Trellis code-aided high-rate differential space-time block code and enhanced uncoded space-time labeling diversity.

Abstract

In this dissertation, a trellis code-aided bandwidth efficiency improvement technique for space-time block coded wireless communication systems is investigated. The application of the trellis code-aided bandwidth efficiency improvement technique to differential space-time block codes (DSTBC) results in a high-rate system called trellis code-aided DSTBC (TC-DSTBC). Such a system has not been investigated in open literature to date. Hence, in this dissertation, the mathematical models and design methodology for TC-DSTBC are presented. The two transmit antenna TC-DSTBC system transmits data by using a transmission matrix similar to the conventional DSTBC. The fundamental idea of TC-DSTBC is to use a dynamic mapping rule rather than a fixed one to map additional bits onto the expanded space-time block code (STBC) prior to differential encoding, hence, the additional bits-to-STBC mapping technique, which incorporates trellis coding is proposed for square M-ary quadrature amplitude modulation (M-QAM) in order to enhance the bandwidth efficiency without sacrificing the error performance of the conventional DSTBC. The comparison of bandwidth efficiency between TC-DSTBC and the conventional DSTBC show that TC-DSTBC achieves a minimum of 12.5% and 8.3% increase in bandwidth efficiency for 16-QAM and 64-QAM, respectively. Furthermore, the Monte Carlo simulation results show that, at high signal-to-noise ratios (SNR), the four receive antenna TC- DSTBC retains the bit error rate (BER) performance of the conventional DSTBC with the same number of receive antennas under the same independent and identically distributed (i.i.d.) Rayleigh frequency-flat fading channel and additive white noise (AWGN) conditions for various square M-QAM modulation orders and numbers of additional bits. Motivated by the bandwidth efficiency advantage of TC-DSTBC over the conventional DSTBC, the trellis code-aided bandwidth efficiency improvement technique is extended to the recently developed uncoded space-time labeling diversity (USTLD) system, where a new system referred to as enhanced uncoded space-time labeling diversity (E-USTLD) is proposed. In addition to this, a tight closed form lower-bound is derived to predict the average BER of the E-USTLD system over i.i.d. Rayleigh frequency-flat fading channels at high SNR. The Monte Carlo simulation results validate that the more bandwidth efficient four receive antenna E-USTLD system at the minimum retains the BER performance of the conventional four receive antenna USTLD system under the same fading channel and AWGN conditions for various square M-QAM modulation orders. The bandwidth efficiency improvement for TC-DSTBC and E-USTLD is achieved at the cost of a much higher computational complexity at the receiver due to use of the high-complexity Viterbi algorithm (VA)-based detector. Therefore, the low-complexity (LC) near-maximum-likelihood (near-ML) detection scheme proposed for the conventional USTLD is extended to the E-USTLD detector in order to reduce the magnitude of increase in the computational complexity. The Monte Carlo simulation results show that E-USTLD with a VA-based detector that implements LC near-ML detection attains near optimal BER performance.