Cooperative Communication in Wireless Networks Aria Nosratinia, University of Texas, Dallas, Todd E. Hunter, Nortel Networks Ahmadreza 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 relaydestination

Cooperative Communication Amplify and forward Decode and forward Coded cooperation

Decode an d forward Assumption  each user transmits its own bits detects the other user’s second bit

Decode an d 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 ：

Decode an d 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

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

Performance

User 1 User 2 destination SNR=X+10 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。