Abstract
Machine to machine (M2M) communication is the direct communication between devices without human involvements. Recently M2M services in cellular networks have been promoted by cellular operators for sustainable profits for the next decade. However, M2M will also bring serious access congestion problems into cellular networks. This paper studies random access (RA) protocols for cellular M2M communication systems and in particular investigates two RA methods including transmission probability control and two-hop Aloha as well as their dynamic extensions. Our analysis illustrates that the proposed solutions can provide much better performance in terms of random access throughput and delay.