Global Standards Collaboration (GSC) 14
DOCUMENT #:
GSC14-PLEN-071
FOR:
Presentation
SOURCE:
ARIB
AGENDA ITEM:
6.2
CONTACT(S):
homa@nict.go.jp
Broadband Wireless Communication System
for Public Safety
Homare Murakami, Masayuki Oodo, Hiroshi Harada
NICT / ARIB
Geneva, 13-16 July 2009
Fostering worldwide interoperability
Background
– frequency band–
In Japan, digitalization of terrestrial TV broadcasting service to be completed
in July, 2011 == > reduce the total bandwidth for terrestrial TV broadcasting
current analog TV broadcasting (total: 370 MHz)
90 108
170
222
470
770 [MHz]
current
1.mobile multimedia
broadcasting
after July,
2011
90 108
170
205 222
470
710 720 730
770[MHz]
terrestrial digital TV
3.ITS 4.cellular
broadcasting (240 MHz)
system
==> 130 MHz newly available
2. Broadband mobile communications for public safety
Geneva, 13-16 July 2009
Fostering worldwide interoperability
2
Strategic Direction
– current and expected systems for public safety–
current system
local government
(prefectural/city/municipal)
-- narrow band
fire department
voice
narrow
low data rate transmission
band
-- difficulty in interoperability
police agencies
narrow
band
difficulty in
interoperability
expected system
-- shared by multiple public organizations broadband
-- broadband access service (several Mbps)
for mobile users
(main application: moving
pictures transmission)
-- highly-efficient spectrum use
=> OFDM-based system
Geneva, 13-16 July 2009
shared by multiple
public organizations
Fostering worldwide interoperability
3
Challenges for reliability(1/2)
– Radio Propagation Field Tests –
RSSI measurement
=> coverage ~ 5 km
P4
00
relative power [dB]
peak time
+10sec
-10
0
-10
-10
peak time
+20sec
relative amplitude [dB]
relative power [dB]
@P4
-20
-20
-20
-30
200
-40
time
100 [msec]
-50
-60
-5
0
frequency [MHz]
0
5
fading performance:
=> slow temporal variation
Geneva, 13-16 July 2009
@P4
d=1.6km
delay spread:
=> ~ 10usec
-30
-30
-40
-40
-50
-50
0
0
5
10
10
15
time [usec]
time [sec]
20
20
Fostering worldwide interoperability
25
30
30
4
Challenges for reliability (2/2)
– Transmission Experiments –
In order to investigate adequate OFDM parameters, following combinations were tested.
Mode #
Channel bandwidth
FFT Size
Guard Interval
Pilot symbol occupancy
Mode 1
5 MHz
512
~10 μsec
~30%
Mode 2
5 MHz
1024
~20 μsec
~30%
Mode 3
5 MHz
1024
~20 μsec
~17%
CN R vs B ER
（p r o fileA， CT C r=1/2， Q P SK）
CN R vs BER
（ty picalUrban ， CTC， QPSK）
1E+0
0
1E+0
-1
1E-1
10
-3
1E-3
10
mode4
B ER
-3
1E-3
10
BER
-2
1E-2
10
mode3
GSM Typical Urban
-1
1E-1
mode4
-2
1E-2
10
-4
1E-4
10
-4
1E-4
10
-5
1E-5
10
-5
1E-5
10
Mode1
Mode2
Mode3
-6
1E-6
10
-7
1E-7
10
mode2
伝搬路モデル： Typical Urban
mode3
BE R
BER
10
0
mode2
伝搬路モデル：802.22 Profile A
IEEE 802.22 Profile A
-6
1E-6
10
-7
1E-7
10
5
5
1010
Mode1
Mode2
Mode3
1515
2020
CNR [dB]
25 25
CN R [dB]
30
30
35
For long-delayed (~ 20μsec) channel environment,
Mode2 (narrower subcarrier interval, resulted in good
transmission performance.
Geneva, 13-16 July 2009
40
5
5
10
10
15
15
20
20
CNR [dB]
2525
30
30
35
CN R[dB]
For short-delayed (~ 5μsec) channel
environment, no large differences among all
modes were seen.
Fostering worldwide interoperability
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Next Steps/Actions
Toward the realization of broadband wireless
communication system for public safety using the
VHF bands (a portion of vacant lots after retirement
of analog TV broadcasting service),
R & D of the system have been progressed.
Indoor and Field experiments have been conducted
to decide the system parameters (service coverage,
PHY parameters etc.).
Geneva, 13-16 July 2009
Fostering worldwide interoperability
6