Adaptive modulation for cooperative communications with noisy feedback

Cooperative communication is an alternative way to generate spatial diversity. However due to the extra time slot required for relay transmission, the spectral efficiency (SE) is reduced. Adaptive modulation can optimize the spectral efficiency by adopting the transmission parameters to the channel conditions. This requires the perfect channel state information (CSI) feedback at the transmitter. However, in real life this is not practical. The feedback channel is noisy and fading which causes feedback errors. In this contribution, first we investigate the performance of adaptive modulation schemes for cooperative communications with perfect feedback, the adaptive modulation is applied both by the source and the relay. Then the impact of noisy feedback channels on the performance is analysed. The simulation results demonstrate the spectral efficiency improvement, and illustrates that the effect of the noisy feedback can be ignored when the feedback channel signal-to-noise ratio (SNR) is relatively high i.e. 10 dB.

[1]  Deqiang Chen User Cooperation Diversity , 2003 .

[2]  Mohamed-Slim Alouini,et al.  Joint Adaptive Modulation and Diversity Combining with Feedback Error Compensation , 2008, 2008 IEEE 68th Vehicular Technology Conference.

[3]  Abbas El Gamal,et al.  Capacity theorems for the relay channel , 1979, IEEE Trans. Inf. Theory.

[4]  Mohamed-Slim Alouini,et al.  Adaptive Modulation over Nakagami Fading Channels , 2000, Wirel. Pers. Commun..

[5]  Y.-F. Huang,et al.  Feedback Constraints for Adaptive Transmission , 2007, IEEE Signal Processing Magazine.

[6]  Seungkeun Park,et al.  An alternative expression for the symbol-error probability of MPSK in the presence of I/Q unbalance , 2004, IEEE Trans. Commun..

[7]  Michael Gastpar,et al.  Cooperative strategies and capacity theorems for relay networks , 2005, IEEE Transactions on Information Theory.

[8]  Elza Erkip,et al.  User cooperation diversity. Part I. System description , 2003, IEEE Trans. Commun..

[9]  Andrea J. Goldsmith,et al.  Variable-rate variable-power MQAM for fading channels , 1997, IEEE Trans. Commun..

[10]  Elza Erkip,et al.  User cooperation diversity. Part II. Implementation aspects and performance analysis , 2003, IEEE Trans. Commun..

[11]  A. Goldsmith,et al.  Variable-rate variable-power MQAM for fading channels , 1996, Proceedings of Vehicular Technology Conference - VTC.

[12]  Gregory W. Wornell,et al.  Cooperative diversity in wireless networks: Efficient protocols and outage behavior , 2004, IEEE Transactions on Information Theory.

[13]  V. Tarokh,et al.  Design and analysis of collaborative diversity protocols for wireless sensor networks , 2004, IEEE 60th Vehicular Technology Conference, 2004. VTC2004-Fall. 2004.

[14]  Yih-Fang Huang,et al.  Feedback-detection strategies for adaptive modulation systems , 2006, IEEE Transactions on Communications.