OBSS Preamble Detection May 2013 March 2015 OBSS Preamble Detection Date: 2015-02-26 Authors: Osama Aboul-Magd (Huawei Technologies)

March 2015 Context In 11-14-1420-01 it was shown that errors on OBSS preambles were very high Scenario 1 with 3 channels Errors around 80-90% In this presentation we check the probability of preamble detection in both scneario 1 and scenario 2 Qualcomm

Simulation Setup: Scneario 1 March 2015 Simulation Setup: Scneario 1 3 channels Chosen to maximize distance between two apartments one 1 channel. 5 STAs per AP 1 antenna per AP & STA Qualcomm

Simulation Parameters March 2015 Simulation Parameters Simulator Type MAC simulator Tx Power (AP/STA) 20/15dBm Antenna Gain (AP/STA) 0/-2 dBi Traffic Model UL full buffer BSS Bandwidth 80MHz Noise Figure Noise Floor -101dBm per 20MHz Rate Control Algorithm single MCS chosen per link to maximize goodput MSDU size (bytes) 1476 TXOP size 4 ms Max Retx 10 Simulation Time (sec) PER Curve AWGN Qualcomm

Throughput results March 2015 Preamble Detection ON for all packets Premable Detection ON only for in-BSS packets CCA 5% 50% 90% Mean -52 0.32 17.46 63.51 26.28 -62 0.83 25.38 63.95 29.89 -72 2.17 28.18 56.03 30.36 -82 24.55 70.19 32.24 -92 0.77 20.58 61.56 27 CCA 5% 50% 90% Mean -52 0.40 18.88 71.15 29.41 -62 0.32 26.00 70.30 31.87 -72 1.89 31.66 60.97 32.72 -82 0.89 28.63 81.53 35.83 -92 1.05 21.98 67.90 30.10 Shape of curves remains the same regardless of whether Preamble Detection is ON or OFF for OBSS packets Note:having premable detection “OFF” for OBSS packets is like “OBSS color scheme” Qualcomm

Preamble Detection Results March 2015 Preamble Detection Results Median number of OBSS packets detected per second is 5 Equivalent to 20ms deferral out of 1000ms (Txop=4ms) 2% of the time spent deferring due to OBSS premables. Qualcomm

Preamble Detection Results cont. March 2015 Preamble Detection Results cont. % of successfully decoded OBSS preambles by all STAs in a BSS Total successfully decoded preambles in BSS/Total attempted decodes of preambles in BSS A device has an “attempted decode” of a preamble if the preamble is > -82 RSSI, and the device locks on to the preamble and tries to decode it.  roughly 10% decode rate for OBSS premabels Qualcomm

Simulation Setup: Scenario 2 March 2015 Simulation Setup: Scenario 2 “one room” 1 2 4 3 5 6 8 7 9 10 12 11 13 14 16 15 17 18 20 19 21 22 24 23 25 26 28 27 29 30 32 31 4 channels 5 STAs per AP 1 antenna per AP & STA Qualcomm

Simulation Parameters March 2015 Simulation Parameters Simulator Type MAC simulator Tx Power (AP/STA) 20/15dBm Antenna Gain (AP/STA) 0/-2 dBi Traffic Model UL full buffer BSS Bandwidth 80MHz Noise Figure Noise Floor -101dBm per 20MHz Rate Control Algorithm single MCS chosen per link to maximize goodput MSDU size (bytes) 1476 TXOP size 4 ms Max Retx 10 Simulation Time (sec) PER Curve AWGN Qualcomm

Throughput results March 2015 Whether premable detection is on for OBSS packets or not, shape of curve is similar. The ED level is the main factor affecting the shape of the tput curves If OBSS preambles were detected, the dotted black line should match the purple curve Qualcomm

Preamble Detection Results cont. March 2015 Preamble Detection Results cont. % of successfully decoded OBSS preambles by all STAs in a BSS Total successfully decoded preambles in BSS/Total attempted decodes of preambles in BSS A device has an “attempted decode” of a preamble if the preamble is > -82 RSSI, and the device locks on to the preamble and tries to decode it.  roughly 10% decode rate for OBSS premabels Qualcomm

March 2015 Conclusions For the simulation run in scenario 1 and scneario 2, OBSS preambles are not decoded very often. Around 10% of attempted decodes of OBSS preambles are successful This corroborates the results found in 11-14-1420-01 Could impact protocols that rely on preamble detection Qualcomm

Appendix Scenario 1, reuse 1, 1DL March 2015 Same parameters as sceneario 1, reuse 3 Turning Preamble Detection ON for OBSS packets doesn’t change the shape of the tput curve. ED No PD ED No PD ED No PD ED No PD ED No PD ED PD ON Qualcomm