Hybrid ORA and NORA schemes for machine‐to‐machine communication in long‐term evolution networks

Abstract

Massive machine-type communication (MTC) devices will be deployed in the fifth-generation wireless communication networks, which will inevitably result in access collision problems. To alleviate this issue, the authors propose a hybrid orthogonal random access (ORA) and non-orthogonal random access (NORA) scheme to improve the throughput. In the proposed scheme, an expanded physical random access channel is employed to transmit preambles and MTC devices identity information simultaneously, which can help the base station (BS) to determine whether the MTC device can successfully transmit preamble. Subsequently, the MTC devices whose transmitted preambles are detected successfully by BS are statistically grouped, and then the devices in the same group transmit their data messages in a non-orthogonal multiple access manner. Meanwhile, to further improve the access throughput, the MTC devices that did not pass access class barring check are permitted to compete for the remained unscheduled resources with orthogonal multiple access manner. They also analyse the access throughput of the proposed scheme. Simulation results show that to serve all MTC devices distributed in a cell, their proposed scheme outperforms the traditional multichannel ALOHA and two-stage random access scheme in terms of access throughput and required number of random access slots.