Progressive Source-Channel Coding for Multimedia Transmission over Noisy and Lossy Channels with and without Feedback
Progressive Source-Channel Coding for Multimedia Transmission over Noisy and Lossy Channels with and without Feedback
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Date
2004-07-27
Authors
Chande, Vinay
Advisor
Farvardin, Nariman
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Abstract
Rate-scalable or layered lossy source-coding is useful for
progressive transmission of multimedia sources, where the receiver can
reconstruct the source incrementally.
This thesis considers ``joint source-channel'' schemes
for such a progressive transmission, in the presence of
noise or loss, with and without the use of a feedback link.
First we design image communication schemes for memoryless and finite
state channels using limited and explicitly constrained use of
the feedback channel in the form of a variable incremental redundancy
Hybrid ARQ protocol. Constraining feedback allows a direct
comparison with schemes without feedback. Optimized feedback based
systems are shown to have useful gains.
Second, we develop a controlled Markov chain approach for constrained feedback Hybrid ARQ protocol design.
The proposed methodology allows the protocol to be chosen from a collection of signal flow graphs, and
also allows explicit control over the tradeoffs in throughput, reliability and complexity.
Next we consider progressive image transmission in
the absence of feedback. We assign unequal error protection to the bits of
a rate-scalable source-coder using rate compatible
channel codes. We show that, under the framework, the source and
channel bits can be ``scheduled'' in a single bitstream in such a way
that operational optimality is retained for different transmission
budgets, creating a rate-scalable joint source-channel coder.
Next we undertake the design of a joint source-channel decoder that
uses ``distortion aware'' ACK/NACK feedback generation. For
memoryless channels, and Type-I HARQ, the design of optimal ACK/NACK
generation and decoding by packet combining is cast and solved as a
sequential decision problem. We obtain dynamic programming based
optimal solutions and also propose suboptimal, lower complexity
distortion-aware decoders and feedback generation rules which
outperform conventional BER based rules such as
CRC-check.
Finally we design operational rate-distortion optimal ACK/NACK
feedback generation rules for transmitting a tree structured quantizer
over a memoryless channel. We show that the optimal feedback
generation rules are embedded, that is, they allow incremental
switching to higher rates during the transmission. Also, we
obtain the structure of the feedback generation rules in terms
of a feedback threshold function that simplifies the implementation.