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An introduction to different UWB MAC protocols

An introduction to different UWB MAC protocols. Thomas Benjamin Hunziger Shanghai Jiao Tong University hunziger@gmx.de. Outline. Introduction Using existing MAC in UWB CSMA/CA TDMA Other approaches DCC-MAC Conclusion. History of UWB. Guglielmo Marconi, December 12, 1901, “S”

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An introduction to different UWB MAC protocols

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  1. An introduction to different UWB MAC protocols Thomas Benjamin Hunziger Shanghai Jiao Tong University hunziger@gmx.de

  2. Outline • Introduction • Using existing MAC in UWB • CSMA/CA • TDMA • Other approaches • DCC-MAC • Conclusion

  3. History of UWB • Guglielmo Marconi, December 12, 1901, “S” • Experiment was doubted • January 18, 1903 • Greetings from Theodore Roosevelt to King Edward VII • February 14, 2002, FCC authorizes UWB.

  4. What is UWB? • FCC Definition • More than 25% of the center frequency • Or bandwidth greater than 500 MHz • Frequency Range from 3.1GHz – 10.6 GHz

  5. UWB Monopulse Time (ns)

  6. UWB advantages • Low power consumption • Low detection • High immunity to multipath-fading effects • Ability to penetrate walls • Availability of precise location information

  7. UWB Disadvantages • Difficult to generate extremely short pulses • High Acquisition Time (1ms) • External Interference from other Systems

  8. UWB Applications • Ground-penetrating radars • Imaging systems • Vehicular radars • Wireless offices and homes • Identification tags • Location-tracking • Security systems • Short range voice, data and video • Etc…

  9. UWB Networks

  10. Which MAC Protocol? • Old or New • TDMA, CSMA/CA vs DCC-MAC • Centralized or Distributed • How to find out?

  11. Existing MAC Protocols • Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) • Random Access Protocol • Virtual Carrier Sense Mechanism • Time Division Multiple Access (TDMA) • Shared bandwidth in Time (timeslots) • Frames (Set of timeslots) • Requires perfect synchronization

  12. Performance • Scenario • 20 nodes distributed randomly • Rectangular area of 100m* 100m • All homogenous nodes • Each node enough transmission power to connect the network. • Only one wide channel available for all communication

  13. Acquisition Time Time for transmitter and receiver to achieve bit synchronization. • UWB Acquisition Time ~1ms • NB Acquisition Time ~0.01ms

  14. Utilization & Throughput

  15. Comparison of Technologies

  16. DCC-MAC • New Approach • Fully Distributed • Pulse-Position Modulation (PPM) • Enhanced CDMA with Dynamic Channel Coding • “Private MAC”

  17. Performance

  18. Conclusion • Acquisition time is big problem in UWB. • Larger packet size? • Standard MAC protocols have to be adjusted in order to compete with new ones. • Better result with other approaches • DCC-MAC

  19. References • Jin Ding, L. Zhao, S.R. Medidi, and K.M. Sivalingam. MAC Protocols for Ultra-Wide-Band (UWB) Wireless Networks: Impact of Channel Acquisition Time. http://dawn.cs.umbc.edu/Papers/2002/ITCOM02-UWB.pdf , 2002 • Jean-Yves Le Boudec, Ruben Merz, Bozidar Radunovic, Joerg Widmer. A MAC protocol for UWB Very Low Power Mobile Ad-hoc Networks based on Dynamic Channel Coding with Interference Mitigation http://icwww.epfl.ch/publications/documents/IC_TECH_REPORT_200402.pdf , 2004 • Saad Biaz, Yiming Ji, A glance at MAC protocols for ultra widebandhttp://portal.acm.org/citation.cfm?id=986559 , 2004

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