Resource Allocation for High-Reliability Low-Latency Vehicular Communications With Packet Retransmission

In vehicular communications, safety-critical information exchange has stringent reliability and latency requirements. However, lack of accurate instantaneous channel state information due to high mobility poses a great challenge to meet these requirements and the situation gets more complicated when packet retransmission is considered. Based on only large-scale fading channel information, we perform spectrum and power allocation to maximize the sum ergodic capacity of vehicular-to-infrastructure (V2I) links, while guaranteeing reliability and latency requirements of vehicular-to-vehicular (V2V) links. First, for each possible V2I-V2V spectrum reusing pair, we analyze the queueing system for the V2V link and derive the packet loss probability and average packet sojourn time under fixed power allocation. Then, an optimal power allocation is derived for each possible pair. Afterwards, we optimize the spectrum reusing pattern by addressing a polynomial time solvable bipartite matching problem. Simulation results confirm the accuracy of the proposed queueing analysis. Moreover, the proposed resource allocation strategy can improve the ergodic capacity of the V2I links under the precondition of guaranteeing the V2V links' requirements on reliability and latency.