Massive access, also known as massive connectivity or massive machine-type communication (mMTC), is one of the main use cases of the fifth-generation (5G) and beyond 5G (B5G) wireless networks. A typical application of massive access is the cellular Internet of Things (IoT). Different from conventional human-type communication, massive access aims at realizing efficient and reliable communications for a massive number of IoT devices. Hence, the main characteristics of massive access include low power, massive connectivity, and broad coverage, which require new concepts, theories, and paradigms for the design of next-generation cellular networks. This paper presents a comprehensive survey of aspects of massive access design for B5G wireless networks. Specifically, we provide a detailed review of massive access from the perspectives of theory, protocols, techniques, coverage, energy, and security. Furthermore, several future research directions and challenges are identified.

中文翻译：

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5G 及以后的大规模接入

大规模访问，也称为大规模连接或大规模机器类型通信 (mMTC)，是第五代 (5G) 及 5G (B5G) 无线网络的主要用例之一。大规模接入的典型应用是蜂窝物联网 (IoT)。与传统的人机通信不同，海量接入旨在为海量的物联网设备实现高效可靠的通信。因此，大规模接入的主要特征包括低功耗、大规模连接和广泛覆盖，这需要新的概念、理论和范式来设计下一代蜂窝网络。本文对 B5G 无线网络的大规模接入设计方面进行了全面调查。具体来说，我们从理论的角度对海量访问进行了详细的回顾，协议、技术、覆盖范围、能源和安全。此外，还确定了几个未来的研究方向和挑战。