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Publication Metadata only A correlation-based and spectrum-aware admission control mechanism for multimedia streaming in cognitive radio sensor networks(Wiley, 2017) Hosseini, Elahe S.; Esmaeelzadeh, Vahid; Berangi, Reza; Department of Electrical and Electronics Engineering; Akan, Özgür Barış; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; 6647Bandwidth management and traffic control are critical issues to guarantee the quality of service in cognitive radio networks. This paper exploits a network load refinement approach to achieve the efficient resource utilization and provide the required quality of service. A connection admission control approach is introduced in cognitive radio multimedia sensor networks to provide the data transmission reliability and decrease jitter and packet end-to-end delay. In this approach, the admission of multimedia flows is controlled based on multimedia sensors' correlation information and traffic characteristics. We propose a problem, connection admission control optimization problem, to optimize the connection admission control operation. Furthermore, using a proposed weighting scheme according to the correlation of flows issued by multimedia sensors enables us to convert the connection admission control optimization problem to a binary integer-programming problem. This problem is a kind of a Knapsack problem that is solved by a branch and bound method. Simulation results verify the proposed admission control method's effectiveness and demonstrate the benefits of admission control and traffic management in cognitive radio multimedia sensor networks.Publication Metadata only A novel orthogonal frequency division multiplexing with index modulation waveform with carrier frequency offset resistance and low peak-to-average power ratio(Wiley, 2022) Kucukyavuz, Defne; Onat, Furuzan Atay; N/A; Department of Electrical and Electronics Engineering; Gürol, İlter Erol; Başar, Ertuğrul; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 149116In this paper, we propose a novel orthogonal frequency division multiplexing (OFDM) scheme with high carrier frequency offset (CFO) resistance and low peak-to-average power ratio (PAPR). In this scheme, we consider a hybrid model with two subblock types, namely, pilot subblocks and standard subblocks. In pilot subblocks, active subcarriers are utilized for PAPR reduction while inactive carriers generated by the index modulation (IM) are utilized for the coarse CFO estimation. For standard subblocks, we consider unique subcarrier activation patterns (SAPs) with high-diversity IM to enhance the bit error performance of the overall system. Additionally, the inactive data tones in standard subblocks are utilized for fine CFO estimation, which enhances the CFO estimation quite significantly. Furthermore, in this paper, we show that proposed hybrid OFDM-IM (H-OFDM-IM) scheme can outperform conventional OFDM-IM and classical OFDM both in CFO estimation and PAPR reduction without requiring transmission of any side information. Finally, we show both mathematically and through computer simulations that proposed H-OFDM-IM can achieve a satisfactory bit error rate (BER) performance under high CFO scenarios.Publication Open Access An information theoretical analysis of nanoscale molecular gap junction communication channel between cardiomyocytes(Institute of Electrical and Electronics Engineers (IEEE), 2013) Kılınç, Deniz; Akan, Özgür Barış; College of EngineeringMolecular communication (MC) is a promising paradigm to communicate at nanoscale and it is inspired by nature. One of the MC methods in nature is the gap junction (GJ) communication between cardiomyocytes. The GJ communication is achieved by diffusion of ions through GJ channels between the cells. The transmission of the information is realized by means of the propagation of the action potential (AP) signal. The probabilities of both the AP propagation failure and the spontaneous AP initiation are obtained. For the first time in the literature, the GJ communication channel is modeled and analyzed from the information theoretical perspective to find the communication channel capacity. A closed-form expression is derived for the capacity of the GJ communication channel. The channel capacity, propagation delay, and information transmission rate are analyzed numerically for a three-cell network. The results of the numerical analyses point out a correlation between an increase in the incidence of several cardiac diseases and a decrease in the channel capacity, an increase in the propagation delay, and either an increase or a decrease in the transmission rate. The method that we use and results that are presented may help in the investigation, diagnosis, and treatment of cardiac diseases as well as help in the design of nanodevices communicating via GJ channels.Publication Open Access ARIMA based time variation model for beneath the chassis UWB channel(SpringerOpen, 2016) Department of Electrical and Electronics Engineering; Ergen, Sinem Çöleri; Demir, Utku; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; 7211; N/AIntra-vehicular wireless sensor network (ivwsn) enables the integration of the wireless sensor network technology into the vehicle architecture through either eliminating the wires between the existing sensors and the corresponding electronic controller units (ecus) or empowering new sensor technologies that are not currently implemented due to technical limitations. Ultra-wideband (uwb) has been determined to be the most appropriate technology for ivwsns since it provides energy efficiency through the low duty-cycle operation and high reliability by exploiting the large bandwidth. In this paper, we propose a time variation model for uwb-based ivwsn-based on the extensive amount of data collected from the transmitter and receiver antennas at various locations and separation distances beneath the chassis of a vehicle moving at different speeds on different types of roads. We adopt the commonly used saleh-valenzuela (sv) model to represent the clustering phenomenon in the received power delay profiles (pdps). The proposed novel time variation model then determines the time evolution of the pdps by representing the changes in their cluster breakpoints, slopes, and break point amplitudes with the auto-regressive integrated moving average (arima) model. Arima(5,1,0) has been demonstrated to fit the breakpoint, cluster slope, and breakpoint amplitude sequences collected at different vehicle speeds with different transmitter and receiver locations on asphalt and stone roads by using box-jenkins procedure. This model is validated with diagnostic checking. The absolute values of the model coefficients are observed to be mostly larger on asphalt road than their counterparts on the stone road while exhibiting no dependence on the vehicle speed nor the location of transmitter and receiver antennas.Publication Metadata only C-MRC-based cooperative spatial modulation with antenna selection(Wiley, 2020) Aydın, Erdoğan; İlhan, Hacı; Kabaoğlu, Nihat; Department of Electrical and Electronics Engineering; Başar, Ertuğrul; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; 149116A new high-performance low-complexity cooperative maximal ratio combining (C-MRC)-based cooperative relaying scheme, which is called antenna selection-aided cooperative spatial modulation scheme with C-MRC (AS-CSM), is proposed for decode and forward (DF)-based cooperative relaying networks operating over independent but non-identically distributed (i.n.d.) Rayleigh fading channels. The AS-CSM scheme is formed with the combination of cooperative SM with the high-performance low-complexity coherent demodulator C-MRC and antenna selection techniques. In the AS-CSM scheme, the information is transmitted from the source terminal (ST) to the relay terminal (RT) and the destination terminal (DT) in the form of not only modulated symbols but also antenna indices, which carry additional information bits in the spatial domain. Therefore, a high spectral efficiency is obtained by the proposed scheme for cooperative relaying networks. In this scheme, first, the index of the activated antenna of ST is estimated, and the best antenna selection at RT is investigated considering the received instantaneous equivalent to signal-to-noise values acquired at DT. The transmitted symbols are estimated with low-complexity coherent demodulator C-MRC at DT by using the noisy signals from ST and RT. An exact closed-form expression for the bit error probability (BEP) of the AS-CSM scheme is derived, and the theoretical results are validated with Monte-Carlo simulation results.Publication Open Access Communicate to illuminate: state-of-the-art and research challenges for visible light communications(Elsevier, 2015) Ergül, Özgür; Dinç, Ergin; Akan, Özgür Barış; PhD Student; PhD Student; College of EngineeringIn the near future, the available radio-frequency (RF) bandwidth will not be sufficient to meet the ever increasing demand for wireless access. Visible light communication (VLC) is an alternative method to reduce the burden of RF-based communication, especially in indoor communications. 70% of the communication is indoors, and light emitting diode (LED) arrays are spreading for illumination purposes thanks to their low energy and higher lifetime. VLC can be realized as a secondary application in LED arrays that are placed for lighting. In this way, some of the wireless traffic can be sent using light, with less cost and less carbon footprint. For these reasons, VLC attracts significant research interests. We provide an extensive survey of the current literature by outlining challenges and future research areas in order to facilitate future research in this area.Publication Metadata only Duty-cycle optimization for IEEE 802.15.4 wireless sensor networks(Assoc Computing Machinery, 2013) Park, Pangun; Fischione, Carlo; Sangiovanni-Vincentelli, Alberto; Department of Electrical and Electronics Engineering; Ergen, Sinem Çöleri; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; 7211Most applications of wireless sensor networks require reliable and timely data communication with maximum possible network lifetime under low traffic regime. These requirements are very critical especially for the stability of wireless sensor and actuator networks. Designing a protocol that satisfies these requirements in a network consisting of sensor nodes with traffic pattern and location varying over time and space is a challenging task. We propose an adaptive optimal duty-cycle algorithm running on top of the IEEE 802.15.4 medium access control to minimize power consumption while meeting the reliability and delay requirements. Such a problem is complicated because simple and accurate models of the effects of the duty cycle on reliability, delay, and power consumption are not available. Moreover, the scarce computational resources of the devices and the lack of prior information about the topology make it impossible to compute the optimal parameters of the protocols. Based on an experimental implementation, we propose simple experimental models to expose the dependency of reliability, delay, and power consumption on the duty cycle at the node and validate it through extensive experiments. The coefficients of the experimental-based models can be easily computed on existing IEEE 802.15.4 hardware platforms by introducing a learning phase without any explicit information about data traffic, network topology, and medium access control parameters. The experimental-based model is then used to derive a distributed adaptive algorithm for minimizing the power consumption while meeting the reliability and delay requirements in the packet transmission. The algorithm is easily implementable on top of the IEEE 802.15.4 medium access control without any modifications of the protocol. An experimental implementation of the distributed adaptive algorithm on a test bed with off-the-shelf wireless sensor devices is presented. The experimental performance of the algorithms is compared to the existing solutions from the literature. The experimental results show that the experimental-based model is accurate and that the proposed adaptive algorithm attains the optimal value of the duty cycle, maximizing the lifetime of the network while meeting the reliability and delay constraints under both stationary and transient conditions. Specifically, even if the number of devices and their traffic configuration change sharply, the proposed adaptive algorithm allows the network to operate close to its optimal value. Furthermore, for Poisson arrivals, the duty-cycle protocol is modeled as a finite capacity queuing system in a star network. This simple analytical model provides insights into the performance metrics, including the reliability, average delay, and average power consumption of the duty-cycle protocol.Publication Metadata only Editorial on special issue "radio access technologies for beyond 5G wireless networks''(Elsevier, 2020) Arslan, Hüseyin; Xiao, Yue; Department of Electrical and Electronics Engineering; Başar, Ertuğrul; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; 149116Publication Metadata only Effective capacity and outage probability assessment of multiple-relay cognitive communication systems in Nakagami-m and Rayleigh fading channel(Wiley, 2020) Zahedi, Abdulhamid; Shayea, Ibraheem; El-Saleh, Ayman A.; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Ergen, Onur; Ergen, Mustafa; Researcher; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; College of Engineering; N/A; N/AThe radio spectrum of communication systems is largely occupied by wideband technologies, and thus, efficient usage of spectrum is a crucial requirement from regulators' and service providers' perspectives. Cognitive communication has been proposed as a potential solution to resolve the spectrum scarcity problem. Cognitive radio schemes can be jointly applied with cooperative communications to improve the performance under both overlay and underlay strategies as the two main cognitive strategies supported by multiple relays. This combination significantly improves the reliability and capacity of data communication. In this paper, two QoS parameters, namely, the effective capacity and outage probability, have been thoroughly analyzed in a Nakagami-m fading channel that is the typical channel condition often considered in the transmission of communication systems. Closed-form expressions are obtained for effective capacity and outage probability in both underlay and overlay strategies. Simulation results verify the effectiveness of the mathematical modelling of the proposed QoS parameters.Publication Metadata only Information-centric networking for multimedia, social and peer-to-peer communications(Wiley, 2014) Anadiotis, Angelos-Christos G.; Patrikakis, Charalampos Z.; Department of Electrical and Electronics Engineering; Tekalp, Ahmet Murat; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; 26207Information-centric networking (ICN) is an emerging networking paradigm, which is considered as a possible solution for the next generation Internet. Several research projects have been funded by the state and the industry towards the specification and implementation of ICN solutions, whereas Internet Research Task Force has established a research group for this reason, the Information-Centric Networking Research Group. However, the use of ICN in action will be decided on the basis of its performance in several disciplines that, eventually, concern the users expectations from their applications over the future Internet. Currently, statistics suggest that, in the near future, the Internet bandwidth will be mainly consumed by multimedia and peer-to-peer applications. Furthermore, social networking applications become more and more popular both to end-users and businesses. This special issue includes papers illustrating how information-centric networks can effectively address practical issues rising in ICN deployments considering multimedia applications and social networking technologies.