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  • 201.
    Bria, Aurelian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Joint Resource Management of Cellular and Broadcasting Systems - Research Challenges2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    One of the ways towards provision of low-cost mobile multimedia entertainment is to make possible the sharing of the wireless resources among multiple operators of different radio access technologies. Here we discuss opportunities for new system architectures enabled by sharing the resources belonging to the cellular and broadcasting systems, namely the spectrum and the infrastructure. The goal of this paper is to identify the bottlenecks of such architectures and the challenges that have to be addressed on their path towards a functional system able to deliver low-cost mobile multimedia services.

  • 202.
    Bria, Aurelian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Mobile Multimedia Multicasting in Future Wireless Systems: A Hybrid Cellular-Broadcasting System Approach2008Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    This dissertation addresses the problem of providing a®ordable mobile mul-timedia services in wide area wireless networks. The approach is to con-sider novel system architectures, based on reusing and sharing of the ex-isting network infrastructure for cellular and terrestrial TV broadcastingsystems. The focus has been on the radio resource management techniques,and the evaluation of the potential cost savings, compared to traditionalevolution tracks of the cellular and broadcasting systems.The studies show that deployment cost of a wide area broadcastingnetwork, using DVB-H technology, is very large if high data rate and fullarea coverage is targeted. For this reason we propose to avoid the broad-casting infrastructure dimensioning for full area coverage, and use insteadthe cellular systems to enable error correction for broadcasting transmis-sions. For the special case of mobile users, the chosen approach is to tradesystem's cost and capacity for improved perceived coverage. This trade-o®is enabled by the use of application layer forward error correction, usingRaptor coding.The general purpose Ambient Networks technology was chosen to en-able a platform for inter-operability between cellular and broadcasting sys-tems, especially the necessary interfaces. Under the Ambient Networksframework, we investigate the achievable cost savings o®ered by a hybridcellular-broadcasting system when combinations of broadcast and point-to-point transmissions are jointly utilized to provide ¯le transfers and stream-ing services. Two cases were investigated: one where the cellular systemacts as a replacement and deliver the data in the areas where broadcastingtransmissions cannot reach, and another one where cellular system carriesparity data to users that experience temporary outage in the broadcastingsystem. The results are encouraging, as they show that ¯le transfer costcan be reduced by more than 50%, but only under certain conditions.On a short term, hybrid cellular-broadcasting systems based on 3G andDVB-H, o®er a good platform for testing new and innovative mobile TVservices, enriched with interactivity and content personalization. From atechnical perspective, the outcomes of the presented studies indicate thatfuture systems built on hybrid cellular-broadcasting infrastructures are ableprovide a long term and cost e±cient solution for delivery of a®ordablebroadband multimedia services to mobile users. However, today's cellularand broadcasting systems live in di®erent worlds, are driven by di®erentrevenue models, and they are now starting to compete, instead of cooperate,for controlling the multimedia delivery channels to mobile users.

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    FULLTEXT01
  • 203.
    Bria, Aurelian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Performance of Cost-Based Resource Management in Cellular-Broadcasting Systems with Multicast Push Traffic2005Rapport (Övrigt vetenskapligt)
  • 204.
    Bria, Aurelian
    et al.
    KTH, Tidigare Institutioner (före 2005), Signaler, sensorer och system.
    Flament, Maxime
    Chalmers University of Technology.
    Gessler, Fredrik
    KTH, Tidigare Institutioner (före 2005), Industriell ekonomi och organisation.
    Queseth, Olav
    KTH, Tidigare Institutioner (före 2005), Signaler, sensorer och system.
    Stridh, Rickard
    KTH, Tidigare Institutioner (före 2005), Signaler, sensorer och system.
    Unbehaun, Matthias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Wu, Jiang
    KTH, Tidigare Institutioner (före 2005), Mikroelektronik och informationsteknik, IMIT.
    Zander, Jens
    KTH, Tidigare Institutioner (före 2005), Wireless at KTH.
    Overall design of 4th Generation Wireless Infrastructures (4GW)2002Konferensbidrag (Refereegranskat)
    Abstract [en]

    An important factor contributing to this uncertainty is that we have very limited knowledge about the future environment in which a fourth generation wireless infrastructure should function. Which of today's systems will still exist when a potential 4G infrastructure is deployed? Which systems and solutions will be considered successful then? What technical bottlenecks will be apparent ten years from now? What market impact will third generation wireless systems have? How will this affect user behavior, and user demands? How much money do prospective users have available to pay for services provided over this infrastructure? This paper presents some of the conclusion of of the Fourth Generation Wireless Infrastructure project (4GW) of the Personal Computing and Communications program (PCC), the major Swedish academic research effort on future communications systems launched in late 1997(1). The vision of the PCC project has been "Personal Multimedia to everyone at today's prices for fixed telephony". In 4GW a scenario-based approach has been used to tackle the issue of identifying reasonable research topics. In the paper we will present this method, and demonstrate how it interfaces with traditional research methods in the fields that the 4GW project incorporates. We will also give an overview of some research results from the project. Finally, we will conclude these results as a vision of what fourth generation wireless infrastructures might become

  • 205.
    Bria, Aurelian
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    González Font, Álvaro
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Cost-Based Resource Management for Filecasting Services in Hybrid DVB-H and 3G systems2008Ingår i: 2008 IEEE INTERNATIONAL SYMPOSIUM ON WIRELESS COMMUNICATION SYSTEMS (ISWCS 2008), NEW YORK: IEEE , 2008, s. 159-163Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper describes and evaluates a novel resource management technique for minimizing the file transmission cost in a hybrid cellular-broadcasting system. While DVB-H technology is utilized for wide area broadcasting, the 3G-HSDPA(1) system takes the role of providing not only feedback about reception conditions, but also on-demand repair information to the users that have missed part of the DVB-H transmissions. The Application Layer - Forward Error Correction with Raptor coding is used to generate parity data that is sent to the users through both cellular and broadcasting system. Our results show significant potential for cost reduction under certain settings and scenarios. Overall, we think that the outcomes of this study should encourage the interworking of cellular 3G and DVB-H broadcasting systems, in an effort to achieve cost efficient delivery of multimedia content to mobile users.

  • 206.
    Bria, Aurelian
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Gómez-Barquero, David
    Scalability of DVB-H deployment on existing wireless infrastructure2005Ingår i: IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, IEEE , 2005, s. 716-720Konferensbidrag (Refereegranskat)
    Abstract [en]

    This article investigates the scalability of DVB-H deployment on existing wireless infrastructure for digital broadcasting and cellular networks. Three deployment strategies are investigated: when only the broadcasting and the cellular infrastructure are used separately, and the case when both can be used jointly. The outcomes show that, in general, the investment needed for increasing the service capacity by switching to higher order modulation, or for increasing the coverage level over a given service area, lead to a higher annualized cost per Mb/s.

  • 207.
    Bria, Aurelian
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Kärrberg, Patrik
    London School of Economics and Political Science.
    Andersson, Per
    Stockholm School of Economics.
    TV in the Mobile or TV for the Mobile: Challenges and Changing Value Chains2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper intends to provide a techno-economic overview of the Mobile TV business and its business models. Recent trials have shown that a large number of people would like to consume mobile TV and few people doubt that this service will eventually be offered in the majority of wireless networks around the world. However, this service is not a simple add-on to the voice and data, but comes with totally new dimensions that challenge the present markets. The aim of this paper is to identify and describe these challenges in the technology, market behaviour, and industry strategy domains.

  • 208.
    Bria, Aurelian
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Markendahl, Jan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, KTH Center för Trådlösa System, Wireless@kth.
    Rembarz, Rene
    Ericsson Research,.
    Pöyhönen, Petteri
    Nokia Siemens Networks.
    Simon, Csaba
    Technical University Budapest.
    Miozzo, Marco
    Consorzio Ferrara Ricerche.
    Akhtar, Nadeem
    University of Surrey.
    Jennen, Ralf
    RWTH Aachen University.
    Validation of the Ambient Networks System Architecture2007Ingår i: Proceedings of the Second International Conference on Communications and Networking in China, ChinaCom 2007, IEEE , 2007, s. 784-791Konferensbidrag (Refereegranskat)
    Abstract [en]

    The Ambient Networks project develops a complete and coherent solution for control architectures in future networks. In particular, the concept of Ambient Control Space has been proposed to support a technology-agnostic, modular and dynamic control plane. The second phase of the project (2006-2007) has an increased focus on validation, where two complementary tracks are being followed: proof-of- concept prototyping and performance evaluation through simulations. The prototype modules, focusing on requirement engineering, were validated during the process of integrating them into a common control space prototype, which was later used to build the demonstration setups. The system performance evaluation through simulations deals with aspects such as capacity utilization, reachability, cost and performance trade-offs and also provides evidence that the additional AN features (e.g., composition) do not introduce excessive signaling overhead. We target different composition aspects, advertising & discovery, negotiation of composition agreements and their interaction with multi-radio access and mobility control. Our validation approach is based on several use cases.

  • 209.
    Brodén, Cyrus
    et al.
    Department of Molecular Medicine and Surgery, Karolinska Institutet.
    Olivecrona, Henrik
    Department of Molecular Medicine and Surgery, Karolinska Institutet.
    Maguire Jr., Gerald Q.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Noz, Marilyn E.
    New York University, Department of Radiology.
    Zeleznik, Michael P.
    School of Computing, College of Engineering, University of Utah.
    Sköldenberg, Olof
    Department of Clinical Sciences, Danderyd Hospital, Karolinska Institutet.
    Accuracy and Precision of Three-Dimensional Low Dose CT Compared to Standard RSA in Acetabular Cups: An Experimental Study2016Ingår i: BioMed Research International, ISSN 2314-6133, E-ISSN 2314-6141, artikel-id 5909741Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background and Purpose. The gold standard for detection of implant wear and migration is currently radiostereometry (RSA). The purpose of this study is to compare a three-dimensional computed tomography technique (3D CT) to standard RSA as an alternative technique for measuring migration of acetabular cups in total hip arthroplasty.

    Materials and Methods. With tantalum beads, we marked one cemented and one uncemented cup and mounted these on a similarly marked pelvic model. A comparison was made between 3D CT and standard RSA for measuring migration. Twelve repeated stereoradiographs and CT scans with double examinations in each position and gradual migration of the implants were made. Precision and accuracy of the 3D CT were calculated.

    Results. The accuracy of the 3D CT ranged between 0.07 and 0.32 mm for translations and 0.21 and 0.82° for rotation. The precision ranged between 0.01 and 0.09 mm for translations and 0.06 and 0.29° for rotations, respectively. For standard RSA, the precision ranged between 0.04 and 0.09 mm for translations and 0.08 and 0.32° for rotations, respectively. There was no significant difference in precision between 3D CT and standard RSA. The effective radiation dose of the 3D CT method, comparable to RSA, was estimated to be 0.33 mSv.

    Interpretation. Low dose 3D CT is a comparable method to standard RSA in an experimental setting.

  • 210. Browall, C.
    et al.
    Tollmar, Konrad
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Petterson, F.
    Camelot - Rundabordssamtal och seminarier kring framtidens boende (A workshop serie about domestic technologies)2002Bok (Övrigt vetenskapligt)
  • 211.
    Bude, Cristian
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Kervefors Bergstrand, Andreas
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Internet of Things: Exploring and Securing a Future Concept2015Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Internet of Things (IoT) är ett koncept som omfattar olika objekt och kommunikationsmetoder för utbyte av information. Idag är IoT mer en beskrivande term av den framtidsvision som finns att allting ska vara uppkopplat på internet. IoT kommer vara fundamentalt i framtiden eftersom konceptet öppnar upp möjligheter för nya tjänster samt nya innovationer. Då alla objekt ska vara uppkopplade och kunna kommunicera med varandra samtidigt som de skall kunna operera i oskyddade miljöer, bidrar detta till stora säkerhetsutmaningar.

    Dagens IoT är i stort behov av standardisering och klara strukturer för hur tekniken ska implementeras samt samverka med varandra på ett säkert sätt.  Utmaningarna ligger i att säkra tekniken samt informationen som tekinken bidrar med. Denna rapport ger en introduktion till vad IoT är och hur det kan användas samt vilka hot som IoT kan möta i avseende till informationssäkerhet. Utöver detta så förser rapporten läsaren med förslag om hur man eventuellt kan lösa de fundamentala behoven av autentisering och säker kommunikation. Lösningarna som läggs fram är baserade på både nutida lösningar och teknik som är under utveckling inför framtiden. Nutida lösningar är baserade på säkerhetsprotokoll som IPsec och DTLS som används i en miljö som sträcker över internet och in i ett 6LoWPAN nätverk. Den autentiseringslösning som tagits fram grundar sig på PKI och förtroendemodeller för certifikathantering.

    För framtida arbete presenteras flertalet vidare fördjupningsområden där denna rapport kan användas som grund. Dessa fördjupningsområden inkluderar vidare analys av sårbarheter och implementation av de lösningar som tagits fram.

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  • 212.
    Bui, Minh N.
    et al.
    Concordia University.
    Jaumard, Brigitte
    Concordia University.
    Cavdar, Cicek
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, KTH Center för Trådlösa System, Wireless@kth.
    Mukherjee, Biswanath
    University of California - Davis.
    Design of a survivable VPN topology over a service provider network2013Ingår i: 2013 9th International Conference on the Design of Reliable Communication Networks (DRCN), IEEE conference proceedings, 2013, s. 71-78Konferensbidrag (Refereegranskat)
    Abstract [en]

    Survivability in IP-over-WDM networks has alreadybeen extensively discussed in a series of studies. Up to date,most of the studies assume single-hop working routing of trafficrequests. In this paper, we study the multi layer survivable designof a logical topology in the context of multiple-hop workingrouting for IP layer traffic requests. The design problem iscomposed of two problems which are simultaneously solved:(i) Finding the most efficient or economical multi-hop routingof the IP traffic flows with different bandwidth granularitiesover the logical topology, which involves some traffic grooming,(ii) Ensuring that the logical topology is survivable throughoutan appropriate mapping of the logical links over the physicaltopology, if such a mapping exists.In order to solve such a complex multi layer resilient networkdesign problem, we propose a column generation ILP model. Itallows exploiting the natural decomposition of the problem andhelps devising a scalable solution scheme.We conducted numerical experiments on a German networkwith 50 nodes and 88 physical links. Not only we could solve muchlarger data instances than those published in the literature, butalso observe than multi-hop routing allows a saving of up to 10%of the number of lightpaths, depending on the traffic load.

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    DRCN-2013
  • 213. Bulakci, O.
    et al.
    Gutierrez-Estevez, D. M.
    Ericson, M.
    Prasad, A.
    Pateromichelakis, E.
    Calochira, G.
    Belschner, J.
    Arnold, P.
    Moya, F. Sanchez
    Ibrahim, A. M.
    Bronzino, F.
    Čelik, Haris
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Fodor, G.
    An Agile Resource Management Framework for 5G2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents the design foundations of an agile resource management (RM) framework for the fifth generation (5G) radio access network (RAN) by describing essential building blocks (BBs). Overall, the presented RM framework provides holistic RM solutions that consider and exploit the novel aspects of 5G systems, such as, diverse service requirements, co-existence of multiple air interface (AI) variants (AIVs) in the overall AI, dynamic radio topologies, and novel communication modes. The proposed framework encompasses the following key BBs: Advanced interference management techniques for dense and dynamic deployments; dynamic traffic steering mechanisms that aim to attain the optimum mapping of 5G services to any available resources when and where needed by considering the peculiarities of different AIVs; tight interworking between novel 5G AIVs and evolved legacy AIVs such as Longterm Evolution (LTE); sharing of a common RAN by multiple network slices; RAN moderation techniques to attain energy efficiency gains; and functional extensions in the device measurement context to enable all the above new functionalities. The BBs are analyzed from the perspectives of key findings and RAN design implications.

  • 214. Bulakei, Omer
    et al.
    Prasad, Athul
    Belschner, Jakob
    Ericson, Marten
    Karls, Ingolf
    Celik, Haris
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Tesanovic, Milos
    Fantini, Roberto
    Campoy, Luis M.
    Pateromichelakis, Emmanouil
    Moya, Fernando Sanchez
    Zimmermann, Gerd
    Da Silva, Icaro
    Agile Resource Management for 5G A METIS-II Perspective2015Ingår i: 2015 IEEE CONFERENCE ON STANDARDS FOR COMMUNICATIONS AND NETWORKING (CSCN), 2015, s. 30-35Konferensbidrag (Refereegranskat)
    Abstract [en]

    An explosive growth in the demand for higher data rates and capacity along with diverse requirements set by massive and ultra-reliable machine-type communications are the main drivers behind the development on new access technologies as part of the fifth generation (5G) networks. Currently, different air interface (AIF) and/or AIF variants, optimized based on the frequency band of operation and use case, are envisioned for such a network. Developing an agile resource management framework for 5G networks is one of the main goals of the METIS-II project. The METIS-II project builds strongly upon the EU flagship project METIS, which has laid the foundation of 5G. This framework will take into account the multi-link and multi-layer constraints currently envisioned for 5G. In this paper, we provide our first insights into agile resource management and the associated synchronous control functions. We will discuss the essential building blocks in terms of technology enablers and their mapping to 5G services and deployments. The introduced agile resource management framework for 5G is expected to enable enhanced interference management, dynamic traffic steering, fast radio access network (RAN) moderation, efficient context management, and optimized integration with legacy networks.

  • 215. Buysse, Jens
    et al.
    Cavdar, Cicek
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, KTH Center för Trådlösa System, Wireless@kth.
    De Leenheer, M.
    Dhoedt, B.
    Develder, Chris
    Improving energy efficiency in optical cloud networks by exploiting anycast routing2011Ingår i: NETWORK ARCHITECTURES, MANAGEMENT, AND APPLICATIONS IX / [ed] Wosinska, L; Sato, KI; Wu, J; Zhang, J, SPIE - International Society for Optical Engineering, 2011, s. 1-6, artikel-id 83100XKonferensbidrag (Refereegranskat)
    Abstract [en]

    Exploiting anycast routing significantly reduces optical network and server energy usage. In this work we present a case study showing that intelligently selecting destinations and routes thereto, while switching off unused (network) elements, cuts power consumption by around 20% and saves network resources by 29%.

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  • 216. Byamukama, Maximus
    et al.
    Nannono, Janet Nakato
    Ruhinda, Kabonire
    Pehrson, Björn
    KTH.
    Nsabagwa, Mary
    Akol, Roselyn
    Olsson, Robert
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Network Systems Laboratory (NS Lab).
    Bakkabulindi, Geoffrey
    Kondela, Emmanuel
    Design Guidelines for Ultra-low Power Gateways in Environment Monitoring Wireless Sensor Networks2017Ingår i: 2017 IEEE AFRICON / [ed] Cornish, D R, Institute of Electrical and Electronics Engineers (IEEE), 2017, s. 1472-1478Konferensbidrag (Refereegranskat)
    Abstract [en]

    We explore techniques that can be used to reduce the power consumption of gateways in wireless sensor networks deployed in environment monitoring applications, such as Automatic Weather Stations (AWS). The challenge is the deployment of these networks in locations that are far from a consistent power source, such as a national grid. Such stations must be autonomous and power consumption must be minimized. We present test scenarios illustrating the impact of the suggested techniques. We explore hardware and software based methods of power reduction, assess the impact of each, the constraints to be expected and how to overcome them. We then provide a reference implementation of a gateway in which we integrate these techniques. We show that power consumption can be reduced by 48 - 85% when comparing best and worst case scenarios. The reference implementation we provide consumes 27mW at 3V.

  • 217.
    Cabarkapa, Dragan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Authorization Architecture for SWoT2013Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    "Social Web of Things" (SWOT) är en användarcentrerad ram som underlättar samverkan mellan agenter som körs på smarta saker och i molnet. Agenter som körs på smarta saker är fjärråtkomst, värd känsliga resurser, och ofta utgör högt värde mål. För närvarande SWOT ramverket omfattar inte lämpliga säkerhetsmekanismer som skulle kunna skydda dessa agenter från obehörig åtkomst. I denna uppsats vill vi rätta till detta brist genom att införa plattformsoberoende, flexibel och användarvänlig centrerad auktorisation mekanism i SWOT ramen.

    Vi härleda krav och design av abstrakt tillstånd arkitektur från föregående sädes-arbete som utförs i ett SENSEI projektet. SENSEI och SWOT delar samma problem domän, men samtidigt SENSEI behandlar ärenden företagsbruk SWOT fokuserar på konsumenten användningsfall. Denna singel men grundläggande skillnaden motiverar anpassningar av SENSEI avgifter för ansökan i SWOT. Till realisera konkreta tillstånd arkitektur vi utför ett omfattande studie av olika lösningar för tillstånd. Resultat av vår studie tyder på att en ny användarhanterad tillgång (UMA) Protokollet utgör lovande lösning för SWOT.

    Vi presenterar tillståndet som en service lösning för SWOT ramverk, baserat på UMA-protokollet. Denna lösning gör det möjligt för användare att hantera och kontrollera kommunikationen mellan agenter utplacerade på smarta saker och i molnet från enstaka centraliserad plats. Dessutom gör vår lösning dynamisk sammanslutning av agenter, ledning, utvärdering och tillsyn av tillträde behörigheter för resurser som tillhandahålls av agenter.

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  • 218.
    Cavdar, Cicek
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Ruiz, M.
    Monti, Paolo
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Velasco, L.
    Wosinska, Lena
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Design of green optical networks with signal quality guarantee2012Ingår i: IEEE International Conference on Communications, IEEE , 2012, s. 3025-3030Konferensbidrag (Refereegranskat)
    Abstract [en]

    Energy consumption of communication networks is growing very fast due to the rapidly increasing traffic demand. Consequently, design of green communication networks gained a lot of attention. In this paper we focus on optical Wavelength Division Multiplexing (WDM) networks, able to support this growing traffic demand. Several energy-aware routing and wavelength assignment (EA-RWA) techniques have been proposed for WDM networks in order to minimize their operational cost. These techniques aim at minimizing the number of active links by packing the traffic as much as possible, thus avoiding the use of lightly loaded links. As a result, EA-RWA techniques may lead to longer routes and to a high utilization on some specific links. This has a detrimental effect on the signal quality of the optical connections, i.e., lightpaths. In this study we quantify the impact of power consumption minimization on the optical signal quality. and address this problem by proposing a combined impairment and energy-aware RWA (IEA-RWA) approach. Towards this goal we developed a complete mathematical model that incorporates both linear and non-linear physical impairments together with an energy efficiency objective. The IEA-RWA problem is formulized as a Mixed Integer Linear Programming (MILP) model where both energy efficiency and signal quality considerations are jointly optimized. By comparing the proposed IEA-RWA approach with existing RWA (IA-RWA and EA-RWA) schemes, we demonstrate that our solution allows for a reduction of energy consumption close to the one obtained by EA-RWA approaches, while still guaranteeing a sufficient level of the optical signal quality.

  • 219.
    Cedervall, Catarina
    et al.
    TeliaSonera Sweden.
    Karlsson, Peter
    TeliaSonera Sweden.
    Prytz, Mikael
    Ericsson Research.
    Hultell, Johan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Markendahl, Jan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Bria, Aurelian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Rietkerk, Oscar
    TNO, The Netherlands.
    Karla, Ingo
    Alcatel, Germany.
    Initial findings on business roles, relations and cost savings enabled by Multi-Radio Access Architecture in Ambient Networks2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    The multi-radio access architecture within the ambient network concept opens up opportunities for new business roles within the mobile and wireless domain. The new business roles take advantage of the control plane functionality that enables cost efficient connectivity over heterogeneous radio access technologies.

  • 220.
    Celik, Haris
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    On the Performance of Dynamic TDD in Ultra-Dense Wireless Access Networks2017Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The appetite for wireless high-data rate services is expected to continue for many years to come and drive the need for more capacity. Ultra-dense networks (UDNs) represent a paradigm shift where each base station (BS) serves only a few user equipments (UEs). By most accounts, most of the traffic will be generated indoor and operate in time-division duplex (TDD). This thesis considers dynamic TDD which has shown to perform well indoor for fluctuating traffic where the shorter communication range enables similar transmit powers to be used in uplink and downlink, but also generates potentially more harmful same-entity interference. Because of the sheer number of cells in UDN, the interference management needs to be both effective and scalable.

     

    In the first part of the thesis, we compare static TDD with non-cooperative dynamic TDD and show that flexible time resource allocation is preferred for indoor UDNs. However, since it only provides a lower bound on performance, additional interference coordination is required. Unfortunately, existing schemes often consider either too few, too many, or simply the wrong interferers. We introduce a scheduling model that relates BS-to-BS interferences measured offline to individual BS activation probability taking into account traffic and propagation environment. Results show that the proposed scheme performs well when interference is high, and optimally when interference is low.

     

    In the second part, we introduce cooperation to utilize the otherwise idle BSs and mitigate same- and other entity interference. Zero forcing (ZF) is employed in the downlink where not only downlink UEs but also uplink BSs are included in the precoding. Since downlink BSs do not know the information to be sent by uplink UEs beforehand, dummy symbols with zero power are transmitted. It shown that both uplink and downlink performance improves at low and medium load. Furthermore, it is possible to trade performance in the two directions at high load.

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  • 221.
    Celik, Haris
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab). KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, KTH Center för Trådlösa System, Wireless@kth.
    Sung, Ki Won
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab). KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, KTH Center för Trådlösa System, Wireless@kth.
    On the feasibility of blind dynamic TDD in ultra-dense wireless networks2015Ingår i: IEEE Vehicular Technology Conference, IEEE , 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    Abstract-Dynamic configuring of uplink and downlink switching point in time division duplex (TDD) systems is considered a promising solution to cope with the traffic variations caused by the burstiness of mobile broadband data. However, such dynamic TDD (D-TDD) requires fast inter-cell coordination which may be difficult to implement in ultra-densely deployed networks (UDNs). In order to explore the possibility of designing simplified UDN, we investigate the feasibility of uncoordinated and greedy TDD operation, namely blind D-TDD. It exploits the characteristics of UDN such as low average network utilization and similar transmit power for base stations (BS) and user equipment (UE). To reduce the impact of co- channel interference (CCI), the effect of beamsteering is also evaluated. Our results indicate that blind D-TDD outperforms traditional static TDD (S-TDD) when instantaneous traffic demands for uplink and downlink are highly asymmetric. Also, beamsteering exerts a significant influence on the feasibility of blind D-TDD.

  • 222. Cen, M.
    et al.
    Chen, J.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Moeyaert, V.
    Mégret, P.
    Wuilpart, M.
    A full monitoring scheme for long-reach TWDM PONs2015Ingår i: Asia Communications and Photonics Conference, ACPC 2015, 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    We propose a simple system that realizes for the first time full monitoring functionality for long-reach PON. Theoretical analysis and experimental validation demonstrate the proposed scheme is capable of providing accurate fault localization. 

  • 223. Cen, M.
    et al.
    Chen, Jiajia
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Moeyaert, V.
    Megret, P.
    Wuilpart, M.
    Advanced Transmission-Reflection-Analysis (TRA) system for Long-Reach Passive Optical Network monitoring2015Ingår i: International Conference on Transparent Optical Networks, IEEE Computer Society, 2015, Vol. 2015, artikel-id 7193394Konferensbidrag (Refereegranskat)
    Abstract [en]

    Long-Reach Passive Optical Networks (LR-PONs) allows for extending the distance between the central office (CO) and end users from a few kilometers to several tens of kilometers and beyond. It in turn reduces the number of active equipment in the field, bringing potentially cost saving. However, due to its high capacity and large coverage, LR-PON becomes increasingly vulnerable to various failures. Therefore, network monitoring becomes extremely important to guarantee an appropriate level of network reliability and performance. In this paper, we report on an advanced LR-PON monitoring solution that can supervise the whole LR-PON ring section in a cost-effective manner. Instead of using the conventional optical time domain reflectometry (OTDR) approach, we implement multi wavelength Transmission-Reflection Analysis (nλ-TRA) as the monitoring technique. The TRA approach is based on the unique relationship between the optical powers transmitted and backscattered by the fiber for a given loss location. Since TRA only requires measuring the power levels of monitoring signals, it outperforms other conventional methods thanks to its superior detection speed and a simple system configuration. Both experimental results have demonstrated that the proposed system can reach high accuracy for fault localization.

  • 224. Cen, M.
    et al.
    Chen, Jiajia
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Moeyaert, V.
    Megret, P.
    Wuilpart, M.
    Full monitoring for Long-Reach TWDM Passive Optical Networks based on TRA technique2016Ingår i: International Conference on Transparent Optical Networks, IEEE Computer Society, 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    Long-Reach Passive Optical Networks (LR-PONs) consolidates of metropolitan and access networks by extending the distance between the Central Office (CO) and the end users, which in turn simplifies the network and potentially brings cost savings. With the explosively growing of data traffic, Time and Wavelength Division Multiplexing (TWDM) technology have also been employed in LR-PON to realize high capacity. However, due to high capacity and large coverage, the presence of a single failure may cause a huge loss of data and affect a large number of subscribers in LR-PON. Efficient network fault monitoring therefore becomes a key to improve the level of network reliability. In this paper, we report an advanced solution realizing fault detection, identification and localization in both feeder and distribution fiber segments of TWDM LR-PON. Instead of using the conventional optical time domain reflectometry (OTDR) approach, we implement multi wavelength Transmission-Reflection Analysis (nλ-TRA) as the monitoring technique, which is able to provide a good spatial accuracy and a high detection speed without interfering with the data traffic. Theoretical analysis and experimental validation demonstrate that the proposed scheme is capable of providing an accurate fault monitoring functionality.

  • 225. Cen, M.
    et al.
    Chen, Jiajia
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Moeyaert, V.
    Mégret, P.
    Wuilpart, M.
    Efficient monitoring for ring-based long-reach passive optical networks2015Ingår i: Optical Fiber Communication Conference, OFC 2015, IEEE conference proceedings, 2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    An efficient monitoring scheme based on transmission-reflection analysis is proposed for long-reach passive optical networks. Both experimental simulation results have demonstrated that the proposed scheme provides better localization functionality than the conventional methods.

  • 226. Cen, M.
    et al.
    Chen, Jiajia
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Mégret, P.
    Moeyaert, V.
    Wuilpart, M.
    Fast and simple fault monitoring for long-reach passive optical networks2014Ingår i: 2014 European Conference on Optical Communication, (ECOC), IEEE , 2014, s. 6964070-Konferensbidrag (Refereegranskat)
    Abstract [en]

    We propose a fast and simple monitoring system based on multi-wavelength bi-directional transmission reflection analysis approach for long-reach passive optical networks. Both experimental and simulation results have demonstrated the proposed system can reach high accuracy for fault localization.

  • 227. Cen, Min
    et al.
    Chen, Jiajia
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Moeyaert, Veronique
    Megret, Patrice
    Wuilpart, Marc
    Advanced Fault-Monitoring Scheme for Ring-Based Long-Reach Optical Access Networks2017Ingår i: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 35, nr 10, s. 1876-1886Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents a novel fiber fault-monitoring system for long-reach optical access networks based on a transmission-reflection analysis approach. By launching an un-modulated continuous-wave optical signal into the feeder ring and measuring the transmitted and reflected/backscattered optical powers, the proposed monitoring scheme is able to detect, identify, and localize any major fault (covering both reflective and nonreflective events) with a good spatial accuracy (<= 10 m) and a high detection speed (3 s). Both experimental and simulation results have demonstrated that the proposed system provides fiber monitoring functionality better than that obtained by the conventional methods.

  • 228. Cen, Min
    et al.
    Chen, Jiajia
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab). South China Normal University, China.
    Moeyaert, Veronique
    Megret, Patrice
    Wuilpart, Marc
    Full monitoring for long-reach TWDM passive optical networks2016Ingår i: Optics Express, E-ISSN 1094-4087, Vol. 24, nr 14, s. 15782-15797Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents a novel and simple fiber monitoring system based on multi-wavelength transmission-reflection analysis for long-reach time and wavelength division multiplexing passive optical networks. For the first time, the full localization functionality of long-reach passive optical networks is possible with the proposed monitoring scheme, including supporting fault detection, identification, and localization in both feeder and distribution fiber segments. By measuring the transmitted and reflected/backscattered optical powers launched by an unmodulated continuous-wave optical source, the proposed solution is able to supervise the network with good spatial accuracy, a high detection speed and a low impact on data traffic. Both the theoretical analysis and experimental validation show that the proposed scheme is capable of providing an accurate fault monitoring functionality for long-reach time and wavelength division multiplexing passive optical networks.

  • 229. Cen, Min
    et al.
    Chen, Jiajia
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Moeyaert, Veronique
    Megret, Patrice
    Wuilpart, Marc
    Multi-wavelength transmission-reflection analysis for fiber monitoring2014Ingår i: Optics Express, E-ISSN 1094-4087, Vol. 22, nr 25, s. 31248-31262Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We propose and implement a novel approach based on multi-wavelength Transmission-Reflection Analysis (MW-TRA) technique for monitoring lossy events (e.g. disconnected connectors, fiber breaks and fiber bendings) along an optical fiber link. By launching un-modulated continuous-wave lights carried by different wavelengths into the fiber and measuring their transmitted and reflected/backscattered optical powers, our proposed MW-TRA scheme is able to localize any lossy event (including both reflective and non-reflective) and to quantify the corresponding insertion and return losses with high accuracy.

  • 230. Cervero, A. G.
    et al.
    Chincoli, Michele
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Dittmann, L.
    Fischer, A.
    Garcia, A. E.
    Galán-Jiménez, J.
    Lefevre, L.
    de Meer, H.
    Monteil, T.
    Monti, Paolo
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Orgerie, A.
    Pau, L.
    Phillips, C.
    Ricciardi, S.
    Sharrock, R.
    Stolf, P.
    Trinh, T.
    Valcarenghi, L.
    Green Wired Networks2015Ingår i: Large-scale Distributed Systems and Energy Efficiency: A Holistic View, Wiley-Blackwell, 2015, s. 41-80Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    This chapter first highlights the significant energy consumption of existing wired communication networks. It considers various means of operating such networks more efficiently. Then, the chapter examines the components that make up a wired communications network and their differing characteristics between the access and core, as well as patterns of traffic behavior. The chapter focuses on static (network planning) and dynamic (traffic-engineering) schemes that can be used to reduce the energy consumption of networks. It also pays attention to a number of challenges/open research questions that need to be resolved before the implementation of such schemes. These include issues with migration and resilience. The chapter then deals with economic-, regulatory-, and business-related methods. Finally, it focuses on the architecture of communication networks and the corresponding relationship with energy usage.

  • 231.
    Chang, Peiliang
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Area Spectral and Energy Efficiency Analysis of Cellular Networks with Cell DTX2015Ingår i: IEEE Globecom 2015 , San Diego, December 6th-10th, 2015, IEEE conference proceedings, 2015, s. 1-6Konferensbidrag (Refereegranskat)
    Abstract [en]

    Cell discontinuous transmission (DTX) has been proposed as an effective solution to reduce energy consumption of cellular networks. In this paper, we investigate the impact of network traffic load on area spectral efficiency (ASE) and energy efficiency (EE) of cellular networks with cell DTX. Closedform expressions of ASE and EE as functions of traffic load for cellular networks with cell DTX are derived. It is shown that ASE increases monotonically in traffic load, while EE depends on the power consumption of base stations in sleep mode. If this power consumption is larger than a percentage of the active-mode power consumption, EE increases monotonically with traffic load and is maximized when the network is fully loaded. Otherwise, EE first increases and then decreases in traffic load. In this case, ASE and EE are maximized with different loads. The percentage threshold only depends on the path loss exponent of radio propagation environment and is calculated to be 56.2% when the path loss exponent is 4.

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  • 232.
    Chang, Peiliang
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Miao, Guowang
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Energy and Spectral Efficiency of Cellular Networks with Discontinuous Transmission2017Ingår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 16, nr 5, s. 2991-3002Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cell discontinuous transmission (DTX) has been proposed as a solution to reduce energy consumption of cellular networks. This paper investigates the impact of network traffic load on spectral and energy efficiency of cellular networks with DTX. The SINR distribution as a function of traffic load is derived firstly. Then sufficient condition for ignoring thermal noise and simplifying the SINR distribution is investigated. Based on the simplified SINR distribution, the network spectral and energy efficiency as functions of network traffic load are derived. It is shown that the network spectral efficiency increases monotonically in traffic load, while the optimal network energy efficiency depends on the ratio of the sleep-mode power consumption to the active-mode power consumption of base stations. If the ratio is larger than a certain threshold, the network energy efficiency increases monotonically with network traffic load and is maximized when the network is fully loaded. Otherwise, the network energy efficiency firstly increases and then decreases in network traffic load. The optimal load can be identified with a binary search algorithm. The power ratio threshold depends solely on the path loss exponent α, e.g. 56% for α = 4. All these analytic results are further validated by the numerical simulations.

  • 233.
    Chang, Peiliang
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Miao, Guowang
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Joint Optimization of Base Station Deep-Sleep and DTX Micro-Sleep2016Ingår i: 2016 IEEE Globecom Workshops, GC Wkshps 2016 - Proceedings, IEEE conference proceedings, 2016, artikel-id 7848943Konferensbidrag (Refereegranskat)
    Abstract [en]

    When both base station (BS) deep-sleep and discontinuous transmission (DTX) are applied to improve network energy efficiency (EE), switching BS into deep-sleep mode would increase the load of remaining active BSs and thereby reduce their energy savings via DTX. This paper studies the optimal BS operation strategy when both deep-sleep and DTX are employed. Queuing theory and stochastic geometry are jointly applied to model network performance with consideration of both traffic dynamics and channel quality variations. Analytical expressions of average BS load and network EE are derived. Both analytical and simulation results show that there is a trade-off between deep-sleep energy saving and DTX energy saving when the energy saving capacity of DTX is considerable. Analytical expression of the optimal percentage of deep-sleep BSs is provided.

  • 234.
    Charvandeh, Jenny
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Location aware web access2009Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Tillgång till information varsomhelst och vilken tid som helst är en viktig utkom av modern rörliga kommunikations systems.

    Alltmera har användarens terminal kännedom om användarens plats. Informationen om platsen kan vara lite eller omfattande. Tillgång till information om platsen gör det möjligt att skapa platsmedvetna tjänster.

    I den här master thesis presenterar och utvärderar jag ett system för plats medvetna web användning. Användaren klickar på en punkt på en karta (för att inrätta en virtuell lokalisering genom att använda tidigare installerat applikationer), sedan deras HTTP GET request för en URL utvidgas med information om användarens position eller deras virtuella (verkliga) lokalisering. En platsmedveten web query har skapats så att information om plats som latitude och longitude läggs till denna web query. Sedan en web server använder denna information för att generera dynamiska web sidor.

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  • 235.
    Chatzaras, Anargyros
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Savvidis, Georgios
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Seamless speaker recognition2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    I ett teknologiskt avancerat samhälle så hanterar den genomsnittliga personen dussintals konton för e-post, sociala nätverk, internetbanker, och andra elektroniska tjänster. Allt eftersom antalet konton ökar, blir behovet av automatisk identifiering av användaren mer väsentlig. Biometri har länge använts för att identifiera personer och är den vanligaste (om inte den enda) metoden för att utföra denna uppgift.

    Smartphones har under de senaste åren blivit allt mer vanligt förekommande, de ger användaren tillgång till de flesta av sina konton och, i viss mån, även personifiering av enheterna baserat på deras profiler på sociala nätverk. Dessa enheter har inbyggda mikrofoner och används ofta av en enskild användare eller en liten grupp av användare, till exempel ett par eller en familj. Denna avhandling använder mikrofonen i en smartphone för att spela in användarens tal och identifiera honom/henne. Befintliga lösningar för talarigenkänning ber vanligtvis användaren om att ge långa röstprover för att kunna ge korrekta resultat.  Detta resulterar i en dålig användarupplevelse och avskräcker användare som inte har tålamod att gå igenom en sådan process. Huvudtanken bakom den strategi för talarigenkänningen som presenteras i denna avhandling är att ge en sömlös användarupplevelse där inspelningen av användarens röst sker i bakgrunden.

    En Android-applikation har utvecklats som, utan att märkas, samlar in röstprover och utför talarigenkänning på dessa utan att kräva omfattande interaktion av användaren. Två varianter av verktyget har utvecklats och dessa beskrivs ingående i denna avhandling. Öpen source-ramverket Recognito används för att utföra talarigenkänningen. Analysen av Recognito visade att det inte klarar av att uppnå tillräckligt hög noggrannhet, speciellt när röstproverna innehåller bakgrundsbrus. Dessutom visade jämförelsen mellan de två arkitekturerna att de inte skiljer sig nämnvärt i fråga om prestanda.

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  • 236.
    Chazalet, Boris
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Opportunistic Content Delivery utilizing Optimized Context Dissemination via the Service Interface in Ambient Networks2007Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    En av Ambient Network viktigast egenskap är användning av kontext information. Kontext i ett Ambient Network omfattar alla sorts information som beskriver nuvarande situation av alla entiten som är kopplad med nätverket (T.ex. lokalisering, tillgängliga konnectivitet och anordningarna osv.). Sådana kontext information kan används av olika applikationer, tjänster eller nätverks resurser, möjligör de kan automatiskt ändrar deras beteende utan användares ingripande. Därför, kontext i Ambient Network ger användaren en bättre upplevelse genom automatiskt konfiguration, uppgörelse och tjänst framförande och transport.

    Detta exjobb presenterar ett optimerad version av kontext utbyt protocolen. Denna protocol är en del av kontext-medveten arkitekture för Ambient Network. Design och arkitekture av den Distributed Context EXchange Protocol (DCXP) använder en P2P överdrag på UDP. Denna design och arkitekture har reviderats för real tids kontext utspridning, samtidigt avsätta flaskhals. En undersökning av denna reviderad design inklusiv mätningar i verkliga scenario, undersökning visar att DXCP erbjuder en praktiskt infall på kontext igenkänning och utspridning, tillåter snabb kontext utbyt och spontan anvädning av nya kontext källor när de blir (inte) tillgängliga i dynamiskt omställning av nätverks konnektivitet, underlätta användning av Ambient Network teknologi. Slutligen, detta exjobb presenterar och demostrerar en ny användning och fördelar med optimerad kontext utspridning som Ambient Networks tjänst gränssnitt (ASI) för läglig kontext leverans. Det är uppnått genom att tillägga en utökning av ASI API, som möjligör en kontext leverans proxy som interagerar med DXCP, och möjligör kontext leverans över Ambient Network.

  • 237.
    Chen, Jiajia
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Efficient resiliency mechanisms for next generation passive optical networks2013Ingår i: ICICS 2013 - Conference Guide of the 9th International Conference on Information, Communications and Signal Processing, IEEE Computer Society, 2013, s. 6782903-Konferensbidrag (Refereegranskat)
    Abstract [en]

    Future broadband access networks are expected to cover large service areas while fulfilling high bandwidth request on a per-user basis. The rapidly increasing traffic demand is also driven by the growing popularity of mobile data services, which is placing high-capacity requirement on the backhaul. Due to advances in wavelength division multiplexing (WDM) technology, WDM based architectures have been considered as promising candidates for next generation optical access, such as WDM passive optical network (PON), and hybrid WDM/time division multiplexing (TDM) PON. Meanwhile, resilience technique will play a more prominent role in emerging access networks due to their significantly increased capacity and coverage compared to the current deployments. Therefore, efficient resiliency mechanisms are highly required to enable uninterrupted network operation where a certain level of reliability performance can be guaranteed. In this work, we first evaluate reliability performance of each segment of next generation optical access networks and then identify the most important part for protection. A particular attention is paid to the reduction of failure impact.

  • 238.
    Chen, Jiajia
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Chen, Bao
    Wosinska, Lena
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    A Novel Joint Scheduling Algorithm for Multiple Services in 10G EPON2008Ingår i: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 7137Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    In this paper, we propose and evaluate a novel joint scheduling algorithm for multiple services which can support differentiated services and bandwidth allocation with global priority of different traffic such as Triple-play: voice, video and Internet services. Simulation results show that for the higher priority traffic better delay and jitter performance can be achieved compared with the lower priority traffic.

  • 239.
    Chen, Jiajia
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Fotonik. KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    De Andrade, M.
    Skubic, Björn
    Ericsson Research.
    Ahmed, Jawwad
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Wosinska, Lena
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Enhancing IPACT with limited service for multi-thread DBA in long-reach EPON2010Ingår i: Communications and Photonics Conference and Exhibition (ACP), 2010 Asia, 2010, s. 629-630Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we propose an enhanced IPACT with limited service for multi-thread DBA in long-reach EPON. We evaluate our scheme by simulations in single-thread and double-thread cases and show that the DBA performance in terms of average delay and jitter can be significantly improved by the proposed algorithm.

  • 240.
    Chen, Jiajia
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Gong, Yu
    Zhejiang Univ, Hangzhou 310027, Peoples R China.
    Fiorani, Matteo
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    High Capacity and Energy Efficient Optical Interconnects at Top of the Rack in Datacentres2014Konferensbidrag (Refereegranskat)
  • 241.
    Chen, Jiajia
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Gong, Yu
    Fiorani, Matteo
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Aleksic, Slavisa
    Optical Interconnects at the Top of the Rack for Energy-Efficient Data Centers2015Ingår i: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 53, nr 8, s. 140-148Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The growing popularity of cloud and multimedia services is dramatically increasing the traffic volume that each data center needs to handle. This is driving the demand for highly scalable, flexible, and energy-efficient networks inside data centers, in particular for the edge tier, which requires a large number of interconnects and consumes the dominant part of the overall power. Optical fiber communication is widely recognized as the highest energy-and cost-efficient technique to offer ultra-large capacity for telecommunication networks. It has also been considered as a promising transmission technology for future data center applications. Taking into account the characteristics of the traffic generated by the servers, such as locality, multi-cast, dynamicity, and burstiness, the emphasis of the research on data center networks has to be put on architectures that leverage optical transport to the greatest possible extent. However, no feasible solution based on optical switching is available so far for handling the data center traffic at the edge tier. Therefore, apart from conventional optical switching, we investigate a completely different paradigm, passive optical interconnects, and aim to explore the possibility for optical interconnects at the top of the rack. In this article, we present three major types of passive optical interconnects and carry out a performance assessment with respect to the ability to host data center traffic, scalability, optical power budget, complexity of the required interface, cost, and energy consumption. Our results have verified that the investigated passive optical interconnects can achieve a significant reduction of power consumption and maintain cost at a similar level compared to its electronic counterpart. Furthermore, several research directions on passive optical interconnects have been pointed out for future green data centers.

  • 242.
    Chen, Jiajia
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Khanmohamadi, Sahar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Fotonik.
    Abtahi, Farzad
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Fotonik.
    Wosinska, Lena
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Xu, Zhenyu
    Cassidy, Andrew
    Tremblay, Christine
    Littlewood, Paul
    Asselin, Serge
    Belanger, Michel P.
    Passive wide area network solutions: Filterless and semi-filterless optical networks2011Ingår i: 13th International Conference on Transparent Optical Networks (ICTON) / [ed] Jaworski, M; Marciniak, M, 2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    Advances in optical coherent transmission and electrical compensation technologies (such as coherent receiver and forward error correction FEC) have stimulated ideas for novel optical network architectures. Recently proposed passive wide area network solution, referred to as filterless optical network [1 #x2013;2] eliminates or minimizes the usage of active photonic reconfigurable network elements. In this approach, only the passive splitters and combiners for interconnecting the fiber links are utilized, which makes this network architecture more cost- and energy-effective as well as more reliable compared with networks based on active optical switching. However, the filterless optical network architecture implies some constraints on fiber interconnection design, maximum fiber-tree length and wavelength reuse due to its broadcast nature. Consequently, filterless solution always requires more resources (i.e. number of wavelengths) compared with the active switched optical networks which are allowed to utilize reconfigurable and coloured components. In order to improve the wavelength utilization while maintaining flexibility of resource allocation, this work extends the idea of filterless optical network by introducing some passive coloured components (e.g., fiber Bragg grating FBG, red/blue filters, etc) to drop local signals at some determined nodes. This approach is referred to as semi-filterless optical network. Furthermore, the semi-filterless solution maintains the passive feature, enabling high reliability and efficiency of cost and energy. Meanwhile, its non-broadcast property at some determined nodes has potential to decrease the transmission impairments and hence relax the constraints on fiber interconnection design and the maximal transparent length, which are strict in the filterless optical network. Our preliminary results confirm the advantages of semi-filterless solution.

  • 243.
    Chen, Jiajia
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Li, Jun
    KTH.
    Efficient Mobile Backhaul Architecture Offering Ultra-Short Latency for Handovers2016Ingår i: 2016 18TH INTERNATIONAL CONFERENCE ON TRANSPARENT OPTICAL NETWORKS (ICTON), IEEE, 2016Konferensbidrag (Refereegranskat)
  • 244.
    Chen, Jiajia
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Lu, Xiang
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Analytical Formulas for Calculating the Blocking Probability of a Dynamic Star Network2005Ingår i: Chinese Optics Letters, ISSN 1671-7694, Vol. 3, nr 10, s. 579-582Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    For a dynamic routing and wavelength assignment (RWA) a star topology is shown to be more efficient in comparison with a ring topology. Analytical formulas for a dynamic RWA in a star network are presented and verified with virtual simulation.

  • 245.
    Chen, Jiajia
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Mahloo, Mozhgan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Wosinska, Lena
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Reducing the Impact of Failures in Next Generation Optical Access Networks2012Ingår i: 2012 Asia Communications And Photonics Conference (ACP), 2012, s. AS1D.2-Konferensbidrag (Refereegranskat)
    Abstract [en]

    Reliability performance of next generation optical access (NGOA) networks offering high bandwidth and large service coverage is evaluated. A particular attention is paid to the reduction of the impact of failures in NGOA.

  • 246.
    Chen, Jiajia
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Poudel, Sunil
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Urban, Patryk
    Fault monitoring for multi-operator and multi-service WDM PON2013Ingår i: Asia Communications and Photonics Conference, ACP 2013, Optical Society of America, 2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    We propose fault supervision mechanisms for open WDM PON, where multiple operators could co-exist and deliver different services on a common fibre plant. The feasibility of such schemes has been validated by evaluating transmission performance.

  • 247.
    Chen, Jiajia
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Urban, P.
    Garcia, J. M.
    Cost-efficient fault supervision schemes for next generation optical access networks (invited)2014Ingår i: Asia Communications and Photonics Conference, ACP, Optical Society of America, 2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents different ways to implement fault monitoring technique for next generation optical access networks. A performance comparison is carried out to identify the most cost-efficient fault supervision schemes.

  • 248.
    Chen, Jiajia
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Urban, Patryk J.
    Wosinska, Lena
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Fast fault monitoring technique for reliable WDM PON: Achieving significant operational saving2013Ingår i: 2013 Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference, OFC/NFOEC 2013, IEEE , 2013, s. 6532499-Konferensbidrag (Refereegranskat)
    Abstract [en]

    We propose a fast fault supervision technique compatible with an efficient resilience scheme for WDM PON. Several drop fibres can be monitored simultaneously so that a significant reduction of operational cost can be achieved.

  • 249.
    Chen, Jiajia
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Wosinska, Lena
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Efficient Next-Generation Optical Networks: Design and Analysis of Fiber Access and Core Networks2010Bok (Refereegranskat)
    Abstract [en]

    Due to the tremendous growth of traffic volume caused by both exponential increase of number of Internet users and continual emergence of new bandwidth demanding applications, high capacity networks are required in order to satisfactorily handle the extremely large amount of traffic. Hence, optical fiber communication is the key technology for the network infrastructure. This book addresses design and analysis of access and core networks targeting important research problems, which need to be tackled for the effective realization of next-generation optical networks. We hope that this book will give the researchers and engineers who work on optical networks an overview of the current trends and contribute to a deeper understanding of problems related to next-generation optical access and wide-area networks, which have tremendous potential to increase network capacity and support the rapidly growing bandwidth demand.

  • 250.
    Chen, Jiajia
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Wosinska, Lena
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS.
    Reliable overlaid PON architecture using WDM with shared protection2010Ingår i: Optical Communication (ECOC), 2010 36th European Conference and Exhibition on, 2010, s. 1-3Konferensbidrag (Refereegranskat)
    Abstract [en]

    A novel shared protection scheme using WDM in overlaid PONs is presented and evaluated. A large number of users can be supported and connection availability higher than 99.999% can be offered at a minimum cost.

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