Infoscience

Thesis

Cooperative coding on orthogonal information networks

The focus of this thesis is on communication over cooperative information networks. In the first half of the thesis, we consider lossy source coding problems where a relay assists in the communication of a source stream between two terminals. The following two configurations are studied – (1) The Slepian-Wolf problem setup when the two encoding terminals are allowed a certain degree of collaboration in describing the source to the decoder and (2) A cascade communication system where the communication between the source and the destination is enabled through a relay (or a set of relays). We characterize rate-distortion tradeoffs and compute it explicitly for specific cases when the sources are respectively, jointly Gaussian and binary symmetric. In the second half of the thesis, we consider channel coding over orthogonal information networks. In particular, we find bounds to the capacity region of networks of Multiple Access Channels (MACs) and networks of Deterministic Broadcast Channels (DBCs). We propose a two layered achievability scheme for communication over such networks – consisting of a physical layer that involves "cleaning up" the constituent channels in the network to create a point-to-point wired overlay, and a network layer that involves routing over this wired overlay. We also consider two multicast problems over orthogonal networks. The first problem is the multiple-access multicast problem over a network of DBCs. In the second problem, we consider multicasting a common message along with independent "private messages" from a source node to a set of receivers on a wired network and characterize the capacity region when the network satisfies a certain min-cut property.

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