Browsing by Author "Baykaş, Tunçer"

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Citation Count: 1
A 130 nm CMOS Receiver for Visible Light Communication
(IEEE-Inst Electrical Electronics Engineers Inc, 2022) Baykaş, Tunçer; Yagan, Muhammed Yaser; Uysal, Murat; Pusane, Ali Emre; Baykas, Tuncer; Dundar, Gunhan; Yalcinkaya, Arda Deniz
Visible light communication (VLC) is an emerging technology that has been gaining attention over the last few years. Transmission of data at higher rates in a VLC system is mainly limited by the modulation bandwidth of the employed LED. To alleviate this limitation, equalization is frequently employed. This is usually achieved by either using discrete circuit elements or in digital form. In this paper, we present a power-efficient VLC receiver as a system-on-chip, implemented in 130 nm CMOS technology. The proposed receiver supports LEDs with different bandwidths thanks to the switchable equalizer. We tested the proposed receiver using phosphorescent white LEDs with different bandwidths on an experimental VLC link. For each tested LED, around 20 fold improvement in data rate was achieved compared to the original bandwidth of the LED. For the LED with a modulation bandwidth of 1.6 MHz, data rates of 32 Mbps and 50 Mbps at a BER of 10(-2) were obtained at a distance of 2 meters without and with a blue filter, respectively.
Citation Count: 0
Analysis and Optimization of the Network Throughput in IEEE 802.15.13 based Visible Light Communication Networks
(IEEE, 2021) Baykaş, Tunçer; Elamassie, Mohammed; Baykas, Tuncer; Uysal, Murat
In line with the growing interest on visible light communication (VLC), IEEE has initiated standardization efforts on this emerging technology. In this work, we consider IEEE 802.15.13 Optical Wireless Personal Area Networks (OWPAN) standard draft. The underlying MAC protocol uses contention free and contention access periods. For a standard-compliant VLC network, we analyze the network load and propose an algorithm to improve the network throughput by proper selection of period lengths. Our suggested algorithm improves the network performance by at least 5% in the case of variable network traffic up to 15 active users.
Citation Count: 1
Analysis of deep learning based path loss prediction from satellite images
(IEEE, 2021) Baykaş, Tunçer; Ates, Hasan F.; Baykas, Tuncer; Gunturk, Bahadir K.
Determining the channel model parameters of a wireless communication system, either by measurements or by running electromagnetic propagation simulations, is a time-consuming process. Any rapid deployment of network demands faster determination of at least major channel parameters. In this paper, we investigate the idea of using deep convolutional neural networks and satellite images for channel parameters (i.e., path loss exponent n and shadowing factor sigma) prediction in a cellular network with aerial base stations. Specifically, we investigate the performance dependency of the method on three different factors: height of the transmitter antenna, quantization levels of the channel parameters and architectural design of CNN. The results presented in this paper show a high prediction accuracy of the channel parameters in real-time.
Citation Count: 4
Analysis of Extended Busy Tone Performance for Coexistence between WRAN and WLAN TVWS Networks
(IEEE, 2015) Baykaş, Tunçer; Erküçük, Serhat; Baykaş, Tunçer
TV White Spaces indicate spectrum bands which were reserved for licensed terrestrial TV broadcasting and opened to unlicensed use under regulatory conditions. One important regulation which is common in all regulatory domains is no harmful interference is created to licensed devices. On the other hand interference between unlicensed devices is not regulated. As a result system designers developed new methods to improve coexistence between TVWS networks. Extended busy tone one of such methods is designed for coexistence between wireless regional area and wireless local area networks based on IEEE 802.22 and 802.11af standards respectively. In this paper we analyse the performance of extended busy tone at different range conditions and verify via simulations under realistic conditions. Our results indicate that the method can reduce interference considerably at intermediate distances and enable networks to operate without a significant reduction in throughput.
Citation Count: 0
Biyomimetik Ve Kablosuz Motor Nöroprotez Tasarımı
(2019) Kocatürk, Mehmet; Canbeyli, Reşit Şahin; Baykaş, Tunçer; Güveniş, Albert; Gülçür, Halil Özcan
Motor nöroprotezler beyin dokusu ile doğrudan iletişim kurarak bir hastalık ve yaralanma sonucu meydana gelen motor fonksiyon kayıplarını telafi etmeyi amaçlar. Motor nöroprotez teknolojisindeki umut verici gelişmelere rağmen günümüze kadar geliştirilmiş sistemlerin halen motor korteks nöronlarının değişen etkinlik desenlerine uyum sağlama sorunu vardır. Bu projede değişen sinirsel etkinlik desenlerine sadece bir dışsal ödül işaretiyle uyum sağlayabilen ve motor korteks ile striatum arasındaki etkileşimleri taklit ederek çalışan bir biyomimetik motor nöroprotez şifre çözücüsünün üzerinde çalışılmıştır. Gerçek-zamanlı simülasyonlarla bahsi geçen şifre çözücünün sorunsuz çalışması için sıçan motor korteksinden en az 15-18 nörondan sinirsel etkinlik kaydı alınması gerektiği ortaya çıkarılmıştır. Biyomimetik şifre çözücüsüne gerekli sinirsel işaret girdilerini sağlamak için 16 ve 32 kanallı mikroelektrot dizilerinin üretim ve kronik implantasyon yöntemleri geliştirilmiştir. Biyomimetik şifre çözücüsünün in vivo sıçan deneyleriyle başarımının değerlendirilebilmesi için yeni bir davranışsal paradigma geliştirilmiştir. Davranışsal paradigmayı kullanarak 3 sıçanla nöroprotez kontrol denemeleri gerçekleştirilmiştir. Bütün denekler bir robot kolun tek ekseni etrafındaki hareketini kontrol etmeyi sinirsel edimsel koşullama aracılığıyla öğrenebilmiştir. Projede 16 kanallı mikroelektrot dizisinden alınan sinirsel işaretlerin kablosuz iletimi için düşük maliyetli bir prototip geliştirilmiştir. Projede geliştirilen mikroelektrot dizisi üretim ve implantasyon yöntemlerini, nöroprotez kontrolüne yönelik davranış paradigmasını ve kablosuz veri iletim yöntemlerini kullanarak sadece bu projede üzerinde çalışılan biyomimetik şifre çözücüsüne değil farklı başka yaklaşımlarla geliştirilmiş şifre çözücülerine de sinirsel işaret girdisi sağlamak mümkündür.
Citation Count: 3
Busy tone based coexistence algorithm for WRAN and WLAN systems in TV white space
(Inst Engineering Technology-IET, 2018) Baykaş, Tunçer; Erküçük, Serhat; Baykaş, Tunçer
TV White Space (TVWS) refers to frequency band reserved only for licensed terrestrial TV broadcasting and is opened to unlicensed use under regulatory conditions. While regulations protect licensed systems from interference interference among unlicensed systems is left mainly to manufacturers. Consequently there is a need to develop new coexistence approaches between TVWS networks. Busy tone broadcasting is a coexistence method which can be used by TVWS networks to announce the selected frequency band is occupied. In this paper a busy tone based coexistence algorithm is proposed for IEEE 802.11af and IEEE 802.22 networks and analyzed by considering different client distributions experiencing log-normal shadowing where the exact interfering packet rate and successful packet transmission rate expressions are obtained and validated by simulations for different scenarios. The results show that with the proposed coexistence approach a WLAN can reliably detect the busy tone signal to change its frequency band and can reduce interference to WRAN. Even if there is no available frequency band for the WLAN the WRAN still maintains its enhanced successful packet transmission performance. The deployment of the proposed algorithm is important for successful coexistence between cognitive wireless networks where interference is not regulated such as in TVWS bands.
Citation Count: 1
Busy tone based power control for coordination of IEEE 802.11af and 802.22 system [IEEE 802.11af ve 802.22 Sistemlerinin Uyumlu Çalışmaları için Meşgul Ton Tabanlı Güç Kontrolü]
(Institute of Electrical and Electronics Engineers Inc., 2017) Baykaş, Tunçer; Erküçük, Serhat; Karatalay, Onur; Baykaş, Tunçer
In this paper a new power control algorithm based on busy tone approach has been proposed for the coordination of IEEE 802.22 and IEEE 802.11af systems in TV white space. Different from the earlier studies in addition to both 802.11af access point and clients listening to the busy tone they also adjust their communication power according to the location information and use hopping for communication if needed. Acccordingly interference caused to 802.22 systems has been reduced while the 802.11af systems are still able to communicate. This study quantifies the 802.11af and 802.22 system performances in terms of interfering packet rate and succesful packet transmission rate for different scenarios considering the communication parameters and channel models adapted for the standards. © 2017 IEEE.
Citation Count: 1
Busy Tone Based Power Control for Coordination of IFFY 802.11af and 802.22 System
(IEEE, 2017) Baykaş, Tunçer; Erküçük, Serhat; Karatalay, Onur; Baykas, Tuncer
In this paper, a new power control algorithm based on busy tone approach has been proposed for the coordination of IEEE 802.22 and IEEE 802.11af systems in TV white space. Different from the earlier studies, in addition to both 802.11af access point and clients listening to the busy tone, they also adjust their communication power according to the location information and use hopping for communication, if needed Acccordingly, interference caused to 802.22 systems has been reduced while the 802.11af systems are still able to communicate. This study quantifies the 802.11af and 802.22 system performances in terms of interfering packet rate and succesful packet transmission rate for different scenarios considering the communication parameters and channel models adapted for the standards.
Citation Count: 1
Busy Tone Implementation for Coexistence of IEEE 802.22 and 802.11 af Systems
(IEEE, 2015) Baykaş, Tunçer; Erküçük, Serhat; Baykaş, Tunçer
In this paper a new algorithm based on busy tone approach has been proposed for the coexistence of IEEE 802.22 and IEEE 802.11af systems in TV white space. Different from the earlier study in addition to 802.11af access points listening to the busy tone signal their clients also listen to the busy tone and let the access points know once they hear it. Accordingly interference caused to 802.22 systems has been reduced. This study quantifies the improved system performance in terms of interfering packet rate for different hearing regions considering the communication parameters and channel models adapted for the standards.
Citation Count: 2
Busy tone implementation for coexistence of IEEE 802.22 and 802.11af systems
(Institute of Electrical and Electronics Engineers Inc., 2015) Baykaş, Tunçer; Erküçük, S.; Baykaş, T.
In this paper, a new algorithm based on busy tone approach has been proposed for the coexistence of IEEE 802.22 and IEEE 802.11af systems in TV white space. Different from the earlier study, in addition to 802.11af access points listening to the busy tone signal, their clients also listen to the busy tone and let the access points know once they hear it. Accordingly, interference caused to 802.22 systems has been reduced. This study quantifies the improved system performance in terms of interfering packet rate for different hearing regions considering the communication parameters and channel models adapted for the standards. © 2015 IEEE.
Citation Count: 0
Comparative Performance Evaluation of VLC, LTE and WLAN Technologies in Indoor Environments
(IEEE, 2021) Baykaş, Tunçer; Karbalayghareh, Mehdi; Miramirkhani, Farshad; Uysal, Murat; Baykas, Tuncer
Recent years have seen an exponential rise in the demand for indoor wireless connections that have driven future generation networks to aim for higher data rates with extended coverage and affordable rates. The two most prominent technologies for providing indoor wireless connections, WLAN and LTE, have their limitations and they can not coexist in a single band to form heterogeneous networks (HetNets). Visible light communication (VLC) has seen rapid growth in recent years as it has the capability to seamlessly merge with the existing technologies and provide wireless connections with high data rates. VLC based hybrid indoor network effectively combines the preferences of an end-user with the practicality of implementation. In this work, we investigate specific VLC/WLAN and VLC/LTE hybrid scenarios to perform a detailed analysis on the effect of user mobility on the performance of the system and how the performance of the network (in terms of throughput) can be maximized The study aims to show how different technologies complement each other in the best and even the worst-case scenarios.
Citation Count: 0
Gelecek Nesil İletişim Sistemleri Için Zaman-Frekans Yayılımlı Seyrek Kodlu Çoklu Erişim
(2023) Baykaş, Tunçer; Ülgen, Oğuz; Tüfekçi, Tolga Kağan; Anpalagan, Subramanıam Alagan; Şadi, Yalçın
Gelecek Nesil İletişim Sistemleri için Zaman-Frekans Yayılımlı Seyrek Kodlu Çoklu Erişim adlı proje, 1001 Araştırma Programı kapsamında 2021-2023 yılları arasında TÜBİTAK tarafından desteklenmiştir. Bu projenin amacı, 4G için önerilen dikgen frekans ve kod bölmeli çoğullama yönteminin hem zaman hem de frekans yayılımlarının getirdiği kazançlar dikkate alınarak, SCMA tabanlı yeni çoklu erişim yöntemleri geliştirmektir. Buna göre SCMA yönteminin kodlama kazancına ek olarak zaman ve frekans yayılımlarının katılması ile hem aşağı bağlantı hem de yukarı bağlantıda daha iyi çoklu erişim performansları elde edilmesi hedeflenmiştir. Bu yeni yöntem Zaman-Frekans Yayılımlı SCMA (SCMA with Time-Frequency Spreading ? SCMA-TFS) olarak adlandırılmıştır. Bu doğrultuda yapılan çalışmalar şu şekilde özetlenebilir. Zaman yayılımı ve tekrarlamalı gönderimlerin SCMA modeline dahil edilmesiyle veri hızı ve çoklu erişim performansı analiz edilmiş, önerilen sistemin veri hızını düşürmeden BER performansını artırdığı gösterilmiştir. Bu başarım gösterilirken önerilen sistemin hesaplama karmaşıklığının sınırlı olarak arttığı ve dolayısıyla pratikliği gösterilmiştir. Önerilen SCMA-TFS sisteminin başarımını maksimize etmek için gerekli optimal kod kitabı tasarımına dönük olarak genetik algoritma tabanlı kod kitabı tasarımları yapılmış, önerilen kod kitaplarının literatürdeki kod kitaplarına belirli kanallardaki üstünlüğü gösterilmiştir. Son olarak PN dizisi seçiminin SCMA-TFS sisteminin BER performansını artırarak ISI probleminin çözümüne önemli katkı sağladığı gösterilmiştir.
Citation Count: 0
Hybrid MEMS-Based molecular communication system
(Institute of Electrical and Electronics Engineers Inc., 2019) Baykaş, Tunçer; Erküçük, Serhat; Zeshan, Arooba; Pusane, Ali Emre
In this paper, we consider a molecular communication link integrated in a micro-electro mechanical system (MEMS) based environment. We apply acoustic tweezing techniques to the molecular communication system to increase communication reliability. We use finite element methods to simulate this hybrid system. By deriving the symbol error rate as the performance metric, we show that the proposed system facilitates reliable communication in the presence of fluid flow and its performance is robust against external factors, such as temperature.
Citation Count: 0
IEEE 802.11BB Reference Channel Models For Light Communications
(Institute of Electrical and Electronics Engineers Inc., 2023) Baykaş, Tunçer; Baykas,T.; Elamassie,M.; Uysal,M.
Increasing industrial attention to visible light communications (VLC) technology led the IEEE 802.11 to establish the task group 802.11bb 'Light Communications' (LC) for the development of a VLC standard. As a part of the standard development process, the development of realistic channel models according to possible use cases is of critical importance for physical layer system design. This article presents the reference channel models for the mandatory usage models adopted by IEEE 802.11bb for the evaluation of system proposals. The use cases include industrial, medical, enterprise, and residential scenarios. Channel impulse responses and corresponding frequency responses are obtained for each use case using a ray tracing approach based on realistic specifications for transmitters and receivers, and optical characterization of the environment. © 2023 IEEE.
Citation Count: 112
IEEE 802.15.7r1 Reference Channel Models for Visible Light Communications
(IEEE-Inst Electrical Electronics Engineers Inc, 2017) Baykaş, Tunçer; Narmanlıoğlu, Ömer; Baykas, Tuncer; Uysal, Murat; Panayırcı, Erdal
The IEEE has established the standardization group 802.15.7r1 "Short Range Optical Wireless Communications", which is currently in the process of developing a standard for visible light communication (VLC). As with any other communication system, realistic channel models are of critical importance for VLC system design, performance evaluation, and testing. This article presents the reference channel models that were endorsed by the IEEE 802.15.7r1 Task Group for evaluation of VLC system proposals. These were developed for typical indoor environments, including home, office, and manufacturing cells. While highlighting the channel models, we further discuss physical layer techniques potentially considered for IEEE 802.15.7r1.
Citation Count: 0
An Integrated Molecular Communication System Based on Acoustic Tweezers
(IEEE-Inst Electrical Electronics Engineers Inc, 2023) Baykaş, Tunçer; Pusane, Ali Emre; Baykas, Tuncer
In this work, a molecular communication link integrated with a micro-electro mechanical system (MEMS) based environment has been designed and simulated. The motivation behind this approach is to explore the possibility of merging acoustic tweezing technique with a molecular communication system to increase the accuracy and reliability of the overall communication link. The proposed design is simulated using finite element methods that mimic the actual environment for an accurate solution. We derive symbol error rate as a performance metric and further show that the proposed system outperforms the diffusion-based modulation techniques and facilitates a reliable communication in the presence of fluid flow and while being insusceptible to external factors.
Citation Count: 8
Location Aware Vertical Handover in a VLC/WLAN Hybrid Network
(IEEE-Inst Electrical Electronics Engineers Inc, 2021) Baykaş, Tunçer; Baykas, Tuncer
Visible light communication (VLC) has emerged as a promising technology for wireless communication as it offers higher data rates and secure data transmission along with providing indoor illumination. However, VLC is restricted by the line of sight (LoS) nature of the optical channel that consequently results in light path blockages. Therefore, an effective solution would be to combine VLC with a radio frequency (RF) system to form a hybrid VLC/RF network that would take into account the preferences of an end-user with the practicality of implementation. In such networks, an efficient vertical handover (VHO) technique is the most critical element as it ensures a seamless transition between the two networks. In this work, we propose a vertical handover technique that utilizes the user's location information to make a handover decision. We found that the frequency of light path blockages increases with the increasing number of users in a confined space, resulting in significant performance deterioration. This additional information is then utilized so that the VHO algorithm effectively selects the most feasible network. The proposed algorithm has been tested against the immediate vertical handover algorithm (I-VHO) and the dwell vertical handover algorithm (D-VHO) with two different dwell times. The average number of handovers, quality of experience (QoE), and packet loss have been set as performance metrics. We show from several simulation scenarios that the proposed method results in a fewer number of handovers while maintaining higher QoE and lower packet loss.
Citation Count: 6
Measurement-Based Large Scale Statistical Modeling of Air-to-Air Wireless UAV Channels via Novel Time-Frequency Analysis
(IEEE-Inst Electrical Electronics Engineers Inc, 2022) Baykaş, Tunçer; Kaplan, Batuhan; Kahraman, Ibrahim; Kesir, Samed; Yarkan, Serhan; Ekti, Ali Riza; Baykas, Tuncer
Any operation scenario for unmanned aerial vehicles also known as drones in real world requires resilient wireless link to guarantee capacity and performance for users, which can only be achieved by obtaining detailed knowledge about the propagation channel. Thus, this study investigates the large-scale channel propagation statistics for the line of sight air-to-air (A2A) drone communications to estimate the path loss exponent (PLE). We conducted a measurement campaign at 5.8 GHz, using low cost and light weight software defined radio based channel sounder which is developed in this study and then further integrated on commercially available drones. To determine the PLE, frequency-based, time-based and time-frequency based methods are utilized. Accuracy of the proposed method is verified under ideal conditions in a well-isolated anechoic chamber before the actual measurement campaign to verify the performance in a free space path loss environment. The path loss exponent for A2A wireless drone channel is estimated with these verified methods.
Citation Count: 1
A new approach for coexistence of IEEE 802.11af and IEEE 802.22 systems
(Institute of Electrical and Electronics Engineers Inc., 2018) Baykaş, Tunçer; Erküçük, Serhat; Erküçük, Serhat
In this paper various algorithms are proposed to help IEEE 802.11af and IEEE 802.22 wireless systems to coexist in TV white space by considering multiple techniques. By using busy tone power control and multihop communication techniques improvements have been made compared to prior approaches. With this approach while IEEE 802.22 systems are protected from intra-network interference IEEE 802.11af systems are still able to continue transmitting packets. Considering the communication parameters and channel models compliant for the standards IEEE 802.11af and IEEE 802.22 system performances are investigated in terms of interfering packet rate and successful packet transmission rate for different scenarios and the improved results are presented. © 2018 IEEE.
Citation Count: 0
A Novel Indoor Channel Model for TVWS Communications based on Measurements
(IEEE, 2018) Baykaş, Tunçer; Erküçük, Serhat; Baykaş, Tunçer
In this paper we present an indoor measurement campaign for TV white space bands inside a university building. The measurement results are compared with different indoor propagation models in the literature. We observed large estimation errors for the total path loss value from all existing models. Consequently we are proposing a new indoor propagation model for TVWS frequencies which concatenates the effects of frequency dependent path loss with penetration losses due to walls and windows. Performance comparison with existing models show that the proposed model achieves superior performance compared to existing models in terms of Root-Mean-Squared Error (RMSE).