Jamming Effect Research Articles

Structured Light Transmission under Free Space Jamming: An Enhanced Mode Identification and Signal-to-Jamming Ratio Estimation Using Machine Learning

In this paper, we develop new classification and estimation algorithms in the context of free space optics (FSO) transmission. Firstly, a new classification algorithm is proposed to address efficiently the problem of identifying structured light modes under jamming effect. The proposed method exploits support vector machine (SVM) and the histogram of oriented gradients algorithm for the classification task within a specific range of signal-to-jamming ratio (SJR). The SVM model is trained and tested using experimental data generated using different modes of the structured light beam, including the 8-ary Laguerre Gaussian (LG), 8-ary superposition-LG, and 16-ary Hermite Gaussian (HG) formats. Secondly, a new algorithm is proposed using neural networks for the sake of predicting the value of SJR with promising results within the investigated range of values between −5 dB and 3 dB.

Research on Non-uniform Interrupted Sampling Repeater Jamming for Phase Coded Radar

Because of using correlation processing technology, it is difficult for traditional jamming patterns to achieve the desired jamming effect on phase coded radar. At present, the forward deception jamming of phase coded radar is mainly realized by uniform interrupted sampling repeater jamming (UISRJ). In order to solve the problem that the UISRJ can only produce a single and delayed false target, a kind of non-uniform interrupted sampling repeater jamming (NUISRJ) is proposed. The non-uniform sampling pulse train is generated through pseudo random sequence, and then sampled and forwarded to generate jamming signal, which is processed by radar pulse compression to form dense false targets. Combining the theoretical analysis and simulation results, it can be seen that the NUISRJ has the dual effects of suppressing jamming and spoofing jamming, and the distribution of false target string is more random, including the leading and lagging false target. The amplitude and coverage area of false targets group can be controlled by adjusting sampling pulse width and forwarding times to effectively implement jamming.

Increasing self-protection jammer efficiency using radar cross section adaptation

Increasing jamming effectiveness in self-protection electronic warfare systems is a crucial research area for air operations. Of all the factors affecting jamming performance, two parameters that increase jamming efficiency without changing the design parameters of radar and jammer systems are RCS and distance. Changing the distance between radar and target to increase the jamming effect is not sensible. Because disobeying the path for distance concern may ruin the operation aim. Adapting the RCS to the situation appears to be a suitable method to increase the jamming efficiency. In this study, a novel method is proposed for enhancement the jamming effectiveness by changing RCS appropriately. Hence, a heading calculator unit is integrated into the self-protection electronic warfare system. The heading calculator interacts with the radar warning receiver and jammer and points an appropriate heading direction during jamming. The heading variances are limited to as slight changes as possible.

Practical Jamming of a Commercial 5G Radio System at 3.6 GHz

Fifth-generation (5G) mobile technology has attracted interest from armed forces worldwide due to its many new possibilities for communication. Military operations may face threats in the electromagnetic spectrum, such as intentional jamming of the radio signals. Insights into the effect of jamming are needed to assess operational scenarios in which 5G is safe for military use. This paper presents a study based on an experiment of radio jamming on a commercial 5G system typical for deployments in mobile operators' networks. The prime objectives of the study were to identify a commercial 5G radio system's response to jamming and determine the jamming signal power needed to disrupt the 5G communication. The 5G base station was equipped with a massive Multiple-Input Multiple-Output (MIMO) antenna operating at the 3.6 GHz frequency band. The analysis results showed that the 5G radio system managed to adapt to the jamming by lowering the modulation and coding order until a breaking point was reached at which the interfering signal overcame the UE signal in the uplink, leading to the 5G connection being terminated. The required level of jamming signal strength needed to disrupt the communication agreed with the results from theoretical studies.

Investigation of granular capillary rising under vertical vibration

The phenomenon of granular capillary rising under vertical vibration provides a novel technical route for hoisting, transporting and collecting granular materials. However, there are still obvious deficiencies in the existing studies of the granular capillary rising behavior, especially the intensive investigation on the effects of gravitational acceleration, horizontal vibration component and particle size distribution are still lacking. To address these problems, the discrete element method is used to numerically simulate the granular capillary rising phenomenon under different operating conditions. The final capillary rising height and average capillary rising velocity of the granular matter are computed and analyzed based on the numerical simulations. The results show that the granular capillarity can also occur under low gravity conditions, and that the final capillary rising height and the average capillary rising velocity first increase and then decrease with the gravitational acceleration. It is also found that the final capillary rising height is insensitive to the variation of horizontal vibrational component, whereas the average capillary rising velocity increases with the augmentation of horizontal vibrational component. Compared with the mono-sized particles, the particles with the same mean size but having a Gaussian size distribution exhibit a maximal capillary rising height at a larger critical tube diameter. Meanwhile, the average capillary rising velocity of the particles having a Gaussian size distribution is faster in the tube diameter range where the granular capillary dynamics for both size distributions is dominated by the jamming effect.

A Missile Jamming Design for Aircraft Defence Using Infrared Automated Counter Measures

Infrared guided missiles possess a greater threat towards aircrafts in the scenario of defence. Securing aircrafts from such attacks requires an active directed infrared counter measure. Since DIRCM systems require the parameters of the missile signals to be known in advance, they suffer when attempted to be applied in real time. This paper proposes anInfrared Automated Counter Measures (IRACM) system with an equippedmissile alert equipment (MAE) capable of estimating the signal parameters once the signal is detected. Jamming is performed by which the missiles are subjected to miss the target along the field of vision by updating the jammer frequency based on the signal parameters. Since IR flashes in IRACM are emitted directly towards the missiles, it is considered more efficient when compared with the flare methods which emits in all directions. The experimental results of proposed method reveal that the system performs well in estimating missile signal parameters and the jamming effect is influenced by the estimated parameters.

A systematic approach for microscopic models based on cellular automata for road traffic

The transportation infrastructure is one of the most important resources for a country's economic and social well-being. The effectiveness of a country's street network will decide whether it develops further or stagnates. With the increasing number of vehicles on the road and the effects of urbanization, traffic roads are being subjected to a variety of requests and uses for which they were not designed, sized, or predicted. Because of the critical relevance of traffic roads, research must begin to lessen the effects of traffic jams in the streets, determine the appropriate number of traffic lanes, and integrate real-time traffic information into GPS systems. The goal of modeling a traffic-road system is to either build new traffic systems or gain a better knowledge of existing traffic systems so that they can be optimized. The accuracy, performance, stochastic and dynamic behavior of the model produced will be evaluated using a simulation of a genuine traffic system. This paper provides microscopic models based on cellular automation to replicate the behavior of various automobiles on a set of urban streets in Cluj Napoca city downtown. This model includes streets with multiple traffic lanes, various types of vehicles such as automobiles, buses, and trams, intersections with multiple possible upcoming streets controlled by traffic lights, bus stops inside and outside the traffic lane, tram stops inside the traffic lane, pedestrian crosswalks, and parking areas alongside and transversely with the right traffic lane of a street. TCA (Traffic Cellular Automata) is a proposed model that produces adequate findings in urban traffic theory. The results were obtained in both free-flow and traffic-jam conditions.

Analiza repetitivnog ometanja radija sa sporim frekvencijskim skakanjem

Introduction/purpose: The article presents a model of a slow frequency hopping radio in the case of repeater jamming. The aim is to analyze the effectiveness of repeater jamming to a military tactical slow frequency hopping radio. Methods: It is assumed that the repeater jammer will be successful in detecting signals with slow frequency hopping at each hop and that it will perform successful partial jamming of the intercepted communication. Under partial jamming, it is considered that a certain part of the transmission time of each hop will be jammed. A theoretical analysis of the impact of a repeater jammer on a frequency hopping radio was performed based on the definition of the total probability of error. Various parameters that affect the segment of hop duration under jamming were considered. Results: The obtained results show that high effective jamming is achieved even when a short segment of hop duration is jammed. We discuss the conditions for the repeater jammer to detect the signal during each hop and emit the jamming signal with the required strength. It has been shown that increasing the frequency hopping rate can significantly reduce the effectiveness of the repeater jammer. Conclusion: Repeater jammers are highly effective against slow frequency hopping radio communication systems.

Simulation and analysis of partial pulse remained jamming to HPRF PD radar

To solve the problem that the duty cycle of HPRF PD radar is not easy to use the general tow-and-pull jamming, a method of partial pulse remained jamming is proposed. Taking the transmitting signal of PD radar acquired by DRFM as an example, the jamming effect of the signal is simulated and analyzed. The results show that the jamming signal is modulated by the radar signal acquired by DRFM, the jamming signal generated has a strong correlation with the target Echo Signal, and it can effectively jam the HPRF PD radar with less power, which proves the effectiveness of the method.

Attacker Detection in Massive MIMO Systems Over Spatially Uncorrelated Rician Fading Channels

Physical security is a potentially promising research direction for the fifth-generation and beyond networks. This paper investigates the physical layer security of massive multiple-input multiple-output (MIMO) spatially-uncorrelated Rician fading channels in time-division duplex mode. Relying on the fact that the propagation channels need to be estimated in practice to detect the desired signals in the uplink and construct the precoding vectors in the downlink, an active attack on the pilot training phase is potentially harmful to the wireless networks.We demonstrate how a jammer can attack in the training phase of Massive MIMO with spatially-uncorrelated Rician fading channels and show the scheme for detecting the presence of a jammer. Based on the fundamental properties of Massive MIMO communication, the network can treat the jamming effects as additive white Gaussian noise. A threshold to detect the existence of the active jammer is, therefore, computed in closed-form expression with a sufficiently large number of antennas at the base station. The key merit of our proposed method is that it only requires partial channel information and two training time slots to detect the jammer activity. Numerical results manifest the effectiveness of our proposed active jamming detection over various system parameter settings. Furthermore, the benefits of the dominant line-of-sight (LoS) components have been testified. In particular, the detection probability is improved by about 1.5 times with the presence of the LoS components, while the false-alarm probability gets improved by more than ten folds.

Proactive Eavesdropping via Jamming in UAV-Enabled Suspicious Multiuser Communications

This letter studies the proactive eavesdropping with one full-duplex monitor (E) in unmanned aerial vehicle (UAV)-enabled suspicious multiuser communications, which include downlink broadcasting (DB) and uplink multiple access (UMA). Under this setup, E aims to maximize its sum eavesdropping rate by overhearing the messages from the UAV and jamming the ground multiple suspicious users simultaneously (corresponding to DB), or vice versa (corresponding to UMA). However, as the jamming power of E varies, the suspicious UAV and users will adapt their deployment and power allocation patterns concurrently to maintain the benefits of the suspicious system, which will cause certain obstacles for E to grasp its accurate jamming effect. To tackle these challenges, we first fix the jamming behavior of E and accordingly figure out the adaptiveness of the suspicious system, armed with which we further exploit the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">step characteristic</i> of the eavesdropping rate to determine the optimal (sub-optimal) jamming power of E, and the complexity involved only increases linearly with the number of suspicious users and thus avoiding the tedious exhaustive search. Simulations verify the effectiveness of the proposed schemes compared to conventional benchmarks.

Jamming Strategy Optimization through Dual Q-Learning Model against Adaptive Radar.

Modern adaptive radars can switch work modes to perform various missions and simultaneously use pulse parameter agility in each mode to improve survivability, which leads to a multiplicative increase in the decision-making complexity and declining performance of the existing jamming methods. In this paper, a two-level jamming decision-making framework is developed, based on which a dual Q-learning (DQL) model is proposed to optimize the jamming strategy and a dynamic method for jamming effectiveness evaluation is designed to update the model. Specifically, the jamming procedure is modeled as a finite Markov decision process. On this basis, the high-dimensional jamming action space is disassembled into two low-dimensional subspaces containing jamming mode and pulse parameters respectively, then two specialized Q-learning models with interaction are built to obtain the optimal solution. Moreover, the jamming effectiveness is evaluated through indicator vector distance measuring to acquire the feedback for the DQL model, where indicators are dynamically weighted to adapt to the environment. The experiments demonstrate the advantage of the proposed method in learning radar joint strategy of mode switching and parameter agility, shown as improving the average jamming-to-signal radio (JSR) by 4.05% while reducing the convergence time by 34.94% compared with the normal Q-learning method.

Numerical Integration-Based Performance Analysis of Cross-Eye Jamming Algorithm

In this paper, performance analysis of the cross-eye jamming effect under mechanical defects is dealt with. By using a numerical analysis-based approach, the performance analysis method proposed in this paper is closer to the not approximated empirical mean square difference (MSD) than the first-order Taylor approximation-based performance analysis method and the second-order Taylor approximation-based performance analysis method proposed in previous studies. In other words, the effects of amplitude ratio perturbation and phase difference perturbation on performance degradation are quantitatively analyzed. Note that the numerical integration is adopted to derive an analytic expression of the MSD.

Abating Jamming in Free Space Optical Systems—A Game-Theoretic Solution

Free space optical (FSO) channel provides a significantly large transmission capacity. However, in the presence of random jamming attacks, the efficacy of FSO communication channel can be affected critically. In this paper, the discrete-input continuous-output memoryless channel (DCMC) capacity of a single-input single-output FSO communication system is investigated under the random jamming effects. The ergodic channel capacity analysis is performed over additive non-Gaussian noise channel (jamming noise channel). The derived closed-form expression of DCMC capacity for the considered FSO system and also, the effects of partial-band jamming and broadband jamming over the FSO channel capacity are verified through simulation results. It is observed that the FSO channel capacity is very sensitive to the degree of jamming and the ergodic channel capacity alters crucially even for small change in jamming probability. The derived results are utilized to study the considered network in the presence of a rational jammer whose ability to jam is limited by its battery capacity. The presence of a rational jammer is addressed by modelling the interaction between the FSO transmitter and the jammer as a non-cooperative game. The closed-form expressions of the equilibrium of the proposed game are derived and verified through simulation. The game-theoretic solution provides a performance improvement of 74% in comparison to uniform power allocation.

Game Theory for Anti-Jamming Strategy in Multichannel Slow Fading IoT Networks

The open nature of the wireless communication medium renders it vulnerable to jamming attacks by malicious users. To detect their presence and to avoid such attacks, several techniques are present in the literature. Most of these techniques aim to reduce the effect of the jamming signals by increasing the transmission power or by using complex coordination schemes. However, the implementation of such power consuming techniques might be challenging or not feasible in limited resources Internet-of-Things (IoT) devices. Therefore, a defending strategy against jamming attacks in health monitoring IoT networks is proposed in this article. This strategy operates in orthogonal frequency-division multiplexing channels and takes into consideration the effect of slow fading channels in the strategy design. Specifically, the jamming combating problem is formulated as a Colonel Blotto game where the equilibrium defines the minimization of the worst case jamming effect on the IoT sensors communications. Then, the optimal power allocation strategy for all the potential jammer power ranges is derived by investigating the Nash equilibrium of the game. This proposed strategy is shown to be efficient in combating jamming attacks while minimizing the IoT sensors power consumption.

An anti‐jamming method in multistatic radar system based on convolutional neural network

For the existing jamming discrimination methods on the multistatic radar system, the single feature of target echo space correlation is utilised as the metric, which leads to the lack of comprehensive feature extraction and universal discrimination algorithm. In this study, a discrimination method in a multistatic radar system based on the convolutional neural network is proposed. This proposal combines the advantages of multiple-radar systems cooperative detection technology with the convolutional neural network, and effectively applies to the field of anti-deception jamming, which takes full advantage of unknown information of echo data to obtain multi-dimensional, comprehensive, complete and deep feature differences besides correlation, so as to achieve a better jamming discrimination effect. The simulation results show that the proposed method can extract the multidimensional and separable essential features of echoes, and all these features have a strong degree of differentiation between targets and jamming, which effectively reduce the influence of noise and pulse number. At the same time, the influence of radar distribution on jamming discrimination under non-ideal conditions is relieved, when the correlation coefficient of the true target reaches 0.4, the discrimination probability remains above 85%, which broadens the boundary conditions of the application process.

Generalizing hydrogel microparticles into a new class of bioinks for extrusion bioprinting.

Hydrogel microparticles (HMPs) are an emerging bioink that can allow three-dimensional (3D) printing of most soft biomaterials by improving physical support and maintaining biological functions. However, the mechanisms of HMP jamming within printing nozzles and yielding to flow remain underexplored. Here, we present an in-depth investigation via both experimental and computational methods on the HMP dissipation process during printing as a result of (i) external resistance from the printing apparatus and (ii) internal physicochemical properties of HMPs. In general, a small syringe opening, large or polydisperse size of HMPs, and less deformable HMPs induce high resistance and closer HMP packing, which improves printing fidelity and stability due to increased interparticle adhesion. However, smooth extrusion and preserving viability of encapsulated cells require low resistance during printing, which is associated with less shear stress. These findings can be used to improve printability of HMPs and facilitate their broader use in 3D bioprinting.

Optimal distributed cooperative jamming resource allocation for multi‐missile threat scenario

Jamming resources allocation (JRA) is an essential task in clustered combat environments. Especially in cases with multiple threats, efficient JRA is imperative for protecting key assets. In this study, multiple distributed outboard jammers protecting multiple targets against a multi-missile threat are considered, where the function of JRA includes jamming object selection and jammer power allocation. To address this problem, first, a scheme to evaluate the jamming effectiveness of the radar seeker under cooperative jamming from multiple jammers is proposed. Considering power allocation, a mixed-integer programing model for the optimisation of JRA is further established. A two-track simultaneous update binary particle swarm algorithm (TS-BPSO) is then devised to obtain the solutions of the JRA. Finally, the effectiveness of the proposed method for multiple jammers in the multiple missiles scenario is evaluated through simulations. The simulation results suggest that the distributed cooperative jamming resource allocation is affected by the incoming orientation of the missile and the relative position of the jammers and the targets. The findings of the study enable evaluating the use of jammer formations and provide insights into developing effective jamming strategies.

Research on Jamming to Coherent FA Radar Based on Intermittent Sampling Repeater

Due to integration of the frequency agility (FA) technology and coherent technology, Coherent FA radar has natural advantage in ECCM performance and represents one of important development trends of new radar types. Aiming at the technical characteristics of coherent FA radar, this paper proposed a jamming method to coherent FA radar based on intermittent sampling repeater. Theory models of coherent FA radar and intermittent sampling repeater jamming are established at first and the jamming effect is analyzed. The proposed jamming method is validated to be able to achieve the expected jamming effect to coherent FA radar by simulation at last.

C&I Jamming Technology Based on Frequency Diverse Array Antenna

Chopping and Interleaving (C&I) interference can produce better jamming effect on pulse compression radar. Based on this, a novel radar jamming approach to utilize frequency diverse array (FDA) antenna is proposed in this paper. Compared with the traditional phased array antennas, there is a small frequency increment (δf) between each element of the FDA antenna, which provides promising prospect to develop new radar jamming techniques. The jamming approach proposed in this paper can quickly produce more false targets. Moreover, the number of false targets is manipulated by the elements and frequency offset of FDA antenna, which indicates that many false targets can be easy to control. The simulation results provide strong support for the effect of the proposed approach.