Browsing by Author "Loyka, S."

Now showing items 1-19 of 19

    • Article  

      An Algorithm for Global Maximization of Secrecy Rates in Gaussian MIMO Wiretap Channels 

      Loyka, S.; Charalambous, Charalambos D. (2015)
      Optimal signaling for secrecy rate maximization in Gaussian MIMO wiretap channels is considered. While this channel has attracted a significant attention recently and a number of results have been obtained, including the ...
    • Conference Object  

      The capacity of unstable dynamical systems-interaction of control and information transmission 

      Charalambous, Charalambos D.; Kourtellaris, C. K.; Loyka, S.; Tzortzis, I. (Institute of Electrical and Electronics Engineers Inc., 2017)
      Feedback capacity is extended beyond classical communication channels, to stochastic dynamical systems, which may correspond to unstable control systems or unstable communication channels, subject to average cost constraints ...
    • Conference Object  

      Ergodic capacity under channel distribution uncertainty 

      Loyka, S.; Charalambous, Charalambos D.; Ioannou, I. (Institute of Electrical and Electronics Engineers Inc., 2014)
      The impact of channel distribution uncertainty on the performance of fading channels is studied. The compound capacity of a class of ergodic fading channels subject to channel distribution uncertainty is obtained, for ...
    • Conference Object  

      Extremum problems with total variation distance 

      Charalambous, Charalambos D.; Tzortzis, I.; Loyka, S.; Charalambous, T. (Institute of Electrical and Electronics Engineers Inc., 2013)
      The aim of this paper is to investigate extremum problems with pay-off the total variational distance metric subject to linear functional constraints both defined on the space of probability measures, as well as related ...
    • Article  

      Extremum problems with total variation distance and their applications 

      Charalambous, Charalambos D.; Tzortzis, I.; Loyka, S.; Charalambous, T. (2014)
      The aim of this paper is to investigate extremum problems with pay-off being the total variation distance metric defined on the space of probability measures, subject to linear functional constraints on the space of ...
    • Conference Object  

      Feedback does not increase the capacity of compound channels with additive noise 

      Loyka, S.; Charalambous, Charalambos D. (Institute of Electrical and Electronics Engineers Inc., 2016)
      A discrete compound channel with memory is considered, where no stationarity, ergodicity or information stability is required, and where the uncertainty set can be arbitrary. When the discrete noise is additive but otherwise ...
    • Conference Object  

      Further results on optimal signaling over secure MIMO channels 

      Loyka, S.; Charalambous, Charalambos D. (2013)
      Optimal signalling over the wire-tap MIMO Gaussian channel is studied under the total transmit power constraint. The recent results are extended in several directions, including a rank-deficient solution for the optimal ...
    • Article  

      A General Formula for Compound Channel Capacity 

      Loyka, S.; Charalambous, Charalambos D. (2016)
      A general formula, for the capacity of arbitrary compound channels with the receiver channel state information, is obtained using the information density approach. No assumptions of ergodicity, stationarity, or information ...
    • Conference Object  

      A general formula for compound channel capacity 

      Loyka, S.; Charalambous, Charalambos D. (Institute of Electrical and Electronics Engineers Inc., 2015)
      A general formula for the capacity of arbitrary compound channels, which are not necessarily ergodic, stationary or information-stable, is obtained using the information density approach. A direct (constructive) proof is ...
    • Article  

      Novel Matrix Singular Value Inequalities and Their Applications to Uncertain MIMO Channels 

      Loyka, S.; Charalambous, Charalambos D. (2015)
      Novel matrix singular value inequalities are established for a sum/product of three matrices. Their application to the uncertain (compound) multiple-input multiple-output (MIMO) channel subject to normed additive uncertainty ...
    • Conference Object  

      On optimal signaling over secure MIMO channels 

      Loyka, S.; Charalambous, Charalambos D. (2012)
      Optimal signalling over the wire-tap MIMO Gaussian channel is studied under the total transmit power constraint. A direct proof of the necessary condition of optimality (signaling on the positive directions of the difference ...
    • Conference Object  

      On the capacity of a class of MIMO channels subject to normed uncertainty 

      Loyka, S.; Charalambous, Charalambos D. (2008)
      The compound capacity of uncertain MIMO channels is considered, when the channel is modeled by a class described by an induced norm constraint. Within this framework, two types of classes are investigated, namely, additive ...
    • Article  

      On the compound capacity of a class of MIMO channels subject to normed uncertainty 

      Loyka, S.; Charalambous, Charalambos D. (2012)
      The compound capacity of uncertain multiple-input multiple-output channels is considered, when the channel is modeled by a class described by a (known) nominal channel and a constrained-norm (unknown) uncertainty. Within ...
    • Article  

      Optimal signaling for secure communications over Gaussian MIMO wiretap channels 

      Loyka, S.; Charalambous, Charalambos D. (2016)
      Optimal signaling over the Gaussian multiple-input multiple-output wire-tap channel is studied under the total transmit power constraint. A closed-form solution for an optimal transmit covariance matrix is obtained when ...
    • Article  

      Outage probability under channel distribution uncertainty 

      Ioannou, I.; Charalambous, Charalambos D.; Loyka, S. (2012)
      Outage probability and capacity of a class of block-fading MIMO channels are considered under partial channel distribution information. Specifically, the channel or its distribution is not known but the latter is known to ...
    • Conference Object  

      Outage probability under channel distribution uncertainty 

      Ioannou, I.; Charalambous, Charalambos D.; Loyka, S. (2011)
      Outage probability of a class of block-fading (MIMO) channels is considered under channel distribution uncertainty, when the channel or its distribution are not known but the latter is known to belong to a class of ...
    • Conference Object  

      Rank-deficient solutions for optimal signaling over secure MIMO channels 

      Loyka, S.; Charalambous, Charalambos D. (Institute of Electrical and Electronics Engineers Inc., 2014)
      Capacity-achieving signaling strategies for the Gaussian wiretap MIMO channel are investigated without the degradedness assumption. In addition to known solutions, a number of new rank-deficient solutions for the optimal ...
    • Article  

      Rank-Deficient Solutions for Optimal Signaling over Wiretap MIMO Channels 

      Loyka, S.; Charalambous, Charalambos D. (2016)
      Capacity-achieving signaling strategies for the Gaussian wiretap multiple-input multple-output (MIMO) channel are investigated without the degradedness assumption. In addition to known solutions, a number of new rank-deficient ...
    • Book Chapter  

      Secrecy Rate Maximization in Gaussian MIMO Wiretap Channels 

      Loyka, S.; Charalambous, Charalambos D. (Cambridge University Press, 2017)
      Secrecy rate maximization in Gaussian MIMO wiretap channels is considered. While the optimality of Gaussian signaling and a general expression for the secrecy capacity have been well established, closed-form solutions for ...