Joint Reservation and Contention-Based Access for URLLC-Enabled D2D Communications

This letter investigates the ultra-reliable and low-latency link allocation for device-to-device (D2D) communications in face of sporadic packet arrivals. Specifically, contention-based access scheme has been widely used to achieve low-latency transmission, where the users can randomly access the pre-reserved resource pool without resource scheduling. However, considering the inconsistent packet arrivals and heterogeneous spatial distribution of D2D pairs (DPs), some DPs who are closely located or have more frequent packet arrivals are more likely to suffer collisions, which seriously deteriorates their reliability performance. In this context, the resource reservation can well offset the weaknesses of contention-based access scheme by reserving dedicated links to these DPs. Then, the hybrid link allocation issue is formulated as the optimization problem which aims to minimize the sum packet error probability under the low latency constraint. Moreover, an exact potential game model and a blocking-pair based best response algorithm are proposed. Simulation results verify the superiority of the proposed hybrid link allocation scheme.