The conformal array can make full use of the aperture,save space,meet the requirements of aerodynamics,and is sensitive to polarization information.It has broad application prospects in military,aerospace,and communic...The conformal array can make full use of the aperture,save space,meet the requirements of aerodynamics,and is sensitive to polarization information.It has broad application prospects in military,aerospace,and communication fields.The joint polarization and direction-of-arrival(DOA)estimation based on the conformal array and the theoretical analysis of its parameter estimation performance are the key factors to promote the engineering application of the conformal array.To solve these problems,this paper establishes the wave field signal model of the conformal array.Then,for the case of a single target,the cost function of the maximum likelihood(ML)estimator is rewritten with Rayleigh quotient from a problem of maximizing the ratio of quadratic forms into those of minimizing quadratic forms.On this basis,rapid parameter estimation is achieved with the idea of manifold separation technology(MST).Compared with the modified variable projection(MVP)algorithm,it reduces the computational complexity and improves the parameter estimation performance.Meanwhile,the MST is used to solve the partial derivative of the steering vector.Then,the theoretical performance of ML,the multiple signal classification(MUSIC)estimator and Cramer-Rao bound(CRB)based on the conformal array are derived respectively,which provides theoretical foundation for the engineering application of the conformal array.Finally,the simulation experiment verifies the effectiveness of the proposed method.展开更多
A blind adaptive scheme is proposed for joint maximum likelihood (ML) channel estimation and data detection of singleinput multiple-output (SIMO) systems. The joint ML optimisation over channel and data is decompo...A blind adaptive scheme is proposed for joint maximum likelihood (ML) channel estimation and data detection of singleinput multiple-output (SIMO) systems. The joint ML optimisation over channel and data is decomposed into an iterative optimisation loop. An efficient global optimisation algorithm called the repeated weighted boosting search is employed at the upper level to optimally identify the unknown SIMO channel model, and the Viterbi algorithm is used at the lower level to produce the maximum likelihood sequence estimation of the unknown data sequence. A simulation example is used to demonstrate the effectiveness of this joint ML optimisation scheme for blind adaptive SIMO systems.展开更多
The frequency offset and channel gain estimation problem for multiple-input multiple-output(MIMO)systems in the case of flat-fading channels is addressed.Based on the multiple signal classification(MUSIC)and the maxim...The frequency offset and channel gain estimation problem for multiple-input multiple-output(MIMO)systems in the case of flat-fading channels is addressed.Based on the multiple signal classification(MUSIC)and the maximum likelihood(ML)methods,a new joint estimation algorithm of frequency offsets and channel gains is proposed.The new algorithm has three steps.A subset of frequency offsets is first estimated with the MUSIC algorithm.All frequency offsets in the subset are then identified with the ML method.Finally,channel gains are calculated with the ML estimator.The algorithm is a one-dimensional search scheme and therefore greatly decreases the complexity of joint ML estimation,which is essentially a multi-dimensional search scheme.展开更多
The generalized maximum likelihood(GML)algorithm for direction-of-arrival estimation is proposed.Firstly,a new data model is established based on generalized steering vectors and generalized array manifold matrix.The ...The generalized maximum likelihood(GML)algorithm for direction-of-arrival estimation is proposed.Firstly,a new data model is established based on generalized steering vectors and generalized array manifold matrix.The GML algorithm is then formulated in detail.It is flexible in the sense that the arriving sources may be a mixture of multiclusters of coherent sources,the array geometry is unrestricted,and the number of sources resolved can be larger than the number of sensors.Secondly,the comparison between the GML algorithm and the conventional deterministic maximum likelihood(DML)algorithm is presented based on their respective geometrical interpretation.Subsequently,the estimation consistency of GML is proved,and the estimation variance of GML is derived.It is concluded that the performance of the GML algorithm coincides with that of the DML algorithm in the incoherent sources’case,while it improves greatly in the coherent source case.By using genetic algorithm,GML is realized,and the simulation results illustrate its improved performance compared with DML,especially in the case of multiclusters of coherent sources.展开更多
基金the National Natural Science Foundation of China(62071144,61971159,61871149).
文摘The conformal array can make full use of the aperture,save space,meet the requirements of aerodynamics,and is sensitive to polarization information.It has broad application prospects in military,aerospace,and communication fields.The joint polarization and direction-of-arrival(DOA)estimation based on the conformal array and the theoretical analysis of its parameter estimation performance are the key factors to promote the engineering application of the conformal array.To solve these problems,this paper establishes the wave field signal model of the conformal array.Then,for the case of a single target,the cost function of the maximum likelihood(ML)estimator is rewritten with Rayleigh quotient from a problem of maximizing the ratio of quadratic forms into those of minimizing quadratic forms.On this basis,rapid parameter estimation is achieved with the idea of manifold separation technology(MST).Compared with the modified variable projection(MVP)algorithm,it reduces the computational complexity and improves the parameter estimation performance.Meanwhile,the MST is used to solve the partial derivative of the steering vector.Then,the theoretical performance of ML,the multiple signal classification(MUSIC)estimator and Cramer-Rao bound(CRB)based on the conformal array are derived respectively,which provides theoretical foundation for the engineering application of the conformal array.Finally,the simulation experiment verifies the effectiveness of the proposed method.
文摘A blind adaptive scheme is proposed for joint maximum likelihood (ML) channel estimation and data detection of singleinput multiple-output (SIMO) systems. The joint ML optimisation over channel and data is decomposed into an iterative optimisation loop. An efficient global optimisation algorithm called the repeated weighted boosting search is employed at the upper level to optimally identify the unknown SIMO channel model, and the Viterbi algorithm is used at the lower level to produce the maximum likelihood sequence estimation of the unknown data sequence. A simulation example is used to demonstrate the effectiveness of this joint ML optimisation scheme for blind adaptive SIMO systems.
基金supported by the National Science Fund for Distinguished Young Scholars (No.60725105)the National Basic Research Program of China (No.2009CB320404)+4 种基金the National Natural Science Foundation of China (Grant No.60572146)The Research Fund for the Doctoral Program of Higher Education (No.20050701007)the Fund of Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institute of Chinathe Key Project of Science and Technologies Research of MOE (No.107103)the 111 Project (B08038).
文摘The frequency offset and channel gain estimation problem for multiple-input multiple-output(MIMO)systems in the case of flat-fading channels is addressed.Based on the multiple signal classification(MUSIC)and the maximum likelihood(ML)methods,a new joint estimation algorithm of frequency offsets and channel gains is proposed.The new algorithm has three steps.A subset of frequency offsets is first estimated with the MUSIC algorithm.All frequency offsets in the subset are then identified with the ML method.Finally,channel gains are calculated with the ML estimator.The algorithm is a one-dimensional search scheme and therefore greatly decreases the complexity of joint ML estimation,which is essentially a multi-dimensional search scheme.
基金supported by the National Natural Science Foundation of China (No.60272370)the Teaching and Research Award Program for Outstanding Young Teachers in high education institutes of Ministry of Education,China (TRAPOYT).
文摘The generalized maximum likelihood(GML)algorithm for direction-of-arrival estimation is proposed.Firstly,a new data model is established based on generalized steering vectors and generalized array manifold matrix.The GML algorithm is then formulated in detail.It is flexible in the sense that the arriving sources may be a mixture of multiclusters of coherent sources,the array geometry is unrestricted,and the number of sources resolved can be larger than the number of sensors.Secondly,the comparison between the GML algorithm and the conventional deterministic maximum likelihood(DML)algorithm is presented based on their respective geometrical interpretation.Subsequently,the estimation consistency of GML is proved,and the estimation variance of GML is derived.It is concluded that the performance of the GML algorithm coincides with that of the DML algorithm in the incoherent sources’case,while it improves greatly in the coherent source case.By using genetic algorithm,GML is realized,and the simulation results illustrate its improved performance compared with DML,especially in the case of multiclusters of coherent sources.