Karim Abulmakarem Mohamed Khalil

Delay-Limited Secure Communication Over Fading Channels / Karim Abulmakarem Mohamed Khalil - 2009 - 59 p. ill. 21 cm.

Supervisor: Moustafa Youssef

Thesis (M.A.)—Nile University, Egypt, 2009 .

"Includes bibliographical references"

Contents:
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 The Wireless Channel . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Previous Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 System Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.4 Outline and Contribution . . . . . . . . . . . . . . . . . . . . . . . 10
2. Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.1 Physical Layer Security . . . . . . . . . . . . . . . . . . . . . . . . 12
2.2 Delay Limited Communication . . . . . . . . . . . . . . . . . . . . 14
2.2.1 Ergodic vs Delay Limited Setting: Capacity and Power Control 15
2.2.2 Transmitter CSI . . . . . . . . . . . . . . . . . . . . . . . . 16
viii
3. Full Transmitter CSI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.1 Upper Bound on the Delay Limited Secrecy Capacity . . . . . . . . 18
3.2 Achievable Delay Limited Secrecy Rate . . . . . . . . . . . . . . . . 19
3.2.1 Achievability Proof . . . . . . . . . . . . . . . . . . . . . . . 20
3.2.2 Remarks on the achievability scheme . . . . . . . . . . . . . 27
3.3 Asymptotic Optimality of the Achievable Rate . . . . . . . . . . . 27
3.4 Numerical Results . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
4. Only Main Channel CSI . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4.1 Upper Bound on the Delay Limited Secrecy Capacity . . . . . . . . 30
4.2 Achievable Delay Limited Secrecy Rate . . . . . . . . . . . . . . . . 31
4.2.1 Proof of the Achievable Scheme . . . . . . . . . . . . . . . . 32
4.3 Numerical Results . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
5. Conclusions and Future Work . . . . . . . . . . . . . . . . . . . . . . . . 38
Appendices:
A. Random Binning Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
B. Ergodic Secrecy Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . 42
B.1 Full Transmitter CSI . . . . . . . . . . . . . . . . . . . . . . . . . . 42
B.2 Only Main Channel CSI . . . . . . . . . . . . . . . . . . . . . . . . 43
Bibliography . . . .

Abstract:
Many wireless applications are limited by different forms of delay constraints.
These applications range from the most basic voice communication to the more demanding
multimedia streaming. However, due to its broadcast nature, the wireless
channel is vulnerable to eavesdropping and other security threats. Therefore, techniques
that satisfy both the delay limitation and the confidentiality requirement are
of definite interest. This motivates our analysis of the fundamental (information theoretic)
limits of secure communication over fading channels subject to strict deadlines.
In this thesis, we study the delay limited secrecy capacity of the flat fading channel
under two different assumptions on the available transmitter channel state information
(CSI). The first scenario assumes perfect prior knowledge of both the main and
eavesdropper channel gains. Here, upper and lower bounds on the delay limited secrecy
capacity are derived, and shown to be tight in the high signal-to-noise ratio
(SNR) regime. In the second scenario, only the main channel CSI is assumed to
be available at the transmitter where, remarkably, we establish the achievability of
a non-zero delay-limited secure rate, for a wide class of channel distributions, with
a high probability. In the two cases, our achievability arguments are based on a
novel two-stage key-sharing approach that overcomes the secrecy outage phenomenon
observed in earlier works.


Text in English, abstracts in English.


Wireless Technologies


Dissertation, Academic

005