Research On Routing Algorithm For Linear Topology WSN Under Delay Constraint

With the rapid development of high-speed railway in China,higher requirements have been put forward for the safety of train operating environment.Wireless sensor network has the advantages of flexible structure,simple wiring,low node cost,wide coverage and strong adaptability to the environment.Wireless sensor network can not only meet the requirements of railway environment for the accuracy and breadth of monitoring data,but also monitor railway infrastructure and various natural environmental disasters.Wireless sensor network can save the construction cost of environmental monitoring network along the railway and facilitate the later maintenance.Therefore,wireless sensor networks are particularly suitable for large-scale deployment along the railway,and can complete real-time monitoring tasks in harsh and remote environments for a long time.The energy of sensor nodes is limited,and the nodes closer to the sink in linear topology wireless sensor networks consume more energy,which leads to the problem of "energy hole",and the linear wireless sensor networks in the environmental monitoring scenario along the railway also need to quantitatively analyze the data transmission delay.Therefore,how to effectively balance the energy consumption of nodes and reducing transmission delay of the monitoring network are the key points of the research on linear wireless sensor networks along the railway.According to the characteristics and application requirements of linear wireless sensor networks along the railway,this dissertation proposes two improved algorithms.The main work of this dissertation are as follows:(1)In linear wireless sensor network for railway environment monitoring,aiming at the problem that single-hop transmission aggravates the energy exhaustion of nodes and shortens the network lifetime,combining with the requirements on low energy consumption and high real-time of railway environment monitoring,an energy-balanced data transmission strategy for linear wireless sensor network is proposed.Based on the Lagrange multiplier method,it is verified that the energy consumption of non-uniform cluster head deployment is lower than that of uniform deployment,the cluster head complete the optimal deployment in a geometric progression,two-sided and the non-uniform manner.Based on this model,the mathematical relationship between the hop counts,cluster head energy consumption and the network lifetime of K-hop packet transmission strategy is established.Simulation results show that compared with single-hop transmission strategy,the proposed K-hop packet transmission strategy reduces the hop counts and the energy consumption difference of cluster head and consequently prolong the network lifetime by about 1.6 times,which meets the high requirements of real-time,energy consumption and robustness of the railway environment monitoring network.(2)Aiming to solve the environmental monitoring problem along the railway in linear wireless sensor network scenario,an energy-saving routing algorithm based on particle swarm optimization theory and breadth first search is proposed.The research idea of the algorithm is as follows: Adopt the non-uniform deployment mode of nodes along the two sides parallel to the track line.By selecting the particle with higher residual energy as the initial particle and combining the linear decreasing inertia weight strategy,the defect that the particle swarm optimization algorithm is easy to fall into the local optimum is effectively avoided.The fitness function is constructed with the goal of balancing the energy consumption of nodes and the optimized clustering is completed.At the same time,considering the node transmission energy consumption and delay,the path cost function is constructed,and the path cost function is dynamically adjusted based on the residual energy of nodes.The low-energy node protection mechanism and alternative path updating mechanism based on Q-learning are adopted to alleviate the transmission interruption caused by the narrow and long railway environmental monitoring area.The simulation results show that the proposed algorithm can effectively balance the energy consumption of the monitoring network,and improve the reliability of the network while prolonging the network lifetime and reducing the network delay.