Multi-hop D2D networking and resource management scheme for M2M communications over LTE-A systems

Machine-to-Machine (M2M) communications are gaining momentum due to the rapid deployment of smart devices with self-organizing capabilities, able to interact each other without the human operator support. Ultimately, M2M paradigm allows Machine-Type Communication Devices (MTCD) to exchange data in Peer-to-Peer (P2P) mode, avoiding the need of a core network handling end-to-end communication establishment between two machines. To this end, the recent Device-to-Device (D2D) feature, introduced by the Third Generation Partnership Project (3GPP) Release 12, fosters new types of service based on the device proximity concept and helps to offload cellular networks by enabling direct-mode communications among cellular users. Furthermore, D2D is also considered a suitable technology to fully support M2M communications thanks to the reduced power consumption and the hop gain. In this paper we first review crucial aspects of M2M communications and examine major issues involving terminals operating in D2D mode in LTE-A networks. Then, a multi-hop D2D communication scheme is proposed in order to enhance end-to-end connectivity among devices in a proximity area within an LTE-A cell. We also describe a promising resource allocation approach aware of the multi-hop D2D network configuration, able to fulfil bandwidth requests of all the cooperating devices, according to the related role in the network set-up.