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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, [email protected]

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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, [email protected]

Anuj Batra et al., Texas Instruments

increasing throughput with a high performance preamble

Increasing Throughput with a High Performance Preamble

Anuj Batra et al., Texas Instruments

current preamble and header p h

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

percent overhead for long p h

Percent Overhead

PSDU size (bytes)

Percent Overhead for Long P/H

Anuj Batra et al., Texas Instruments

percent overhead for short p h

Percent Overhead

PSDU size (bytes)

Percent Overhead for Short P/H

Anuj Batra et al., Texas Instruments

motivation for a shorter p h
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

new high performance p h

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

simulation network throughput

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

throughput increase for 5 5 mbps
Throughput Increase for 5.5 Mbps

Anuj Batra et al., Texas Instruments

throughput increase for 11 0 mbps
Throughput Increase for 11.0 Mbps

Anuj Batra et al., Texas Instruments

throughput increase for 16 5 mbps
Throughput Increase for 16.5 Mbps

Anuj Batra et al., Texas Instruments

throughput increase for 22 0 mbps
Throughput Increase for 22.0 Mbps

Anuj Batra et al., Texas Instruments

throughput increase for 33 0 mbps
Throughput Increase for 33.0 Mbps

Anuj Batra et al., Texas Instruments

summary
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

increasing the data rate to 33mbps in wireless ethernet via clock switching

Increasing the Data Rate to 33Mbps in Wireless Ethernet via Clock Switching

Anuj Batra et al., Texas Instruments

introduction
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

pulse shaping
Pulse Shaping

Anuj Batra et al., Texas Instruments

eye diagram
Eye Diagram

Anuj Batra et al., Texas Instruments

clock switching
Clock Switching

Anuj Batra et al., Texas Instruments

clock switching from 11mhz to 16 5 mhz with no 0 0 guard band
Clock Switching from 11MHz to 16.5 MHz with no (0//0) Guard Band

Anuj Batra et al., Texas Instruments

clock switching from 11mhz to 16 5 mhz with 2 3 guard band
Clock Switching from 11MHz to 16.5 MHz with (2//3) Guard Band

Anuj Batra et al., Texas Instruments

clock switching from 11mhz to 16 5 mhz with 4 6 guard band
Clock Switching from 11MHz to 16.5 MHz with (4//6) Guard Band

Anuj Batra et al., Texas Instruments

packet structure
Packet Structure
  • Packet Structure without Clock Switching

Anuj Batra et al., Texas Instruments

packet structure cont
Packet Structure (cont.)
  • Packet Structure with Clock Switching

Anuj Batra et al., Texas Instruments

throughput with ack
Throughput with Ack

Anuj Batra et al., Texas Instruments

throughput without ack
Throughput without Ack

Anuj Batra et al., Texas Instruments

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