A Novel Multipath Mitigation Method Based on Fast Orthogonal Search (FOS) for Short-Delay Multipath with Zero Doppler Shift Difference

Abstract

Multipath is the main factor affecting the positioning accuracy degradation in the Time and Code Division-Orthogonal Frequency Division Multiplexing (TC-OFDM) system. There is no effective mitigation method for short–delay multipath with zero Doppler shift difference in indoors. A novel multipath mitigation method is proposed to solve the problem, which is based on Fast Orthogonal Search (FOS). The candidate functions are created to represent the TC-OFDM reference correlation functions with several multipath delays and amplitudes, and the FOS tries to build a fitting model between the measured correlation functions and the selected candidate functions. Hence, the receiver can obtain accuracy direct and multipath estimations. The theoretical expressions of the proposed method are derived, and the multipath mitigation performances of n-Early Minus Late (nEML), Early Late Slope (ELS), Multipath Estimating Delay Lock Loop (MEDLL) are simulated and compared with the proposed method. The simulation results indicate that the performance of the proposed method is better than the classical techniques under the short-delay multipath scenarios with zero Doppler shift difference.