Time-Out Lattice Sequential Decoding for the MIMO ARQ Channel

The optimal diversity-multiplexing-delay tradeoff for the multi- input multi-output (MIMO) automatic repeat request (ARQ) channel can be achieved using an incremental redundancy lattice space- time codes. The optimal tradeoff has been shown in to be achieved using a list lattice decoder for joint detection and decoding. However, such decoder suffers from high computational complexity for low-to-moderate signal-to-noise ratios, especially for large signal´s dimension. In this paper, we would like to construct a more efficient decoder that is capable of achieving the optimal tradeoff with much lower complexity. We show, analytically and via simulation, that using a modified lattice sequential decoder for joint error detection and correction in the MIMO ARQ channel, the optimal tradeoff can be achieved with significant reduction in decoder complexity at a very small degradation in performance.