Adaptive Threshold for TR Pulse Cluster Systems

Recently, a new transmitted reference (TR) pulse cluster structure was proposed. This new structure contains uniformly and compactly spaced reference and data pulses, and thus enables a simple, robust and practical auto-correlation detector to be used in the receiver. Our previous research showed that inter-pulse interference (IPI) is present in the received TR pulse cluster signal due to the dense multipath UWB channel and this leads to asymmetric error performance when the transmitted bit is "+1" or "-1". In this paper, we propose an adaptive threshold scheme which modifies the decision threshold for a particular channel realization to ensure the equivalent channel is back to binary symmetric. The performance of the TR pulse cluster system hence can be greatly improved. The decision threshold varies from channel to channel. Simulation results show that this new adaptive threshold scheme outperforms the original bipolar system with zero threshold by about 1.7 dB for 802.15.4a channel model 1 and 0.6 dB for channel model 8