Coding packets over reordering channels

We define the “reordering channel” which approximates packet communication over multipath networks. We consider deterministic packet arrivals with finite horizon decoding of individual packets and analyze the error probability for a two stage coding scheme

Coding packets over reordering channels

We define the “reordering channel” which approximates packet communication over multipath networks. We consider deterministic packet arrivals with finite horizon decoding of individual packets and analyze the error probability for a two stage coding scheme

Plan-and-Fill Scheme for Semantic Parsing

Semantic parsing processes natural language queries to convert them into a structured parse. This disclosure describes a two-stage scheme for semantic parsing, comprising a plan stage and a fill stage. In the plan stage, the intent or plan behind an input query is identified. In the fill stage, a parse is generated by filling the plan with the relevant span from the query. The separation of parsing into plan and fill enables decoupling losses corresponding to basic intent generation (plan) and span identification (fill) stages. The described techniques provide the flexibility to decouple model parameters that correspond to the two stages. The described techniques provide an efficient alternative to sequence-to-sequence models that use both an encoder and a decoder for parsing

Scheduling jobs with hard deadlines over Multiple Access and Degraded Broadcast Channels

We consider the problem of scheduling jobs with given start and finish times over two classes of multi-user channels, namely Multiple Access Channels and Degraded Broadcast Channels, and derive necessary and sufficient conditions for feasible scheduling of the jobs

Achievable Flows on Orthogonal Information Networks

We examine routing over two classes of orthogonal information networks. The first is a relay network with orthogonal inputs. The nodes in this network do not broadcast, but communicate to the different nodes via independent inputs. There is multiple access interference at every node. The second network is the Gaussian broadcast network with no interference. The nodes in this network broadcast, but the signals from the different transmitter nodes do not interfere at any receiver node. Such models can be motivated by communication schemes which use non overlapping time/frequency slots and which selectively ignore the effect of interference. Inner bounds to the capacity region for both classes of networks are obtained using modified max-flow theorems

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

On the Heegard-Berger/Kaspi problem with decoder cooperation

We consider decoder cooperation in the Heegard-Berger/Kaspi problem. The encoder sends a common description of a source to two decoders, one of which has side information. Cooperation between the two decoders is of the form of a limited capacity link from the informed decoder to the uninformed decoder. Inner and outer bounds are obtained to the rate distortion region for this problem. The bounds are shown to coincide for the case where the better informed decoder wants to recover X losslessly and also for certain distortion regimes in the quadratic Gaussian case. The rate distortion tradeoff is completely characterized for the case when the encoder also has access to the side information. Finally, we look at the case when the two decoders want to losslessly reconstruct functions of X and characterize the achievable rate region