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— Given a multiple-antenna source and a multiple-antenna destination, a multiple-antenna relay between the source and the destination is desirable under useful circumstances. A non-regenerative multiple-antenna relay, also called non-regenerative MIMO (multi-input multi-output) relay, is designed to optimize the capacity between the source and the(More)
The focus of this paper is an information-theoretic study of retransmission protocols for reliable packet communication under a secrecy constraint. The <i>h</i>ybrid <i>a</i>utomatic <i>r</i>etransmission re<i>q</i>uest (HARQ) protocol is revisited for a block-fading wiretap channel. Here, two legitimate users communicate over a block-fading channel in the(More)
Wireless communication is susceptible to eavesdropping attacks because of its broadcast nature. This paper illustrates how interference can be used to counter eavesdropping and assist secrecy. In particular, a wiretap channel with a helping interferer (WT-HI) is considered. Here, a transmitter sends a confidential message to its intended receiver in the(More)
In this paper, we develop a unified framework for linear nonregenerative multicarrier multiple-input multiple-output (MIMO) relay communications in the absence of the direct source-destination link. This unified framework classifies most commonly used design objectives such as the minimal mean-square error and the maximal mutual information into two(More)
Due to the broadcast nature of the wireless medium, wireless communication is susceptible to adversarial eavesdropping. This paper describes how eavesdropping can potentially be defeated by exploiting the superposition nature of the wireless medium. A Gaussian wire-tap channel with a helping interferer (WTC-HI) is considered in which a transmitter sends(More)
This article presents a variant of sigma-point Kalman filters family called square-root spherical simplex unscented Kalman filter for online Bayesian recursive estimation of the state and parameter of nonlinear systems with non-Gaussian statistics. The algorithm consists of a better-behaved spherical simplex unscented transformation to build the sigma point(More)
This paper considers the problem of secret communication over a multiple access channel with generalized feedback. Two trusted users send independent confidential messages to an intended receiver, in the presence of a passive eavesdropper. In this setting, an active cooperation between two trusted users is enabled through using channel feedback in order to(More)
In this correspondence, we show that the uniform throughput capacity of an ultra-wideband (UWB) power-constrained ad hoc network is given by , where is the per-node power constraint, is the fading exponent of radio signal and is the number of nodes randomly distributed inside a disk of unit area. This is a stronger result than the upper bound and the lower(More)
We study the block fading wire-tap channel, where a transmitter sends confidential messages to a legitimate receiver over a block fading channel in the presence of an eavesdropper, which listens to the transmission through another independent block fading channel. We assume that the transmitter has no channel state information (CSI) available from either(More)