Analysis of UWB system capacity in a realistic multipath environment with coexistence constraints

Ultra-wideband (UWB) wireless technology is envisaged to play a key role in B3G wireless systems, guaranteeing very high bit rates, low power consumption, low costs and location capabilities. The availability of low cost and efficient devices makes UWB technology very competitive on the communications market. However, its worldwide acceptance mainly relies on coexistence issues because of the necessity of sharing the spectrum with other radio systems. The reduction, due to coexistence constraints, in the capacity of an UWB system in a realistic multipath channel is investigated. Link performance of an UWB system that exploits either partial or selective Rake combining at the receiver is evaluated over experimental impulse responses of an UWB indoor channel in an office building. Using these results, system performances are evaluated through a semi-analytical procedure in terms of outage probability and system capacity. Results on system capacity account for the limitations imposed by the current regulation, leading us to introduce the concept of `UWB systems limited by coexistence'.