Research Based On Energy Efficient On-demand Cache Strategy In Wireless Sensor Network

In recent years, wireless sensor network (WSN) has received the attentionfrom all walks of life, a lot of research has been gradually achieved,but there are stillsome problems,such as data access latency,network congestion and energyconsumption, etc.Researches show that,caching technology in WSN can solve theabove problems.But, in overseas,caching technology for wireless sensor networkresearch is in the preliminary stage of development, the domestic research is moreless. So, it has important significance to carry out the research of cachingtechnology in wireless sensor network.Caching technology and wireless sensor network (WSN) is introduced in thispaper.Researched caching strategies is cache placement algorithm and cachereplacement algorithm, and cache placement includes selecting cache node andstoraging cache data items. The main work is as follows:1. A strategy includes an algorithm of selecting cache node that cache node candisperse in the network and a strategy based on energy of storaging data items todetermine whether the cache node should storage data items are proposed.Details are as follows:(1) If the distance between the source node and sink node is less than3hops,the sink node can obtain data items directly from the sourcenode,otherwise,then dichotomy is used to select cache node in the pathbetween source node and sink node,it lets cache node dispersed in thenetwork. It can balance cache node energy consumption.(2) After selecting cache node,If the cache node residual energy is more thanthe setting threshold energy, then the cache node should store data item, itcan avoid the cache node die prematurely because of excessive energyconsumption.2. A new methods of obtaining weight function of cache replacement algorithm isproposed.Then a new algorithm of cache replacement is obtained. Details are asfollows: (1) Analysis the energy of cache found of the sink node before and after cachereplacement,then getting some factors reducing sink node caching foundenergy consumption.(2) These are access probability of cache objects Pt and size of cache objectsSt. In order to ensure that the cache data item is not out of date, cachedobjects produce time Time is considered.These form weight functiongain of the cache replacement algorithm. When caching replacement, thecache object of lower access probability, more larger took up space andmore longer produced time is choiced to be replaced. NS2simulationresults show that, compared other cache algorithm, the algorithm improveson average hop,is35.6%lower on average energy consumption, reduces31.6%on average delay,increases8.16%on cache hit ratio.