P-persistent massive random access mechanism for machine type communication

Growing demand for the Internet of Things (IoT) applications including smart cities, healthcare systems, smart grids, and transportation systems, has enhanced the popularity of Machine-Type Communication (MTC) in 5G and 6G cellular networks significantly. Massive access is a well-known challenge in MTC that should be efficiently managed. In this paper, a grant-based massive access mechanism is introduced where time-frames are separated into two distinct parts; one for contention-based resource granting and the other for scheduled data transmission. In the contention period, we propose a novel random access mechanism where the nodes are grouped based on their distances from the Base Station (BS), and the access probability of each group member is adjusted through solving an optimization problem. In the proposed mechanism, energy efficiency, spectrum efficiency and access delay are formulated in terms of the access probability of devices using p-persistent CSMA method. Thereafter, some optimization problems are formulated to improve the energy/spectrum efficiency and access delay by adjusting the access probability of devices while regarding their delay requirements. The simulation results indicate that the proposed method is better than the previous ones considering energy efficiency, access delay, bandwidth efficiency, and scalability. Also, in the proposed method, delay-sensitive nodes experience lower access delay.