Embed Size (px)
DESCRIPTION
Introduction The mobile wireless channel suffers from fading signal attenuation can vary significantly Transmitting independent copies of the signal from different location generates spatial diversity effectively combat fading
Citation preview
Cooperative Communication inWireless Networks
Aria Nosratinia, University of Texas, Dallas, Todd E. Hunter, Nortel NetworksAhmadreza Hedayat, University of Texas, Dallas
Speaker ： Ching-Chung Lin
IEEE Communications Magazine October 2004
Outline
Introduction Assumption Cooperative Communication Performance Conclusion
Introduction
The mobile wireless channel suffers from fading signal attenuation can vary significantly
Transmitting independent copies of the signal from different location generates spatial diversity effectively combat fading
A
B C
Assumption
One antenna Each host have one partner
may be assigned mutually by the base station Each host is a both a user and a relay One cooperator forward “overheard” information
Cooperative Communication
Amplify and forward Decode and forward Coded cooperation
Cooperative Communication
Amplify and forward Decode and forward Coded cooperation
Amplify and forward
Assumption Each user receives a noisy version of the signal transmitted by
its partner The base station knows the interuser channel coefficients to do
optimal decoding
A
B C
User
relay
destination
Cooperative Communication
Amplify and forward Decode and forward Coded cooperation
Decode and forward
Assumption each user
transmits its own bits detects the other user’s second bit
Decode and forward
symbol definition each user has its own spreading code
C1(t) C2(t) two user’s data bits
Signal amplitudes i ： transmission interval j ： power level ex ：
)(1nb )(
2nb
j ia
2 1a 1 2a
Decode and forward
)]()( , )( , )([)( 2)2(
2141)2(
1131)2(
1121)1(
1111 tcbatcbatcbatcbatX
)]()( , )( , )([)( 2)2(
2241)2(
1232)2(
2222)1(
2212 tcbatcbatcbatcbatX
Decode and forward
)]()( , )( , )([)( 2)2(
2141)2(
1131)2(
1121)1(
1111 tcbatcbatcbatcbatX
)]()( , )( , )([)( 2)2(
2241)2(
1232)2(
2222)1(
2212 tcbatcbatcbatcbatX
Decode and forward
)]()( , )( , )([)( 2)2(
2141)2(
1131)2(
1121)1(
1111 tcbatcbatcbatcbatX
)]()( , )( , )([)( 2)2(
2241)2(
1232)2(
2222)1(
2212 tcbatcbatcbatcbatX
Decode and forward
J. N. Laneman, G. W. Wornell, and D. N. C. Tse, “An Efficient Protocol for Realizing Cooperative Diversity in Wireless
Networks,” Proc. IEEE ISIT, Washington, DC,June 2001
When the SNR is high , user enter into cooperative mode. When the SNR is low , user enter into noncooperative mode.
Cooperative Communication
Amplify and forward Decode and forward Coded cooperation
Coded cooperation
each user decode the transmission of its partner data is encoded into a codeword
N bits = N1 + N2
A
B C
N1 bits : userA’s data
Frame1
N2 bits : userA’s data
Frame2
N1 bits : userB’s data
Frame1
N2 bits : userB’s data
Frame2
A
B C
N1 bits : userA’s data
Frame1
N1 bits : userB’s data
Frame1
Performance
rate-compatible punctured convolutional (RCPC) codes
User 1
User 2
destination
SNR=X
SNR=X
SNR=X
Performance
User 1
User 2
destination
SNR=X+10
SNR=X
SNR=X
Performance
conclusion
Results to date are indicative of a promising future for cooperative communication.
Thank You
英 文： Block Error Rate (BKER, BLER) 台 灣： 塊誤率 大 陸： N/A 修訂時間： 2000/9/13
字組錯誤率，數據組出錯率，信息組差錯率錯誤地接收方塊 (Blocks) 的數目和送出方塊總數目的比率，來衡量塊處理效果。
