Low-Complexity QRD-M with Path Eliminations in MIMO-OFDM Systems

The QR decomposition-M algorithm (QRD-M) is a popular signal detector which has similar error performance with maximum likelihood (ML) in multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) systems. The QRD-M uses M candidates at each layer, unlike the ML. However, the complexity of the QRD-M is high in huge MIMO-OFDM systems due to unnecessary survival paths at each layer. In this paper, a low-complexity QRD-M with variable number of survival paths at each layer is proposed. In the conventional QRD-M, path eliminations at the previous layer reduce the number of calculations for accumulated squared Euclidean distance (ASED) in subsequent layers. The proposed QRD-M eliminates unnecessary survival paths by comparing the ASED and the calculated threshold at each layer. The simulation results show that the proposed QRD-M maintains the error performance for the conventional QRD-M and has a very low complexity.