Sub-Granting Radio Resources in Overlay D2D-Based V2V Communications

Abstract Capacity, reliability, and latency are seen as key requirements of new emerging applications, namely Vehicleto- Everthings (V2X) and Machine Type Communication (MTC) in future cellular networks. Device-to-Device (D2D) communication is envisaged to be the enabler to accomplish the requirements for the aforementioned applications. Due to the scarcity of radio resources, hierarchical radio resource allocation, namely the sub-granting scheme, has been considered for the overlay D2D communication. In this paper, we investigate the assignment of un-utilized radio resources to Device-to-Infrastructure (D2I) users, i.e., beneficiary user, for moving users in a dynamic environment. The sub-granting assignment problem is mathematically cast as the uplink cell throughput maximization problem. To this end, two heuristics are proposed: 1) Dedicated Sub-Granting Radio Resource (DSGRR) in a centralized manner, and 2) Open Sub-Granting Radio Resource (OSGRR) in a distributed fashion. Simulation results show improved cell throughput for the OSGRR compared with the DSGRR yet less overhead while having reasonable tightness to the maximum achievable uplink throughput.