This paper investigates the issue of cooperative activity detection for grant-free random access in the sixth-generation (6G) cell-free wireless networks with sourced and unsourced paradigms. First, we propose a cooperative framework for solving the problem of device activity detection in sourced random access. In particular, multiple access points (APs) cooperatively detect the device activity via exchanging low-dimensional intermediate information with their neighbors. This is enabled by the proposed covariance-based algorithm via exploiting both the sparsity-promoting and similarity-promoting terms of the device state vectors among neighboring APs. A decentralized approximate separating approach is introduced based on the forward-backward splitting strategy for addressing the formulated problem. Then, the proposed activity detection algorithm is adopted as a decoder of cooperative unsourced random access, where the multiple APs cooperatively detect the list of transmitted messages regardless of the identity of the transmitting devices. Finally, we provide sufficient conditions on the step sizes that ensure the convergence of the proposed algorithm in the sense of Bregman divergence. Simulation results show that the proposed algorithm is efficient for addressing both sourced and unsourced massive random access problems, while requires a shorter signature sequence and accommodates a significantly larger number of active devices with a reasonable antenna array size, compared with the state-of-art algorithms.

中文翻译：

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合作活动检测：源和无源大规模随机访问范例

本文研究了第六代（6G）无源无线网络中无源随机访问的合作活动检测问题。首先，我们提出了一个合作框架来解决源随机访问中设备活动检测的问题。特别是，多个接入点（AP）通过与邻居之间交换低维中间信息来协同检测设备活动。提议的基于协方差的算法通过利用相邻AP之间的设备状态向量的稀疏性促进和相似性促进项来实现这一点。基于前向后分离策略，提出了一种分散式近似分离方法，以解决所提出的问题。然后，所提出的活动检测算法被用作协作无源随机访问的解码器，其中多个AP协同检测传输消息的列表，而与传输设备的身份无关。最后，我们在步长上提供了充分的条件，以确保所提出算法在Bregman散度意义上的收敛性。仿真结果表明，与现有技术相比，该算法可有效解决源和无源大规模随机访问问题，同时需要更短的签名序列，并以合理的天线阵列尺寸容纳大量有源设备。算法。无论传输设备的身份如何，多个AP协同检测传输的消息列表。最后，我们在步长上提供了充分的条件，以确保所提出算法在Bregman散度意义上的收敛性。仿真结果表明，与现有技术相比，该算法可有效解决源和无源大规模随机访问问题，同时需要更短的签名序列，并以合理的天线阵列尺寸容纳大量有源设备。算法。无论传输设备的身份如何，多个AP协同检测传输的消息列表。最后，我们在步长上提供了充分的条件，以确保所提出算法在Bregman散度意义上的收敛性。仿真结果表明，与现有技术相比，该算法可有效解决源和无源大规模随机访问问题，同时需要较短的签名序列，并以合理的天线阵列尺寸容纳大量有源设备。算法。