Performance of reduced computation trellis decoders for mobile radio with frequency selective fading

Reduced computation trellis decoding algorithms are compared to the Viterbi algorithm for use in digital mobile radio receivers in which the signal is affected by frequency selective fading. The channel is modeled as a transversal filter with time-varying tap weights. Quadrature phase-shift keying (QPSK) and minimum-shift keying (MSK) signals are considered, and a novel fractionally spaced receiver is introduced for bandlimited signals. Simulations are used to compare the receiver complexity and error performance of suboptimum receivers implemented using either the T algorithm or the M algorithm with receivers based on the Viterbi algorithm. The reduced computation trellis decoding algorithms are shown to be a practical method for combating frequency-selective fading