Scheduling algorithm based on preemptive priority and hybrid data structure for cognitive radio technology with vehicular ad hoc network

There are different types of messages containing different priorities in vehicular ad hoc networks. Hence, queue rescheduling is required according to priorities of arrived messages. In this study, a data structure with less computational complexity is proposed to minimise queuing delay. Further, to maintain quality of service, preemptive priority is applied to time-bound safety messages by transferring non-safety messages to other bands using the concept of cognitive radio technology. The time-bound messages are transmitted using the dedicated short-range communication spectrum without the need for spectrum sensing by vehicles. The other messages with no deadline constraint are switched to other bands near-dedicated short-range communication spectrum. The results show that 6.25% improvement in packet delivery ratio of cognitive radio-enabled preemptive priority is achieved in comparison to existing cognitive radio protocol. The delay shows a slight increment of 1.1%. The packet delivery ratio of cognitive radio-enabled non-preemptive priority is improved by 3.24% while the delay is improved by 3.17%. The data storage required for storing sensing data of 50 channels for 10 days is only 45 Mb.