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  • 301.
    Damola, Ayodele
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Peer to peer networking in Ethernet broadband access networks2005Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The use of peer-to-peer (P2P) applications is growing dramatically, particularly for sharing content such as video, audio, and software. The traffic generated by these applications represents a large proportion of Internet traffic. For the broadband access network providers P2P traffic presents several problems.

    This thesis identifies the performance and business issues that P2P traffic has on broadband access networks employing the McCircuit separation technique. A mechanism for managing P2P within the access network is proposed. The P2P diversion algorithm aims to manage P2P traffic within the access network based on layer 2 and layer 3 information without employing intrusive layer 7 traffic detection. To solve the contention problem experienced by best effort traffic in the access network, a solution based on the diversion algorithm and on a QoS based traffic classification scheme is proposed. A business model defining the business roles and pricing schemes is presented based on the features offered by the P2P diversion algorithm introducing new opportunities for gaining revenue from P2P traffic for the network service providers and providing better services to users.

  • 302.
    Dan, Jurca
    et al.
    NTT DOCOMO Eurolabs in Munich, Germany.
    Stadler, Rolf
    KTH, School of Electrical Engineering (EES).
    H-GAP: Estimating Histograms of Local Variables with Accuracy Objectives for Distributed Real-Time Monitoring2010In: IEEE Transactions on Network and Service Management, ISSN 1932-4537, E-ISSN 1932-4537, Vol. 7, no 2, p. 83-95Article in journal (Refereed)
    Abstract [en]

    We present H-GAP, a protocol for continuous monitoring,which provides a management station with the valuedistribution of local variables across the network. The protocolestimates the histogram of local state variables for a givenaccuracy and with minimal overhead. H-GAP is decentralizedand asynchronous to achieve robustness and scalability, and itexecutes on an overlay interconnecting management processesin network devices. On this overlay, the protocol maintains aspanning tree and updates the histogram through incrementalaggregation. The protocol is tunable in the sense that it allowscontrolling, at runtime, the trade-off between protocol overheadand an accuracy objective. This functionality is realized throughdynamic configuration of local filters that control the flow ofupdates towards the management station. The paper includes ananalysis of the problem of histogram aggregation over aggregationtrees, a formulation of the global optimization problem, anda distributed solution containing heuristic, tree-based algorithms.Using SUM as an example, we show how general aggregationfunctions over local variables can be efficiently computed withH-GAP. We evaluate our protocol through simulation using realtraces. The results demonstrate the controllability of H-GAP ina selection of scenarios and its efficiency in large-scale networks.

  • 303.
    Dandugula, Chaitanya
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Networking for Smart Meters2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    "Smart grid" generally refers to a class of technology bringing electricity delivery systems into the 21st century, using computer-based remote control and automation. With the growing energy demand, efficient usage of the available energy resources is increasingly becoming a major issue around the world. Smart grid is a step in that direction. Research in the European Union and the United States are currently underway to modernize the existing and aging transmission grid and to streamline the usage of electricity.

    A typical electricity grid consists of two major entities - the utility company and the distribution control system (DCS). Electricity is generated at the utility company and the DCS is responsible for the distribution of electricity to individual homes/consumers. A smart meter (SM) is an electronic device that measures the electricity consumed at the consumer's premises and provides added information to the utility company. The data concentration unit (DCU) is a device acting as a communication hub collecting and encoding data from multiple smart meters in a neighborhood and forwarding the data to the utility company. The aim of this project is to design a network for securing the communication between the SM and the DCU in a smart metering network environment.

    The meter data communicated from the SM to the DCU is very sensitive and in the hands of an attacker, can reveal significant personal information about an individual. Hence it is of at most importance to protect the meter data transmitted from the SM. On the other hand the control signals transmitted from the DCU to the SM, need protection in order to thwart off unauthorized signals (i.e., an intruder can impersonate the DC and send out control signals to the SMs). Hence the SM and the DCU should be authenticated by each other and authorized and the data and/or control signals exchanged between them should be encrypted.

  • 304. Daneshtalab, M.
    et al.
    Ebrahimi, M.
    Liljeberg, P.
    Plosila, J.
    Tenhunen, Hannu
    KTH, School of Information and Communication Technology (ICT), Electronic Systems. University of Turku, Finland.
    High-performance on-chip network platform for memory-on-processor architectures2011In: 6th International Workshop on Reconfigurable Communication-Centric Systems-on-Chip, ReCoSoC 2011 - Proceedings, 2011, article id 5981509Conference paper (Refereed)
    Abstract [en]

    Three Dimensional Integrated Circuits (3D ICs) are emerging to improve existing Two Dimensional (2D) designs by providing smaller chip areas, higher performance and lower power consumption. Stacking memory layers on top of a multiprocessor layer (logic layer) is a potential solution to reduce wire delay and increase the bandwidth. To fully employ this capability, an efficient on-chip communication platform is required to be integrated in the logic layer. In this paper, we present an on-chip network platform for the logic layer utilizing an efficient network interface to exploit the potential bandwidth of stacked memory-on-processor architectures. Experimental results demonstrate that the platform equipped with the presented network interface increases the performance considerably.

  • 305.
    Dannerud, Sara
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Sårbarheter i routrar och switchar2008Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    There are a lot of different sources to information about vulnerabilities in routers and switches. The amount of information means that there is no easy way to find out which vendors are affected by vulnerabilities and what types of vulnerabilities that are found in network equipment. Thereby it is also hard to know how to protect your equipment against attacks.

    In this thesis a number of already existing vulnerabilities in router and switches are being analyzed. These vulnerabilities have been chosen by searching the National Vulnerability Database using the words “router” and “switch”. The aim of the analysis is to answer the questions who, what and why when it comes to vulnerabilities in routers and switches. The thesis describes which vendors are exposed to vulnerabilities, what types of vulnerabilities that are most common among routers and switches and why these vulnerabilities have came up. Based on this information, conclusions are drawn regarding what the user should do to avoid vulnerabilities in their equipment. The way the companies deal with vulnerabilities in their products is also described.

  • 306. Dargie, W.
    et al.
    Schill, A.
    Mochaourab, Rami
    Guan, L.
    A Topology Control Protocol for 2D Poisson Distributed Wireless Sensor Networks2009Conference paper (Refereed)
    Abstract [en]

    Topology control in a wireless sensor network is useful for ensuring that the network remains connected in the presence of nodes that exhaust their energy or become altogether dysfunctional (for whatever reasons). It also ensures that all the link that can be established are energy-efficient links and the nodes utilize their energy fairly. In this paper, we propose a fair and energy efficient topology control protocol for a two-dimensional random sensor deployment in which the nodes can estimate the distances to their neighbors and vary their transmission power accordingly. The protocol applies a neighbor eligibility metric in order to ensure a fair distribution of energy in the network. We introduce the notion of weighted relaying regions defined over the plane of a searching node to drop out inefficient links. Unlike most topology control protocols that rely on nearest neighbor approaches, we use a distance measure that is radio characteristic and channel condition dependent. We verify the performance of the protocol through simulation results on network graph properties and energy consumption.

  • 307.
    Darwis, Darwis
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Implementation and Analysis of VoIP CPE Management System using TR-0692008Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Customer Premises Equipment (CPE) management is underestimated by the CPE vendors and services providers while it is in fact one of the most important aspects to ensure the high quality of service. Many people still think CPE management is the same as network management. Thus, they use the Simple Network Management Protocol (SNMP) to manage their CPEs. However, SNMP alone was thought not to scale nor to support the provisioning of the types of services which internet services providers must support today.

    This thesis highlights the importance of CPE management, how it is implemented using the TR-069; a CPE management protocol defined by the DSL Forum, and how a management system can be used for VoIP service management, and whether a CPE should implement TR-069 or SNMP as the management system to support. In the addition, the TR-069 will be compared against the SNMP to determine which one is more suitable for CPE management. An interesting conclusion is that while TR-069 does have some advantages over SNMP for managing services rather than simply managing the device, these advantages are not a large as initially believed nor has TR-069 avoided the problem of proprietary management information which SNMP has demonstrated.

  • 308.
    Datta, Anwitaman
    et al.
    NTU Singapore.
    Buchegger, Sonja
    KTH, School of Computer Science and Communication (CSC), Theoretical Computer Science, TCS. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Vu, Le Hung
    EPFL.
    Rzadca, Krzysztof
    Warsaw University.
    Strufe, Thorsten
    TU Darmstadt.
    Decentralized Online Social Networks2010In: Handbook of Social Network Technologies and Applications / [ed] Borko Furht, Springer, 2010, p. 349-378Chapter in book (Refereed)
    Abstract [en]

    Current Online social networks (OSN) are web services run on logically centralized infrastructure. Large OSN sites use content distribution networks and thus distribute some of the load by caching for performance reasons, nevertheless there is a central repository for user and application data. This centralized nature of OSNs has several drawbacks including scalability, privacy, dependence on a provider, need for being online for every transaction, and a lack of locality. There have thus been several efforts toward decentralizing OSNs while retaining the functionalities offered by centralized OSNs. A decentralized online social network (DOSN) is a distributed system for social networking with no or limited dependency on any dedicated central infrastructure. In this chapter we explore the various motivations of a decentralized approach to online social networking, discuss several concrete proposals and types of DOSN as well as challenges and opportunities associated with decentralization.

  • 309. Daudi, M.
    et al.
    Hauge, Jannicke
    KTH, School of Technology and Health (STH). University of Bremen, Germany.
    Thoben, K. -D
    Effects of decision synchronization on trust in collaborative networks2016In: 17th IFIP WG 5.5 Working Conference on Virtual Enterprises, PRO-VE 2016, Springer-Verlag New York, 2016, p. 215-227Conference paper (Refereed)
    Abstract [en]

    In collaborative networks, individual and organizational entities encounter many disagreements over many decisions rights. These disagreements procreate conflicting preferences, which in turn, affect trustworthy amongst partners. To that end, it becomes necessary that partners assume a degree of fairness on decision rights by calibrating positions which they initially consider a final. This calibration involves synchronizing partners’ conflicting preferences to a compromise. The objective of this paper, therefore, is to analyze and evaluate the effect of both, compromised and uncompromised preferences on trust. To achieve this, a corresponding behavioral trust model is proposed and evaluated empirically using a logistics collaboration scenario. This evaluation applies a multi-agent systems simulation method. The simulation involves 360 observations with three preferences set as predictor variables. Results show that irrespective of a degree to which conflicting preferences are synchronized, a magnitude of the generated effect on trust, depends as well on other factors like transport cost and extent to which vehicles are loaded. Additionally, if other factors are kept constant, compromised preferences affects trust more positively than uncompromised ones.

  • 310.
    De Andrade, Marilet
    et al.
    KTH, School of Information and Communication Technology (ICT).
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Skubic, Björn
    Ahmed, Jawwad
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Enhanced IPACT: solving the over-granting problem in long-reach EPON2013In: Telecommunications Systems, ISSN 1018-4864, E-ISSN 1572-9451, Vol. 54, no 2, p. 137-146Article in journal (Refereed)
    Abstract [en]

    In this paper we address an issue referred to as "over-granting problem", which is inherent in the existing dynamic bandwidth allocation algorithms for Ethernet-based Passive Optical Networks (EPON), in particular when deployed for multi-threaded scheme in long-reach scenario. In order to solve this problem we design a scheme for the algorithm of Interleaved Polling with Adapted Cycle Time (IPACT) with the limited service discipline. We evaluate the proposed scheme through simulations for single-thread and double-thread cases and demonstrate that, the network performance can be significantly improved by our solution in terms of average delay, jitter, and throughput.

  • 311.
    de Carvalho, Elisabeth
    et al.
    Aalborg University.
    Bengtsson, Mats
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Leinkeit, Florian
    University of Bremen.
    Bockelmann, Carsten
    University of Bremen.
    Popovski, Petar
    Aalborg University.
    Relaying and Wireless Network Coding2016In: 5g Mobile and Wireless Communications Technology / [ed] Afif Osseiran, Jose F. Monserrat, Patrick Marsch, Cambridge University Press, 2016, p. 277-302Chapter in book (Other academic)
    Abstract [en]

    Relaying and network coding are powerful techniques that improve the performance of a cellular network, for example by extending the network coverage, by increasing the system capacity or by enhancing the wireless link reliability. This chapter focuses on relaying and wireless network coding in 5G. After reviewing the history of relaying, the key envisioned scenarios for relaying in 5G are highlighted, namely the provisioning of wireless backhaul in Ultra-Dense Networks (UDNs), for nomadic cells or for data aggregation in the context of massive machine-type communications. While full-duplex technology is slowly gaining maturity, it is expected that due to complexity reasons most relaying scenarios in 5G will be based on half-duplex devices. Therefore, finding solutions to overcome the half-duplex limitation remains critical. The chapter describes the following three key innovations for efficient half-duplex relaying:

    • By applying the principles of wireless network coding to distributed multi-way traffic, in-band relaying becomes a spectrally efficient solution for wireless backhaul in ultra-dense networks of small cells, despite conventional views.

    • Non-orthogonal multiple access techniques, as required by physical-layer network coding, are essential for increased spectral efficiency when simultaneous multi-flows are exchanged through a same relay. Here, Interleave-Division Multiple-Access (IDMA) is put forward for its ability to support flexible rate requirements.

    • Buffer-aided relaying is featured where different ways to exploit buffering are described for improved diversity and increased rates. This technique targets delay tolerant applications having high data rate requirements.

  • 312.
    de Fréin, Ruairí
    et al.
    TSSG, Waterford Institute of Technology, Waterford, Ireland.
    Olariu, Cristian
    University College Dublin.
    Song, Yuqian
    Trinity College Dublin.
    Brennan, Rob
    Trinity College Dublin.
    McDonagh, Patrick
    University College Dublin.
    Hava, Adriana
    University College Dublin.
    Thorpe, Christina
    University College Dublin.
    Murphy, John
    University College Dublin.
    Murphy, Liam
    University College Dublin.
    French, Paul
    IBM .
    Integration of QoS Metrics, Rules and Semantic Uplift for Advanced IPTV Monitoring2014In: Journal of Network and Systems Management, ISSN 1573-7705, Vol. 23, no 3, p. 1-36Article in journal (Refereed)
    Abstract [en]

    Increasing and variable traffic demands due to triple play services pose significant Internet Protocol Television (IPTV) resource management challenges for service providers. Managing subscriber expectations via consolidated IPTV quality reporting will play a crucial role in guaranteeing return-on-investment for players in the increasingly competitive IPTV delivery ecosystem. We propose a fault diagnosis and problem isolation solution that addresses the IPTV monitoring challenge and recommends problem-specific remedial action. IPTV delivery-specific metrics are collected at various points in the delivery topology, the residential gateway and the Digital Subscriber Line Access Multiplexer through to the video Head-End. They are then pre-processed using new metric rules. A semantic uplift engine takes these raw metric logs; it then transforms them into World Wide Web Consortium’s standard Resource Description Framework for knowledge representation and annotates them with expert knowledge from the IPTV domain. This system is then integrated with a monitoring visualization framework that displays monitoring events, alarms, and recommends solutions. A suite of IPTV fault scenarios is presented and used to evaluate the feasibility of the solution. We demonstrate that professional service providers can provide timely reports on the quality of IPTV service delivery using this system.

  • 313.
    de Fréin, Ruairí
    et al.
    KTH, School of Electrical Engineering (EES), Communication Networks. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Pfaff, Joel
    Amadeus SAS, Sophia Antipolis, Nice, France.
    Paré, Thomas
    Amadeus SAS, Sophia Antipolis, Nice, France.
    Enterprise Data Center Globality Measurement2015In: Proceedings - 15th IEEE International Conference on Computer and Information Technology, CIT 2015, 14th IEEE International Conference on Ubiquitous Computing and Communications, IUCC 2015, 13th IEEE International Conference on Dependable, Autonomic and Secure Computing, DASC 2015 and 13th IEEE International Conference on Pervasive Intelligence and Computing, PICom 2015, Institute of Electrical and Electronics Engineers (IEEE), 2015, Liverpool: IEEE Computer Society, 2015, p. 1861-1869Conference paper (Refereed)
    Abstract [en]

    Measurement of the globality of On-Line Transac- tion Processing (OLTP) workloads in Enterprise Data Centers is considered. Providing OLTP workload isolation (application, services and databases) for performance-sensitive enterprise workloads, so that activity in one workload cannot interfere with another, remains a challenge. We demonstrate that traditional aggregate OLTP Workload globality measurement frameworks can generate mis-leading globality measures. We propose a higher-order globality measurement framework which addresses this problem. We derive two high dimensional structured mea- surement matrices, namely a template and measurand matrix, with special spectral properties, which account for globality mea- surement 1) boundedness; 2) programmability; 3) multiplicity; 4) relativity; 5) spatial correlation and 6) the appropriate sensitivity of the measure to changes in the distribution of the workload. We demonstrate that these properties are exhibited by the new measure by ordering OLTP workloads by their globality measure. We evaluate the measure using a stochastic layered block model for data center topology and OLTP workload generation and demonstrate that it is consistent.

  • 314. De Nardis, L.
    et al.
    Di Benedetto, M. -G
    Tassetto, D.
    Bovelli, S.
    Akhtar, A.
    Holland, O.
    Thobaben, Ragnar
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Impact of mobility in cooperative spectrum sensing: Theory vs. simulation2012In: Wireless Communication Systems (ISWCS), 2012 International Symposium on, IEEE , 2012, p. 416-420Conference paper (Refereed)
    Abstract [en]

    This work addresses the problem of cooperative spectrum sensing in cognitive radio networks, focusing on the impact of mobility on performance of cooperative sensing. First, a review of the most recent results on cooperative spectrum sensing is provided, resulting in the identification of measurement correlation and frame error rate in the reporting channel as the main parameters influencing the performance of cooperative sensing schemes. Next, the paper discusses the extension of the analysis to the case of mobile sensors, and determines the set of assumptions made in existing literature when taking into account mobility in sensing. The paper moves then to remove some of such assumptions, by presenting simulation results obtained in presence of realistic models for propagation in the considered area, as well as of a realistic mobility model. A comparison between theoretical derivation and simulation results shows that correlation among measurements taken by different sensors and the selected mobility model may significantly affect the sensing performance.

  • 315.
    Debernardi, Nicolas
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Jäger,, Markus
    Laneri, Jean-Christophe
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Sraj, Malek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Lungaro, Pietro
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Services Provisioning and Terminal Cooperation in User-Deployed Networks2006In: IEEE International Symposium on Personal, Indoor, and Mobile Radio Communications workshops, ISSN 2166-9570, E-ISSN 2166-9589Article in journal (Refereed)
    Abstract [en]

    Exploiting high-speed user-deployed Access Points (APs) in public infrastructures has been proposed as one of the candidate solutions for reducing the cost of future radio access. A disadvantage is that, due to lack of deployment coordination, these types of network are likely to provide only partial coverage. For this reason, the set of services that could be successfully provided in these networks might be rather limited. In this paper we present a novel framework for modeling non-interactive " infotainment" services with different degrees of "time criticality", and utilize it for investigating the user service perception in "spotty" coverage networks. In order to hide the infrastructure sparsity to the end users, the terminals are assumed equipped with software agents that can "opportunistically" pre-fetch information, on behalf of their users. This can be done when in contact with an AP, or, through a peer-to-peer file exchange with other terminal agents that have previously accessed the same information. In this paper, for different service types, the relationship between AP density and service perception is investigated. Furthermore, the impact of peer-to-peer terminal cooperation is evaluated in respect to both infrastructure requirements and content access delay. The results show that already with moderate AP densities, user-deployed networks deliver acceptable service perception, especially for services with low time criticality. Furthermore, whenever a "critical" mass of users shares common interests, the adoption of a peer-to-peer exchange strategy brings the significant gains of infrastructure reduction and/or improved service perception.

  • 316.
    Demirel, Burak
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. University of Paderborn, Germany.
    Gupta, V.
    Quevedo, D. E.
    Johansson, Mikael
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    On the Trade-Off between Communication and Control Cost in Event-Triggered Dead-Beat Control2016In: IEEE Transactions on Automatic Control, ISSN 0018-9286, E-ISSN 1558-2523, Vol. PP, no 99, article id 7562376Article in journal (Refereed)
    Abstract [en]

    We consider a stochastic system where the communication between the controller and the actuator is triggered by a thresholdbased rule. The communication is performed across an unreliable link that stochastically erases transmitted packets. To decrease the communication burden, and as a partial protection against dropped packets, the controller sends a sequence of control commands to the actuator in each packet. These commands are stored in a buffer and applied sequentially until the next control packet arrives. In this context, we study dead-beat control laws and compute the expected linear-quadratic loss of the closed-loop system for any given event-threshold. Furthermore, we provide analytical expressions that quantify the trade-off between the communication cost and the control performance of event-triggered control systems. Numerical examples demonstrate the effectiveness of the proposed technique.

  • 317. Deng, Lei
    et al.
    Beltrán, Marta
    Pang, Xiaodan
    RISE ACREO AB.
    Zhang, Xu
    Arlunno, Valeria
    Zhao, Ying
    Caballero, Antonio
    Dogadaev, Anton
    Yu, Xianbin
    Llorente, Roberto
    Liu, Deming
    Tafur Monroy, I
    Fiber Wireless Transmission of 8.3-Gb/s/ch QPSK-OFDM Signals in 75–110-GHz Band2012In: Photonics Technology Letters, IEEE, Vol. 24, no 5, p. 383-385Article in journal (Refereed)
  • 318. Deng, Lei
    et al.
    Liu, Deming
    Pang, Xiaodan
    RISE ACREO AB.
    Zhang, Xu
    Arlunno, Valeria
    Zhao, Ying
    Caballero, Antonio
    Dogadaev, Anton K
    Yu, Xianbin
    Monroy, Idelfonso Tafur
    Beltran, Marta
    Llorente, Roberto
    42.13 Gbit/S 16qam-OFDM Photonics-Wireless Transmission in 75-110 GHz Band2012In: Progress In Electromagnetics Research, Vol. 126, p. 449-461Article in journal (Refereed)
  • 319. Deng, Lei
    et al.
    Pang, Xiaodan
    RISE ACREO AB.
    Monroy, Idelfonso Tafur
    Tang, Ming
    Shum, Ping
    Liu, Deming
    Experimental demonstration of nonlinearity and phase noise tolerant 16-QAM OFDM W-band (75–110 GHz) signal over fiber system2014In: Journal of Lightwave Technology, Vol. 32, no 8, p. 1442-1448Article in journal (Refereed)
  • 320. Deng, Lei
    et al.
    Pang, Xiaodan
    RISE ACREO AB.
    Zhang, Xu
    Yu, Xianbin
    Liu, Deming
    Monroy, Idelfonso Tafur
    Nonlinearity and Phase Noise Tolerant 75-110 GHz Signal over Fiber System Using Phase Modulation Technique2013In: National Fiber Optic Engineers Conference, 2013Conference paper (Refereed)
  • 321. Deng, Lei
    et al.
    Pang, Xiaodan
    RISE ACREO AB.
    Zhao, Ying
    Othman, M Binti
    Jensen, Jesper Bevensee
    Zibar, Darko
    Yu, Xianbin
    Liu, Deming
    Monroy, Idelfonso Tafur
    2x2 MIMO-OFDM Gigabit fiber-wireless access system based on polarization division multiplexed WDM-PON2012In: Optics express, Vol. 20, no 4, p. 4369-4375Article in journal (Refereed)
  • 322. Deng, Lei
    et al.
    Zhao, Ying
    Pang, Xiaodan
    RISE ACREO AB.
    Tang, Ming
    Shum, Ping
    Liu, Deming
    All-VCSEL Transmitters With Remote Optical Injection for WDM-OFDM-PON2014In: IEEE Photonics Technology Letters, Vol. 26, no 5, p. 461-464Article in journal (Refereed)
  • 323. Deng, Lei
    et al.
    Zhao, Ying
    Pang, Xiaodan
    RISE ACREO AB.
    Yu, Xianbin
    Jensen, J Bevensee
    Liu, Deming
    Monroy, I Tafur
    Colorless ONU based on all-VCSEL sources with remote optical injection for WDM-PON2011In: Photonics Conference (PHO), 2011 IEEE, 2011, p. 220-221Conference paper (Refereed)
  • 324. Deng, Lei
    et al.
    Zhao, Ying
    Pang, Xiaodan
    RISE ACREO AB.
    Yu, Xianbin
    Liu, Deming
    Monroy, Idelfonso Tafur
    Intra and inter-PON ONU to ONU virtual private networking using OFDMA in a ring topology2011In: Microwave Photonics, 2011 International Topical Meeting on & Microwave Photonics Conference, 2011 Asia-Pacific, MWP/APMP, 2011, p. 176-179Conference paper (Refereed)
  • 325.
    Derakhshanno, Homayoun
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Voice over IP over GPRS2008Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Voice over IP (VoIP) technology has become prevalent today due to its lower cost than traditional telephony and its ability to support new value-added services. Additionally, the increasing availability of wireless internet access has led to research studies examining the combination of wireless network access with voice over IP. With the widespread availability of advanced mobile phones and Pocket PCs, the need for VoIP applications on these mobile platforms is tangible. To enable this, we need to evaluate the current wireless access technologies to see if they can support the necessary traffic and implement software to offer these VoIP services to users.

    In order to easily implement an IP-based service on GSM technology, we should use the GPRS service provided by the GSM operators. In this thesis, we evaluate Voice over IP service over GPRS in terms of feasibility and quality. Following this we ported a locally developed VoIP program to a Pocket PC (with GSM SIM-card support) which runs Microsoft’s Windows Mobile in order to provide suitable software as needed to offer the service from such a portable device.

  • 326. Dethise, A.
    et al.
    Chiesa, Marco
    Université catholique du Louvain, Belgium.
    Canini, M.
    Privacy-preserving detection of inter-domain SDN rules overlaps2017In: SIGCOMM Posters and Demos 2017 - Proceedings of the 2017 SIGCOMM Posters and Demos, Part of SIGCOMM 201722 August 2017, Association for Computing Machinery (ACM), 2017, p. 6-8Conference paper (Refereed)
    Abstract [en]

    SDN approaches to inter-domain routing promise better traffic engineering, enhanced security, and higher automation. Yet, naïve deployment of SDN on the Internet is dangerous as the control-plane expressiveness of BGP is significantly more limited than the data-plane expressiveness of SDN, which allows fine-grained rules to deflect traffic from BGP's default routes. This mismatch may lead to incorrect forwarding behaviors such as forwarding loops and blackholes, ultimately hindering SDN deployment at the inter-domain level. In this work, we make a first step towards verifying the correctness of inter-domain forwarding state with a focus on loop freedom while keeping private the SDN rules, as they comprise confidential routing information. To this end, we design a simple yet powerful primitive that allows two networks to verify whether their SDN rules overlap, i.e., the set of packets matched by these rules is non-empty, without leaking any information about the SDN rules. We propose an efficient implementation of this primitive by using recent advancements in Secure Multi-Party Computation and we then leverage it as the main building block for designing a system that detects Internet-wide forwarding loops among any set of SDN-enabled Internet eXchange Points.

  • 327. Devlic, Alisa
    Extending CPL with context ontology2006Conference paper (Refereed)
    Abstract [en]

    Communication has always been an essential part of peo-ple's everyday life. Nowadays most of people would liketo be reachable on multiple devices at anytime, anyplace. As a consequence, there has been a need to know and exploit a user's availability for communication (so called presence information), so that he/she can control incoming callsand make the decision to accept this call or not based onthe user's current context. The appearance and acceptanceof Session Initiation Protocol (SIP) as a signalling protocol for next generation networks has opened the door for multiple services, such as Voice over IP (VoIP), chat, games,instant messaging, and other innovative communication services. Built on top of existing data communication networks, this has enabled easy integration of voice and data services. In this paper we present an idea on how to use the context information to enhance the power of existing SIP call control services, to enable users to have greater control over their incoming/outgoing calls. These services are implemented using Call Processing Language (CPL), a language to describe and control Internet Telephony Services. They are extended with context parameters to permit context-based decision making based on context ontology. We want to show how easy is to add new context parameters to the CPL and how complex criteria can be built using our solution.

  • 328.
    Devlic, Alisa
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    On Optimization of Quality of User Experience and Wireless Network Bandwidth in Video Content Delivery2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Mobile video content today generates more than half of the mobile data traffic.The increasing popularity of mobile video on demand services poses great challenges to mobile operators and content providers. Frontmost, how to reduce the mobile video traffic load, while delivering high quality video content to mobile users without perceived quality degradations for the same (or cheaper) price? Battery lifetime represents another key factor of a user’s Quality of Experience(QoE). A lot of device energy is consumed by mobile network signalling and data transmission over new generation mobile communication systems. This thesis focuses on: (1) reducing the size of the video that is delivered to the enduser in the maximum achievable video quality, thus optimizing the wireless network bandwidth and the user-perceived QoE, and (2) reducing the energy consumption of a mobile device that is associated to data transfer over the radio interface, thus increasing the device’s battery lifetime. The main contributions have been given in providing the Over-the-Top video optimization and delivery schemes and recommendations on tuning their parameters in order to minimize the bandwidth and energy consumption of mobile video delivery, while maximizing the predictable user-perceived QoE. By preventing the video to be prefetched on low data rates and tuning the datarate threshold according to statistical properties of available data rates, we show that 20-70% of energy cost can be reduced by opportunistic prefetching, depending on the user’s pattern of available data rates. The data rate values ordered in time that have a large amount of serial correlation and low noise variance, or low average valueand high peak-to-mean ratio, are likely to yield the highest energy gains from content prefetching. Moreover, we show that energy gains are the largest when the threshold data rate is set close to an average data rate, due to the highest availability of data rates around this value, and for longer sleep time between the prefetching periods, which increases the probability of moving away from the areas with low data rates. Next, we focus on QoE-aware mobile video delivery solutions that are more bandwidth efficient without compromising the user-perceived video quality. They deliver a video over a varying data rate channel that is optimized for viewing on a mobile device in the highest perceptual video quality that can be achieved in the given video and network conditions. An optimized video consists of short segments in the minimum resolutions that satisfy the target perceptual video quality and have up to 60% reduced size compared to the video in the corresponding fixed video resolution, without perceptible quality difference. The delivery is performed by on demand download, context-aware prefetching, or in real time using the QoE-aware adaptive video streaming that runs over Dynamic Adaptive video Streaming over HTTP (DASH). By limiting the maximum bitrates of the requested video segments and using the remaining throughput to prefetch optimized video segments in advance of playout, we show that QoE-aware adaptive video streaming maintains a more stable perceptual video quality than DASH despite the fluctuations of the channel bandwidth, while using fewer number of bits, which improves a user-perceived QoE. The results of this thesis can help operators and content providers to reduce their costs and provide more content to their users at the same (or cheaper) price.

  • 329. Devlic, Alisa
    et al.
    Erik, Klintskog
    Context retrieval and distribution in a mobile distributed environment2007Conference paper (Refereed)
    Abstract [en]

    Context-aware services are gaining momentum in mobile computing. To enable rapid development of context-aware services,context information has to be retrieved from the environment, modeled,processed, and distributed to these services. MIDAS is a European research project concerning 3G and beyond, which aims to dene and implement a platform to simplify and speed up the task of developing and deploying mobile applications and services. MIDAS context engine provides mechanisms to retrieve, model, synthesize, and distribute context information in a distributed, mobile environment. This paper presents a way to retrieve and distribute context information using context queries and triggers. A novel approach to perform context synthesis will be presented using operators.

  • 330.
    Devlic, Alisa
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Graf, A.
    Barone, P.
    Evaluation of context distribution methods via Bluetooth and WLAN: Insights gained while examining Battery Power Consumption2008In: MobiQuitous 2008 - 5th International ICST Conference on Mobile and Ubiquitous Systems: Computing, Networking and Services, 2008Conference paper (Refereed)
    Abstract [en]

    In a traditional context-aware system, most context information is local to a device. However, we may need access to context information from outside the device. Increasingly mobile electronic devices are equipped with Bluetooth and/or WLAN network interfaces. Both of these technologies enable ad hoc discovery & networking. In this paper we evaluate the use of these technologies for context distribution within a local area (i.e., limited to a single hop). Using Bluetooth, we begin by discovering devices using Bluetooth's discovery protocol, collect their context information, create an XML file containing this information, and distribute this file to all discovered devices, such that every device now has the same context information. Next we perform the same discovery, collect, and distribute functions, but using WLAN. In each case we have performed the cycle of operations starting with a fully charged battery and continuing until the device was not able to utilize the selected wireless interface any longer. Finally we compare both approaches to context distribution in terms of battery power consumption. We observe that Bluetooth consumes 2-6 times more energy for transmission of a 1MB file to two devices than to discover these two devices. Furthermore, the transfer of this file is two times slower than WLAN, and we must unicast this file to each device. Multicasting via WLAN proved to be less energy consuming than the Bluetooth transmission, if data is to be sent to more than three users. In addition, the energy to discover 2 devices along with their services using Bluetooth consumed 52 times more energy than to receive the same amount of data via a WLAN multicast. Thus, this paper shows that it is more energy efficient to distribute context knowledge to other devices, than having each device learn this information itself. Finally, we give equations for calculating the battery power consumption of transmitting data using any protocol that runs over Bluetooth or over WLAN.

  • 331.
    Devlic, Alisa
    et al.
    Ericsson Research.
    John, Wolfgang
    Ericsson Research.
    Sköldström, Pontus
    A use-case based analysis of network management functions in the ONF SDN model2012In: European Workshop on SDN, 2012Conference paper (Refereed)
    Abstract [en]

    The concept of software-defined networking (SDN) recently gained huge momentum in the industry, driven mainly by IT companies interested in data center applications. In this paper, however, we apply SDN to the carrier domain, which poses additional requirements in terms of network management functions. As a specific use-case we take a virtualized carrier network shared by multiple customers. We consider the current SDN model as defined by the Open Networking Foundation (ONF), including the OpenFlow and OF-config protocols. Through a step-by-step discussion of the rocedures required to configure and manage the virtualized network, we analyze the applicability of the current SDN model as specified by the ONF. As a result, we identify shortcomings and propose necessary extensions to the ONF SDN model. The highlighted extensions include control network bootstrapping considerations, updates to the SDN and NOS model, and most importantly extensions of the OF-config management data model

  • 332.
    Devlic, Alisa
    et al.
    Ericsson Research.
    John, Wolfgang
    Ericsson Research.
    Sköldström, Pontus
    Carrier-grade Network Management Extensions to the SDN Framework2012In: 8th Swedish National Computer Networking Workshop SNCNW 2012 Stockholm, 2012Conference paper (Refereed)
    Abstract [en]

    The concept of software-defined networking (SDN)recently  gained  huge  momentum  in  the  industry,  driven  mainlyby  IT  companies  interested  in  datacenter  applications.  In  thispaper, however, we consider SDN applied in the carrier domain,which poses additional requirements on the network architecture,including  network  management  functions.  We  derive  concreterequirements  for  the  use-case  of  a  virtualized  multi-provideraccess/aggregation  network  based  on  carrier-grade  SDN.  Wethen provide initial architectural considerations for integrationof  network  management  extensions  to  the  SDN  framework  asdefined  by  the  Open  Networking  Foundation  (ONF).  Architec-tural considerations include definition of the required entities andtheir interactions. Finally, we apply the proposed architecture onthe access/aggregation network use-case, outlining procedures ofhow  the  network  management  extensions  can  enable  networkwide and node specific management & configuration

  • 333.
    Devlic, Alisa
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    Kamaraju, Pavan
    Lungaro, Pietro
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    Segall, Zary
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    Tollmar, Konrad
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    QoE-aware optimization for video delivery and storage2015In: 2015 IEEE 16th International Symposium on "A World of Wireless, Mobile and Multimedia Networks" (WoWMoM) 2015, Boston, MA, USA, 2015, p. 1-10Conference paper (Refereed)
    Abstract [en]

    The explosive growth of Over-the-top (OTT) online video strains capacity of operators’ networks, which severely threatens video quality perceived by end users. Since video is very bandwidth consuming, its distribution costs are becoming too high to scale with network investments that are required to support the increasing bandwidth demand. Content providers and operators are searching for solutions to reduce this video traffic load, without degrading their customers’ perceived Quality ofExperience (QoE). This paper proposes a method that can programmatically optimize video content for desired QoE accordingto perceptual video quality and device display properties, while achieving bandwidth and storage savings for content providers, operators, and end users. The preliminary results obtained with Samsung Galaxy S3 phone show that up to 60% savings can be achieved by optimizing movies without compromising the perceptible video quality, and up to 70% for perceptible, but not annoying video quality difference. Tailoring video optimization to individual user perception can provide seamless QoE delivery across all users, with a low overhead (i.e., 10%) required to achieve this goal. Finally, two applications of video optimization: QoE-aware delivery and storage, are proposed and examined.

  • 334.
    Devlic, Alisa
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    Kamaraju, Pavan
    Lungaro, Pietro
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    Segall, Zary
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    Tollmar, Konrad
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    Towards QoE-aware adaptive video streaming2016In: 2015 IEEE 23rd International Symposium on Quality of Service (IWQoS), IEEE, 2016, p. 75-76, article id 7404713Conference paper (Refereed)
    Abstract [en]

    This paper describes a novel QoE-aware adaptive video streaming method that enhances the viewing experience on mobile devices and reduces cellular network bandwidth consumed by Dynamic Adaptive Streaming over HTTP (DASH) by considering perceptual video quality and data rate channel conditions in the bitrate adaptation process. By streaming an optimized video for the particular video quality and channel conditions toa mobile device, we can improve the worst video qualities causedby DASH streaming and reduce quality variations using fewer number of bits.

  • 335.
    Devlic, Alisa
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab).
    Lungaro, Pietro
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Segall, Zary
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Tollmar, Konrad
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Mobile Service Laboratory (MS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Evaluation of energy profiles for mobile video prefetching in generalized stochastic access channels2014In: Mobile and Ubiquitous Systems: Computing, Networking, and Services: 10th International Conference, MOBIQUITOUS 2013, Tokyo, Japan, December 2-4, 2013, Revised Selected Papers, Springer, 2014, p. 209-223Conference paper (Refereed)
    Abstract [en]

    This paper evaluates the energy cost reduction of Over-The-Top mobile video content prefetching in various network conditions. Energy cost reduction is achieved by reducing the time needed to download content over the radio interface by prefetching data on higher data rates, compared to the standard on demand download. To simulate various network conditions and user behavior, a stochastic access channel model was built and validated using the actual user traces. By changing the model parameters, the energy cost reduction of prefetching in different channel settings was determined, identifying regions in which prefetching is likely to deliver the largest energy gains. The results demonstrate that the largest gains (up to 70%) can be obtained for data rates with strong correlation and low noise variation. Additionally, based on statistical properties of data rates, such as peak-to-mean and average data rate, prefetching strategy can be devised enabling the highest energy cost reduction that can be obtained using the proposed prefetching scheme.

  • 336.
    Dhainaut, Guillaume
    KTH, School of Electrical Engineering (EES), Communication Networks.
    A reverse proxy for VoIP: Or how to improve security in a ToIP network2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The need for security is crucial in Telephony over IP (ToIP). Secure protocols have been designed as well as specific devices to fulfill that need. This master thesis examines one of such devices called Session Border Controller (SBC), which can be compared to reverse proxies for ToIP. The idea is to apply message filters to increase security.

    This thesis presents the reasons of SBC existence, based on the security weaknesse sa ToIP network can show. These reasons are then used to establish a list of features which can be expected from a SBC and discuss its ideal placement in a ToIP network architecture. A test methodology for SBCs is established and used on the free software Kamailio as an illustration. Following this test, improvements of this software, regarding threats prevention and attacks detection, are presented and implemented.

  • 337. Dhaou, I. B.
    et al.
    Kondoro, A.
    Kelati, A.
    Rwegasira, D. S.
    Naiman, S.
    Mvungi, N. H.
    Tenhunen, H.
    Communication and security technologies for smart grid2017In: International Journal of Embedded and Real-Time Communication Systems, ISSN 1947-3176, E-ISSN 1947-3184, Vol. 8, no 2, p. 40-65Article in journal (Refereed)
    Abstract [en]

    The smart grid is a new paradigm that aims to modernize the legacy power grid. It is based on the integration of ICT technologies, embedded system, sensors, renewable energy and advanced algorithms for management and optimization. The smart grid is a system of systems in which communication technology plays a vital role. Safe operations of the smart grid need a careful design of the communication protocols, cryptographic schemes, and computing technology. In this article, the authors describe current communication technologies, recently proposed algorithms, protocols, and architectures for securing smart grid communication network. They analyzed in a unifying approach the three principles pillars of smart-gird: Sensors, communication technologies, and security. Finally, the authors elaborate open issues in the smart-grid communication network.

  • 338. Di Giglio, A.
    et al.
    Schiano, M.
    Ruffini, M.
    Payne, D.
    Doran, N.
    Achouche, M.
    Jensen, R.
    O’Sullivan, B.
    Pfeiffer, T.
    Bonk, R.
    Rohde, H.
    Talli, G.
    Yin, X.
    Wessaly, R.
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Montalvo, J.
    Towards the distributed core for ubiquitous superfast broadband optical access2014In: 2014 European Conference on Networks and Communications (EuCNC), 2014, p. 1-5Conference paper (Refereed)
    Abstract [en]

    In this paper, we describe recent architectural and technological advances of the end to end optical network architecture proposed by the DISCUS project (the DIStributed Core for unlimited bandwidth supply for all Users and Services). The two main targets of DISCUS are the principle of equivalence in the access and the reduction of optical-to-electronic conversions in the metro-core network. Technological advances and techno-economic evaluation of Long-Reach Passive Optical Networks (LR-PON), as well as the optimal metro-core node architecture and the required network control plane framework are reported. Network infrastructure sharing challenges are also discussed.

  • 339.
    Di Marco, Piergiuseppe
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. Ericsson Research, Sweden.
    Athanasiou, Georgios
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. Institute of Communications and Computer Systems, National Technical University of Athens, Greece.
    Mekikis, Prodromos
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. Signal Theory and Communications Dept., Technical University of Catalonia, Barcelona, Spain.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    MAC-aware routing metrics for the internet of things2015In: Computer Communications, ISSN 0140-3664, E-ISSN 1873-703XArticle in journal (Refereed)
    Abstract [en]

    The development of the internet of things (IoT) has significantly affected the concept of wireless networking. As the number of wireless devices is rising, new medium access control (MAC) and routing protocols have been developed to guarantee end-to-end network performance. When existing layered solutions are stacked together, there might be detrimental effects on the overall network performance. In this paper, an analysis of MAC and routing protocols for IoT is provided with focus on the IEEE 802.15.4 MAC and the IETF RPL standards. It is shown that existing routing metrics do not account for the complex interactions between MAC and routing, and thus novel metrics are proposed. This enables a protocol selection mechanism for selecting the routing option and adapting the MAC parameters, given specific performance constraints. Extensive analytical and experimental results show that the behavior of the MAC protocol can hurt the performance of the routing protocol and vice versa, unless these two are carefully optimized together by the proposed method.

  • 340.
    Di Marco, Piergiuseppe
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Fischione, Carlo
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Santucci, F.
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Effects of Rayleigh-lognormal fading on IEEE 802.15.4 networks2013In: Communications (ICC), 2013 IEEE International Conference on, IEEE conference proceedings, 2013, p. 1666-1671Conference paper (Refereed)
    Abstract [en]

    The IEEE 802.15.4 communication protocol is a de-facto standard for wireless applications in industrial and home automation. Although the performance of the medium access control (MAC) of the IEEE 802.15.4 has been thoroughly investigated under the assumption of ideal wireless channel, there is still a lack of understanding of the cross-layer interactions between MAC and physical layer in the presence of realistic wireless channel models that include path loss, multi-path fading and shadowing. In this paper, an analytical model of these dynamics is proposed. The analysis considers simultaneously a composite Rayleigh-lognormal channel fading, interference generated by multiple terminals, the effects induced by hidden terminals, and the MAC reduced carrier sensing capabilities. It is shown that the reliability of the contention-based MAC over fading channels is often far from that derived under ideal channel assumptions. Moreover, it is established to what extent fading may be beneficial for the overall network performance.

  • 341.
    Di, Shuang
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    USB Attached Network Performance: Uplink Performance2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    More and more people all over the world are using a USB modem to connect to the Internet. This is especially true in Sweden- which has the highest 3G coverage in Europe. Comparable to fixed broadband access, using a 3G USB modem is a wonderful experience for the customer. Increasingly, anywhere we can use our cellular phone is a place that we are able to access the Internet, even if we are traveling in a train, walking in a park, or sitting on the beach. This makes working on the move much easier. However, customers do not know if the network throughput, delay, and the cost of connectivity match their needs. Additionally, there is also the question of the time to connect to the network when there has not been some traffic for a period of time. However, the throughput, delay, and "time to connect" when using such a modem to connect to a wireless network depend on several factors. In this thesis we will examine these factors. More specifically, the thesis will analyze in detail the effects of using a USB attached network interface, in order to gain greater understanding of such an interface’s network performance. We have chosen to focus on the uplink, as it was expected to have a low throughput and it has not had as much attention as the downlink performance.

  • 342. Dietzel, C.
    et al.
    Antichi, G.
    Castro, I.
    Fernandes, E. L.
    Chiesa, Marco
    Université catholique du Louvain.
    Kopp, D.
    SDN-enabled traffic engineering and advanced blackholing at IXPs2017In: SOSR 2017 - Proceedings of the 2017 Symposium on SDN Research, 2017, p. 181-182Conference paper (Refereed)
    Abstract [en]

    While the clean slate approach proposed by Software Defined Networking (SDN) promises radical changes in the stagnant state of network management, SDN innovation has not gone beyond the intra-domain level. For the inter-domain ecosystem to benefit from the advantages of SDN, Internet Exchange Points (IXPs) are the ideal place: a central interconnection hub through which a large share of the Internet can be affected. In this demo, we showcase the ENDEAVOUR platform: a new software defined exchange approach readily deployable in commercial IXPs. We demonstrate here our implementations of traffic engineering and Distributed Denial of Service mitigation, as well as how member networks cash in on the advanced SDN-features of ENDEAVOUR, typically not available in legacy networks.

  • 343.
    Dimitriou, Eleftherios
    KTH, Superseded Departments, Teleinformatics.
    An Archive Robot for Video Mail1998Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Today most of the real-time voice communications are carried over the Plain Old Telephone System (POTS). In the future that might well change. Research indicates a strong interest for developing the network to support real-time communications in a satisfactory way. Applications will be needed in this new world of IP (Internet Protocol) based communications.

    In this thesis we present an application called the Video Mail service. The Video Mail service can record and playback audio and video messages over the Internet using standard Internet telephony protocols. It is built on top of a more general platform called the Archive Robot. The Archive Robot provides the real-time functionality of the system. It is not explicitly designed to support the Video Mail service. Other services such as Conference Tool and Interactive Voice Response can also be supported.

    The Video Mail service was designed and implemented. Furthermore, this first prototype was used to evaluate the performance of the overall system.

  • 344.
    Dinc, Ergin
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Vondra, Michal
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Multi-user Beamforming and Ground Station Deployment for 5G Direct Air-to-Ground Communication2017In: Globecom 2017 - 2017 IEEE Global Communications Conference, Institute of Electrical and Electronics Engineers (IEEE), 2017Conference paper (Refereed)
    Abstract [en]

    On-board of aircraft is one of the last venues without high-speed connectivity, which makes it an important problem to address for both industry and academia. To this end, direct air-to-ground communications (DA2GC), where communication link is provided via direct link between aircraft and ground station, is a promising solution to provide high capacity and low latency backhaul capacity for aircraft. In this paper, we investigate the ground station deployment problem to provide 1.2 Gbps average backhaul capacity for each aircraft. The feasible operation points for the key network parameters: the number of ground stations, antenna array size, transmit power and bandwidth, are calculated. In addition, we propose a multi-user beamforming algorithm for dual-polarized hybrid DA2GC antenna arrays, and derive a tractable expression for the DA2GC cell throughput.

  • 345. Ding, Zhiguo
    et al.
    Krikidis, Ioannis
    Rong, Beiyu
    Thompson, John S.
    Wang, Chao
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Yang, Sheng
    On Combating The Half-Duplex Constraint In Modern Cooperative Networks: Protocols And Techniques2012In: IEEE wireless communications, ISSN 1536-1284, E-ISSN 1558-0687, Vol. 19, no 6, p. 20-27Article in journal (Refereed)
    Abstract [en]

    A key issue that characterizes cooperative wireless networks is the half-duplex constraint (HDC), which refers to the inability of current modems to receive and transmit data in the same frequency at the same time. This hardware limitation results in inefficient use of system resources (bandwidth loss) as it requires dedicated bandwidth allocation for relay transmissions. Methods to overcome the HDC have been studied intensively in the literature of cooperative networks in recent years, and several approaches have been proposed. In this article we highlight four different techniques which combat the HDC by using existing technology. The first approach is non-orthogonal protocols, which allow the source to be active during relay transmissions. The second approach is the overlap of several relaying transmissions in order to mimic an ideal full-duplex operation. The third solution is the two-way relay channel where two sources exchange data via the assistance of a shared relay. Finally, the fourth approach incorporates cooperation on the "network" level and uses the cognitive radio concept to enable relay transmissions during silent periods of source terminals. These techniques summarize some of the most significant HDC solutions that cover both the physical and network layers.

  • 346. Dixit, A.
    et al.
    Lannoo, B.
    Colle, D.
    Pickavet, M.
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Mahloo, Mozhgan
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Efficient protection schemes for hybrid WDM/TDM Passive Optical Networks2012In: Communications (ICC), 2012 IEEE International Conference on, IEEE , 2012, p. 6220-6224Conference paper (Refereed)
    Abstract [en]

    Hybrid WDM/TDM Passive Optical Network (PON) is a promising candidate for next-generation optical access (NGOA) solutions as it is able to offer a high splitting ratio and consequently achieves a relatively low cost and power consumption on a per-user basis compared with other NGOA architectures. On the other hand, the end users require a certain level of connection availability while the operators need to reduce the failure impact (i.e. to avoid a huge number of end users being affected by any single failure). Therefore, by evaluating the connection availability and failure impact robustness we identify the most efficient parts to provide resilience in a hybrid WDM/TDM PON from an operator and an end-user perspective. Then, we select the appropriate protection schemes to construct some novel reliable architectures and analyze their reliability performance in urban and rural scenarios. In this way, this paper provides a comprehensive insight into the most relevant protection mechanisms for hybrid WDM/TDM PONs.

  • 347. Dixit, A.
    et al.
    Mahloo, Mozhgan
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Lannoo, B.
    Chen, Jiajia
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Wosinska, Lena
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).
    Colle, D.
    Pickavet, M.
    Protection strategies for Next Generation Passive Optical Networks -22014In: 2014 International Conference on Optical Network Design and Modeling, 2014, p. 13-18Conference paper (Refereed)
    Abstract [en]

    Next Generation Passive Optical Networks-2 (NG-PON2) are being considered to upgrade the current PON technology to meet the ever increasing bandwidth requirements of the end users while optimizing the network operators’ investment. Reliability performance of NG-PON2 is very important due to the extended reach and, consequently, large number of served customers per PON segment. On the other hand, the use of more complex and hence more failure prone components than in the current PON systems may degrade reliability performance of the network. Thus designing reliable NG-PON2 architectures is of a paramount importance. Moreover, for appropriately evaluating network reliability performance, new models are required. For example, the commonly used reliability parameter, i.e., connection availability, defined as the percentage of time for which a connection remains operable, doesn’t reflect the network wide reliability performance. The network operators are often more concerned about a single failure affecting a large number of customers than many uncorrelated failures disconnecting fewer customers while leading to the same average failure time. With this view, we introduce a new parameter for reliability performance evaluation, referred to as the failure impact. In this paper, we propose several reliable architectures for two important NG-PON2 candidates: wavelength division multiplexed (WDM) PON and time and wavelength division multiplexed (TWDM) PON. Furthermore, we evaluate protection coverage, availability, failure impact and cost of the proposed schemes in order to identify the most efficient protection architecture.

  • 348.
    Do, Tan Tai
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Oechtering, Tobias J.
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory.
    Optimal Transmission for the MIMO Bidirectional Broadcast Channel in the Wideband Regime2013In: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 61, no 20, p. 5103-5116Article in journal (Refereed)
    Abstract [en]

    This paper considers a transmit strategy for an AWGN MIMO bidirectional broadcast channel in the wideband regime. In order to characterize the boundaries of the wideband capacity and energy per bit regions, the transmit strategy at the relay is designed to maximize the weighted wideband rate sum. A closed form of the optimal transmit covariance matrix is derived, which shows that a single beam transmit strategy is optimal. The transmit strategies for some special cases are also analyzed. The fairness versus energy efficiency tradeoff is then discussed. In addition, an extension to multipair MIMO bidirectional broadcast channel is studied in which we show that serving a certain pair with full power is optimal in the sense of maximizing the achievable weighted wideband rate sum. Finally, a discussion on the conjecture of the minimum energy per bit for multi-pair systems is provided.

  • 349.
    Do, Tan Tai
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Oechtering, Tobias
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Achievable energy per bit for the multi-pair MIMO bidirectional broadcast channel2012In: European Wireless, 2012. EW. 18th European Wireless Conference, 2012Conference paper (Refereed)
    Abstract [en]

    This paper presents a transmit strategy for the AWGN multi-pair MIMO bidirectional broadcast channels in the wideband regime. An achievable wideband rate region and an achievable energy per bit region are provided. The transmit covariance matrix at the relay has been designed in order to maximize the wideband weighted rate sum. A closed form of the optimal matrix is derived, which shows that a single beam transmit strategy is optimal. In addition, an energy efficiency versus fairness analysis is considered. Lastly, some discussions on the minimum energy per bit are given.

  • 350.
    Do, Tan Tai
    et al.
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Oechtering, Tobias
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Skoglund, Mikael
    KTH, School of Electrical Engineering (EES), Communication Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Optimal transmission for the MIMO bidirectional broadcast channel in the wideband regime2011In: IEEE Workshop on Signal Processing Advances in Wireless Communications, SPAWC, 2011, p. 356-360Conference paper (Refereed)
    Abstract [en]

    This paper presents an optimal transmit strategy for multiple antennas bidirectional broadcast channels in the wideband regime. The transmit covariance matrix at the relay has been designed in order to maximize the wideband weighted sum rate. A closed form of the optimal matrix is derived, which shows that a single beam transmit strategy is optimal. The transmit strategies for some special cases, the wideband capacity region, and the minimum energy per bit versus fairness issues are also discussed.

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