arXiv subjects

Vasileios M. Kapinas

Publications and source records attributed to Vasileios M. Kapinas.

6 recordsLinked to original sources

arXiv2018

Dynamic Spectrum Sensing Through Accelerated Particle Swarm Optimization

In this paper, a novel optimization algorithm, called the acceleration-aided particle swarm optimization (AAPSO), is proposed for reliable dynamic spectrum sensing in cognitive radio networks. In A-APSO, the acceleration variable of the particles in the swarm is also considered in the search space of the optimization problem. We show that the proposed A-APSO based spectrum sensing technique is more efficient in terms of performance than the corresponding one based on the standard particle swarm optimization algorithm.

math.OC↗

arXiv2016

Securing the MIMO Wiretap Channel with Polar Codes and Encryption

Polar codes have been proven to be capacity achieving for any binary-input discrete memoryless channel, while at the same time they can reassure secure and reliable transmission over the single-input single-output wireless channel. However, the use of polar codes to secure multiple-antenna transmission and reception has not yet been reported in the open literature. In this paper, we assume a multiple-input multiple-output wiretap channel, where the legitimate receiver and the eavesdropper are equipped with the same number of antennas. We introduce a protocol that exploits the properties of both physical and media access control layer security by employing polar coding and encryption techniques in a hybrid manner in order to guarantee secure transmission. A novel security technique is also proposed, where a cryptographic key is generated based on the information transmitted and renewed every transmission block without the need for a separate key exchange method. Finally, to illustrate the effectiveness of the proposed protocol, we prove the weak and strong security conditions, and we provide a practical method to achieve computational security for the cases where these conditions cannot be established.

cs.IT↗

arXiv2016

I/Q-Imbalance Self-Interference Coordination

In this paper, we present a novel low-complexity scheme, which improves the performance of single-antenna multi-carrier communication systems, suffering from in-phase and quadrature (I/Q)-imbalance (IQI) at the receiver. We refer to the proposed scheme as I/Q-imbalance self-interference coordination (IQSC). IQSC does not only mitigate the detrimental effects of IQI, but, through appropriate signal processing, also coordinates the self-interference terms produced by IQI in order to achieve second-order frequency diversity. However, these benefits come at the expense of a reduction in transmission rate. More specifically, IQSC is a simple transmit diversity scheme that improves the signal quality at the receiver by elementary signal processing operations across symmetric (mirror) pairs of subcarriers. Thereby, the proposed transmission protocol has a similar complexity as Alamouti's space-time block coding scheme and does not require extra transmit power nor any feedback. To evaluate the performance of IQSC, we derive closed-form expressions for the resulting outage probability and symbol error rate. Interestingly, IQSC outperforms not only existing IQI compensation schemes but also the ideal system without IQI for the same spectral efficiency and practical target error rates, while it achieves almost the same performance as ideal (i.e., IQI-free) equal-rate repetition coding. Our findings reveal that IQSC is a promising low-complexity technique for significantly increasing the reliability of low-cost devices that suffer from high levels of IQI.

cs.IT↗

arXiv2015

Non-Orthogonal Multiple Access for Visible Light Communications

The main limitation of visible light communication (VLC) is the narrow modulation bandwidth, which reduces the achievable data rates. In this paper, we apply the non-orthogonal multiple access (NOMA) scheme to enhance the achievable throughput in high-rate VLC downlink networks. We first propose a novel gain ratio power allocation (GRPA) strategy that takes into account the users' channel conditions to ensure efficient and fair power allocation. Our results indicate that GRPA significantly enhances system performance compared to the static power allocation. We also study the effect of tuning the transmission angles of the light emitting diodes (LEDs) and the field of views (FOVs) of the receivers, and demonstrate that these parameters can offer new degrees of freedom to boost NOMA performance. Simulation results reveal that NOMA is a promising multiple access scheme for the downlink of VLC networks.

cs.IT↗

arXiv2015

Big Data Analytics for Dynamic Energy Management in Smart Grids

The smart electricity grid enables a two-way flow of power and data between suppliers and consumers in order to facilitate the power flow optimization in terms of economic efficiency, reliability and sustainability. This infrastructure permits the consumers and the micro-energy producers to take a more active role in the electricity market and the dynamic energy management (DEM). The most important challenge in a smart grid (SG) is how to take advantage of the users' participation in order to reduce the cost of power. However, effective DEM depends critically on load and renewable production forecasting. This calls for intelligent methods and solutions for the real-time exploitation of the large volumes of data generated by a vast amount of smart meters. Hence, robust data analytics, high performance computing, efficient data network management, and cloud computing techniques are critical towards the optimized operation of SGs. This research aims to highlight the big data issues and challenges faced by the DEM employed in SG networks. It also provides a brief description of the most commonly used data processing methods in the literature, and proposes a promising direction for future research in the field.

cs.DB↗

arXiv2015

Solar Lab Notebook (SLN): An Ultra-Portable Web-Based System for Heliophysics and High-Security Labs

This paper introduces the Solar Lab Notebook (SLN), an electronic lab notebook for improving the process of recording and sharing solar related digital information in an organized manner. SLN is a pure web-based application (available online: http://umbra.nascom.nasa.gov/sln) that runs client-side only, employing a clean and very friendly graphical user interface design, and thus providing a true cross-platform user experience. Furthermore, SLN leverages unique technologies offered by modern web browsers, such as the FileReader API, the Blob interface and Local Storage mechanism; it is coded entirely using HTML5, CSS3, and JavaScript, and powered by the extremely well documented XML file format. For high-security labs, it can be utilized as an ultra-portable and secure digital notebook solution, since it is functionally self-contained, and does not require any server-side process running on either the local or a remote system. Finally, the W3C XML Schema language is used to define a list of rules, namely a data standard, that an SLN file must conform to in order to be valid. In this way, developers are able to implement their own validation functions in their projects, or use one of the freely available tools to check if a data file is properly structured. Similarly, scientific groups at different labs can easily share information, being confident about the integrity of the exchanged data.

cs.CY↗