Patent ID: 7356561

Claim:
In a multiple node network, a method comprising: receiving, at least one node, residual energies from neighboring nodes; waking up the least one node from a sleep mode after sleeping a period of time determined based on a residual energy of the at least one node and the received residual energies for the neighboring nodes and during one or more wake-up slots of a network time-slotted frame, the sleep mode being a low power consumption mode; receiving data, at the awakened node, from one or more neighboring nodes that may have transmitted data during one or more of the wake-up slots of the awakened node; determining, at the awakened node, if one or more neighboring nodes belonging to one or more sleeper classes will awaken using a wake-up determination process employed by the one or more neighboring nodes and the received data, the sleeper classes including at least a short sleeper class and a long sleeper class; and transmitting, from the awakened node, in one or more wake-up slots of the neighboring nodes, if there is data to be sent to one or more of the neighboring nodes, based on the determination of when the neighboring nodes wake up from their respective sleep modes.