Channel Jamming Research Articles

부분 대역 재밍 채널에서 연접 극 부호의 설계 및 복호 기법

본 논문은 부분 대역 재밍(partial-band jamming, PBJ) 채널에 주파수 도약 대역 확산(frequency-hopping spread-spectrum, FHSS) 시스템을 사용할 때 적용 가능한 연접 극 부호의 설계 및 복호 기법을 제안한다. 제안하는 연접 부호의 외부 부호로는 RS(Reed-Solomon) 부호와 극 부호를 고려하였고, 내부 부호는 극 부호로 하나의 내부 부호가 한 홉에 대응되도록 설계하였다. 유한한 길이에서 동작하는 극 부호는 순환중복검사(cyclic redundancy check, CRC) 비트와 연접하여 복호 성능을 향상시킬 수 있고, 복호 결과가 CRC를 만족하는지 여부를 활용하여 복호 실패 여부를 판정할 수 있다. 내부 부호의 CRC 조력 리스트 연속 제거 복호(CRC aided successive cancellation list decoding, CA-SCL decoding) 과정에서 계산된 경로 메트릭을 활용하면, 복호에 실패한 경우를 추가로 판정 가능하며 이를 소실(erasure)로 처리하여 외부 부호 복호 과정에서 이득을 얻어 연접 부호의 성능이 향상된다. 소실 삽입 기법과 더불어서 내부 부호의 복호 결과를 클리핑(clipping)하여, 재밍의 세기가 강할 때 추가적인 복호 성능 향상을 확인하였다. 마지막으로, 연접 부호의 외부 부호로 RS 부호보다 극 부호를 사용하면 연판정 이득으로 인한 성능 향상을 얻을 수 있음을 확인하였다.

Secret Channel Training to Enhance Physical Layer Security With a Full-Duplex Receiver

This paper proposes a new channel training (CT) scheme for a full-duplex receiver to enhance physical layer security. Equipped with $N_{B}$ full-duplex antennas, the receiver simultaneously receives the information signal and transmits artificial noise (AN). In order to reduce the non-cancellable self-interference due to the transmitted AN, the receiver has to estimate the self-interference channel prior to the data communication phase. In the proposed CT scheme, the receiver transmits a limited number of pilot symbols that are known only to itself. Such a secret CT scheme prevents an eavesdropper from estimating the jamming channel from the receiver to the eavesdropper, hence effectively degrading the eavesdropping capability. We analytically examine the connection probability (i.e., the probability of the data being successfully decoded by the receiver) of the legitimate channel and the secrecy outage probability due to eavesdropping for the proposed secret CT scheme. Based on our analysis, the optimal power allocation between CT and data/AN transmission at the legitimate transmitter/receiver is determined. Our examination shows that the newly proposed secret CT scheme significantly outperforms the non-secret CT scheme that uses publicly known pilots when the number of antennas at the eavesdropper is larger than one.

Cooperative Antijamming Relaying for Control Channel Jamming in Vehicular Networks

Radio Frequency jamming attacks constitute a major threat to the availability of the vehicular networks. In particular, if the control channel is under persistent jamming attacks, the victim vehicles may fail to receive the safety related messages from the Road Side Unit, which can possibly cause tremendous economic loss and claim human lives. In this paper, we propose a cooperative relaying scheme to circumvent the control channel jamming problem in the vehicular networks, whereby the vehicles outside of the jamming area serve as relays to help forward the received control channel signal to the victim vehicles through another jamming-free service channel. By combining the signals from all relays using the selection combining or maximum-ratio combining methods, the spatial diversity provided by the relays can be effectively exploited to reduce the outage probability of the victim vehicles. Theoretical models are developed to characterize the performance of this cooperative antijamming relaying scheme, which take into account both the large-scale path loss and small-scale channel fading between relaying and victim vehicles under different jamming scenarios. We also propose a relay selection scheme to optimize the performance of the victim vehicles under the relay number constraint. Simulation results are provided to show the performance of the proposed cooperative relaying scheme and relay selection algorithm under different network settings.

Optimal jamming attack schedule for remote state estimation with two sensors

In cyber-physical systems (CPS), cyber threats emerge in many ways which can cause significant destruction to the system operation. In wireless CPS, adversaries can block the communications of useful information by channel jamming, incurring the so-called denial of service (DoS) attacks. In this paper, we investigate the problem of optimal jamming attack scheduling against remote state estimation wireless network. Specifically, we consider that two wireless sensors report data to a remote estimator through two wireless communication channels lying in two unoverlapping frequency bands, respectively. Meanwhile, an adversary can select one and only one channel at a time to execute jamming attack. We prove that the optimal attack schedule is continuously launching attack on one channel determined based on the system dynamics matrix. The theoretical results are validated by numerical simulations.

Robust Relay Beamforming Against Jamming Attack

In this letter, we surpass the jamming effect and also estimate the jamming channel state information by using the Kalman filtering approach. Furthermore, we design a closed-form beamforming weight for maximizing the achievable rate subject to the condition that the total relays power transmission would be below a predefined threshold level, which is formulated as a quadratically constrained quadratic program. Simulation results show the efficient performance of the proposed method for different destruction powers of the jammer by achieving the Cramer–Rao lower bound.

Jamming-Resistant Receivers for the Massive MIMO Uplink

We design a jamming-resistant receiver scheme to enhance the robustness of a massive MIMO uplink system against jamming. We assume that a jammer attacks the system both in the pilot and data transmission phases. The key feature of the proposed scheme is that, in the pilot phase, we estimate not only the legitimate channel, but also the jamming channel by exploiting a purposely unused pilot sequence. The jamming channel estimate is used to constructed linear receive filters that reject the impact of the jamming signal. The performance of the proposed scheme is analytically evaluated using asymptotic properties of massive MIMO. The optimal regularized zero-forcing receiver and the optimal power allocation are also studied. Numerical results are provided to verify our analysis and show that the proposed scheme greatly improves the achievable rates, as compared to conventional receivers. Interestingly, the proposed scheme works particularly well under strong jamming attacks, since the improved estimate of the jamming channel outweighs the extra jamming power.

Enabling Self-Healing Smart Grid Through Jamming Resilient Local Controller Switching

A key component of a smart grid is its ability to collect useful information from a power grid for enabling control centers to estimate the current states of the power grid. Such information can be delivered to the control centers via wireless or wired networks. It is envisioned that wireless technology will be widely used for local-area communication subsystems in the smart grid (e.g., in distribution networks). However, various attacks with serious impact can be launched in wireless networks such as channel jamming attacks and denial-of-service attacks. In particular, jamming attacks can cause significant damages to power grids, e.g., delayed delivery of time-critical messages can prevent control centers from properly controlling the outputs of generators to match load demands. In this paper, a communication subsystem with enhanced self-healing capability in the presence of jamming is designed via intelligent local controller switching while integrating a retransmission mechanism. The proposed framework allows sufficient readings from smart meters to be continuously collected by various local controllers to estimate the states of a power grid under various attack scenarios. The jamming probability is also analyzed considering the impact of jammer power and shadowing effects. In addition, guidelines on optimal placement of local controllers to ensure effective switching of smart meters under jamming are provided. Via theoretical, experimental and simulation studies, it is demonstrated that our proposed system is effective in maintaining communications between smart meters and local controllers even when multiple jammers are present in the network.

Disrupting Anti-Jamming Interference Alignment Sensor Networks with Optimal Signal Design

Anti-jamming interference alignment (IA) can battle with the adversarial jamming signals for IA sensor networks effectively. In this letter, we design jamming signals to optimally disrupt the transmission of anti-jamming IA sensor networks. Specifically, with only the jamming channel information known for the jammer, we design the jamming signal to minimize the signal-to-jamming-plus-noise ratio (SJNR) at a certain targeted IA receiver with the jamming power constraints. Furthermore, an approximate expression of the minimized SJNR is presented to estimate the jamming performance theoretically. Simulation results are provided to verify the effectiveness of the proposed optimal jamming scheme towards IA sensor networks.

Transmission Strategy Against Opportunistic Attack for MISO Secure Channels

For a multiple-input-single-output secure channel, we consider the transmission strategies, including transmission rate and beamformer against opportunistic attack, which eavesdrops or generates jamming signal with certain probabilities. Based on the perfect and partial channel state information of jamming channel, we design the transmission strategies against the jamming, eavesdropping, and both attacks. Then, we provide the optimal transmission strategy in terms of expected secrecy rate for the given attack strategy.

부분 대역 재밍 채널에서 LDPC 부호화된 주파수 도약 BFSK 시스템의 소실 삽입 및 클리핑 기법

In this paper, we propose a clipping method for LDPC coded FH BFSK system over partial-band jamming channel. We apply the erasure insertion technique, which had been studied much earlier, now to LDPC codes and discuss its performance degradation region. By using clipping technique, the performance degradation can be removed. Finally, we discuss the erasure insertion and clipping techniques for various jamming conditions.

Modeling of Channel Jamming in Dynamic Spectrum Access Networks

Dynamic Spectrum Access (DSA) network is envisioned as a promising candidate to significantly improve the spectrum utilization. Due to its specific features of the DSA, however, this network is more vulnerable to security attacks than the traditional wireless networks. And channel jamming is a one of main threats to DSA networks. So far, limited works have been done in mathematical and formal modeling of the channel jamming. In this paper, we present the at- tempts to analyze the channel jamming behaviors in DSA networks in order to find a relationship between the number of channels, secondary users and attackers. The research focuses on jamming performance analysis in various architectures, that is, a simple DSA network and a complex DSA network with varied situations. Comparisons between theoretical and simulation results in Matlab verify that the modeling and analysis are valid.

Worst-Case Jamming on MIMO Gaussian Channels

Worst-case jamming of legitimate communications over multiple-input multiple-output Gaussian channels is studied in this paper. A worst-case scenario with a `smart' jammer that knows all channels and the transmitter's strategy and is only power limited is considered. It is shown that the simplification of the system model by neglecting the properties of the jamming channel leads to a loss of important insights regarding the effects of the jamming power and jamming channel on optimal jamming strategies of the jammer. Without neglecting the jamming channel, a lower-bound on the rate of legitimate communication subject to jamming is derived, and conditions for this bound to be positive are given. The lower-bound rate can be achieved regardless of the quality of the jamming channel, the power limit of the jammer, and the transmit strategy of the jammer. Moreover, general forms of an optimal jamming strategy, on the basis of which insights into the effect of jamming power and jamming channel are exposed, are given. It is shown that the general forms can lead to closed-form optimal jamming solutions when the power limit of the jammer is larger than a threshold. Subsequently, the scenario in which the effect of jamming dominates the effect of noise (the case of practical interest) is considered, and an optimal jamming strategy is derived in closed-form. Simulation examples demonstrate lower-bound rates, performance of the derived jamming strategy, and an effect of inaccurate channel information on the jamming strategy.

On singularity attacks in MIMO channels

AbstractAll multiple‐input multiple‐output (MIMO) systems need a method to estimate and equalise their channel, whether through channel reciprocity or sounding, and most modern orthogonal frequency division multiplexing (OFDM)‐based MIMO waveforms use sounding via OFDM pilot tones. Previous research has focused on jamming data transmissions. We instead focus on jamming channel sounding symbols and introduce the MIMO singularity attack, which attempts to reduce the rank of the channel gain matrix estimate by the receiver through transmission of specific jamming signals. More specifically, we introduce and analyse the MIMO singularity attack, in which a multi‐antenna jammer tries to manipulate pilot tones to skew the channel state information obtained at the receiver. We prove singularity jamming can be more destructive than data jamming attacks such as barrage or pilot jamming by studying its effects on channel bit error rate and capacity. We develop the constraints associated with jamming MIMO sounding channels and further describe how these attacks specifically impact data symbol estimates for OFDM pilot‐based sounding systems. Through simulation, we demonstrate efficiency gains over barrage jamming. Copyright © 2013 John Wiley & Sons, Ltd.

Hybrid Carrier CDMA Communication System Based on Weighted-Type Fractional Fourier Transform

Recently, an approach based on carrier scheme convergence was proposed based on the weighted-type fractional Fourier transform (WFRFT). Meanwhile, in the high-speed wireless communication systems, code division multiple access (CDMA) is an efficient technique for interference in the frequency-selective fading channels. In this letter, we combine the hybrid carrier (HC) scheme with CDMA and frequency domain linear equalization. The proposed system can not only provide the compatibility with single carrier (SC) CDMA and multi-carrier (MC) CDMA systems, but also achieve a smooth and seamless transition between the two. The proposed system can switch to single carrier or multi-carrier scheme under the specific conditions. Moreover, HC-CDMA outperforms SC-CDMA and MC-CDMA systems over the frequency-selective fading channel and single frequency jamming channel.

Partial band jamming of multicarrier frequency hopping/binary phase shift keying receiver over a Rayleigh fading channel with imperfect channel estimation

The combined effect of partial band jamming and imperfect channel estimation on the analysis of the performance of MC-FH/BFSK receiver over a Rayleigh fading channel is often neglected in the literature. In this study, this missing analysis is provided. The authors derive closed form bit error probability (BEP) expressions for studying the effect of partial band and broad-band jamming on the performance of a coherent uncoded MC-FH/BFSK receiver over a Rayleigh fading channel where the effect of channel estimation errors is not neglected. The considered model of the channel estimation errors does not assume independency between amplitude and phase estimates. Computer simulations are provided to validate the theoretical developments. It is shown that the smart partial band jammer should be present in all sub-bands of the system in order to be effective.

Error probability analysis of multicarrier direct sequence code division multiple access system under imperfect channel estimation and jamming in a Rayleigh fading channel

The performance of a multicarrier direct sequence code division multiple access (MC-DS-CDMA) system in fading environment has been extensively analysed in the literatures. The analysis that is available in the literatures did not take into account the impact of jamming and channel estimation errors on the performance of the system. In this study, closed-form expressions of the average bit error probability (BEP) of the MC-DS-CDMA system with channel estimation errors in the presence of partial band, broadband and multitone jamming are derived in a Rayleigh fading channel. The analysis shows that the magnitude of the normalised correlation between the actual and the estimated complex fading channel gain, A, greatly affects the performance of the MC-DS-CDMA system. For large signal-to-noise ratio, the average BEP with A=1 and without multiple access interference (MAI) tends to zero. When A≠1, the BEP of the system exhibits an error floor even without MAI. This error floor increases as the number of users increases. It is also shown that increasing the number of the system subcarriers enhances the system performance against jamming.

Mitigation of Control Channel Jamming under Node Capture Attacks

Availability of service in many wireless networks depends on the ability for network users to establish and maintain communication channels using control messages from base stations and other users. An adversary with knowledge of the underlying communication protocol can mount an efficient denial of service attack by jamming the communication channels used to exchange control messages. The use of spread spectrum techniques can deter an external adversary from such control channel jamming attacks. However, malicious colluding insiders or an adversary who captures or compromises system users is not deterred by spread spectrum, as they know the required spreading sequences. For the case of internal adversaries, we propose a framework for control channel access schemes using the random assignment of cryptographic keys to hide the location of control channels. We propose and evaluate metrics to quantify the probabilistic availability of service under control channel jamming by malicious or compromised users and show that the availability of service degrades gracefully as the number of colluding insiders or compromised users increases. We propose an algorithm called GUIDE for the identification of compromised users in the system based on the set of control channels that are jammed. We evaluate the estimation error using the GUIDE algorithm in terms of the false alarm and miss rates in the identification problem. We discuss various design trade-offs between robustness to control channel jamming and resource expenditure.

On antijamming in general CDMA systems-part I: multiuser capacity analysis

The capacity of a general multiuser CDMA jamming channel is analyzed when the receiver has or lacks jammer state information. Analyses are carried out for noncooperative and cooperative users in uplink and downlink static and Nakagami fading channels. The results are applied to a versatile multiaccess channel model which is based on the time-bandwidth dimensionality and is considered for the user capacity analysis of a variety of multiuser spread spectrum systems contaminated by jamming. In this model, different users are distinguished by signatures of either direct sequence or hopping type. It is found that the jammer should spread its energy evenly over all degrees of freedom in order to minimize the average capacity. Also, the capacity behavior appears to be dominated more by knowledge of jammer state information than by the effects of fading. The capacity of downlink channels in cooperative schemes is found to be more sensitive to changes in fading severity, compared with the capacity of other kinds of channels.

On Antijamming in General CDMA Systems-Part II: Antijamming Performance of Coded Multicarrier Frequency-Hopping Spread Spectrum Systems

In the first part of the paper, the capacity of a general multiuser code division multiple access (CDMA) jamming channel was analyzed for noncooperative and cooperative users in uplink and downlink static and Nakagami fading channels when the receiver has or lacks jammer state information. The results were applied to a unified channel model encompassing a variety of multiuser spread spectrum systems contaminated by jamming. It was found that the jammer should spread its energy evenly over all degrees of freedom in order to minimize the average capacity. In the second part of the paper, using a standard orthogonal frequency division multiplexing (OFDM) model, the performance of a coded version of a multicarrier frequency-hopping (MC-FH) CDMA system in static and Rayleigh fading jamming uplink channels is analyzed. The MC-FH system under study is a hybrid of the OFDM and frequency hopping concepts, and is also a practical example of the model developed in the first part. It is demonstrated that in the cases where the receiver knows the jammer state and the receiver lacks the jammer state, spreading and contracting the jamming power over the system bandwidth, respectively, will give rise to the worst performance for the communicators. Optimal decorrelator weights for the receiver soft outputs in different channels, valuable for practical system design, are also obtained.

Wormhole-Based Antijamming Techniques in Sensor Networks

Due to their very nature, wireless sensor networks are probably the category of wireless networks most vulnerable to radio channel jamming”-based Denial-of-Service (DoS) attacks. An adversary can ...