Options for PBCC 22 Proposal January 2001 doc.: IEEE 802.11-01/066 January 2001 Options for PBCC 22 Proposal Anuj Batra Ph.D., Chris Heegard Ph.D., Eric J. Rossin Ph.D., Matthew B. Shoemake Ph.D., 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 Anuj Batra et al., Texas Instruments

Increasing Throughput with a High Performance Preamble January 2001 Increasing Throughput with a High Performance Preamble Anuj Batra et al., Texas Instruments

Current Preamble and Header (P/H) January 2001 doc.: IEEE 802.11-01/066 January 2001 Current Preamble and Header (P/H) Long PLCP PPDU Format: PLCP PREAMBLE 144 BITS @ 1Mbps PLCP HEADER 48 BITS @ 1Mbps PSDU 192 ms Short PLCP PPDU Format: SHORT PLCP PREAMBLE 72 BITS @ 1Mbps SHORT PLCP HEADER 48 BITS @ 2Mbps PSDU 96 ms Preamble and header contains no information - overhead Anuj Batra et al., Texas Instruments Anuj Batra et al., Texas Instruments

Motivation for a Shorter P/H January 2001 doc.: IEEE 802.11-01/066 January 2001 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 Anuj Batra et al., Texas Instruments

New High Performance P/H January 2001 doc.: IEEE 802.11-01/066 January 2001 New High Performance P/H ~38 ms TIMING SYNC 88 symbols @ 11Msps FRAME SYNC 72 symbols @ 11Msps CHANNEL EST 168 symbols @ 11Msps HEADER 48 BITS @ 5.5Mbps PSDU 5.5 – 33 Mbps PREAMBLE 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 Anuj Batra et al., Texas Instruments

Key Points of High Performance P/H January 2001 doc.: IEEE 802.11-01/066 January 2001 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 Anuj Batra et al., Texas Instruments

Throughput with ACK January 2001 doc.: IEEE 802.11-01/066 January 2001 Anuj Batra et al., Texas Instruments Anuj Batra et al., Texas Instruments

Throughput with NO ACK January 2001 doc.: IEEE 802.11-01/066 Anuj Batra et al., Texas Instruments Anuj Batra et al., Texas Instruments

January 2001 doc.: IEEE 802.11-01/066 January 2001 Increasing the Data Rate to 33Mbps in Wireless Ethernet via Clock Switching Anuj Batra et al., Texas Instruments Anuj Batra et al., Texas Instruments

January 2001 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