Group Of Eavesdroppers Research Articles

Enhancing Security in Cognitive Radio Multicast Networks Using Interference Power

In this paper, security issue in multiple input multiple output (MIMO) multicasting system has been analyzed in the presence of a group of eavesdroppers in cognitive radio networks (CRNs). Primary base station (PBS) and secondary base station (SBS) communicate with multiple primary and secondary receivers, respectively via a precoding relay having multiple antennas. At first, considering interference the secrecy multicast capacity at the primary receivers (PRs) and the secondary receivers (SRs) has been calculated and investigated the impact of interferences on it. Then, the zero-forcing (ZF) precoding technique at the relay has been employed which enhances the secrecy multicast capacity at the PRs and SRs by zeroing the impact of interference on each other. Secondly, the existing constructive interference energy of the communication medium employing selective precoding (SP) technique at the relay has been used to improve the secrecy multicast capacity of the PRs and SRs. Finally, phase alignment precoding (PAP) technique at the relay has been introduced which uses the destructive part of interference for further increase in the secrecy multicast capacity at the PRs and SRs. It is observed that among the three precoding techniques, the best performance is achieved by using the PAP at the relay in terms of secrecy multicast capacity and secure outage probability analysis. This is due to the fact that PAP technique at the relay not only uses the constructive interference part but also it rotates the destructive interference part in such a way that the resulting interference is always instantaneously constructive. So using these precoding relays interference power can be used to enhance system performance without increasing base station power.

On Secure VLC Systems With Spatially Random Terminals

This letter investigates the secrecy performance of a visible light communication (VLC) system with a legitimate receiver and a group of eavesdroppers. Considering the randomness of the locations of the legitimate receiver and the eavesdroppers, the statistical characteristics of the signal-to-noise ratio over the VLC downlinks are characterized; then, we derive the closed-form analytical expressions for secrecy outage probability and the average secrecy capacity by using stochastic geometry method. Finally, simulations are carried on to verify our proposed analytical models.

Degraded Compound Multi-Receiver Wiretap Channels

We study the degraded compound multi-receiver wiretap channel (DCMRWC). DCMRWC consists of two groups of users and a group of eavesdroppers, where, if we pick an arbitrary user from each group of users and an arbitrary eavesdropper, they satisfy a certain Markov chain. We study two different communication scenarios for this channel. In the first scenario, the transmitter wants to send a confidential message to users in the first (stronger) group and a different confidential message to users in the second (weaker) group, where both messages need to be kept confidential from the eavesdroppers. For this scenario, we assume that there is only one eavesdropper. We obtain the secrecy capacity region for the discrete memoryless channel model, the parallel channel model, and the Gaussian parallel channel model. For the Gaussian multiple-input multiple-output (MIMO) channel model, we obtain the secrecy capacity region when there is only one user in the second group. In the second scenario we study, the transmitter sends a confidential message to users in the first group which needs to be kept confidential from the second group of users and the eavesdroppers. Moreover, the transmitter sends a different confidential message to users in the second group which needs to be kept confidential only from the eavesdroppers. For this scenario, we do not put any restriction on the number of eavesdroppers. As in the first scenario, we obtain the secrecy capacity region for the discrete memoryless channel model, the parallel channel model, and the Gaussian parallel channel model. For the Gaussian MIMO channel model, we establish the secrecy capacity region when there is only one user in the second group.

Secure broadcasting using multiple antennas

We consider three different secure broadcasting scenarios: i) Broadcast channels with common and confidential messages (BCC), ii) multi-receiver wiretap channels with public and confidential messages, and iii) compound wiretap channels. The BCC is a broadcast channel with two users, where in addition to the common message sent to both users, a private message, which needs to be kept hidden as much as possible from the other user, is sent to each user. In this model, each user treats the other user as an eavesdropper. The multi-receiver wiretap channel is a broadcast channel with two legitimate users and an external eavesdropper, where the transmitter sends a pair of public and confidential messages to each legitimate user. Although there is no secrecy concern about the public messages, the confidential messages need to be kept perfectly secret from the eavesdropper. The compound wiretap channel is a compound broadcast channel with a group of legitimate users and a group of eavesdroppers. In this model, the transmitter sends a common confidential message to the legitimate users, and this confidential message needs to be kept perfectly secret from all eavesdroppers. In this paper, we provide a survey of the existing information-theoretic results for these three forms of secure broadcasting problems, with a closer look at the Gaussian multiple-input multiple-output (MIMO) channel models. We also present the existing results for the more general discrete memory-less channel models, as they are often the first step in obtaining the capacity results for the corresponding Gaussian MIMO channel models.

The Diction of Strange Interlude

actually rests, not on reality but on convention, as all technics at bottom do. When you go to a play, you know perfectly well (if you bother to think about it) that what happens on the stage is aimed at you and your fellows in the audience. But by the so-called realistic convention the actors ignore your presence and the action proceeds, in theory, as if you were not there at all. Every word spoken on the stage is meant for the ears of the audience, but it would never do to address those ears directly. The players ostensibly talk only to each other, and the audience are supposed to be a group of eavesdroppers who overhear what the players say. Along with this convention go others. Above all, the characters in a play must talk naturally. That is to say, they must use the kind of language natural to them in everyday conversation, since, by convention, their speeches are private give and take, not public oratory. Needless to say, Shakespeare and his age had a set of conventions very different from those I have just described. The Elizabethans did not ignore the audience, even in theory. Oratorical flights, appropriate to speakers addressing large assemblies, abound in Elizabethan plays, and soliloquies and asides, banned from the modern stage because they are direct communications from actor to audience, were in excellent dramatic standing in sixteenth century England. But, naturally, much of the business was between actor and actor, not between actor and audience, and in these parts of the dialogue the audience was out of it and was supposed to overhear rather than hear, precisely as in our theater of today. In sum, the chief difference between the two stages lies in the matter of consistency. We insist that the same technic be applied throughout; they shifted from one technic to the other at will in the same play. It has often been remarked that Eugene O'Neill, in Strange Interlude and elsewhere, turns away from the modern technic and goes back to the Elizabethan technic. The multiplicity of his scenes (or acts, if you will), and his free use of asides, are obvious and striking examples of this reversion. But the chief point, as we have seen, is that of consistency, and in the present study I will examine the language of Strange Interlude with a view to finding out, first, whether 19