Statistical QoS Analysis of Reconfigurable Intelligent Surface-Assisted D2D Communication

This work analyzes statistically the Rician block-fading reconfigurable intelligent surface (RIS)-assisted D2D link where the transmit node runs under delay QoS constraints. First, we implement mode selection for the D2D link whereby the D2D pair may either transmit data from RISs directly via a base station (BS) or straight-forwardly. We next present closed-form formulas for the RIS-assisted D2D link’s effective capacity (EC). The transmit D2D node uses a fixed rate rt unless channel state information at the transmitter (CSIT) is available; in such case, it communicates with the variable rate rt(n); adjustable according to the channel conditions. It enables us to simulate the RIS-assisted D2D link in both scenarios as a Markov system. We also consider D2D settings underlay and overlay. We employ the HARQ retransmission scheme and provide the EC analysis of the HARQ-enabled RIS-assisted D2D link to raise the throughput of the RIS-assisted D2D link when CSIT is unknown.