Channel Estimation for Amplify and Forward Relay Based Cooperation Diversity Systems

Cooperation diversity schemes have been proposed for cellular networks that permit a base station (or a mobile station) to relay signals to a destination receiver, thereby increasing the network coverage and reliability. The mobile relays either decode and forward (DF) or amplify and forward (AF) the received signal. Most existing analyses of cooperation diversity assumes perfect channel information at the receiver. A realistic assessment should consider the effects of practical channel estimation schemes. This paper considers pilot symbol aided channel estimation for cooperation diversity systems. Since the overall channel in AF systems is different from conventional cellular channels, the channel estimation problem is interesting and challenging and therefore our focus is on AF systems. The paper addresses issues such as the estimator design, pilot symbol spacing based upon realistic channel models, and an approximate bit error rate (BER) analysis that accounts for imperfect channel estimation.