Variable SCH interval multichannel medium access control scheme with unsaturated channel in VANETs

IEEE 802.11p is a communication protocol which is extended by IEEE 802.11 standard, mainly used in Vehicular Ad-Hoc Networks (VANETs). VANETs generally include the Service Channel (SCH) and Control Channel (CCH). In the traditional 802.11p protocol, the length ratio between CCH and SCHs is fixed. This paper presents a variable SCH interval(VSI) multichannel medium access control (MAC) scheme under the non-saturated channel. Under this scheme, we can control the length of CCH interval and SCH interval. This paper uses three-dimensional Markov chain model to calculate the delay of WAVE service announcement (WSA) frame. We propose a VSI MAC calculation model under unsaturated condition to achieve the maximum throughput. The simulation results indicate that the proposed scheme can help VANETs increase the unsaturated throughput of SCHs and lower the transmission delay of data frames obviously.