“…First, mMTC requires high throughput to accommodate such a massive number of users. Second, mMTC needs a grant-free (GF) access protocol (e.g., ALOHA) [2], i.e., a decentralized protocol without scheduling spectrum resources by the connected BS, to mitigate signaling overheads caused by such a massive number of users. Third, each user limits the maximum transmission power based on its battery and hardware limitations.…”