Coded Cooperation Based On LDPC Convolutional Codes

With the popularization of various intelligent terminals,the proposed concepts of smart city and intelligent transportation,as well as the rapid development of the Internet,unmanned aerial vehicles(UAV)and other industries,the transmission rate and capacity of the mobile communication network put forward higher requirements,making the current 4G communication network facing tremendous pressure.In order to ensure the high reliability of the mobile network,get faster transmission rate and greater system capacity,the 5G communication system has attracted much attention.One of the characteristics of 5G communication system is to realize the ultra-high speed transmission,from the perspective of the physical layer technology security,the use of as much as possible high-gain channel coding,and the implementation of collaborative transmission between users is an inevitable trend.Cooperative communication allows multiuser generate a virtual MIMO system by sharing their antennas to achieve the spatial diversity,and then applying the mature coding technology to the cooperative scheme to further enhance the system performance.The application of mature technology in collaborative encoding scheme,can further enhance the system performance.In this treatise,we study the cooperative communication based on the advanced coding technology.In this treatise,Low Density Parity Check Code(LDPC),which can approach the Shannon limit and has low encoding and decoding complexity,is adopted as the channel coding technology.LDPC convolutional codes is a kind of LDPC block code,which combines the good performance of convolutional code and LDPC block code.Therefore,the basic principle of LDPC block codes and the construction of parity check matrix are introduced.On this basics,the parity check matrix of LDPC convolutional codes is constructed by matrix transformation.The encoding and decoding of LDPC convolutional codes and the factors affecting their performance are discussed.Secondly,three main cooperative communication methods are introduced,which are amplify and forward,decode and forward,and coded cooperation.We focus on the principle and characteristics of the coded cooperation.Thirdly,according to the parity check matrix of the LDPC convolutional codes,separating the mother codes created by LDPC convolutional codes into two parts through puncturing,users and his partner collaboratively transfer different parts of the coded words in two frames,achieving the diversity gain and coding gain without increasing the transmission power and bandwidth.Finally,as we know,traditional coded cooperation can achieve great diversity gains in slow fading,but will not bring any added benefit in fast fading.For this problem,in this paper,we propose a space-time coding scheme based on LDPC convolutional codes,that is,introducing the technology of space-time code into the second frame transmission of the coded cooperation,makes the scheme can be widely used in a variety of scenarios,combat fast and slow fading generally.Simulation results show that the performance of LDPC convolutional codes improved greatly in the framework of coding cooperation.Especially,the space-time coding based on LDPC convolutional codes can significantly improve the performance of the system both in fast and slow fading scenarios.The application scenario is more flexible and the application range is more widely.