Outage evaluation of ultra wideband spread spectrum system with RAKE combining in lognormal fading multipath channels

Ultra wideband (UWB) spread spectrum system capacity is studied. User capacity is evaluated analytically against the conditional outage criterion. The probability of outage varies depending on the multipath channel intensity profile, severity of shadowing, signal-to-interference ratio target, number of users, timing errors, and the number of fingers combined in the RAKE receiver. The sum of lognormally distributed signals is mainly modelled by a Fenton-Wilkinson approximation. Numerical results show that the outage performance is quite sensitive to the variation of several key parameters.