Call Admission Control of Machine-to-Machine Communications for satisfying Delay Constraint in LTE-Advanced

As concerns about energy efficiency and conservation grow, smart grid and intelligent transportation systems that consist of a large number of sensors, actuators and controllers have positioned as a crucial infrastructure. In such systems, machine-to-machine (M2M) communications between components make it possible the full automatic control of the systems. M2M communications is different from existing systems in the sense that it involves an enormous number of machine-type-communication (MTC) devices. Also traffic patterns and as well as QoS requirements vary widely depending on applications. LTE-Advanced of 3GPP provides a list of supportive functions to facilitate the M2M communications. To this end, a massive admission control scheme for the M2M communications was proposed. However, it is neither scalable nor adaptive particularly when the transmission interval of a device is relatively longer than its delay constraint. As a result, the call blocking probability under such scenario is much higher than normal cases. In this paper, we propose a method that is free from such limitation. Furthermore it can decrease the computational overhead under the condition that the transmission interval and the delay meet certain conditions. Through a set of simulations, we show the improvement in the call blocking probability when using the proposed method. We also provide the theoretical proofs that the proposed method can satisfy the delay constraint.