Researcher:
Ergül, Özgür

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PhD Student

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Özgür

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Ergül

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Ergül, Özgür

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2013 - 201613

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Researcher Of Publications: search.filters.isAuthorOfPublication.9e0ea3f2-002a-4ca9-98bc-5ea7b2d1b78e

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Now showing 1 - 10 of 13
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    Throughput maximization in electromagnetic energy harvesting cognitive radio sensor networks
    (Wiley, 2016) Alagoz, Fatih; N/A; Department of Electrical and Electronics Engineering; Ergül, Özgür; Akan, Özgür Barış; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; 156793; 6647
    In the near future, billions of wireless devices are expected to be operational. To enable the required machine to machine communications, two major problems must be addressed. How to obtain the required spectrum efficiency, and how to deliver the required power to these devices. The most promising answers to these questions are cognitive radio and energy harvesting, respectively. Energy harvesting enables deployment of sensors and devices without having to worry about their battery lifetime. Cognitive radio increases the utilization of spectrum by accessing unused spectrum dynamically. Energy harvesting from electromagnetic waves is suitable for these low power, low cost devices used in machine to machine communications because only minimal additional hardware is required for such energy harvesting. With this idea as the starting point, we first present an analysis on how much throughput can be obtained from a cognitive, electromagnetic energy harvesting wireless network. Then, we show when and how cooperation among network nodes may increase performance. We believe that our results will provide insight for the development of future cooperative cognitive energy harvesting networks. Copyright (c) 2015 John Wiley & Sons, Ltd.
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    Soft handover in OFDMA based visible light communication networks
    (IEEE, 2015) N/A; N/A; Department of Electrical and Electronics Engineering; Dinç, Ergin; Ergül, Özgür; Akan, Özgür Barış; PhD Student; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 156793; 6647
    As the demand for wireless bandwidth rapidly increases, Alternative methods to radio frequency-based communication are investigated to overcome the limited bandwidth problem. Visible light communication (VLC) using light emitting diodes (LEDs) is one of these alternatives. LEDs are estimated to replace the incandescent bulbs within the decade. Since, LEDs can be intensity modulated faster than the human eye can detect, illumination and communication can both be provided by the same lighting system. indoors communication constitutes 70% of the overall traffic, and VLC is a promising technology to complement Wi-Fi and cellular wireless systems. However, proper handover mechanism should be developed for VLC to be a complete indoors solution. in this paper, we present two soft handover methods for VLC. Simulation results indicate our solutions provide higher data rate for both the overall system and individual users in the handover region.
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    Cognitive radio sensor networks in smart grid
    (Crc Press-Taylor and Francis Group, 2016) N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Ergül, Özgür; Çetinkaya, Oktay; Akan, Özgür Barış; PhD Student; Researcher; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; 156793; N/A; 6647
    Smart Grid: Networking, Data Management, and Business Models delivers a comprehensive overview of smart grid communications, discussing the latest advances in the technology, the related cyber security issues, and the best ways to manage user demand and pricing. delivers a comprehensive overview of smart grid communications, discussing the latest advances in the technology, the related cyber security issues, and the best ways to manage user demand and pricing. delivers a comprehensive overview of smart grid communications, discussing the latest advances in the technology, the related cyber security issues, and the best ways to manage user demand and pricing. 1- Delivers a comprehensive overview of smart grid communications, discussing the latest advances in the technology, the related cyber security issues, and the best ways to manage user demand and pricing. 2-Explores the space of attacks in the energy management process, the need for a smart grid simulator, and the management issues that arise around smart cities. 3-Explores the space of attacks in the energy management process, the need for a smart grid simulator, and the management issues that arise around smart cities. 4-Presents cutting-edge research on microgrids, electric vehicles, and energy trading in the smart grid. Thus, Smart Grid: Networking, Data Management, and Business Models provides a valuable reference for utility operators, telecom operators, communications engineers, power engineers, electric vehicle original equipment manufacturers (OEMs), electric vehicle service providers, university professors, researchers, and students.
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    Energy-efficient cooperative spectrum sensing for cognitive radio sensor networks
    (Ieee, 2013) N/A; Department of Electrical and Electronics Engineering; Ergül, Özgür; Akan, Özgür Barış; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; 156793; 6647
    Cognitive radio sensor network (CRSN) is an emerging sensor networking paradigm that aims to incorporate opportunistic spectrum access capability to the wireless sensor networks. Since sensor nodes are energy-constrained devices, design of efficient spectrum sensing schemes is imperative for the implementation of CRSNs. In order to address this need, a cooperative spectrum sensing scheme (CSS), specifically designed for CRSNs, is presented in this paper. CSS aims to minimize power consumption and delay during spectrum sensing, while meeting the performance requirements in terms of accuracy with minimal complexity. Simulation results indicate that significant power savings can be achieved with the proposed solution.
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    DRX and QoS-aware energy-efficient uplink scheduling for long term evolution
    (IEEE, 2013) Koç, Ali T.; N/A; Department of Economics; Department of Electrical and Electronics Engineering; Ergül, Özgür; Yılmaz, Özgür; Akan, Özgür Barış; PhD Student; Faculty Member; Faculty Member; Department of Economics; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Administrative Sciences and Economics; College of Engineering; 156793; 108638; 6647
    Discontinuous reception (DRX) is supported in 3GPP Long Term Evolution (LTE) to reduce power consumption of user equipments (UEs). Power conservation achieved via DRX can be further increased with a packet scheduler that takes DRX states into consideration. Thus, in addition to quality of service (QoS) and fairness factors, which have been the main focus so far in scheduler design, energy efficiency must also be considered in scheduling. In this paper, we introduce a DRX and QoS-aware uplink packet scheduling algorithm (DQEPS) for LTE networks. One of the main reasons of poor DRX utilization is the continuous uplink packet traffic generated by applications working in the background. Accordingly, we first lay out the cumulative distribution functions (CDF) of interpacket arrival durations constructed by inspecting uplink packet transmission for various applications. Then, we form metrics for each bearer using these CDFs along with the DRX states, QoS parameters, channel conditions, and the buffer status of the bearers. Using these metrics, we develop a scheduling algorithm for the uplink, which aims to maximize power conservation of DRX mechanism by scheduling packets in a way that tries to minimize on duration, while meeting the QoS requirements. Performance evaluations indicate that DQEPS reduces power consumption significantly compared to the previously proposed methods for LTE.
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    Routing in cognitive vehicular networks
    (CRC Press, 2016) N/A; Department of Electrical and Electronics Engineering; Ergül, Özgür; Akan, Özgür Barış; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; 156793; 6647
    In this chapter, we focus on routing in cognitive vehicular networks. Compared to other wireless networks, vehicular networks have a considerably more dynamic nature due to the speed of the vehicles. Connectivity changes rapidly as vehicles move around, as well as the channel properties due to the changes in the landscape. For the cognitive vehicular networks, another consideration is the rapid change in channel availability; as vehicles move, they go in and out of transmission range of primary users. Therefore, routing in cognitive vehicular networks is a very challenging task. We investigate conventional routing schemes in mobile ad hoc networks and also vehicular networks. We point out how they are not directly usable for cognitive vehicular networks and point out possible extensions to these schemes. We also lay out exploitable features of cognitive vehicular networks and indicate what can be done to take advantage of these feature. We investigate routing in CVNs according to various criteria such as communication paradigm, and routing approach.
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    Cooperative coarse spectrum sensing for cognitive radio sensor networks
    (Institute of Electrical and Electronics Engineers (IEEE), 2016) N/A; Department of Electrical and Electronics Engineering; Ergül, Özgür; Akan, Özgür Barış; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; 156793; 6647
    The number of applications that use industrial, scientific and medical (ISM) radio bands increase every day, creating interference problem for the wireless sensor networks (WSN) that generally operate on these bands. Cognitive radio sensor network (CRSN) has been proposed as a promising solution to this problem. However, since sensor nodes are energy-constrained devices energy efficient spectrum sensing methods are needed for CRSN. To address this need, we propose a novel cooperative coarse sensing scheme for CRSN (CC4C). CC4C is based on sequential sensing, thus, it is simple and fast. Simulation results show that CC4C incurs less sensing delay and provides significant energy conservation compared to energy detection based coarse sensing schemes, and single stage sensing schemes where no coarse sensing is performed.
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    PublicationOpen Access
    DRX and QoS-aware energy-efficient uplink scheduling for long term evolution
    (Institute of Electrical and Electronics Engineers (IEEE), 2013) Koç, Ali T.; Ergül, Özgür; Yılmaz, Özgür; Akan, Özgür Barış; PhD Student; Faculty Member; Faculty Member; College of Engineering; N/A; 108638; N/A
    Discontinuous reception (DRX) is supported in 3GPP Long Term Evolution (LTE) to reduce power consumption of user equipments (UEs). Power conservation achieved via DRX can be further increased with a packet scheduler that takes DRX states into consideration. Thus, in addition to quality of service (QoS) and fairness factors, which have been the main focus so far in scheduler design, energy efficiency must also be considered in scheduling. In this paper, we introduce a DRX and QoS-aware uplink packet scheduling algorithm (DQEPS) for LTE networks. One of the main reasons of poor DRX utilization is the continuous uplink packet traffic generated by applications working in the background. Accordingly, we first lay out the cumulative distribution functions (CDF) of interpacket arrival durations constructed by inspecting uplink packet transmission for various applications. Then, we form metrics for each bearer using these CDFs along with the DRX states, QoS parameters, channel conditions, and the buffer status of the bearers. Using these metrics, we develop a scheduling algorithm for the uplink, which aims to maximize power conservation of DRX mechanism by scheduling packets in a way that tries to minimize ON duration, while meeting the QoS requirements. Performance evaluations indicate that DQEPS reduces power consumption significantly compared to the previously proposed methods for LTE.
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    PublicationOpen Access
    Adaptive and cognitive communication architecture for next-generation PPDR systems
    (Institute of Electrical and Electronics Engineers (IEEE), 2016) Shah, Ghalib A.; Canberk, Berk; Ergül, Özgür; Akan, Özgür Barış; PhD Student; Faculty Member; College of Engineering
    In the light of the recent natural catastrophes and terrorist activities it has become evident that new architectural approaches are needed for the next generation Public Protection and Disaster Relief (PPDR) networks. These architectures should be adaptable to the conditions at the event site, resilient enough to operate under adverse conditions of the emergency. Furthermore, they should enable timely gathering of crucial event data and its delivery to the responder units at the site as well as the command and control centre that are off-site. In this paper, we first examine the state-of-the-art for areas related to communication in PPDR systems, and discuss the open research issues for each topic. Then, we propose a novel architecture that meets the aforementioned requirements which relies on a novel device called Intelligent Cognitive Gateway (ICG). ICG enables flexible use of the spectrum and facilitates data gathering from all lower tier devices and relays this data to the relevant units through the higher tier public or commercial backhaul networks. Finally, we provide some results that justify the need for these devices in emergency scenarios.
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    PublicationOpen Access
    Opportunistic reliability for cognitive radio sensor actor networks in smart grid
    (Elsevier, 2016) Biçen, Ozan; Ergül, Özgür; Akan, Özgür Barış; PhD Student; Faculty Member; College of Engineering
    Reliability is one of the most important requirements in Smart Grid communications. Reliable detection of an emergency event enables timely response. Within the automated nature of Smart Grid, such detection and response are carried out by sensor and actuator nodes. Therefore, it is important to study the capabilities of wireless sensor actor networks. In this paper, we first present an analysis of reliability in sensor actor networks, and lay out the factors that affect reliability. We then propose a scheme, where actor nodes cooperate to reach a global estimate under interruptions due to licensed user interference, i.e., consensus. We show that consensus improves reliability compared to local estimation of event features. We further show that convergence rate depends on connectivity of actors. Our analyses are generic and can be applied to inhomogeneous licensed user activity and interference on channels. A simulation study is presented to support our analyses and demonstrate the performance of proposed scheme in achieving consensus and mitigating disagreement among actor nodes.