Garantili adil durum bilgisiz merkez ağ mimarisi değerlendirmesi.

The problem of providing Quality of Service (QoS) in the Internet has been an extremely active area of research and various mechanisms have been proposed related to this subject. Developing network applications have requirements such as bounded delay, jitter, minimum bandwidth and maximum loss rate. There is also a need to support large bandwidth networks because of growing link speeds. Previous QoS efforts did not fully satisfy all these needs of future networks but more recent approaches aim to be both scalable and rich in the provision of guaranteed services. Consequently core-stateless systems received much attention in recent years because of their scalability in supporting per-flow QoS. The property of not maintaining any per-flow state in the core routers is known as being core-stateless. In this thesis study, the need for core-stateless network architectures is pointed out and a literature survey about these schemes is carried out. Core-Stateless Guaranteed Fair (CSGF) network architecture, which provides deterministic fairness guarantees in a work-conserving manner, is selected and evaluated. Simulation studies about stateful Virtual Clock (VC) algorithm and CSGF’s sub-protocols Core-Stateless Virtual Clock (CSVC), Core-Stateless Guaranteed Throughput (CSGT) and Core-Stateless Guaranteed Fairness (CSGF) are presented. Finally, the deficiencies in fairness of CSGF are demonstrated.M.S. - Master of Scienc

Lightweight Routing With Dynamic Interests In Wireless Sensor And Actor Networks

Wireless sensor and actor networks (WSANs) have been increasingly popular for environmental monitoring applications in the last decade. While the deployment of sensor nodes enables a fine granularity of data collection, resource-rich actor nodes provide further evaluation of the information and reaction. Quality of service (QoS) and routing solutions for WSANs are challenging compared to traditional networks because of the limited node resources. WSANs also have different QoS requirements than wireless sensor networks (WSNs) since actors and sensor nodes have distinct resource constraints. In this paper, we present, LRP-QS, a lightweight routing protocol with dynamic interests and QoS support for WSANs. LRP-QS provides QoS by differentiating the rates among different types of interests with dynamic packet tagging at sensor nodes and per flow management at actor nodes. The interests, which define the types of events to observe, are distributed in the network. The weights of the interests are determined dynamically by using a nonsensitive ranking algorithm depending on the variation in the observed values of data collected in response to interests. Our simulation studies show that the proposed protocol provides a higher packet delivery ratio and a lower memory consumption than the existing state of the art protocols. © 2013 Elsevier B.V. All rights reserved

Apawsan: Actor Positioning For Aerial Wireless Sensor And Actor Networks

The node mobility is a natural element of many wireless sensor and actor network (WSAN) applications. Recent advances in the development of small unmanned aerial vehicles (UAVs) with built in sensors made it possible to deploy aerial sensor and actor networks. An aerial network composed of small UAVs enables high quality observation for events while reducing the number of personnel and the risk for the operators. In order to have an effective data collection, the positioning of actors plays a critical role in aerial WSANs. In this paper we propose an actor positioning strategy for aerial WSANs considering the scenario of toxic plume observation after a volcanic eruption, which is one of the emerging applications of aerial UAV networks. Measuring the composition of volcanic plumes allows the computation of volcanogenic fluxes and provides insights into volatile degassing mechanisms. The actors in the proposed approach use a lightweight and distributed algorithm to form a self organizing network around the central UAV, which has the role of the sink in the WSAN. Our algorithm makes use of the Valence Shell Electron Pair (VSEPR) theory of chemistry, which is based on the correlation between molecular geometry and the number of atoms in a molecule. The performance of the proposed practical positioning algorithm is presented through extensive simulations. © 2011 IEEE

Lightweight Routing With Qos Support In Wireless Sensor And Actor Networks

Wireless sensor and actor networks (WSANs) can be used for monitoring physical environments and acting according to the observations. In order to differentiate the actions based on the sensed information, WSANs comprise of various applications with different quality of service (QoS) requirements. QoS solutions for WSANs are challenging compared to traditional networks because of the limited resource capabilities of sensor nodes. In terms of QoS requirements, WSANs also differ from WSNs since actors and sensors have distinct resource constraints. In this paper we present LRP-QS, lightweight routing protocol with QoS support for WSANs. Our protocol provides QoS by differentiating the rates among different types of applications with dynamic packet tagging at the sensor nodes and per flow management at the actor nodes. Through extensive simulations we observe a greater packet delivery ratio and a better memory consumption rate in comparison with the related mechanisms. ©2010 IEEE

Towards A Comprehensive Simulator For Public Speaking Anxiety Treatment

Public speaking anxiety (PSA) is often cited as the most common social phobia. Virtual reality enables us to overcome PSA with life-like scenarios. This paper first reviews the state-of-the-art in virtual environments as an emerging treatment for public speaking anxiety and presents a comprehensive Virtual Environment (VE). In most of the studies there is a lack in the inclusion of physical and vocal cues. Physical and vocal cues generated by the audience are crucial contributors to PSA. We design a virtual auditorium with an audience exhibiting these physical and vocal cues; a comprehensive VE, helping overcome PSA. Additionally, participants are subjected to the three phases of speech: Anticipation, Performance and Recovery [Cornwell et al. in Biol Psychiatry 59(7):664–666, 2006 1]. The resulting simulator can then be used for training and eventual treatment of PSA in addition to being used as a tool for identifying cues to which speakers are more sensitive to

A Mobility Model Of Theme Park Visitors

Realistic human mobility modeling is critical for accurate performance evaluation of mobile wireless networks. Movements of visitors in theme parks affect the performance of systems which are designed for various purposes including urban sensing and crowd management. Previously proposed human mobility models are mostly generic while some of them focus on daily movements of people in urban areas. Theme parks, however, have unique characteristics in terms of very limited use of vehicles, crowd\u27s social behavior, and attractions. Human mobility is strongly tied to the locations of attractions and is synchronized with major entertainment events. Hence, realistic human mobility models must be developed with the specific scenario in mind. In this paper, we present a novel model for human mobility in theme parks. In our model, the nondeterminism of movement decisions of visitors is combined with deterministic behavior of attractions in a theme park. The attractions are categorized as rides, restaurants, and live shows. The time spent at these attractions are computed using queueing-theoretic models. The realism of the model is evaluated through extensive simulations and compared with the mobility models SLAW, RWP and the GPS traces of theme park visitors. The results show that our proposed model provides a better match to the real-world data compared to the existing models

Actor Positioning Based On Molecular Geometry In Aerial Sensor Networks

Advances in unmanned aerial vehicle (UAV) technology and wireless sensor and actor networks (WSAN) made it possible to equip small UAVs with sensors and deploy aerial sensor and actor networks. Aerial sensor networks enable high quality observation of events while reducing the number of requirements. Positioning of UAVs with actor nodes is critical in these systems for effective data collection. In this paper we propose an actor positioning strategy for aerial WSANs considering the scenario of toxic plume observation after a volcanic eruption. The positioning algorithm utilizes the Valence Shell Electron Pair Repulsion (VSEPR) theory of chemistry, which is based on the correlation between molecular geometry and the number of atoms in a molecule. The limitations of the basic VSEPR theory are eliminated by extending the approach for multiple central data collectors. The simulations show that the proposed system provides high connectivity and coverage for the aerial sensor network. © 2012 IEEE

Molecular Geometry Inspired Positioning For Aerial Networks

The advances in unmanned aerial vehicle (UAV) and wireless sensor technology made it possible to deploy aerial networks and to collect information in three dimensional (3D) space. These aerial networks enable high quality observation of events as multiple UAVs coordinate and communicate for data collection. The positioning of UAVs in aerial networks is critical for effective coverage of the environment and data collection. UAV systems have their characteristic constraints for node positioning such as dynamic topology changes or heterogeneous network structure. The positioning methods for two dimensional (2D) scenarios cannot be used for aerial networks since these approaches become NP-hard in 3D space. In this paper, we propose a node positioning strategy for UAV networks. We propose a wireless sensor and actor network structure according to different capabilities of the nodes in the network. The positioning algorithm utilizes the Valence Shell Electron Pair Repulsion (VSEPR) theory of chemistry, which is based on the correlation between molecular geometry and the number of atoms in a molecule. By using the rules of VSEPR theory, the actor nodes in the proposed approach use a lightweight and distributed algorithm to form a self organizing network around a central UAV, which has the role of the sink. The limitations of the basic VSEPR theory are eliminated by extending the approach for multiple central data collectors. The simulation results demonstrate that the proposed system provides high connectivity and coverage for the aerial sensor and actor network

Sofrop: Self-Organizing And Fair Routing Protocol For Wireless Networks With Mobile Sensors And Stationary Actors

Wireless sensor and actor networks (WSAN) have become increasingly popular in recent years. The cooperative operation between sensor and actor nodes results in a major advantage against pure sensor networks and extends the range of possible application scenarios. One emerging application is the Amazon scenario in which stationary actors are deployed at accessible points in a thick forest structure and sensor nodes are thrown in a river flowing through the forest to gather observations from unreachable areas of the forest. This unprecedented and unique setting exposes two important challenges: (a) the dynamics of the river forms a continuously varying topology of sensor nodes requiring a highly adaptive network organization and (b) the inherent features of sensor and actor nodes, combined with rapid changes in the link structure of the network require efficient bandwidth utilization and data transmission. In this paper, we address these challenges by introducing SOFROP, a novel self-organizing and fair routing protocol for WSANs. The extensive simulations that are carried out for evaluation point out two highlights of SOFROP. These are the lightweight and efficient routing that is optimized for fairness and the locally acting adaptive overlay network formation. © 2010 IEEE

Local Positioning For Environmental Monitoring In Wireless Sensor And Actor Networks

Location estimation of sensor nodes is an essential part of most applications for wireless sensor and actor networks (WSAN). The ambiguous location information often makes the collected data useless in these applications. Environmental monitoring in particular, relies on an accurate position estimation in order to process or evaluate the collected data. In this paper, we present a novel and scalable approach for positioning of mobile sensor nodes with the goal of monitoring the Amazon river. The actors in the scenario are stationary and positioned at reachable spots on the land alongside the river whereas sensor nodes are thrown into the river to collect data such as water temperature, depth and geographical features. The actors are not equipped with positioning adaptors and they are only aware of their distances from the other actors. The sensor nodes collect data and forward it to the actors. While floating in the river, sensor nodes are often multiple hops away from the actor nodes, which makes it challenging to apply traditional positioning techniques. Through extensive simulations, we show that the positioning of the nodes is feasible using a multi-hop approach with local information exchange only. © 2010 IEEE