Researcher: Kaytaz, Umuralp
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Kaytaz, Umuralp
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Publication Metadata only Distributed deep reinforcement learning with wideband sensing for dynamic spectrum access(Ieee, 2020) Ucar, Seyhan; N/A; Department of Computer Engineering; Department of Electrical and Electronics Engineering; Kaytaz, Umuralp; Akgün, Barış; Ergen, Sinem Çöleri; PhD Student; Faculty Member; Faculty Member; Department of Computer Engineering; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; 258784; 7211Wideband spectrum sensing (WBS) has been a critical issue for communication system designers and specialists to monitor and regulate the wireless spectrum. Detecting and identifying the existing signals in a continuous manner enable orchestrating signals through all controllable dimensions and enhancing resource usage efficiency. This paper presents an investigation on the application of deep learning (DL)-based algorithms within the WBS problem while also providing comparisons to the conventional recursive thresholding-based solution. For this purpose, two prominent object detectors, You Only Learn One Representation (YOLOR) and Detectron2, are implemented and fine-tuned to complete these tasks for WBS. The power spectral densities (PSDs) belonging to over-the-air (OTA) collected signals within the wide frequency range are recorded as images that constitute the signal signatures (i.e., the objects of interest) and are fed through the input of the above-mentioned learning and evaluation processes. The main signal types of interest are determined as the cellular and broadcast types (i.e., GSM, UMTS, LTE and Analogue TV) and the single-tone. With a limited amount of captured OTA data, the DL-based approaches YOLOR and Detectron2 are seen to achieve a classification rate of 100% and detection rates of 85% and 69%, respectively, for a nonzero intersection over union threshold. The preliminary results of our investigation clearly show that both object detectors are promising to take on the task of wideband signal detection and identification, especially after an extended data collection campaign.Publication Metadata only A performance comparison of single-radio multi-channel medium access control protocols(Ieee, 2020) Ucar, Seyhan; N/A; Department of Electrical and Electronics Engineering; Kaytaz, Umuralp; Ergen, Sinem Çöleri; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 7211Single-radio multi-channel Medium Access Control (MAC) protocols aim to transmit in parallel on distinct channels while reducing the hardware cost. Although a variety of MAC protocols have been proposed in this context, no detailed classification and performance comparison is available. In this paper, we first classify previous efforts by their rendezvous characteristics as single- and multi-rendezvous protocols. Multirendezvous protocols have the capability of supporting simultaneous handshaking on different channels whereas with single-rendezvous protocols only asynchronous channel negotiations are allowed. Then, we further classify these protocols according to their spectrum decision mechanisms. We demonstrate the functionality of single- and multi-rendezvous protocols under different scenarios via extensive simulations. Our findings show that multi-rendezvous protocol performs better when the transmission range is low and less number of channels is available. Single-rendezvous protocols, on the other hand, are more suitable for networks with larger traffic loads due to their slot-based decision-making schemes. / Tek telsiz çok kanallI Ortam Erişim Kontrolü (MAC) protokolleri, donanIm maliyetini düşürürken farklI kanallarda paralel iletimi amaçlamaktadIr. Bu bağlamda çeşitli MAC protokolleri önerilmiş olmasIna rağmen, ayrIntIlI bir sInIflandIrma ve performans karşIlaştIrmasI mevcut değildir. Bu çalIşmamIzda, öncelikle mevcut protokolleri tek ve çok randevulu protokoller olarak buluşturma özelliklerine göre sInIflandIrmaktayIz. Çok randevulu protokoller, farklI kanallarda eşzamanlI el sIkIşmasInI destekleme yeteneğine sahipken, tek randevulu protokoller yalnIzca eşzamanlI olmayan kanal görüşmelerine izin vermektedir. Daha sonra, bu protokolleri spektrum karar mekanizmalarIna göre tekrar sInIflandIrmaktayIz. KapsamlI başarIm ölçümü aracIlIğIyla tek ve çok randevulu protokollerin işlevselliğini farklI senaryolar altInda göstermekteyiz. BulgularImIz, çok randevulu protokolün düşük iletim menzili ve az sayIda kanal bulunduğunda daha iyi performans sergilediğini göstermektedir. Diğer yandan, tek randevulu protokoller, sIra tabanlI karar planlamalarI nedeniyle büyük trafik yükü olan ağlar için daha uygun olmaktadIr.Publication Metadata only A performance comparison of single-radio multichannel medium access control protocols(Institute of Electrical and Electronics Engineers Inc., 2020) Department of Electrical and Electronics Engineering; N/A; N/A; Ergen, Sinem Çöleri; Uçar, Seyhan; Kaytaz, Umuralp; Faculty Member; PhD Student; PhD Student; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 7211; N/A; N/ASingle-radio multi-channel Medium Access Control (MAC) protocols aim to transmit in parallel on distinct channels while reducing the hardware cost. Although a variety of MAC protocols have been proposed in this context, no detailed classification and performance comparison is available. In this paper, we first classify previous efforts by their rendezvous characteristics as single- and multi-rendezvous protocols. Multirendezvous protocols have the capability of supporting simultaneous handshaking on different channels whereas with single-rendezvous protocols only asynchronous channel negotiations are allowed. Then, we further classify these protocols according to their spectrum decision mechanisms. We demonstrate the functionality of single- and multi-rendezvous protocols under different scenarios via extensive simulations. Our findings show that multi-rendezvous protocol performs better when the transmission range is low and less number of channels is available. Single-rendezvous protocols, on the other hand, are more suitable for networks with larger traffic loads due to their slot-based decision-making schemes.Publication Metadata only Index-based channel hopping for multi-rendezvous multi-channel MAC(IEEE-Inst Electrical Electronics Engineers Inc, 2020) Ucar, Seyhan; N/A; Department of Electrical and Electronics Engineering; Kaytaz, Umuralp; Ergen, Sinem Çöleri; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 7211Multi-channel Medium Access Control (MAC) protocols aim to transmit in parallel on distinct channels in order to increase spectrum utilization. In this letter, we consider dynamic multi-channel access problem with independent and stochastically identical channels. We formulate the problem as a Restless Multi-Armed Bandit (RMAB) process and propose a novel load-adaptive frequency hopping method, namely Index-Based Channel Hopping (IBCH) algorithm, with the goal of optimal spectrum allocation and throughput maximization. We classify previous efforts by their spectrum decision mechanisms and rendezvous characteristics as single- and multi-rendezvous protocols. Later on, we compare performance of IBCH with various protocols from both rendezvous classes at varying transmission range, network size and spectrum availability. Simulation results show that IBCH significantly outperforms other spectrum assignment methods from both rendezvous classes.