An Improved QRD-M Detection Algorithm for MIMO Communication System

QR decomposition based M-algorithm (QRD-M) can provide near maximum likelihood detection (MLD) performance and low complexity for MIMO communication. The QRD-M algorithm reduces the complexity by selecting M candidates with the smallest accumulated metrics at each level of the tree search. The trade-off between performance and complexity can be adjusted only by setting the parameter M which cannot provide more valuable tradeoff options with better performance to complexity ratio. Based on the equivalent QRD-M model, a new detection scheme is proposed in this paper for MIMO system on flat fading channel. The detection scheme, named as improved QRD-M (IQRD-M) with two independent parameters, is composed of two parts. After performing QR decomposition of the channel matrix, the MLD with length P is done, the accumulated metrics are calculated and sorted, which gives an ordered set, then IQRD-M algorithm is used to search the left layers with novel termination methods. The proposed algorithm provides better tradeoff options and more near-ML performance with low complexity.