Research On Delay Reduction Algorithm Of Ad Hoc Network Based On Improved Routing Protocol

The traditional anti-collision in the operation section of large railway maintenance machinery(hereinafter referred to as "large machinery")mainly depends on the wireless communication between large machinery operators.However,since the working hours of large machinery are generally in the early morning,the staff are prone to fatigue and the environment is poor,the large machinery operators may fail to brake in time due to sudden conditions,which may collide with subsequent vehicles,resulting in personnel and property losses.In order to avoid such potential safety hazards,each large machine can communicate by installing an anti-collision device to form a centerless ad hoc network(Ad hoc),so as to exchange the location information of itself and neighboring large machines in real time.In order to determine the distance between large computers in time,the real-time performance of wireless communication is the key.How to reduce the delay of information transmission between large computers is a difficult problem,which is also the problem that this paper tries to solve.The traditional ad hoc network routing protocol does not consider the communication conflict caused by hidden nodes and exposed nodes.When nodes communicate,data packet conflict will occur,resulting in data loss,and data retransmission will increase the transmission delay.By analyzing the wireless network node communication model,taking the time service information in the Beidou signal on the anti-collision equipment as the time benchmark,combined with TDMA(time division multiple access)slot allocation algorithm and multipath routing traffic allocation algorithm,improving the routing protocol,and carries out relevant simulation verification on the improved protocol.The main work of this paper is as follows:(1)Based on the node communication model of ad hoc network,the causes of hidden nodes and exposed nodes and the increase of delay are studied.The delay reduction scheme based on time slot allocation and multi-path routing traffic allocation is given.The time slot allocation model and multi-path routing traffic allocation model based on TDMA are built by using NS3 network simulation software.(2)Aiming at the problem that the traditional dynamic slot allocation algorithm eca-tdma(effective conflict avoiding TDMA)does not consider the increase of scheduling delay caused by whether the traffic flow direction is consistent with the time slot,a conflict free scheduling algorithm based on the traffic flow direction is proposed.The algorithm divides the time frame into reservation subframe,confirmation subframe and information subframe,establishes one hop time slot table and two hop time slot table in the reservation stage and confirmation stage,and obtains the time slot occupation of information subframe of neighbor nodes according to the one hop time slot table and two hop time slot table,so as to allocate time slots without conflict.At the same time,the algorithm provides a slot exchange mechanism.Nodes can exchange slots with their neighbors,and finally achieve that the slot allocation order is consistent with the service flow order.AODV protocol is improved by conflict free scheduling algorithm,and the improved protocol is simulated by NS3 simulation software.The simulation results show that the improved protocol has a certain degree of improvement in network throughput,packet delivery rate and end-to-end delay.(3)Based on the M/M/1 queuing service model,a multi-path and multi hop routing delay model is built.An optimal solution of traffic allocation is obtained by constructing Lagrange equation,and a new traffic allocation algorithm is given.The core idea is to balance the traffic in the network by measuring the transmission delay on each sub path and calculating the traffic allocation weight of each sub path by using the optimal solution of traffic allocation.The AOMDV protocol is improved through the traffic allocation algorithm,and the improved protocol is simulated by NS3 simulation software.The simulation results show that the improved protocol will give priority to the traffic to the path with unsaturated traffic,prevent network congestion and reduce the average end-to-end delay.