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：我们研究了在海量与关键物联网（IoT）服务共存场景下，Polyanskiy（2017）提出的无源多址接入（UMA）框架中的应用问题。在该框架中，所有用户采用通用码本，接收端返回解码码字的无序列表。我们对这一设置进行适当修改以引入异构流量。具体而言，为建模海量IoT服务，每个IoT设备独立生成标准消息（与标准UMA设置一致）；为建模关键IoT服务，则假设生成所有设备共有的告警消息。这一设置要求对错误事件（即漏检和误报）进行显著重新定义。我们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。在高斯多址信道上，我们推导了标准消息和告警消息的漏检概率与误报概率的随机编码可达性界。基于该界，我们证明了正交网络切片可在高能效需求下实现海量与关键IoT的共存。相反，我们表明非正交网络切片由于解码标准消息时告警信号的残留干扰而能量效率低下。