1. Mutipath Delay Profiles in a 5GHz band
July 2003
Mutipath Delay Profiles in a 5GHz band
Naoki Kita and Yasuhiko Inoue
NTT
N.Kita, Y.Inoue, NTT

2. Background#1 5GHz band wireless access systems
July 2003
Background#1
5GHz band wireless access systems
GHz, GHz
Technical requirements
Radio Equipment Ordinance: Article 49-21
In the near future, GHz band and GHz will be assigned for wireless access services.
Requirements are not specified yet.
N.Kita, Y.Inoue, NTT

3. Background#2 Market Plans for FWA and NWA services:
July 2003
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.
N.Kita, Y.Inoue, NTT

4. July 2003
Background#3
Japanese frequency regulations for GHz and GHz 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
N.Kita, Y.Inoue, NTT

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

6. 802.11a PHY 20MHz channel spacing systems:
July 2003
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] ?
4 [us]
0.8 [us]
1/2 clock rate GI
time
8 [us]
1.6 [us] GI
time
N.Kita, Y.Inoue, NTT

7. Results of measurements
July 2003
Results of measurements
Scenarios
FWA:
Typical residential are in Tokyo
NWA:
Typical urban area in Tokyo
N.Kita, Y.Inoue, NTT

8. The FWA Scenarios The Base station and subscriber stations Antenna
July 2003
The FWA Scenarios
The Base station and subscriber stations
Antenna
Antenna
Base station
Omni-directional antenna
Antenna height = 18, 21[m]
Subscriber station
Omni-directional antenna
Antenna height = 5, 10[m]
N.Kita, Y.Inoue, NTT

9. The FWA Scenarios (Cont’d)
July 2003
The FWA Scenarios (Cont’d)
Measurement points 18 20 19 6 7 8 9 13 17 14 1 12 5 4 10 16 24 11 15 21 25 3 2 22 23
N.Kita, Y.Inoue, NTT

10. The FWA Scenarios (Cont’d)
July 2003
The FWA Scenarios (Cont’d)
Residential area in Tokyo
N.Kita, Y.Inoue, NTT

11. The FWA Scenarios (Cont’d)
July 2003
The FWA Scenarios (Cont’d)
An example of delay profile
-70
Antenna height:
Tx; ht = 18.0[m]
Rx: hr = 2.8[m]
Distance between Tx and Rx
modules = 250[m]
Spread: 205.1[ns]
-80
-90
Received level [dBm]
-100
-110
-120
-130
500
(1.7[us])
1000
(3.3[us])
1500
(5.0[us])
2000
(6.7[us])
N.Kita, Y.Inoue, NTT

12. The FWA Scenario (Cont’d)
July 2003
The FWA Scenario (Cont’d)
Another example of delay profile
-70
Antenna height:
Tx; ht = 18.0[m]
Rx: hr = 2.8[m]
Distance between Tx and Rx
modules = 875[m]
Spread: [ns]
-80
-90
Received Signal Level [dBm]
-100
-110
-120
-130
500
(1.7[us])
1000
(3.3[us])
1500
(5.0[us])
2000
(6.7[us])
N.Kita, Y.Inoue, NTT

13. The FWA Scenarios (Cont’d)
July 2003
The FWA Scenarios (Cont’d)
Cumulative Probability
99.99
99.9 99 95 90 80 70
Cumulative probability (%) 50 30 20 10 5
ht=21m, hr=5m
ht=21m, hr=10m 1
ht=18m, hr=5m
0.1
ht=18m, hr=10m
0.01
100
200
300
400
500
600
700 50
100
150
200
250
300
Delay spread [nsec]
Delay spread [nsec]
N.Kita, Y.Inoue, NTT

14. The FWA Scenarios (Cont’d)
July 2003
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.
N.Kita, Y.Inoue, NTT

15. The NWA Scenario Pictures from the base station’s antenna height
July 2003
The NWA Scenario
Ginza area
Nihonbashi Area
Pictures from
the base station’s
antenna height
Pictures from
the mobile station’s
antenna height
N.Kita, Y.Inoue, NTT

16. The NWA Scenarios (Cont’d)
July 2003
The NWA Scenarios (Cont’d)
Measured area Tx
100m
200m
300m
400m
Ginza 8
Ginza 6
Dentsu
SONY
Map of experimental area in Tokyo - 1 (Ginza area) Tx
100m
200m
300m
400m
500m
600m
Nihonbashi 1
Kyobashi 1
Nihonbashi 2
Nihonbashi 3
Map of experimental area in Tokyo - 2 (Nihonbashi area)
N.Kita, Y.Inoue, NTT

17. The NWA Scenarios (Cont’d)
July 2003
The NWA Scenarios (Cont’d)
Median of the delay spread
100
200
300
400 50
500
600
700
Median of delay spread
[nsec]
Distance between Tx and Rx [m]
Standard deviation
Ginza area
Nihonbashi
N.Kita, Y.Inoue, NTT

18. The NWA Scenarios (Cont’d)
July 2003
The NWA Scenarios (Cont’d)
90% value vs. median of delay spread
100
200
300
400
500
600
700 50
150
250
350
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
N.Kita, Y.Inoue, NTT

19. The NWA Scenarios (Cont’d)
July 2003
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.
N.Kita, Y.Inoue, NTT

20. Conclusion Measured delay spread (90% value):
July 2003
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.
N.Kita, Y.Inoue, NTT