An Open-Loop Adaptive Algorithm for Dynamic Multipath Estimation in DSSS Systems

In direct sequence spread spectrum systems, the multipath effect (MPE) is known to be one of the most important factors to degrade measurement accuracy. To tackle this problem, we propose a 2-D fast adaptive filtering-based multipath estimation (2D-FAFME) algorithm. A preprocessing is first introduced to compensate the waveform distortion caused by the signal path dynamic. Based on the preprocessing outputs, an optimized adaptive filter is reiteratively designed for each individual range-Doppler cell in the minimum mean-square error sense. Accurate estimates of signal path parameters can be obtained by suppressing the cross-interferences among different paths, and thus the measurement error induced by MPE can be mitigated. An improved 2D-FAFME method is further introduced to reduce the computational complexity and storage memory based on a waveform approximation. The proposed methods have lower computational burden, less storage memory, and better signal-to-noise ratio performance compared with several representative methods. The proposed methods are applicable to complex multipath scenarios, which is verified by simulation results.