A research study submitted in partial fulfillment of the requirement for the degree of Master of Engineering, School of Engineering and Technology

Research Studies Project Report (M. Eng.) - Asian Institute of Technology, 1995

In this research study an investigation into a low-complexity Soft-Output Viterbi Equalization (SOVE) is made. The algorithm delivers M-ary reliability information for each detected symbol. The reliability information value is calculated by using Bayes' theorem. Two solutions oflow-complexity SOVE named one-dimensional Vertical update SOVE (V-SOVE) and one-dimensional Horizontal update SOVE (H-SOVE) are presented and applied at the cost of suboptimality. The quality of the soft-outputs produced from the V-SOVE and H-SOVE is evaluated in terms of Bit Error Rate (BER). The performance of the system using the V-SOVE and the H-SOVE is simulated by use of computer simulation. The Typical Urban channel specified by GSM standards and the n/4- shifted Differential Quadrature Phase Shift Keying (DQPSK) modulation method are used in the simulation model. Perfect knowledge of the channel coefficients are assumed in the simulation work. Comparisons between the performance of the V-SOVE, the H-SOVE and the classical Viterbi Equalizer (VE) are made.