Layer-2 protocol design for vehicle safety communications in dedicated short range communications spectrum

This paper studies the design of layer-2 protocols for a vehicle or the roadside to send safety messages to other vehicles. The target is to meet vehicle safety applications´ requirements of high reliability and low delay in reception. The communication is one-to-many, local, and geo-significant. The vehicular communication network is ad-hoc and highly dynamic, with potentially large number of contending nodes. We design several random access protocols residing in MAC and MAC extension layers. The protocols fit the DSRC multichannel architecture. Analytical bounds of the protocols´ performance are derived. Simulations are conducted to compare the performance of the protocols in terms of reception reliability and channel usage efficiency. The sensitivity of the protocol performance is tested under various communication conditions as well as vehicle traffic conditions. The results show that our approach is a feasible solution to the MAC design problem to support vehicle safety communications.