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Wireless Application Protocol

Wireless Application Protocol. Week#1. Wireless Application Protocol. Today Lecture Introduction to wireless communication Why Wireless communication? Challenges in wireless communication. Human Requirements Wireless vs Mobile Types of Wireless Communication

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Wireless Application Protocol

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  1. Wireless Application Protocol Week#1

  2. Wireless Application Protocol • Today Lecture • Introduction to wireless communication • Why Wireless communication? • Challenges in wireless communication. • Human Requirements • Wireless vs Mobile • Types of Wireless Communication • Limitations and Difficulties of Wireless Technologies

  3. What is wireless communication? • A wireless network enables people to communicate and access applications and information without wires. This provides freedom of movement and the ability to extend applications to different parts of a building, city, or nearly anywhere in the world. • Transfer of voice or data without wires. • Transmitting and receiving voice or data using electromagnetic waves • in open space • The information from sender to receiver is carrier over a well-defined frequency band (channel) • Each channel has a fixed frequency bandwidth and Capacity (bit-rate) • Different channels can be used to transmit information in parallel and independently.

  4. Why Wireless communication? Freedom from wires – No cost of installing wires or rewiring – No bunches of wires running here and there – communications without physical connection setup, e.g., Bluetooth,WiFi Global Coverage – Communications can reach where wiring is infeasible or costly, e.g., rural areas, old buildings, battlefield, vehicles, outer space (through Communication Satellites)

  5. Challenges in wireless communication Stay Connected – Roaming allows flexibility to stay connected anywhere and any time – Rapidly growing market attests to public need for mobility and uninterrupted access Flexibility – Services reach you wherever you go (Mobility). E.g, you don’t have to go to your lab to check your mail – Connect to multiple devices simultaneously (no physical connection required)

  6. Techanical Challenges in wireless communication Efficient Hardware – Low power Transmitters, Receivers – Low Power Signal Processing Tools Efficient use of finite radio spectrum – Cellular frequency reuse, medium access control protocols,... Integrated services – voice, data, multimedia over a single network – service differentiation, priorities, resource sharing,...

  7. Challenges (2) • Network support for user mobility (mobile • scenarios) • – location identification, handover,... • Maintaining quality of service over unreliable links • Connectivity and coverage • (internetworking) • Cost efficiency

  8. Challenges (3) • Fading • Multipath • Higher probability of data corruption • – Hence, need for stronger channel codes • Need for stronger Security mechanisms • – privacy, authentication,…

  9. Human Requirements • Delay • Packet Loss • BER • Data Rate • Traffic

  10. Wireless vs Mobile • NOTE : Wireless does not necessarily mean mobile • Wireless Systems may be • – Fixed (e.g., Metropolitan Area Network) • – Portable (e.g., wireless interaction between TV and VCR) • – Mobile (e.g., mobile phone)

  11. Wired Vs. Wireless Communication Each cable is a different channel One media (cable) shared by all Highsignal attenuation Signal attenuation is low High interference noise; co-channel interference; adjacent channel interference No interference

  12. Why Wireless Networks • Cabling is sometimes impossible • – Even if possible, cabling is quite expensive • • Modern work conditions require the • flexibility of installation • No cost for re-installation or rewiring • Wireless is convenient and not too expensive • Roaming allows flexibility • – Stay connected anywhere and any time • Rapid market growth and application demands • – uninterrupted, fast access regardless of the application • • Consumers and businesses are willing to pay for it

  13. Why go wireless ? • Advantages • Sometimes it is impractical to lay cables • User mobility • Cost • Limitations • Bandwidth • Fidelity • Power • (In) security

  14. Types of Wireless Communication (1) • Radio Transmission • – Easily generated, omni-directionally travel long • distances, easily penetrate buildings • – Problems: • • frequency-dependent • • relative low bandwidth for data communication • • tightly licensed by the governments • Microwave Transmission • – Widely used for long distance communication • – Gives a high S/N ratio, relatively inexpensive • – Problems: • • don’t pass through buildings well • • weather and frequency-dependent

  15. Types of Wireless Communication (2) • Infrared and Millimeter Waves • – Widely used for short-range communication • – Unable to pass through solid objects • – Used for indoor wireless LANs, not for outdoors • Lightwave Transmission • – Unguided optical signal, such as laser • – Connect two LANs in two buildings via laser • mounted on their roof • – Unidirectional, easy to install, don’t require license • – Problems: • • unable to penetrate rain or thick fog • • laser beam can be easily diverted by turbulent air

  16. Limitations and Difficulties of Wireless Technologies • Wireless is convenient and less expensive • Limitations and political and technical difficulties inhibit wireless technologies • Lack of an industry-wide standard • Device limitations • E.g., small LCD on a mobile telephone can only displaying a few lines of text • E.g., browsers of most mobile wireless devices use wireless markup language (WML) instead of HTML

  17. Limitations and Difficulties of Wireless Technologies • Technology is still expensive • – Newer technologies are much expensive • • Range is reduced as much as the speed is increased • • Problems of security and confidentiality • Errors occur much more than in wired networks • Interference with other systems • • Detection of collision is impossible

  18. Wireless Systems: Range Comparison Mobile Telephony, WLL MW Radio SW Radio Satellite Links FM Radio WLANs Blueooth IR 1 m 10 m 100 m 1 Km 10 Km 100 Km 1,000 Km

  19. User Growth

  20. Traffic Growth

  21. A Simplified Wireless CommunicationSystem Representation

  22. Mobile Wireless Networks • What must a mobile network provide ? • – Connectivity with mobility • – Cost-effective sharing of bandwidth • – Performance • • How are mobile networks designed ? • – Layering • – Protocols • – Standards

  23. Role of Standards • Provide (the hope of) interoperability • – Equipment from different vendors • – Existing protocols and software • • Volume in the marketplace • – Broader support by equipment/software vendors Reduced prices

  24. Classification of WirelessNetworks • Mobility: fixed wireless or mobile • • Communication: Analog or digital • • Topology/Infrastructure: Ad hoc • (decentralized) or centralized (base stations) • • Services: voice or data • • Ownership: public or private

  25. Classification of WirelessNetworks • Area: wide (WAN), metropolitan (MAN), • local (LAN), or personal (PAN) area networks • • Medium: Switched (circuit- or • Packet switched) • or broadcast • • Data Rate: Low bit-rate (voice grade) or high • bit-rate (video, multimedia) • • Placement: satellite

  26. Current Wireless Systems • Cellular Systems • Wireless LANs • Satellite Systems • Wireless PANs (bluetooth)

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