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Network Functions Virtualization (NFV) is a recent industrial trend which gains a lot of attention from telecom operators and vendors. The NFV concept delivers network services using commercial off-the-shelf hardware and IT virtualization technologies, thus virtualizing entire classes of network node functions. Traditional and recent data-center architectures are mostly built and optimized for data...
Software defined networking[1][9] has brought a rapid change in networking industry by providing programma-bility and abstraction. it also enables centralization of control in infrastructure. In this paper, we describe the results of our experiment to determine the performance of SDN by simulating Open vSwitch under conditions of congestion. We did experiments on MININET by creating four compute nodes...
In a majority of European countries a digital trunking TETRA system is used for Public Safety communication. This system offer voice communication and narrowband data services only. Since the introduction of first LTE commercial networks, LTE is rapidly gaining momentum within the Public Safety industry as well. Therefore it is important to verify the immunity of the system, originally designed for...
One of the most popular approaches to improving bandwidth efficiency is the use of signals with inter-symbol interference (ISI). In this paper bandwidth-efficient partial response signals (PRS) are analyzed in combinations with 4-QAM, 8-QAM and 16-QAM signal constellations and recursive systematic convolutional codes. We simulated transmission of encoded data through AWGN channel using the optimal...
Spectrum sensing is one of the core functionalities of a true cognitive radio (CR) that supports operation over a broad range of frequencies and can autonomously adapt transmission parameters to the operating environment. There are several types of hardware ranging from sophisticated (i.e. Nutaq Radio420X FPGA mezzanine card) to low cost (i.e. WiSpy) that can be used to experiment with spectrum sensing...
The widespread use of mobile devices such as smartphones and tablets is flanked by an ever increasing supply of mobile applications. Along with this trend, expectations and requirements of users rise as well. For example, users do not want to compromise on comfortable daily routines as available on desktop computers. However, an intrinsic characteristic of mobile devices is their limited availability...
Software-Defined Networking (SDN) has recently gained significant momentum. However, before any large scale deployments, it is important to understand security issues arising from this new technology. This paper discusses two types of Denial-of-Service (DoS) attacks specific to OpenFlow SDN networks. We emulate them on Mininet and provide an analysis on the effect of these attacks. We find that the...
A novel 2-tier integrated communication system is proposed to address the issue of unavailable Road Side Unit (RSU) in Intelligent Transport System (ITS). Compared to some other solutions proposed in the previous research works, which mostly focus on improving the system performance by adjusting parameters of vehicular ad-hoc network among vehicles, the proposed 2-tier communication network, called...
Thales has a long heritage in high power C-Band Travelling Wave Tubes for space application. This paper described a new generation of C-Band TWT designed for a broadband application in space: higher output power and wider instantaneous bandwidth a new developed high power gun has improved the beam focus ability and the laminar beam behaviour with a well optimized helix and collector design delivering...
Motivated in part by the success of WiFi, there has been much interest in opening up new “prime” bands of spectrum for unlicensed use. Such bands can lower the cost for new wireless service providers to enter a market. The increased competition could in turn improve economic welfare. However, the openness of such spectrum can also lead to it becoming over congested, which in turn could deter investment...
Software-Defined Networking (SDN) has greatly enriched the flexibility of network management. It introduces a central controller to take over most network functions that otherwise reside in distributed forwarding devices. Such a centralized design, however, tends to make control channel a bottleneck due to bandwidth fatigue. Existing work saves control channel bandwidth at the expense of losing visibility...
Fair sharing of bandwidth among tenants in datacenters is important to guarantee prompt execution while providing isolation between different jobs. Existing bandwidth allocation methods lack a concept of a task reflecting the dependency between allocations on links. Moreover, existing approaches do not consider the tenants to be smart individuals and lack understanding of a threat that strategic players...
Time of arrival is a commonly used mechanism for geolocation. In many environments, multipath propagation of RF signals limits accuracy. Wide bandwidths reduce the impact of multipath propagation, but frequently results in interference from other devices. When the bandwidth is assembled from several measured sub-bands, there is an additional difficulty of a random phase offset between bands. In this...
This work presents a novel on-the-fly void filling scheme for Long-Reach EPON called Size Controlled Batch Void Filling (SCBVF). SCBVF aims at reducing the time between consecutive bandwidth grants (attendance time) and hence reducing the average delay for delay-sensitive traffic.
This paper deals with the performance evaluation of image segmentation. The goal of this work is to show some techniques that enable the comparison of different segmentation results. We first present a visualization method that facilitates the visual evaluation of a segmentation result. Next, we focus on unsupervised evaluation criteria that do not take into account any a priori knowledge to quantify...
In this paper, a compact Inverted-F Antenna (IFA) is proposed for penta-band (GSM850/900/DCS/PCS/WCDMA bands) operation. The proposed IFA is designed with a compact size of 28.75 mm × 16.7 mm and printed on one layer substrate for the simple design and low-profile configuration, and cost-effectiveness. The IFA is modified by dividing the radiating strip in order to realize a multi-band operation....
This paper presents a peer-to-peer (P2P) framework for the deployment of live video streaming applications over P2P overlay networks. The proposed framework provides support for flash-crowds, decentralizes decision making and makes use of network coding to reduce bandwidth consumption. We present the framework and the simulation results that demonstrate the framework's effectiveness.
WiFi is currently the most widely used communication standard over wireless LAN . Facing the trend that broad band and networking quality are emphasized, the IETF SIGTRAN working group and IEEE 802.11standards working groups proposed a new-generation communication protocol, stream control transmission protocol (SCTP) and wireless LAN communication standard, IEEE 802.11ac/VHT for transport layer and...
In order to realize practical dynamic spectrum access (DSA), implementing spectrum sensing with reasonably low cost is very challenging due to the required detection accuracy and quickness. For this issue, we have introduced an extended DSA, smart spectrum access (SSA), where any useful information in terms of spectrum utilization, such as statistics regarding spectrum utilization, is used not only...
This paper studies the problem of joint allocation of transmission power and bandwidth in cooperative networks. The goal is to minimize transmission energy consumption in a network with M coordinated transmission points (CTPs) under respective data rate constraints of N mobile terminals (MTs). We propose a joint power and bandwidth allocation scheme for downlink data transmission based on mathematical...
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