Adaptive MMSE Multiuser Detection (A-MMSE-MUD) in Asynchronous Cooperative CDMA Networks

Asynchronous cooperative CDMA wireless network uplink transmission is examined in this paper, where users cooperate in a relaying mode while they exchange data and channel information with the base station to achieve diversity gains. MAI occurs at both the relays and destination due to asynchronous transmission and non orthogonality of spreading waveform. In order to deal MAI, A-MMSE-MUD is been used by bank of linear adaptive filters. Two protocols of cooperative communication wireless networks are used, (i) amplify and forward at relays and A-MMSE-MUD at destination, (ii) A-MMSE-MUD at the relays and destination in a decode and forward operation. We compared our result with other multiuser detection schemes under same conditions in a cooperative communication wireless network and found that the amplify and forward scheme in use of A-MMSE-MUD remove the MAI even amplification is been performed on the relays nodes. Where as decode and forward scheme outperform all other multiuser detection scheme. Simulation experiments shows both schemes amplify and forward and decode and forward with A-MMSE-MUD provide significant improvement in the bit error rate and capacity performance of the cooperative communication CDMA networks.