Impact of Mistiming on the Achievable Information Rate of Rake Receivers in DS-UWB Systems

TL;DR

This paper analyzes how mistiming affects the achievable information rate of Rake receivers in DS-UWB systems, revealing that performance loss depends on bandwidth and multipath diversity, with implications for receiver design.

Contribution

It derives a generalized expression for performance degradation due to mistiming and compares different Rake receiver schemes under mistiming conditions.

Findings

Performance loss varies with bandwidth and multipath diversity.

MRC S-Rake suffers the largest performance loss under mistiming.

Performance degradation is less related to target achievable information rate.

Abstract

In this paper, we investigate the impact of mistiming on the performance of Rake receivers in direct-sequence ultra-wideband (DS-UWB) systems from the perspective of the achievable information rate. A generalized expression for the performance degradation due to mistiming is derived. Monte Carlo simulations based on this expression are then conducted, which demonstrate that the performance loss has little relationship with the target achievable information rate, but varies significantly with the system bandwidth and the multipath diversity order, which reflects design trade-offs among the system timing requirement, the bandwidth and the implementation complexity. In addition, the performance degradations of Rake receivers with different multipath component selection schemes and combining techniques are compared. Among these receivers, the widely used maximal ratio combining (MRC) selective-Rake (S-Rake) suffers the largest performance loss in the presence of mistiming.