Yazar "Erturk, Ismail" seçeneğine göre listele
Listeleniyor 1 - 11 / 11
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe A new color image quality measure based on YUV transformation and PSNR for human vision system(Tubitak Scientific & Technological Research Council Turkey, 2013) Yalman, Yildiray; Erturk, IsmailVarious 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.Öğe A new MAC protocol for broadband wireless communications and its performance evaluation(Springer, 2014) Atmaca, Sedat; Karahan, Alper; Ceken, Celal; Erturk, IsmailThis paper presents a new Time Division Multiple Access/Frequency Division Duplexing (TDMA/FDD) based Medium Access Control (MAC) protocol for broadband wireless networks, supporting Quality of Service (QoS) for real-time multimedia applications. It also gives the Call Blocking Probability (CBP), packet end-to-end delay and utilization analysis of different service classes, as they are most essential performance criterions in broadband wireless network assessment. The Connection Admission Control (CAC) mechanism in the proposed MAC efficiently organizes the bandwidth allocation for different service classes by means of a fairness based scheduling algorithm. In addition, the simulation model of the proposed MAC scheme is realized by using OPNET Modeler network simulator. The results of the analytical calculations for the CBPs are compared to those of the simulation of the proposed MAC, thus validity of the MAC protocol is proved.Öğe A Novel Cross-layer Routing Protocol for Increasing Packet Transfer Reliability in Mobile Sensor Networks(Springer, 2014) Cakici, Suleyman; Erturk, Ismail; Atmaca, Sedat; Karahan, AlperIn mobile sensor networks (MSNs), sensor data is generally transferred via mobile sensor nodes by multi-hop fashion. Because of the mobility of the nodes in the network, the efficient routing protocols are needed to ensure end-to-end route reliability while incurring minimal power consumption and packet delay. In this study, we developed a new routing protocol to meet these requirements for MSNs based on a cross-layer interaction among five reference layers (application, transport, network, MAC and physical). The proposed protocol primarily exploits the idea of interaction among these five layers all-in-one protocol. Its primary goals are (i) to discover the most reliable route in network, (ii) to sustain the route reliability and (iii) to be energy efficient and delay aware. It has been designed, modeled and simulated by using OPNET Modeler simulation software. The simulation results of the proposed protocol have been compared to three well known routing protocols (i.e., AODV, Leach-Mobile, CBR-Mobile). According to the obtained results, the proposed protocol outperforms its counterparts in terms of route reliability and end-to-end delay performances.Öğe An event-driven WSN MAC protocol design based on active node and dynamic time slot allocation(Tubitak Scientific & Technological Research Council Turkey, 2013) Sazak, Nukhet; Erturk, Ismail; Koklukaya, Etem; Cakiroglu, MuratThe unique features of wireless sensor networks (WSNs) make them suitable for a wide range of applications in many different areas. However, with many of the protocols and algorithms used in traditional wireless networks, it is usually neither feasible nor possible to apply them directly to WSNs due to the strict resource constraints of tiny sensor nodes. Moreover, application-specific approaches for communication protocols are usually imposed since WSN applications have distinct requirements. In this study, event-driven WSN applications, where a number of sensor nodes are randomly and densely deployed in remote and difficult to reach locations, are targeted. In such applications, energy efficiency and latency are crucial design parameters since replacing or recharging the batteries of sensor nodes is extremely difficult, and any sensed data should be transmitted eventually. Considering this aspect, conventional time division multiple access-based medium access control (MAC) protocols are not well suited, although there are a few MAC protocols specifically designed for event-driven WSNs. In this paper, we introduce a MAC protocol, named modified bit-map assisted (M-BMA), for event-driven WSN applications, designed by employing a new active node determination method (ANDM) and dynamic time slot allocation approach. Utilizing the proposed ANDM, we present that the M-BMA well supersedes its classical counterpart, offering up to approximately 49% better energy usage as well as up to about 68% fewer message delays.Öğe Design and implementation of a man-overboard emergency discovery system based on wireless sensor networks(Tubitak Scientific & Technological Research Council Turkey, 2016) Sevin, Abdullah; Bayilmis, Cuneyt; Erturk, Ismail; Ekiz, Huseyin; Karaca, AhmetRecently, 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.Öğe Effects of transmit-based and receive-based slot allocation strategies on energy efficiency in WSN MACs(Elsevier, 2014) Karahan, Alper; Erturk, Ismail; Atmaca, Sedat; Cakici, SuleymanIn 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 multi-hop 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. (C) 2013 Elsevier B.V. All rights reserved.Öğe Energy Efficient Hybrid MAC Protocol for Large Scale Wireless Sensor Networks(Ieee, 2015) Karahan, Alper; Erturk, Ismail; Atmaca, Sedat; Cakici, SuleymanIn this study, a hybrid, energy efficient MAC (Medium Access Control) protocol has been developed for usage in dense WSN (Wireless Sensor Network) applications. In the designed hybrid MAC, favorable aspects of both CSMA (Carrier Sense Multiple Access) and TDMA (Time Division Multiple Access) techniques are considered. Consequently, a MAC protocol which is more energy efficient than both CSMA and TDMA-based MAC protocols is aimed. Therefore, with the combination of CSMA which responses to the events rapidly and TDMA which reduces the collisions and unnecessary channel listening, high system throughput and node energy efficiency are obtained.Öğe Secret data embedding scheme modifying the frequency of occurrence of image brightness values(Springer India, 2014) Yalman, Yildiray; Erturk, IsmailThe 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.Öğe SRRA: SMART REDUNDANCY RECONFIGURATION ALGORITHM FOR COMMUNICATION SATELLITE PAYLOAD(Gazi Univ, Fac Engineering Architecture, 2014) Gulgonul, Senol; Koklukaya, Etem; Erturk, Ismail; Tesneli, Ahmet Y.Redundancy is provided by using multiport switches which are connecting equipment in communication satellite payload systems. In case of a failure, signal path is re-routed by changing suitable switch positions. Smart Redundancy Reconfiguration Algorithm (SRRA) is a novel algorithm, able to model any payload system and to find paths recursively to redundant equipment. Results of the SRRA are verified by means of comparing them to those of the ICAREF commercial software which is currently being used in TURKSAT-3A satellite operations. SRRA can find all paths connecting given input(s) to any output(s) by taking number of interruptions and number of switches crossed constraints into account.Öğe Two Tiered Service Differentiation and Data Rate Adjustment Scheme for WMSNs Cross Layer MAC(Ieee, 2014) Ozen, Yunus; Bayilmis, Cuneyt; Bandirmali, Necla; Erturk, IsmailWireless 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.Öğe WSNSec: A scalable data link layer security protocol for WSNs(Elsevier, 2012) Bandirmali, Necla; Erturk, IsmailA Wireless Sensor Network (WSN) link layer security protocol called WSNSec is proposed in this paper. The effective usage of limited sensor node resources is of high importance in WSN security protocol design and implementation. In addition, research on increased security for the WSNs employed in especially military and health areas recently receives a remarkable attention as primarily focused on in this presented work. The WSNSec smoothly combines the advantageous aspects of the Scalable Encryption Algorithm (SEA) with the Counter Mode (CTR) and Cipher Block Chaining-Message Authentication Code (CBC-MAC) approaches. It provides not only high data confidentiality but also message authentication and integrity functions. The WSNSec security level can be boosted dynamically if required. It has been shown that using the proposed WSNSec with the 192-bit data block/key size has a trivial increase on the memory usage and energy consumption while providing an extremely high level of security compared to the traditional TinySEC. In addition, modeling and simulation of a WSN employing the proposed WSNSec have been realized using the OPNET Modeler software. The simulation results reveal that the ratios of the delays resulted from the particular use of both WSNSec and TinySEC to the total end to end delays converge at 13% for increasing the network load. Therefore the WSNSec provides a better delay performance in highly scalable applications. (C) 2011 Elsevier B.V. All rights reserved.
