1,026 research outputs found
Allocation of control and data channels for Large-Scale Wireless Sensor Networks
Both IEEE 802.15.4 and 802.15.4a standards allow for dynamic channel
allocation and use of multiple channels available at their physical layers but
its MAC protocols are designed only for single channel. Also, sensor's
transceivers such as CC2420 provide multiple channels and as shown in [1], [2]
and [3] channel switch latency of CC2420 transceiver is just about 200s.
In order to enhance both energy efficiency and to shorten end to end delay, we
propose, in this report, a spectrum-efficient frequency allocation schemes that
are able to statically assign control channels and dynamically reuse data
channels for Personal Area Networks (PANs) inside a Large-Scale WSN based on
UWB technology
Recommended from our members
Application priority framework for fixed mobile converged communication networks
This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The current prospects in wired and wireless access networks, it is becoming increasingly important to address potential convergence in order to offer integrated broadband services. These systems will need to offer higher data transmission capacities and long battery life, which is the catalyst for an everincreasing variety of air interface technologies targeting local area to wide area connectivity. Current integrated industrial networks do not offer application aware context delivery and enhanced services for optimised networks. Application aware services provide value-added functionality to business applications by capturing, integrating, and consolidating intelligence about users and their endpoint devices from various points in the network. This thesis mainly intends to resolve the issues related to ubiquitous application aware service, fair allocation of radio access, reduced energy consumption and improved capacity. A technique that measures and evaluates the data rate demand to reduce application response time and queuing delay for multi radio interfaces is proposed. The technique overcomes the challenges of network integration, requiring no user intervention, saving battery life and selecting the radio access connection for the application requested by the end user. This study is split in two parts. The first contribution identifies some constraints of the services towards the application layer in terms of e.g. data rate and signal strength. The objectives are achieved by application controlled handover (ACH) mechanism in order to maintain acceptable data rate for real-time application services. It also looks into the impact of the radio link on the application and identifies elements and parameters like wireless link quality and handover that will influence the application type. It also identifies some enhanced traditional mechanisms such as distance controlled multihop and mesh topology required in order to support energy efficient multimedia applications. The second contribution unfolds an intelligent application priority assignment mechanism (IAPAM) for medical applications using wireless sensor networks. IAPAM proposes and evaluates a technique based on prioritising multiple virtual queues for the critical nature of medical data to improve instant transmission. Various mobility patterns (directed, controlled and random waypoint) has been investigated and compared by simulating IAPAM enabled mobile BWSN. The following topics have been studied, modelled, simulated and discussed in this thesis: 1. Application Controlled Handover (ACH) for multi radios over fibre 2. Power Controlled Scheme for mesh multi radios over fibre using ACH 3. IAPAM for Biomedical Wireless Sensor Networks (BWSN) and impact of mobility over IAPAM enabled BWSN. Extensive simulation studies are performed to analyze and to evaluate the proposed techniques. Simulation results demonstrate significant improvements in multi radios over fibre performance in terms of application response delay and power consumption by upto 75% and 15 % respectively, reduction in traffic loss by upto 53% and reduction in delay for real time application by more than 25% in some cases
Physical Layer Simulation Study for the Co-existence of WLAN Standards
Interference is a prime factor that limits the performance of devices within the 2.4 GHz ISM Band. Due to the ISM Band being unlicensed and free to all users, there is an abundance of devices within this frequency range. The three most prominent of such devices used for data communication consist of Bluetooth, Wifi, and Zigbee. In order to understand whether these three protocols can co-exist with each other, a physical layer system model will be developed for each protocol. These systems models will be combined and their interaction with each other examined to determine the effects of the interference under different channel conditions. The channel models will consist of general AWGN and Rayleigh fading channels, along with a site-specific case involving both Ricean and Rayleigh fading
Design and evaluation of wireless dense networks : application to in-flight entertainment systems
Le rĂ©seau sans fil est l'un des domaines de rĂ©seautage les plus prometteurs avec des caractĂ©ristiques uniques qui peuvent fournir la connectivitĂ© dans les situations oĂč il est difficile d'utiliser un rĂ©seau filaire, ou lorsque la mobilitĂ© des nĆuds est nĂ©cessaire. Cependant, le milieu de travail impose gĂ©nĂ©ralement diverses contraintes, oĂč les appareils sans fil font face Ă diffĂ©rents dĂ©fis lors du partage des moyens de communication. De plus, le problĂšme s'aggrave avec l'augmentation du nombre de nĆuds. DiffĂ©rentes solutions ont Ă©tĂ© introduites pour faire face aux rĂ©seaux trĂšs denses. D'autre part, un nĆud avec une densitĂ© trĂšs faible peut crĂ©er un problĂšme de connectivitĂ© et peut conduire Ă l'optension de nĆuds isolĂ©s et non connectes au rĂ©seau. La densitĂ© d'un rĂ©seau est dĂ©finit en fonction du nombre de nĆuds voisins directs au sein de la portĂ©e de transmission du nĆud. Cependant, nous croyons que ces mĂ©triques ne sont pas suffisants et nous proposons une nouvelle mesure qui considĂšre le nombre de voisins directs et la performance du rĂ©seau. Ainsi, la rĂ©ponse du rĂ©seau, respectant l'augmentation du nombre de nĆuds, est considĂ©rĂ©e lors du choix du niveau de la densitĂ©. Nous avons dĂ©fini deux termes: l'auto-organisation et l'auto-configuration, qui sont gĂ©nĂ©ralement utilisĂ©s de façon interchangeable dans la littĂ©rature en mettant en relief la diffĂ©rence entre eux. Nous estimons qu'une dĂ©finition claire de la terminologie peut Ă©liminer beaucoup d'ambiguĂŻtĂ© et aider Ă prĂ©senter les concepts de recherche plus clairement. Certaines applications, telles que Ies systĂšmes "In-Flight Entertainment (IFE)" qui se trouvent Ă l'intĂ©rieur des cabines d'avions, peuveut ĂȘtre considĂ©rĂ©es comme des systĂšmes sans fil de haute densitĂ©, mĂȘme si peu de nĆuds sont relativement prĂ©sents. Pour rĂ©soudre ce problĂšme, nous proposons une architecture hĂ©tĂ©rogĂšne de diffĂ©rentes technologies Ă fin de surmonter les contraintes spĂ©cifiques de l'intĂ©rieur de la cabine. Chaque technologie vise Ă rĂ©soudre une partie du problĂšme. Nous avons rĂ©alisĂ© diverses expĂ©rimentations et simulations pour montrer la faisabilitĂ© de l'architecture proposĂ©e. Nous avons introduit un nouveau protocole d'auto-organisation qui utilise des antennes intelligentes pour aider certains composants du systĂšme IFE; Ă savoir les unitĂ©s d'affichage et leurs systĂšmes de commande, Ă s'identifier les uns les autres sans aucune configuration prĂ©liminaire. Le protocole a Ă©tĂ© conçu et vĂ©rifiĂ© en utilisant le langage UML, puis, un module de NS2 a Ă©tĂ© crĂ©Ă© pour tester les diffĂ©rents scĂ©narios.Wireless networking is one of the most challenging networking domains with unique features that can provide connectivity in situations where it is difficult to use wired networking, or when ! node mobility is required. However, the working environment us! ually im poses various constrains, where wireless devices face various challenges when sharing the communication media. Furthermore, the problem becomes worse when the number of nodes increase. Different solutions were introduced to cope with highly dense networks. On the other hand, a very low density can create a poor connectivity problem and may lead to have isolated nodes with no connection to the network. It is common to define network density according to the number of direct neighboring nodes within the node transmission range. However, we believe that such metric is not enough. Thus, we propose a new metric that encompasses the number of direct neighbors and the network performance. In this way, the network response, due to the increasing number of nodes, is considered when deciding the density level. Moreover, we defined two terms, self-organization and self-configuration, which are usually used interchangeably in the literature through highlighting the difference ! between them. We believe that having a clear definition for terminology can eliminate a lot of ambiguity and help to present the research concepts more clearly. Some applications, such as In-Flight Entertainment (IFE) systems inside the aircraft cabin, can be considered as wirelessly high dense even if relatively few nodes are present. To solve this problem, we propose a heterogeneous architecture of different technologies to overcome the inherited constrains inside the cabin. Each technology aims at solving a part of the problem. We held various experimentation and simulations to show the feasibility of the proposed architecture
Wireless Technologies for IoT in Smart Cities
[EN] As cities continue to grow, numerous initiatives for Smart Cities are being conducted. The
concept of Smart City encompasses several concepts being governance, economy,
management, infrastructure, technology and people. This means that a Smart City can have
different communication needs. Wireless technologies such as WiFi, ZigBee, Bluetooth,
WiMax, 4G or LTE (Long Term Evolution) have presented themselves as solutions to the
communication needs of Smart City initiatives. However, as most of them employ unlicensed
bands, interference and coexistence problems are increasing. In this paper, the wireless
technologies available nowadays for IoT (Internet of Things) in Smart Cities are presented.
Our contribution is a review of wireless technologies, their comparison and the problems that
difficult coexistence among them. In order to do so, the characteristics and adequacy of
wireless technologies to each domain are considered. The problems derived of over-crowded
unlicensed spectrum and coexistence difficulties among each technology are discussed as
well. Finally, power consumption concerns are addressed.GarcĂa-GarcĂa, L.; Jimenez, JM.; Abdullah, MTA.; Lloret, J. (2018). Wireless Technologies for IoT in Smart Cities. Network Protocols and Algorithms. 10(1):23-64. doi:10.5296/npa.v10i1.12798S236410
Dual protocol performance using WiFi and ZigBee for industrial WLAN
The purpose of this thesis is to study the performance of a WNCS based on utilizing IEEE 802.15.4 and IEEE 802.11 in meeting industrial requirements as well as the extent of improvement on the network level in terms of latency and interference tolerance when using the two different protocols, namely WiFi and ZigBee, in parallel. The study evaluates the optimum performance of WNCS that utilizes only IEEE 802.15.4 protocol (which ZigBee is based on) without modifications as an alternative that is low cost and low power compared to other wireless technologies. The study also evaluates the optimum performance of WNCS that utilizes only the IEEE 802.11 protocol (WiFi) without modifications as a high bit network. OMNeT++ simulations are used to measure the end-to-end delay and packet loss from the sensors to the controller and from the controller to the actuators. It is demonstrated that the measured delay of the proposed WNCS including all types of transmission, encapsulation, de-capsulation, queuing and propagation, meet real-time control network requirements while guaranteeing correct packet reception with no packet loss. Moreover, it is shown that the demonstrated performance of the proposed WNCS operating redundantly on both networks in parallel is significantly superior to a WNCS operating on either a totally wireless ZigBee or WiFi network individually in terms of measured delay and interference tolerance. This proposed WNCS demonstrates the combined advantages of both the IEEE 802.15.4 protocol (which ZigBee is based on) without modifications being low cost and low power compared to other wireless technologies as well the advantages of the IEEE 802.11 protocol (WiFi) being increased bit rate and higher immunity to interference. All results presented in this study were based on a 95% confidence analysis
- âŠ