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IT 644: Mobile Computing

This course on Mobile Computing explores various aspects of wireless networks, including cellular networks, wireless LANs, and ad hoc networks. Key topics include mobile applications, client-server adaptations, security, and energy efficiency. The impact of mobility on algorithms, limitations of mobile environments, and strategies for disconnected operations are also examined. Students will learn about critical mobile applications in emergency services, intelligent travel guides, and entertainment. The course addresses adaptations needed for mobile access to the World Wide Web.

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IT 644: Mobile Computing

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  1. IT 644: Mobile Computing Instructor: Sridhar Iyer http://www.it.iitb.ernet.in/~sri Course Page http://quark.it.iitb.ernet.in/~it644 Lecture Hours Tue: 9:30, Thu: 10:30, Fri: 8:30

  2. Course Outline • Wireless Networks • Cellular networks • Wireless LANs • Ad hoc networks • Satellite systems, … • Mobile Applications • Client-Server adaptations • Disconnected operations • Mobile agents • Data broadcasting • Wireless application protocol • Other Issues • Security • Energy efficiency • Impact of mobility on algorithms

  3. Wireless Networks • Need: Access computing and communication services, on the move • Infrastructure-based Networks • traditional cellular systems (base station infrastructure) • Wireless LANs • Infrared (IrDA) or radio links (Wavelan) • very flexible within the reception area; ad-hoc networks possible • low bandwidth compared to wired networks (1-10 Mbit/s) • Ad hoc Networks • useful when infrastructure not available, impractical, or expensive • military applications, rescue, home networking

  4. Limitations of Mobile Environments • Limitations of the Wireless Network • heterogeneity of fragmented networks • frequent disconnections • limited communication bandwidth • Limitations Imposed by Mobility • lack of mobility awareness by system/applications • route breakages • Limitations of the Mobile Computer • short battery lifetime • limited capacities

  5. Effect of Mobility on Protocol Stack • Application • new applications and adaptations • Transport • congestion and flow control • Network • addressing and routing • Link • media access and handoff • Physical • transmission errors and interference

  6. Mobile Applications • Vehicles • transmission of news, road condition etc • ad-hoc network with near vehicles to prevent accidents • Emergencies • early transmission of patient data to the hospital • ad-hoc network in case of earthquakes, cyclones • military ... • Traveling salesmen • direct access to central customer files • consistent databases for all agents • mobile office

  7. Mobile Applications • Web access • outdoor Internet access • intelligent travel guide with up-to-datelocation dependent information • Location aware services • find services in the local environment, e.g. printer • Information services • push: e.g., stock quotes • pull: e.g., nearest cash ATM • Disconnected operations • mobile agents, e.g., shopping • Entertainment • ad-hoc networks for multi user games

  8. Application Adaptations for Mobility • System-transparent, application-transparent • the conventional, “unaware” client/server model • System-aware, application-transparent • the client/proxy/server model • the disconnected operation model • System-transparent, application-aware • dynamic client/server model • data broadcasting/caching • System-aware, application-aware • the mobile agent model

  9. World Wide Web and Mobility • HTTP/ HTML have not been designed for mobile applications/devices • HTTP Characteristics • stateless, connection oriented overheads • big protocol headers, uncompressed content transfer • HTML Characteristics • designed for computers with “high” performance, color high-resolution display, mouse, hard disk • typically, web pages optimized for design, not for communication; ignore end-system characteristics • Adaptations for Mobile WWW • Enhanced browsers and/or servers • Client proxy: pre-fetching, caching, off-line use • Network proxy: adaptive content transformation for connections • Client and network proxy • New protocols/languages: WAP/WML

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