Thesis On Space-Time Coding for Large Antenna Arrays

Multiple-input multiple-output (MIMO) systems can greatly improve the capacity and performance of wireless communications. In particular, space-time coding techniques have received much attention in recent years as an efficient approach to achieving the performance gains offered by MIMO channels. Thus far, most work on space-time coding has focused on systems with small antenna arrays or high signal-to-noise ratios (SNRs), for which it has been shown that codes should be designed according to the rank and determinant criteria. For such scenarios, coherent space-time coding and differential space-time modulation (DSTM) schemes have been designed, for systems with or without channel knowledge at the receiver, respectively. In recent years, there has been some work on coherent space-time coding for large arrays, which indicates that the code design metric should be chosen diffently from that for small arrays. In this dissertation, we study the design of space-time coding for large arrays. We focus on three aspects: performance analysis, code construction and decoding algorithms. We first analyze the asymptotic performance of differential space-time modulation. A new upper bound on the pairwise-error probability is derived for large arrays. This bound suggests that Euclidean distance is an appropriate design criterion for DSTM with large numbers of antennas, which is similar to the design of coherent space-time coding for the large-array regime. For two transmit antennas and four or more receive antennas, we use the new design criterion to obtain several new unitary codes with large minimum Euclidean distance. The proposed codes outperform some existing codes, for example, the well-known Alamouti code, for large receive arrays.

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