doc.: IEEE 802.22-06/0125r0
July 2006
Interference Detection for Sensing
Authors:
IEEE P802.22 Wireless RANs
Name
Company
Address
Date: 2006-07-14
Phone
email
Linjun Lv
Huawei Technologies
Shenzhen, China
0086-755-28973119
[email protected]
Soo-Young Chang
Huawei Technologies
Davis, CA, U.S.
1-916 278 6568
[email protected]
Zhou Wu
Huawei Technologies
Shenzhen, China
86-755-28979499
[email protected]
Jun Rong
Huawei Technologies
Shenzhen, China
86-755-28979499
[email protected]
Mingwei Jie
Huawei Technologies
Shenzhen, China
86-755-28972660
[email protected]
Jianwei Zhang
Huawei Technologies
Shanghai, China
86-21-68644808
[email protected]
Lai Qian
Huawei Technologies
Shenzhen, China
86-755-28973118
[email protected]
Jianhuan Wen
Huawei Technologies
Shenzhen, China
86-755-28973121
[email protected]
Jun Wang
UESTC
Chengdu, China
86-28-83206693
[email protected]
Shaoqian Li
UESTC
Chengdu, China
86-28-83202174
[email protected]
Qihang Peng
UESTC
Chengdu, China
86-13096307946
[email protected]
Lei Chen
UESTC
Chengdu, China
86-13880765377
[email protected]
Meng Zeng
UESTC
Chengdu, China
86-13568886741
[email protected]
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Huawei
Carl
R. Stevenson as early as possible, in written or electronic form, if patented technology
developed
Submission
Slide (or
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>
doc.: IEEE 802.22-06/0125r0
July 2006
TWO INTERFERENCE DETECTIONS
• Orthogonal Interference Detection
• Interference Detection Using Preambles
Incumbent Signal Detection without Service
Interruption can be achieved.
Submission
Slide 2
Huawei
doc.: IEEE 802.22-06/0125r0
July 2006
INTRODUCTION
channel
Hk,i
Transmitter of
WRAN system
•
interference
Ik,i
noise
nk,i
OFDM
signal
Xk,i
Receiver of
WRAN system
If interference exists in the frequency domain of the received
signals:
Yk ,i＝X k ,i H k ,i＋I k ,i＋n k ,i
•
otherwise:
Yk ,i＝X k ,i H k ,i＋n k ,i
Submission
Slide 3
Huawei
doc.: IEEE 802.22-06/0125r0
July 2006
(1) Orthogonal Interference Detection
• Assume in coherence time and coherence bandwidth, Hk,i is
constant.
• Assume (Qk,i, Qk,i+1 ) is orthogonal to transmitted data (Xk,i, Xk,i+1 )
• A group of received data (Yk,i, Yk,i+1 ) are correlated with orthogonal
signal.
if interference exists:
Yk ,i Qk ,i＋Yk ,i＋1Q k ,i＋1＝I k ,i Qk ,i＋I k ,i＋1Q k ,i＋1＋n k ,i Q k ,i＋n k ,i＋1Q k ,i＋1
else:
Yk ,i Q k ,i＋Yk ,i＋1Q k ,i＋1＝n k ,i Qk ,i＋n k ,i＋1Q k ,i＋1
• Determine whether interference exists using energy detection:
2
if Yk ,i Q k ,i  Yk ,i 1Q k ,i 1  T(X k ,i , X k ,i＋1 ) , interference exists
else, interference does not exist.
Submission
Slide 4
Huawei
doc.: IEEE 802.22-06/0125r0
July 2006
Orthogonal Interference Detection Technology
•
•
Use multi groups of received data to increase reliability of the detection
Using data of N different time slots to form N-1 group of signal vectors
N 1
When

Yk ,i Q k ,i  Yk ,i 1Q k ,i 1
i 1
2
T(X k ,i , X k ,i＋1 )
1
N 1
•
, interference exists
Using data of N different sub-carriers to form N-1 group of signal vectors
N 1
When

k 1
Yk ,i Q k ,i  Yk 1,i Q k 1,i
T(X k ,i , X k 1,i )
N 1
Submission
2
1
, interference exists
Slide 5
Huawei
doc.: IEEE 802.22-06/0125r0
July 2006
Orthogonal Interference Detection Using Pilot
•
•
The location of a pilot is known
When Xk,i at location of pilot is always “1” ,the formula is
N 1
 Yk ,i  Yk ,i1
i 1
N 1
•
2
 T(1,1)
When Xk,i at location of pilot is alternatingly “1” and “-1” ,the formula is
N 1
Y
i 1
k ,i＋Yk ,i 1
N 1
Submission
2
 T(1,1)
Slide 6
Huawei
doc.: IEEE 802.22-06/0125r0
July 2006
Orthogonal Interference Detection Using Traffic Data
• Traffic data is richer than pilot for
interference detection
• Received symbols Yk,i are buffered
• Coding and modulation to get Xk,i
• If correct in decoding ,then detect
interference based on the
algorithm mentioned in the
previous slide
• If errors in decoding ,then
calculate PER (Packet Error
Ratio) :
If PER>threshold, BS will
schedule quiet periods
Submission
Slide 7
received
signal
OFDM
demodulation
decoding
coding
Interference
detection
modulation
Interference Detection in receiver
Huawei
doc.: IEEE 802.22-06/0125r0
July 2006
Simulation 1
Orthogonal Detection INR=30dB
detction probability
1
0.8
0.6
0.4
0.2
0
-300
-200
-100
0
100
200
subcarrier number
Accumulative Orthogonal Detection INR=30dB
-200
-100
300
detction probability
1
0.8
0.6
0.4
0.2
0
-300
0
100
subcarrier number
200
300
Detection probabilities under INR=30dB of the algorithm. The upper figure illustrates
the detection with one group of symbols while the bottom one illustrates the detection
with average of 8 groups of symbols.
Submission
Slide 8
Huawei
doc.: IEEE 802.22-06/0125r0
July 2006
Simulation 2
Orthogonal Detection INR=20dB
detction probability
1
0.8
0.6
0.4
0.2
0
-300
-200
-100
0
100
200
subcarrier number
Accumulative Orthogonal Detection INR=20dB
-200
-100
300
detction probability
1
0.8
0.6
0.4
0.2
0
-300
0
100
subcarrier number
200
300
Detection probabilities under INR=20dB of the algorithm. The upper figure illustrates
the detection with one group of symbols while the bottom one illustrates the detection
with average of 8 groups of symbols.
Submission
Slide 9
Huawei
doc.: IEEE 802.22-06/0125r0
July 2006
Simulation 3
Orthogonal Detection INR=0dB
detction probability
0.2
0.15
0.1
0.05
0
-300
-200
200
100
0
subcarrier number
Accumulative Orthogonal Detection INR=0dB
300
200
300
-100
detction probability
0.2
0.15
0.1
0.05
0
-300
-200
-100
100
0
subcarrier number
Detection probabilities under INR=0dB of the algorithm. The upper figure illustrates
the detection with one group of symbols while the bottom one illustrates the detection
with average of 8 groups of symbols.
Submission
Slide 10
Huawei
doc.: IEEE 802.22-06/0125r0
July 2006
Conclusions of Orthogonal Interference Detection
• Interference Detection can be done without channel estimation
• Interference Detection can be done without Service Interruption
• Multiple groups of received data can be used to increase
detection reliability
• Joint with Decoding and Demodulation
Submission
Slide 11
Huawei
doc.: IEEE 802.22-06/0125r0
July 2006
(2) Interference Detection Using Preambles
• Assume the system bandwidth is 6MHz
• PN can be training sequences of frame preambles for
downlink frame
• PN can be training sequences of burst preambles for
uplink frame
PN
PN1
all zeros
PN2
PN3
PN4
short
pseudo sequence
PN5
PN6
Submission
Slide 12
Huawei
doc.: IEEE 802.22-06/0125r0
July 2006
Correlation of PNi and PN
1000
500
0
0
500
1000
1500
2000
2500
0
500
1000
1500
2000
2500
0
500
1000
1500
2000
2500
0
500
1000
1500
2000
2500
0
500
1000
1500
2000
2500
0
500
1000
1500
2000
2500
1000
500
0
1000
500
0
1000
500
0
1000
500
0
1000
500
0
Submission
Slide 13
Huawei
doc.: IEEE 802.22-06/0125r0
July 2006
Technology of Interference Detection Using Preambles
•
The transmitted signal (PNm) has correlation with the received signal
Y
X k , i   H i X k ,i X k , i
*
k ,i
k
•
k ,iYk ,i  H i
*
k
2
X
X k ,i   I k , i I k , i   n k ,i n k ,i
*
k ,i
k
*
k
*
k
Then get sum of power of interference and noise based on the second equation
I
k
•
k
Energy of the received signal
Y
•
*
I
k ,i k ,i
*
  n k ,i n k ,i  Yk ,iYk ,i  H i
*
k
*
k
2
X
k ,i
X k ,i
*
k
Calculate sum of interference and noise power for each fractional bandwidth, and
compare the power with pre-determined threshold. If interference and noise power is
larger than the threshold, there is interference on this part of bandwidth.
Submission
Slide 14
Huawei
doc.: IEEE 802.22-06/0125r0
July 2006
Simulation 1
1
1
0.9
0.9
0.8
0.7
0.7
False alarmProbability
Detection Probability
0.8
0.6
0.5
0.4
0.3
0.2
0.6
0.5
0.4
0.3
0.2
0.1
0.1
1.26
1.28
1.3
1.32
1.34
1.36
1.38
1.4
1.42
1.44
1.46
0
0.16
0.18
0.2
0.22
0.24
0.26
0.28
0.3
0.32
threshold
threshold
Performance of interference detection using frame preambles, INR = 0dB
Submission
Slide 15
Huawei
0.34
0.36
doc.: IEEE 802.22-06/0125r0
July 2006
Simulation 2
1
0.9
0.9
0.8
0.8
0.7
0.7
False alarmProbability
Detection Probability
1
0.6
0.5
0.4
0.3
0.2
0.5
0.4
0.3
0.2
0.1
0.1
0
0.24
0.6
0.26
0.28
0.3
0.32
0.34
0.36
0.38
0.4
0.42
0.44
0
0.16
0.18
0.2
0.22
0.24
0.26
0.28
0.3
0.32
threshold
threshold
Performance of interference detection using frame preambles, INR = -10dB
Submission
Slide 16
Huawei
0.34
0.36
doc.: IEEE 802.22-06/0125r0
July 2006
Simulation 3
1
0.9
0.8
Detection Probability
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
-20
-18
-16
-14
-12
-10
-8
-6
-4
-2
0
INR(dB)
Detection probability VS INR of interference detection using frame preambles
for threshold =0.25
Submission
Slide 17
Huawei
doc.: IEEE 802.22-06/0125r0
July 2006
Conclusions of Interference Detection with Preambles
• Interference Detection can be done without channel
estimation
• Interference Detection can be done without Service
Interruption
• Do not need to schedule QPs, without increasing overhead
• It can be applied for Fractional bandwidth detection
Submission
Slide 18
Huawei