此文件为ＭＰＡ消息传递算法的ｍａｔｌａｂ源文件，在ＳＣＭＡ非正交多址的情况下，具有良好的多用户检测的性能。(This file is the matlab source of the MPA messaging algorithm, and has good multiuser detection performance in the case of SCMA non orthogonal multiple access.)