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Type of Document Dissertation Author Liu, Junying URN etd-07202006-215833 Title Robust Transmission of Arithmetically Encoded Data Degree Doctor of Philosophy Department Electrical Engineering Advisory Committee
Advisor Name Title Daniel J. Costello Committee Member Ken Sauer Committee Member Robert Stevenson Committee Member Thomas Fuja Committee Member Keywords
- soft-input/soft-output
- arithmetic coding
- joint source/channel coding
Date of Defense 2006-04-12 Availability restricted Abstract Shannon's source and channel separation principle indicates that thereis no benefit ( in terms of efficiency or performance) to permitting cooperation between the source coding (compression) and channel coding (error control) functions in a digital communication system. However, this separation principle holds only
asymptotically for long and infinitely complex codes. This observation
has led to increasing research on joint source/channel coding
design as an alternative for achieving reliable communication over
noisy channels.
Joint source/channel coding schemes have been well studied for
fixed-length coded sources. But widely used entropy codes, such as
Huffman codes and arithmetic codes, are variable length in nature. The
compressed bit stream produced by variable length codes is susceptible
to error propagation. Thus joint source/channel coding design is of
interest for variable length codes. With the wide popularity of
arithmetic codes in a variety of standards including MPEG4,
JPEG2000 and H.26L, joint design for systems involving arithmetic
codes has generated interest. This dissertation focuses on the design of
schemes for recovering
arithmetically encoded data transmitted through a noisy AWGN channel.
The joint arithmetic/channel coding system presented in this dissertation is based on an
arithmetic sequential decoder that can accept soft input. Operating on
a source symbol-constrained tree structure, it improves
performance compared with the conventional
arithmetic decoder which can only accept binary bits. Several joint source/channel coding
schemes are proposed in which channel coding is used to protect the
arithmetically encoded data. First, a joint sequential decoder that
sweeps sequentially through a composite tree including the states of both
the arithmetic and channel codes is developed. Second, a soft tandem
system in which an arithmetic decoder uses the soft output from a
channel decoder is studied. The turbo principle is then applied to a serially
concatenated arithmetic/channel coding system in which the arithmetic
decoder and the channel decoder share extrinsic information as in
turbo codes. The convergence behavior of this iterative system
is analyzed via density evolution. All the joint systems
outperform the conventional hard tandem system in which arithmetic
decoding and channel decoding are done separately.
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