DSC using Convolutional Codes
DSC Using Turbo Codes
Other DSC Work
(Last modified November 2001. For more recent work, refer to the Wyner-Ziv
Coding of Video webpage)
a communication system with two correlated signals, X and Y
(see Figure 1). Assume that
X and Y come from two separate sources that cannot
with each other, that is, the signals are encoded independently or are
“distributed”. The receiver,
on the other hand, can see both encoded signals and can perform joint
A sensor system composed of low-complexity spatially separated sensor
sending correlated information to a central processing receiver, is an
example of such system. What is the minimum encoding rate required such
that X and Y can still be recovered perfectly?
If a joint encoder
a joint decoder are used, the minimum combined rate for probability of
decoding error to approach zero is simply the joint entropy H(X,Y).
Surprisingly, as proven by Slepian and Wolf in 1973 , a combined
of H(X,Y) is sufficient even if the correlated signals
encoded separately. According
to the Slepian-Wolf coding theorem, the achievable rate region for
sources X and Y is given by
is an encouraging conceptual basis for distributed source coding but
today the theoretical limits have not yet been achieved, nor have been
closely approached, by practical applications.
In , Pradhan and Ramchandran demonstrate the intuition behind
coding by providing a solution for X and Y separated by
maximum Hamming distance.
Pradhan and Ramchandran also developed the DISCUS (Distributed Source
Using Syndromes) method .
In DISCUS, instead of sending the codeword representing X, the
of the codeword coset is sent and the receiver decodes by choosing the
codeword in the given coset that is closest to Y.
DISCUS, with trellis and lattice encoding, was used in their study to
correlated Gaussian sources.
However, it was not shown that the techniques clearly approached the
bound. The objective of this
project is to find practical coding techniques that can perform close
the Slepian-Wolf achievable rate region and would be effective for
types of X and Y correlation.