MMSE multipath diversity combining for multi-access TH-UWB in the presence of NBI

The performance of asynchronous time-hopping ultra-wideband (TH-UWB) multiple access spread spectrum is analytically investigated in a UWB realistic multipath channel and in the presence of narrowband interference (NBI). In particular, an interference suppression receiver for TH-UWB wireless systems is proposed. It consists of selecting the first strongest multipath components using an appropriate Rake receiver with the path diversity combining being based on the minimum mean square error criterion. Pulse position modulation and pulse amplitude modulation schemes are considered. The expressions of the signal-to-interference and noise ratio at the output of the selective Rake combiner, the system multi-access data rate as well as the conditional bit error rate are also derived. The impact of different parameters, such as the number of selected dominant paths, the NBI power as well as the time hopping sequence code on the system performance are studied. Results reveal that the proposed receiver can almost completely eliminate the effect of NBI.