Abstract
In this paper, we propose an efficient precoding technique for cooperative wireless systems. The technique aims to reduce the effect of Inter-Symbol Interference (ISI) in cooperative transmissions over frequency-selective channels between two sources nodes, one relay node and one destination node. At each source node, a phase-precoding scheme that changes the phases of the transmitted symbols is applied. At the relay node, received sources sequences are detected, precoded and combined using the Digital Network Coding (DNC) scheme. The destination node uses both direct received signals and relayed signals to estimate the source sequences. For the detecting scheme at the relay and the destination nodes, we propose to use a linear filtering equalization based on Minimum Mean-Square Error (MMSE) criterion. Simulation results show that the proposed precoding technique enhances the Bit Error Rate (BER) performance compared to the non-precoded system.