Non-binary LDPC Coded Modulation And Its Application

In recent years,there has been a very fast development of mobile communication technology.The 4G(Fourth Generation)technology has been taken into large scale industrial and business applications.More-over,the 5G(Fifth Generation)related technology also has been widely studied in both academia and industry.In 2016,3GPP(3rd Generation Partnership Project)adopted the LDPC(Low-density parity-check)codes as one of the channel coding schemes in 5G technology standards,The LDPC codes will be applied for the mobile communication broadband data services with moderate to long coding block?Due to the high-speed and the ultra-reliable transmission requirements,the shortage of spectrum is a long term and server challenge for the future deployment of 5G platforms.To improve the spectral efficiency,high-order modulation will be naturally taken into account.The performance loss caused by high-order modulation can be adequately compensated by powerfull coding schemes.NBLDPC(Nonbinary Low-density parity-check)codes as the evolution of the binary LDPC codes defined over larger finite fields,have been gradually noticed by many scholars.NBLDPC coded high-order modulation is an efficient coded modulation scheme.With the devel-opment of 5G technology,it will become a focus of future research.Firstly,We briefly describe LDPC codes,including BLDPC codes and NBLDPC codes coding,and EXIT(Extrinsic information transfer charts)analysis.Based on the NBLDPC codes,the M-PSK(Phase Shift Keying)and M-QAM(Quadrature amplitude modulation)high-order modulation are discussed.M-PSK itself has a constant envelope advantage,it is suitable for microwave channels and satellite communication channels and other non-linear situation.But at the same time when the order of modulation is rising,the constellation of the same radius of the constellation point density is too high,the bit error rate will deteriorate sharply.In this thesis,M-PSK modulation constellation based on NBLDPC codes is designed to optimize the performance of bit error rate.The scheme is as follows:the M-PSK constellation points are grouped based on the concept of the distance between and in each group.Then,we can sacrifice the distance in each group and expanding the distance between groups.On the one hand,because the number of points in each group is small,although the distance is small,we still can effectively compensate the bit error rate by the excellent performance of NBLDPC codes.On the other hand,because of the expansion of distance between groups,the overall performance of the decoding can be improved.This thesis proposes a hybrid symbol mapping scheme in order to deal with the combination between high-order modulation and NBLDPC codes.This scheme is a kind of interleaving mapping method which can be applied to any order of LDPC codes combined with any order of high-order modulation.For a given order of GF(2P)LDPC codes and 2q-order high-order modulated signals,we propose a bit interleaving scheme.The bit error rate upper bound of each bit of the modulation symbol is calculated by the 2q high-order modulation constellation map given in the actual situation,so as to form the interleaving.In addition,the quantization threshold of EXIT can be used to efficiently analyze the mapping scheme under different multi-domain code joint modulation system scenarios.Through the threshold numerical analysis and the simulation results,the following conclusion can be drawn:The hybrid symbol mapping scheme presented in this thesis shows better decoding performance and applicability compared with the traditional design scheme.This thesis also analysis the performance of the hybrid symbol mapping scheme proposed in the MIMO(Multi-Input Multi-Output)system,including SIMO(Single-Input Multiple-Output)system based on MRC(Maximum Ratio Combining),and MIMO system based on MMSE(Minimum mean square error).In the case of different channels,a series of simulation results are compared by some representative schemes.The simulation results show that the proposed scheme has a good practical value.