HARQ feedback optimization techniques for improved reliability in Cellular Vehicle to Everything.

Vehicle to Everything (V2X) communication has been a topic of great interest for the past decade. Lately, a push from the automotive industry and regulators for inclusion of advanced use cases towards autonomous vehicles, has led to the search for improved solutions that can support the respective features. In this paper, Hybrid Automatic Repeat Request (HARQ) feedback solutions are explored in the context of group communications (groupcast) in cellular V2X. A solution is provided to combine reliability improvements while using the least possible amount of sidelink resources. Furthermore, for the case where members of the group are out of communication range of the transmitter, it is suggested to use the feedback response for selecting another member of the group to forward the message.