1. doc.: IEEE 802.11-09/1263r2 Submission Dec 2009 Z. Chen, C. Zhu et al [Preliminary Simulation Results on Power Saving] Date: 2009-12-17 Authors: Slide 1

2. doc.: IEEE 802.11-09/1263r2 Submission Dec 2009 Z. Chen, C. Zhu et al Abstract This presentation reports the preliminary results of our simulations of existing power saving mechanisms. –The scenario simulated is taken from IEEE 802 Doc 09/0161r02, Usage Model 2d: Wireless Networking for Office. –The performance and effects of APSD and PSMP have been examined. Slide 2

3. doc.: IEEE 802.11-09/1263r2 Submission Dec 2009 Z. Chen, C. Zhu et al Simulation Scenario* Traffic Conditions (per AP): 2 WLAN video streams 2 WVoIP streams Up to 5 best effort data streams The best effort data traffic can take up to 20% of the available bandwidth with saturated offered load. Use Case: 1.Users run different applications during the day and may start each application at different time. 2.A typical sequence is starting up a voice call, adding video sending/receiving multi- media data and discussing this over the voice/video link 3.The duration of such a use case is typically one hour. 4.Up to three of these “sessions” per AP may be going on in parallel. Pre-Conditions: Office with people engaged in high quality/high revenue services that involve video and voice interaction with client and transferring large volumes of multimedia data. A single AP serves 5 people. The office comprises 5 – 500 people. Application: Multiple applications run at the same time. High definition compressed video uses something like an Blu-ray codec. Voice is standard definition quality using a codec like G729. Aggregate bandwidth requirement is 5 simultaneous video streams per AP. Voice requirements are: ~50Kbps, Jitter <30msec. Delay <30msec. 1.0E-1 PER. Environment: Mostly not Line of sight within a single office. People walking around the office. There is potentially unmanageable interference from neighboring offices within 100 feet (horizontally) or adjacent floors (vertically) when in 2.4 / 5 GHz. AP density is more than 1 AP per 40m X 40m * This was taken from Doc 09/0161r02, Usage Model 2d: Wireless Networking for Office Slide 3

4. doc.: IEEE 802.11-09/1263r2 Submission Dec 2009 Z. Chen, C. Zhu et al Network Topology Slide 4

5. doc.: IEEE 802.11-09/1263r2 Submission Dec 2009 Z. Chen, C. Zhu et al Traffic Pattern Flow No. STAs (Source/Sink) Source Location (meters) Sink Location (meters) Channel Model Application (Forward Traffic / Backward Traffic) Application Load (Mbps) (Forward / Backward) Rate Distribution (Forward / Backward) MSDU Size (B) (Forward / Backward) Max. Delay (ms) (Forward / Backward) Max. PLR (Forward / Backward) 1AP / STA1(0,0)(0,5)CVoIP / VoIP0.008 / 0.008UDP / UDP20/ 2030 / 305% / 5% 2AP / STA2(0,0)(-10,-10)CVoIP / VoIP0.008 / 0.008UDP / UDP20/ 2030 / 305% / 5% 3AP/ STA3(0,0)(5,0)CVoIP / VoIP0.008 / 0.008UDP / UDP20/ 2030 / 305% / 5% 4STA3/ AP(5,0)(0,0)C Local file transferMax. 1GbpsTCP300INFN/A 5AP/ STA 4(0,0)(-7,7)CVoIP / VoIP0.008 / 0.008UDP / UDP20/ 2030 / 305% / 5% 6STA 4/ AP(-7,7)(0,0)C Blu-ray/ control channel50.00 / 0.06 Constant, UDP / Constant UDP1500 / 6420 / 100 10^-7 / 10^-2 7STA 5/ AP(10,5)(0,0)C Local file transferMax. 1GbpsTCP300INFN/A 8STA 5/ AP(10,5)(0,0)C Blu-ray/ control channel50.00 / 0.06 Constant, UDP / Constant UDP1500 / 6420 / 100 10^-7 / 10^-2 Slide 5

6. doc.: IEEE 802.11-09/1263r2 Submission Dec 2009 Z. Chen, C. Zhu et al Simulation Parameters Bit rate for DATA packets500 Mbps Bit rate for RTS/CTS/ACK6 Mbps aCWmin31 aCWmax1024 PLCPDataRate6 Mbps A Slot Time9 us SIFS16 us DIFS34 us PreambleLength144 bits PLCPHeaderLength48 bits MAC header224 bits IP header160 bits DATA packet Payload size + MAC header + IP header=Payload size+ 384 bits RTS160 bits CTS, ACK112 bits AC 3 for VoIP trafficPF 2, AIFS 2, CW_MIN 7, CW_MAX 15 AC 2 for Video trafficPF 2, AIFS 2, CW_MIN 15, CW_MAX 31 AC 0 for Video Best effort trafficPF 2, AIFS 7, CW_MIN 31, CW_MAX 1023 Slide 6 The simulation runs on ns2 platform.

7. doc.: IEEE 802.11-09/1263r2 Submission Dec 2009 Z. Chen, C. Zhu et al Performance without Aggregation Network Performance with APSD Delay (ms)Throughput (Kbps)Packet Loss (%) UplinkDownlinkUplinkDownlinkUplinkDownlink VoIP0.36110.6228800 Video326.8130.66119,2986060.230 TCP18.668N/A998.198N/A00 Network Performance without APSD Delay (ms)Throughput (Kbps)Packet Loss (%) UplinkDownlinkUplinkDownlinkUplinkDownlink VoIP0.3750.3518800 Video304.9890.61919,9076059.060 TCP22.137N/A1,068.31N/A00 Note the data here are average numbers over 4 VoIP sessions, 2 Video sessions and 2 TCP sessions. Slide 7

8. doc.: IEEE 802.11-09/1263r2 Submission Dec 2009 Z. Chen, C. Zhu et al 802.11n Capacity with Video traffic 1. Video Frame = (Data + IP header + MAC header)/DataRate ( 1500 + 20 + 28 ) * 8 / 500 = 24.768 µs 2. Require Bandwidth = Application Load * Frame Start Interval / Video Frame 50 * (34+67+28+24.768+16+32) / 24 = 420.315 Mbps 3. Number of Video uplink sessions = Bandwidth * Utilization / Require Bandwidth 500 * 0.8 / 420.315 = 1.05 Time DIFS Contention Window PLCP Header Video Frame SIFS Ack 34 µs67 µs (min average) 28 µs16 µs 32 µs Reference: IEEE 802.11-07/2704r00, Efficiency of VoIP on 802.11n Slide 8

9. doc.: IEEE 802.11-09/1263r2 Submission Dec 2009 Z. Chen, C. Zhu et al Data Aggregation In order to support the given traffic load, Aggregated MSDU is used. –In the results after this slide, four video MSDUs are aggregated into one A-MSDU. –VoIP and TCP packets are not aggregated in APSD. –VoIP, TCP, video packets are aggregated in PSMP Slide 9

10. doc.: IEEE 802.11-09/1263r2 Submission Dec 2009 Z. Chen, C. Zhu et al APSD Power Saving Effect Slide 10 STA 1 (VoIP only) STA 2 (VoIP only) STA 3 (VoIP, TCP) STA 4 (VoIP, Video) STA 5 (VoIP, Video)

11. doc.: IEEE 802.11-09/1263r2 Submission Dec 2009 Z. Chen, C. Zhu et al PSMP Power Saving Effect Slide 11 STA 1 (VoIP only) STA 2 (VoIP only) STA 3 (VoIP, TCP) STA 4 (VoIP, Video) STA 5 (VoIP, Video)

12. doc.: IEEE 802.11-09/1263r2 Submission Dec 2009 Z. Chen, C. Zhu et al VoIP Traffic Delay with APSD, PSMP and w/o Power Saving STA 1 (VoIP only) STA 2 (VoIP only) STA 3 (VoIP, TCP) STA 4 (VoIP, Video) Note: Jitter for VoIP traffic with APSD is < 2 µs, with PSMP is < 0.1 µs, and <0.1 µs without Power saving Slide 12

13. doc.: IEEE 802.11-09/1263r2 Submission Dec 2009 Z. Chen, C. Zhu et al Video Traffic Performance Uplink w/ APSD Downlink w/ APSD Uplink w/o PS Downlink w/o PS Uplink w/ PSMP Downlink w/ PSMP Slide 13

14. doc.: IEEE 802.11-09/1263r2 Submission Dec 2009 Z. Chen, C. Zhu et al APSD and PSMP’s effect on TCP throughput STA3 (VoIP, TCP) STA5 (Video, TCP) Slide 14 Note: all TCP traffic is uplink traffic

15. doc.: IEEE 802.11-09/1263r2 Submission Dec 2009 Z. Chen, C. Zhu et al Delay Comparison for all Traffic Types VoIPVideoTCP Note: 1) the data here are average numbers over 4 VoIP sessions, 2 Video sessions and 2 TCP sessions. 2) there is no data collected for downlink TCP traffic so the data is not available. Slide 15

16. doc.: IEEE 802.11-09/1263r2 Submission Dec 2009 Z. Chen, C. Zhu et al Summary and Future Works Summary –A single stream of 500Mbps cannot support the given traffic load without aggregation. –APSD allows STAs sleep >95% of the time for VoIP traffic in this specific scenario; –PSMP allows STAs sleep >85% of the time for VoIP only traffic and >70% of the time for Video traffic. –APSD increases the delay for downlink VoIP traffic (from <1ms to ~10ms), but still within the requirement (<30ms). –APSD slightly increases the delay for video traffic when it is running in the AP. –TCP delay is >20% larger, and throughput is about 10% lower when APSD is running. –TCP throughput of STA 5 is higher since the video packet is big and TCP packets are aggregated in PSMP. Future work –Develop module to support direct links so that STA to STA traffic can be simulated. –Support multiple streams (receivers) Enhanced MAC functions needed. –Perform simulations on other 11ac scenarios. Slide 16