Abstract: A modified detection algorithm for the V-BLAST (Vertical Bell Labs Layered Space-Time) system is presented. The reveived signal vector is feedforward filtered by QR factorization of the sorted channel matrix. The ranked layers are divided into serveral groups. The layers within the same group are detected using the maximum likelihood (ML) algorithm while the decision feedback interference cancellation are performed between groups. Based on the assumption of QPSK modulation and the quasi-static flat fading channel, simulations are made to testify the performance of the proposed algorithm. Results show that the algorithm outperforms the original V-BLAST and ML-DFE(Maximum Likelihood-Decision Feedback Equalization) algorithm dramatically in bit error ratio (BER) performance. Specifically, signal-to-noise ratio (SNR) improvement of 1.6~2.8dB is obtained for BER of 10^-2, while maintaining a reasonable complexity.

Key words: Multi-Input Multi-Output, V-BLAST, maximum likelihood detection