Performance Measures of a UWB Multiple-Access System: DS/CDMA versus TH/PPM

Time-hopping combined with pulse position modulation has been the original proposal for ultra-wideband systems. Spread spectrum techniques for multiple access and interference suppression are being considered for ultra-wideband radio systems. A digital impulse radio receiver using direct-sequence spreading is proposed in the paper and the signal processing scheme is investigated. Performance measures, such as error rate, multi-user capability, and system data rate for the proposed receiver structure, are derived mathematically and compared with the impulse receiver deploying time-hopping. The direct-sequence format is shown to support more active users; i.e, provide multi-access communications at a lower biterror rate. Upper bounds for the number of permissible active users and the system data rate are derived analytically.