Papers by Zlatka Valkova-Jarvis
Quantum Technology: Unleashing the Power and Shaping the Future of Cybersecurity
2023 Eight Junior Conference on Lighting (Lighting)
Statistical Evaluation of Classification Models for PCA Detection
Performance Comparison and Analysis of AODV, DSDV and DSR Routing Protocols in VANET for Urban Scenario
2023 Eight Junior Conference on Lighting (Lighting)
Security Threats and Models in the Field of Renewable Energy Systems
2023 Eight Junior Conference on Lighting (Lighting)
Symmetry, Dec 20, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
An overview of methods to combat eavesdropping in NOMA-based networks through physical layer security
IOP Conference Series: Materials Science and Engineering, 2021
Thanks to their potentials in providing reliable communications for a large number of devices, 5G... more Thanks to their potentials in providing reliable communications for a large number of devices, 5G non-orthogonal multiple access (NOMA) techniques have recently been the subject of considerable research interest. Accordingly, research of Physical Layer Security approaches in NOMA is essential. A primary purpose and challenge for security at the physical level of NOMA-based systems is to protect the information transmitted against both external and internal eavesdropping attacks. To this end, it is necessary to develop PLS schemes which allow each user to decode the signals transmitted by other users, thus guaranteeing normal operation of the successive interference cancellation, while also providing privacy of the information exchange. In this paper, different types of eavesdropping are studied and a summary of existing approaches to improve security at the physical layer in 5G NOMA networks is provided.
Reliable and Secure LPWAN Communication in Interference Environments
River Publishers eBooks, 2019
THE 9TH INTERNATIONAL CONFERENCE OF THE INDONESIAN CHEMICAL SOCIETY ICICS 2021: Toward a Meaningful Society
The close relationship between multiple access technologies and efficient spectrum utilization ma... more The close relationship between multiple access technologies and efficient spectrum utilization makes powerdomain non-orthogonal multiple access (NOMA) an attractive solution that enables the support of high data rates, user fairness and low-latency communications in 5G and next generation networks. However, user pairing and successive interference cancelation applied in NOMA facilitates eavesdropping on the far user's signal by the near user establishing security as a main issue in NOMA systems. Due to their numerous advantages, the means of physical layer security (PLS) are extremely suitable to combat internal NOMA eavesdropping. Up to the present only a few studies exist which examine different PLS approaches against eavesdropping on the far user by the near user. Among them are a joint beamforming and power allocation algorithm, an angle conversion method that alters the original signal constellation before transmission, and a directional modulation approach. In this paper, the available PLS methods against eavesdropping on the far user by the near user are investigated and the main advantages and drawbacks of these methods are compared.
Symmetry
In this paper, a new method for designing orthogonal bicomplex digital signal processing (DSP) al... more In this paper, a new method for designing orthogonal bicomplex digital signal processing (DSP) algorithms is developed. In contrast to those previously reported on, the method proposed is universal, since it is not affected by the order or the type of the real digital processing algorithm employed as a prototype. The method is based on a transformation starting with either real or complex orthogonal DSP algorithms represented in the z-domain, and transforming them into orthogonal bicomplex algorithms. The proposed new method is applied in the design of bilinear orthogonal bicomplex DSP systems with a canonical number of elements, the main advantage of which is that the order of the digital system is reduced by a factor of four. As well as being canonical, the orthogonal bicomplex digital systems are also symmetrical structures, as a result of which they offer parallelism and subsequent unification. It is experimentally shown that bicomplex orthogonal DSP algorithms acquire the prope...
One possible approach for maintaining the security of communication systems relies on Physical La... more One possible approach for maintaining the security of communication systems relies on Physical Layer Security mechanisms. However, in wireless time division duplex systems, where uplink and downlink channels are reciprocal, the channel estimate procedure is exposed to attacks known as pilot contamination, with the aim of having an enhanced data signal sent to the malicious user. The <em>Shifted</em> <em>2-N-PSK</em> method involves two random legitimate pilots in the training phase, each of which belongs to a constellation, shifted from the original N-PSK symbols by certain degrees. In this paper, legitimate pilots' offset values and their influence on the detection capabilities of the <em>Shifted</em> <em>2-N-PSK</em> method are investigated. As the implementation of the technique depends on the relation between the shift angles rather than their specific values, the optimal interconnection between the two legitimate constellation...
African Journal of Information & Communication Technology
Signal distortions in communication systems occur between the transmitter and the receiver; these... more Signal distortions in communication systems occur between the transmitter and the receiver; these distortions normally cause bit errors at the receiver. In addition interference by other signals may add to the deterioration in performance of the communication link. In order to achieve reliable communication, the effects of the communication channel distortion and interfering signals must be reduced using different techniques. The aim of this paper is to introduce the fundamentals of Orthogonal Frequency Division Multiplexing (OFDM) and Orthogonal Frequency Division Multiple Access (OFDMA), to review and examine the effects of interference in a digital data communication link and to explore methods for mitigating or compensating for these effects.
Applications of Digital Signal Processing, 2011
Signal, Image and Video Processing, 2009
In this article, very low sensitivity variable complex filter (VCF) sections are developed. They ... more In this article, very low sensitivity variable complex filter (VCF) sections are developed. They have two important advantages: extremely low passband sensitivity and independent tuning of the bandwidth and the central frequency over a wide frequency range. The first advantage provides resistance to quantization effects, while the second one gives a better digital signal processing quality and extends the area of possible applications of the developed filters. Based on the proposed VCF sections an adaptive complex system is designed which demonstrates very fast convergence and low computational complexity. This system is applied for narrowband interference cancellation in multiband orthogonal frequency division multiplexing receivers and wideband noise cancellation in OFDM receivers. It is experimentally verified that a better signal-to-noise ratio and signal-to-interference ratio can be achieved using the proposed adaptive complex filtering scheme.
MATEC Web of Conferences, 2017
One of the problems phasing the physical layer security of a wireless system is its vulnerability... more One of the problems phasing the physical layer security of a wireless system is its vulnerability to pilot contamination attacks and hence schemes for its detection need to be applied. A method proposed in the literature consists of training with two N-PSK pilots. Although the method is effective in most of the cases, it is not able to discover an attack initiated during the transmission of the second pilot from the pair if both the legitimate and non-legitimate pilots coincide. In this current paper, an improvement to this method is proposed which detects an intruder who misses the first pilot transmission. The suggested improvement eliminates the usage of threshold values in the detection-a main drawback of previously existing solution.
Design and Realization of Efficient IIR Digital Filter Structures Based on Sensitivity Minimizations
All in-text references underlined in blue are linked to publications on ResearchGate, letting you... more All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately.
Performance Evaluation of Constellation Diagram Analysis-based Methods for PCA Detection
2021 29th National Conference with International Participation (TELECOM)
WSEAS TRANSACTIONS on COMMUNICATIONS archive, 2017
Wireless communication systems are very vulnerable to pilot contamination attacks, which represen... more Wireless communication systems are very vulnerable to pilot contamination attacks, which represents a major physical layer security issue. Hence, it is necessary to apply different approaches and methods to the detection of this type of attack. One effective method proposed in the literature is 2-N-PSK pilot detection, which consists of training with two random N-PSK pilots. Although the method is broadly effective, it is not able to detect an attack initiated during the transmission of the second pilot of the pair in the case when both the legitimate and non-legitimate pilots coincide. In this paper, an improvement to this method is proposed to detect an intrusion which misses the first pilot transmission and initiates an attack during the second training period. This improved technique is based on channel gain comparison and eliminates the need to use threshold values in the detection – a drawback of previously-existing solutions.
Very Low Sensitivity Complex Coefficients Band-Pass Filter Sections
After development and proper selection and investigation of different prototype low-pass sections... more After development and proper selection and investigation of different prototype low-pass sections, very low magnitude sensitivity first- and second-order complex coefficient orthogonal digital filter structures are derived. Then, a comparative study together with other known structures is conducted and it is shown that, by having canonic (minimum) number of multipliers and delay elements, the new structures employ more than two times (for first-order) and more than three times (for second-order) less elements, ensuring in the same time tens or hundreds of times lower sensitivity for narrow-band realizations. It is demonstrated experimentally that the new structures are preserving their magnitude responses even when the coefficient word-length is reduced to 2 bits of canonic SD-code, while the response of the other known structures are totally destroyed even with 3 bits word-length. The new structures are suitable for realization of high quality narrow-band orthogonal filters of high...
Detecting Pilot Contamination Attacks in Wireless Cyber-Physical Systems
Cybersecurity and Privacy in Cyber-Physical Systems, 2019
Performance Comparison of FBMC Prototype Filters with Flexible Numerology for 5G V2I Wireless Networks
2019 14th International Conference on Advanced Technologies, Systems and Services in Telecommunications (TELSIKS), 2019
In 5th generation (5G) wireless networks high levels of spectral and energy efficiency, reliabili... more In 5th generation (5G) wireless networks high levels of spectral and energy efficiency, reliability and connectivity have to be maintained. Moreover, the ever-increasing requirements for high data rates and low latency, especially when ultra-reliable communications are envisaged, lead to the need for profound examination of wireless technologies and how to improve them. Additionally, from the physical layer perspective, the various types of modulation recently proposed for 5G networks will have the ability to offer well-controlled low levels of interference and reduced Out-of-Band (OOB) leakage, thus maintaining high spectral efficiency. In this paper, the pulse shaping approach implemented through prototype filters with flexible numerology in Filter Bank Multicarrier (FBMC) is studied in Vehicle-to-Infrastructure (V2I) communications characterized by high delay spreads and high velocities of the User Equipment (UE). The key benefits of FBMC technology over Orthogonal Frequency Divi...
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Papers by Zlatka Valkova-Jarvis