Research On Multiuser Detection Techniques For Underwater Acoustic Communication Based On Variable Tap Length

In recent years,underwater acoustic communication technology has drawn considerable attention in both academia and industry because of the increasing development of marine economy and the burgeoning requirement in many commercial and military applications.However,with the characteristics of complex multipath propagation,enormous propagation delay and limited bandwidth,the stochastic ocean channel brought great challenges to achieve reliable multi-user underwater acoustic communication.In order to improve the link reliability,cooperative communication technology is used in multiuser user underwater acoustic communication,and the characteristics of underwater acoustic channel are studied.The main contents of this paper are as follows:Firstly,the multiuser underwater acoustic communication system model is established,and the characteristics of underwater acoustic channel are analyzed.The BELLHOP model is used to establish the underwater acoustic channel.The fixed tap-length multi-user detection is studied based on IDMA iterative multiuser detection.Secondly,aiming at the influence of tap-length on the multi-user detection performance and the computational complexity,the variable tap-length multi-user detection scheme for non-cooperative model is proposed.The proposed detector can adaptively adjust the tap-length in accordance with the specific underwater acoustic channel profile by using the tap-length update algorithm,thereby improving system performance.Introducing cooperative communication technology,the multiuser user communication system model is set up.Considering the influence of the combining methods and the tap-length,a joint adaptive combining and variable tap-length(JACVT)multiuser detection scheme is proposed.Simulation analysis verifies the feasibility and effectiveness of the JACVT multiuser detection scheme.Finally,considering the utilization ratio of spectrum resources,co-frequency and co-time full duplex(CCFD)is introduced,non-cooperative multi-user underwater acoustic communication system model based on self-interference cancellation is established.Aiming at the problem of self-interference in the system,the influence of step size factor and filter order on the self-interference cancellation performance is analyzed.Considering the self-interference(SI),multiple access interference(MAI)and inter-symbol interference(ISI)cancellation,a joint self-interference cancellation and variable tap-length(SIC-VT)multi-user detection scheme based on variable step and variable order is proposed.At the same time,a joint adaptive combining and variable tap-length multiuser detection scheme(SIC-JACVT)based on self-interference cancellation is proposed under the full-duplex cooperative model to further improve the system performance.The influencing factors,the performance advantages of variable step and variable order multi-user detection scheme are analyzed by the simulation results.