Since sensor nodes are generally constrained in on-board energy supply, saving energy is crucial in extending the lifetime of the wireless sensor networks. In this paper, we present a dynamic threshold scheme used in the data propagation phase of Directed Diffusion, which can decrease the traffic between nodes and therefore prolongs the longevity of wireless sensor networks. The sensor node sends data to the sink only when the sampling value reaches the hard threshold and the difference between the current sample value and the last sent value is greater than the soft threshold, which reduces data traffic to conserve energy. The soft threshold will be adjusted by using the historical values to make the proportion of sending due to timeout equal to the expected value. Whether the values of a sensed attribute change drastically or not, the data sent will continue at a reasonable rate, which adapts the sensor network to the changeful circumstance. Simulation results show that the improved Directed Diffusion based on dynamic threshold can prolong the network lifetime about 35% compared with the original system and can reacting immediately to drastic change in the values of a sensed attribute.
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- Dynamic Threshold Scheme Used in Directed Diffusion
- Springer Berlin Heidelberg
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