Search results for "Computer network"
showing 10 items of 1634 documents
A feasibility analysis on the use of ultrasonic multihop communications for E-health applications
2017
Rise in population aging as well as diffusion of chronic diseases and health consciousness require constant monitoring of health conditions but also lead to increasing costs for the governments. Body Area Networks represent the next frontier in health care and are envisaged as the natural choice to provide detailed and updated information on health status to prevent health risks and diseases. However if, on the one hand, a large research effort has been devoted so far to the investigation of BAN communications on and around the body, on the other hand intra-BAN communications are still a scarcely explored area because of the difficulties and risks in successfully propagating signals inside …
Location-Aware Mobile Intrusion Detection with Enhanced Privacy in a 5G Context
2010
Published version of an article from the journal: Wireless Personal Communications. The original publication is available at Spingerlink. http://dx.doi.org/10.1007/s11277-010-0069-6 The paper proposes a location-aware mobile Intrusion Prevention System (mIPS) architecture with enhanced privacy that is integrated in Managed Security Service (MSS). The solution is envisaged in a future fifth generation telecommunications (5G) context with increased but varying bandwidth, a virtualised execution environment and infrastructure that allows threads, processes, virtual machines and storage to be migrated to cloud computing services on demand, to dynamically scale performance and save power. 5G mob…
Cooperative Medium Access Control in Wireless Networks: The Two-Hop Case
2009
Cooperative communication has been recently proposed as a powerful means to improve network performance in wireless networks. However, most existing work focuses solely on one-hop source-destination cooperation. In this paper, we propose a novel cooperative MAC mechanism that is specially designed for two-hop cooperation communications where the source node and the destination node cannot hear each other directly. In this case, cooperative communication is operated in a two-hop manner and transmit-diversity is achieved by the reception of the same data packet forwarded through multiple relays towards a single destination. The proposed scheme employs an efficient relay selection algorithm to…
On the Benefits of Random Linear Coding for Unicast Applications in Disruption Tolerant Networks
2006
In this paper, we investigate the benefits of using a form of network coding known as Random Linear Coding (RLC) for unicast communications in a mobile Disruption Tolerant Network (DTN) under epidemic routing. Under RLC, DTN nodes store and then forward random linear combinations of packets as they encounter other DTN nodes. We first consider the case where there is a single block of packets propagating in the network and then consider the case where blocks of K packets arrive according to a Poisson arrival process. Our performance metric of interest is the delay until the last packet in a block is delivered. We show that for the single block case, when bandwidth is constrained, applying RL…
An optimal energy efficient cooperative retransmission MAC scheme in wireless networks
2011
While the benefits of cooperative diversity have been well studied in the literature, cooperative MAC protocol design has also attracted much attention recently. In the single-relay Cooperative Automatic Repeat reQuest (C-ARQ) protocol, the best relay node is selected in a distributed manner by relays using different backoff time before packet retransmission. However, this relay selection scheme does not work efficiently in a dense network scenario, due to possible high collision probability among different contending relays. In this paper, we propose an optimized relay selection scheme to maximize system energy efficiency by reducing collision probability. The energy efficiency performance…
FALCON - joint fair airtime allocation and rate control for DASH video streaming in software defined wireless networks
2020
Software Defined Wireless Networks offer an opportunity to enhance the performance of specific services by applying centralized mechanisms which make use of a global view of the network resources. This paper presents FALCON, a novel solution that jointly optimizes fair airtime allocation and rate recommendations for Server and Network Assisted DASH video streaming, providing proportional fairness among the clients. Since this problem is NP-hard, FALCON introduces a novel heuristic algorithm that is proved to achieve almost optimal results in a practical amount of time. The performance of FALCON is evaluated when used in conjunction with three referent Adaptive Bit Rate strategies (PANDA, BO…
A study on the statistical properties of double hoyt fading channels
2009
This paper deals with a study on the statistical properties of narrowband amplify-and-forward relay fading channels for Hoyt multipath propagation environments. We consider the basic radio link topology, where only one fixed relay station is used for the amplification. In this case, the envelope of the signal received over the overall multipath channel is modeled by the so-called double Hoyt fading process. Considering this multipath propagation channel model, analytical expressions for the first and second order statistics are provided. Specifically, the mean value, variance, probability density function (PDF), level-crossing rate (LCR), and average duration of fades (ADF) of double Hoyt p…
HSDPA Link Adaptation Improvement Based on Node-B CQI Processing
2007
In this paper HSDPA link adaptation (LA) based on Channel Quality Indicator (CQI) reports is optimised. A pre-processing of the last received CQI reports is done before the execution of the LA algorithm in the Node-B in order to obtain more profitable channel quality estimations and hence improve the LA performance. Different types of processing techniques are presented and assessed, considering from the simplest sample averaging to some more elaborated predictive algorithms. Results demonstrate that a non negligible enhancement in the LA performance can be obtained if medium and high speed users are considered.
Evaluation of user experience goal fulfillment
2014
In this paper, the results of a user experience (UX) goal evaluation study are reported. The study was carried out as a part of a research and development project of a novel remote operator station (ROS) for container gantry crane operation in port yards. The objectives of the study were both to compare the UXs of two different user interface concepts and to give feedback on how well the UX goals experience of safe operation, sense of control, and feeling of presence are fulfilled with the developed ROS prototype. According to the results, the experience of safe operation and feeling of presence were not supported with the current version of the system. However, there was much better suppor…
ZigBee networks performance under WLAN 802.11b/g interference
2009
ZigBee is a standard protocol suite for low rate wireless personal area networks (LR-WPANs) and has been widely utilized in various fields. Since both ZigBee and WLAN (802.11b/g) operate in the 2.4GHz unlicensed industrial scientific medical (ISM) frequency band, mutual interference is likely to exist and cause signal degradation. In this paper, an interference analysis model is suggested to obtain an estimate of Packet Error Rate (PER) of a ZigBee network. A ZigBee evaluation kit, AVR RZ200, was implemented for measurement of Packet Loss Ratio (PLR). The measured PLR matches the estimated PER, with varied distances and different center frequency offsets of different channels.