Performance analysis of DS-UWB multiple access under imperfect power control

Ultra-wideband (UWB) technology is characterized by transmitting extremely short duration radio impulses. To improve its multiple-access (MA) capability, UWB technology can be combined with traditional spread-spectrum techniques. So far, much of the research has focused on perfect power-control conditions and on employing time-hopping spread-spectrum with impulse radio using pulse-position modulated signals. In this letter, we outline the attractive features of direct-sequence (DS) UWB MA systems employing antipodal signaling and compare it with time hopping. Performance of DS-UWB communication systems, in terms of MA capability and bit-error rate performance, are evaluated under both perfect and imperfect power-control conditions. An upper bound on the total combined bit-transmission rate is derived.