Lossy Joint Source-Channel Coding for Energy Harvesting Communication Systems
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Date
2014-12-15
Authors
Shahrbaf Motlagh, Meysam
Journal Title
Journal ISSN
Volume Title
Publisher
University of Waterloo
Abstract
In this work, we study the problem of lossy joint source-channel coding in an energy harvesting single-user communication system
with causal energy arrivals, where the energy storage unit may have leakage. In particular, we investigate the achievable distortion in the transmission of a single source with arbitrary
alphabets via an energy harvesting transmitter over a point-to-point channel.
We first establish a lower bound on the achievable distortion. Then, to minimize the distortion we consider an adaptive joint source-channel coding scheme, where the length of channel codewords
varies adaptively based on the available battery charge in each communication block. For this scheme, we obtain two coupled equations that determine the mismatch ratio between channel symbols and input symbols as well as the transmission power, both as functions
of battery charge.
As examples of continuous and discrete sources, we consider Gaussian and binary sources. In particular, for the Gaussian case, we obtain a closed form expression for the mismatch factor in terms of the $Lambert W$ function, and show that an increasing transmission power results in a decreasing mismatch factor and vice versa. We also numerically show that when the mismatch factor adaptively changes based on the available charge in the battery, the communication system achieves a smaller distortion compared to that of a constant mismatch factor.
Description
Keywords
Joint Source-Channel Coding, Energy Harvesting, Distortion, Resource Allocation