Efficient device-to-device association and data aggregation in industrial IoT systems

Internet of things (IoT) encompass a plethora of connected smart devices and support diverse applications. IoT is likely to be an integral feature of next generation cellular systems. In the manufacturing and supply chain industry, the Industrial IoT (IIoT), which consists of sensors, actuators and machinery, is deployed for monitoring, data collection and analysis, asset management, maintenance planning, and plant control and optimization. In this work, we consider the uplink transmission of an IIoT system, in which the IoT devices transmit their data to the Base Station (BS) through User Equipments (UEs). The BS, in turn, transmits the data to the cloud for further processing. The UEs receive the data from the IoT devices, aggregate with their uplink data, and transmit the aggregated data to the BS. Our investigation shows that the IoT devices require less transmit energy when UEs are used as relays. We study the system when the IoT devices associate themselves with the UEs through the fixed, random, and greedy schemes, and evaluate the end-to-end outage probability at the devices for each of the three schemes. We show that the greedy association scheme has the minimum outage probability at the IoT device. We study the effect of the number of IoT devices, the number of UEs, the data arrival rates at the IoT devices, and the uplink data evolution process of UEs on the outage probability, and draw meaningful insights into IIoT system design.