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Due to the limited coverage range of access points (APs) and the mobility of stations (STAs), handoff occurs frequently in IEEE 802.11 wireless local area network (WLAN). However, traditional handoff mechanisms employed at STAs have inherent defects which make it hard to realize seamless handoff, it is a challenging issue for supporting seamless handoff service in WLAN. Extensions to Software Defined...
The emerging 5G networks are intended to enable new feedback control applications, run over multiple wireless interfaces. 5G wireless technologies then need to match the state-of-the- art wired network performance, experienced by present commercial feedback control systems. Fibre-optic circuit switched communication is characterized by constant and very low loop delays, uniform and very high sampling...
The explosion of traffic demands within data centers accentuates the conventional infrastructures ossification. Unfortunately, the traditional tree based architectures struggle to resist and suffer from congestion and wiring complexity which deeply deteriorate the network performance. In aim to address the QoS degradation, we put forward a Hybrid Data Center Network (HDCN) architecture based on CISCO's...
For high spectrum usage, some independent wireless communication systems should share multi-channel environment. An offloading effect over multi-channel makes system throughput enhanced. A multi-channel access based on channel activities of other systems, which are channel occupancy ratio (COR), is important. The estimation of COR needs a traceability to the transition of COR. In software define radio,...
Recent studies show that the wireless technology could resolve the oversubscription issue in wireless data center networks (WDCNs). However, these works only focus on transmitting traffic flows at the top-of-rack (ToR) switch. In this paper, we propose a deadline-aware rate control scheme (DRCS) that detects the network congestion situation by considering the flow size, deadline, and the number of...
Previous attempts in addressing Access Point (AP) association at overlapping zone of IEEE 802.11 networks have shown some issues. They work passively and estimate load from different network metrics such as frame delay, packet loss, number of users etc. that may not always true. Further the user behaviour is selfish i.e. illegitimate user consume high network resources. This adversely affect existing...
Thanks to their flexibility and their simplicity of installation, Wireless Mesh Networks (WMNs) allow a low cost deployment of network infrastructure. They can be used to extend wired networks coverage allowing connectivity anytime and anywhere. However, WMNs may suffer from drastic performance degradation (e.g., increased packet loss ratio and delay) because of interferences and congestion. Generally,...
The Demand for wireless lighting is expected to increase in the residential environment, as well as building, gym, factories in these days. A large number of wireless lighting is controlled by a controller in these environments. We proposed an advanced touch-link algorithm to reduce delay time that occurs when connecting a lot of wireless lightings. The ZigBee switch and 128 ZigBee lightings are implemented...
A 60 GHz wireless communication system has been proposed as a replacement for data cables in a data-center cabinet in order to reduce the significant cooling energy costs. This paper investigates the feasibility of placing adaptive absorber-reflector regions on the sides of a cabinet as a static channel fading counter-measure and also to optimize performance for a particular server. As a result of...
Recently, buttery-powered portable devices, which can use wireless LAN (WLAN), such as smart phones and tablet computers, are increasing. However, these devices consume more energy when using WLAN interfaces, and the battery lifetime is shorten. In order to reduce the power consumption of wireless stations, IEEE 802.11 specifies PSM (Power Saving Mode). However, PSM cannot save the energy optimally...
With the technological progress of wireless technologies, an alternative avionic communication architecture based on wireless connectivity has been proposed to cope with the emerging avionics issues, i.e., reducing weight and costs. The performance analysis of such a proposal is conducted herein to quantify the impact of unreliable wireless links on transmission delays, and the efficiency of retransmission-based...
Packet loss occurs when one or more packets across various computer network drop before reaching destination. The era of wireless communications has brought the evaluation of distributed mobile computing and communications anytime anywhere to a reality. This paper presents an efficient survey of packet loss probability of various wireless sensor networks. It also describes packet loss overview and...
This paper proposes a novel architecture for a hierarchical Wireless Networked Control System (WNCS). It consists of three cascaded workcells each containing 30 sensors, 30 actuators and one controller. The wireless communication protocol used is IEEE 802.11g with multicasting. The hierarchy of the system is such that the lowest level is that of the sensors and actuators, the intermediate level is...
In the half-duplex single relay selection network, comprised of a source, M half-duplex relays, and a destination, only one relay is active at any given time, i.e., only one relay receives or transmits, and the other relays are inactive, i.e., they do not receive or transmit. The capacity of this network, when all links are affected by independent time-continuous fading and additive white Gaussian...
Data centers face problems with concerns about instability in power supply systems caused by sharp changes in load such as power consumption by servers and diversification patterns in their power consumption. We have investigated a method of switching power flows by using power semiconductors via economical 920-MHz band wireless communication to control rises and falls in power in real time as a solution...
IEEE 802.11 based wireless local area networks (WLANs) have widespread deployment in a variety of settings in recent years. To improve the utilization of the networks, the problem of user association has been studied extensively that attempts to achieve load balance among APs. To quantify the traffic load conditions, different performance metrics have been adopted. In this paper, we focus on the unsaturated...
Software Defined Networking (SDN) and OpenFlow represent the most commonly deployed approaches of the so called Programmable Networks. SDN is an emerging network architecture, which performs the subdivision of control plane and data plane and allows greater speed, greater scalability, and greater ductility in terms of routing and forwarding. OpenFlow, instead, is an SDN component that characterizes...
We consider the controller design problem for discrete-time LTI systems with state feedback, when the actuation signal is subject to switching propagation delays, due to e.g. the routing in a multi-hop communication network. Even though the systems studied here are inherently switching systems, we show that their particular structure allows for analytical understanding of the dynamics, and efficient...
Cloud datacenters are increasingly adopting virtual machines (VMs) to provide elastic cloud services, with TCP being prevalently used for congestion control. In virtualized datacenters, the delays from the hypervisor scheduler can heavily contaminate RTTs sensed by VM senders, preventing TCP from correctly learning the physical network condition. In this dissertation, my direction is to paravirtualize...
In this paper we study opportunistic spectrum access (OSA) policies in a multiuser multichannel random access setting, where users perform channel probing and switching in order to obtain better channel condition or higher instantaneous transmission quality. However, unlikely many prior works in this area, including channel probing and switching policies for a single user to exploit spectral diversity,...
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