Kablosuz ATM (KATM), ses, veri ve video gibi farklı türdeki trafiklerin kablosuz ortam üzerinden ... more Kablosuz ATM (KATM), ses, veri ve video gibi farklı türdeki trafiklerin kablosuz ortam üzerinden iletimini amaçlar. KATM, ATM'in kablolu ortamda sağladığı servis kalitesi desteği ve yüksek veri iletim hızı gibi önemli özelliklerine sahiptir. Ortam Erişim Kontrol (OEK) katmanı, çok sayıda KATM kullanıcısına kablosuz ortam kaynaklarının etkin olarak paylaştırılmasını sağlar. Bu katmanın sunduğu servis kalitesi desteği, CBR, VBR, ABR ve UBR standart ATM trafik sınıflarını içermelidir. Bu çalışmada, TDMA/FDD tekniğine dayalı PRMA/DA ve MAC-GB KATM OEK protokollerinin, OPNET yazılımı kullanılarak gerçekleştirilen modelleri ve benzetimi sunulmaktadır. Video trafiğinin bu protokoller üzerine etkileri karşılaştırmalı olarak incelenerek, benzetim sonuçları değerlendirilmektedir.
Wireless Multimedia Sensor Networks (WMSNs) have recently attracted more attention and have contr... more Wireless Multimedia Sensor Networks (WMSNs) have recently attracted more attention and have contributed to new potential wireless sensor network (WSN) applications such as border surveillance, battlefield monitoring, target detection, target tracking and habitat monitoring. WMSNs carry heterogeneous traffic with different urgency and quality of service (QoS) requirements. While the need to minimize energy consumption is important in WSNs, offering QoS for multimedia transmission is a challenging issue due to resource constrained nature of sensor nodes, unreliable wireless links and unpredictable environments. Currently, there is a need for a new QoS aware, priority based cross layer Medium Access Control (MAC) protocol on WMSNs. Proposed new two tiered service differentiation mechanism and data rate adjustment scheme provides 8.7 times lower average end to end delay for urgent real time video traffic while providing lower end-to end delay for each urgent traffic class. Proposed mechanism has been focused on QoS provisioning at MAC layer for urgent traffic on especially military applications providing data rate adjustment by application layer.
A new method describing fixed wireless CAN networking is presented in this paper, exploiting the ... more A new method describing fixed wireless CAN networking is presented in this paper, exploiting the advantages of WATM as an over the air protocol, which include fixed-small cell size and connection negotiation. CAN over WATM mapping issues using encapsulation technique are also explained. The performance analysis of the proposed scheme is presented through computer simulation results provided by OPNET Modeler.
Uluslararası Teknolojik Bilimler Dergisi, Jul 9, 2019
Kablosuz Algılayıcı Ağ (KAA) kullanım alanlarının çeşitlenmesi, başarımlarının kolayca test edilm... more Kablosuz Algılayıcı Ağ (KAA) kullanım alanlarının çeşitlenmesi, başarımlarının kolayca test edilmesini gerekli kılmaktadır. Bu çalışmada, KAA'ların başarım değerlendirmesinde kullanılan temel ölçütlerin, analitik olarak elde edilmesi, benzetimlerinin gerçekleştirilmesi ve her iki yöntemle elde edilen sonuçların kıyaslanarak geçerliliklerinin doğrulanması hedeflenmektedir. Haberleşme ağlarını modelleme yöntemlerinin birbirlerine göre üstünlükleri ve zorlukları bulunmaktadır. Her yöntem tek başına kullanıldığında sistem başarımı hakkında sadece bazı kestirimler yapılabilmesini sağlamaktadır. Bununla birlikte tasarlanan bir sistemin farklı iki modelinden elde edilen sonuçların birbirleriyle örtüşmesi, sistemin doğruluğunu, kararlılığını ve gereksinimleri hangi ölçüde karşılayacağını gösterir ve sonuçların geçerliliğini teyit eder. Çalışmada, temel bir KAA OEK (Ortam Erişim Kontrol) protokolü gerçekleştirilmekte, analitik ve benzetim modelleri merkezi yapılı bir uygulama örneğinde kullanılmakta ve elde edilen sonuçlar sunulmaktadır. Analitik model esas alınarak düğüm enerji tüketimi ve ortalama uçtanuca paket gecikmesi hesaplanmakta, bunlar benzetim modelinden elde edilen sonuçlarla karşılaştırılarak sistemin başarım değerlendirmesi yapılmaktadır. Çalışma sonuçları, TDMA (Time Division Multiple Access, Zaman Bölmeli Çoklu Erişim) tabanlı KAA OEK için geçerlilik değerlendirmesinde kolayca kullanılabilir olduğundan, araştırmacılar ve uygulama geliştiriciler için bu konuda referans olma niteliği taşımaktadır.
Abstract Increasing throughput and meeting high packet delivery ratio demands in delay constraint... more Abstract Increasing throughput and meeting high packet delivery ratio demands in delay constraint Wireless Sensor Network (WSN) applications have triggered the use of hybrid multi radio and multichannel communication techniques. There are many works in literature on such classical techniques which are deployed in wireless structured networks like IEEE 802.11. Indeed, they cannot be directly utilized for wireless sensor devices due to energy, memory, radio and processor constraints. A number of protocols have been recently proposed to utilize multichannel communication techniques designed for WSNs. However, there is still a high demand of contribution for designing new channel allocation approaches for multi radio and multichannel communication to meet emerging WSN requirements. In this paper, we propose a new multichannel allocation approach, named Hybrid Multi-Channel Allocation for WSNs (HMCAWSN), based on hybrid Time Division Multiple Access (TDMA)–Frequency Division Multiple Access (FDMA) techniques and using dual radio with multichannel communication. A detailed simulation study indicates significant improvement on average and end-to-end delay results while keeping the sensor node energy consumptions at reasonable levels. Compared to its traditional and contemporary counterparts, the proposed HMCAWSN assures steady and high packet delivery ratios in large scale networking environments even with hundreds of sensor nodes.
TURKISH JOURNAL OF ELECTRICAL ENGINEERING & COMPUTER SCIENCES, 2016
Recently, wireless sensor networks (WSNs) have been widely employed in many different fields such... more Recently, wireless sensor networks (WSNs) have been widely employed in many different fields such as military, surveillance, health, agricultural, automation, and environmental monitoring. This paper presents a designed and implemented WSN-based man-overboard emergency discovery system, abbreviated as W-MEDS, that discovers the location of a person in emergency circumstances and runs an alarm system on a ship. The developed W-MEDS carries out a fast man-overboard (MOB) discovery and initiates the vital rescue procedure. It mainly consists of a WSN and a control and discovery system. When a MOB accident occurs, this situation is easily detected through the WSN nodes capable of real-time sensing (i.e. temperature, humidity, and acceleration) and the system enables location estimation. The control and discovery system analyzes and displays the received data from the WSN nodes. The most noteworthy advantage of the proposed W-MEDS is that it enables both real-time alarm monitoring and fast recovery. In addition to the implementation of the W-MEDS, considering hardness in performance evaluation of the real system, it has also been simulated in the OPNET Modeler to confirm the accuracy for different sizes and numbers of nodes.
The implementation of the remote control, monitoring and maintenance of industrial automation sys... more The implementation of the remote control, monitoring and maintenance of industrial automation systems based on real-time criteria is becoming more difficult as the distance increases. ATM is an important transport, switching, network management and backbone technology that offers different solutions to real-time communication with different classes of service. In this study, the effects on real-time communication of AAL 3/4 and AAL 5 classes of service of ATM were researched on a model in which the communication between WorldFIP industrial network nodes and ATM network nodes was provided over a bridge. First, a communication system consisting of a WorldFIP network, ATM network and bridge were modeled on a simulation tool and implemented. Afterwards, the system performance was analyzed under different loads within the classes of service AAL 3/4 and AAL 5. The analysis results have indicated that compared to AAL 5, AAL 3/4 better satisfies the real-time communication criteria. This result has shown that in both real-time access to a remote industrial automation systems and communication among remote industrial automation systems, ATM is preferable as a backbone and AAL 3/4 as the class of service.
The main purpose of this presented work is to develop a data embedding method based on a new digi... more The main purpose of this presented work is to develop a data embedding method based on a new digital image histogram modification approach. The proposed scheme fundamentally is concerned about the frequency of occurrence of the image brightness values of the cover image for the data embedding procedures. The proposed scheme effectively realizes both perceptual invisibility and statistical invisibility so that obtained covered images are highly robust against common perceptual and statistical steganalysis techniques. The scheme provides reasonably higher payload values than its counterparts, as well as providing comparatively improved PSNR results.
Recent Advances in Steganography 54 histogram modifications. The resulting covered/stego images a... more Recent Advances in Steganography 54 histogram modifications. The resulting covered/stego images are reasonably robust against main geometrical attacks, which do not change the image histogram, with high quality measurements in terms of human vision system as well as statistically. Rest of the chapter is organized as follows. Fundamentals of the digital image and image steganography are explained in the following section. Section three details both contemporary approaches to the histogram modification−based data hiding and the HSV method, its implementation, example applications in three well known images together with comparisons to those of the other classical counterparts and its steganalysis. And, final remarks are presented in the last section.
In this work, the effects of time Slot Allocation Strategies (SASs) on node energy consumption fo... more In this work, the effects of time Slot Allocation Strategies (SASs) on node energy consumption for time slot assignment-based Medium Access Control (MAC) protocols, generally preferred in Wireless Sensor Networks (WSNs) for energy efficiency, are comparatively studied. As Wireless Nodes' (WNs) energy consumption in WSNs determines the lifetime of network, it is of critical importance for application designers to know the best SAS to apply. Energy efficiency in WSNs can be maximized by employing an appropriate MAC while (i) assigning wireless medium resources efficiently and fairly among the WNs, (ii) minimizing packet collisions and (iii) avoiding overhearing. This paper aims at presenting and comparing the energy efficiency of transmit-based and receive-based SASs for multihop topologies used in WSN MAC. We have developed, modeled and analyzed both transmit-based and receive-based strategies. Based upon analytical models, comparative performance evaluations are presented. Besides, a detailed simulation study is carried out in a sample networking scenario by utilizing the OPNET Modeler software in order to confirm the analytical results. The study concludes that the receive-based SAS is at least five times more energy efficient than the transmit-based strategy in multi-hop network topologies, which is highly beneficial information to the WSN MAC designers.
This paper presents fundamental aspects of MPLS over ATM method, IP over ATM method and multimedi... more This paper presents fundamental aspects of MPLS over ATM method, IP over ATM method and multimedia application traffics with different quality of service (QoS) needs. Using a simulation program, the MPLS over ATM method providing ABR, CBR & VBR QoS support, and the IP over ATM method providing UBR QoS support for transferring data, voice and video traffics are modeled. Having simulated the models under varying loads, simulation results obtained and comparisons of the results are presented. Comparing the average delay and delay variation graphs, not only does MPLS over ATM method provide improved results for all of the multimedia applications but also overcomes the worst disadvantage of the IP over ATM method producing similar and erratic results for the data, voice and video application traffics.
A Comparative Performance Evaluation Study of IEEE 802.3 Wired and IEEE 802.11 Wireless LANs for ... more A Comparative Performance Evaluation Study of IEEE 802.3 Wired and IEEE 802.11 Wireless LANs for Multimedia Data Traffic. Cüneyt Bayılmış, İsmail Ertürk, Celal Çeken. Department of Electronics and Computer Education ...
Turkish Journal of Electrical Engineering Computer Sciences, Apr 17, 2013
Various methods for measuring perceptual image quality attempt to quantify the visibility of diff... more Various methods for measuring perceptual image quality attempt to quantify the visibility of differences between an original digital image and its distorted version using a variety of known properties of the human vision system (HVS). In this paper, we propose a simple and effective full-reference color image quality measure (CQM) based on reversible luminance and chrominance (YUV) color transformation and peak signal-to-noise ratio (PSNR) measure. The main motivation of this new measure relies on a unique feature of the human eye response to the luminance and color. Experimental studies about the applicability of the CQM on a well-known test image under 6 different distortions, both perceivable by the human vision system and with the same PSNR value (i.e. 27.67), are presented. The CQM results are obtained as 39.56, 38.93, 38.08, 37.43, 37.10, and 36.79 dB for each distorted image, showing that image quality of the first image is noticeably higher than the others with respect to the same PSNR value. This conclusion attests that using the CQM together with the traditional PSNR approach provides distinguished results.
CAN (Controller Area Network) has become one of the most advanced and important autobus protocols... more CAN (Controller Area Network) has become one of the most advanced and important autobus protocols in the communications industry for the last decade. Currently it is prominently used in many other industrial applications due to its high performance and superior ...
Page 1. Politeknik Dergisi Journal of Polytechnic Cilt:12 Sayı: 4 s.235-242, 2009 Vol: 12 No: 4 p... more Page 1. Politeknik Dergisi Journal of Polytechnic Cilt:12 Sayı: 4 s.235-242, 2009 Vol: 12 No: 4 pp. 235-242, 2009 235 Makale 30.10.2009 tarihinde gelmiş,28.12.2009 tarihinde yayınlanmak üzere kabul edilmiştir. N. BANDIRMALI, İ. ...
One of the biggest drawbacks of the wireless environment is the limited bandwidth. However, the u... more One of the biggest drawbacks of the wireless environment is the limited bandwidth. However, the users sharing this limited bandwidth have been increasing considerably. SDMA technique which entails using directional antennas allows to increase the capacity of a wireless network by separating users in the medium. In this paper, it has been presented how the capacity can be enhanced while the mean delay is reduced by using directional antennas in wireless networks employing TDMA/FDD MAC. Computer modeling and simulation of the wireless system studied are realized using OPNET Modeler. Preliminary simulation results are presented and the performance of the model using directional antennas is evaluated and compared consistently with the one using omnidirectional antennas.
Kablosuz ATM (KATM), ses, veri ve video gibi farklı türdeki trafiklerin kablosuz ortam üzerinden ... more Kablosuz ATM (KATM), ses, veri ve video gibi farklı türdeki trafiklerin kablosuz ortam üzerinden iletimini amaçlar. KATM, ATM'in kablolu ortamda sağladığı servis kalitesi desteği ve yüksek veri iletim hızı gibi önemli özelliklerine sahiptir. Ortam Erişim Kontrol (OEK) katmanı, çok sayıda KATM kullanıcısına kablosuz ortam kaynaklarının etkin olarak paylaştırılmasını sağlar. Bu katmanın sunduğu servis kalitesi desteği, CBR, VBR, ABR ve UBR standart ATM trafik sınıflarını içermelidir. Bu çalışmada, TDMA/FDD tekniğine dayalı PRMA/DA ve MAC-GB KATM OEK protokollerinin, OPNET yazılımı kullanılarak gerçekleştirilen modelleri ve benzetimi sunulmaktadır. Video trafiğinin bu protokoller üzerine etkileri karşılaştırmalı olarak incelenerek, benzetim sonuçları değerlendirilmektedir.
Wireless Multimedia Sensor Networks (WMSNs) have recently attracted more attention and have contr... more Wireless Multimedia Sensor Networks (WMSNs) have recently attracted more attention and have contributed to new potential wireless sensor network (WSN) applications such as border surveillance, battlefield monitoring, target detection, target tracking and habitat monitoring. WMSNs carry heterogeneous traffic with different urgency and quality of service (QoS) requirements. While the need to minimize energy consumption is important in WSNs, offering QoS for multimedia transmission is a challenging issue due to resource constrained nature of sensor nodes, unreliable wireless links and unpredictable environments. Currently, there is a need for a new QoS aware, priority based cross layer Medium Access Control (MAC) protocol on WMSNs. Proposed new two tiered service differentiation mechanism and data rate adjustment scheme provides 8.7 times lower average end to end delay for urgent real time video traffic while providing lower end-to end delay for each urgent traffic class. Proposed mechanism has been focused on QoS provisioning at MAC layer for urgent traffic on especially military applications providing data rate adjustment by application layer.
A new method describing fixed wireless CAN networking is presented in this paper, exploiting the ... more A new method describing fixed wireless CAN networking is presented in this paper, exploiting the advantages of WATM as an over the air protocol, which include fixed-small cell size and connection negotiation. CAN over WATM mapping issues using encapsulation technique are also explained. The performance analysis of the proposed scheme is presented through computer simulation results provided by OPNET Modeler.
Uluslararası Teknolojik Bilimler Dergisi, Jul 9, 2019
Kablosuz Algılayıcı Ağ (KAA) kullanım alanlarının çeşitlenmesi, başarımlarının kolayca test edilm... more Kablosuz Algılayıcı Ağ (KAA) kullanım alanlarının çeşitlenmesi, başarımlarının kolayca test edilmesini gerekli kılmaktadır. Bu çalışmada, KAA'ların başarım değerlendirmesinde kullanılan temel ölçütlerin, analitik olarak elde edilmesi, benzetimlerinin gerçekleştirilmesi ve her iki yöntemle elde edilen sonuçların kıyaslanarak geçerliliklerinin doğrulanması hedeflenmektedir. Haberleşme ağlarını modelleme yöntemlerinin birbirlerine göre üstünlükleri ve zorlukları bulunmaktadır. Her yöntem tek başına kullanıldığında sistem başarımı hakkında sadece bazı kestirimler yapılabilmesini sağlamaktadır. Bununla birlikte tasarlanan bir sistemin farklı iki modelinden elde edilen sonuçların birbirleriyle örtüşmesi, sistemin doğruluğunu, kararlılığını ve gereksinimleri hangi ölçüde karşılayacağını gösterir ve sonuçların geçerliliğini teyit eder. Çalışmada, temel bir KAA OEK (Ortam Erişim Kontrol) protokolü gerçekleştirilmekte, analitik ve benzetim modelleri merkezi yapılı bir uygulama örneğinde kullanılmakta ve elde edilen sonuçlar sunulmaktadır. Analitik model esas alınarak düğüm enerji tüketimi ve ortalama uçtanuca paket gecikmesi hesaplanmakta, bunlar benzetim modelinden elde edilen sonuçlarla karşılaştırılarak sistemin başarım değerlendirmesi yapılmaktadır. Çalışma sonuçları, TDMA (Time Division Multiple Access, Zaman Bölmeli Çoklu Erişim) tabanlı KAA OEK için geçerlilik değerlendirmesinde kolayca kullanılabilir olduğundan, araştırmacılar ve uygulama geliştiriciler için bu konuda referans olma niteliği taşımaktadır.
Abstract Increasing throughput and meeting high packet delivery ratio demands in delay constraint... more Abstract Increasing throughput and meeting high packet delivery ratio demands in delay constraint Wireless Sensor Network (WSN) applications have triggered the use of hybrid multi radio and multichannel communication techniques. There are many works in literature on such classical techniques which are deployed in wireless structured networks like IEEE 802.11. Indeed, they cannot be directly utilized for wireless sensor devices due to energy, memory, radio and processor constraints. A number of protocols have been recently proposed to utilize multichannel communication techniques designed for WSNs. However, there is still a high demand of contribution for designing new channel allocation approaches for multi radio and multichannel communication to meet emerging WSN requirements. In this paper, we propose a new multichannel allocation approach, named Hybrid Multi-Channel Allocation for WSNs (HMCAWSN), based on hybrid Time Division Multiple Access (TDMA)–Frequency Division Multiple Access (FDMA) techniques and using dual radio with multichannel communication. A detailed simulation study indicates significant improvement on average and end-to-end delay results while keeping the sensor node energy consumptions at reasonable levels. Compared to its traditional and contemporary counterparts, the proposed HMCAWSN assures steady and high packet delivery ratios in large scale networking environments even with hundreds of sensor nodes.
TURKISH JOURNAL OF ELECTRICAL ENGINEERING & COMPUTER SCIENCES, 2016
Recently, wireless sensor networks (WSNs) have been widely employed in many different fields such... more Recently, wireless sensor networks (WSNs) have been widely employed in many different fields such as military, surveillance, health, agricultural, automation, and environmental monitoring. This paper presents a designed and implemented WSN-based man-overboard emergency discovery system, abbreviated as W-MEDS, that discovers the location of a person in emergency circumstances and runs an alarm system on a ship. The developed W-MEDS carries out a fast man-overboard (MOB) discovery and initiates the vital rescue procedure. It mainly consists of a WSN and a control and discovery system. When a MOB accident occurs, this situation is easily detected through the WSN nodes capable of real-time sensing (i.e. temperature, humidity, and acceleration) and the system enables location estimation. The control and discovery system analyzes and displays the received data from the WSN nodes. The most noteworthy advantage of the proposed W-MEDS is that it enables both real-time alarm monitoring and fast recovery. In addition to the implementation of the W-MEDS, considering hardness in performance evaluation of the real system, it has also been simulated in the OPNET Modeler to confirm the accuracy for different sizes and numbers of nodes.
The implementation of the remote control, monitoring and maintenance of industrial automation sys... more The implementation of the remote control, monitoring and maintenance of industrial automation systems based on real-time criteria is becoming more difficult as the distance increases. ATM is an important transport, switching, network management and backbone technology that offers different solutions to real-time communication with different classes of service. In this study, the effects on real-time communication of AAL 3/4 and AAL 5 classes of service of ATM were researched on a model in which the communication between WorldFIP industrial network nodes and ATM network nodes was provided over a bridge. First, a communication system consisting of a WorldFIP network, ATM network and bridge were modeled on a simulation tool and implemented. Afterwards, the system performance was analyzed under different loads within the classes of service AAL 3/4 and AAL 5. The analysis results have indicated that compared to AAL 5, AAL 3/4 better satisfies the real-time communication criteria. This result has shown that in both real-time access to a remote industrial automation systems and communication among remote industrial automation systems, ATM is preferable as a backbone and AAL 3/4 as the class of service.
The main purpose of this presented work is to develop a data embedding method based on a new digi... more The main purpose of this presented work is to develop a data embedding method based on a new digital image histogram modification approach. The proposed scheme fundamentally is concerned about the frequency of occurrence of the image brightness values of the cover image for the data embedding procedures. The proposed scheme effectively realizes both perceptual invisibility and statistical invisibility so that obtained covered images are highly robust against common perceptual and statistical steganalysis techniques. The scheme provides reasonably higher payload values than its counterparts, as well as providing comparatively improved PSNR results.
Recent Advances in Steganography 54 histogram modifications. The resulting covered/stego images a... more Recent Advances in Steganography 54 histogram modifications. The resulting covered/stego images are reasonably robust against main geometrical attacks, which do not change the image histogram, with high quality measurements in terms of human vision system as well as statistically. Rest of the chapter is organized as follows. Fundamentals of the digital image and image steganography are explained in the following section. Section three details both contemporary approaches to the histogram modification−based data hiding and the HSV method, its implementation, example applications in three well known images together with comparisons to those of the other classical counterparts and its steganalysis. And, final remarks are presented in the last section.
In this work, the effects of time Slot Allocation Strategies (SASs) on node energy consumption fo... more In this work, the effects of time Slot Allocation Strategies (SASs) on node energy consumption for time slot assignment-based Medium Access Control (MAC) protocols, generally preferred in Wireless Sensor Networks (WSNs) for energy efficiency, are comparatively studied. As Wireless Nodes' (WNs) energy consumption in WSNs determines the lifetime of network, it is of critical importance for application designers to know the best SAS to apply. Energy efficiency in WSNs can be maximized by employing an appropriate MAC while (i) assigning wireless medium resources efficiently and fairly among the WNs, (ii) minimizing packet collisions and (iii) avoiding overhearing. This paper aims at presenting and comparing the energy efficiency of transmit-based and receive-based SASs for multihop topologies used in WSN MAC. We have developed, modeled and analyzed both transmit-based and receive-based strategies. Based upon analytical models, comparative performance evaluations are presented. Besides, a detailed simulation study is carried out in a sample networking scenario by utilizing the OPNET Modeler software in order to confirm the analytical results. The study concludes that the receive-based SAS is at least five times more energy efficient than the transmit-based strategy in multi-hop network topologies, which is highly beneficial information to the WSN MAC designers.
This paper presents fundamental aspects of MPLS over ATM method, IP over ATM method and multimedi... more This paper presents fundamental aspects of MPLS over ATM method, IP over ATM method and multimedia application traffics with different quality of service (QoS) needs. Using a simulation program, the MPLS over ATM method providing ABR, CBR & VBR QoS support, and the IP over ATM method providing UBR QoS support for transferring data, voice and video traffics are modeled. Having simulated the models under varying loads, simulation results obtained and comparisons of the results are presented. Comparing the average delay and delay variation graphs, not only does MPLS over ATM method provide improved results for all of the multimedia applications but also overcomes the worst disadvantage of the IP over ATM method producing similar and erratic results for the data, voice and video application traffics.
A Comparative Performance Evaluation Study of IEEE 802.3 Wired and IEEE 802.11 Wireless LANs for ... more A Comparative Performance Evaluation Study of IEEE 802.3 Wired and IEEE 802.11 Wireless LANs for Multimedia Data Traffic. Cüneyt Bayılmış, İsmail Ertürk, Celal Çeken. Department of Electronics and Computer Education ...
Turkish Journal of Electrical Engineering Computer Sciences, Apr 17, 2013
Various methods for measuring perceptual image quality attempt to quantify the visibility of diff... more Various methods for measuring perceptual image quality attempt to quantify the visibility of differences between an original digital image and its distorted version using a variety of known properties of the human vision system (HVS). In this paper, we propose a simple and effective full-reference color image quality measure (CQM) based on reversible luminance and chrominance (YUV) color transformation and peak signal-to-noise ratio (PSNR) measure. The main motivation of this new measure relies on a unique feature of the human eye response to the luminance and color. Experimental studies about the applicability of the CQM on a well-known test image under 6 different distortions, both perceivable by the human vision system and with the same PSNR value (i.e. 27.67), are presented. The CQM results are obtained as 39.56, 38.93, 38.08, 37.43, 37.10, and 36.79 dB for each distorted image, showing that image quality of the first image is noticeably higher than the others with respect to the same PSNR value. This conclusion attests that using the CQM together with the traditional PSNR approach provides distinguished results.
CAN (Controller Area Network) has become one of the most advanced and important autobus protocols... more CAN (Controller Area Network) has become one of the most advanced and important autobus protocols in the communications industry for the last decade. Currently it is prominently used in many other industrial applications due to its high performance and superior ...
Page 1. Politeknik Dergisi Journal of Polytechnic Cilt:12 Sayı: 4 s.235-242, 2009 Vol: 12 No: 4 p... more Page 1. Politeknik Dergisi Journal of Polytechnic Cilt:12 Sayı: 4 s.235-242, 2009 Vol: 12 No: 4 pp. 235-242, 2009 235 Makale 30.10.2009 tarihinde gelmiş,28.12.2009 tarihinde yayınlanmak üzere kabul edilmiştir. N. BANDIRMALI, İ. ...
One of the biggest drawbacks of the wireless environment is the limited bandwidth. However, the u... more One of the biggest drawbacks of the wireless environment is the limited bandwidth. However, the users sharing this limited bandwidth have been increasing considerably. SDMA technique which entails using directional antennas allows to increase the capacity of a wireless network by separating users in the medium. In this paper, it has been presented how the capacity can be enhanced while the mean delay is reduced by using directional antennas in wireless networks employing TDMA/FDD MAC. Computer modeling and simulation of the wireless system studied are realized using OPNET Modeler. Preliminary simulation results are presented and the performance of the model using directional antennas is evaluated and compared consistently with the one using omnidirectional antennas.
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