Improved EXIT Algorithm Based on Gaussian Mixture Model and its Application to LDPC Construction in Coding Cooperative Systems With Hybrid Fading

In this study, an EXIT algorithm based on Gaussian mixture coding and multi-dimensional node information calculation is proposed. The objective is to solve the problem of performance analysis of cooperative communication and LDPC code construction under hybrid fading and impulse noise. First, Gaussian mixture model estimation of the decoding initialization information is performed by the expectation maximized algorithm. In addition, key parameters, such as weight, mean, and variance of the Gaussian mixture model are obtained. Then, the multi-dimensional information processing is performed on the variable node and the check node information in the traditional EXIT algorithm based on the multi-dimensional Gaussian mixture model and system symmetry analysis. Finally, the objective function of LDPC code optimization is constructed, the constraints are given, and the optimal LDPC code degree distribution is obtained by the differential evolution algorithm. The simulation results show that compared with the traditional regular and other irregular LDPC codes, the newly constructed degree distribution has better performance in waterfall characteristics and error floor characteristics. Such distribution provides a necessary method to analyze and optimize the performance of cooperative coding system under hybrid media or hybrid fading.