Smoothing the Drive: Critical Access for Intelligent Transportation Systems

Long-term evolution (LTE)-based vehicular-to-everything (V2X) service is one of the promising technologies for supporting intelligent transportation systems (ITSs). LTE adopts a request-grant approach for allocating wireless resources. Each user follows a contention-based random access (RA) procedure to transmit its request. However, this procedure may result in unbounded delay if too many users compete for limited RA resources. Therefore, prioritized critical access in the LTE RA procedure is required to differentiate critical V2X services from noncritical ones. This article presents a generalized preamble allocation strategy that can be used to offer prioritized channel access for V2X service through flexible preamble allocation. Simulation results show that the proposed scheme can prioritize the critical ITS service and fulfill its stringent timing and reliability requirements.