Erküçük, Serhat

Erküçük, Serhat

Name Variants

Erküçük, Serhat
S.,Erküçük
S. Erküçük
Serhat, Erküçük
Erkucuk, Serhat
S.,Erkucuk
S. Erkucuk
Serhat, Erkucuk
Erküçük, S.
Erküçük,S.

Job Title

Prof. Dr.

Email Address

Serkucuk@khas.edu.tr

Main Affiliation

Electrical-Electronics Engineering

Status

Former Staff

Full item page

Scholarly Output

67

Articles

19

Citation Count

0

Supervised Theses

9 Scholarly Output Search Results

Now showing 1 - 10 of 10

Coexistence of Cognitive Radio Based Networks in Tv White Space
(Kadir Has Üniversitesi, 2016) Karatalay, Onur; Erküçük, Serhat; Erküçük, Serhat
Due to increasing data rates in enhancing wireless communications RF spectrum which is one of the most crucial natural sources has become more valuable. in order to utilize the limited spectrum e_ciently and solve the scarcity problem regulatory agencies granted unlicensed networks or secondary users (SUs) access to licensed bands for wireless communication with the condition that they should not cause harmful interference to primary users (SUs). Cognitive radio (CR) technology enables devices to access the spectrum opportunistically. Using CR based networks licensed bands can be utilized more e_ectively for wireless communications. TV White Space (TVWS) refers to portions of the RF spectrum that was reserved only for licensed terrestrial TV broadcasting and is opened to unlicensed use under regulatory conditions. While regulations protect licensed systems in TVWS from harmful interference interference prevention 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 that the selected frequency band is occupied. in this dissertation a busy tone based coexistence algorithm is proposed for wireless local area networks (WLANs) operating in TVWS (i.e. iEEE 802.11af based networks) where wireless regional area network (WRAN) (i.e. iEEE 802.22 based network) is assumed to be the busy tone broadcaster. The proposed algorithm is analyzed in detail considering the e_ects of log-normal shadowing client distribution around the access point and the number of clients where exact interfering packet rate and successful packet transmission rate expressions are obtained and validated by simulations for di_erent 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 regional and local area networks where interference among networks is not regulated such as in TVWS bands.
Citation - WoS: 1
Busy Tone Implementation for Coexistence of Ieee 802.22 and 802.11 Af Systems
(IEEE, 2015) Karatalay, Onur; Baykaş, Tunçer; Erküçük, Serhat; 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 - WoS: 4
Performance Investigation of Ieee 802.11af Systems Under Realistic Channel Conditions
(IEEE, 2015) Macit, Mustafa Can; Şenol, Habib; Şenol, Habib; Erküçük, Serhat; Erküçük, Serhat
As the analog TV broadcasting channels have become less frequently used in the last decade there has been a great interest in these frequency bands for the deployment of metropolitan local and personal area networks. Among them the local area network standard IEEE 802.11af defines PHY and MAC layer implementation of such networks in these unused frequency bands also named television white space (TVWS). According to the standard the systems may use contiguous or non-contiguous channels during their operation depending on the channel availability. In this paper we investigate in detail the performance of different operation modes of these systems under realistic channel conditions. While the perfect knowledge of channel would result in similar system performances as the number of in-between-bands occupying the non-contiguous modes is increased the channel estimation performance degrades drastically which is quantified in this study. In addition it is shown that determining the true locations of multipaths heavily relies on the selected channel resolution and has a significant effect on the system performance. Numerical examples are given to demonstrate the effects of both the non-contiguous operation modes and the selected channel resolution.
Citation - Scopus: 2
Busy Tone Implementation for Coexistence of Ieee 802.22 and 802.11af Systems
(Institute of Electrical and Electronics Engineers Inc., 2015) Karatalay, O.; Baykaş, Tunçer; Erküçük, S.; Erküçük, Serhat; 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 - Scopus: 1
Busy Tone Based Power Control For Coordination Of Ieee 802.11af And 802.22 System [ıeee 802.11af ve 802.22 Sistemlerinin Uyumlu Çalışmaları için Meşgul Ton Tabanlı Güç Kontrolü]
(Institute of Electrical and Electronics Engineers Inc., 2017) Ulgen, Oguz; Baykaş, Tunçer; Erküçük, Serhat; 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 - WoS: 1
Citation - Scopus: 2
A New Approach for Coexistence of Ieee 802.11af and Ieee 802.22 Systems
(Institute of Electrical and Electronics Engineers Inc., 2018) Ulgen, Oguz; Baykaş, Tunçer; 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 - WoS: 4
Citation - Scopus: 5
Analysis of Extended Busy Tone Performance for Coexistence Between Wran and Wlan Tvws Networks
(IEEE, 2015) Karatalay, Onur; Baykaş, Tunçer; Erküçük, Serhat; 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 - WoS: 1
Busy Tone Based Power Control for Coordination of Iffy 802.11af and 802.22 System
(IEEE, 2017) Ülgen, Oğuz; Baykaş, Tunçer; Erküçük, Serhat; 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.
Power Control and Multihop Communication Approaches for the Coexistence of Ieee 802.11af and Ieee 802.22 Networks in Tv White Space
(Kadir Has Üniversitesi, 2017) Ulgen, Oguz; Erküçük, Serhat; Erküçük, Serhat
Communication networks have been among the most important research fields of scientists in the recent years. Researches have been conducted in various different topics and contents as technology has evolved. As some new technologies become available some technologies become out of date. One of the outdated technologies in recent years is the analog TV broadcasting. With the shift from analog TV broadcasting to digital TV broadcasting the frequency bands of old analog TV broadcasting has become available for the implementation of new technologies. This spectrum is called TV White Space (TVWS). Due to wide coverage and good signal transmission properties in TVWS researchers and engineers have focused on developing standards for this valuable spectrum. Within the same period of time another new technology based on cognitive radios has been investigated and implemented. Among the standards and technologies developed for TV White Space one focus area has been to allow the access of unlicensed (secondary) users to the spectrum. Even though solutions for protecting the licensed (primary) users has been successful researches for protecting the secondary users in coexistence have not given conclusive results. Several of these researches are on the coexistence of iEEE 802.22 wireless regional area network and iEEE 802.11af wireless local area network. However due to the nature of two heterogeneous networks not communicating with each other there is a need for further coexistence mechanisms. in this thesis different from the earlier works busy tone based power control and multihop communication algorithms are implemented for different coexistence scenarios of iEEE 802.22 and iEEE 802.11af. interfering packet rate results and successful packet transmission rate results obtained via computer simulations and improved results are presented. in addition interfering packet rate results and successful packet transmission rate results are presented under realistic channel models ii and log-normal shadowing. The presented results are important to improve the results of existing busy tone based approaches.
Citation - WoS: 4
Citation - Scopus: 7
Realistic Channel Estimation of Ieee 802.11af Systems in Tv White Space
(Institute of Electrical and Electronics Engineers Inc., 2020) Başaran, Mehmet; Şenol, Habib; Macit, Mustafa Can; Erküçük, Serhat; Şenol, Habib; Erküçük, Serhat
This work investigates the realistic performance of IEEE 802.11af systems released for the efficient spectrum utilization of TV white space (TVWS). These systems are operated over many contiguous or non-contiguous channels based on the TVWS frequency band availability. Accordingly, we consider realistic channel estimation for TVWS system and analyze the corresponding system performance of linear minimum mean square error (LMMSE) and orthogonal matching pursuit (OMP) algorithms. While LMMSE estimates channel path gains assuming perfectly known tap delay locations, OMP estimates both channel path gains and delays. Owing to the realistic implementation and estimating the full channel state information (CSI) of sparse channels, we mainly assess the OMP performance together with the LMMSE estimation for comparison in terms of channel reconstruction and symbol detection errors. To address the channel estimation performance, Bayesian Cramer-Rao bound is derived theoretically for both perfect and imperfect CSI, and confirmed with the simulations. Simulation results demonstrate that the realistic OMP-based symbol detection performance is found to be only 1-2 dB inferior compared to the near-optimal LMMSE-based estimation with known delays in low and medium signal-to-noise-ratio regions, where communication mainly occurs in practice. In addition, the effects of channel multipath number, channel resolution and operation modes on the system performance are studied for different scenarios. The results of this work are important for the practical implementation of IEEE 802.11af-based systems.