Improved performance measures for space-time coding with applications to code design.

摘要

Capacity of wireless communication systems can be greatly increased by employing multiple transmit and/or receive antennas. Space-time coding has become an attractive approach to achieve reliable communications in multiple antenna systems. Current space-time code design criteria in the literature do not completely characterize the system parameter of interest, i.e., frame or bit error probability. In this dissertation, we develop new analytical tools for space-time coded systems.; Traditional space-time code design techniques mainly focus on minimizing the worst case pairwise error probability. However, worst case pairwise error probability does not completely characterize the frame error performance. To this end, we consider the truncated union bounds on frame and bit error probabilities of space-time trellis codes in quasi-static fading channels. Truncated union bound is a function of the “distance spectrum” of the code. We propose a computationally efficient algorithm to compute the distance spectrum of space-time trellis codes achieving maximal diversity gain. This algorithm utilizes a state reduction technique that identifies the minimal complexity error state diagram. Numerical results illustrate that distance spectrum analysis provides accurate characterization of the relative performance of space-time codes, making it attractive as a computationally efficient tool in optimal space-time code design.; The design criteria for optimal space-time codes depend largely on the number of receive antennas. It is therefore desirable to develop a systematic design approach that yields codes with satisfactory performance in various scenarios. We present a new upper bound on the probability of error which captures the dependence of the design criteria on the number of receive antennas. We utilize the new bound to analyze the optimality and performance trends of a linear space-time block code construction. The numerical results demonstrate that the new upper bound provides an accurate characterization of the code performance for various levels of receive diversity. We further present a computationally efficient approach for constructing space-time trellis codes which exhibit satisfactory performance in various scenarios. Simulation results demonstrate the near-optimal performance of the new trellis codes with different numbers of receive antennas.