Research On Depolarization Effect Cross Polarization Discrimation And Polarization Mode Dispersion Estimation Algoritm For Wireless Channel

Polarization information processing technology has a lot of ad-vantages.It can improv the polarization isolation.It is not sensitive to phase noise and not influenced by the non-linearity of the power amplifier.Hence,it has drawn more and more attention in the field of wireless communications.However,the polarization state of the signal during the transmission of the wireless channel is affected by the depolarization ef-fect of the channel,and the performance of the system adopting the po-larization information processing technology is reduced.Obtaining the information of depolarization effect from the channel state information and then using the compensation method to reduce the influence of the depolarization effect on the polarization state of the signal is the basis and key to improve the performance of the polarization information pro-cessing technology.Therefore,it is necessary to study the method of es-timating the depolarization effect.The task of this paper is from the national major projects for science:"Research on power amplifier energy efficience based on cognitive and polarization signal processing(61271177)" and "Research on polarimet-ric self-interference cancellation in full-duplex system based on additive Gaussianized phase noise(61501050)".In this paper,the depolarization effect of XPD and PMD in wireless channel are estimated and divided into two research cases.For flat fading channels,the estimation of depo-larization effect XPD is mainly considered.Cross polarization discrimi-nation estimation algorithm based on iterative scaled least squares is proposed.For frequency-selective fading channel,we mainly consider the estimation of depolarization effect of PMD,and propose a polarization mode dispersion estimation algorithm based on selection combining.The main work of this paper is following three aspects:(1)This paper summarizes and analyzes the related theory of depo-larization effect and the current research status.It points out that the cur-rent researches on depolarization effect mainly focus on how to use or compensate the depolarization effect under the condition that the depo-larization effect of the channel is known.They don not study how to es-timate it.At the same time,this paper also summarizes and organizes the common pilot-based channel estimation algorithm and multipath delay estimation algorithm.This paper analyzes its application scenario and ap-plies it to depolarization effect XPD and PMD estimation.(2)Aimed at the depolarization effect XPD estimation.This paper proposes a XPD estimation algorithm based on iterative scaled least squares under the dual-polarized flat fading channel model.The algorithm is mainly divided into two steps:Firstly,we use a scaling factor on the basis of least-squares(LS)and iterative method to reduce estimation error of channel coefficients.Secondly,we get channel correlation matrix by multiplying the channel matrix and its transpose.Since XPD is a parameter of channel correlation matrix,we can get XPD from it.Simulation show that the proposed algorithm have better estimated performance and the same time complexity compared with LS.What is more,along with the number of iterations,the estimated performance of proposed algorithm is close to MMSE.(3)Aimed at the depolarization effect PMD estimation.This paper proposes a polarization mode dispersion estimation algorithm based on selection combining under the dual-polarized frequency-selective fading channel model.Firstly,to improve the accuracy of estimation,we use selection combining at the receiver,which choose signals having higher signal noise ratio(SNR)from horizontal and vertical component.Then,We use selected signals to estimate multipath delay.Secondly,we compute PMD directly by using delay spread and max delay which can be calculated from multipath delay.Simulation show that the proposed algorithm has better estimation performance compared with PMD estimation algorithm using single component.In order to accurately estimate the channel depolarization effect.In this paper,the depolarization effect XPD and PMD estimation algorithms are studied.According to the different channel types,cross polarization discrimination estimation algorithm based on iterative scaled least squares and polarization mode dispersion estimation algorithm based on selection combining are proposed respectively.The results show that the proposed algorithm can accurately estimate XPD and PMD,which provides a new idea for studying the estimation of depolarization effect.