Multi-Graph Based Spectrum Sharing Scheme in Vehicular Network with Integration of Heterogenous Spectrum.

With the development of autonomous driving technology, the shortage and inefficient utilization of spectrum resource is difficult to support gigabit-per-second data rate vehicle-to-vehicle (V2V) communications. Meanwhile, the latency and reliability requirements of safety applications also bring new challenges to V2V communications. Spectrum sharing technology is considered as a promising solution. However, a single spectrum resource, such as reliable but limited bandwidth cellular spectrum resource (cellular band) or high bandwidth but easy blocked millimeter wave spectrum resource (mmWave band), can not satisfy the above stringent requirements. In this paper, we consider the integration of mmWave and cellular band communications and propose a Multi-Graph Coloring (MGC) algorithm to take full advantage of heterogeneous spectrum resource. We first formulate the problem of heterogeneous spectrum sharing in order to guarantee the latency and reliability requirements of V2V links and communication quality of Cellular Users (CUEs) while maximizing the data rate of V2V links. To ensure the solvability of this optimization problem, the packet latency constraint is transformed into a signal-to-interference-plus-noise ratios (SINR) constraint based on random network analysis. Then, due to the different communication characteristics of heterogeneous spectrum, we construct an interference multigraph and propose a MGC algorithm to find the solution of the optimization problem. Simulation results show that the proposed spectrum sharing scheme can improve the capacity of V2V links, ensure the latency and reliability requirements of vehicular users (VUEs) as well as guarantee the communication quality of CUEs.