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Improving Single Stream Device Performance Using Protocol Assisted Switched Diversity

Improving Single Stream Device Performance Using Protocol Assisted Switched Diversity. Authors:. Date: 2007-11-14. AT&T. Florham Park, NJ. 973-236-6920. rrm@att.com. R. R. Miller. Motivation. Use of handheld equipment growing Battery life is important

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Improving Single Stream Device Performance Using Protocol Assisted Switched Diversity

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  1. Improving Single Stream Device Performance Using Protocol Assisted Switched Diversity Authors: Date: 2007-11-14 AT&T Florham Park, NJ 973-236-6920 rrm@att.com R. R. Miller R. R. Miller, AT&T

  2. Motivation • Use of handheld equipment growing • Battery life is important • Multiple receivers are more expensive and consume more power • Multimedia streaming demands better downstream PER to provide good user experience and less radio resource waste due to excessive repeats: Maximizing goodput is the focus • Build on Single Stream Subgroup considerations • Addresses PHY CIDs 1322 (previous draft) and 5444 (current draft) R. R. Miller, AT&T

  3. PASD Basics • Leverage modern signal processing techniques • Soft-symbol memory • Combining diversity (Maximal Ratio) • Hybrid ARQ • Use two antennas, but switch into single receiver • Synchronize switching with AP via protocol • Provide capability indication to AP that client is PASD-equipped • AP transmits multiple bursts, 1 each per client antenna • STA stores soft symbols from 1st burst (received via antenna 1) & 2nd burst (received via antenna 2) • STA processes 1st burst immediately • Cancel 2nd burst if 1st received OK (ACK immediately) • Else, STA performs MRC on stored 1st & 2nd bursts • STA returns ACK/NAK R. R. Miller, AT&T

  4. PASD Architecture R T Single Stream Client AP Antenna 1 Burst 1 M1 DEMOD A/D MRC M2 R Antenna 2 SISO PHY/MAC T Burst 2 ARQ Processor Burst 2 Simplified Implementation Diagram R. R. Miller, AT&T

  5. PASD Transmission Diagram Received by Antenna 1 Received by Antenna 2 Other Traffic Other Traffic Other Traffic 1 2 1 1 2 3 4 From AP From STA ACK ACK ACK NAK 1st Burst Unsuccessfully Decoded 1st + 2nd Burst Successfully Decoded 1st Burst Successfully Decoded 1st Burst Unsuccessfully Decoded 1st + 2nd Burst Unsuccessfully Decoded 1st Burst Unsuccessfully Decoded 1st + 2nd Burst Successfully Decoded R. R. Miller, AT&T

  6. PASD: Advantages • Only one receiver and antenna switch required • Lower power than conventional combining diversity/MIMO • Lower cost (memory is inexpensive compared to 2nd radio) • Simple implementation using known processing blocks • Extension of client autonomousswitched diversity • More reliable than antenna selection during preamble • Effective in changing RF environments (e.g. slow mobility) • Minimizes use of radio resource in good environments • Seamlessly maintains PER/minimizes repeats when environment degrades • Improves seamless VoIP, video, gaming experience. • Performance near MIMO • Can use Space-Time Coding (STC) R. R. Miller, AT&T

  7. PASD Architecture Analysis/Simulation Diagram R. R. Miller, AT&T

  8. PASD Performance: BER, PER R. R. Miller, AT&T

  9. PASD Performance: Transmissions R. R. Miller, AT&T

  10. PASD Architecture (MIMO) R T Single Stream Client AP Antenna 1 Burst 1 M1 DEMOD A/D MRC M2 R Antenna 2 MIMO PHY/MAC T ARQ Processor R Burst 2 T Simplified Implementation Diagram R. R. Miller, AT&T

  11. PASD Performance w.r.t. MIMO R. R. Miller, AT&T

  12. PASD Performance w.r.t. MIMO R. R. Miller, AT&T

  13. Recommendation Incorporate PASD support in the 802.11n draft to maximize goodput to low-cost, low power “single stream” handheld devices, especially those that provide real-time application value to mobile users, while preserving the radio resource. R. R. Miller, AT&T

  14. References “Analysis of a PASD Antenna System In Rayleigh Fading Channels”, D. Bai, S. S. Ghassemzadeh, R. R. Miller, V. Tarokh. R. R. Miller, AT&T

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