Pilot assisted multi-user UWB communications

In this paper, we study the use of sub-carrier pilots for multi-carrier ultra wideband (MC-UWB) systems. In particular, we introduce a simple receiver structure for sub-carrier pilot assisted ultra wideband orthogonal frequency division multiplexing (SPA-UWB-OFDM) system. The new system exploits the high time resolution of the UWB-OFDM signal to simplify the implementation of the full multipath diversity receivers. We show that any sub-carrier can be used to estimate the delays and complex amplitudes of the channel. Furthermore we show that if some of sub-carriers are modulated with training data, a generalized maximum likelihood ratio test (GMLRT) can be used to simultaneously estimate the channel and decode the transmitted information. The demodulation is done by correlating the information bearing sub-carriers with the pilot sub-carriers. Furthermore, we show that multi-user detection can be achieved by using different pilot sub-carriers for different users.