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ETH Series in Information Theory and its Applications,
Vol. 9
edited by Amos Lapidoth
Tibor Keresztfalvi
Some Data are More Important than Others
1st edition 2018. XIV, 110 pages, € 64,00.
ISBN
978-3-86628-625-2
Abstract
This thesis is comprised of two parts. Both parts
study informationtheoretic aspects of joint
transmission of data of different levels of sensitivity. The more sensitive
data is better protected than the less sensitive data. In the first part the
data streams have different robustness criteria with respect to variations of
the underlying channel model, and in the second part, the data streams have
different decoding error requirements.
In the first part, we establish the deterministic-code
capacity region of a network with one transmitter and two receivers: an
“ordinary receiver” and a “robust receiver.” The channel to the ordinary
receiver is a given (known) discrete memoryless channel, whereas the channel to
the robust receiver is an arbitrarily varying channel. Both receivers are
required to decode the “common message” (the more sensitive data), whereas only
the ordinary receiver is required to decode the “private message” (the less
sensitive data).
In the second part, two independent data streams are
to be transmitted over a noisy discrete memoryless channel: the “zero-error
stream” (the more sensitive data) and the “rare-error stream” (the less
sensitive data). Errors are tolerated only in the rare-error stream, provided
that their probability tends to zero as the blocklength
tends to infinity.
If the encoder has access to a noiseless feedback link
from the output of the channel, the rate of the zero-error stream cannot, of
course, exceed the channel’s zero-error feedback capacity, and nor can the sum
of the streams’ rates exceed the channel’s Shannon capacity. Using a suitable
feedback coding scheme, these necessary conditions are shown to characterize
all the achievable rate pairs and thus the multiplexing capacity region with
feedback. Planning for the worst—as is needed to achieve zero-error
communication—and planning for the true channel— as is needed to communicate
near the Shannon limit—are thus not incompatible.
If the encoder has no feedback, computing the
multiplexing capacity region is at least as hard as computing the zero-error
capacity of a discrete memoryless channel. We present some outer bounds that
show that feedback may be beneficial for the multiplexing problem even on
channels on which it does not increase the zero-error capacity.
Keywords:
Unequal error protection, arbitrarily varying channel, broadcast channel,
degraded message set, robust communications, feedback, multiplexing, Shannon
capacity, zero-error capacity.
About the
Author
Tibor Keresztfalvi was born in Budapest, Hungary on
24 September 1991. He attended elementary school in Arlesheim,
Switzerland, and high school in Budapest, Hungary with a specialization in
mathematics. During this time he attended various national mathematic
competitions in Hungary.
In 2010, after graduating high school, he moved back
to Switzerland and entered ETH Zurich to study Electrical Engineering and
Information Technology. There he obtained his Bachelor degree in 2013.
He continued his studies with focus on communications
at ETH Zurich. During that time he spent an exchange semester at University of
Pennsylvania, Philadelphia where in addition to his field of specialization he
took courses at the Wharton Business School. He also became interested in
information theory and wrote his master thesis in this field. He obtained his
masters degree in 2013.
Since 2015, he has been a PhD candidate and full
research assistant at the Signal and Information Processing Laboratory (ISI) at
ETH Zurich under the supervision of Prof. Dr. Amos Lapidoth.
Reihe "ETH
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