Gurcu Oz

Performance study of a wireless mobile ad hoc network with orientation-dependent internode communication scheme

A Petri-net-based simulation model of a wireless mobile ad hoc network is developed and studied. The model covers all the fundamental aspects of behaviour of such a network and uses a novel scheme of orientation-dependent or sector-dependent internode communication, with random states of links. The proposed scheme enables representation of reliability aspects of wireless communication, such as fading effects, interferences, presence of obstacles and weather conditions in a general and rather easy way. The simulation model was implemented in terms of a class of extended Petri nets to explicitly represent parallelism of events and processes in the WLAN as a distributed system. In the simulation, the behaviour of four fundamental performance metrics - packet delivery ratio, average number of hops, relative network traffic and end-to-end delay - were investigated with varying distance of transmission and different combinations of model parameters. Copyright

A randomized contention-based load-balancing protocol for a distributed multiserver queuing system

A novel protocol for load balancing in distributed multiserver queuing systems is proposed. The protocol is based on an anonymous multicast communication in a network of servers or workers. A formal description of the protocol in terms of a state diagram is given. The complexity issues of the protocol are considered. The protocol was investigated by the use of a simulation model in terms of a class of the extended Petri nets and implemented as a prototype system on a group of computers in a LAN of Ethernet type. The results of simulation and prototype-system studies of a distributed queuing system with the proposed protocol are compared to the behavior of an ideal, centralized queuing system. Limitations and possible extensions to the protocol are outlined.

Influence of mobility models on the performance of data dissemination and routing in wireless mobile ad hoc networks

Graphical abstractDisplay Omitted Extended simulations for AODV, DSDV, and DSR routing protocols on MGM, GMM, and RPGM mobility models in addition to RWPM.Longer duration considered for simulation of routing protocols over mobility models and first 500s discarded.Results will help researchers to decide which routing protocol is better for which mobility model. Many routing protocols are proposed in the literature on mobile ad hoc networks (MANETs). Some of those protocols which have been investigated under different assumptions are unable to capture the actual characteristics of MANETs. Therefore, there is a necessity to investigate the performance of MANETs under a number of different protocols with various mobility models. This paper evaluates the performance of the single path routing protocols (AODV, DSR, and DSDV), in the presence of different network loads and differing mobility models. Our findings show that DSR routing protocol has a better performance compared to other protocols with respect to various metrics.

Experimental investigation of data transmission in wireless ad hoc networks

The paper describes implementation of an application-layer program for experimental investigation of data transmission in wireless ad hoc networks in a real-word environment. The designed multithreaded program is executed on the laptops running the Vista operating system. The program performs routing and data transmission in different ad hoc network configurations. Some important performance metrics in wireless ad hoc networks are studied with this program.

Performance evaluation of data dissemination in real-world wireless ad hoc networks

This paper presents data dissemination performance of real-world wireless ad hoc networks under different conditions. All real-world experiments are conducted in an outdoor land and carried out by laptop computers running Windows Vista operating system. An application-layer multithreaded program is used to investigate network performance. In experiments, the behavior of two fundamental performance metrics - delivery ratio, average round trip time was investigated with varying application data sizes and different combinations of network parameters.

Performance study of a wireless mobile ad hoc network with orientation-dependent inter-node communication links

A Petri-net-based simulation model of a wireless mobile ad hoc network is studied. The model includes a parameterized mobility model and a novel scheme of orientation-dependent inter-node communication links with random states. In simulation, three fundamental performance metrics — packet delivery rate, average number of hops and relative network traffic — are investigated under different combinations of model parameters.

Competition-based load balancing for distributed systems

The aim of this paper is to propose a new competition-based load balancing scheme and investigate it. The system is composed of a set of workstation clusters. The paper deals with balancing for multi-task concurrent applications, as well as for independent tasks. We developed a simulation load balancing system (LOBAS) that was used to test a competition driven load balancing algorithm. The results obtained show viability of such algorithm. The algorithm has a potential for scalability with respect to the number of tasks

Experimental Study of Pure Flooding Method for Localizing an Anycast Server in Wireless Ad Hoc Networks

This paper presents performance of a flooding based any cast mechanism for locating the nearest server from a group of contents-equivalent servers in real-world wireless ad hoc networks. Any casting can be considered as an advantageous communication paradigm for ad hoc networks where resource efficiency and robustness is of the first importance. A series of experiments are conducted in an outdoor land and carried out by laptop computers running Windows Vista operating system. An application layer any cast based multithreaded program is developed and used for investigations. In experiments, the behavior of some fundamental performance metrics: response ratio, relative network traffic, average response time and duplicate ratio, was investigated with varying number of hops between source and a group of server nodes in the network.

An Overview of Energy-Efficient Cloud Data Centres

The designers of computing systems have interested on the improvements of computing performance that are driven by the demand of consumer, business, and scientific applications. However, further growth of computing performance has started to be limited due to the increasing energy consumption of cloud data centres as a result of carbon dioxide footprints and overwhelming electricity bills. Therefore, the designers of computing systems have started to improve the energy efficiency. In this study, we present an overview of energy efficient design of cloud virtualized data centres to guide future design and development efforts.

A restricted flooding mechanism for efficient anycast server localization in MANETs

Abstract In wireless networks, reducing the number of redundant packets is one of the important mechanisms to minimize the required network bandwidth and the power consumed by network nodes. In this paper, an efficient and stateless flooding mechanism for anycast routing in wireless mobile ad hoc networks is proposed. The mechanism uses the technique of expanding ring search to decrease the related message traffic. A model of this mechanism is described. Based on this model, an extensive simulation study, together with real field experiments, has been conducted to investigate the performance of the proposed mechanism for anycast server localization. The simulation model has been developed in terms of a class of extended Petri nets that provide the possibility to conveniently represent parallelism of events and processes in the network. In simulation and real work experiments, fundamental performance metrics—response ratio, relative traffic and average response time—were investigated with varying distance of transmission and different combinations of model parameters. The obtained results show that the proposed approach to server localization in mobile ad hoc networks has good characteristics. As was demonstrated with a prototype system, the proposed routing method can be easily implemented at the application layer, without any changes at lower layers of the network protocol stack.