Priority-Based Hybrid MAC Protocol for VANET with UAV-Enabled Roadside Units

Table 1

Symbols summary for model analysis.

Parameters	Description
N	The number of time slots in priority-based adaptive TDMA period.
	The collision probability of transmission.
	The success probability of packet transmission.
	The probability that there is a packet to be sent.
	The probability that the channel is busy.
	The probability that a node transmits a data packet in an arbitrary time slot.
	The number of nodes contending for transmission simultaneously.
	The maximum contending slot length of x priority message in the ith slot (x = highest/second/normal).
	The time cost on highest priority message transmission of OBU.
	The time cost on second priority message transmission of OBU.
	The time cost on normal message transmission of OBU.
	The time cost on control message transmission.
	The time cost on contending of x priority information.
	The time cost on packet transmission of an x priority message.
	The time cost on retransmission of an x priority message.
	The total throughput of the networks.
	The throughput of RSU-RSU transmission.
	The throughput of OBU-RSU transmission.