Massive Access for 5G and Beyond

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