Krasen Angelov

Dr. Krasen Angelov

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Academic Career Length

10Years (2017-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 January 2021 in IOP Conference Series: Materials Science and Engineering
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Conference Paper
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KAKrasen Angelov
Krasen Angelov
SSStanimir Mihaylov Sadinov
Stanimir Mihaylov Sadinov
PKPANAGIOTIS KOGIAS
PANAGIOTIS KOGIAS
The need for digital transformation in the industry and the related development of the Internet of Things (IoT) has led to the rapid development of various communication technologies and approaches for the implementation of flexible and intelligent communication networks. The main direction is wireless technologies, which make it possible to accelerate the wide range of new applications and services related to smart cities, industry, e-government and others. The possibilities are wide - use of different licensed or unlicensed frequency bands, channel bandwidths, modulation formats, power efficiency, reliability and security. Different network topologies could be applied for the access and collection of data from the sensor networks - star topology, mesh topology, tree topology, each of which has different advantages and disadvantages. This paper discusses the possibilities for deploying low-power mesh networks in an indoor scenario based on IQRF technology. Important communication parameters, approach advantages, and technological limitations will be highlighted. As an example, a study of network behaviour and efficiency in an indoor scenario will be considered.
17 April 2025 in Journal of Imaging
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Journal Article
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Hristina StoychevaHristina Stoycheva
Hristina Stoycheva
GMGeorgi Mihalev
Georgi Mihalev
SSStanimir Mihaylov Sadinov
Stanimir Mihaylov Sadinov
KAKrasen Angelov
Krasen Angelov
This paper presents a modified image encryption scheme based on the OTP (One-Time Pad) algorithm, consisting of chaotic synchronization and artificial neural networks (ANNs) for improved security and efficiency. The scheme uses chaotic synchronization based on feedback control to create complex and unique encryption keys. Additionally, ANNs are used to approximate time functions, creating a neural encoding key, which adds an additional layer of complexity to the encryption process. The proposed scheme integrates static, chaotic, and neural keys in a multilayer structure, providing high resistance against statistical and cryptographic attacks. The results show that the proposed methodology achieves entropy values close to the theoretical maximum, effectively destroys the correlation between pixels, and demonstrates high sensitivity to variations in the input data. The proposed scheme shows very good feasibility in terms of both security and efficiency, which gives a reliable solution for secure image transmission and storage. This is proven by a study of resistance to various crypto–graphic attacks such as brute force attack, differential attack, noise and data cut attacks, key sensitivity, and computational complexity.
1 January 2021 in IOP Conference Series: Materials Science and Engineering
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Conference Paper
Open access
PDF file
SSStanimir Mihaylov Sadinov
Stanimir Mihaylov Sadinov
KAKrasen Angelov
Krasen Angelov
PKP Kogias
P Kogias
Passive optical networks are emerging as the main technology for building access networks. The current metropolitan optical communication networks operate at 1Gbps, which appears to be insufficient for the future development and exponential growth of traffic from IP services. The existing various traffic-intensive services and the growing interest in 4K video content and streaming services require the introduction of new solutions within passive optical networks (PON). A promising option is the combination of 10 Gbps and above high-speed data transmission with spectral multiplexing. DWDM will provide the required high spectral efficiency, but in contrast will require the use of a proper modulation scheme to achieve a longer distance. In this paper a model for performance analysis and solving optimization problems for DWDM-PON networks is developed. Different signal modulations are considered and a comparative analysis is performed. The behaviour of the system at different input parameters is modelled. Performance analysis is performed by evaluating the spectral characteristics and values of BER and Q-factor.
1 September 2017
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Conference Paper
Closed access
SSStanimir Mihaylov Sadinov
Stanimir Mihaylov Sadinov
KAKrasen Angelov
Krasen Angelov
PKPANAGIOTIS KOGIAS
PANAGIOTIS KOGIAS
MMMichail Nikolaos Malamatoudis
Michail Nikolaos Malamatoudis
Optical WDM networks use high-speed optical trunk lines as backbone network. The maximum number of amplifying sections in the optical line is causally related to power budget, dispersive expansion of code pulses and nonlinear distortions. All parameters are closely correlated. Total signal losses are estimated and through series of iterations a solution is found which for a given number of amplifying sections for the current iteration will yield minimum relative percentage error. A simulation model is developed to validate the proposed approach.
1 September 2017
Verified
Conference Paper
Closed access
RRRostislav Rusev
Rostislav Rusev
GAGeorge Angelov
George Angelov
KAKrasen Angelov
Krasen Angelov
DNDimitar Nikolov Nikolov
Dimitar Nikolov Nikolov
This paper, presents a model to predict the energy output from reverse electrowetting energy harvesting system with use of cost-effective materials. Reverse electrowetting on dielectric allows energy to be harvested from spontaneous aperiodic mechanical movements, where conventional energy harvesting approaches are not suitable for due to low energy conversion efficiency and frequency.
9 August 2024 in Engineering Proceedings
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Conference Paper
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NMNikolay Manchev
Nikolay Manchev
KAKrasen Angelov
Krasen Angelov
SSStanimir Mihaylov Sadinov
Stanimir Mihaylov Sadinov
PKPANAGIOTIS KOGIAS
PANAGIOTIS KOGIAS
When building energy-efficient communication platforms for IoT, it is necessary to plan in advance a number of actions related to radio coverage and to anticipate possible problems to be solved before building the platform. Since all data traffic is transmitted wirelessly, it should provide reliable and quality radio coverage. Designing long-range LoRaWAN communications in outdoor environments with complex terrain is a challenging task that involves determining the correct location and height of the gateway to provide the necessary line-of-sight and minimize communication with reflected signals, as well as the appropriate equipment (e.g., transceiver antennas and radio modules). This article discusses the planning and research of such a type of radio coverage. For evaluation, the following were used: determining the coverage range and measuring the signal parameters, taking into account the receiver sensitivity; control of communication parameters; measurements and analysis in order to detect and eliminate existing disturbances and issues; and assessment of the quality of the service through survey and continuous monitoring in the coverage area.