A WSN Energy Efficient Routing Algorithm For Railway Slope Monitoring

With the rapid development of modern high-speed railway in our country,the state has put forward higher requirements for the safe operation of trains.The railway slope monitoring system can monitor the railway environment in real time and efficiently to ensure the safe running of trains.Because of the high construction cost and inconvenient maintenance,the traditional monitoring system of slope can not meet the needs of large area railway slope monitoring.Wireless sensor network（WSN）is more suitable for railway slope monitoring system because of its advantages of low node cost,flexible networking and large coverage area.Because the energy carried by sensor nodes is limited,it is not convenient to replenish when the battery is exhausted,so how to use the limited energy to prolong the life of WSN network is the research focus.One of the energy saving technologies of WSN is the design of energy-efficient routing algorithm.The key nodes around the sink nodes receive and forward the data from the common nodes,so that the key nodes die prematurely.In a fixed network size,the number of sink nodes can be increased to balance the data forwarding tasks of key nodes and avoid the"energy hole".However,the cost of sink nodes is much higher than that of sensor nodes,and the effect of excessive deployment of sink nodes on WSN network lifetime is not obvious.At the same time,the selection of forwarding nodes from common nodes to sink nodes is also very important.Multi-hop transmission can balance the energy consumption of nodes and improve the network life.In this thesis,we propose an energy-efficient routing algorithm based on fast clustering based on node local density（FCNLD）for the optimal deployment of multi-sink nodes and the selection of forwarding nodes and multi-hop transmission.The main contents of this thesis are as follows:（1）Optimal deployment of multiple sink nodes:According to the geographical characteristics of long and narrow railway lines,increasing the number of sink nodes can reduce the number of forwarding hops from ordinary nodes to sink nodes and thus prolong the network life.However,the cost budget is also an important factor to be considered in practical engineering applications.When the number of sink nodes increases to a certain extent,the effect of network lifetime prolongation becomes less obvious,and the network cost increases sharply.Based on WSN stochastic topology,this thesis establishes network lifetime and network cost model,constructs the ratio function H of network lifetime and network cost,and proves that the function is strictly convex and derives the expression N_sinkof the optimal number of nodes.Given the number of sink nodes,the location of the sink node becomes particularly important.When sink nodes are distributed in denser nodes,there are more key nodes in the network,which can balance the data from common nodes to the greatest extent.In this thesis,the local density factor and distance factor of sensor nodes are defined.Both of them construct a clustering decision function N_sink node is the best node location before intercepting.Proper deployment of multiple sink nodes extends the lifetime of the WSN while controlling network costs.（2）Next hop election and data transmission mechanism:According to the classical energy consumption model,the communication distance has a great impact on the energy consumption of sensor nodes,and the energy consumption of nodes increases sharply after exceeding the distance threshold.Therefore,the concept of limited distance band is introduced in route selection:key nodes within the communication range of sink nodes communicate directly with sink nodes;other ordinary nodes look for alternative forwarding nodes on the upper level.Define the next-hop node selection parameters:Synthesize the search angle and residual energy in the alternative nodes,and select the node with low selection parameters as the forwarding node to prolong the network lifetime.（3）Compared with LEACH algorithm,RDF algorithm and IPSCO algorithm,the proposed algorithm is compared in four aspects:clustering effect and multi-hop path,life cycle,number of received packets and network energy consumption change with time.The results show that the proposed FCNLD energy efficient routing algorithm can effectively balance and reduce energy consumption of nodes,and prolong network life.