Browsing by Subject "Jammer"

Now showing 1 - 9 of 9

Open Access
Detection of jammers in range-doppler images generated in DTED based radar simulator using convolutional neural networks
(IEEE - Institute of Electrical and Electronics Engineers, 2023-08-28) Şahinbay, H. E.; Akyol, Ali Alp; Özdemir, Ö.
Airborne radars have a variety of air-to-air and air-to-ground missions. In both air-to-air and air-to-ground target detection missions, ground clutter reflections are received from the main beam and side lobes of the radar. The effects of this clutter can be clearly seen in the radar range-Doppler maps. In addition, there may be other sources in the environment that distort the radar's range-Doppler maps. These sources can be categorized as jammer and interference signals. They distord the range-Doppler maps, making target detection more difficult, interfering with target detection and, in some cases, leading to false target detection. The detection of jammer and interference signals, which are the source of this situation, is of critical importance for the operators controlling the platform. It is often not possible for operators to quickly detect and classify these jamming signals. Deep learning methods, which have recently been used in every field, can achieve much faster and robust target detection and classification results compared to humans. In this study, the success of a Convolutional Neural Network based technique, which is one of the deep learning methods, in detecting and classifying jammer and interference signals is investigated.
Open Access
Jammer placement algorithms for wireless localization systems
(2016-07) Kurt, Mehmet Necip
The optimal jammer placement problem is proposed and analyzed for wireless localization systems. In particular, the optimal location of a jammer node is obtained by maximizing the minimum of the Cram´er-Rao lower bounds (CRLBs) for a number of target nodes under location related constraints for the jammer node. For scenarios with more than two target nodes, theoretical results are derived to specify conditions under which the jammer node is located as close to a certain target node as possible, or the optimal location of the jammer node is determined by two of the target nodes. Also, explicit expressions are provided for the optimal location of the jammer node in the presence of two target nodes. In addition, in the absence of distance constraints for the jammer node, it is proved, for scenarios with more than two target nodes, that the optimal jammer location lies on the convex hull formed by the locations of the target nodes and is determined by two or three of the target nodes, which have equalized CRLBs. Numerical examples are presented to provide illustrations of the theoretical results in different scenarios. Furthermore, an iterative algorithm is proposed for numerically determining the optimal jammer location. At each iteration of the algorithm, the jammer node is moved one step along a straight line with the purpose of increasing the CRLB(s) of the target node(s) with the minimum CRLB in the system. It is shown that the algorithm converges almost surely to the optimal jammer location under certain conditions for an infinitesimally small step size in the absence of location constraints for the jammer node. Simulations illustrate the effectiveness of the proposed algorithm in finding the optimal jammer location and its superiority in terms of the computational complexity compared to the exhaustive search over all feasible locations.
Open Access
Jamming of Wireless Localization Systems
(Institute of Electrical and Electronics Engineers Inc., 2016) Gezici, Sinan; Gholami, M. R.; Bayram, S.; Jansson M.
In this paper, the optimal jamming of wireless localization systems is investigated. Two optimal power allocation schemes are proposed for jammer nodes in the presence of total and peak power constraints. In the first scheme, power is allocated to jammer nodes in order to maximize the average Cramér-Rao lower bound (CRLB) of target nodes, whereas in the second scheme, the power allocation is performed for the aim of maximizing the minimum CRLB of target nodes. Both the schemes are formulated as linear programs, and a closed-form solution is obtained for the first scheme. For the second scheme, under certain conditions, the property of full total power utilization is specified, and a closed-form solution is obtained when the total power is lower than a specific threshold. In addition, it is shown that non-zero power is allocated to at most NT jammer nodes according to the second scheme in the absence of peak power constraints, where NT is the number of target nodes. In the presence of parameter uncertainty, robust versions of the power allocation schemes are proposed. Simulation results are presented to investigate the performance of the proposed schemes and to illustrate the theoretical results. © 2016 IEEE.
Open Access
Optimal jammer placement in wireless localization systems
(Institute of Electrical and Electronics Engineers Inc., 2016) Gezici, Sinan; Bayram, S.; Kurt, M. N.; Gholami, M. R.
In this study, the optimal jammer placement problem is proposed and analyzed for wireless localization systems. In particular, the optimal location of a jammer node is obtained by maximizing the minimum of the Cramér-Rao lower bounds (CRLBs) for a number of target nodes under location related constraints for the jammer node. For scenarios with more than two target nodes, theoretical results are derived to specify conditions under which the jammer node is located as close to a certain target node as possible, or the optimal location of the jammer node is determined by two of the target nodes. Also, explicit expressions are provided for the optimal location of the jammer node in the presence of two target nodes. In addition, in the absence of distance constraints for the jammer node, it is proved, for scenarios with more than two target nodes, that the optimal jammer location lies on the convex hull formed by the locations of the target nodes and is determined by two or three of the target nodes, which have equalized CRLBs. Numerical examples are presented to provide illustrations of the theoretical results in different scenarios. © 1991-2012 IEEE.
Open Access
Optimal jamming of wireless localization systems
(IEEE, 2015-06) Gezici, Sinan; Gholami, M.R.; Bayram, S.; Jansson, M.
In this study, optimal jamming of wireless localization systems is investigated. Two optimal power allocation schemes are proposed for jammer nodes in the presence of total and peak power constraints. In the first scheme, power is allocated to jammer nodes in order to maximize the average Cramér-Rao lower bound (CRLB) of target nodes whereas in the second scheme the power allocation is performed for the aim of maximizing the minimum CRLB of target nodes. Both schemes are formulated as linear programs, and a closed-form expression is obtained for the first scheme. Also, the full total power utilization property is specified for the second scheme. Simulation results are presented to investigate performance of the proposed schemes. © 2015 IEEE.
Open Access
Optimal power allocation for jammer nodes in wireless localization systems
(Institute of Electrical and Electronics Engineers Inc., 2017) Bayram, S.; Keskin, M. F.; Gezici, Sinan; Arıkan, Orhan
In this paper, optimal power allocation strategies are investigated for jammer nodes in a wireless localization system. Building upon the concept of the restricted Bayesian approach, a generalized optimization strategy, called the restricted scheme, is proposed for power allocation of jammer nodes, and its theoretical properties are characterized. In the restricted scheme, the aim is to maximize the average Cramér-Rao lower bound (CRLB) of target nodes while keeping their minimum CRLB above a predefined level in the presence of average (total) and peak power constraints. It is proved that the average CRLB achieved by the restricted scheme is a strictly decreasing and concave function of the constraint on the minimum CRLB level. A closed-form solution is obtained for the restricted scheme when the tradeoff parameter and the total power limit are below certain thresholds. In addition, it is shown that the optimal solution of the restricted scheme corresponds to the use of at most NT jammer nodes, where NT is the number of target nodes, and that the optimal solution of the minimum CRLB maximization scheme is determined by at most NJ target nodes, where NJ is the number of jammer nodes. Extensions of the restricted scheme and an alternative scheme that aims to maximize the number of disabled target nodes (whose CRLBs are above a preset level) are considered, and the corresponding optimal strategies for jammer power allocation are identified. Numerical examples are provided to verify the theoretical derivations for various network configurations.
Open Access
Optimum Power Allocation for Average Power Constrained Jammers in the Presense of Non-Gaussian Noise
(Institute of Electrical and Electronics Engineers, 2012-08) Bayram, S.; Vanli, N. D.; Dulek, B.; Sezer, I.; Gezici, Sinan
We study the problem of determining the optimum power allocation policy for an average power constrained jammer operating over an arbitrary additive noise channel, where the aim is to minimize the detection probability of an instantaneously and fully adaptive receiver employing the Neyman-Pearson (NP) criterion. We show that the optimum jamming performance can be achieved via power randomization between at most two different power levels. We also provide sufficient conditions for the improvability and nonimprovability of the jamming performance via power randomization in comparison to a fixed power jamming scheme. Numerical examples are presented to illustrate theoretical results.
Open Access
Power allocation strategies for channel switching and wireless localization
(2018-08) Sezer, Ahmet Dündar
Optimal power allocation is an important approach for enhancing performance of both communication and localization systems. In this dissertation, optimal channel switching problems are investigated for average capacity maximization via optimization of power resources in general. In addition, power control games are designed for a wireless localization network including anchor and jammer nodes which compete for the localization performance of target nodes. First, an optimal channel switching strategy is proposed for average capacity maximization in the presence of average and peak power constraints. Necessary and sufficient conditions are derived in order to determine when the proposed optimal channel switching strategy can or cannot outperform the optimal single channel strategy, which performs no channel switching. Also, it is obtained that the optimal channel switching strategy can be realized by channel switching between at most two different channels. In addition, a low-complexity optimization problem is derived in order to obtain the optimal channel switching strategy. Furthermore, based on some necessary conditions that need to be satisfied by the optimal channel switching solution, an alternative approach is proposed for calculating the optimal channel switching strategy. Second, the optimal channel switching problem is studied for average capacity maximization in the presence of additive white Gaussian noise channels and channel switching delays. Initially, an optimization problem is formulated for the maximization of the average channel capacity considering channel switching delays and constraints on average and peak powers. Then, an equivalent optimization problem is obtained to facilitate theoretical investigations. The optimal strategy is derived and the corresponding average capacity is specified when channel switching is performed among a given number of channels. Based on this result, it is shown that channel switching among more than two different channels is not optimal. In addition, the maximum average capacity achieved by the optimal channel switching strategy is formulated as a function of the channel switching delay parameter and the average and peak power limits. Then, scenarios under which the optimal strategy corresponds to the exclusive use of a single channel or to channel switching between two channels are described. Furthermore, sufficient conditions are obtained to determine when the optimal single channel strategy outperforms the optimal channel switching strategy. Third, the optimal channel switching problem is studied for average capacity maximization in the presence of multiple receivers in the communication system. At the beginning, the optimal channel switching problem is proposed for average capacity maximization of the communication between the transmitter and the secondary receiver while fulfilling the minimum average capacity requirement of the primary receiver and considering the average and peak power constraints. Then, an alternative equivalent optimization problem is provided and it is shown that the solution of this optimization problem satisfies the constraints with equality. Based on the alternative optimization problem, it is obtained that the optimal channel switching strategy employs at most three communication links in the presence of multiple available channels in the system. In addition, the optimal strategies are specified in terms of the number of channels employed by the transmitter to communicate with the primary and secondary receivers. Last, a game theoretic framework is proposed for wireless localization networks that operate in the presence of jammer nodes. In particular, power control games between anchor and jammer nodes are designed for a wireless localization network in which each target node estimates its position based on received signals from anchor nodes while jammer nodes aim to reduce localization performance of target nodes. Two different games are formulated for the considered wireless localization network: In the first game, the average Cram´er-Rao lower bound (CRLB) of the target nodes is considered as the performance metric, and it is shown that at least one pure strategy Nash equilibrium exists in the power control game. Also, a method is presented to identify the pure strategy Nash equilibrium, and a sufficient condition is obtained to resolve the uniqueness of the pure Nash equilibrium. In the second game, the worst-case CRLBs for the anchor and jammer nodes are considered, and it is shown that the game admits at least one pure Nash equilibrium.
Open Access
Power control games between anchor and jammer nodes in wireless localization networks
(Institute of Electrical and Electronics Engineers, 2018) Sezer, Ahmet Dündar; Gezici, Sinan
In this paper, a game theoretic framework is proposed for wireless localization networks that operate in the presence of jammer nodes. In particular, power control games between anchor and jammer nodes are designed for a wireless localization network in which each target node estimates its position based on received signals from anchor nodes while jammer nodes aim to reduce localization performance of target nodes. Two different games are formulated for the considered wireless localization network: In the first game, the average Cramér-Rao lower bound (CRLB) of the target nodes is considered as the performance metric, and it is shown that at least one pure strategy Nash equilibrium exists in the power control game. Also, a method is presented to identify the pure strategy Nash equilibrium, and a sufficient condition is obtained to resolve the uniqueness of the pure Nash equilibrium. In the second game, the worst-case CRLBs for the anchor and jammer nodes are considered, and it is shown that the game admits at least one pure Nash equilibrium. Numerical examples are presented to corroborate the theoretical results.