Joint power allocation and MMSE equalizer designs for MIMO distributed relay networks

Abstract

In this paper, we jointly investigate the power allocation and the equalizer weights for multiple relay nodes in a distributed relay network where each node is equipped with multiple antennas. Based on the minimum mean-square error (MSE) criterion and under the total equalizer power constraint, multi-input multi-output (MIMO) equalizers are designed for equalizing-and-forwarding the signals from the source to the destination in the time domain. An iterative algorithm is proposed to obtain the optimal solution by using the Karush-Kuhn-Tucker (K.K.T.) conditions. With these optimal MIMO equalizers, the MIMO distributed relay network can effectively mitigate the inter-symbol interference (ISI) and achieve both the spatial and multipath diversity gains. Simulation results show that the proposed scheme outperforms the conventional one-tap equalizer scheme for MIMO distributed relay systems in terms of the bit error rate (BER) performance.