Orhan Gemikonakli

Learn More
Mobility is one of the major issues in the performance characterization of wireless communication systems. Various approaches exist in the literature for performance evaluation of mobile systems, especially the handoff phenomenon. However, since the probability of an ongoing call being dropped due to a handoff failure and the probability of a new call being(More)
Mobility is one of the major issues in the performance characterization of wireless communication systems. Wireless communication systems encounter failures. These failures can occur because of software, hardware, human error, or a combination of these factors. The probability of an ongoing call being dropped due to a handoff failure and the probability of(More)
In recent years, there has been a huge trend towards running network intensive applications, such as Internet servers and Cloud-based service in virtual environment, where multiple virtual machines (VMs) running on the same machine share the machine's physical and network resources. In such environment, the virtual machine monitor (VMM) virtualizes the(More)
Multiprocessor system models are extensively used in modelling transaction processing systems, nodes in communication networks, and flexible machine shops with groups of machines. Such systems clearly, are prone to break-downs. Even if cover is provided with some probability c, there will be rebooting and/or reconfiguration delays to resume operation(More)
This paper presents a new way of using an aggregated RSVP tunnel mechanism in nested HMIPv6 in order to improve QoS for the Mobile Node (MN). This technique consists of two-layer Mobility Anchor Points (MAPs) named Global MAP(GMAP) and Local MAP(LMAP). The first MAP (GMAP) is placed at the gateway to the Internet and the other MAPs (LMAPs) are placed(More)
Open queuing network systems are useful in the computer industry. In this paper, a multi-node open network, with heterogeneous nodes, each node serving external as well as routed internal arrivals of jobs is considered. The nodes are prone to failures and repairs, the buffers are of finite size. An approximate performability model is developed based on an(More)
A Wireless Sensor Network (WSN) is composed of distributed sensors with limited processing capabilities and energy restrictions. These unique attributes pose new challenges amongst which prolonging the WSN lifetime is one of the most important. Challenges are often tackled by a code-and-fix process that relies on low-level hardware and software information.(More)
Multi-channel assignments are becoming the solution of choice to improve performance in single radio for wireless networks. Multi-channel allows wireless networks to assign different channels to different nodes in real-time transmission. In this paper, we propose a new approach, Multi-channel Distributed Coordinated Function (MC-DCF) which takes advantage(More)
Energy consumption of nodes is a crucial factor that constrains the networks life time for Wireless Sensor Networks (WSNs). WSNs are composed of small sensors equipped with low-power devices, and have limited battery power supply. The main concern in existing architectural and optimisation studies is to prolong the network lifetime. The lifetime of the(More)