Research On Wireless Channel Estimation And Detection Technology Based On Non-orthogonal Structure

With the developing of new radio access technology,the available spectrum resources for new communication requirement become more and more limited thus increasingly precious.At the same time,with the explosive growth of the number of users,the future mobile communication technology needs to meet the needs of extremely increased number of access links.Therefore,the future mobile communication system requires not only high systemic capacity but also high user-wise spectrum efficiency.Under this background,the non-orthogonal transmission structure,including non-orthogonal pilot design and non-orthogonal multiple access system design attract more and more interest of researcher in recent years.In this paper,the channel estimation and its optimal design algorithm of non-orthogonal pilot structures are studied in terms of the improvement of spectrum utilization of the system.In terms of non-orthogonal multiple access systems,the channel estimation and frequency offset estimation algorithm of non-orthogonal multiple access systems are studied.Specific work of this thesis can be summarized as follows:Firstly,the research status of pilot design and non-orthogonal multiple access technology is analyzed,and the channel estimation algorithm is summarized.Secondly,three pilot design schemes of traditional orthogonal pilot design pattern,partial orthogonal pilot design pattern and data superposition pilot design pattern are introduced respectively,and their mutual correlation is simulated and analyzed.Then the non-orthogonal multiple access system are introduced,including interleaver-division multiple access-orthogonal frequency dvision multiplexing(IDMA-OFDM)system,the detection algorithm are introduced,the theoretical derivation and numerical simulation analysis of the achievable rate of the data superposition pilot channel estimation algorithm are given.Then,the channel estimation and detection algorithm of non-orthogonal data superposition pilot is studied and simulated.Moreover,in order to solve the problem of large error of initial channel estimation,this paper proposes two optimization design algorithms based on the interference minimization,pilot selection and interleaver selection.The optimization algorithm based on pilot selection is to select the pilot sequence according to the sent data information to reduce interference,while the optimization algorithm based on interleaver selection is to select the interleaver according to the sent pilot sequence to reduce interference.Next,in order to improve channel estimation accuracy for non-orthogonal multiple access systems,this paper proposes a data-assisted channel estimation algorithm,which updates the estimated channel information aided by the reliability of the coded information.Simulation results proves that the proposed algorithm can improves the performance of tracking the channel changes compared to the conventional channel estimation methods.At the same time,in order to solve the carrier frequency offset problem of OFDM,this paper proposes a joint estimation algorithm of channel and frequency deviation,which uses the orthogonality of orthogonal pilot sequence and the relation of received pilot signal in frequency domain to estimate the carrier frequency offset and channel information of different users.Finally,we summarizes the content of the whole paper and gives the future research direction according to the existing shortcomings.