Lattice-reduction-aided conditional decoding

We introduce a low-complexity decoder with near-optimal performance for transmission over multi-antenna systems. By using lattice basis reduction for generating almost orthogonal channel matrix, we enhance the conditional decoding technique to implement a fast yet efficient decoder. The lattice-reduction-aided conditional decoder is presented as a general detection technique over fading channels to yield significant savings in complexity while achieving close to Maximum Likelihood (ML) performance. We specifically apply the decoder for two practical schemes, uncoded multi-input multi-output (MIMO) systems and the Golden code. By employing the orthogonality defect factor as a universal measure to select a near-orthogonal channel submatrix for conditional decoding, we implement an almost optimal decoder with linear complexity over quasi-static channels for the Golden code and the four-by-four uncoded MIMO system.