Application of Expectation-Maximization Algorithm to the Detection of a Direct-Sequence Signal in Pulsed Noise Jamming

We consider the detection of a direct-sequence spread-spectrum signal received in a pulsed noise jamming environment. The expectation-maximization algorithm is used to estimate the unknown jammer parameters and hence obtain a decision on the binary signal based on the estimated likelihood functions. The probability of error performance of the algorithm is simulated for a repeat code and a (7,4) block code. Simulation results show that at low signal-to-thermal noise ratio and high jammer power, the EM detector performs significantly better than the hard limiter and somewhat better than the soft limiter. Also, at low SNR, there is little degradation as compared to the maximum-likelihood detector with true jammer parameters. At high SNR, the soft limiter outperforms the EM detector

Cognitive Security Framework For Heterogeneous Sensor Network Using Swarm Intelligence

Rapid development of sensor technology has led to applications ranging from academic to military in a short time span. These tiny sensors are deployed in environments where security for data or hardware cannot be guaranteed. Due to resource constraints, traditional security schemes cannot be directly applied. Unfortunately, due to minimal or no communication security schemes, the data, link and the sensor node can be easily tampered by intruder attacks. This dissertation presents a security framework applied to a sensor network that can be managed by a cohesive sensor manager. A simple framework that can support security based on situation assessment is best suited for chaotic and harsh environments. The objective of this research is designing an evolutionary algorithm with controllable parameters to solve existing and new security threats in a heterogeneous communication network. An in-depth analysis of the different threats and the security measures applied considering the resource constrained network is explored. Any framework works best, if the correlated or orthogonal performance parameters are carefully considered based on system goals and functions. Hence, a trade-off between the different performance parameters based on weights from partially ordered sets is applied to satisfy application specific requirements and security measures. The proposed novel framework controls heterogeneous sensor network requirements,and balance the resources optimally and efficiently while communicating securely using a multi-objection function. In addition, the framework can measure the affect of single or combined denial of service attacks and also predict new attacks under both cooperative and non-cooperative sensor nodes. The cognitive intuition of the framework is evaluated under different simulated real time scenarios such as Health-care monitoring, Emergency Responder, VANET, Biometric security access system, and Battlefield monitoring. The proposed three-tiered Cognitive Security Framework is capable of performing situation assessment and performs the appropriate security measures to maintain reliability and security of the system. The first tier of the proposed framework, a crosslayer cognitive security protocol defends the communication link between nodes during denial-of-Service attacks by re-routing data through secure nodes. The cognitive nature of the protocol balances resources and security making optimal decisions to obtain reachable and reliable solutions. The versatility and robustness of the protocol is justified by the results obtained in simulating health-care and emergency responder applications under Sybil and Wormhole attacks. The protocol considers metrics from each layer of the network model to obtain an optimal and feasible resource efficient solution. In the second tier, the emergent behavior of the protocol is further extended to mine information from the nodes to defend the network against denial-of-service attack using Bayesian models. The jammer attack is considered the most vulnerable attack, and therefore simulated vehicular ad-hoc network is experimented with varied types of jammer. Classification of the jammer under various attack scenarios is formulated to predict the genuineness of the attacks on the sensor nodes using receiver operating characteristics. In addition to detecting the jammer attack, a simple technique of locating the jammer under cooperative nodes is implemented. This feature enables the network in isolating the jammer or the reputation of node is affected, thus removing the malicious node from participating in future routes. Finally, a intrusion detection system using `bait\u27 architecture is analyzed where resources is traded-off for the sake of security due to sensitivity of the application. The architecture strategically enables ant agents to detect and track the intruders threateningthe network. The proposed framework is evaluated based on accuracy and speed of intrusion detection before the network is compromised. This process of detecting the intrusion earlier helps learn future attacks, but also serves as a defense countermeasure. The simulated scenarios of this dissertation show that Cognitive Security Framework isbest suited for both homogeneous and heterogeneous sensor networks

Exploring Impacts of Random Proactive Jamming Attack in Wireless Sensor Network

Wireless Sensor networks are one of the most extensively used technologies in our day to day lives; they can provide communication without needing a fixed infrastructure, which makes them suitable for communication in disaster areas or when quick deployment is needed. However, this kinds of network technology uses the wireless medium for communication. It is vulnerable to malicious attacks. One of the most frequently used attacks is a random jamming attacks which is Denial of Service attack. Random Jamming attacks disturb the communication between Sink and legitimate nodes. In rough environments where there is constant traffic, Random jamming attack can cause serious problems. Because of this, a study of random jamming attacks and how to prevent them is necessary. In this research the random jamming attacks were simulated using Riverbed Modeler software, in order to provide a better understanding of effects of random jamming attacks. This study will be helpful for future research and development of a practical, effective way to avoid random jamming attacks. The objectives of this thesis were to simulate and analysis wireless sensor network (ZigBee) under random jamming attacks; launch different kinds of (fixed, mobile) random jamming attacks in order to test how much influence on performance of wireless sensor network. Riverbed Modeler Based simulation which have five scenarios were created and the simulation was run and the results were collected, which shows that the throughput of the wireless sensor network decrease and increase the delay ,data drop when the network is affected by the random Jammers. Finally, thesis describe the open issues in this field, such as adding more than one random jammer and sink in wireless sensor network

Wi-Fi Denial of Service Attack on Wired Analog RF Channel Emulator

This report presents the design and implementation of an analog wireless channel emulator to examine various denial of service attacks in multiple mobile scenarios. The scenarios emulated in this project involve three node topologies of wireless interferers (Wi-Fi radios), including a software defined radio that transmits one of three denial of service (DoS) waveforms. The testbed was functional and met the original specifications. Results from mobile experiments show a clear distinction in performance among the three DoS waveforms depending on the node topology; a digital waveform using binary phase shift keying (BPSK) is most effective at reducing total network throughput at close range while sweep waveforms exhibit minor throughput reduction from a greater distance

GNSS Radio Frequency Interference Monitoring from LEO Satellites: An In-Laboratory Prototype

The disruptive effect of radio frequency interference (RFI) on global navigation satellite system (GNSS) signals is well known, and in the last four decades, many have been investigated as countermeasures. Recently, low-Earth orbit (LEO) satellites have been looked at as a good opportunity for GNSS RFI monitoring, and the last five years have seen the proliferation of many commercial and academic initiatives. In this context, this paper proposes a new spaceborne system to detect, classify, and localize terrestrial GNSS RFI signals, particularly jamming and spoofing, for civil use. This paper presents the implementation of the RFI detection software module to be hosted on a nanosatellite. The whole development work is described, including the selection of both the target platform and the algorithms, the implementation, the detection performance evaluation, and the computational load analysis. Two are the implemented RFI detectors: the chi-square goodness-of-fit (GoF) algorithm for non-GNSS-like interference, e.g., chirp jamming, and the snapshot acquisition for GNSS-like interference, e.g., spoofing. Preliminary testing results in the presence of jamming and spoofing signals reveal promising detection capability in terms of sensitivity and highlight room to optimize the computational load, particularly for the snapshot-acquisition-based RFI detector

Impact Study of Unintentional Interference on GNSS Receivers

This work has been performed in the context of an Administrative Arrangement for DG HOME. The overall scope is to perform an impact assessment of radio frequency (RF) interference on critical infrastructures relying on GNSS-services for timing and synchronization purposes. In WP3, the analysis has been divided into the impact of intentional interference on critical infrastructures presented in WP3.1 and the analysis of unintentional interference, covered in this report. DVB-T has been identied as the most important source of unintentional interference in the GNSS frequency bands and therefore a special attention is paid to this interference source. The main motivation to assess the performance reduction of receivers due to unintentional interference, is related to the high probability of these events. Unintentional interference stems from out-of-band emissions or spurious transmissions. Four different scenarios have been considered in this work, covering (i) additive white Gaussian noise, (ii) continuous wave interference, (iii) pulsed continuous wave nterference and (iv) interference that stems from the third harmonic of DVB-T transmissions. All these scenarios are highly relevant and are frequently observed in realistic signal conditions. The scenario of DVB-T interference receives most of the attention in this work, since DVB-T has become the most widely adopted digital terrestrial television broadcasting standard in the world. Harmonics of the DVB-T signal could possibly fall together with the GPS L1 or Galileo E1 bands and as such become a threat. DVB-T services are operational in more than 40 countries, with more than 75% of the deployment in Europe. In the coming years, DVB-T is expected to be deployed in more than 100 countries. In the frame of this work, different tools have been developed to quantify the impact of unintentional interference. First, a laboratory testbed has been set up, that allows to take real GPS L1 signals, combine them with synthetic interfering signals and test the robustness of different commercial and professional receivers. Further, in order to have a full control of the signal characteristics and the implementation details of the receiver, a simulation platform has been developed. This simulation tool generates GNSS as well as interfering signals, and observes consequently the impact on the acquisition or tracking performance for different receiver implementations. Finally, since it is difcult to reach statistical signicance for the acquisition performance, an analytical tool has been developed allowing to evaluate the effects of interference. This report summarises the relevant results for the four considered scenarios. For the assessment of the acquisition performance the analytical tool and the simulation platform have been used. In order to evaluate the tracking performance, experimental work has been conducted with real receivers and simulations have been performed. For the acquisition, the report quanties how much the probability of detection and the probability of false alarm are affected by the presence of interference. For the tracking, the main result of this report is the quantication of the signal degradation in terms of C=N0 and in terms of the variance of the position solution. In the scenario of DVB-T Page 2 of 94 WP3.2 interference, the degradation of the signal quality has been determined as a function of the DVB-T third harmonic power and the distance between the victim receiver and the DVB-T base station.JRC.DG.G.6-Security technology assessmen

Performance of IEEE 802.11a wireless LAN standard over frequency-selective, slowly fading Nakagami channels in a pulsed jamming environment

Wireless local area networks (WLAN) are increasingly important in meeting the needs of the next generation broadband wireless communication systems for both commercial and military applications. In 1999, the Institute of the Electrical and Electronics Engineers (IEEE) 802.11a working group approved a standard for a 5 GHz band WLAN that supports a variable bit rate from 6 to 54 Mbps, and orthogonal frequency-division multiplexing (OFDM) was chosen because of its well-known ability to avoid multipath effects while achieving high data rates by combining a high order sub-carrier modulation with a high rate convolutional code. This thesis investigates the performance of the OFDM based IEEE.802.11a WLAN standard in frequency-selective, slowly fading Nakagami channels in a pulsed-noise jamming environment. Contrary to expectations, the signal-to-interference ratio (SIR) required to achieve a specific does not monotonically decrease when the bit rate decreases. Furthermore, the results show that the performance is improved significantly by adding convolutional coding with Viterbi decoding, and thus highlights the importance of forward error correction (FEC) coding to the performance of wireless communications systems.http://archive.org/details/performanceofiee109453638Lieutenant Junior Grade, Turkish NavyApproved for public release; distribution is unlimited

Randomized Differential DSSS: Jamming-Resistant Wireless Broadcast Communication

Abstract—Jamming resistance is crucial for applications where reliable wireless communication is required. Spread spectrum techniques such as Frequency Hopping Spread Spectrum (FHSS) and Direct Sequence Spread Spectrum (DSSS) have been used as countermeasures against jamming attacks. Traditional antijamming techniques require that senders and receivers share a secret key in order to communicate with each other. However, such a requirement prevents these techniques from being effective for anti-jamming broadcast communication, where a jammer may learn the shared key from a compromised or malicious receiver and disrupt the reception at normal receivers. In this paper, we propose a Randomized Differential DSSS (RD-DSSS) scheme to achieve anti-jamming broadcast communication without shared keys. RD-DSSS encodes each bit of data using the correlation of unpredictable spreading codes. Specifically, bit “0 ” is encoded using two different spreading codes, which have low correlation with each other, while bit “1 ” is encoded using two identical spreading codes, which have high correlation. To defeat reactive jamming attacks, RD-DSSS uses multiple spreading code sequences to spread each message and rearranges the spread output before transmitting it. Our theoretical analysis and simulation results show that RD-DSSS can effectively defeat jamming attacks for anti-jamming broadcast communication without shared keys. I