Channel estimation in underwater acoustic communication

Abstract

In this thesis, we propose a simplified and accurate channel and carrier frequency offset~(CFO) estimation method for underwater multiple-input multiple-output~(MIMO)-orthogonal frequency division multiplexing~(OFDM) systems. We estimate the CFO based on a constant modulus by minimizing a cost function, and estimate channel using the matching pursuit~(MP) algorithm. The performance of the proposed method is proven by computer simulation using two sets of transmitters and receivers, each with 128 sub-carriers. We prove that the proposed method has better performance and a lower complexity compared to the least square~(LS) algorithm. Moreover, the accuracy of the channel estimation with and without CFO estimation will be compared. These tests suggest that channel estimation using MP and CFO estimation with CM signaling is simple and accurate, and has a low complexity for underwater MIMO-OFDM system.

Also, we propose a channel estimation algorithm based on angle domain for the MIMO-OFDM system in underwater acoustic communication~(UAC). We assumed the system model which is modeled by a tap-delay line~(TDL) with angle bin. The proposed algorithm consist of 2 stages - non-zero tap selection and finding the channel plane. The orthogonal matching pursuits~(OMP) algorithm is used to estimate the tap and the channel plane. We compare the 2-stage algorithm with a existing method about complexity and accuracy. Also, we uses the dantzig selector (DS),convex optimization a comparison group.