Node scheduling scheme of sensor nodes is one of the most important method to solve the energy-constrained wireless sensor networks.Traditional methods of node scheduling that without location information are aim at node sensing area coverage.It leads to a node in the border of monitored region first death due to no more chance enter into sleep state

and then the death spread to the central region.We call this phenomenon as inequality sleep problems.To address this problem

from the theoretical analysis of the sensor node coverage model

we proposed the concept of tolerable coverage area

and propose a node scheduling scheme based on tolerable coverage area.Simulation results demonstrate that the proposed method not only alleviates the inequality sleep problems

but also prolonged network lifetime.