The prominence of the wireless communication has been urging the monotonically increasing demand of security and privacy. In wireless systems, the notion of perfect secrecy of information with respect to illegitimate nodes can be ensured via physical layer security (PLS) techniques. Unfortunately, they can be made less effective if sourceeavesdropper wiretap channel is better than the main sour...

Reliable communication imposes an upper limit on the achievable rate, namely the Shannon capacity. Wyner’s wiretap coding, which ensures a security constraint also, in addition to reliability, results in decrease of the achievable rate. To mitigate the loss in the secrecy rate, we propose a coding scheme where we use sufficiently old messages as key and for this scheme prove that multiple messa...

Title of dissertation: ALIGNMENT AND COOPERATION FOR SECRECY IN MULTI-USER CHANNELS Raef Bassily Doctor of Philosophy, 2011 Dissertation directed by: Professor Şennur Ulukuş Department of Electrical and Computer Engineering The study of the physical layer has offered a new perspective to the problem of communication security. This led to the development of a vast set of ideas and techniques roo...

Motivated by the two-user beamforming in multiantenna interference channels, we characterize the upper boundary of the achievable single-user gain-region. The eigenvector corresponding to the maximum eigenvalue of the weighted sum of Hermitian forms of channel vectors is shown to achieve all points on the boundary in some given direction. Thereby, we solve three different beamforming problems, ...

Anonymous monitoring of transmissions in a wireless network by eavesdroppers can provide critical information about the data flows in the network. It is, therefore, necessary to design network protocols that maintain secrecy of routes from eavesdroppers. In this work, we present a mathematical formulation of route secrecy when eavesdroppers observe transmission epochs of nodes. We propose sched...

in this paper, we consider a cooperative cognitive radio network in which there is an ofdm primary link and multiple single carrier secondary links.the primary link is required to maintain its secrecy rate above a predefined threshold. if the secrecy rate requirement is not satisfied, the secondary system help primary link to maintain its secrecy rate requirement. in doing so, the secondary trans...

This paper concerns maximizing the minimum achievable secrecy rate of a two-way relay network in the presence of an eavesdropper, in which two nodes aim to exchange messages in two hops, using a multi-antenna relay. Throughout the first hop, the two nodes simultaneously transmit their messages to the relay. In the second hop, the relay broadcasts a combination of the received information to the...

This study deals with opportunistic relay selection in cooperative networks with secrecy constraints, where an eavesdropper node tries to overhead the source message. Previously reported relay selection techniques are optimised for non-eavesdropper environments and cannot ensure security. Two new opportunistic relay selection techniques, which incorporate the quality of the relay-eavesdropper l...

The secrecy capacity region for the K-receiver degraded broadcast channel (BC) is given for confidential messages sent to the receivers and to be kept secret from an external wiretapper. Superposition coding and Wyner’s random code partitioning are used to show the achievable rate tuples. Error probability analysis and equivocation calculation are also provided. In the converse proof, a new def...

This paper considers an artificial noise (AN)-aided transmit design for multi-user MIMO systems with integrated services. Specifically, two sorts of service messages are combined and served simultaneously: one multicast message intended for all receivers and one confidential message intended for only one receiver and required to be perfectly secure from other unauthorized receivers. Our interes...