We investigate the coexistence of massive and critical Internet of Things (IoT) services in the context of the unsourced multiple access (UMA) framework introduced by Polyanskiy (2017), where all users employ a common codebook and the receiver returns an unordered list of decoded codewords. This setup is suitably modified to introduce heterogeneous traffic. Specifically, to model the massive IoT service, a standard message originates independently from each IoT device as in the standard UMA setup. To model the critical IoT service, we assume the generation of alarm messages that are common for all devices. This setup requires a significant redefinition of the error events, i.e., misdetections and false positives. We further assume that the number of active users in each transmission attempt is random and unknown. We derive a random-coding achievability bound on the misdetection and false positive probabilities of both standard and alarm messages on the Gaussian multiple access channel. Using our bound, we demonstrate that orthogonal network slicing enables massive and critical IoT to coexist under the requirement of high energy efficiency. On the contrary, we show that nonorthogonal network slicing is energy inefficient due to the residual interference from the alarm signal when decoding the standard messages.

翻译：研究在Polyanskiy（2017）提出的无源多址接入（UMA）框架中，大规模物联网与关键物联网服务的共存问题，该框架下所有用户使用公共码本，接收端返回解码码字的无序列表。通过适当修改该设置以引入异构流量。具体而言，为模拟大规模物联网服务，每个物联网设备独立生成标准消息（采用标准UMA设置）；为模拟关键物联网服务，则假设生成对所有设备公共的报警消息。该设置需显著重新定义错误事件（即漏检与虚警）。进一步假设每次传输尝试中的活跃用户数量是随机且未知的。我们在高斯多址信道上推导了标准消息与报警消息的漏检概率和虚警概率的随机编码可达性界。基于该界，我们证明正交网络切片能够在高能效要求下实现大规模与关键物联网的共存；相反，非正交网络切片因解码标准消息时报警信号的残余干扰而能效低下。