Closed-Form Upper Bounds for the Constellation-Constrained Capacity of Ultra-Wideband Communications

This paper focuses on the evaluation of performance limits for ultra-wideband communications in terms of constellation-constrained capacity. The major drawback of most of the existing capacity measures is that an exact and closed-form expression cannot be easily obtained. As a result, evaluation of these capacity measures must resort to numerical methods. In this paper, however, closed-form upper bounds for the constellation-constrained capacity of PPM modulation are proposed for both coherent and non-coherent receivers. The tightness of the proposed bounds is evaluated under the IEEE 802.15.3a/4 channel models where a good match is observed, in particular, for the low-SNR regime.