An enhanced random access mechanism for Smart Grid M2M communications in WiMAX networks

Random access is being considered as one of the key bottlenecks for supporting machine-to-machine (M2M) communications over an IEEE 802.16-based WiMAX network. Apart from handling massive access attempts from a large number of devices, the random access plane requires service differentiation capability to meet the diverse QoS requirements of various M2M applications. To address these issues, in this paper, we propose an enhanced random access scheme, where the fixed/low-mobility M2M devices pre-equalize their random access codes using the estimated frequency response of the slowly-varying wireless channel. Consequently, the base station is able to detect a large number of codes as their mutual orthogonality remains preserved. Moreover, a differentiated random access strategy is proposed to provide QoS-aware access service to various M2M devices. The performance of the proposed scheme is demonstrated under two different code matrices using both theoretical analysis and simulation results.