Multiuser Interference Mitigation in DS-UWB Ranging System

A simplified large sample maximum likelihood (SLSML) algorithm is presented for estimating Time of Arrival (TOA) in the multiuser direct-sequence ultra-wideband (DSUWB) system. Due to approximating the TOA as the integer multiples of the chip duration, using the integrate-and-dump filter in chip sampling rate rather than matched filter makes a substantial reduction of complexity and easing the requirement of sampling rate of LSML algorithm. The proposed estimator extends the LSML to the dense multipath channel furthermore. With the long pulse repetition property of DS-UWB ranging system, the complexity of SLSML has little increase in multipath channel than that of AWGN channel. Numerical evaluations under AWGN channel and IEEE 802.15.4a channel model show that SLSML algorithm is robust against near-far problem and has little performance degradation even when system is fully loaded.