1. doc.: IEEE 802.11-02/594r0 Submission September 2002 M. Benveniste & D. Chen, Avaya Labs ResearchSlide 1 PF Differentiation and EDCF/RR Mathilde Benveniste benveniste@ieee.org Dongyan Chen Avaya Labs - Research

2. doc.: IEEE 802.11-02/594r0 Submission September 2002 M. Benveniste & D. Chen, Avaya Labs ResearchSlide 2 Our Objective Re-introduce persistence factors to help improve EDCF performance [01/409r2] RRs [QoS-Null frames] can have their own EDCF priority class with parameters: –AIFS = PIFS (with backoff >= 1) shared with other TCs –CWmin shorter than that of other TCs with same AIFS –PF smallest of all TCs

3. doc.: IEEE 802.11-02/594r0 Submission September 2002 M. Benveniste & D. Chen, Avaya Labs ResearchSlide 3 Simulation Results for PF Differentiation Related Reference: 02/525r0 Three loads considered on 11Mbps DS channel: Load1 is transmitted by polling with EDCF/RR - 8 stations engaged in two-way exchange with AP of time-sensitive bursty traffic Payload=120 bytes; inter-arrival fixed at 10 ms when ON; exponential 342 ms ON /650 ms OFF (example: silence suppressed voice) Load2 contends for the channel through EDCF – 6 stations sending high priority data uplink Payload=724 bytes; inter-arrival exponential at 8.2 ms Load3 contends for the channel through DCF – 5 stations sending low priority data uplink Payload=724 bytes; inter-arrival exponential at 8.2 ms

4. doc.: IEEE 802.11-02/594r0 Submission September 2002 M. Benveniste & D. Chen, Avaya Labs ResearchSlide 4 Simulation Scenarios The performance of EDCF/RR is compared under two scenarios that differ with respect to their PFs No PF differentiation (NPF) TC1 [for RRs] – AIFS=PIFS; CWmin=8; CWmax=8; (PF=1) TC2 [for Load 2] – AIFS=PIFS; Cwmin=16; CWmax=16; (PF=1) TC3 [for Load 3] – AIFS=DIFS; Cwmin=32; CWmax=1024; (PF=2) With PF differentiation (WPF) TC1 [for RRs] – AIFS=PIFS; CWmin=8; CWmax=2; PF=0.5 TC2 [for Load 2] – AIFS=PIFS; Cwmin=16; CWmax=1024; PF=1.5 TC3 [for Load 3] – AIFS=DIFS; Cwmin=32; CWmax=1024; PF=2 Uplink and downlink transmission through HCF in CP the two reservation mechanisms –CC/RR: CCI period=5 ms; CCOPS=50 –EDCF/RR: PF=0.5 [01/409r2]; AIFS=PIFS; Cwmin=8 is compared under two scenarios Under low load (LL) The load consists of time-critical bursty traffic (Load1, p 8) With heavy DCF load (HL) A best effort load of 5 Mpbs is added (Load2, p 8)

5. doc.: IEEE 802.11-02/594r0 Submission September 2002 M. Benveniste & D. Chen, Avaya Labs ResearchSlide 5 Load1 uplink end-to-end delay (sec) NPF without PF differentiation WPF with PF differentiation PF differentiation helps RR & uplink transmission EDCF/RR becomes more effective Without optimization

6. doc.: IEEE 802.11-02/594r0 Submission September 2002 M. Benveniste & D. Chen, Avaya Labs ResearchSlide 6 Load1 downlink end-to-end delay (sec) NPF without PF differentiation WPF with PF differentiation PF differentiation reduces contention It helps HCF channel access for downlink transmission

7. doc.: IEEE 802.11-02/594r0 Submission September 2002 M. Benveniste & D. Chen, Avaya Labs ResearchSlide 7 Load2 end-to-end delay (sec) NPF without PF differentiation WPF with PF differentiation PF differentiation reduces collisions between TC1 and TC2 It reduces delays for both TCs

8. doc.: IEEE 802.11-02/594r0 Submission September 2002 M. Benveniste & D. Chen, Avaya Labs ResearchSlide 8 Load3 end-to-end delay (sec) Without PF differentiation, low-priority traffic gets through sooner, while TC1 and TC2 transmissions collide WPF with PF differentiation NPF without PF differentiation

9. doc.: IEEE 802.11-02/594r0 Submission September 2002 M. Benveniste & D. Chen, Avaya Labs ResearchSlide 9 Conclusions PF differentiation helps EDCF/RR get the RRs out sooner and thus improves HCF performance PF differentiation reduces contention among EDCF TCs and improves EDCF performance PFs are simple to implement [01/409r2]