A low complexity soft-output detection algorithm for 2×2 multiple-input multiple-output multiband-ofdm systems using dual carrier modulation

This paper presents a low complexity soft-output detection algorithm for 2×2 multiple-input multiple-output (MIMO) multiband-orthogonal frequency division multiplexing (MB-OFDM) systems using dual carrier modulation (DCM) or modified DCM (MDCM). By detecting each symbol pair of DCM or MDCM separately, the proposed detection algorithm reduces the complexity of the partial Euclidean distance (PED) calculation and the preprocessing complexity, which is the complexity of QR decomposition and channel ordering. This paper also proposes an efficient candidate list extension method for soft-output MIMO detection by using the calculated PEDs. Because the proposed algorithm has a low complexity and can also be implemented in a fully-pipelined hardware, the proposed algorithm is suitable for MB-OFDM systems requiring high speed hardware. The simulation results of applying the proposed algorithm to 2×2 MIMO MB-OFDM systems using DCM or MDCM show that the performance of the proposed algorithm has near soft-output maximum likelihood detection performance. The hardware complexity of the proposed algorithm is approximately 40% of that of the existing algorithm with similar performance.