Polar Coded Modulation

The arrival of the 5th generation Mobile Communication era is accompanied by more diverse wireless network requirements.In order to keep pace with the increasingly commercial and intelligent process of 5G,it is urgent to further improve the reliability of data transmission,utilize the spectrum resources more efficiently,and support more terminal devices to access the communication network.Traditional method of designing and optimizing coding and modulation separately is difficult to meet the challenges brought by 5G,while the combination of coding and modulation can improve reliability and expand transmission capacity,thereby solving the problem of scarce spectrum resources.Among many codes,polar code stands out due to its excellent performance and has been adopted as the communication standard for 5G control channels.Therefore,it has attracted widespread attention,at the same time there is still much space for exploration in the field of polar coded modulation.This thesis focuses on polar coded modulation,and proposes a polar coded superposition modulation scheme.The combination of channel coding and constellation shaping is able to approach the Shannon limit.The problem of energy loss caused by the uniform distribution of constellation points in Gaussian channel is solved.The structure of polar coded superposition modulation at the transmitting side and the energy allocation algorithm between layers are discussed.A joint demapping-decoding algorithm is proposed,and the SCAN(Soft Cancellation)decoding algorithm of polar code is simplified by combining the characteristics of the frozen bit patterns.Simulations show that polar coded superposition modulation can obtain relatively good performance under the condition that the total energy of the transmitting side is limited,and it is applicable in the Gaussian channel.At the same time,polar code and sparse code multiple access system(SCMA)have broad application prospects in 5G access network.SCMA combines high-dimensional modulation with sparse spread spectrum,in order to superimpose and transmit multi-user signals in the same subcarrier,which is a special kind of superposition modulation.SCMA codebook presets the user's superposition modulation mode,therefore,this thesis studies the SCMA codebook,analyzes the defects of the existing codebook and improves the mapping relationship,therefore obtains better performance.The joint coding and modulation techniques of polar code and SCMA is mainly studied.Two joint coded modulation models of polar code and SCMA are introduced,which are bit interleaved polar coded SCMA and multilevel polar coded SCMA.The applicable polar code construction and decoding algorithm are given,and the performance is evaluated by simulation.