MMSE interference rejection followed by joint maximum likelihood detection for distributed antenna network

Abstract

In this research minimum mean square error (MMSE) interference rejection is applied to a receiver in a distributed antenna networks (DAN). In the DAN, not only the desired signals, but also the interference signals may reach from nearby antennas. For the overloaded signal situation, non-linear detection schemes such as joint maximum likelihood detection can be applied to the received signals. However, the amount of metric calculations in the joint maximum likelihood detection (MLD) increases exponentially with the number of signal streams. Therefore, MMSE interference rejection followed by a MLD detection is proposed. The effect of residual interference after the MMSE interference rejection is evaluated. Numerical results obtained through computer simulation show that the performance of the proposed scheme is about 2.5 dB worse at a bit error rate (BER) of 10∼3 as compared with that of the joint MLD while the complexity reduces by a factor of 4 for QPSK signal streams. The BER performance degradation can be suppressed to about 1.0 dB by adjusting the value of the coefficient in the MMSE matrix.