Engineering Commons^™

A Stochastic Spectrum Trading And Resource Allocation Framework For Opportunistic Dynamic Spectrum Access Networks, Mohamed Abdelraheem, Mohammad Mahmoud Abdellatif

Electrical Engineering

In this article, the spectrum trading problem between primary users and secondary networks is investigated. The secondary network requests multiple channels with the targeted availability to satisfy its users’ demands. Due to the uncertainty about the channels availability, stochastic optimization techniques are adopted to find the optimal set of channels for each secondary network for the lowest cost. Two different constraints on the secondary demand are defined. The first one is when the throughput has to be fully satisfied for a certain percentage of time, and the second one is when the expected value of the throughput has to exceed …

Frequency Agile Ofdm System For Radio Communication In High Frequency Bands, Erin E. Hill

Electrical & Computer Engineering Theses & Dissertations

High Frequency (HF) radio communication existed as the primary source of over-the-horizon communication for decades prior to the wide implementation of satellite and cellular networks. Even today, should satellite communication become unavailable, the robust backup of HF vitally supports long distance data transmission without the need of a cellular infrastructure. This capability is of particular importance to naval applications while at sea. Frequency choice, however, becomes critical in supporting reliable HF communication as too high of a frequency will not return to earth and too low of a frequency will result in high absorption rates within the atmosphere. A potential …

Case Study Of Tv Spectrum Sensing Model Based On Machine Learning Techniques, Abdalaziz Mohammad, Faroq Ali Awin, Esam Abdel-Raheem

Electrical and Computer Engineering Publications

Spectrum sensing is an essential component in cognitive radios (CR). Machine learning (ML) algorithms are powerful techniques for designing a promising spectrum sensing model. In this work, the supervised ML algorithms, support vector machine (SVM), k-nearest neighbor (kNN), and decision tree (DT) are applied to detect the existence of primary users (PU) over the TV band. Moreover, the Principal Component Analysis (PCA) is incorporated to speed up the learning of the classifiers. Furthermore, the ensemble classification-based approach is employed to enhance the classifier predictivity and performance. Simulation results have shown that the highest performance is achieved by the ensemble classifier. …

Spectrum Sensing With Energy Detection In Multiple Alternating Time Slots, Călin Vlădeanu, Alexandru Marţian, Dimitrie C. Popescu

Electrical & Computer Engineering Faculty Publications

Energy detection (ED) represents a low complexity approach used by secondary users (SU) to sense spectrum occupancy by primary users (PU) in cognitive radio (CR) systems. In this paper, we present a new algorithm that senses the spectrum occupancy by performing ED in K consecutive sensing time slots starting from the current slot and continuing by alternating before and after the current slot. We consider a PU traffic model specified in terms of an average duty cycle value, and derive analytical expressions for the false alarm probability (FAP) and correct detection probability (CDP) for any value of K . Our …

An Investigation Into Cognitive Radio System Performance, Courtney Hardy, Lucas F. Feather, William S. Guy

Honors Theses

The objective of this thesis is to explore cognitive radio performance through an in-depth literature review and an implementation of a software-defined radio prototyping system. Specifically, this thesis investigates the spectrum-sensing aspect of cognitive radio by comparing two spectrum-sensing methods. It was found in the literature review that a system utilizing matched filter detection would provide higher probability of detection in low signal-to-noise ratio environments when compared to a system utilizing energy detection. These spectrum sensing methods were thus implemented and compared in the cognitive radio systems presented in this thesis. Additionally, experiments were conducted to determine the most efficient …

Three-Event Energy Detection With Adaptive Threshold For Spectrum Sensing In Cognitive Radio Systems, Alexandru Martian, Mahmood Jalal Ahmad Al Sammarraie, Calin Vladeanu, Dimitrie Popescu

Electrical & Computer Engineering Faculty Publications

Implementation of dynamic spectrum access (DSA) in cognitive radio (CR) systems requires the unlicensed secondary users (SU) to implement spectrum sensing to monitor the activity of the licensed primary users (PU). Energy detection (ED) is one of the most widely used methods for spectrum sensing in CR systems, and in this paper we present a novel ED algorithm with an adaptive sensing threshold. The three-event ED (3EED) algorithm for spectrum sensing is considered for which an accurate approximation of the optimal decision threshold that minimizes the decision error probability (DEP) is found using Newton’s method with forced convergence in one …

Robust Secure Wireless Powered Miso Cognitive Mobile Edge Computing, Boyang Liu, Jiajia Song, Jin Wang, Haijan Sun, Qun Wang

Electrical and Computer Engineering Student Research

Wireless power transfer (WPT) and cognitive radio (CR) are two promising techniques in designing mobile-edge computing (MEC) systems. In this paper, we study a robust secure wireless powered multiple-input single-output (MISO) cognitive MEC system, which integrates several techniques: physical-layer security, WPT, CR, underlay spectrum sharing and MEC. Three optimization problems are formulated to minimize the total transmission power (TTP) of the primary transmitter (PT) and the secondary base station (SBS) under perfect channel state information (CSI) model, bounded CSI error model and the probabilistic CSI error model, respectively. The formulated problems are nonconvex and hard to solve. Three two-phase iterative …

A Hop-By-Hop Relay Selection Strategy In Multi-Hop Cognitive Relay Networks, Hui Sun, Mort Naraghi-Pour, Weixing Sheng, Renli Zhang

Faculty Publications

In this paper, a hop-by-hop relay selection strategy for multi-hop underlay cognitive relay networks (CRNs) is proposed. In each stage, relays that successfully decode the message from previous hop form a decoding set. Taking both maximum transmit power and maximum interference constraints into consideration, the relay in the decoding set which has the largest number of channels with an acceptable signal-to-noise ratio (SNR) level to the relays in the next stage is selected for retransmission. Therefore, relay selection in each stage only relies on channel state information (CSI) of the channels in that stage and does not require the CSI …

A Multibeam Subarrayed Time-Modulated Linear Array, Uğur Yeşi̇lyurt, İhsan Kanbaz, Ertuğrul Aksoy

Turkish Journal of Electrical Engineering and Computer Sciences

In conventional time-modulated arrays (TMAs), because of the usage of the RF-switch, harmonics are generated at multiples of the modulation frequency. In this study, the synthesis of time-modulated arrays has been analyzed for cognitive radio (CR) systems, in which these harmonics are suitably exploited for more efficient utilization of the spectrum. In order to accomplish the desired pattern at requested harmonic frequencies, a new excitation strategy with sinusoidal signals is proposed. The use of sinusoidal waveforms creates independent beams, allowing independent steering capability. Moreover, by utilizing the subarray structure, it is possible to have a smaller number of excitation functions …

A Secure And Energy-Aware Approach For Cognitive Radio Communications, Haitham Khaled, Iftekhar Ahmad, Daryoush Habibi, Quoc Viet Phung

Research outputs 2014 to 2021

The cognitive radio (CR) technique has revealed a novel way of utilizing the precious radiospectrum via allowing unlicensed users to opportunistically access unutilized licensed bands. Using sucha technique enables agile and flexible access to the radio spectrum and can resolve the spectrum-scarcityproblem and maximize spectrum efficiency. However, two major impediments have been limiting thewidespread adoption of cognitive radio technology. The software-defined radio technology, which is theenabling technology for the CR technique, is power-hungry and this raises a major concern for battery-constrained devices such as smart phones and laptops. Secondly, the opportunistic and open nature ofthe CR can lead to major …

Performance Of Cognitive Radio Networks With Unknown Dynamic Primary User Signals, Sara L. Macdonald

Electrical & Computer Engineering Theses & Dissertations

The current static assignment of RF spectrum in the United States and other parts of the world has led to a large portion of the RF spectrum to be geographically and temporally underutilized. While the amount of RF spectrum is finite, the demand for spectrum continues to increase making it necessary to increase utilization of many bands. Several innovative methods for allowing licensed primary users (PUs) to share spectrum with unlicensed secondary users (SUs) have being proposed. Of these methods Cognitive Radio (CR) has emerged as a promising technology that enables SUs to dynamically access spectrum after first sensing the …

A Compact Wide-Slot Uwb Antennawith Reconfigurable And Sharp Dual-Band Notches For Underlay Cognitive Radioapplications, Falih Alnahwi, Abdulghafor Abdulhameed, Husham Swadi, Abdulkareem Abdullah

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents a compact wide-slot ultrawide-band (UWB) antenna with reconfigurable and sharp dual-band notches compatible with the underlay cognitive radio systems. The antenna slot and tuning stub are reshaped in such a way that the proposed antenna operating bandwidth extends along the frequency band specified for UWB applications (3.1-10.6 GHz). In spite of their sharpness, the generated band notches perfectly cancel the interference with the entire 5 GHz wireless local area network (WLAN) frequency band (5.15-5.725 GHz) and that of the military X-band satellite communications downlink (7.25-7.745 GHz). The WLAN band notch is presented by attaching a pair of …

Performance Improvement Of Multiuser Cognitive Relay Networks With Full-Duplex Cooperative Sensing And Energy Harvesting, Alieh Moradi, Hamid Farrohki

Turkish Journal of Electrical Engineering and Computer Sciences

Energy harvesting cognitive radio has been considered as a promising technology in the fifth generation (5G) of wireless networks to solve the lack of spectrum and energy. In this paper, a novel wireless energy harvesting relay network is proposed for a multiuser cognitive radio to obtain the maximum throughput and decrease the false alarm and misdetection probabilities. The secondary user (SU) can harvest energy from solar sources while utilizing the licensed spectrum of the primary user (PU). Cooperative spectrum sensing is applied to improve the performance of the secondary network and decrease collision and sensing time. In this paper, the …

Bio-Socially Inspired Strategies In Support Of Dynamic Spectrum Access: An Evolutionary Game Theory Perspective, Mohammad Ali Marzoug Abu Shattal

Dissertations

Dynamic Spectrum Access (DSA) has been introduced to fulfill the expanded need for spectrum by different wireless networks and applications. Within the realm of spectrum access, the problem of "spectrum crunch" is present since some of the spectrum bands are overcrowded and others are underutilized. DSA aims to alleviate the problem of spectrum crunch. In DSA, Primary Users (PUs) allow Secondary Users (SUs) to access the spectrum as long as they do not interfere with PU transmissions beyond a pre-agreed acceptable level. In this work, a bio-socially inspired approach is proposed for SU interactions in support of better throughput for …

Recurrent Neural Networks And Matrix Methods For Cognitive Radio Spectrum Prediction And Security, Alexander M. Glandon

Electrical & Computer Engineering Theses & Dissertations

In this work, machine learning tools, including recurrent neural networks (RNNs), matrix completion, and non-negative matrix factorization (NMF), are used for cognitive radio problems. Specifically addressed are a missing data problem and a blind signal separation problem. A specialized RNN called Cellular Simultaneous Recurrent Network (CSRN), typically used in image processing applications, has been modified. The CRSN performs well for spatial spectrum prediction of radio signals with missing data. An algorithm called soft-impute for matrix completion used together with an RNN performs well for missing data problems in the radio spectrum time-frequency domain. Estimating missing spectrum data can improve cognitive …

A Frequency-Reconfigurable Elliptical Monopole Antenna For Cognitive Radio Networks, Santasri Koley, Debjani Mitra

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, an elliptical disk monopole antenna with seven switchable states, including an ultrawideband (UWB) state and six narrowband states, is presented. It consists of an elliptical disk radiator to operate in the UWB mode for cognitive radio (CR) sensing. To operate in the narrowband mode, the antenna is fed through a defected ground structure (DGS) integrated microstrip line. Frequency reconfigurability is achieved by changing the DGS slot length using six electronic switches. The simple proposed design can cover a wide range of frequency bands from 0.75 to 12 GHz, has an omnidirectional radiation pattern with high gain, and …

Cooperative Wideband Spectrum Sensing Based On Joint Sparsity, Ghazaleh Jowkar

Theses and Dissertations

COOPERATIVE WIDEBAND SPECTRUM SENSING BASED ON JOINT SPARSITY

By Ghazaleh Jowkar, Master of Science

A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science at Virginia Commonwealth University

Virginia Commonwealth University 2017

Major Director: Dr. Ruixin Niu, Associate Professor of Department of Electrical and Computer Engineering

In this thesis, the problem of wideband spectrum sensing in cognitive radio (CR) networks using sub-Nyquist sampling and sparse signal processing techniques is investigated. To mitigate multi-path fading, it is assumed that a group of spatially dispersed SUs collaborate for wideband spectrum sensing, to determine whether or not …

Single Carrier Frequency Domain Equalization And Energy Efficiency Optimization For Mimo Cognitive Radio., Xiaohui Zhang

Electronic Theses and Dissertations

This dissertation studies two separate topics in wireless communication systems. One topic focuses on the Single Carrier Frequency Domain Equalization (SC-FDE), which is a promising technique to mitigate the multipath effect in the broadband wireless communication. Another topic targets on the energy efficiency optimization in a multiple input multiple output (MIMO) cognitive radio network. For SC-FDE, the conventional linear receivers suffer from the noise amplification in deep fading channel. To overcome this, a fractional spaced frequency domain (FSFD) receiver based on frequency domain oversampling (FDO) is proposed for SC-FDE to improve the performance of the linear receiver under deep fading …

Physical Layer Defenses Against Primary User Emulation Attacks, Joan A. Betances

Theses and Dissertations

Cognitive Radio (CR) is a promising technology that works by detecting unused parts of the spectrum and automatically reconfiguring the communication system's parameters in order to operate in the available communication channels while minimizing interference. CR enables efficient use of the Radio Frequency (RF) spectrum by generating waveforms that can coexist with existing users in licensed spectrum bands. Spectrum sensing is one of the most important components of CR systems because it provides awareness of its operating environment, as well as detecting the presence of primary (licensed) users of the spectrum.

A Slotted Aloha-Based Cognitive Radio Network Under Capture Effect In Rayleigh Fading Channels, Muhammed Enes Bayrakdar, Sedat Atmaca, Alper Karahan

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, a slotted ALOHA-based cognitive radio (CR) network is proposed and the throughput performance of the proposed CR network model under Rayleigh fading channels is examined. Our CR network contains two special groups of users, primary users (PUs) and CR users (CRUs), and they are considered to be sharing a time-slotted-based common communication channel. While PUs can access the channel at any time owing to their legal right, CRUs can only access the channel when it is not occupied by the PUs. In the network model developed, PUs access the channel utilizing time division multiple access as a …

Analysis Of The Fm Radio Spectrum For Secondary Licensing Of Low-Power Short-Range Cognitive Internet Of Things Devices, Derek T. Otermat, Ivica Kostanic, Carlos E. Otero

Electrical Engineering and Computer Science Faculty Publications

The analysis presented in this paper indicates that the FM radio spectrum is underutilized in the areas of the continental United States that have a population of 100000 or less. These locations have vacant FM radio spectrum of at least 13 MHz with sufficient spectrum spacing between adjacent FM radio channels. The spectrum spacing provides the required bandwidth for data transmission and provides enough bandwidth to minimize interference introduced by neighboring predicted and unpredicted FM radio stations and other low-power short-range Internet of Thing (IoT) devices. To ensure that low-power short-range IoT devices maintain reliable communications vacant radio spectrum, such …

Design, Analysis, Implementation And Evaluation Of Real-Time Opportunistic Spectrum Access In Cloud-Based Cognitive Radio Networks, Nimish Sharma

Electronic Theses and Dissertations

Opportunistic spectrum access in cognitive radio network is proposed for remediation of spectrum under-utilization caused by exclusive licensing for service providers that are intermittently utilizing spectrum at any given geolocation and time. The unlicensed secondary users (SUs) rely on opportunistic spectrum access to maximize spectrum utilization by sensing/identifying the idle bands without causing harmful interference to licensed primary users (PUs). In this thesis, Real-time Opportunistic Spectrum Access in Cloud-based Cognitive Radio Networks (ROAR) architecture is presented where cloud computing is used for processing and storage of idle channels. Software-defined radios (SDRs) are used as SUs and PUs that identify, report, …

Spectrum Allocation In Networks With Finite Sources And Data-Driven Characterization Of Users' Stochastic Dynamics, Ahsan-Abbas Ali

LSU Doctoral Dissertations

During emergency situations, the public safety communication systems (PSCSs) get overloaded with high traffic loads. Note that these PSCSs are finite source networks. The goal of our study is to propose techniques for an efficient allocation of spectrum in finite source networks that can help alleviate the overloading of PSCSs. In a PSCS, there are two system segments, one for the system-access control and the other for communications, each having dedicated frequency channels. The first part of our research, consisting of three projects, is based on modeling and analysis of finite source systems for optimal spectrum allocation, for both access-control …

On The Improvement Of The Capacity Of The Heterogeneous Networks With Link-Level And System-Level Approaches, Mehmet Bahadır Çelebi

USF Tampa Graduate Theses and Dissertations

Evolution of wireless services enabled the development of the advanced applications and shifted the paradigms of research in this field from voice to data centric. Such services are spreading like wildfire between users and hence, increasing the demand for large bandwidth. However, the frequency spectrum that is suitable for wireless mobile communications is already assigned to particular services from 400 MHz to several GHz. Also, allocating a large chunk of band continuously from the same part of the spectrum may not be possible due to spectral crowd. Therefore, meeting the demand for high data rate requiring wireless services within the …

Detection Of Ofdm Signals Using Pilot Tones And Applications To Spectrum Sensing For Cognitive Radio Systems, Ahmed Temtam

Electrical & Computer Engineering Theses & Dissertations

Nowadays there are an increasing number of wireless devices which support wireless networking and the need for higher data rate communication is increasing rabidly. As more and more systems go wireless, approaching technologies will face spectral crowding and existence of wireless devices will be an important issue. Because of the limited bandwidth availability, accepting the request for higher capacity and data rates is a challenging task, demanding advanced technologies that can offers new methods of using the available radio spectrum. Cognitive radio introduces a key solution to the spectral increasing issue by presenting the opportunistic usage of spectrum that is …

Spectrum Sensing, Spectrum Monitoring, And Security In Cognitive Radios, Erfan Soltanmohammadi

LSU Doctoral Dissertations

Spectrum sensing is a key function of cognitive radios and is used to determine whether a primary user is present in the channel or not. In this dissertation, we formulate and solve the generalized likelihood ratio test (GLRT) for spectrum sensing when both primary user transmitter and the secondary user receiver are equipped with multiple antennas. We do not assume any prior information about the channel statistics or the primary user’s signal structure. Two cases are considered when the secondary user is aware of the energy of the noise and when it is not. The final test statistics derived from …

On Spectrum Probing In Cognitive Radio Networks: Does Randomization Matter, Chao Chen, Zesheng Chen, Todor Cooklev, Carlos Pomalaza-Ráez

Todor Cooklev

In cognitive radio networks, dynamic spectrumaccess is achieved by allowing secondary users (SUs) to probethe spectrum and utilize available channels opportunistically.Spectrum probing mechanisms should be efficient and fast toavoid harmful interference with primary users (PUs). Periodicprobing has been commonly adopted as a default spectrumprobing mechanism. In this paper, we attempt to study differentspectrum probing mechanisms and evaluate a performance metriccalled the probing delay, i.e., how quickly a probing mechanismcan detect a channel change. We find that randomization in theprobing strategy does affect the probing delay. Specifically, in theindependent sensing scenario, periodic probing indeed achievesthe smallest probing delay. In the cooperative …

Describing Radio Hardware And Software Using Owl For Over-The-Air Software Download, Todor Cooklev, Stanchev, David Clendenen

Todor Cooklev

Recently, several researchers have discovered the need for radios to use description techniques. Previous research describes information such as the current frequency band, waveform, and so on. However, this information is presented at a level that is not sufficient to determine software/hardware compatibility for over-the-air software download. For example, a device should not attempt to download a wideband waveform if its radio front-end is only narrowband, or if its baseband hardware cannot provide the required MIPS for the new waveform. Over-the-air software download is one of the most interesting features of software-defined radios. The compatibility between software and hardware prior …

An Investigation Of Security Challenges In Cognitive Radio Networks, Deepraj S. Vernekar

Computer and Electronics Engineering: Dissertations, Theses, and Student Research

The recent advances in wireless communication have led to the problem of growing spectrum scarcity. The available wireless spectrum has become scarcer due to increasing spectrum demand for new wireless applications. The large portion of the allocated spectrum is sporadically used leading to underutilization of significant amount of spectrum. To improve the spectrum efficiency, the idea of cognitive radio technology was introduced. This concept of cognitive radio provides a promising solution for the spectrum scarcity issues in wireless networks. Meanwhile, the security issues of cognitive radio have received more attentions recently since the inherent properties of CR networks would pose …

Optimization And Learning In Energy Efficient Cognitive Radio System, Kun Zheng

Doctoral Dissertations

Energy efficiency and spectrum efficiency are two biggest concerns for wireless communication. The constrained power supply is always a bottleneck to the modern mobility communication system. Meanwhile, spectrum resource is extremely limited but seriously underutilized.

Cognitive radio (CR) as a promising approach could alleviate the spectrum underutilization and increase the quality of service. In contrast to traditional wireless communication systems, a distinguishing feature of cognitive radio systems is that the cognitive radios, which are typically equipped with powerful computation machinery, are capable of sensing the spectrum environment and making intelligent decisions. Moreover, the cognitive radio systems differ from traditional wireless …