Dynamic Allocation of RACH Resource for Clustered M2M Communications in LTE Networks

In this paper, we propose a dynamic allocation scheme of random access channel (RACH) resource for clustered machine-to-machine (M2M) communications, in which delay-sensitive services coexist with delay-tolerant ones. Our scheme aims at alleviating the overload and congestion of machine-type (MTC) communication as well as satisfying both delay-sensitive and delay-tolerant services. Specifically, the operation of our protocol includes three aspects. First, in order to make full use of the preamble resources controlled by the Enhanced Node B (eNB), our proposed scheme adopts a two-cluster networking, where MTC devices are divided into two clusters based on their requirements on delay. Second, we develop the dynamic allocation scheme to partition the available preambles for each cluster under the condition of guaranteeing the preferable number of successful devices. Third, the devices belonging to different clusters adopt the access class barring (ACB) mechanism respectively. Simulation results show that our proposed scheme realizes the remarkable increase in improving the access success probability and achieve performance improvement in reducing access delay.