Relay-aided Random Access for Energy-Limited Devices in the IoT

In the Internet-of-Things (IoT), random access is employed for devices to share a common access channel in packet transmission with low signaling overhead. Although a retransmission strategy is necessary for packet collision resolution, it might be prohibitive for some devices due to energy and complexity constraints. In this paper, we consider a novel relay-aided random access (RARA) scheme where re-transmissions are carried out by relay nodes, not devices. Thanks to multipacket reception with multiple copies of collided signals forwarded by relay nodes, a receiver is able to recover multiple collided packets simultaneously in RARA. As a result, devices of limited complexity and energy source can enjoy reliable transmission using RARA, and the throughput can approach 1 with a large number of relay nodes.