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Suggested Options to the Texas Instruments Proposal for IEEE 802.11g High-Rate Standard

Suggested Options to the Texas Instruments Proposal for IEEE 802.11g High-Rate Standard. Anuj Batra PhD, Chris Heegard PhD, Eric Rossin PhD, and Matthew B. Shoemake PhD. Texas Instruments 141 Stony Circle, Suite 130 Santa Rosa California 95401 (707) 521-3060, heegard@ti.com.

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Suggested Options to the Texas Instruments Proposal for IEEE 802.11g High-Rate Standard

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  1. Suggested Options to the Texas Instruments Proposal for IEEE 802.11g High-Rate Standard Anuj Batra PhD, Chris Heegard PhD, Eric Rossin PhD, and Matthew B. Shoemake PhD Texas Instruments 141 Stony Circle, Suite 130 Santa Rosa California 95401 (707) 521-3060, heegard@ti.com Anuj Batra et al., Texas Instruments

  2. Increasing Throughput with a High Performance Preamble Anuj Batra et al., Texas Instruments

  3. PLCP PREAMBLE 144 BITS @ 1Mbps PLCP HEADER 48 BITS @ 1Mbps PSDU PSDU 192 ms SHORT PLCP PREAMBLE 72 BITS @ 1Mbps SHORT PLCP HEADER 48 BITS @ 2Mbps 96 ms Current Preamble and Header (P/H) • Long PLCP PPDU Format: • Short PLCP PPDU Format: • Note that the preamble and header contain no information Anuj Batra et al., Texas Instruments

  4. Percent Overhead PSDU size (bytes) Percent Overhead for Long P/H Anuj Batra et al., Texas Instruments

  5. Percent Overhead PSDU size (bytes) Percent Overhead for Short P/H Anuj Batra et al., Texas Instruments

  6. Motivation for a Shorter P/H • For short PSDUs, preamble and header spans a large portion of the packet • Large P/H wastes valuable resources and decreases the network throughput • Can reduce overhead by: • defining a new preamble, and • increasing the data rate for the header Anuj Batra et al., Texas Instruments

  7. PREAMBLE TIMING SYNC 96 symbols @ 11Msps FRAME SYNC 64 symbols @ 11Msps HEADER 48 BITS @ 5.5Mbps PSDU CHANNEL EST 168 symbols @ 11Msps 38.55 ms New High Performance P/H • Timing Synchronization Sequence: • tone that alternates between (1+j) and (-1-j) • allows for easy detection of packet, timing, carrier frequency offset • need clocks to be locked • Frame Synchronization Sequence: composed of PN sequences • fix location within packet • Channel Estimation Sequence: deterministic sequernce • example: first 168 symbols of a length 255 PN sequence Anuj Batra et al., Texas Instruments

  8. PSDU PSDU ACK P/H P/H P/H Total time network throughput = time to transmit information total time Simulation: Network Throughput • Assumed a back-off time of zero to demonstrate the effect that the preamble size has on network throughput • Calculated increase in throughput for new P/H over Long P/H and Short P/H for various data rates SIFS DIFS BACKOFF Anuj Batra et al., Texas Instruments

  9. Throughput Increase for 5.5 Mbps Anuj Batra et al., Texas Instruments

  10. Throughput Increase for 11.0 Mbps Anuj Batra et al., Texas Instruments

  11. Throughput Increase for 16.5 Mbps Anuj Batra et al., Texas Instruments

  12. Throughput Increase for 22.0 Mbps Anuj Batra et al., Texas Instruments

  13. Throughput Increase for 33.0 Mbps Anuj Batra et al., Texas Instruments

  14. Summary • Proposed a new preamble and header, which: • decreases overhead, and • increases network throughput for short packets • Results: • 5.5 Mbps: 120%+ over Long P/H ,40%+ over Short P/H • 11.0 Mbps: 150%+ over Long P/H, 60%+ over Short P/H • 16.5 Mbps: 165%+ over Long P/H, 65%+ over Short P/H • 22.0 Mbps: 180%+ over Long P/H , 70%+ over Short P/H • 33.0 Mbps: 200%+ over Long P/H , 75%+ over Short P/H Anuj Batra et al., Texas Instruments

  15. Increasing the Data Rate to 33Mbps in Wireless Ethernet via Clock Switching Anuj Batra et al., Texas Instruments

  16. Introduction • The existing IEEE 802.11b standard, and the TI proposed 22 Mbps extension to the standard, is based upon an 11 Msps symbol rate and a bandwidth occupancy of 20 MHz. In terms of modern digital communications techniques such as pulse shaping and adaptive equalization, a more aggressive symbol rate in the same bandwidth is practical. However, in order to deal with inter-operability with existing networks, the structure of the preamble, including the symbol rate of the preamble, must not change. A viable method to address these issues is to transmit an 11Msps preamble followed by a higher symbol rate encoded data rate. Means and issues involving the switch in the clock are addressed in this presentation. The suggested increase in rate by 50% to 16.5 Msps yields a data rate of 33 Mbps. Anuj Batra et al., Texas Instruments

  17. Pulse Shaping Anuj Batra et al., Texas Instruments

  18. Eye Diagram Anuj Batra et al., Texas Instruments

  19. Clock Switching Anuj Batra et al., Texas Instruments

  20. Clock Switching from 11MHz to 16.5 MHz with no (0//0) Guard Band Anuj Batra et al., Texas Instruments

  21. Clock Switching from 11MHz to 16.5 MHz with (2//3) Guard Band Anuj Batra et al., Texas Instruments

  22. Clock Switching from 11MHz to 16.5 MHz with (4//6) Guard Band Anuj Batra et al., Texas Instruments

  23. Packet Structure • Packet Structure without Clock Switching Anuj Batra et al., Texas Instruments

  24. Packet Structure (cont.) • Packet Structure with Clock Switching Anuj Batra et al., Texas Instruments

  25. Throughput with Ack Anuj Batra et al., Texas Instruments

  26. Throughput without Ack Anuj Batra et al., Texas Instruments

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