Improving Delay Performance for Time-Critical Communications in VANET

To ensure the functionality of intelligent transportation, time-critical information is of great importance in Vehicular Ad-hoc Network (VANET). Meanwhile, non-time-critical information still exists in the network, with which regular services can be provided. A key problem in VANET is to guarantee delay performance for time-critical traffic while still satisfying demand of non-time-critical traffic. To achieve this object, a multiple threshold policy derived from TEOS (Threshold Enabled Opportunistic Scheduling) is studied in this paper. With this policy, overall channel efficiency is optimized while a throughput requirement from the non-time-critical traffic is still considered. Thus, two objects can be achieved simultaneously: time-critical packets can have a better channel access probability as a result of a more free channel; and non-time-critical traffic can be transmitted as required. Numerical results and simulations show that this approach can provide smaller delay for time-critical transmissions in VANET.