Dynamic Channel Coordination Schemes for IEEE 802.11p/1609 Vehicular Networks: A Survey

IEEE 802.11p/1609-based vehicular networks utilize a multichannel architecture to support vehicle-to-vehicle and vehicle-to-infrastructure communications. In the multi-channel architecture, the available channels in the 5 GHz spectrum are divided into one control channel (CCH) and multiple service channels (SCHs). Multiple SCHs are defined for nonsafety data transfer, while the CCH is used to broadcast safety messages called beacons and control messages (i.e., service advertisement messages). According to the channel coordination scheme, a radio interface alternately switches between the CCH and a specific SCH. The intervals during which a radio interface stays tuned to the CCH and SCH are called CCH and SCH intervals, respectively. Both intervals are set to a fixed value (i.e., 50 ms) in the standard. However, since the fixed-length intervals cannot be effective for dynamically changing traffic load, some dynamic interval division protocols have been recently proposed to support the dynamic adjustment of the CCH/SCH intervals for improving channel utilization. In this paper, we therefore provide a survey of dynamic interval division protocols for VANETs, discuss the advantages and disadvantages of them, and define some open issues and possible directions of future research.