ABSTRACT Cooperative diversity is a promising technology for future wireless networks. In this paper, we consider a cooperative communication system operating in an amplify-and-forward (AF) mode with a pilot symbol as-sisted modulation (PSAM) scheme. It is assumed that a linear minimum mean square estimator (LMMSE) is used for the channel estimation at the receiver. A simple and easy-to-evaluate asymptotical upper bound (AUB) of the symbol-error-rate (SER) is derived for uncoded AF cooperative communication systems with quadrature amplitude modulation (QAM) constellations. Based on the AUB, we propose a criterion for the parameter optimization in the PSAM scheme. We discuss how the pilot spacing and the length of the Wiener ?lter should be chosen under the constraint of a tradeoff between pilot overhead, estimation accuracy, and receiver complexity. We also formulate an power allocation problem for the considered system. It is shown that the power allocation problem can optimally be solved by means of a gradient search method. Numerical simulations are presented to verify the correctness of the theoretical results and to demonstrate the benefits of the parameter optimization.
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nullY. WU and M. PATZOLD, "Parameter Optimization for Amplify-and-Forward Relaying Systems with Pilot Symbol Assisted Modulation Scheme," Wireless Sensor Network, Vol. 1 No. 1, 2009, pp. 15-21. doi: 10.4236/wsn.2009.11003.
 G. Kramer, M. Gastpar, and P. Gupta, “Cooperative strategies and capacity theorems for relay networks,” IEEE Transactions on Information Theory, Vol. 51, No. 9, pp. 3037-3063, September 2005.
 A. Reznik, M. R. Kulkarni, and S. Verdu, “Degraded Gaussian multirelay channel: Capacity and optimal power allocation,” IEEE Transactions on Information Theory, Vol. 50, No. 12, pp. 3037-3046, December 2004.
 A. Host-Madsen and J. Zhang, “Capacity bounds and power allocation for wireless relay channels,” IEEE Transactions on Information Theory, Vol. 51, No. 6, pp. 2020-2040, June 2005.
 J. N. Laneman, D. N. C. Tse, and G. W. Wornell, “Cooperative diversity in wireless networks: Efficient protocols and outage behavior,” IEEE Transactions on Information Theory, Vol. 50, No. 12, pp. 3062-3080, December 2004.
 C. S. Patel and G. L. Stüber, “Channel estimation for amplify and forward relay based cooperation diversity systems,” IEEE Transactions on Wireless Communications, Vol. 6, No. 6, pp. 2348–2356, June 2007.
 R. U. Nabar, H. B?lcskei, and F. W. Kneubühler, “Fading relay channels: Performance limits and space-time signal design,” IEEE Journal on Selected Areas in Communications, Vol. 22, No. 6, pp. 1099-1109, August 2004.
 M. O. Hasna and M.-S. Alouini, “Harmonic mean and end-to-end performance of transmission systems with relays,” IEEE Transactions on Communications, Vol. 52, No. 1, pp. 130-135, January 2004.
 M. O. Hasna and M.-S. Alouini, “A performance study of dual-hop transmissions with fixed gain relays,” IEEE Transactions on Wireless Communications, Vol. 3, No. 6, pp. 1963-1968, November 2004.
 P. A. Anghel and M. Kaveh, “Exact symbol error probability of a cooperative network in a Rayleigh-fading environment,” IEEE Transactions on Wireless Communications, Vol. 3, No. 5, pp. 1416-1421, September 2004.
 A. Ribeiro, X. Cai, and G. B. Giannakis, “Symbol error probabilities for general cooperative links,” IEEE Transactions on Wireless Communications, Vol. 4, No. 3, pp. 1264-1273, March 2005.
 Y. Li and S. Kishore, “Asymptotic analysis of amplify- and-forward relaying in Nakagami-fading environments,” IEEE Transactions on Wireless Communications, Vol. 6, No. 12, pp. 4256-4262, December 2007.
 W. Su, A. K. Sadek, and K. J. R. Liu, “Cooperative communication protocols in wireless networks: Performance analysis and optimum power allocation,” Wireless Personal Communications (Springer), Vol. 44, No. 2, pp. 181-217, January 2008.
 B. Gedik and M. Uysal, “Two channel estimation methods for amplify-and-forward relay networks,” in Proceedings of Canadian Conference on Electrical and Computer Engineering , pp. 615-618, May 2008.
 Y. Wu and M. P?tzold, “Performance analysis of cooperative communication systems with imperfect channel estimation,” IEEE International Conference on Communications, IEEE ICC 2009, accepted for publication, June 2009.
 L. L. Scharf, “Statistical signal processing: Detection, estimation, and time-series analysis,” Reading, MA: Addison-Wesley, 1990.
 D. G. Brennan, “Linear diversity combining techniques,” Proceedings of the IEEE, Vol. 91, No. 2, pp. 331-356, February 2003.