Prioritized Random Access for Accommodating M2M and H2H Communications in Cellular Networks

In cellular machine-to-machine (M2M) communications, one of the most challenging issues is to accommodate random access (RA) requests of a massive number of machine nodes while not severely degrading the RA performance of human-to-human (H2H) communications. As the number of RA requests from a massive number of machine nodes increases, human nodes may hardly access the network because the current cellular network cannot support the access priority during the RA procedure. In this paper, we propose a prioritized random access (PRA) scheme, which provides a higher access priority to the human nodes in a co-existing environment of both M2M and H2H by differentiating the transmit power of preamble sequences at the first step of the RA procedure. We mathematically analyze the proposed PRA scheme in terms of collision probability and access delay. The performance evaluation shows that the proposed PRA scheme enables the human nodes to achieve much lower collision probabilities and shorter access delays than the machine nodes, while accommodating a massive number of machine nodes.