1. Submission doc.: IEEE802.11-11/0108r0 January 11 Slide 1 Evaluation of neighbors impact on channel allocation for dense environment and Video use cases Date: 2011-01-17 Authors: P. Chambelin & al.,(Technicolor))

2. Submission doc.: IEEE802.11-11/0108r0 Background (1/2) TGac agreed that inter-cell interference (ICI) in overlapping BSSs (OBSSs) environment is regarded as one of the main topics in coexistence ad-hoc group scope [1], [2]. The number of OBSSs will increase in the future. –TGac has already agreed to support 80 / 160MHz modes, which results in decrease the number of available channels [3], [4]. –The number of APs and STAs supporting 11ac function will increase. The objective of this study is to evaluate the impact of neighbors on potential issue for channel allocation in the dense environments cases, implying potential issue for video QoS and to propose orientations. January 2011 Slide 2 P. Chambelin & al.,(Technicolor))

3. Submission doc.: IEEE802.11-11/0108r0 Background (2/2) Channelization for Europe and Japan operation in 11ac Estimated maximum potential number of APs used within range [5] : – Detached Houses 12 – Terraced Houses 16 – Townhouses 25 – Single Layout Apartments 28 – Double Layer Apartments 53  40 Mhz Channel and larger BW are never applicable January 2011 Slide 3 P. Chambelin & al.,(Technicolor)) Bandwidth mode [MHz] 204080160 Number of channels19942

4. Submission doc.: IEEE802.11-11/0108r0 Study description and assumptions Buildings configuration –2 buildings (based on [6]) –5 floors / 125 flats (avg. 70.4m²) –Building size :  65x12m each. Separation : 12 to 22m January 2011 Slide 4 P. Chambelin & al.,(Technicolor))

5. Submission doc.: IEEE802.11-11/0108r0 Study description and assumptions Performed simulations –Single building with Tgn model –Single building with Ray Tracing –Two buildings with Ray Tracing January 2011 Slide 5 P. Chambelin & al.,(Technicolor)) Propagation data Indoor propagation loss formula (11n) *, F in MHz, d in feet For d<16.5ft : Lp = – 38 + 20 log F + 20 log d + Wall/Floor loss For d>16.5ft : Lp = – 38 + 20 log F + 20 log 16.5 + 35 log (d/16.5) + Wall/Floor Loss *Erceg et al (2004) as per 11n, Channel Model B – Residential 11nRT Interior drywallincluded in n.log(d)5dB Firewall10dB Exterior wall12dB15dB wall / 2dB glass Floor10dB

6. Submission doc.: IEEE802.11-11/0108r0 Attenuation comparisons (1/4) AP floor : TGn Model B vs RT (1 or 2 buildings) January 2011 Slide 6 P. Chambelin & al.,(Technicolor) back side AP front side AP

7. Submission doc.: IEEE802.11-11/0108r0 Attenuation comparisons (2/4) AP building : TGn Model B vs RT (1 building) January 2011 Slide 7 P. Chambelin & al.,(Technicolor)) –Good fitting between TGn and RT simulation, whatever the floor separation Receive signal above CCA levelReceive signal below CCA level CCA level limit For 23dBm AP front side AP

8. Submission doc.: IEEE802.11-11/0108r0 Attenuation comparisons (3/4) AP building : RT, influence of 2 nd building January 2011 Slide 8 P. Chambelin & al.,(Technicolor)) –Increased power due to reflections on second building but for low level Receive signal above CCA levelReceive signal below CCA level CCA level limit For 23dBm AP front side AP

9. Submission doc.: IEEE802.11-11/0108r0 Attenuation comparisons (4/4) AP building vs second building : RT January 2011 Slide 9 P. Chambelin & al.,(Technicolor)) –Up to 15dB more power in other building for front side AP Receive signal above CCA levelReceive signal below CCA level CCA level limit For 23dBm AP front side AP

10. Submission doc.: IEEE802.11-11/0108r0 Intermediate conclusions TGn model wasn’t design for multi-building simulation but provides good matching with RT simulations in single building. As interferers from other buildings can be more powerful, extended study is needed to cover multi-building cases Ray tracing allows to cover complex building/ environment cases and to compute accurate attenuations. Absolute results depends on the wall attenuation selected: –These parameters need to be fixed for the in the EM doc. January 2011 Slide 10 P. Chambelin & al.,(Technicolor))

11. Submission doc.: IEEE802.11-11/0108r0 Evaluation of the perturbations Assumptions : –AP at 1 st floor and at 3 rd floor –AP EIRP = 23 dBm or 3 dBm –Covered areas for CCA level (-82dBm) January 2011 Slide 11 P. Chambelin & al.,(Technicolor)) CCA level at AP level (1st floor)CCA level 3rd floors 23dBm AP3dBm AP

12. Submission doc.: IEEE802.11-11/0108r0 Conclusion on perturbations (1/2) Even if the distance between buildings is 20 m, the power level coming from building 1 in building 2 can be higher than in building 1. The CCA level is reached on an area equivalent to 14 flats in the AP’s building (23 dBm EIRP); up to 27 flats when considering also building 2. The reached CCA level area can be reduced for lower power AP : equivalent to 4 flats in the AP’s building for 3 dBm EIRP. Interference coming from the second building have to be considered January 2011 Slide 12 P. Chambelin & al.,(Technicolor))

13. Submission doc.: IEEE802.11-11/0108r0 Conclusion on perturbations (2/2) Covered area at CCA level (–82dBm) ⇔ Interfered surface January 2011 Slide 13 P. Chambelin & al.,(Technicolor)) 23dBm AP3dBm AP AP building1003m² avg. (1365 max)274m² avg. (322 max) Other building893m² avg. (1576 max)99m² avg. (203 max) Both building1896m² avg. (2941 max)373m² avg. (525 max) In average, a device interfere in other buildings as much as in its own building (sometimes more!)

14. Submission doc.: IEEE802.11-11/0108r0 Summary We evaluated the interference level in dense environment by considering also a neighbor building The impact of reflection by the second building is not negligible Ray tracing aims accurate results for complex multi-building cases ! By considering the 40/80 MHz mandatory channels of TGac, it would be challenging to make the channel allocation without channel sharing and thus to guaranty QoS for Video. The interest of power reduction has been shown and should be consider by the group. Smart TPC will bring high benefit, but need to be implement in the same way in all products to be efficient. Without these simple mechanisms, Video over TGac will be difficult, or will require more complex mechanism, meaning with overhead ! Next steps: –to consider other difficult environments –To work on channel allocation, power management for various service level January 2011 Slide 14 P. Chambelin & al.,(Technicolor))

15. Submission doc.: IEEE802.11-11/0108r0 References –[1] Rolf de Vegt et al., “Proposed Scope for Tgac Ad Hoc Groups,” Doc.: IEEE 802.11-09/1175r1. [2] T. Takatori et al., “OBSS issue in 802.11ac,” Doc.: IEEE 802.11- 09/0536r0. [3] L. Cariou et al., “Evaluation of the saturation of the 5GHz band,” Doc.: IEEE 802.11-10/0846r2. [4] R. Stacey et al., “Specification Framework for TGac,” Doc.: IEEE 802.11-09/0992r15. [5] G. Smith, “TGaa OBSS background,” Doc.: IEEE 802.11- 09/0762r0. [6] V. Guillet et al. “Frequency Assignement and Capacity of WLANs in the Home Environment”, Journées scientifiques « Propagation et Télédétection », Mar09 January 2011 Slide 15 P. Chambelin & al.,(Technicolor))

16. Submission doc.: IEEE802.11-11/0108r0 Straw Poll 1 Do you support the idea to continue studying the impact of interference and transmit power management within Tgac context, meaning with several independant and simultaneous clients ? January 2011 Slide 16 P. Chambelin & al.,(Technicolor))

17. Submission doc.: IEEE802.11-11/0108r0 Straw Poll 2 Will you consider modifications to draft standard to improve channel re-use in dense environments ? January 2011 Slide 17 P. Chambelin & al.,(Technicolor))