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An adaptive subband-based joint source-channel coder for image transmission Alavi, Amin
Abstract
An adaptive subband image coding system is proposed that uses DPCM and PCM codecs for source encoding the individual subbands, and a family of variable rate channel codes for forward error correction. A low resolution family of trellis coded modulation codes and a high resolution family of punctured convolutional channel codes are implemented and investigated. Implementation of unequal error protection among the subbands, and within the subbands, is examined for the two separate versions of our system. Simulations are performed on the AWGN channel and comparisons are made with corresponding systems that use only a single channel code, or that use the same family of codes for an adaptive equal error protection scheme. Our proposed adaptive systems outperform any of the systems that use only a single channel code greatly, extending the useful SNR range by an amount that depends on the code family. As well, our systems outperform the corresponding adaptive equal error protection systems by as much as 2 dB PSNR. This is primarily due to the use of unequal error protection among the subbands, as surprisingly little additional gain is achieved by applying unequal error protection within the subbands. We use and improve a known modelling technique which enables the system to configure itself optimally for the transmission of an arbitrary image, by only measuring the mean of lowest frequency subband and variance of each of its subbands. Because our systems require an estimate of the channel SNR, we have investigated the sensitivity to poor channel SNR estimation, and have found negligible performance loss for channel mismatches up to 1.5 dB.
Item Metadata
Title |
An adaptive subband-based joint source-channel coder for image transmission
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1999
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Description |
An adaptive subband image coding system is proposed that uses DPCM and PCM codecs
for source encoding the individual subbands, and a family of variable rate channel codes
for forward error correction. A low resolution family of trellis coded modulation codes
and a high resolution family of punctured convolutional channel codes are implemented
and investigated. Implementation of unequal error protection among the subbands, and
within the subbands, is examined for the two separate versions of our system. Simulations
are performed on the AWGN channel and comparisons are made with corresponding
systems that use only a single channel code, or that use the same family of codes for
an adaptive equal error protection scheme. Our proposed adaptive systems outperform
any of the systems that use only a single channel code greatly, extending the useful SNR
range by an amount that depends on the code family. As well, our systems outperform
the corresponding adaptive equal error protection systems by as much as 2 dB PSNR.
This is primarily due to the use of unequal error protection among the subbands, as
surprisingly little additional gain is achieved by applying unequal error protection within
the subbands. We use and improve a known modelling technique which enables the
system to configure itself optimally for the transmission of an arbitrary image, by only
measuring the mean of lowest frequency subband and variance of each of its subbands.
Because our systems require an estimate of the channel SNR, we have investigated the
sensitivity to poor channel SNR estimation, and have found negligible performance loss
for channel mismatches up to 1.5 dB.
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Extent |
6248039 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-06-16
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0065346
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1999-11
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.