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SUMMARY:Filter Design with Secrecy Constraints - Dr Miguel R. D. Rodrigues
 \, University of Porto
DTSTART:20090225T141500Z
DTEND:20090225T151500Z
UID:TALK16943@talks.cam.ac.uk
CONTACT:Rachel Fogg
DESCRIPTION:The issues of privacy and security in wireless communication n
 etworks have taken on an increasingly important role as these networks con
 tinue to flourish worldwide. Traditionally\, security is viewed as an inde
 pendent feature with little or no relation to the remaining data communica
 tion tasks and\, therefore\, state-of-the-art cryptographic  algorithms ar
 e insensitive to the physical nature of the wireless medium.\nThis talk in
 troduces yet another physical-layer security paradigm\, based on an estima
 tion-theoretic problem formulation rather than the information-theoretic o
 ne: We consider the problem of filter design with secrecy constraints in t
 he classical wiretap scenario\, where two legitimate parties communicate i
 n the presence of an eavesdropper. In particular\, we consider the design 
 of transmit and receive filters that minimize the mean-squared error (MSE)
  between the legitimate parties whilst guaranteeing a certain eavesdropper
  MSE level subject to a total average power constraint\, in the situation 
 where the main channel and the wiretap channel consist of a bank of parall
 el independent degraded Gaussian channels (a scenario representative of or
 thogonal frequency division multiplexing (OFDM) communications systems).\n
 The traditional problem of filter design for point-to-point communications
  systems can be easily cast into the framework of convex optimization theo
 ry by using standard tools from majorization theory or matrix-monotone fun
 ctions. In contrast\, the problem of filter design with secrecy constraint
 s is much more complex. We address this problem by putting forth a novel m
 athematical framework\, revolving around the notions of D-sets\, D-functio
 ns and D-optimization problems\, that enables the transformation of the or
 iginal optimization problem into a convex one. We derive the form of the o
 ptimal receive filter and the optimal transmit filter. We also derive the 
 form of the optimal filters in the asymptotic regimes of low and high avai
 lable power. We will complement theoretical insight with various numerical
  results. \nThis represents joint work with João Xavier from the Technica
 l University of Lisbon\, Portugal.\n\n
LOCATION:LR5\, Engineering\, Department of
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