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：我们研究了多源多址接入（UMA）框架（Polyanskiy，2017）下海量和关键物联网服务的共存问题，在该框架中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引入异构流量：为建模海量物联网服务，每个物联网设备独立生成标准消息（与标准UMA设置一致）；为建模关键物联网服务，我们假设生成所有设备共有的告警消息。该设置需要对错误事件（即漏检和虚警）进行重大重新定义，并假设每次传输尝试中的活跃用户数量随机且未知。针对高斯多址接入信道，我们推导了标准消息和告警消息的漏检概率与虚警概率的随机编码可达性界。利用该界限，我们证明正交网络切片能够在高能效要求下实现海量和关键物联网的共存；相反，非正交网络切片因解码标准消息时告警信号的残留干扰而能量效率低下。