CO-HCCA: Bandwidth Allocation Strategy in Internet of Vehicles with Dynamically Segmented Congestion Control

Hybrid coordination function controlled channel access (HCCA) applied in wireless ad hoc net­work systems is the strategy to allocate the bandwidth resources of control channel (CCH) and service channels (SCHs). With the continuous development of Internet of vehicles (IoV) technologies, it is difficult for HCCA to support traffic information services, such as low delay along with high-frequency dissemination of security beacons and large capacity interaction of image data. Fusing the fundamental theories of No.7 signaling system and 5G-IoV technologies, this paper proposes a novel channel bandwidth allocation strategy named CO-HCCA, which matches CCH time slot numbers with on board units (OBUs) numbers to reduce the congestion of channel access demand information (CADI); and also illustrates a dynamic segment adjusting algorithm of the time slots. On one hand, in the channel reservation stage of CCH control cycle, OBUs are sorted according to the priority of data transmission, and then the corresponding transmission slots are adopted orderly according to the OBUs numbers, so as to decrease the collision probability of high-frequency dissemination of CADI. On the other hand, for the quickly arriving and leaving OBUs in coverage of roadside base station (RBS), the prediction of bandwidth segments is dynamically adjusted to adapt to the time-varying characteristic of the connected vehicle scenarios. Modeling calculation and objective comparison on OMNeT++ computing platform show that the proposed CO-HCCA strategy can effectively reduce the channel congestion of IoV, and in the scenario of high-density data interaction, it is beneficial to promote the transmission timeliness of security beacons and the package delivery rate (PDR) of high bit-rate multiple information.