C-V2X Mode 4 Resource Allocation in High Mobility Vehicle Communication

This paper reports the results of investigations of autonomous resource selection for the Cellular-Vehicle-to-Everything (C-V2X) Mode 4 of LTE. We have investigated the system-level performance of sensing based Semi-Persistent Scheduling (S-SPS) algorithm that has been proposed by 3GPP for resource allocation scheduling and our newly proposed Extended-Estimation and Reservation Resource Allocation (E-ERRA) algorithm. It is known that S-SPS faces collision problems in resource allocation. The ERRA algorithm previously introduced by the authors has solved this collision problem by pre-allocating the first received packet that has the same value of the Random Counter (RC). RC gets a value generated randomly when the reselection is needed and is decreased by one in each broadcast cycle. Furthermore, the extension of ERRA (E-ERRA) introduced in this paper is aimed at solving the problem of the lost reserved resources when the vehicle with preallocated resources has just left or appeared in the broadcast range before the re-selection process. E-ERRA specifies an alternative list of resources to use when this problem appears. It has been proven that E-ERRA is a promising way to support efficient and reliable vehicular communications by choosing and announcing the next resource allocation. The decrease in the collision ratio (CR) and increase of the packet reception ratio (PRR) that are shown in the paper indicate that E-ERRA performs substantially better than S-SPS in reliable broadcasting and resource allocation for vehicle transceivers operating in C-V2X Mode 4.