Reliable Transmission Method For Emergency Messages In Flying Car Networks

In the ground transportation networks,traffic congestion and traffic accidents often occur.The development of flying car technology provides effective solutions to the current problems in land transportation.In the flying car networks,the distribution of emergency messages is of great significance and needs to meet the requirements of reliability and realtime.The current emergency message distribution in flying car networks faces challenges such as high mobility of flying cars and instability of wireless channels.In order to achieve the reliability of the transmission of emergency messages in the flying car environment,the average one-hop transmission delay in multi-hop transmission more lower,the average one-hop transmission distance in multi-hop transmission more farther,and the successful acceptance rate of emergency messages more higher.This thesis constructs a hierarchical model suitable for flying car,proposes an in-layer motion model and an inter-layer motion model,and a channel fading model that fits the air environment.on this basis,proposes the Multi-hop transmission of emergency messages in the flying car environment.In this method,when the source node sends an emergency message,other flying cars within its communication range will pass the angle threshold condition to become a competing node.The competing node calculates the competing waiting time by combining the source node,its own location information and the signal-to-noise ratio.When the competition waiting time of the competing node ends,the competing node broadcasts an emergency message and becomes a relay node,and other neighbor nodes within the communication range of the competing node will abandon the competition after receiving this broadcast.When the response mechanism is completed,it means that the one-hop transmission of the emergency message is completed.In the one-hop transmission of the broadcast message,in order to transmit emergency messages to a specific effective area,this thesis proposes an emergency message transmission method based on the angle threshold.At the same time,in order to ensure the reliability of emergency message transmission and reduce the transmission delay of emergency messages,this thesis proposes a method of implicit response and response separation based on the timeout retransmission mechanism of the source node.Finally,aiming at the conflict problem of simultaneous broadcasting of multiple nodes in the process,this thesis designs a conflict resolution mechanism solution.This thesis simulates the flying car networks scenario using SUMO and NS3 simulation tools,and verifies the effectiveness of the emergency message distribution method proposed in this thesis.Compared with the two emergency message transmission methods in terms of average one-hop transmission delay,average one-hop transmission distance and successful reception rate,experiments show the effectiveness of the method proposed in this thesis...