Efficient Groupcast Schemes for Vehicle Platooning in V2V Network

Abstract

Recently, groupcast has taken a lot of attention for vehicle platooning in vehicle-to-vehicle (V2V) network. In general, a traditional groupcast scheme by retransmission where source vehicle user equipment (S-VE) repeatedly transmits the same packet to destination VEs (D-VEs) is implemented in two ways; repetitive transmission for a predetermined number of times without receiving hybrid automatic repeat request (HARQ)-ACK/NACK from the D-VEs, and retransmission based on the HARQ-ACK/NACK. Although the former scheme is very easy to implement, it may lead to inefficient resource utilization due to excessive retransmissions. For the latter, the same problem arises when link quality between S-VE and D-VE is constantly poor. Hence, in this paper, we first investigate a heuristic scheme that can yield the superior performance of groupcast success rate with low computational complexity. Then, a groupcast scheme with the joint control of retransmission VE (R-VE) selection and time domain resource allocation is investigated by formulating a Markov decision process (MDP). The goal of the second proposed scheme is to find an optimal joint strategy for R-VE selection and time domain resource allocation that can minimize total time consumption while satisfying desired performance in terms of groupcast success rate. Simulation results validate that the proposed schemes significantly improve the groupcast success rate and the efficiency of time domain resource utilization, and greatly reduce the completion time of groupcast as compared with the two traditional groupcast schemes.