John MacLaren Walsh

Learn More
— We discuss a coding technique for transmitting temporally ordered and/or successive refinements encoded multimedia data (such as MPEG video) over a multi-cast network using recently developed breakthrough network coding techniques. Hybridizing network coding philosophy with that of priority encoded transmission and fountain codes, we provide a method(More)
Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works, must be obtained from the IEEE. Contact: Abstract— Channel(More)
—The turbo decoder was not originally introduced as a solution to an optimization problem, which has impeded attempts to explain its excellent performance. Here it is shown, that the turbo decoder is an iterative method seeking a solution to an intuitively pleasing constrained optimization problem. In particular, the turbo decoder seeks the(More)
—A new computational technique is presented for determining rate regions for coded networks. The technique directly manipulates the extreme ray representation of inner and outer bounds for the region of entropic vectors. We use new inner bounds on region of entropic vectors based on conic hull of ranks of representable matroids. In particular, the(More)
—A computational technique for determining rate regions for networks and multilevel diversity coding systems based on inner and outer bounds for the region of entropic vectors is discussed. An inner bound based on binary representable matroids is discussed that has the added benefit of identifying optimal linear codes. The technique is demonstrated on a(More)
—The primary contribution is a finite terminating algorithm that determines membership of a candidate entropy vector in the set of binary entropy vectors Φ N. We outline the relationship between Φ N and its unbounded cardinality discrete random variable counterpart ¯ Γ * N (or its normalization ¯ Ω * N). We discuss connections between Φ N and ¯ Ω * N. For(More)
—Via multiterminal information theory, a framework is presented for deriving fundamental rate delay tradeoffs that delay mitigating codes must have when utilized over multipath routed and random linear network coded networks. The rate delay tradeoff is formulated as a calculus problem on a capacity region of a related abstracted broadcast channel. Given(More)
While its performance in the Gaussian, infinite block length, and loopless factor graph cases are well understood, the breakthrough applications of the belief propagation algorithm to the decoding of turbo and LDPC codes involve finite block lengths, finite alphabets, and factor graphs with loops. It has been shown in these instances that the stationary(More)