Performance Comparison of Low-Complexity Detection Schemes for V-BLAST Coded MIMO-OFDM

The combination of vertical Bell Laboratories layered space-time (V-BLAST) and orthogonal frequency division multiplexing (OFDM) is a promising solution for realizing spectral efficient transmission in scattered environments and overcoming the frequency-selective fading in broadband radio channels. The Exhaustive Detection of V-BLAST OFDM, which applies the same detection on individual subcarriers, can lead to satisfying performance at the cost of complexity. In addressing the complexity issue, two low-complexity detection schemes [8][9] are proposed. Both of them are based on the subcarrier grouping and apply the same detection order to the whole group. The nulling vectors are calculated by Gram-Schmidt Orthonormalization (GSO) of the channel matrix at individual subcarriers. We compare the performance of these two detection schemes for 4x4 and 6x6 system. Compared with Exhaustive Detection, both low-complexity detection schemes can significantly reduce the complexity with marginal performance penalty. The scheme [8] has even lower complexity than the scheme [9]. For a 6x6 system, the scheme [8] can reduce 91.3% complexity with only l.OdB performance loss.