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。