The Internet of Things (IoT) has been extensively investigated as an enabling technology for improving our daily life. With increasing demands for seamless connectivity, the space-air-ground integrated network (SAGIN) is expected to provide reliable communications for IoT devices anywhere and anytime. Since IoT devices have sparse activity and low signaling overhead, random access can be an efficient means to relieve the burden of machine-type communication, which provides connections among massive IoT devices. However, there are a few drawbacks. For example, random access suffers from signal collisions, and low-energy IoT devices may have limited transmission coverage. To overcome these drawbacks, in this article, relay-aided random access (RRA) is proposed as a promising strategy to support massive IoT devices in the SAGIN. We first introduce the RRA structure and scheme as well as several advantages over conventional random access. Then we present some of the key technologies of RRA, including energy harvesting, arrival time detection, and signal number detection. Finally, different scenarios or use cases for practical applications of RRA schemes in the SAGIN are discussed.

中文翻译：

---

空空地面综合网络中的中继辅助随机访问

物联网（IoT）已被广泛研究为改善我们日常生活的辅助技术。随着无缝连接需求的增长，空空地面集成网络（SAGIN）有望在任何时间，任何地点为IoT设备提供可靠的通信。由于物联网设备活动稀少且信令开销低，因此随机访问可以减轻机器类型通信的负担，这是在大型物联网设备之间提供连接的有效方法。但是，有一些缺点。例如，随机访问会遭受信号冲突，并且低能耗物联网设备的传输覆盖范围可能有限。为了克服这些缺点，本文提出了中继辅助随机访问（RRA）作为在SAGIN中支持大型IoT设备的有前途的策略。我们首先介绍RRA结构和方案，以及相对于常规随机访问的一些优点。然后，我们介绍了RRA的一些关键技术，包括能量收集，到达时间检测和信号编号检测。最后，讨论了SAGIN中RRA方案实际应用的不同场景或用例。