A Novel Method for DOA and Time Delay Joint Estimation in Multipath OFDM Environment

Xiangzhi Li,Weijia Cui,Bin Ba,Haiyun Xu,Yankui Zhang

doi:10.1155/2020/3952175

Xiangzhi Li, Weijia Cui + Show 3 more

Open Access

https://doi.org/10.1155/2020/3952175

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Abstract

Joint time delay and direction of arrival estimation based on uniform linear arrays in Orthogonal Frequency Division Multiplexing (OFDM) systems has to face the problems posed by coherent multipath environments and high computational complexity. In this paper, a novel fast method is proposed to achieve a joint direction-of-arrival (DOA) and time-dealy (TD) estimation of multipath OFDM signals by fully using space-frequency characteristics. Firstly, we construct an extended virtual array by combining the array structure and frequency-domain information. Then, we calculate the extended channel frequency response matrix and adopt smoothing processing to eliminate the multipath effect. Next, we get the result of DOA estimation by using a closed-form solution, which costs little complexity and can achieve fast estimation. Finally, we conduct a one-dimensional spectral search using the obtained DOA values to estimate time delays. Simulation results show that our proposed methods have excellent performance even under low SNR conditions in different multipath environments. Furthermore, methods proposed in this paper have much less computational complexity and better estimation performance compared with the multidimensional spectral peak search methods.

Highlights

Introduction e technology of Orthogonal FrequencyDivision Multiplexing (OFDM) is one of the Multi-Carrier Modulation (MCM) technologies with low implementation complexity and high bandwidth efficiency [1]
Researchers have proposed various super-resolution algorithms for parameter estimation. e multiple signal classification (MUSIC) algorithm for time delay estimation based on narrowband signals is proposed in [7]
References [10, 11] use the compressive sensing method to conduct the estimation in underdetermined conditions. When it comes to direction of arrival (DOA) estimation, the multiple signal classification (MUSIC) algorithm [12] and rootMUSIC [13] have been developed and widely used. e researchers of [14] propose a space-time conversion MUSIC (STC-MUSIC) algorithm for DOA estimation

Summary

Signal Model

A uniform linear array (ULA) is adopted in this paper, which is composed of M sensors. E uniformly distributed subcarriers have something similar to the array sensors of the ULA in the channel frequency-domain response, which is called space-time equivalence. By constructing the extended frequency-domain response, the dimension of virtual bandwidth is expanded by M time from L to ML. Smoothing processing is one of the effective methods used to solve the parameter estimation problem of coherent signals. Based on the closed-form estimation of DOA we have obtained using the TLS-ESPRIT method, we can estimate time delays of the signals by one-dimensional (1D) search, where τp could be obtained by. (i) Establish the received signal model and get the extended channel frequency-domain response H. (ii) For coherent signals, use the smoothing processing method and construct the covariance matrix using (19). When multipath signals are independent, we use an improved searching method expressed as (33), estimating time delay

Analysis of Computational Complexity

Simulation Analysis

Findings

Conclusions