparency – User should not perceive the system as being composed of different parts and the lower level of functionality must be concealed. – For example, send/receive using a socket should not be concerned with data link and network connections. – Forms of transparency include access, location, concurrency, replication, failure, migration, performance, scaling. 32 New Features in Mobile Computing • Limited asymmetric bandwidth and high latency – Wireless channels are of limited bandwidth and asymmetric. – Perhaps of speed of grade of modems. • Weak connectivity and low reliability – Disconnection to channels can easily occur (planned or unplanned) and can be prolonged. – Messages may be lost with much higher probability. • Low processing power and energy – Battery is expensive and limited. – Screen or display is small. • Mobility of devices – Need to track location of devices and to provide proper services. – Invalidation to data upon change of location. • Low physical security – Mobile devices are easily lost, broken or stolen. • High degree of heterogeneity – Devices are very different in nature, e.g., Palm and Pocket PC are programmed differently, worse for embedded systems and devices. 33 Objectives of Mobile Computing • • • • • • • • To run existing distributed applications To provide distributed services To share data and resources To maintain efficiency To keep communication and operational cost down To conserve energy To achieve consistency among views of different users To be scalable in supporting numerous users 34 New Solutions to Old Problems • Solve problems in distributed systems – – – – – – – – – – – – Hardware and computer architecture Communication architecture and protocols Distributed operating systems Synchronization need File systems Databases systems Real-time processing Multimedia support with QoS Dynamic system reconfiguration Security Application requirement and design User interfaces design (on mobile devices) 35 Mobile Computing Architecture • Fixed network can be dedicated proprietary network for the mobile system. • Fixed network can also be the Internet or Intranet. • Infrastructured Systems – MSS (mobile support station, or base station) + – MU (Mobile unit, mobile station, mobile client) – WLAN, Cellular Net., etc. • Ad hoc systems – Mobile nodes + mobile nodes – MANET, WSN, VANET, etc. 36 Mobile Computing Architecture Server MU (mobile unit) MSS Fixed network (mobile support station) Wireless radio cell (19.2Kbps) WLAN 37 Applications • Personal applications – – – – – Web and email access. Personal information management. Personalized use of computer resources. Weather and traffic report. Network games. • Commercial applications – – – – – – – personal/tourism personal logistics/tourism personal finance Stock price quotation. Inventory control for traveling salesperson. e-commerce/finance finance Banking activities. tourism Bus-stop information kiosk at major bus terminals. Push-based advertisement on vehicle. e-commerce/tourism e-coupon. e-commerce Generic M-commerce applications. 38 Location Tracking • Active badge/RFID card with sensor technology – An early application of sensor technology in location tracking, developed by AT&T Cambridge Lab, for tracking and locating of individuals within a building. – Each building office is equipped with one or more networked sensors to detect these transmission signals. • Biometrics cards with bluetooth and RFID deployed at US Homeland Security Office May 2005. – Requirement: strong resistance to terrorist exploitation and rapid electronic authentication. – Could Hong Kong smart ID do that? – Problem: signal could be detected. 39 Radio-frequency identification (RFID) is the wireless use of electromagnetic fields to transfer data, for the purposes of automatically identifying and tracking tags attached to objects. 40 Location-Awareness • Location and mobility are the two major factors to be capitalized in a mobile application. • Applications can be based on the current location of a user. • Example – Emergency vehicle routing to caller of 999. – Deliver me a pizza as I am hungry! – Deliver value-added information based on current position. • Targeted advertisement to customer: E-coupon. – Logistics arrangement can be made based on location. • Send the goods to an alternative location if traffic jam is out-ofcontrol for receiving the goods. 41 Context-Awareness • A context-aware application is an application that adapts its behavior to a changing environment. • It needs to gather contextual information about its environment, usually through the use of sensors. • User does not need to give all information and the application should try to figure out the rest. • The follow-me type of applications: – Application knows the location of a user: • Smart map (Telenor Research) that always maintain the current user position at center. • Nearest restroom/toilet depends on gender. – When in a room, system can look up user profile for preferred room setting, or mode of operation for a speaker. Context vs. Location? 42 Context-Awareness Context vs. Location? 43 Intelligent Home • Intelligent home networking system with general technology – Use mobile phone technology to instruct a home control computer for home automation equipment. WiMAX (802.16), 802.11, Bluetooth etc. Transmit signal and control electronic devices via power line. Smart TV 44 Applications of Mobile Computing • Instant messaging? – 10 million iMode users in Japan since 18 months of introduction, also used by Greece Olympics. – 15.6 billion SMS messages in China January 2004. • Mobile games? – $9 billion sold in 2004. • Mobile web access? – WAP, iMode, WWW – How to resolve the bandwidth problem? 3G?4G? • Location-dependent services? – Sensor network infrastructure cost? • Context-aware services? – Locating a best restaurant closest by sensing e-cash in e-wallet and dining preference. • How can the communication infrastructure match with the application functionality and bandwidth / mobility requirement? – High bandwidth can be resulted, using pico-cells, but the client movement speed must be limited. 45 Bandwidth Requirement 3G wireless LAN current Ethernet 46 Asynchronous Transfer Mode Asynchronous Transfer Mode (ATM) is "a telecommunications concept defined by ANSI and ITU standards for carriage of a complete range of user traffic, including voice, data, and video signals". ATM was developed to meet the needs of the Broadband Integrated Services Digital Network, as defined in the late 1980s, and designed to unify telecommunication and computer networks. 47 Asynchronous Transfer Mode It was designed for a network that must handle both traditional high-throughput data traffic (e.g., file transfers), and real-time, low-latency content such as voice and video. The reference model for ATM approximately maps to the three lowest layers of the ISO-OSI reference model: network layer, data link layer, and physical layer. ATM is a core protocol used over the backbone of the public switched telephone network (PSTN) and Integrated Services Digital Network (ISDN) 48 Smartphone OS Market Share The largest shareholder is Android Operating System 49 Smartphone OS Market Share 2009 50 Smartphone OS Market Share 51 Java Platform, Micro Edition, or Java ME, is a Java platform designed for embedded systems (mobile devices are one kind of such systems). Target devices range from industrial controls to mobile phones (especially feature phones) and set-top boxes. Java ME was formerly known as Java 2 Platform, Micro Edition (J2ME). 52 WiMAX (Worldwide Interoperability for Microwave Access) is a family of wireless communications standards initially designed to provide 30 to 40 megabit-per-second data rates, with the 2011 update providing up to 1 Gbit/s for fixed stations. The name "WiMAX" was created by the WiMAX Forum, which was formed in June 2001 to promote conformity and interoperability of the standard. The forum describes WiMAX as "a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL". IEEE 802.16m or WirelessMAN-Advanced is a candidate for the 4G, in competition with the LTE Advanced standard. 53 New Forms of Computing • Distributed Computing (Client/Server) • • • • • • Wireless Computing Nomadic Computing Mobile Computing Ubiquitous Computing Pervasive Computing Invisible Computing 54 Mobile Computing • Using: – small size portable computers, hand-helds, MNC, and other small wearable devices, • To run stand-alone applications (or access remote applications) via: – wireless networks: IR, BlueTooth, W-LANs, Cellular, W-Packet Data networks, etc. • By: – nomadic and mobile users (animals, agents, trains, cars, cell phones, ….) 55 Nomadic, Mobile & Ubiquitous No Network Fixed Network Fixed Wireless Network Nomadic Computing Wireless Network (A) Wireless Network (B) Mobile Computing Ubiquitous Computing 56 Impressive Wireless Infrastructure! Global Satellite Suburban Urban In-Building Micro-Cell Macro-Cell Pico-Cell dik © In-Room (BlueTooth) 57 Wireless Network Convergence Mobility 2G/3G Mobility-Bandwidth Trade-off Global National 1-7 GHz GSM 0.1-2 GHz D-AMPS/IS-95 UMTS 0.1-2.3 GHz Regional 2-4 GHz Metropolitan Campus Office 2-7 GHz DECT WLAN >2 GHz Room DECT 10K 20-50 GHz 100K 1M 10M 100M 1G Bandwidth 58 UMTS: Universal Mobile Telecomm. Standard • Global seamless operation in multi-cell environment (SAT, macro, micro, pico) • Global roaming: multi-mode, multi-band, lowcost terminal, portable services & QoS • High data rates at different mobile speeds: 144kbps at vehicular speed (80km/h), 384 kbps at pedestrian speed, and 2Mbps indoor (office/home) • Multimedia interface to the internet • Based on core GSM, conforms to IMT-2000. Deployment as early as 2002. ITU IMT IMT-2000 FPLMTS ETSI SMG UMTS 59 Wireless Network Overlay Global Satellite Suburban Urban In-Building Micro-Cell Macro-Cell Pico-Cell dik © 60 Beneficiaries of Ubiquitous Computing Internet Intranet • Commuters • Travelers • Stock traders • Medical • Law enforcement • Package delivery • Education • Insurance • Emergency • Trucking • Intelligence • Military Adhoc network Servers Clients 61 Limitations of the Mobile Environment Limitations of the Wireless Network heterogeneity of fragmented networks frequent disconnections limited communication bandwidth Limitations Imposed by Mobility Limitations of the Mobile Computer 62 Frequent Disconnections Handoff blank out (>1ms for most cellulars) Drained battery disconnection Battery recharge down time Voluntary disconnection (turned off to preserve battery power, also off overnight) Theft and damage (hostile environment) Roam-off disconnections 63 Limited Communication Bandwidth Orders of magnitude slower than fixed network Higher transmission bit error rates (BER) Uncontrolled cell population Difficult to ensure Quality of Service (QoS) Availability issues (admission control) Asymmetric duplex bandwidth Limited communication bandwidth exacerbates the limitation of battery lifetime. 64 Limitations of the Mobile Computer Short battery lifetime (max ~ 5 hours) Subject to theft and destruction => unreliable Highly unavailable (normally powered-off to conserve battery) Limited capability (display, memory, input devices, and disk space) Lack of de-facto general architecture: handhelds, communicators, laptops, and other devices 65 Limitations Imposed by Mobility Lack of mobility-awareness by applications inherently transparent programming model (object-, components-oriented, but not aspect-oriented) lack of environment test and set API support Lack of mobility-awareness by the system network: existing transport protocols are inefficient to use across heterogeneous mix of fixed/wireless networks session and presentation: inappropriate for the wireless environment and for mobility operating systems: lack of env. related conditions and signals client/server: unless changed, inappropriate and inefficient 66 Evolution of Wireless LAN • In late 1980s, vendors started offering wireless products, which were to substitute the traditional wired LAN (Local Area Network) products. • The idea was to use a wireless local area network to avoid the cost of installing LAN cabling and ease the task of relocation or otherwise modifying the network's structure. 67 Evolution of Wireless LAN Cont. • The question of interoperability between different wireless LAN products became critical. • IEEE standard committee took the responsibility to form the standard for WLAN. • As a result IEEE 802.11 series of standards emerged. 68 Evolution of Wireless LAN Cont. • WLAN uses the unlicensed Industrial, Scientific, and Medical (ISM) band that different products can use as long as they comply with certain regulatory rules • WLAN is also known as Wireless Fidelity or WiFi in short • There are many products which use these unlicensed bands along with WLAN. 69 Evolution of Wireless LAN Cont. • Examples could be cordless telephone, microwave oven etc. • There are 3 bands within the ISM bands. – These are 900-MHz ISM band, which ranges from 902 to 928 MHz; – 2.4-GHz ISM band, which ranges from 2.4 to 2.4853 GHz; and – the 5.4 GHz band, which range from 5.275 to 5.85 GHz. • WLAN uses 2.4 GHz and 5.4 GHz bands. • WLAN works both in infrastructure mode and ad hoc mode 70 Evolution of Wireless PAN • Techniques for WPANs are infrared and radio waves. • Most of the Laptop computers support communication through infrared, for which standards have been formulated by IrDA (Infrared Data Associationwww.irda.org). • Through WPAN, a PC can communicate with another IrDA device like another PC or a Personal Digital Assistant (PDA) or a Cellular phone. 71 Evolution of Wireless PAN Cont. • The other best known PAN technology standard is Bluetooth. • Bluetooth uses radio instead of infrared. • It offers a peak over the air speed of about 1 Mbps over a short range of about 10 meters. • The advantage of radio wave is that unlike infrared it does not need a line of sight. • WPAN works in ad hoc mode only 72 MOBILE COMPUTING • Mobile computing can be defined as a computing environment over physical mobility. • The user of a mobile computing environment will be able to access data, information or other logical objects from any device in any network while on the move. 73 MOBILE COMPUTING Cont. • Mobile computing system allows a user to perform a task from anywhere using a computing device in the public (the Web), corporate (business information) and personal information spaces (medical record, address book). 74 MOBILE COMPUTING Cont. • Mobile computing is used in different contexts with different names. The most common names are: – Mobile Computing: • The computing environment is mobile and moves along with the user. • This is similar to the telephone number of a GSM (Global System for Mobile communication) phone, which moves with the phone. • The offline (local) and real-time (remote) computing environment will move with the user. • In real-time mode user will be able to use all his remote data and services online. 75 MOBILE COMPUTING Cont. – Anywhere, Anytime Information: This is the generic definition of ubiquity, where the information is available anywhere, all the time. – Virtual Home Environment: (VHE) is defined as an environment in a foreign network such that the mobile users can experience the same computing experience as they have in their home or corporate computing environment. • For example, one would like to put ones room heater on when one is about 15 minutes away from home. 76 MOBILE COMPUTING Cont. – Nomadic Computing: The computing environment is nomadic and moves along with the mobile user. • This is true for both local and remote services. – Pervasive Computing: A computing environment, which is pervasive in nature and can be made available in any environment. – Ubiquitous Computing: A disappearing (nobody will notice its presence) everyplace computing environment. User will be able to use both local and remote services. 77 MOBILE COMPUTING Cont. – Global Service Portability: Making a service portable and available in every environment. Any service of any environment will be available globally. – Wearable Computers: Wearable computers are those computers that may be adorned by humans like a hat, shoe or clothes (these are wearable accessories). 78 Mobile Computing Functions • We can define a computing environment as mobile if it supports one or more of the following characteristics: • User Mobility: – User should be able to move from one physical location to another location and use the same service. – The service could be in the home network or a remote network. – Example could be a user moves from London to New York and uses Internet to access the corporate application the same way the user uses in the home office. 79 Mobile Computing Functions Cont. • Network Mobility: – User should be able to move from one network to another network and use the same service. – Example could be a user moves from Hong Kong to New Delhi and uses the same GSM phone to access the corporate application through WAP (Wireless Application Protocol). In home network he uses this service over GPRS (General Packet Radio Service) whereas in Delhi he accesses it over the GSM network. 80 Mobile Computing Functions Cont. • Bearer Mobility: – User should be able to move from one bearer to another and use the same service. – Example could be a user was using a service through WAP bearer in his home network in Bangalore. He moves to Coimbatore, where WAP is not supported, he switch over to voice or SMS(Short Message Service) bearer to access the same application. 81 Mobile Computing Functions Cont. • Device Mobility: – User should be able to move from one device to another and use the same service. – Example could be sales representatives using their desktop computer in home office. During the day while they are on the street they would like to use their Palmtop to access the application. 82 Mobile Computing Functions Cont. • Session Mobility: – A user session should be able to move from one useragent environment to another. – Example could be a user was using his service through a CDMA (Code Division Multiple Access) IX network. The user entered into the basement to park the car and got disconnected from his CDMA network. User goes to home office and starts using the desktop. The unfinished session in the CDMA device moves from the mobile device to the desktop computer. 83 Mobile Computing Functions Cont. • Service Mobility: – User should be able to move from one service to another. – Example could be a user is writing a mail. To complete the mail user needs to refer to some other information. In a desktop PC, user simply opens another service (browser) and moves between them using the task bar. User should be able to switch amongst services in small footprint wireless devices like in the desktop. 84 Mobile Computing Functions Cont. • Host Mobility: – The user device can be either a client or server. – When it is a server or host, some of the complexities change. – In case of host mobility the mobility of IP needs to be taken care of. 85 Logical Functions of Mobile Computing • The mobile computing functions can be logically divided into following major segments: 1. User with device: • The user device, this could be a fixed device like desktop computer in office or a portable device like mobile phone. • Example: laptop computers, desktop computers, fixed telephone, mobile phones, digital TV with set-top box, palmtop computers, pocket PCs, two way pagers, handheld terminals, etc. 86 Logical Functions of Mobile Computing 2. Network: • • Whenever a user is mobile, he will be using different networks at different places at different time. Example: GSM, CDMA, iMode, Ethernet, Wireless LAN, Bluetooth etc. 87 Logical Functions of Mobile Computing 3.Gateway: • This is required to interface different transport bearers. • These gateways convert one specific transport bearer to another transport bearer. • Example: From a fixed phone (with voice interface) we access a service by pressing different keys on the telephone. These keys generate DTMF (Dual Tone Multi Frequency) signals. • These analog signals are converted into digital data by the IVR (Interactive Voice Response) gateway to interface with a computer application. • Other examples will be WAP gateway, SMS gateway88etc. Logical Functions of Mobile Computing 4. Middleware: • • • This is more of a function rather than a separate visible node. In the present context middleware handles the presentation and rendering of the content on a particular device. It will also handle the security and personalization for different users 89 Logical Functions of Mobile Computing 5. Content: • • • • This is the domain where the origin server and content is. This could be an application, system, or even an aggregation of systems. The content can be mass market, personal or corporate content. Origin server will have some means to accessing the database and the storage devices 90