Unleashing latency-critical IIoT communication by virtue of cooperative sidelink-assisted DL transmissions

Fifth generation wireless networks will play a crucial role in the digitization of factories. Smart factories demand ultra-reliable low-latency communication (URLLC) services to ensure a defect-free uninterrupted production system. In our earlier work, we have proposed a sidelink-assisted cooperative retransmission scheme, in which the neighbouring user equipments (UEs) assist an error-prone downlink (DL) transmission. The scheme benefits from making use of multiple independently fading device-to-device (D2D) links, and yields significant improvements in reliability, as analysed in our prior work. In this paper, we extend our study further to investigate latency for a realistic industrial IoT (IIoT) scenario modeled in a system-level evaluation platform. The D2D links established between communication nodes distributed over the factory area enable a reliable transmission by attaining larger Signal-to-Interference-Noise Ratio (SINR), yielding lower probability for higher latencies and reduced number of retransmissions. Our evaluations show that the cooperative scheme allows to save one retransmission for attaining 99.999% reliability and significantly reduces the queueing delays, thanks to a better usage of resources. The system-level evaluation proves our scheme to be an efficient tool to guarantee the reliability and latency requirements of URLLC in IIoT communication for smart factories at reasonable costs in resources.