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Description:
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Driven by a host of emerging applications (e .g . , sensor networks and wireless
video ) , distributed source coding (i .e . , Slepian -Wolf coding , Wyner -Ziv coding and
various other forms of multiterminal source coding ) , has recently become a very active
research area .
In this thesis , we first design a practical coding scheme for the quadratic Gaussian
Wyner -Ziv problem , because in this special case , no rate loss is suffered due to
the unavailability of the side information at the encoder . In order to approach the
Wyner -Ziv distortion limit D ? ?W Z (R ) , the trellis coded quantization (TCQ ) technique
is employed to quantize the source X , and irregular LDPC code is used to implement
Slepian -Wolf coding of the quantized source input Q (X ) given the side information
Y at the decoder . An optimal non -linear estimator is devised at the joint decoder
to compute the conditional mean of the source X given the dequantized version of
Q (X ) and the side information Y . Assuming ideal Slepian -Wolf coding , our scheme
performs only 0 .2 dB away from the Wyner -Ziv limit D ? ?W Z (R ) at high rate , which
mirrors the performance of entropy -coded TCQ in classic source coding . Practical
designs perform 0 .83 dB away from D ? ?W Z (R ) at medium rates . With 2 -D trellis -coded
vector quantization , the performance gap to D ? ?W Z (R ) is only 0 .66 dB at 1 .0 b /s and
0 .47 dB at 3 .3 b /s .
We then extend the proposed Wyner -Ziv coding scheme to the quadratic Gaussian
multiterminal source coding problem with two encoders . Both direct and indirect
settings of multiterminal source coding are considered . An asymmetric code design
containing one classical source coding component and one Wyner -Ziv coding component
is first introduced and shown to be able to approach the corner points on the
theoretically achievable limits in both settings . To approach any point on the theoretically
achievable limits , a second approach based on source splitting is then described .
One classical source coding component , two Wyner -Ziv coding components , and a
linear estimator are employed in this design . Proofs are provided to show the achievability
of any point on the theoretical limits in both settings by assuming that both
the source coding and the Wyner -Ziv coding components are optimal . The performance
of practical schemes is only 0 .15 b /s away from the theoretical limits for the
asymmetric approach , and up to 0 .30 b /s away from the limits for the source splitting
approach . |