Evaluation of interference due to UWB hot spot on fixed wireless access systems

Ultra Wide Bandwidth (UWB) techniques are getting an increased importance due to their many features such as high bit rates availability, low power consumption and location capabilities. UWB technology enables the development of advanced wireless local area networks providing integrated multimedia services to nomadic users over hot-spot areas. The assessment of the possible interference caused by UWB devices on already existing narrowband and wideband systems is fundamental to ensure not conflicting coexistence and, therefore, the acceptance of UWB technology worldwide. In this paper we analyze coexistence between an indoor UWB system and an outdoor Fixed Wireless Access (FWA) system operating in the 3.5 − 5.0 GHz band. We consider a realistic UWB master/slave system architecture using pulse amplitude modulated spread spectrum signals for multiple access and we evaluate the UWB system interfering power in the FWA band accounting for the UWB power spectrum shape. Both upstream and downstream communication directions are analyzed. We show through computer simulation, that in many practical cases UWB system can coexist with FWA without causing any dangerous interference.