Research On IR-UWB Multiuser Detection

Ultra-wideband (UWB) is a recent technology which develops very fast. It has drawn considerable attention in wireless communication, network, radar, imaging and location, and is becoming one of the most competitive candidates for its possibility of extremely high data rates, low power consumption, security, and excellent performance in anti-multipath ability, etc.With the development of UWB, large quantity of UWB products will be used for rapid voice and data communication in indoor environments. Multiple-access interference plays an essential role in communication quality. Multi-user detection is not only necessary but also important for reliable communication. In this thesis, based on the elementary characteristic of signaling structure of a UWB signal, multi-user detection for Impulse Radio UWB (IR-UWB) in both AWGN channel and IEEE 802.15.3a CM1 channel are studied:Firstly, optimal multiuser detection in AWGN channels is studied. The optimal receiver that optimizes the decisions of all users by jointly estimating the sequence of bits chooses the information symbols that maximize the posterior log-likelihood. However, complexity grows exponentially with the number of users.Secondly, linear receivers in AWGN channels are discussed, including BR receiver, quasi-decorrelator receiver and quasi-MMSE receiver. Due to the signaling structure of an IR-UWB signal, the three methods can provide considerable performance with low complexity.Finally, SIC (Successive Interference Cancellation) receiver for line-of-sight UWB channels is studied. In SIC, error propagation will occur which reduces the BER performance of latter stages. An improved SIC algorithm is employed, which converges sequence estimation algorithm, and obtains a low complexity detector with quite good performance. Comparative performance simulation with respect to SIC shows that the improved SIC outperforms SIC for all users.