Spatial Group Based Access Class Barring for Massive Access in M2M Communications

In this letter, a novel spatial group based access class barring (ACB) scheme is proposed for machine-to-machine (M2M) random access system with timing advance (TA) assisted machine-type devices (MTDs) identification and preamble reuse. Specifically, multiple ACB factors are assigned for groups to provide precise access control, and an optimization problem of determining the optimal ACB factors which maximize the throughput is formulated. To reduce the computational complexity, the optimal problem is further simplified to get a suboptimal solution. The performance advantages of the proposed scheme are verified by simulations.