Options for PBCC 22 Proposal

1. Options for PBCC 22 Proposal Anuj Batra PhD, Chris Heegard PhD, Eric J. Rossin PhD, Matthew B. Shoemake PhD, and Srikanth Gummadi Texas Instruments 12500 TI Boulevard, MS 8653 Dallas, TX 75243 (214) 480-4220, batra@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: • Preamble and header contains no information - overhead Anuj Batra et al., Texas Instruments

4. Motivation for a Shorter P/H • For short packets: • 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

5. PREAMBLE TIMING SYNC 88 symbols @ 11Msps FRAME SYNC 72 symbols @ 11Msps HEADER 48 BITS @ 5.5Mbps CHANNEL EST 168 symbols @ 11Msps PSDU 5.5 – 33 Mbps ~38 ms New High Performance P/H • Timing Synchronization Sequence: tones • complex tone at f0 = ±8.25 MHz • allows for easy detection of packet, carrier frequency offset, symbol timing • requires that the clocks to be locked • Frame Synchronization Sequence: PN sequences • can be used to determine the location within packet • can also be used for receiver diversity – select the antenna with best gain • Channel Estimation Sequence: deterministic sequence • first 160 symbols of a length 255 PN sequence • sequence is generated by using a minimal polynomial over GF(4) Anuj Batra et al., Texas Instruments

6. Key Points of High Performance P/H • Increases throughput by reducing overhead • Designed to work at SNRs as low as 3–4 dB • Preamble can be used to estimate the channel • Supports most legacy rates: 5.5 and 11 Mbps • Also supports newer rates: 16.5, 22, 33 Mbps • High performance Preamble/Header can also be clocked at 16.5 MHz (more later) Anuj Batra et al., Texas Instruments

7. Throughput with ACK Anuj Batra et al., Texas Instruments

8. Throughput with NO ACK Anuj Batra et al., Texas Instruments

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

10. Clock Switching • 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. • Reference: IEEE 802.11-00/386 Anuj Batra et al., Texas Instruments