This paper deals with network-coded multicast for real-time and streaming-media applications where packets have explicit expiration deadlines. Most of the popular network coding approaches require asymptotically large block-lengths, thereby incurring long decoding delays. The present paper introduces a joint scheduling and network coding design that aims to maximize the average throughput while respecting the packet deadlines. The novel approach relies on a time-unwrapped graph expansion in order to construct the network codes. The resultant algorithm draws from the well-known augmenting-path algorithm, and is both distributed as well as scalable. For networks with primary interference, a lower-bound on the worst-case performance of the algorithm is provided. The associated optimization problem is also analyzed from an integer programming perspective, and a set of valid inequalities is derived to obtain an upper bound.
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Manuscript received October 08, 2010; revised May 30, 2011; accepted August 01, 2011. Date of publication August 15, 2011; date of current version November 16, 2011. The associate editor coordinating the review of this manuscript and approving it for publication was Prof. Gerald Matz. This work was supported by the NSF by Grants CCF-0830480 and ECCS-0824007. The material in this paper was presented in part at the International Workshop on Wireless Network Coding, Rome, Italy, June 2009.
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