Performance of trellis-coded direct-sequence spread spectrum with noncoherent reception in a fading environment

In this paper, we consider the performance of different coding schemes for direct-sequence spread spectrum (DS-SS) in a nonselective Rician faded channel. The Nordstrom-Robinson (NR) code, a nonlinear code that has a large distance for a given rate combined with a trellis code, is examined. A bound is developed on the error probability for this trellis-coded NR (TCNR) code with noncoherent reception over a frequency-nonselective Rayleigh or Rician fading channel with additive white Gaussian noise (AWGN). This bound is tighter than the standard union bound. Our results indicate that the standard union bound can be significantly different from the more accurate results obtained from the improved union bound. In addition, there is a considerable coding gain at high signal-to-noise ratio (SNR) for the TCNR code over the conventional DS-SS code at the same data rate