1. doc.:IEEE 802.11-09/0536r0 Submission May 11th, 2009 Slide 1 OBSS issue in 802.11ac Authors: Date: 2009-05-11

2. doc.:IEEE 802.11-09/0536r0 Submission May 11th, 2009 Slide 2 Introduction More than 1 GBps throughput with multiple STAs and more than 500Mbps throughput for each STA are required in 11ac. Following new technologies are likely to be used –Higher order MIMO (> 4x4) –Spatial Division Multiple Access (SDMA) with more than 4 AP antennas –Larger Bandwidth (80 MHz mode) –Multi frequency channel Use multiple 20 MHz channels across multiple users. Increase in the number of APs / STAs is expected.

3. doc.:IEEE 802.11-09/0536r0 Submission May 11th, 2009 Slide 3 Background Giga-bit wired network is proliferating. Giga-bit wireless access is very attractive for both the very high data rate services such as IP-TV. Efficient aggregation function is attractive for low data rate services also such as VoIP services. 0.1 1 10 100 1000 10000 19751985199520052015 Year Throughput (Mbps) Ethernet 1Base-T 10Base-T 100Base-T 1000Base-T 10GBase-T USB WPAN USB1.0 USB1.1 USB2.0 USB3.0 802.11 802.11b 802.11a 802.11n 802.11ac WLAN 11ac is expected to cover from low data rate services to very high data rate services. Further increase in the throughput might be expected.

4. doc.:IEEE 802.11-09/0536r0 Submission May 11th, 2009 Slide 4 Proliferation of WLANs AP 802.11ac AP Large increase in the number of APs / STAs is expected.

5. doc.:IEEE 802.11-09/0536r0 Submission May 11th, 2009 Slide 5 5 80MHz mode Over size MIMO SDMA/OFDMA Others Number of available channels in 5GHz band 20MHz mode 40MHz mode 80MHz mode Frequency band allocation in Japan Only 4 channels can be used for 80MHz mode while 9 / 19 channels are available for 40 / 20 MHz mode.

6. doc.:IEEE 802.11-09/0536r0 Submission May 11th, 2009 Slide 6 OBSS in 802.11ac OBSS scenario is more likely to happen in 11ac compared to 11n due to limited. We think addressing OBSS issue in TGac is important because it highly relates to the spatial domain control. Example: Excessive NAV setting might affect throughput in the adjacent BSS. AP1 STA11 AP2 STA21STA22 Overlapped BSS BSS1BSS2 IEEE802.11acIEEE802.11a/n/ac

7. doc.:IEEE 802.11-09/0536r0 Submission May 11th, 2009 Slide 7 Possible Simulation Scenario Example of Evaluation Conditions –Number of APs = 2 Case 0: AP1:11n, AP2:11n Case 1: AP1:11ac, AP2: 11n Case 2: AP1: 11ac, AP2: 11ac –Location of APs: T.B.D. –Location of STAs: T.B.D. –Traffic from AP to STAs: T.B.D. –Traffic from STAs to AP: T.B.D. –Channel model type applied : T.B.D. Possible Requirements –Case 1 and Case2: Throughput at each AP must be equal to or higher than that of case 0. We think OBSS situation should be included in “Functional Requirements and Evaluation Methodology. ” AP1 STA11 AP2 STA21STA22 Overlapped BSS BSS1BSS2 IEEE802.11acIEEE802.11a/n/ac

8. doc.:IEEE 802.11-09/0536r0 Submission May 11th, 2009 Slide 8 Conclusions Large number of APs / STAs is expected in 802.11ac. OBSS is more likely to happen in 802.11ac compared to 802.11n. We propose addressing for OBSS issue in TGac. We also suggest the following functional requirement. “802.11ac shall maintain or increase throughput of each BSS in OBSS when some of 802.11a/n BSSs are replaced by 802.11ac BSSs.”