1. doc.: IEEE 802.11-03/522r2 Submission July 2003 N.Kita, Y.Inoue, NTTSlide 1 Multipath Delay Profiles in a 5GHz band Naoki Kita and Yasuhiko Inoue NTT {nkita,yinoue}@ansl.ntt.co.jp

2. doc.: IEEE 802.11-03/522r2 Submission July 2003 N.Kita, Y.Inoue, NTTSlide 2 Background#1 5GHz band wireless access systems –4.9 - 5.0 GHz, 5.030 - 5.091 GHz –Technical requirements Radio Equipment Ordinance: Article 49-21 In the near future, 5.25-5.35GHz band and 5.47- 5.725GHz will be assigned for wireless access services. –Requirements are not specified yet.

3. doc.: IEEE 802.11-03/522r2 Submission July 2003 N.Kita, Y.Inoue, NTTSlide 3 Background#2 Market –Plans for FWA and NWA services: A local government is planning to install a great number of base stations to cover whole region of the city. Another city plans to install 10,000 FWA devices. Many other local governments and public organizations will follow them. Group company of NTT also plans to provide wireless internet services using this system. Other companies such as SONY and Speed Net, have their plans.

4. doc.: IEEE 802.11-03/522r2 Submission July 2003 N.Kita, Y.Inoue, NTTSlide 4 Background#3 Japanese frequency regulations for 4.9-5.0GHz and 5.030-5.091GHz allows three kinds of systems: – 20MHz channel bandwidth PHY data rates: 6, 9, 12, 18, 24, 36, 48, 54M bit/s – 10MHz channel bandwidth PHY data rates: 3, 4.5, 6, 9, 12, 18, 24, 27M bit/s – 5MHz channel bandwidth PHY data rates: 1.5, 2.25, 3, 4.5, 6, 9, 12, 13.5M bit/s

5. doc.: IEEE 802.11-03/522r2 Submission July 2003 N.Kita, Y.Inoue, NTTSlide 5 Purpose of this presentation FWA and NWA services using 5GHz band wireless access systems: –based on 802.11a PHY –Outdoor environment –Long range (up to 3Km) To evaluate if the 802.11a PHY has enough immunity for delay spread based on the results of measurements Performance of the 802.11a PHY can be degraded because of delay spread

6. doc.: IEEE 802.11-03/522r2 Submission July 2003 N.Kita, Y.Inoue, NTTSlide 6 802.11a PHY 20MHz channel spacing systems: –Tolerable delay spread will be < 200 or 250[ns] 10MHz channel spacing systems: –Tolerable delay spread will be < 400 or 500[ns] ? GI 8 [us] 1.6 [us] time GI 4 [us] 0.8 [us] time 1/2 clock rate

7. doc.: IEEE 802.11-03/522r2 Submission July 2003 N.Kita, Y.Inoue, NTTSlide 7 Results of measurements Scenarios –FWA: Typical residential are in Tokyo –NWA: Typical urban area in Tokyo

8. doc.: IEEE 802.11-03/522r2 Submission July 2003 N.Kita, Y.Inoue, NTTSlide 8 The FWA Scenarios The Base station and subscriber stations Base station Omni-directional antenna Antenna height = 18, 21[m] Antenna Subscriber station Omni-directional antenna Antenna height = 5, 10[m] Antenna

9. doc.: IEEE 802.11-03/522r2 Submission July 2003 N.Kita, Y.Inoue, NTTSlide 9 The FWA Scenarios (Cont’d) Measurement points 1 2 3 4 5 6789 10 11 12 13 14 15 16 17 18 2019 21 22 23 24 25

10. doc.: IEEE 802.11-03/522r2 Submission July 2003 N.Kita, Y.Inoue, NTTSlide 10 The FWA Scenarios (Cont’d) Residential area in Tokyo

11. doc.: IEEE 802.11-03/522r2 Submission July 2003 N.Kita, Y.Inoue, NTTSlide 11 The FWA Scenarios (Cont’d) An example of delay profile -130 -120 -110 -100 -90 -80 -70 0500 (1.7[us]) 1000 (3.3[us]) 1500 (5.0[us]) 2000 (6.7[us]) Received level [dBm] Antenna height: Tx; ht = 18.0[m] Rx: hr = 2.8[m] Distance between Tx and Rx modules = 250[m] Spread: 205.1[ns]

12. doc.: IEEE 802.11-03/522r2 Submission July 2003 N.Kita, Y.Inoue, NTTSlide 12 The FWA Scenario (Cont’d) Another example of delay profile -130 -120 -110 -100 -90 -80 -70 0500 (1.7[us]) 1000 (3.3[us]) 1500 (5.0[us]) 2000 (6.7[us]) Received Signal Level [dBm] Antenna height: Tx; ht = 18.0[m] Rx: hr = 2.8[m] Distance between Tx and Rx modules = 875[m] Spread: 62.505[ns]

13. doc.: IEEE 802.11-03/522r2 Submission July 2003 N.Kita, Y.Inoue, NTTSlide 13 The FWA Scenarios (Cont’d) Cumulative Probability 0100200300400500600700 0.01 0.1 1 5 10 20 30 50 70 80 90 95 99 99.9 99.99 Delay spread [nsec] Cumulative probability (%) ht=18m, hr=5m ht=18m, hr=10m 050100150200250300 Delay spread [nsec] ht=21m, hr=5m ht=21m, hr=10m

14. doc.: IEEE 802.11-03/522r2 Submission July 2003 N.Kita, Y.Inoue, NTTSlide 14 The FWA Scenarios (Cont’d) Summary –Delay Spread depends on: antenna height of the BSs and subscriber stations reflectors –In FWA cases, 90% value of delay spread will be less than 200[ns]. if base station and subscriber station are appropriately installed. LOS helps to reduce the delay spread.

15. doc.: IEEE 802.11-03/522r2 Submission July 2003 N.Kita, Y.Inoue, NTTSlide 15 The NWA Scenario Ginza areaNihonbashi Area Pictures from the base station’s antenna height Pictures from the mobile station’s antenna height

16. doc.: IEEE 802.11-03/522r2 Submission July 2003 N.Kita, Y.Inoue, NTTSlide 16 The NWA Scenarios (Cont’d) Measured area Map of experimental area in Tokyo - 1 (Ginza area) Map of experimental area in Tokyo - 2 (Nihonbashi area) Tx 100m 200m 300m400m Ginza 8 Ginza 6 Dentsu SONY Tx 100m 200m 300m 400m 500m 600m Nihonbashi 1 Kyobashi 1 Nihonbashi 2 Nihonbashi 3

17. doc.: IEEE 802.11-03/522r2 Submission July 2003 N.Kita, Y.Inoue, NTTSlide 17 The NWA Scenarios (Cont’d) Median of the delay spread 0 100 200 300 400 0 50 100 200300400500600700 Median of delay spread [nsec] Distance between Tx and Rx [m] Standard deviation [nsec] Ginza area Nihonbashi

18. doc.: IEEE 802.11-03/522r2 Submission July 2003 N.Kita, Y.Inoue, NTTSlide 18 The NWA Scenarios (Cont’d) 90% value vs. median of delay spread 0 100 200 300 400 500 600 700 50100150 200 250 300350 90% value of delay spread [nsec] Median of delay spread [nsec] 90% value of cumulative delay spread: 350[ns] 20MHz channel spacing systems do not have enough immunity

19. doc.: IEEE 802.11-03/522r2 Submission July 2003 N.Kita, Y.Inoue, NTTSlide 19 The NWA Scenarios (Cont’d) Summary –90% value of the delay spread in the NWA environments will be 350[ns]. –20MHz channel spacing systems will not be enough. –10MHz channel spacing system is desired if we hope to support this kind of services.

20. doc.: IEEE 802.11-03/522r2 Submission July 2003 N.Kita, Y.Inoue, NTTSlide 20 Conclusion Measured delay spread (90% value): –About 200[ns] for the FWA scenarios. If the base stations and subscriber stations are installed appropriately. If not, delay spread increases (can be 400 ~ 500[ns]). –About 350[ns] for the NWA scenarios. Not tolerable for the 20MHz channel spacing systems. 802.11j should include specifications for 10MHz channel spacing systems as well as 20MHz channel spacing systems.