Research On Multi-stream Signal Transmission Theory And Scheme Based On The Generalized Polarization Transform

Polar codes are the first constructive code family achieving the channel capacity,which is one of popular research directions in the coding theory.In the 2015 IEEE Symposium on Information Theory(IEEE ISIT),the inventor of polar code Prof.Ankan has pointed out that for the future de-velopment of polar coding,the whole communication system optimization based on the channel polarization idea and the polar code application will become the mainstream directions.However,the design and optimization of wireless transmission system based on polarization transform theory is still lacking of the well-established framework.The research considering the feature of fading channel,the MIMO signal space mapping and the multiuser codebook design has a long way to go.On this account,this thesis extends the design idea of binary polar cod?ing to the polarization transmission of communication signal,and we call this as "generalized polarization transform".We focus on the multi-stream signal transmission theory and practical applications research.This thesis starts with the generalized polarization phenomena commonly existing in wireless communication systems so that we extend the core design idea of polar codes to the whole processing of communication systems.In sight of the multi-stream signal transmission scenario,this thesis establish the the-oretical framework of multi-stream signal polarization transmission based on the generalized polarization transform.By this way,it promotes this new research direction.Specifically,this thesis includes the following four aspects of innovative work.1)The thesis accomplishes the error evaluation and optimization de-sign for the polar code mainstream Gaussian approximation construction algorithm.First,we make the error analysis for the widely-used Gaussian approximation(GA)polar code construction algorithm.By calculating two types of error set and the upper bound of cumulative-logarithmic error,we show the inherent reason that the conventional GA algorithm leads to the severe performance loss at the long code length or the low code rate.Com-bining the above analysis,the thesis further proposes the design criteria of the GA approximation functions for the polar code construction.It can not only ensure the high accuracy but also reduce the computational com-plexity.Simulation results indicate that the GA algorithms designed in this thesis can guarantee the excellent performance of polar codes at various extreme code length and code rate configurations.2)This thesis makes the research and design for the efficient non-orthogonal multiple access(NOMA)multiuser detection algorithms.Note that NOMA is one of the typical multi-stream signal transmission scenar-ios.This thesis considers the new NOMA techniques used in the 5G.In sight of the high complexity and poor performance problems in the NOMA multiuser detection,we design a group of high performance and low com-plexity NOMA multiuser detection algorithms.First,based on the "fast message exchange" idea in the LDPC decoding,this thesis optimizes the message exchange mechanism in the NOMA message passing algorithm(MPA)multiuser detection.We propose two types of enhanced MPA so that the algorithm convergence speed is improved and the computational complexity is reduced.Then,the thesis combines the multiuser detector and the channel decoder so as to propose a damping factor(DF)aided it-erative multiuser receiver.The DF value is optimized by using the EXIT chart.Simulation results indicate that with the DF,the iterative multiuser receiver can quickly converge to the theoretically optimal performance so that it enhance the multiuser detection reliability.3)On the basis of the above two works,this thesis designs the Polar-NOMA system followed by the generalized polarization theory.First,we deeply excavate the signal polarization phenomenon in the multiuser da-ta stream non-orthogonal superposition,and combine this with the signal modulation and binary polar coding so as to form the "user?signal?bit"three stage generalized polarization transform framework.On this account,the binary polar coding and NOMA transmission are integrated into an uni-fied theoretical framework so as to make the joint design.Then,this thesis proposes two types of user partition scheme.The first type is sequential user partition(SUP).This scheme origins from the chain rule in mutual information,and there is no capacity loss in the user partition process so that SUP can provide the highest spectrum efficiency.The other scheme is parallel user partition(PUP).This scheme brings capacity loss in the user partition process while it improves the system parallelism.For the SUP,this thesis designs the polar scheduling strategy to determine the user parti-tion order.By this means,the system polarization gain is maximized so that the system performance is improved.Simulation results show that the pro-posed Polar-NOMA system can outperform the widely-used Turbo-NOMA iterative system.In addition,the larger the system overloading factor is,the more obvious the performance gain becomes.4)The thesis designs the Polar-MIMO system based on the generalized polarization theory.First,we view the MIMO transmission as a special kind of polarization transform in the signal domain.By using the mutual information chain rule,the original MIMO channel is split to a group of dependent memory less channels.Combining the modulation and binary polar coding,it forms the "antenna?modulation?bit"three stage gener-alized polarization transform structure.In this sight,the channel coding,modulation and the MIMO transmission are integrated into an unified the-oretical framework to make the joint design.Then,we propose two types of antenna partition scheme.For the sequential antenna partition(SAP),its corresponding Polar-MIMO systems can be strictly proved to achieve the system capacity and provide the optimal performance.The other scheme is parallel antenna partition(PAP),it trades the system performance loss for the parallelism gain.In the practical Polar-MIMO signal transmission pro-cess,this thesis combines different MIMO detection algorithms to design the code construction scheme,where the fading channel is approximated by an AWGN channel with identical capacity.Simulation results indicate that the proposed Polar-MIMO system can outperform the conventional Turbo/LDPC-MIMO systems under the equivalent or lower complexity.