Source-channel coding strategies: tandem coding vs. channel-optimized quantization

Two source-channel coding strategies, tandem coding and channel-optimized quantization, are compared on the basis of distortion vs. complexity. For each, formulas for the mean-squared error and complexity used to minimize distortion subject to a complexity constraint. The results suggest there is a threshold such that tandem coding is better than channel-optimized quantization when and only when the complexity constraint is larger than the threshold.