A Lower Bound to Rcomp for the Gaussian Channel with a Uniform Quantizing Demodulator

Consideration is given to a channel using orthogonal modulation, soft decision-uniform quantizing demodulation, and perturbed by additive white Gaussian noise. A lower bound is derived to the Rcomp of this channel. The bound explicity exhibits the dependence upon the degree of quantization and is easily computable. It also indicates that the uniform quantizing demodulation scheme is close to optimum for sufficiently fine quantization.