1. doc.: IEEE 11-13/1113r0 Submission Sept. 2013 Minho Cheong (ETRI)Slide 1 Channel Modeling for Dense Wi-Fi Environments Date: 2013-09-17 Authors: NameAffiliationsAddressPhoneemail Minho CheongETRI161 Gajeong-dong, Yuseong-Gu, Daejoen, Korea +82 42 860 5635minho@etri.re.kr Jae Seung LeeETRI161 Gajeong-dong, Yuseong-Gu, Daejoen, Korea +82 42 860 1326jasonlee@etri.re.kr Hyoung Jin KwonETRI161 Gajeong-dong, Yuseong-Gu, Daejoen, Korea +82 42 860 1698kwonjin@etri.re.kr Sok-Kyu LeeETRI161 Gajeong-dong, Yuseong-Gu, Daejoen, Korea +82 42 860 5919sk-lee@etri.re.kr

2. doc.: IEEE 11-13/1113r0 Submission Abstract This presentation gives set of issues in channel modeling for dense Wi-Fi environments. Sept. 2013 Slide 2Minho Cheong (ETRI)

3. doc.: IEEE 11-13/1113r0 Submission Channel Modeling in HEW [4] Initial version of both indoor and outdoor channel model considered –Indoor channel models TGn (IEEE 802.11-03/940r4) and TGac (IEEE 802.11-09/0308r12) channel model documents provided SISO, MIMO and MU-MIMO channels models. Principle: take advantage of well-established TGn and TGac channel models –Outdoor channel model Three outdoor channel model proposals have been proposed in HEW (summary in following slides) Current principle: adopt outdoor channel model from other organizations instead of developing outdoor channel model based on measurements from IEEE 802.11 working group. General structure seems good. But, not fully reflects some specific environments for HEW –e.g., super-dense environment Sept. 2013 Slide 3Minho Cheong (ETRI)

4. doc.: IEEE 11-13/1113r0 Submission Need of Supplements to Current Model High density of STAs –such as usage model 4a “Super-dense Urban Street - public access and cellular offload” Sept. 2013 Slide 4Minho Cheong (ETRI) Street Supporting in Word Cup 2002 PSY’s Performance Outdoor Man. United’s Street Parade

5. doc.: IEEE 11-13/1113r0 Submission Need of Supplements to Current Model High density of STAs [5] –All the usage models (only except category 5) may be very dense –With density of users up to 1.0 user/m 2 Sept. 2013 Slide 5Minho Cheong (ETRI)

6. doc.: IEEE 11-13/1113r0 Submission Need of Supplements to Current Model High density scenarios [6] –1a-Stadium: High density of users (0.5users/m²), inter-AP distance between 12 and 20 meters. –1b-Airport/trains: Each AP serves 120 users in a 200m 2 area (0.6 users/m²). The inter-AP distance is in the range of 15~20m. Single/multiple operators. –1c- Exhibition halls: Each AP serves 100 users in a 100m 2 (1.0 user/ m²) area. The inter-AP distance is in the range of 5~10m. –1d- Shopping malls: High density of users and high density of APs (undefined user/ m², but similar to “1c-Exhibition hall”) –1e-Education: Dense STAs (40~60 STAs) in one classroom with one AP. Class room size is ~ 300 m² (0.2 user/ m²). Sept. 2013 Slide 6Minho Cheong (ETRI)

7. doc.: IEEE 11-13/1113r0 Submission Need of Supplements to Current Model High density scenarios [6] –2a-Wireless office: Typical distances between STAs and AP in the room are < 50m. 20-30 STAs per AP. Max. user/ m² =30/(3.14*50^2)= 0.04 user/ m² –3a-Dense apartment building: Building with 100 apartments. One AP in each apartment of 10mx10m randomly positioned. 5 STA per AP randomly positioned in the apartment. Max. user/ m² = 0.01 user/ m² –4a-Super-dense urban street: The inter-AP distance is in the range of 20-50m. STA distribution density is about 0.5 user/ m 2. In specific city squares, public events gather even higher densities 1.0 user/m² and inter-AP distance is in the range of 10-20m. Sept. 2013 Slide 7Minho Cheong (ETRI)

8. doc.: IEEE 11-13/1113r0 Submission Need of Supplements to Current Model There need additional considerations to reflect high density of STAs in the HEW –which the HEW SG has regarded as very important starting point such as –(1) Additional path-loss due to human body blockage –(2) Adjustment of indoor scattering parameters –(3) Adjustment of indoor LOS/NLOS breakpoints because –many people very close near by induce quite more ray-scatterings and non-negligibly frequent blockage by human bodies Sept. 2013 Slide 8Minho Cheong (ETRI)

9. doc.: IEEE 11-13/1113r0 Submission Additional Path-loss due to Human Body Blockage In super-dense scenarios, in addition to general indoor (from 802.11n/ac channel model) or outdoor (from WINNER or ITU model), we need to consider the following environments as well Sept. 2013 Slide 9Minho Cheong (ETRI) AP My STA (smart phone)

10. doc.: IEEE 11-13/1113r0 Submission Additional Path-loss due to Human Body Blockage Blockage effect due to head-to-hand (purple in slide 9) –Whenever a person watches his smart-phone in super-dense environments, his own head is likely to block the link to AP many times, which has been a problem even in nowadays Blockage effect due to other people (red in slide 9) –In most of HEW usage models, many people are very crowded within a limited area with super high density more than 0.5 person/m 2 or 1.0 person/m 2. –In these environments, we can hardly expect an LOS link between AP and STA due to blockage effect from other human bodies, which seems to require additional path loss Sept. 2013 Slide 10Minho Cheong (ETRI)

11. doc.: IEEE 11-13/1113r0 Submission Additional Path-loss due to Human Body Blockage Human body blockage modeled in other standards –IEEE 802.11ad channel modeling using 60GHz band [7] Sept. 2013 Slide 11Minho Cheong (ETRI)

12. doc.: IEEE 11-13/1113r0 Submission Additional Path-loss due to Human Body Blockage Human body blockage modeled in other standards –IEEE 802.11ad channel modeling using 60GHz band [7] Because 60GHz band ray have quite a directivity –There is lots of power gap between main path and remaining paths –Penetration loss due to human body is only about 20dB Sept. 2013 Slide 12Minho Cheong (ETRI)

13. doc.: IEEE 11-13/1113r0 Submission Additional Path-loss due to Human Body Blockage Human body blockage modeled in other standards –IEEE 802.15.6 (Body Area Network) channel modeling [8] Using 13.5MHz band, 5-50MHz band Using 400MHz band, 600MHz band, 900MHz band Using 2.4GHz band Using 3.1-10.6GHz band Sept. 2013 Slide 13Minho Cheong (ETRI)

14. doc.: IEEE 11-13/1113r0 Submission Additional Path-loss due to Human Body Blockage Human body blockage modeled in other standards –IEEE 802.15.6 (Body Area Network) channel modeling [8] –e.g.) Type C model at 2.36GHz Sept. 2013 Slide 14Minho Cheong (ETRI)

15. doc.: IEEE 11-13/1113r0 Submission Additional Path-loss due to Human Body Blockage Human body blockage modeled in other standards –IEEE 802.15.6 (Body Area Network) channel modeling [8] –e.g.) Type C.1 model at 3.1-5.1GHz Sept. 2013 Slide 15Minho Cheong (ETRI)

16. doc.: IEEE 11-13/1113r0 Submission Additional Path-loss due to Human Body Blockage Human body blockage modeled in other standards –IEEE 802.11ad channel modeling using 60GHz band [7] Because 2.4GHz & 3.1-5.1 GHz band ray have less directivity (maybe very similar to WLAN band) –There isn’t much power gap between 1 st path and remaining paths –Penetration loss due to human body is over 60dB Sept. 2013 Slide 16Minho Cheong (ETRI)

17. doc.: IEEE 11-13/1113r0 Submission Additional Path-loss due to Human Body Blockage Lessons from observation of other channel models –Because IEEE802.15.6 results must be very similar to Wi-Fi bands –We can regard any Wi-Fi ray touched by human body as almost disappeared in super-dense scenario So, whenever there comes disappearance of major paths (main path or other non-negligible paths) due to human body blockage, it will definitely increase a lot its path loss overall Sept. 2013 Slide 17Minho Cheong (ETRI)

18. doc.: IEEE 11-13/1113r0 Submission Additional Path-loss due to Human Body Blockage Possible Supplements –Path loss = Path loss (current model) + delta –Add an additive (delta) due to human blockage to the current indoor & outdoor channel model specifically in super-dense environments Work to do in the future –Need to measure & investigate the statistics of increased path loss due to human body blockage in Wi-Fi super-dense environments According to indoor or outdoor According to density of STAs According to location of AP (3 dimensional) Sept. 2013 Slide 18Minho Cheong (ETRI)

19. doc.: IEEE 11-13/1113r0 Submission Adjustment of Indoor Scattering Parameters IEEE 802.11n Channel Model [9] –IEEE802.11n channel models (MIMO) (by Vinko et. al) [9] based on the cluster model developed by Saleh and Valenzuela [10], and further elaborated upon by Spencer et al. [11], Cramer et al. [12], and Poon and Ho [13]. –IEEE802.11ac channel models (SU/MU-MIMO) [14] additionally applied AoD/AoA randomization and BW widening based on 802.11n channel Cluster model assumes –Some limited number of clusters in it –With angular spread statistics –With delay spread statistics Sept. 2013 Slide 19Minho Cheong (ETRI)

20. doc.: IEEE 11-13/1113r0 Submission Adjustment of Indoor Scattering Parameters Sept. 2013 Slide 20Minho Cheong (ETRI)

21. doc.: IEEE 11-13/1113r0 Submission Adjustment of Indoor Scattering Parameters Sept. 2013 Slide 21Minho Cheong (ETRI)

22. doc.: IEEE 11-13/1113r0 Submission Adjustment of Indoor Scattering Parameters There may be need to modify the cluster parameters for newly-introduced super-dense environments –Because number of clusters increased (Model B/C/D may not fit) –Linear regression analysis between “mean delay spread” and “mean angular spread” may not exactly fit for super-dense scenarios Sept. 2013 Slide 22Minho Cheong (ETRI)

23. doc.: IEEE 11-13/1113r0 Submission Adjustment of Indoor Scattering Parameters Possible Supplements –Need to check whether relation in the current modeling equation between “mean angular spread” and “mean delay spread” can be still applicable to super-dense environments –Need to newly measure delay spread and angular spread statistically in super-dense environments –But, it may require huge work to do… Sept. 2013 Slide 23Minho Cheong (ETRI)

24. doc.: IEEE 11-13/1113r0 Submission Adjustment of Indoor LOS/NLOS Breakpoints IEEE802.11n/802.11ac channel model assumed –Within some distance (breakpoint): regarded as LOS channel –Over some distance (breakpoint): regarded as NLOS channel Sept. 2013 Slide 24Minho Cheong (ETRI)

25. doc.: IEEE 11-13/1113r0 Submission Adjustment of Indoor LOS/NLOS Breakpoints Breakpoints needs to be quite smaller in super-dense –Because HEW SG assumes that super-dense scenario may have density of STAs of 0.5 users/m 2 or 1.0 users/m 2 or more –Current breakpoint values (5m, 10m, 20m and 30m) seems too large when we consider high density STAs indoor scenarios Possible Supplements –Add one more option of “LOS/NLOS breakpoint” d BP smaller than 5m for super-dense environments –(if possible) add one more option of “shadow fading std. dev. after d BP ” larger than 6dB for super-dense environments Sept. 2013 Slide 25Minho Cheong (ETRI)

26. doc.: IEEE 11-13/1113r0 Submission Suggestion Additional path-loss due to human body blockage –Add an additive path loss to the current path loss model for indoor and outdoor channel model as well See slide 18 Adjustment of indoor scattering parameters –Need to investigate, but it requires huge work to do… for indoor channel model only See slide 23 Adjustment of indoor LOS/NLOS breakpoints –Add one more mode for super-dense environments for indoor channel model only See slide 25 Sept. 2013 Slide 26Minho Cheong (ETRI)

27. doc.: IEEE 11-13/1113r0 Submission Slide 27 References [1] 11-03-0802-23-000n-usage-models [2] 11-13-0840-01-0hew-HEW-functional-requirements-follow-up [3] 11-13-0837-00-0hew-Considerations-on-HEW-evaluation- methodology [4] 11-13-1135-02-0hew-summary-on-hew-channel-models [5] 11-13-0657-06-0hew-hew-sg-usage-models-and-requirements- liaison-with-wfa [6] 11-13-0787-00-0hew-followup-on-functional-requirements [7] 11-09-0334-08-00ad-channel-models-for-60-ghz-wlan-systems [8] 15-08-0780-09-0006-Channel Model for Body Area Network (BAN) Minho Cheong (ETRI) Sept. 2013

28. doc.: IEEE 11-13/1113r0 Submission References [9] 11-03-0940-04-000n-tgn-channel-models [10] 11-09-0308-12-00ac-tgac-channel-model-addendum-document [11] A.A.M. Saleh and R.A. Valenzuela, “A statistical model for indoor multipath propagation,” IEEE J. Select. Areas Commun., vol. 5, 1987, pp. 128-137. [12] Q.H. Spencer, et al., “Modeling the statistical time and angle of arrival characteristics of an indoor environment,” IEEE J. Select. Areas Commun., vol. 18, no. 3, March 2000, pp. 347-360. [13] R.J-M. Cramer, R.A. Scholtz, and M.Z. Win, “Evaluation of an ultra-wide-band propagation channel,” IEEE Trans. Antennas Propagat., vol. 50, no.5, May 2002, pp. 561-570. [14] A.S.Y. Poon and M. Ho, “Indoor multiple-antenna channel characterization from 2 to 8 GHz,” submitted to ICC 2003 Conference. Sept. 2013 Slide 28Minho Cheong (ETRI)