Patent ID: 8005002

Claim:
A method for performing a query-based convergecast scheduling in a convergecast network which comprises a base-station and a plurality of nodes, wherein during a convergecast operation the plurality of nodes transmit packets to the base-station, the method comprising: receiving information which represents a logical convergecast tree for the convergecast network, wherein the logical convergecast tree comprises one or more branches; wherein each node in the logical convergecast tree is associated with a hop count for a route to the base-station through a specific branch; and wherein each node can generate zero or more packets to transmit; initializing a query from the base-station, wherein the query is successively propagated to the plurality of nodes through the branches; in response to the query, computing distributed timing information which indicates at least packet transmission information associated with a first node based on a query received from a second node, wherein the query includes timing information associated with the second node; updating the query to include timing information associated with the first node by computing intermediate timing information based on timing data which indicates the first time the first node transmits a packet to the base station and the number of packets generated by the first node; aggregating the distributed timing information associated with the plurality of nodes toward the base-station through the branches; forwarding the aggregated distributed timing information to the plurality of nodes; and constructing, at each node, an optimized convergecast schedule for the logical convergecast tree based on the aggregated distributed timing information.