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The committee hosted a
Student Roundtable Research Discussion and Lunch at the CISS conference at
Johns Hopkins University on Wednesday, March 14. Approximately 60 students
attended the lunch and enjoyed pizza and soda. Six discussion topics were
chosen and each discussion was led by a student discussion leader. The
discussion topics and leaders were:
Table #1:
Joint Source-Channel Coding for Wireless Networks
Leader:
Deniz Gunduz (Polytechnic)
Shannon's source-channel separation theorem is
one of the most fundamental results of information theory (its proof can be
found in most information theory textbooks). It leads to the division of
source and channel coding subproblems without losing the end-to-end
performance. However, there are certain limitations to this result, which
were the main discussion points of our table.
We first talked about the scenario of transmitting a Gaussian source over a
slow-fading wireless MIMO channel where only the receiver has channel state
information. In this scenario, the separation theorem fails due to the non-ergodicity
of the channel. We talked about the existing results and possible
extensions.
Next, we talked about multi-user networks, where there is no general
source-channel separation theorem. We talked about certain special scenarios
for which separation can be shown to be optimal, and others where separation
is shown to be strictly suboptimal.
While it seems that a comprehensive tutorial on joint source-channel coding
is lacking, and one including the most recent advances would be appreciated
by the students of the topic, following report of an NSF workshop held in
1999 can be helpful to understand the fundamental problems and directions:
Workshop Report: NSF Sponsored Workshop on Joint Source-Channel Coding, San
Diego, CA, Oct. 1999. (available at:
http://www.ee2.caltech.edu/Faculty/effros/JSCC/index.html)
Table #2:
Convex Optimization Applications
Leader:
Joydeep Acharya (Rutgers)
The topic at my table was convex optimization
applications. Since we didn't have too many participants, we could engage in
a one to one discussion about each person's research. We agreed that Prof
Stephen
Boyd's book is a good place to begin learning the subject. We then
discussed about utility function based resource allocation problems in
wireless settings. From there the discussion veered towards how interference
leads to non convexity of the utility functions and possible ways to
re-parameterize the objective and constraints to get rid of non-convexity.
For the beginner -
Prof Mung Chiang's site is a good place to see the summary of research
directions in convex optimization applications, results and open problems.
Table #3:
Detection and Estimation
Leader:
Anima Anandkumar (Cornell)
Good reference books for the topic : "An
introduction to signal detection and estimation " by Vincent Poor and
"Statistical signal processing" by Steven Kay.
References for distributed detection and estimation:
-
survey:
Distributed detection with multiple sensors I. Fundamentals Viswanathan,
R.; Varshney, P.K. Proceedings of the IEEE, Vol.85, Iss.1, Jan 1997
Pages:54-63
-
asymptotic
results: J. N. Tsitsiklis, "Decentralized detection by a large number of
sensors,". Math. Control Signals Syst., vol. 1, no. 2, pp. 167–182,
1988.
Table #4:
Distributed Source Coding
Leader:
Peiyu Tan (Lehigh)
Distributed source coding (DSC) , also known as
the Slepian-Wolf (SW) coding problem, concerns the separate encoding and
joint decoding of two or more correlated sources. DSC is related to the CEO
problem and is part of network information theory. The theoretical
foundation was proposed by Slepian and Wolf more than 30 years ago, but the
topics regarding practical applications of DSC become active recently, due
to the boosting interests in sensor networks and wireless video.
One fascinating aspect of this problem is that, without knowing the
instantaneous realization of the other source(s), the encoders can
nevertheless achieve, by exploiting the statistics of source correlation,
the same compression rate as joint encoding. Even more intriguing is that,
although the problem is by nature a source coding one, the solutions lie in
the technology of channel coding!
Milestones for distributed source coding:
-
D. Slepian and J.
K. Wolf, "Noiseless Coding of Correlated Information Sources," IEEE
Trans. Inform. Theory, pp. 471-480, July, 1973.
-
S. S. Pradhan and
K. Ramchandram, "Distributed Source Coding Using Syndromes (DISCUS):
Design and Construction," IEEE Tran. Inform. Theory, pp. 626-643, March,
2003.
Table #5:
Security and Cryptography
Leader:
Alvaro Cardenas (Berkeley)
Information security is a very broad research
field that usually focuses on providing services such as confidentiality,
integrity and availability. The tools the information security researchers
have developed to provide these services include cryptography, access
control, intrusion detection etc. However with the need to provide new
services such as anonymity, watermarking and traitor tracing, new adversary
models (adaptive adversaries and bounded storage models) and new research
paradigms such as quantum computation and quantum cryptography, the need to
develop new techniques based on information theory, signal processing and
game theory is evident.
In particular of interest to the information theory community is the new
conference on information theoretic security sponsored by the International
Association for Cryptologic Research (IACR). This year it is going to be
held after EUROCRYPT in Spain:
http://www.escet.urjc.es/~matemati/maribel/ICITS/ITS07.htm
Table #5:
MIMO Systems
Leader:
Mike Tinston (George Mason)
We had six people at the table and we all gave a
brief overview of our work, discussed topics in MIMO systems, shared some of
the references and who is doing what in the community, and ate a lot of
pizza. Each of the participants described their research and we had an
active exchange of information about the topic. We also recommended some
references for our particular areas of research. We should have had someone
jotting notes to remember what everybody said before we went our own ways
and focused our attention back on our own problems.
Thanks to all of the discussion leaders for making the event a success!
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