Topic
Jamming
About: Jamming is a research topic. Over the lifetime, 9146 publications have been published within this topic receiving 106690 citations.
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TL;DR: This paper investigates methods for reducing the likelihood that a message transmitted between two multi-antenna nodes is intercepted by an undetected eavesdropper, and uses signal-to-interference-plus-noise-ratio (SINR) as a performance metric.
Abstract: In this paper, we investigate methods for reducing the likelihood that a message transmitted between two multi-antenna nodes is intercepted by an undetected eavesdropper. In particular, we focus on the judicious transmission of artificial interference to mask the desired signal at the time it is broadcast. Unlike previous work that assumes some prior knowledge of the eavesdropper's channel and focuses on maximizing secrecy capacity, we consider the case where no information regarding the eavesdropper is available, and we use signal-to-interference-plus-noise-ratio (SINR) as our performance metric. Specifically, we focus on the problem of maximizing the amount of power available to broadcast a jamming signal intended to hide the desired signal from a potential eavesdropper, while maintaining a prespecified SINR at the desired receiver. The jamming signal is designed to be orthogonal to the information signal when it reaches the desired receiver, assuming both the receiver and the eavesdropper employ optimal beamformers and possess exact channel state information (CSI). In practice, the assumption of perfect CSI at the transmitter is often difficult to justify. Therefore, we also study the resulting performance degradation due to the presence of imperfect CSI, and we present robust beamforming schemes that recover a large fraction of the performance in the perfect CSI case. Numerical simulations verify our analytical performance predictions, and illustrate the benefit of the robust beamforming schemes.
455 citations
TL;DR: It is shown, using theory and numerical simulation, that the landscape is much rougher than is classically assumed and undergoes a 'roughness transition' to fractal basins, which brings about isostaticity and marginal stability on approaching jamming.
Abstract: Glasses are amorphous solids whose constituent particles are caged by their neighbors and thus cannot flow. This sluggishness is often ascribed to the free energy landscape containing multiple minima (basins) separated by high barriers. Here we show, using theory and numerical simulation, that the landscape is much rougher than is classically assumed. Deep in the glass, it undergoes a "roughness transition" to fractal basins. This brings about isostaticity at jamming and marginality of glassy states near jamming. Critical exponents for the basin width, the weak force distribution, and the spatial spread of quasi-contacts at jamming can be analytically determined. Their value is found to be compatible with numerical observations. This advance therefore incorporates the jamming transition of granular materials into the framework of glass theory. Because temperature and pressure control which features of the landscape are experienced, glass mechanics and transport are expected to reflect the features of the topology we discuss here. Hitherto mysterious properties of low-temperature glasses could be explained by this approach.
441 citations
TL;DR: Simulation results show that the secrecy rate is dramatically increased when inactive nodes in the relay network participate in cooperativeJamming, and a GSVD-based cooperative jamming scheme is proposed that shows significant improvement in terms of secrecy rate compared to the approach without jamming.
Abstract: Secure communications can be impeded by eavesdroppers in conventional relay systems. This paper proposes cooperative jamming strategies for two-hop relay networks where the eavesdropper can wiretap the relay channels in both hops. In these approaches, the normally inactive nodes in the relay network can be used as cooperative jamming sources to confuse the eavesdropper. Linear precoding schemes are investigated for two scenarios where single or multiple data streams are transmitted via a decode-and-forward (DF) relay, under the assumption that global channel state information (CSI) is available. For the case of single data stream transmission, we derive closed-form jamming beamformers and the corresponding optimal power allocation. Generalized singular value decomposition (GSVD)-based secure relaying schemes are proposed for the transmission of multiple data streams. The optimal power allocation is found for the GSVD relaying scheme via geometric programming. Based on this result, a GSVD-based cooperative jamming scheme is proposed that shows significant improvement in terms of secrecy rate compared to the approach without jamming. Furthermore, the case involving an eavesdropper with unknown CSI is also investigated in this paper. Simulation results show that the secrecy rate is dramatically increased when inactive nodes in the relay network participate in cooperative jamming.
373 citations
TL;DR: In this article, two continuum models of traffic are proposed to describe the jamming transition in traffic flow on a highway, one is described by the partial differential equations and the other is the discrete lattice version.
Abstract: Continuum models of traffic are proposed to describe the jamming transition in traffic flow on a highway. They are the simplified versions of the hydrodynamic model of traffic. Two continuum models are presented: one is described by the partial differential equations and the other is the discrete lattice version. The linear stability theory and the nonlinear analysis are applied to the continuum models. The modified Korteweg–de Vries equation (KdV) near the critical point is derived using the reduction perturbation method. It is shown that the jamming transition and the density wave in the congested traffic flow are described by the modified KdV equation. The solutions of the KdV equations obtained from the two models are compared with that of the optimal velocity model (car following model).
368 citations
Book•
30 Nov 2003
TL;DR: This newly revised and greatly expanded edition of the popular Artech House book, Modern Communications Jamming Principles and Techniques, provides an up-to-date, exhaustive treatment of the techniques and methods available to create countermeasures against anti-jam, over-the-air communications.
Abstract: This newly revised and greatly expanded edition of the popular Artech House book, Modern Communications Jamming Principles and Techniques, provides an up-to-date, exhaustive treatment of the techniques and methods available to create countermeasures against anti-jam, over-the-air communications. The Second Edition features a wealth of new material on urban warfare, including a computer simulation of EW architecture alternatives for land-based forces based on urban constraints. The new edition also includes an expanded section on time-hopped spread spectrum communications, more details on modern communication system technologies such as CDMA and OFDM, and an in-depth discussion on sources of urban noise. This practical resource is focused on showing you how to design and build jammers specifically targeted at spread spectrum, anti-jam communications. Moreover, you find assistance in evaluating the expected performance of jamming systems against modern communications systems, and discover the best waveform to use to counter communication systems designed to be effective in jamming environments. While mathematical derivations in general are avoided, the book presents error rate performance equations for most modern digital anti-jam communication systems.
367 citations