39 research outputs found

    Roaming Real-Time Applications - Mobility Services in IPv6 Networks

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    Emerging mobility standards within the next generation Internet Protocol, IPv6, promise to continuously operate devices roaming between IP networks. Associated with the paradigm of ubiquitous computing and communication, network technology is on the spot to deliver voice and videoconferencing as a standard internet solution. However, current roaming procedures are too slow, to remain seamless for real-time applications. Multicast mobility still waits for a convincing design. This paper investigates the temporal behaviour of mobile IPv6 with dedicated focus on topological impacts. Extending the hierarchical mobile IPv6 approach we suggest protocol improvements for a continuous handover, which may serve bidirectional multicast communication, as well. Along this line a multicast mobility concept is introduced as a service for clients and sources, as they are of dedicated importance in multipoint conferencing applications. The mechanisms introduced do not rely on assumptions of any specific multicast routing protocol in use.Comment: 15 pages, 5 figure

    TCP Performance in Heterogeneous Wireless Networks

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    The TCP protocol is used by most Internet applications today, including the recent mobile wireless terminals that use TCP for their World-Wide Web, E-mail and other traffic. The recent wireless network technologies, such as GPRS, are known to cause delay spikes in packet transfer. This causes unnecessary TCP retransmission timeouts. This dissertation proposes a mechanism, Forward RTO-Recovery (F-RTO) for detecting the unnecessary TCP retransmission timeouts and thus allow TCP to take appropriate follow-up actions. We analyze a Linux F-RTO implementation in various network scenarios and investigate different alternatives to the basic algorithm. The second part of this dissertation is focused on quickly adapting the TCP's transmission rate when the underlying link characteristics change suddenly. This can happen, for example, due to vertical hand-offs between GPRS and WLAN wireless technologies. We investigate the Quick-Start algorithm that, in collaboration with the network routers, aims to quickly probe the available bandwidth on a network path, and allow TCP's congestion control algorithms to use that information. By extensive simulations we study the different router algorithms and parameters for Quick-Start, and discuss the challenges Quick-Start faces in the current Internet. We also study the performance of Quick-Start when applied to vertical hand-offs between different wireless link technologies.Suurin osa Internet-sovelluksista kÀyttÀÀ TCP-protokollaa turvatakseen luotettavan tiedonvaihdon. TÀllaisia sovelluksia ovat esimerkiksi WWW, sÀhköposti, ja monet pikaviestiohjelmat. TCP-protokollan pÀÀpiirteet on suunniteltu 1970- ja 1980-luvulla, jolloin pÀÀtelaitteita ja sovelluksia oli huomattavasti nykyistÀ vÀhemmÀn ja yhteydet pohjautuivat kiinteiden kommunikaatiolinkkien kÀyttöön. Langattomien pÀÀtelaitteiden yleistyessÀ on huomattu, ettÀ TCP-protokollan suorituskyky ei aina ole hyvÀksyttÀvÀllÀ tasolla, koska monet sen piirteistÀ on alunperin suunniteltu erilaisessa kÀyttöympÀristössÀ. VÀitöstyö perehtyy langattoman linkin aiheuttamien vaikeasti ennustettavien viiveiden vaikutukseen TCP:n suorituskyvylle. TÀllainen kÀyttÀytyminen on ominaista esimerkiksi nykyisin laajalti matkapuhelimissa kÀytetylle GPRS-teknologialle. YllÀttÀvÀt viiveet datansiirrossa aiheuttavat TCP:n uudelleenlÀhetysajastimen tarpeettoman laukeamisen. TÀmÀ aiheuttaa useiden pakettien turhan uudelleenlÀhetyksen ja vaikeuttaa TCP:n ruuhkanvalvonta-algoritmien toimintaa. VÀitöstyössÀ ehdotetaan F-RTO -nimistÀ parannusta TCP:n uudelleenlÀhetysalgoritmeihin, joka pyrkii havaitsemaan turhat uudelleenlÀhetykset ja vÀlttÀmÀÀn edellÀ mainitut ongelmat tÀllaisissa tilanteissa. VÀitöstyö analysoi F-RTO:n suorituskykyÀ erilaisissa kommunikaatioskenaarioissa ja tutkii erilaisia variaatioita perusalgoritmiin. LisÀksi vÀitöskirjassa tutkitaan TCP:n lÀhetysnopeuden pikaista sopeuttamista vallitseville siirto-olosuhteille. Normaalisti TCP tarvitsee huomattavan ajan löytÀÀkseen oikean siirtonopeuden yhteyden alussa, mikÀli siirtolinkki on erityisen nopea ja siirtoviiveet verraten pitkiÀ. TÀmÀ on tilanne uusimmissa langattomissa kommunikaatioteknologioissa. Samankaltainen ongelma esiintyy myös, mikÀli TCP-yhteys vaihtaa kÀyttÀmÀÀnsÀ siirtoteknologiaa kesken yhteyden esimerkiksi liikkuvuuden seurauksena. TÀmÀ voi tapahtua uusimmissa pÀÀtelaitteissa, jotka tukevat useita erityyppisiÀ radioteknologioita, kuten WLAN ja GPRS. VÀitöskirjassa tutkitaan Quick-Start - nimistÀ mekanismia, joka nopeuttaa huomattavasti TCP:n sopeutumisnopeutta edellÀ mainitun kaltaisissa tilanteissa. TyössÀ tarkastellaan erilaisia algoritmeja Quick-Startin kÀyttöön ja analysoidaan simulointien avulla algoritmien toimintaa erilaisissa ympÀristöissÀ. VÀitöstyössÀ esitetyillÀ tuloksilla Internet-kommunikaation suorituskykyÀ ja kÀytettÀvyyttÀ langattomilla laitteilla voidaan parantaa huomattavasti

    Design a CPW antenna on rubber substrate for multiband applications

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    This paper presents a compact CPW monopole antenna on rubber substrate for multiband applications. The multi band applications (2.45 and 3.65 GHz) is achieved on this antenna design with better antenna performances. Specially this antenna focused on ISM band application meanwhile some of slots (S1, S2, S3) have been used and attained another frequency band at 3.65 GHz for WiMAX application. The achievement of the antenna outcomes from this design that the bandwidth of 520 MHz for first band, the second band was 76 MHz for WiMAX application and the radiation efficiency attained around 90%. Moreover, the realized gain was at 4.27 dBi which overcome the most of existing design on that field. CST microwave studio has been used for antenna simulation

    Applied Metaheuristic Computing

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    For decades, Applied Metaheuristic Computing (AMC) has been a prevailing optimization technique for tackling perplexing engineering and business problems, such as scheduling, routing, ordering, bin packing, assignment, facility layout planning, among others. This is partly because the classic exact methods are constrained with prior assumptions, and partly due to the heuristics being problem-dependent and lacking generalization. AMC, on the contrary, guides the course of low-level heuristics to search beyond the local optimality, which impairs the capability of traditional computation methods. This topic series has collected quality papers proposing cutting-edge methodology and innovative applications which drive the advances of AMC

    MediaSync: Handbook on Multimedia Synchronization

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    This book provides an approachable overview of the most recent advances in the fascinating field of media synchronization (mediasync), gathering contributions from the most representative and influential experts. Understanding the challenges of this field in the current multi-sensory, multi-device, and multi-protocol world is not an easy task. The book revisits the foundations of mediasync, including theoretical frameworks and models, highlights ongoing research efforts, like hybrid broadband broadcast (HBB) delivery and users' perception modeling (i.e., Quality of Experience or QoE), and paves the way for the future (e.g., towards the deployment of multi-sensory and ultra-realistic experiences). Although many advances around mediasync have been devised and deployed, this area of research is getting renewed attention to overcome remaining challenges in the next-generation (heterogeneous and ubiquitous) media ecosystem. Given the significant advances in this research area, its current relevance and the multiple disciplines it involves, the availability of a reference book on mediasync becomes necessary. This book fills the gap in this context. In particular, it addresses key aspects and reviews the most relevant contributions within the mediasync research space, from different perspectives. Mediasync: Handbook on Multimedia Synchronization is the perfect companion for scholars and practitioners that want to acquire strong knowledge about this research area, and also approach the challenges behind ensuring the best mediated experiences, by providing the adequate synchronization between the media elements that constitute these experiences

    Applied Methuerstic computing

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    For decades, Applied Metaheuristic Computing (AMC) has been a prevailing optimization technique for tackling perplexing engineering and business problems, such as scheduling, routing, ordering, bin packing, assignment, facility layout planning, among others. This is partly because the classic exact methods are constrained with prior assumptions, and partly due to the heuristics being problem-dependent and lacking generalization. AMC, on the contrary, guides the course of low-level heuristics to search beyond the local optimality, which impairs the capability of traditional computation methods. This topic series has collected quality papers proposing cutting-edge methodology and innovative applications which drive the advances of AMC

    Space, people, networks:exploring the relationship between built structures and seamless wireless communication infrastructures

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    In this thesis, I investigate wireless communication from an architectural perspective. I am using design prototypes to explore possibilities for interaction and designing with wirelessness in mind. The public primarily regards wireless networking technology as a technical infrastructure that should provide a seamless flow of information across a network of base stations, access points and mobile devices. From this perspective, wireless infrastructure is evaluated in terms of network availability and speed, and is continuously optimised. Researchers explored some other perspectives on wireless communication technology: they used computational spatial analysis to measure signal propagation in space. Some ethnographic studies explored its effect on the use of public space. Wireless connectivity was also explored through the philosophical framework of radical empiricism. All this points to the fact that wireless network infrastructure is a complex topic, spanning multiple fields of expertise and interest (engineering, architecture, urban studies but also sociology and philosophy). It is rarely explored from a plural perspective, as each study typically focuses on the one aspect within its expertise. I propose a more complex view of wireless connectivity, encompassing these different perspectives through an intellectual framework that is based on the notion of architecturality. Architecturality, a property common to all architecture but exceeding the limits of built artefacts, is a measure of the effect something has on the experience of space. Through the lens of the built environment, I expose the complex transactions that take place between networks, people and space. In order to evaluate architecturality of wireless communication signals, I conducted a series of practical design experiments, involving people and interactive installations, and using data gathered from mobile devices and wireless access points. The design of these experiments relies on the principles described by human-computer interaction (HCI) researchers as seamful design. Seamful design reveals underlying structures and relationships behind what appears as a utilitarian infrastructure. The design experiments contribute to the discussion on the use of design artefacts in practice-based research methodologies, thus challenging the different agents of knowledge production and the superiority of established research traditions. The insights gained from this complex examination of wireless networks are important for architectural design, as a way to account more adequately for signal propagation through buildings. The experience of internalising wireless networks in the process of design engenders a designerĂąs sensitivity towards the presence of wireless communications in space. This sensitivity, similar to the one we have for the distribution of natural and artificial lighting, will be needed in the ever more challenging design of the built environment. The sensible designer can account for, and envision, more dynamic environments that are able to accommodate change and information in completely new ways

    User mobility prediction and management using machine learning

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    The next generation mobile networks (NGMNs) are envisioned to overcome current user mobility limitations while improving the network performance. Some of the limitations envisioned for mobility management in the future mobile networks are: addressing the massive traffic growth bottlenecks; providing better quality and experience to end users; supporting ultra high data rates; ensuring ultra low latency, seamless handover (HOs) from one base station (BS) to another, etc. Thus, in order for future networks to manage users mobility through all of the stringent limitations mentioned, artificial intelligence (AI) is deemed to play a key role automating end-to-end process through machine learning (ML). The objectives of this thesis are to explore user mobility predictions and management use-cases using ML. First, background and literature review is presented which covers, current mobile networks overview, and ML-driven applications to enable user’s mobility and management. Followed by the use-cases of mobility prediction in dense mobile networks are analysed and optimised with the use of ML algorithms. The overall framework test accuracy of 91.17% was obtained in comparison to all other mobility prediction algorithms through artificial neural network (ANN). Furthermore, a concept of mobility prediction-based energy consumption is discussed to automate and classify user’s mobility and reduce carbon emissions under smart city transportation achieving 98.82% with k-nearest neighbour (KNN) classifier as an optimal result along with 31.83% energy savings gain. Finally, context-aware handover (HO) skipping scenario is analysed in order to improve over all quality of service (QoS) as a framework of mobility management in next generation networks (NGNs). The framework relies on passenger mobility, trains trajectory, travelling time and frequency, network load and signal ratio data in cardinal directions i.e, North, East, West, and South (NEWS) achieving optimum result of 94.51% through support vector machine (SVM) classifier. These results were fed into HO skipping techniques to analyse, coverage probability, throughput, and HO cost. This work is extended by blockchain-enabled privacy preservation mechanism to provide end-to-end secure platform throughout train passengers mobility
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