Stability Analysis Of Timing Acquisition Methods With Multi-hypothesis In Indoor UWB Multipath And MAI Channel

The paper analyzes the effect of timing acquisition methods with multi-hypothesis on the UWB system performance, including the BER and user number tolerance, in the multi- path and multiuser channel environment. To our knowledge, it is the first time to investigate the stability problem about multi-hypothesis timing acquisition schemes. In the multi- path UWB systems, the multi-hypothesis timing acquisition strategy has been considered as the most effective method, which takes advantage of the indoor multipath propagation characteristics and considers more than one hypothesized phase as a good estimate of the true signal phase. That means there exists a multipath set where any a path can be locked on by the receiver. The strategy can contribute to speeding up the timing acquisition process through some efficient search approaches at the cost of timing accuracy. However, it is sure that the relative delay between the locked non-strongest path and the strongest one will have the effect on the system performance. In the paper, we have analyzed the effect of the different relative path delay on the BER and user number tolerance for DS-UWB systems employing the different PN sequences. Numerical results show that both the relative path delay and the cross-correlation performance of the PN sequence can degrade the performance of DS-UWB systems.