Efficient Advanced Encryption Standard for Securing Cognitive Radio Networks

During the last decade, the CR (Cognitive Radio) came into view as a major wireless technology to resolve the issue of spectrum secrecy and efficient spectrum utilization. However, due to unlicensed (secondary) users, there are various security threats to the CRN (Cognitive Radio Networks). Some malicious users may access the CRN and mislead the secondary users to vacate the occupied channel, which may stop the communication. In this work, we propose a new cryptographic-based algorithm, CRAES (Cognitive Radio-Advanced Encryption Standard), inspired by the traditional AES to secure the CRN. The data of the primary and secondary users is encrypted at the transmitter and decrypted at the receiver. Unlike the conventional AES, we introduce the data-dependent key-generation and shift-rows process. We also reduce the rounds of AES from 10-6 to improve the computational efficiency without compromising the overall security. The experimental results demonstrate the effectiveness of the proposed CR-AES in terms of better security, reliability, and computational efficiency

DISEÑO E IMPLEMENTACIÓN DE UN PROTOTIPO DE MONITOREO DE BAJO COSTO PARA ESTACIONES DE RADIODIFUSIÓN SONORA EN FRECUENCIA MODULADA (DESIGN AND IMPLEMENTATION OF A LOW COST PROTOTYPE TO MONITOR FREQUENCY MODULATION IN BROADCAST RADIO STATIONS)

Resumen Es necesario tener instrumentos para evaluar la operación de sistemas de radiodifusión sonora, y verificar el cumplimiento de los parámetros de operación otorgados por las agencias encargadas de administrar el espectro radioeléctrico. Este artículo presenta el proceso de diseño, implementación y pruebas de calibración y operación de un prototipo de monitoreo de bajo costo para estaciones de radiodifusión sonora en frecuencia modulada, utilizando radio definido por software. Este proceso adaptó la metodología de Programación Extrema, la cual define análisis de requerimientos, diseño, implementación y evaluación del prototipo. El prototipo empleó un dispositivo periférico de radio universal, fue calibrado mediante equipos especializados y se utilizó para evaluar los parámetros de operación de la estación Unicauca Estéreo de la Universidad del Cauca en Popayán. La evaluación permitió concluir que el prototipo ofrece la posibilidad de realizar el monitoreo de los parámetros esenciales de las estaciones de FM de forma sencilla y confiable. Palabras Clave: Prototipo de monitoreo de bajo costo, radio definido por software, radiodifusión sonora en frecuencia modulada. Abstract There is a need to have instruments to evaluate the operation of radio broadcast systems, and thereby to verify and ensure the operating parameters granted by the respective radio spectrum national agency. This article presents the process of designing, implementing, calibrating, and operating a low-cost monitoring prototype for FM radio broadcast stations using software-defined radio (SDR). This process applied the extreme programming (XP) methodology, which defines activities related to requirement analysis, design, implementation, and evaluation of the prototype's operation. The implemented prototype used a universal radio peripheral device (USRP), which offered results comparable to specialized equipment. The monitoring prototype was calibrated using specialized radio frequency laboratory equipment and was used to evaluate and analyze the operating parameters of the Unicauca Estéreo, a university radio station at the Universidad del Cauca in Popayán, Colombia. The evaluation allowed us to conclude that the prototype offers the possibility to monitor the essential parameters of an FM broadcast radio station easily and confidently. Keywords: FM broadcast radio stations, low cost prototype monitor, software define radio

Μαθηματική Μοντελοποίηση και Ανάλυση δικτύων 5ης Γενιάς

Στην εργασία που ακολουθεί έγινε μια προσπάθεια μελέτης, μαθηματικής ανάλυσης και μοντελοποίησης των ασύρματων κινητών δικτύων 5ης γενιάς. Στο πρώτο κεφάλαιο παρουσιάζονται τα κίνητρα ανάπτυξης μιας νέας τεχνολογικής γενιάς. Γίνεται μια επισκόπηση των προϋποθέσεων και των προκλήσεων που έχει να αντιμετωπίσει η γενιά 5G. Παρουσιάζονται οι σκοποί και οι στόχοι που έχουν θέσει διαφορετικοί οργανισμοί προτυποποίησης. Αναλύονται οι αρχιτεκτονικές και οι τεχνολογίες που χρησιμοποιούνται ήδη από τα υπάρχοντα ασύρματα κινητά δίκτυα. Τέλος, παρουσιάζονται επιγραμματικά τα βασικά ερευνητικά προγράμματα για το «πέρασμα» στα δίκτυα της 5ης γενιάς. Στο δεύτερο κεφάλαιο παρουσιάζονται τα σημαντικά εργαλεία, οι μετρικές και τα μεγέθη που μπορούν να υπολογίζουν οι σταθμοί βάσης και οι συσκευές ώστε να αξιολογούν την ποιότητα της επικοινωνίας σε ένα ασύρματο δίκτυο. Αναλύονται κάποιες βασικές οικογένειες στοχαστικών διεργασιών οι οποίες μοντελοποιούν τις θέσεις των συσκευών στον χώρο και αξιοποιώντας τις μαθηματικές τους ιδιότητες και τα θεωρήματα της στοχαστικής γεωμετρίας εξάγουν πληροφορίες για τις μετρικές των δικτύων. Στο τέλος του κεφαλαίου παρουσιάζεται μια κριτική σύγκριση ώστε να διαχωρίσουμε τα οφέλη κάθε διεργασίας και τις πρακτικές τους εφαρμογές στα ασύρματα δίκτυα. Στο τρίτο κεφάλαιο αναλύονται κάποιες ενδεικτικές εργασίες οι οποίες περιγράφονται μέσω της στοχαστικής γεωμετρίας και βρίσκουν εφαρμογή σε συγκεκριμένους τύπους δικτύων εξάγοντας ενδιαφέροντα αποτελέσματα για τις μετρικές και «επιλύοντας» κάποια ανοιχτά προβλήματα των δικτύων προηγούμενης γενιάς.In the following work there is an attempt to study, analyze and model the 5th generation of wireless mobile networks. The first chapter presents the incentives to develop a new technology generation. There is an overview of the conditions and challenges that the 5G generation has to face. The aims and objectives set by different standardization organizations are presented. It analyzes the architectures and technologies already used by existing wireless mobile networks. Finally, we present in brief the basic research projects that explore the technological options of 5th generation networks. The second chapter presents the important tools and metrics that base stations and devices can calculate to measure the quality of experience in a wireless network. We analyze some basic stochastic processes that model the positions of the devices in the space. These processes exploit mathematical properties and theorems of stochastic geometry and derive information about the network metrics. At the end of the chapter we compare the processes in order to separate the benefits of each one and the practical applications to wireless networks. In the third chapter we analyze some indicative papers that are described through stochastic geometry and find application in specific types of networks. We export interesting results for the metrics and find solutions on some open problems and challenges of the previous generation networks

Optimal Power Allocation for Energy Efficient MIMO Relay Systems in 5G Wireless Communication

Wireless communication has undergone a significant growth to meet the unexpected demand of wireless data traffic over the past two decades. As manifested by the revolution of the third and fourth generations and long-term evolution advanced (LTE-A), engineers and researchers have been devoted to the development of the next-generation (5G) wireless solutions to meet the anticipated demand of 2020. To this end, cooperative relay communication has been introduced as an enabling technology to increase the throughput and extend the coverage of the broadband wireless networks. Decode-and-forward (DF) has been known as an effective cooperative relaying strategy for its outstanding features. On the other hand, merging massive multi-input-multi-output (MIMO) with cooperative DF relay is considered as a key technology for 5G wireless networks to improve the quality-of-service (QoS) in a cost-effective manner. The objective of this thesis is to establish and solve a power allocation optimization problem for energy efficient multi-pair DF relay systems integrated with massive MIMO. The first part of the thesis is focused on a constrained optimization problem to minimize the total transmit power for each transmission phase of the DF relay. Due to the non-convexity characteristic, the objective function is approximated as a convex function by means of complementary geometric programming (CGP) which is then solved by a sequence of geometric programming (GP). A lower bound of average SINR is also introduced by adopting the MMSE channel state information (CSI) to relax the constraint functions in the standard GP form. Finally, we proposed a homotopy or continuation method based algorithm to solve the optimization problem via popular CVX optimization toolbox. MATLAB simulations are conducted to validate the proposed algorithm. In the second part, another optimization problem is presented for the entire two-hop transmission of the DF relay to improve the global energy efficiency (GEE) under different channel conditions. Here, we estimate the channel by maximum likelihood (ML) criterion and investigate a closed-form expression of GEE. Further, GEE is approximated in a convex form by applying CGP due to the difficulty arising from the non-convexity and a lower bound of the average SINR expression is also derived to relax the constraint functions in the GP problem. Numerical results showing a detailed comparison of GEE under ML and MMSE channel estimation conditions and the performance improvement from the proposed algorithm are provided