Patent ID: 8250426
Filing Date: 2012-08-21
Classification: H04L

Abstract:
1. A method of scheduling and encoding data packets for transmission in a multicast session from a sender to a multicast group of receivers including at least two receivers in a multicast ARQ (Automatic Repeat reQuest) communication system for transfer of a given amount of multicast information, wherein the following steps are performed at each of a plurality of scheduling instances: obtaining feedback information from said at least two receivers indicating received data packets; forming at least one composite data packet as a weighted linear combination of regular data packets based on a corresponding weight vector comprising a set of coding weights; adapting, for each of said at least one composite data packet, said coding weights of said weight vector based on said feedback information such that the composite packet represents a linear combination of regular data packets that is linearly independent, for each receiver of those receivers of said multicast group that still need to receive one or more multicast data packets, of any data packet previously received by the receiver during said multicast session; said sender transmitting said at least one composite data packet to those receivers of said multicast group that still need to receive one or more multicast data packets, wherein said coding weights, at each of said plurality of scheduling instances, are adaptively selected such that, for each receiver of at least a set of said receivers, the weight vector will increase the rank of a receiver-specific matrix of weight vectors for previously received data packets if the weight vector is added to said matrix.