Study On Adaptive Link Quality Estimation Mechanism For Wireless Sensor Networks

With the development of WSN (Wireless Sensor Networks) technologies,nowadays, it has been applied in many fields, such as military, medical facilities,environment observation and others. However, it still has following limitations：1) theunpredictable and hostile environment in which sensor nodes be deployed;2)Sensornodes is vulnerable to inner/outer noises and other disruptions, and this will cause theerror and packet loss;3) beside that, as nodes are powed by battery, so nodes can notwork once the power use up. Therefore, there is necessary to introduce link qualityestimation methods into WSN to ensure the high successful rate of packettransmission transmitted messages on the desired links, meanwhile reduce the energyconsumption which caused by data retransmission and eventually extend the life spanof in the whole network.At the beginning, this paper do analysis of the reasons which causes theunreliable of link in WSN, and then gives a detail description of WSN linking and theeffects on the performances of upper layers, beside that this paper also give a deepanalysis to current estimation method of the link quality in WSN. Based on the aboveanalysis, this paper introduce an adaptive link quality estimation method (ALQE)which build based on EWMA(Exponentially Weighted Moving Average), it dividesgeneral link into stable and unstable, give a estimation of the stability of depending onRSSI which learned through passive manner, and use give different weight to differentlink to do evaluation of current link quality.Experiment results show that the validity and stability of the algorithms whichproposed in this paper, meanwhile it can react quickly to the suddenly change of thelink, which can be used by route protocol do route selection, compared with originalEWMA mechanism, the method proposed in this paper improved the estimationperformance without extra overhead, and it is suitable for energy limited sensor nodes.