Method and apparatus for efficient transmission of information to multiple nodes
A system and method to reduce the number of data transmissions between nodes in a network is described. In one embodiment, a system and method for reducing the amount of ACK and NAK traffic in a network is described.
1. In a wireless network having packet losses and comprising a plurality of nodes, the plurality of nodes comprising a source node and two or more other nodes including at least one intermediate relay node and at least one destination node, in which the plurality of nodes can overhear and store information that they receive with a sufficiently high signal to noise plus interference ratio and wherein random linear network coding is used by the at least one intermediate relay node to combine packets that the at least one intermediate relay node receives from other nodes, before repromulgating the received information, a method comprising:
transmitting a random linear combination of coded packets from the source node to the other nodes in the network;
at all nodes within reception range of the at least one intermediate relay node, determining with a desired degree of probability how many degrees of freedom the at least one intermediate relay node has received based upon one or more of information which has been overheard or directly transmitted from other nodes, node location information or a probabilistic channel model;
based upon the determined degrees of freedom, transmitting a new random linear combination of coded packets from one or more nodes within reception range of the at least one intermediate node to one or more of the other nodes in the network, wherein number of degrees of freedom received by the other nodes, or from blocks from other flows of which the at least intermediate relay node has knowledge are piggybacked on the new random linear combination of coded packets.
2. The method of claim 1 wherein new traffic originating at any node piggybacks information pertaining to the degrees of freedom received from other blocks from other flows.
3. The method of claim 2 wherein the nodes in the network have a priori knowledge of the probability that a packet transmitted from a specified node can be correctly received by another specified node.
4. The method of claim 3 wherein such a priori knowledge comes from location information that the nodes receive about each other as well as from the probabilistic channel model.
5. The method of claim 1 wherein transmitting a new linear combination of coded packets further comprises:
transmitting the new linear combination of coded packets further in response to number of degrees of freedom missing at the at least one destination node.