January 2001

Don Shaver, et.al. Texas InstrumentsSlide 1

doc.: IEEE 802.11-01/036

Submission

Enhanced Contention Period Proposal for QoS and Throughput

Enhancements -Objectives and Introduction

Donald P. Shaver, Jin-Meng Ho, Sid Schrum, Khaled Turkiand Matthew B. ShoemakeTexas Instruments Incorporated

12500 TI Blvd.Dallas, Texas 75243

(214) 480-4349 (Shaver), (214) 480-1994 (Ho), (919) 463-1043 (Schrum), (214) 480-6908 (Turki)

(214) 480-2344 (Shoemake)shaver@ti.com, jinmengho@ti.com, sschrum@ti.com,

khaled@ti.com, shoemake@ti.com

January 2001

Don Shaver, et.al. Texas InstrumentsSlide 2

doc.: IEEE 802.11-01/036

Submission

Objectives• Conform to the QoS Baseline Proposal [1]

• Unambiguously define a robust, optimized hybrid access method for use in the contention period [2]

• Specify a hybrid coordination function to facilitate the reduction in conformance levels [3], [4], [5]

• Analyze, model, and simulate the proposed method to minimize risk and gain confidence in the proposed solution [6]

• Compare benefits and advantages with respect to other leading EDCF proposals [3], [6], [7]

January 2001

Don Shaver, et.al. Texas InstrumentsSlide 3

doc.: IEEE 802.11-01/036

Submission

Texas Instruments Proposal• Introduces contention-free access mechanisms and

contention-free transfer rules into the CP• Enhances contention access in the CP by adaptively

adjusting permission probabilities with channel load changes (p-DCF)

• Shows p-DCF may be implemented via probability or backoff• Unifies contention-free and contention access in the CP

Simulation Results• Demonstrates improved EDCF performance and robustness

are achieved using p-DCF access mechanism

Introduction

January 2001

Don Shaver, et.al. Texas InstrumentsSlide 4

doc.: IEEE 802.11-01/036

Submission

Aggregate data arrival rate = 6 Mbps

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0 5 10 15 20 25 30 35 40 45 50

Simulation Time (sec)

Del

ay (m

s)

p-DCF: idle time ~ collision timep-DCF: PP offset by +/- 15%Legacy: CO =0, CWmin = 31v-DCF: CO = 10, CWmin = 15v-DCF: CO = 10, CWmin = 63

Contention-Based Access:Simulation Result

Operation “recovered” from congestion as frames exceeding retry counts were discarded

Smaller CWmin (higher priority) produced longer delays

January 2001

Don Shaver, et.al. Texas InstrumentsSlide 5

doc.: IEEE 802.11-01/036

Submission

References

[1] QoS Baseline Proposal - revision 1, IEEE 802.11-00/360r1

[2] Hybrid Channel Access for DCF QoS and Throughput Enhancements, IEEE 802.11-00/468

[3] Contention-Free and Contention-Based Access in Contention Period, IEEE 802.11-00/467r1

[4] An Integrated 802.11 QoS Model with Point-Controlled Contention Arbitration, IEEE 802.11-00/448

[5] A Hybrid Coordination Function for QoS, IEEE 802.11-00/452

[6] Simulation Results for p-DCF, v-DCF and Legacy, IEEE 802.1-01/xxx

[7] p-DCF Proposal Summary, IEEE 802.11-00/xxx