We develop a new algorithm for activity detection for grant-free multiple access in distributed multiple-input multiple-output (MIMO). The algorithm is a distributed version of the approximate message passing (AMP) based on a soft combination of likelihood ratios computed independently at multiple access points. The underpinning theoretical basis of our algorithm is a new observation that we made about the state evolution in the AMP. Specifically, with a minimum mean-square error denoiser, the state maintains a block-diagonal structure whenever the covariance matrices of the signals have such a structure. We show by numerical examples that the algorithm outperforms competing schemes from the literature.

翻译：我们在分布式多投入多重产出(MIMO)中开发了一种用于检测无赠与性多重访问的活动的新算法。这种算法是一种分布式的大致信息传递(AMP)版本,其基础是多个接入点独立计算的可能性比率的软组合。我们算法的基本理论基础是我们对AMP国家演变情况的新观察。具体地说,只要信号的变量矩阵具有这样的结构,国家就维持一个区块对角结构。我们通过数字实例显示,算法比文献中竞争计划的效果要好。