Memorised carrier sense multiple access with collision avoidance (MCSMA/CA) protocol for IEEE 802.11p

The wireless access in vehicular environment (WAVE) architecture has been standardised in the IEEE 802.11p specification in order to be widely deployed in roadway environments. The aim of the WAVE networks is to provide prompt emergency information as well as internet connectivity. However, the IEEE 802.11p contention-based medium access control (MAC) protocol would deteriorate transmission efficiency if the number of on-board units (OBUs) contending on an SCH is large. Moreover, synchronizing all WAVE devices that perform channel switching may experience a period of above-average channel congestion immediately following a channel switch, possibly resulting in an unexpectedly high collision rate. As a solution, we propose an efficiency improvement scheme, namely memorized carrier sense multiple access with collision avoidance (MCSMA/CA) protocol, which improves the SCH throughput by means of a channel context switch mechanism. Numerical and simulation results demonstrate that the proposed scheme significantly promotes the standard transmission efficiency.