Wireless Application Protocol           Week#1                                1
Wireless Application Protocol Today Lecture   Introduction to wireless communication   Why Wireless communication?   C...
What is wireless com m unication?   A wireless network enables people to communicate and access    applications and infor...
Why Wireless com m unication?Freedom from wires– No cost of installing wires or rewiring– No bunches of wires running here...
Challenges in wireless com m unicationStay Connected– Roaming allows flexibility to stay connected  anywhere and any time–...
Techanical Challenges in wireless             com m unication Efficient Hardware– Low power Transmitters, Receivers– Low P...
Challenges (2) Network support for user mobility (mobile scenarios) – location identification, handover,...  Maintaini...
Challenges (3)   Fading    Multipath    Higher probability of data corruption   – Hence, need for stronger channel cod...
H um an Requirem ents   D elay   Packet Loss   BER   D ata Rate   Traffic                                      9
Wireless vs Mobile NOTE : Wireless does not necessarily mean mobile Wireless Systems may be – Fixed (e.g., Metropolitan...
Wired Vs. Wireless Com m unication             Wired                                WirelessEach cable is a different chan...
Why Wireless Networks Cabling is som etim es im possible – Even if possible, cabling is quite expensive • Mod ern work ...
Why go wireless ? Ad vantages   ► S om etim es it is im practical to lay cables   ► User m obility   ► Cost Lim itations...
Types of Wireless Communication (1)   Radio Transmission   – Easily generated, omni-directionally travel long   distanc...
Types of Wireless Communication (2)   Infrared and Millimeter Waves   – Widely used for short-range communication   – U...
Limitations and Difficulties of Wireless                  Technologies Wireless is convenient and less expensive Limitat...
Limitations and Difficulties of Wireless                       Technologies Technology is still expensive – Newer techno...
Wireless S ystem s: Range Com parison1m   10 m   100 m     1 Km   10 Km       100 Km              1,000 Km                ...
User Growth              19
Traffic Growth                 20
A Simplified Wireless Communication      System Representation                                      21
Mobile Wireless Networks What must a mobile network provide ? – Connectivity with mobility – Cost-effective sharing of ...
Role of S tand ard s Provide (the hope of) interoperability – Equipment from different vendors – Existing protocols and...
Classification of Wireless                       Networks   Mobility: fixed wireless or mobile   • Communication: Analog...
Classification of Wireless                       Networks   Area: wid e (WAN), m etropolitan (MAN),   local (LAN), or pe...
Current Wireless Systems   Cellular Systems   Wireless LANs   Satellite Systems   Wireless PANs (bluetooth)           ...
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Week1

  1. 1. Wireless Application Protocol Week#1 1
  2. 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 2
  3. 3. What is wireless com m unication? 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. 3
  4. 4. Why Wireless com m unication?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 isinfeasible or costly, e.g., rural areas, old buildings,battlefield, vehicles, outer space (throughCommunication Satellites) 4
  5. 5. Challenges in wireless com m unicationStay 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) 5
  6. 6. Techanical Challenges in wireless com m unication Efficient Hardware– Low power Transmitters, Receivers– Low Power Signal Processing Tools Efficient use of finite radio spectrum– Cellular frequency reuse, medium access controlprotocols,... Integrated services– voice, data, multimedia over a single network– service differentiation, priorities, resource 6 sharing,...
  7. 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 7
  8. 8. Challenges (3) Fading Multipath Higher probability of data corruption – Hence, need for stronger channel codes Need for stronger Security mechanisms – privacy, authentication,… 8
  9. 9. H um an Requirem ents D elay Packet Loss BER D ata Rate Traffic 9
  10. 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) 10
  11. 11. Wired Vs. Wireless Com m unication Wired WirelessEach cable is a different channel One media (cable) shared by allSignal attenuation is low High signal attenuationNo interference High interference noise; co-channel interference; adjacent channel interference 11
  12. 12. Why Wireless Networks Cabling is som etim es im possible – Even if possible, cabling is quite expensive • Mod ern work cond itions require the flexibility of installation No cost for re-installation or rewiring Wireless is convenient and not too expensive Roaming allows flexibility – S tay connected anywhere and any tim e Rapid market growth and application demands – uninterrupted, fast access regardless of the application • Consumers and businesses are willing to pay for it 12
  13. 13. Why go wireless ? Ad vantages ► S om etim es it is im practical to lay cables ► User m obility ► Cost Lim itations ► Band wid th ► Fid elity ► Power ► (In) security 13
  14. 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 14
  15. 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 15
  16. 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 16
  17. 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 17
  18. 18. Wireless S ystem s: Range Com parison1m 10 m 100 m 1 Km 10 Km 100 Km 1,000 Km Mobile FM MW SW Satellite WLANs Telephony, Radio Radio Radio LinksIR Blueooth WLL 18
  19. 19. User Growth 19
  20. 20. Traffic Growth 20
  21. 21. A Simplified Wireless Communication System Representation 21
  22. 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 22
  23. 23. Role of S tand ard s 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 23
  24. 24. Classification of Wireless Networks 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 24
  25. 25. Classification of Wireless Networks Area: wid e (WAN), m etropolitan (MAN), local (LAN), or personal (PAN) area networks • Medium: S witched (circuit- or Packet switched ) or broad cast • Data Rate: Low bit-rate (voice grad e) or high bit-rate (vid eo, m ultim ed ia) • Placement: satellite 25
  26. 26. Current Wireless Systems Cellular Systems Wireless LANs Satellite Systems Wireless PANs (bluetooth) 26

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