Network Vector Quantization

Abstract

A network source code is an optimal source code for a network. To design network source codes, we require each node to have a single encoder, which jointly encodes all messages transmitted by that node, and a single decoder, which jointly decodes all messages arriving at that node. Given a distribution over the sources, the design of the network source code jointly optimizes all encoders and decoders to obtain the best performance with respect to a user-defined priority schedule over the rates and distortions of the system. In this paper we focus on fixed-rate codes and address the implementation of an existing design algorithm for optimal network vector quantizers. Implementing the design algorithm is not straightforward since each encoder must choose its reproduction based on the expected behavior of sources that are unknown to it. We describe a new implementation approach and demonstrate its performance on a three-node network. In addition, we extend the design algorithm to allow the decoder at each node to use side information (specifically, the messages that are to be encoded by the encoder at the same node).

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