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Cooperative Communication in Wireless Networks. Aria Nosratinia, University of Texas, Dallas, Todd E. Hunter, Nortel Networks Ahmadreza Hedayat, University of Texas, Dallas. IEEE Communications Magazine October 2004. Speaker : Ching-Chung Lin. Outline. Introduction Assumption
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Cooperative Communication inWireless Networks Aria Nosratinia, University of Texas, Dallas, Todd E. Hunter, Nortel Networks Ahmadreza Hedayat, University of Texas, Dallas IEEE Communications Magazine October 2004 Speaker:Ching-Chung Lin
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
B C A
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 versionof the signal transmitted by its partner • The base station knows the interuser channel coefficients to do optimal decoding
B C relay destination A User
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:
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
Frame2 Frame1 N2 bits : userA’s data N1 bits : userB’s data B C Frame1 Frame2 N1 bits : userA’s data N2 bits : userB’s data A
Frame1 N1 bits : userB’s data B C Frame1 N1 bits : userA’s data A
Performance • rate-compatible punctured convolutional (RCPC) codes
User 2 destination SNR=X SNR=X SNR=X User 1
User 2 destination SNR=X SNR=X SNR=X+10 User 1
conclusion • Results to date are indicative of a promising future for cooperative communication.
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。