Patent ID: 8423657

Claim:
A time slot allocation method for reducing consumption of energy in a wireless sensor network, the method comprising the steps of: receiving, by an upper node, reports from a plurality of lower nodes, respectively, each report indicating whether there is data to be transmitted to the upper node from a respective lower node; generating, by the upper node, a time slot allocation policy for data transmission between the upper node and the plurality of lower nodes, based on the received reports; transmitting, by the upper node, the time slot allocation policy to the plurality of lower nodes; and transmitting and receiving, by the upper node, data to and from at least one of the plurality of lower nodes based on the time slot allocation policy, wherein the time slot allocation policy indicates, for each of the plurality of lower nodes, one of (1) an interval for entering an active mode for data transmission, when there is data to be transmitted between the upper node and a respective lower node, and (2) to remain in a sleep mode, when there is no data to be transmitted between the upper node and a respective lower node.