Researcher: Akan, Özgür Barış
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Akan, Özgür Barış
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Publication Metadata only A physical channel model for nanoscale neuro-spike communications(IEEE-Inst Electrical Electronics Engineers Inc, 2013) Balevi, eren; Department of Electrical and Electronics Engineering; Akan, Özgür Barış; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; 6647Nanoscale communications is an appealing domain in nanotechnology. Novel nanoscale communications techniques are currently being devised inspired by some naturally existing phenomena such as the molecular communications governing cellular signaling mechanisms. Among these, neuro-spike communications, which governs the communications between neurons, is a vastly unexplored area. The ultimate goal of this paper is to accurately investigate nanoscale neuro-spike communications characteristics through the development of a realistic physical channel model between two neurons. The neuro-spike communications channel is analyzed based on the probability of error and delay in spike detection at the output. The derived communication theoretical channel model may help designing novel artificial nanoscale communications methods for the realization of future practical nanonetworks, which are the interconnections of nanomachines.Publication Metadata only Electric-field energy harvesting in wireless networks(Ieee-Inst Electrical Electronics Engineers Inc, 2017) Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Çetinkaya, Oktay; Akan, Özgür Barış; Other; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; College of Engineering; N/A; 6647Electric-field energy harvesting (EFEH) can be considered as an emerging and promising alternative for self-sustainable next-generation WSNs. Unlike conventional harvesting methods that rely on ambient variables, EFEH provides more reliable and durable operation as it is operable with any voltage-applied conductive material. Therefore, it is better suited for advanced throughput and applications requiring a certain QoS. In this article, we introduce this newly emerging WSN paradigm, and focus on enabling EFEH technology for smart grid architectures, such as home, building, and near area networks, where the field intensity is relatively low. To this end, a practical methodology and a general use implementation framework have been developed for low-voltage applications by regarding compelling design issues and challenging source scarcity. The proposed double-layer harvester model is experimentally evaluated. Its performance in terms of implementation flexibility, sensor lifetime, and communication throughput is investigated. In addition, current challenges, open issues, and future research directions are discussed for the design of more enhanced EFEH wireless networks.Publication Metadata only Energy-efficient packet size optimization for cognitive radio sensor networks(Ieee-Inst Electrical Electronics Engineers Inc, 2012) N/A; N/A; Department of Electrical and Electronics Engineering; Oto, Mert Can; Akan, Özgür Barış; Researcher; Faculty Member; Department of Electrical and Electronics Engineering; N/A; College of Engineering; N/A; 6647Cognitive Radio (CR) and its dynamic spectrum access capabilities can be exploited by many wireless network architectures including sensor networks. Thus, cognitive radio sensor networks (CRSN) has emerged as a promising solution to address the spectrum-related challenges of wireless sensor networks (WSN). Among others, determination of the optimal packet size is one of the most fundamental problems to be addressed for the practical realization of CRSN. The existing optimal packet size solutions devised for wireless, sensor, and CR networks are not applicable in CRSN regime. Hence, the objective of this paper is to determine the optimal packet size for CRSN that maximizes energy-efficiency while maintaining acceptable interference level for licensed primary users (PU) and achieving reliable event detection at the sink. The energy-efficient optimal packet size is analytically formulated and its variation with respect to different network parameters is observed. Results reveal that PU behavior and channel BER are the most critical parameters in determining the energy-efficient optimal packet size for CRSN.Publication Metadata only FRET-based nanoscale point-to-point and broadcast communications with multi-exciton transmission and channel routing(Ieee-Inst Electrical Electronics Engineers Inc, 2014) N/A; N/A; Department of Electrical and Electronics Engineering; Kuşcu, Murat; Akan, Özgür Barış; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; 316349; 6647Nanoscale communication based on Forster Resonance Energy Transfer (FRET) enables nanoscale single molecular devices to communicate with each other utilizing excitons generated on fluorescentmolecules as information carriers. Based on the point-to-point single-exciton FRET-based nanocommunication model, we investigate the multiple-exciton case for point-to-point and broadcast communications following an information theoretical approach and conducting simulations through Monte Carlo approach. We demonstrate that the multi-exciton transmission significantly improves the channel reliability and the range of the communication up to tens of nanometers for immobile nanonodes providing high data transmission rates. Furthermore, our analyses indicate that multi-exciton transmission enables broadcasting of information from a transmitter nanonode to many receiver nanonodes pointing out the potential of FRET-based communication to extend over nanonetworks. In this study, we also propose electrically and chemically controllable routing mechanisms exploiting the strong dependence of FRET rate on spectral and spatial characteristics of fluorescent molecules. We show that the proposed routing mechanisms enable the remote control of information flow in FRET-based nanonetworks. The high transmission rates obtained by multi-exciton scheme for point-to-point and broadcast communications, as well as the routing opportunities make FRET-based communication promising for future molecular computers.Publication Metadata only Cognitive radio sensor networks in industrial applications(CRC Press, 2017) N/A; Department of Electrical and Electronics Engineering; Biçen, Ahmet Ozan; Akan, Özgür Barış; Master Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 6647This chapter explains the benefits of cognitive radio sensor networks (CRSN) in industrial applications and discusses the open research directions for this promising research area. It also discusses the CRSN architecture configurations in industrial applications. The chapter presents the algorithm needs of CRSN for spectrum management in industrial applications. It provides the open research issues on communication protocol development for CRSN in industrial applications. Minimization of environmental effects, adaptation to varying spectrum conditions, and overlay deployment of multiple sensor networks are some of the promising advantages of CRSN in industrial applications. However, the realization of CRSN in industrial applications mainly requires efficient spectrum management functionalities to dynamically manage the spectrum access of sensor nodes in challenging industrial communication environments. Requirements and research challenges for main three spectrum management functionalities of cognitive radio, that is, spectrum sensing, spectrum decision, and spectrum mobility, are explored below for CRSN from the perspective of industrial applications.Publication Metadata only Vehicular social sensor networks(CRC Press, 2017) N/A; N/A; Department of Electrical and Electronics Engineering; Çepni, Kardelen; Özger, Mustafa; 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; N/A; 6647N/APublication Metadata only Information theoretical optimization gains in energy adaptive data gathering and relaying in cognitive radio sensor networks(IEEE-Inst Electrical Electronics Engineers Inc, 2012) N/A; Department of Electrical and Electronics Engineering; Gülbahar, Burhan; Akan, Özgür Barış; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; 234525; 6647Cognitive radio (CR) technology helps mitigate wireless resource scarcity problem by dynamically changing frequency spectrum, power and modulation type. Opportunistic spectrum access increases the network capability and quality. Recently, CR applied to wireless sensor networks (WSNs) generated the paradigm of cognitive radio sensor networks (CRSNs) overcoming the challenges posed by event-driven traffic demands of WSNs. To realize advantages of CRSN, spectrum and power allocation, and routing must be jointly considered to maximize the information capacity, resource utilization and the lifetime. In this paper, power and rate adaptation problem is analyzed for a multi-hop CRSN in an information theoretical (IT) capacity maximization framework combined with energy adaptive (EA) mechanisms and utilization of sensor data information correlations (ICs). CRSN characteristics, i.e., fast data aggregation, bursty traffic and node failures, are considered. The capacity optimization problem is defined analytically and practical local schemes are presented showing the superiority of objective functions utilizing ICs and EA mechanisms in terms of the resulting maximum information rate at sink, i.e., R-max, lifetime, and energy utilization. Furthermore, dependence of performance on total bandwidth and various relay energy distributions is explored observing the logarithmic dependence of R-max on total bandwidth.Publication Metadata only Maximization of energy-efficiency under convergence constraint in wireless networked control systems(Ieee, 2015) N/A; N/A; Department of Electrical and Electronics Engineering; Özger, Mustafa; Akan, Özgür Barış; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 6647Wireless networked control system (WNCS) is a control system that a wireless network closes the control loop. WNCS estimator, i. e., Kalman filter, estimates the system state according to the observations of sensors. These observations which are from N independent subnetworks are conveyed to the Kalman filter through vacant bands opportunistically with cognitive radio capability of the nodes. We characterize the successful packet delivery probability and study the maximization of energy-efficiency of overall system under the convergence constraint of the Kalman filter by defining an optimization problem. We also find a lower bound on maximum total coverage area. Furthermore, we perform numerical analysis to observe the effects of system parameters such as number of subnetworks, average ON probability of primary users, transmission ranges and densities of sensor nodes and primary users, and false alarm probability.Publication Metadata only Energy-efficient RF source power control for opportunistic distributed sensing in wireless passive sensor networks(IEEE, 2012) N/A; Department of Electrical and Electronics Engineering; Biçen, Ahmet Ozan; Akan, Özgür Barış; Master Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 6647Energy limitation of sensor nodes is the main constraint to be addressed while designing and implementing algorithms for wireless sensor networks (WSN). Recently, to mitigate battery depletion problem and extend network lifetime, wireless passive sensor networks (WPSN) have become a new field of interest. Modulated backscattering is an important communication technique for WPSN to enable unlimited lifetime for sensor nodes. Determination of required number and power level of RF sources for wireless power transfer to sensor nodes is crucial for energy-efficient distributed sensing operation. Furthermore, deployed RF sources can share spectrum opportunistically via incorporation of cognitive radio capability such that desired distributed estimation distortion can be achieved with minimum spectrum utilization by WPSN. Employment of RF sources that radiate power only when spectrum opportunities are available unveils passive opportunistic distributed sensing (PODS). in this paper, first, we model intercepted power by passive sensor from RF sources and reflected power by passive sensor at the sink, and effect of opportunistic access to licensed spectrum bands on instantaneous throughput of sensor nodes. then, A power level control scheme for RF sources is proposed to achieve desired distortion level with minimum energy consumption while using opportunistic distributed sensing in WPSN. achieved estimation distortion at sink with respect to number and power level of RF sources, and available spectrum opportunities is investigated, and energy saving provided by proposed power control scheme is assessed for various distortion requirements, channel noise levels, and available spectrum opportunities via simulation experiments.Publication Metadata only Fret-based mobile molecular nanonetworks(Ieee, 2013) N/A; N/A; Department of Electrical and Electronics Engineering; Kuşcu, Murat; Akan, Özgür Barış; Master Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; 316349; 6647Nanonetworks refer to a group of nano-sized machines with very basic operational capabilities communicating to each other in order to accomplish more complex tasks such as in-body drug delivery, or chemical defense. Realizing reliable and high-rate communication between these nanomachines is a fundamental problem for the practicality of these nanonetworks. Recently, we have proposed a molecular communication method based on Forster resonance energy transfer (FRET) which is a nonradiative excited state energy transfer phenomenon observed among fluorescent molecules, i.e., fluorophores. We have modeled the FRET-based communication channel considering the fluorophores as single-molecular immobile nanomachines, and shown its reliability at high rates, and practicality at the current stage of nanotechnology. In this study, we focus on network of mobile nanomachines communicating through FRET. We introduce two novel mobile molecular nanonetworks: FRET-based mobile molecular sensor/actor nanonetwork (FRET-MSAN) which is a distributed system of mobile fluorophores acting as sensor or actor node; and FRET-based mobile ad hoc molecular nanonetwork (FRET-MAMNET) which consists of fluorophore-based nanotransmitter, nanoreceivers and nanorelays. We model the single message propagation exploiting the SIR model of epidemics. We derive closed form expressions for the probability of the actor nodes to detect a message generated on the sensor nodes in FRET-MSAN, and for the average detection time of the transmitted message by the nanoreceivers in FRET-MAMNET. We numerically evaluate the performance of these networks in terms of reliability and transmission delay for varying number of nanonodes and varying size of nanomachines, as well as, for several FRET-related parameters.