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  • 1.
    Abad Caballero, Israel Manuel
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Secure Mobile Voice over IP2003Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Voice over IP (VoIP) can be defined as the ability to make phone calls and to send faxes (i.e., to do everything we can do today with the Public Switched Telephone Network, PSTN) over IP−based data networks with a suitable quality of service and potentially a superior cost/benefit ratio. There is a desire to provide (VoIP) with the suitable security without effecting the performance of this technology. This becomes even more important when VoIP utilizes wireless technologies as the data networks (such as Wireless Local Area Networks, WLAN), given the bandwidth and other constraints of wireless environments, and the data processing costs of the security mechanisms. As for many other (secure) applications, we should consider the security in Mobile VoIP as a chain, where every link, from the secure establishment to the secure termination of a call, must be secure in order to maintain the security of the entire process.

    This document presents a solution to these issues, providing a secure model for Mobile VoIP that minimizes the processing costs and the bandwidth consumption. This is mainly achieved by making use of high− throughput, low packet expansion security protocols (such as the Secure Real−Time Protocol, SRTP); and high−speed encryption algorithms (such as the Advanced Encryption Standard, AES).

    In the thesis I describe in detail the problem and its alternative solutions. I also describe in detail the selected solution and the protocols and mechanisms this solution utilizes, such as the Transport Layer Security (TLS) for securing the Session Initiation Protocol (SIP), the Real−Time Protocol (RTP) profile Secure Real−Time Protocol (SRTP) for securing the media data transport , and the Multimedia Internet KEYing (MIKEY) as the key−management protocol. Moreover, an implementation of SRTP, called MINIsrtp, is also provided. The oral presentation will provide an overview of these topics, with an in depth examination of those parts which were the most significant or unexpectedly difficult.

    Regarding my implementation, evaluation, and testing of the model, this project in mainly focused on the security for the media stream (SRTP). However, thorough theoretical work has also been performed and will be presented, which includes other aspects, such as the establishment and termination of the call (using SIP) and the key−management protocol (MIKEY).

  • 2.
    Abbas, Haider
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Magnusson, Christer
    KTH, School of Information and Communication Technology (ICT), Computer and Systems Sciences, DSV.
    Yngström, Louise
    KTH, School of Information and Communication Technology (ICT), Computer and Systems Sciences, DSV.
    Hemani, Ahmed
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Analyzing IT Security Evaluation needs for Developing Countries2009In: IPID Annual Workshop 2009, Orebro, Sweden, 2009Conference paper (Other academic)
  • 3. Abdi, Y.
    et al.
    Derakhshandeh, J.
    Hashemi, P.
    Mohajerzadeh, S.
    Karbassian, F.
    Nayeri, F.
    Arzi, E.
    Robertson, M. D.
    Radamson, Henry H.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Light-emitting nano-porous silicon structures fabricated using a plasma hydrogenation technique2005In: Materials Science and Engineering B: Solid-State Materials for Advanced Technology, ISSN 0921-5107, Vol. 124-125, no SUPPL., 483-487 p.Article in journal (Refereed)
    Abstract [en]

    The preparation of porous silicon films by DC-plasma hydrogenation and subsequent annealing of amorphous silicon films on silicon and glass substrates is reported for the first time. The effects of varying plasma power and annealing temperatures have been investigated and characterized by scanning-electron microscopy, transmission-electron microscopy, and photoluminescence. A plasma density of about 5.5 W/m2 and hydrogenation-annealing temperatures of about 400 °C was found to be suitable for the formation of nano-crystalline silicon films with grain diameters of the order of 3-10 nm. The intensity and wavelength of the emitted visible light were found to depend on the hydrogenation and annealing conditions, and patterning of the silicon films using standard lithography allowed the creation of light-emitting patterns.

  • 4.
    Adam, Constantin
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Stadler, Rolf
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    A Middleware Design for Large-scale Clusters offering Multiple Services2006In: IEEE Transactions on Network and Service Management, ISSN 1932-4537, Vol. 3, no 1, 1-12 p.Article in journal (Refereed)
    Abstract [en]

    We present a decentralized design that dynamically allocates resources to multiple services inside a global server cluster. The design supports QoS objectives (maximum response time and maximum loss rate) for each service. A system administrator can modify policies that assign relative importance to services and, in this way, control the resource allocation process. Distinctive features of our design are the use of an epidemic protocol to disseminate state and control information, as well as the decentralized evaluation of utility functions to control resource partitioning among services. Simulation results show that the system operates both effectively and efficiently; it meets the QoS objectives and dynamically adapts to load changes and to failures. In case of overload, the service quality degrades gracefully, controlled by the cluster policies.

  • 5.
    Adam, Constantin
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Stadler, Rolf
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Adaptable Server Clusters with QoS Objectives2005In: Integrated Network Management IX - MANAGING NEW NETWORKED WORLDS / [ed] Clemm A, Festor O, Pras A, New York: IEEE , 2005, 149-163 p.Conference paper (Refereed)
    Abstract [en]

    We present a decentralized design for a server cluster that supports a single service with response time guarantees. Three distributed mechanisms represent the key elements of our design. Topology construction maintains a dynamic overlay of cluster nodes. Request routing directs service requests towards available servers. Membership control allocates/releases servers to/from the cluster, in response to changes in the external load. We advocate a decentralized approach, because it is scalable, fault-tolerant, and has a lower configuration complexity than a centralized solution. We demonstrate through simulations that our system operates efficiently by comparing it to an ideal centralized system. In addition, we show that our system rapidly adapts to changing load. We found that the interaction of the various mechanisms in the system leads to desirable global properties. More precisely, for a fixed connectivity c (i.e., the number of neighbors of a node in the overlay), the average experienced delay in the cluster is independent of the external load. In addition, increasing c increases the average delay but decreases the system size for a given load. Consequently, the cluster administrator can use c as a management parameter that permits control of the tradeoff between a small system size and a small experienced delay for the service.

  • 6.
    Adam, Constantin
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Stadler, Rolf
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Externally Controllable, Self-Oganizing Server Clusters2005In: Designing a Scalable, Self-organizing Middleware for Server Clusters (NGNM05): in the scope of Networking 2005, 2005, 1-12 p.Chapter in book (Other academic)
  • 7. Aggerstam, Thomas
    et al.
    Lovqvist, Anita
    Stevens, Renaud
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Jonsson, Stefan
    Marcks von Würtemberg, Richard
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Dubois, Mardjan
    Ghisoni, Marco
    Selectively oxidized vertical-cavity surface-emitting lasers for high-speed data communication2001In: Proc. SPIE 4286, SPIE's Optoelectronics 2001, Photonics West, San Jose, US, Bellingham, WA, ETATS-UNIS: Society of Photo-Optical Instrumentation Engineers , 2001, Vol. 4286, 96- p.Conference paper (Refereed)
    Abstract [en]

    MITEL Semiconductor is developing the next generation low cost, high performance transceivers for data communication. The increasing quantity of data being transferred over the Internet demands very high capacity interconnects. A low cost, high-performance alternative is the use of parallel fiber interconnects where the light is, for example, coupled into a 12-channel fiber-ribbon. Parallel interconnects require good uniformity in order to reduce escalating costs and complexity. In this paper we report on the static and the modulation properties of 850nm multimode oxide VCSELs for use in such Gb/s transceiver system. Static power-current-voltage characteristics with good uniformity were obtained for different structures, with threshold currents down to sub-mA. A maximum small signal 3-dB bandwidth of 10 GHz and a modulation current efficiency up to 8.4 GHz/√[mA] were measured. Single channel results are presented for VCSELs operated at data rates from 2.5-10Gb/s.

  • 8. Ahlfeldt, H.
    et al.
    Holm, J.
    Lindgren, S.
    Backlin, L.
    Vieider, C.
    Klinga, T.
    Kerzar, B.
    Nilsson, M.
    Svensson, M.
    Nilsson, S.
    Kjebon, Olle
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    20 GHz bandwidth of lasers flip-chip-mounted on microstructured carriers with integrated electrical waveguides1998In: Optical Communication, 1998. 24th European Conference on, 1998, Vol. 1, 205-206 p.Conference paper (Refereed)
    Abstract [en]

    A flip-chip-mounting scheme for high-speed lasers has been realised. The mounting scheme involves a microstructured silicon carrier with integrated membrane transmission lines and self-aligning solder bumps

  • 9. Akram, N. M.
    et al.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Kjebon, Olle
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Experimental evaluation of carrier transport, gain, T0 and chirp of 1.55 mu;m MQW structures with different barrier compositions2005In: Optical Communication, 2005. ECOC 2005. 31st European Conference on, 2005, Vol. 2, 297-298 p.Conference paper (Refereed)
    Abstract [en]

    Direct carrier transport measurements were performed for different InGaAsP/InGaAlAs MQW test structures. Shallow InGaAlAs barrier QW showed faster carrier transport. Semi-insulating regrown FP lasers with InGaAlAs barrier QW showed improved high temperature operation, modal gain, differential modal gain and chirp.

  • 10.
    Akram, Nadeem
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Photonic devices with MQW active material and waveguide gratings: modelling and characterisation2005Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    The research work presented in this thesis deals with modelling, design and characterisation of passive and active optical waveguide devices. The rst part of the thesis is related to algorithm development and numerical modelling of planar optical waveguides and gratings using the Method of Lines (MoL). The basic three-point central-di erence approximation of the δ2=δx2 operator used in the Helmholtz equation is extended to a new ve-point and seven-point approximation with appropriate interface conditions for the TE and TM elds. Di erent structures such as a high-contrast waveguide and a TM surface plasmon mode waveguide are simulated, and improved numerical accuracy for calculating the optical mode and propagation constant is demonstrated. A new fast and stable non-paraxial bi-directional beam propagation method, called Cascading and Doubling algorithm, is derived to model deep gratings with many periods. This algorithm is applied to model a quasi-guided multi-layer anti-resonant reecting optical waveguide (ARROW) grating polarizing structure.

    In the second part of the thesis, our focus is on active optical devices such as vertical-cavity and edge-emitting lasers. With a view to improve the bandwidth of directly modulated laser, an InGaAsP quantum well with InGaAlAs barrier is studied due to its favorable band o set for hole injection as well as for electron con nement. Quantum wells with di erent barrier bandgap are grown and direct carrier transport measurements are done using time and wavelength resolved photoluminescence upconversion. Semi-insulating regrown Fabry-Perot lasers are manufactured and experimentally evaluated for light-current, optical gain, chirp and small-signal performance. It is shown that the lasers having MQW with shallow bandgap InGaAlAs barrier have improved carrier transport properties, better T0, higher di erential gain and lower chirp. For lateral current injection laser scheme, it is shown that a narrow mesa is important for gain uniformity across the active region. High speed directly modulated DBR lasers are evaluated for analog performance and a record high spurious free dynamic range of 103 dB Hz2=3 for frequencies in the range of 1-19 GHz is demonstrated. Large signal transmission experiment is performed at 40 Gb/s and error free transmission for back-to-back and through 1 km standard single mode ber is achieved.

  • 11.
    Akram, Nadeem
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Kjebon, Olle
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Chacinski, Marek
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Olsson, Fredrik
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Lourdudoss, Sebastian
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Berrier, Audrey
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    High-Speed Performance of 1.55 µm Buried Hetero-Structure Lasers with 20 InGaAsP/InGaAlAs Quantum-Wells2006In: 2006 European Conference on Optical Communications Proceedings, ECOC 2006, IEEE , 2006, 1-2 p.Conference paper (Refereed)
    Abstract [en]

    1550 nm re-grown FP lasers having 20 InGaAsP/InGaAlAs strain-balanced QWs exhibit low threshold current density, high T0 (78.0 #x000B0;C) and high resonance frequency (24 GHz) indicating that a large number of shallow barrier QWs are attractive for un-cooled high-speed direct-modulation applications.

  • 12.
    Akram, Nadeem
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Kjebon, Olle
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Marcinkevičius, Saulius
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Olsson, Fredrik
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Lourdudoss, Sebastian
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    The effect of barrier composition on the vertical carrier transport and lasing properties of 1.55-mu m multiple quantum-well structures2006In: IEEE Journal of Quantum Electronics, ISSN 0018-9197, E-ISSN 1558-1713, Vol. 42, no 7, 713-714 p.Article in journal (Refereed)
    Abstract [en]

    In this paper, the effect of barrier bandgap and composition on the optical performance of 1.55-mu m InGaAsP/In-GaAsP and InGaAsP/InGaAlAs multiple quantum-well structures and Fabry-Perot lasers is evaluated experimentally. Direct vertical carrier transport measurements were performed through strain-compensated multiple quantum-well (MQW) test structures using femto-second laser pulse excitation and time-resolved photoluminescence up-conversion method. MQW test structures were grown with different barrier composition (InGaAsP and InGaAlAs) and barrier bandgap (varied from lambda(g) = 1440 to 1260 nm) having different conduction band Delta E-c and valence band discontinuity Delta E-v, while keeping the same InGaAsP well composition for all the structures. The ambipolar carrier transport was found to be faster in the structures with lower valence band discontinuity Delta E-v. Regrown semi-insulating buried heterostructure Fabry-Perot (SIBH-FP) lasers were fabricated from similar QWs and their static light-current-voltage characteristics (including optical gain and chirp spectra below threshold) and thermal characteristics were measured. Lasers with InGaAlAs barrier showed improved high-temperature operation, higher optical gain, higher differential gain, and lower chirp, making them suitable candidates for high-bandwidth directly modulated uncooled laser applications.

  • 13.
    Akram, Nadeem
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Silfvenius, Christofer
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Material Physics (Closed 20120101), Semiconductor Materials, HMA (Closed 20120101).
    Kjebon, Olle
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Design optimization of InGaAsP-InGaAlAs 1.55 mu;m strain-compensated MQW lasers for direct modulation applications2004In: Indium Phosphide and Related Materials, 2004. 16th IPRM. 2004 International Conference on, IEEE , 2004, 418-421 p.Conference paper (Refereed)
    Abstract [en]

    A comprehensive simulation study of InGaAsP (well)/InGaAlAs(barrier) 1.55 mu;m strain-compensated MQW lasers is presented. For MQWs, a uniform vertical distribution of holes is achieved due to a reduced effective hole confinement energy by optimizing the bandgap and strain of the barriers and p-doping in the active region. Some preliminary results are also presented for the manufactured lasers using these QWs indicating a good material platform.

  • 14.
    Al Khatib, Iyad
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT. iITC, Sweden .
    Ismail, M.
    WNoC: A microelectronic system architecture suitable for biomedical wireless sensor networks2005Conference paper (Refereed)
    Abstract [en]

    This paper presents a low-cost microelectronic system architecture suitable for single chip CMOS integration. The system architecture consists of a large set of on-chip processing-cores, sensors, and four multi-standard wireless border cores that are interconnected to form an ultra-fast microelectronic network of distributed-computing systems. Our main application areas are: biomedical emergency monitoring systems and healthcare. The hardware platform is based on Network-on-Chip (NoC) design and RF circuitry for wireless connectivity. We focus on the design of this Wireless Network-on-Chip (WNoC). WNoC faces several challenges. A main issue of concern from the application point of view is to have the design support the convergence to a decision within acceptable periods of time, because time is critical in many medical healthcare applications. We define a mechanism to enable many WNoCs to interact together over the wireless media. A key result is a design and protocol for internal and external WNoC communications between the main and backup wireless cores. We run simulations on a biomedical monitoring system for emergency situations, and our results show that the time to converge to a medical warning is in the range of milliseconds, which is acceptable for the related medical scenarios.

  • 15.
    Al Khatib, Iyad
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Jantsch, Axel
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Nabiev, Rustam
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    ECG-BIONET: A global biomedical network for human heart monitoring and analysis: Performance needs of an electrocardiogram Telemedicine platform for medical aid at the point-of-need2006In: 25TH IEEE INTERNATIONAL CONFERENCE ON COMPUTER COMMUNICATIONS: VOLS 1-7, PROCEEDINGS IEEE INFOCOM 2006, New York: IEEE , 2006, 3282-3283 p.Conference paper (Refereed)
    Abstract [en]

    In this paper, we propose a Tele-medicine application platform as a medical aid for patients suffering from Heart malfunction. We focus on heart diseases since they remain by far the major cause of death in the globe. Our solution utilizes the Satellite communication protocol DVB-RCS (Digital Video Broadcast- Return Channel Satellite), Wi-Fi, and the Network-on-Chip (NoC) technology. We utilize the 12-lead ECG biomedical technique to detect heart disorders via the biomedical NoC, which transmits the medical alarm and results via the biomedical network, ECG-BIONET. We do not investigate the DVB-RCS standard or Wi-Fi technology, but rather we try to utilize this technology, and we look at it from a performance point of view for our application by investigating three parameters, namely: delay, packet loss, and reliability. We follow a top down approach by looking at the needs of the application from a performance guarantee for our specific-purpose network.

  • 16.
    Al Tayr, Hydar
    et al.
    KTH, School of Information and Communication Technology (ICT).
    Al Hakim, Mahmud
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Mobile Ajax2008Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report describes a master thesis performed at SICS (Swedish Institute of Computer Science) and KTH (The Royal Institute of Technology) in Stockholm.

    Ajax stands for "Asynchronous JavaScript and XML" and it's not a programming language, but a suite of technologies used to develop web applications with more interactivity than the traditional web pages.

    Ajax applications can be adapted for mobile and constrained devices. This has been called Mobile Ajax. While the technique is the same, Mobile Ajax generally is considered to be a special case of Ajax, because it deals with problems specific to the mobile market.

    The purpose of this thesis has been to examine which possibilities and disadvantages has the Mobile Ajax from developers and users perspective. In addition we compare Mobile Ajax with Java Micro Edition (Java ME) and Flash Lite.

    This has been done through literature studies and development of a databased chat client (MAIM -Mobile Ajax Instant Messenger). The application sends and receives direct messages in real time between differently mobile devices. Then MAIM application has been compared with our own developed Java ME and Flash Lite chat clients.

    We have tested all three applications with different models of mobile devices and on different web browsers. The results have shown that mobile Ajax makes possible the creation of sophisticated and dynamic mobile web applications and is better than the classic web application model, but this requires that the mobile device has a modern and compatible web browser like Opera mobile.

     

  • 17.
    Albrecht, Steffen
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Sigma-delta based techniques for future multi-standard wireless radios2005Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    Improvements in process technology and design innovations have resulted in compact and cost effective digital baseband solutions. The radio part, however, has remained a bottleneck in terms of chip area and power consumption as the feature size of analog devices does not directly benefit from scaling. With the addition of yet more standards into emerging products, the requirements of future radios will extend over characteristic performance features into demands of programmable and reconfigurable hardware for radios covering multiple frequency bands. Hence, a guideline in the design of such radios is a large degree of hardware sharing.

    The thesis investigates the application of sigma-delta modulation to arising multistandard wireless radios. First, it reviews principles in wireless radios, such as selected modulation and access techniques. It also examines several communication standards of personal wireless radios as well as common receiver architectures for their implementation. This is followed by general considerations and background information about sigma-delta modulators. In the third and fourth chapter, implementations to two blocks of a wireless radio receiver system are suggested: An architecture for a frequency synthesizer and an implementation of an analog-to-digital converter.

    In the first contribution, the thesis develops a novel concept for frequency synthesis that is more suitable for multi-band, multi-standard radio architectures, achieving a large amount of hardware sharing among different wireless standards. As a second pillar, the thesis contributes with the design of a dual-standard sigma-delta modulator for data conversion within a radio receiver. Parts of the work concerning the dual-standard modulator are embodied in a granted swedish patent.

  • 18.
    Alcala, Yvonne
    et al.
    New York Medical College .
    Olivecrona, Henrik
    Karolinska.
    Olivecrona, Lotta
    Karolinska.
    Noz, Marilyn E.
    New York University.
    Maguire Jr., Gerald Q.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Zeleznik, Michael P.
    Sollerman, Christer
    Sahlgrenska University Hospital, Göteborg, Sweden.
    Qualifying CT for wrist arthroplasty: Extending techniques for total hip arthroplasty to total wrist arthroplasty2005In: Medical Imaging 2005: Image Processing, Pt 1-3 / [ed] Fitzpatrick, JM; Reinhardt, JM, SPIE - The International Sooceity for Optical Engineeering , 2005, Vol. 5747, 1155-1164 p.Conference paper (Refereed)
    Abstract [en]

    The purpose of this study was to extend previous work to detect migration of total wrist arthroplasty non-invasively, and with greater accuracy. Two human cadaverous arms, each with a cemented total wrist implant, were used in this study. In one of the arms, I mm tantalum balls were implanted, six in the carpal bones and five in the radius. Five CT scans of each arm were acquired, changing the position of the arm each time to mimic different positions patients might take on repeated examinations. Registration of CT volume data sets was performed using an extensively validated, 3D semi-automatic volume fusion tool in which co-homologous point pairs (landmarks) are chosen on each volume to be registered. Three sets of ten cases each were obtained by placing landmarks on 1) bone only (using only arm one), 2) tantalum implants only, and 3) bone and tantalum implants (both using only arm two). The accuracy of the match was assessed visually in 2D and 3D, and numerically by calculating the distance difference between the actual position of the transformed landmarks and their ideal position (i.e., the reference landmark positions). All cases were matched visually within one width of cortical bone and numerically within one half CT voxel (0.32 mm, p = 0.05). This method matched only the bone/arm and not the prosthetic component per se, thus making it possible to detect prosthetic movement and wear. This method was clinically used for one patient with pain. Loosening of the carpal prosthetic component was accurately detected and this was confirmed at surgery.

  • 19.
    Al-Khatib, Iyad
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Poletti, Francesco
    Bertozzi, Davide
    Benini, Luca
    Bechara, Mohamed
    Khalifeh, Hasan
    Jantsch, Axel
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Nabiev, Rustam
    A Multiprocessor System-on-Chip for Real-Time Biomedical Monitoring and Analysis: Architectural Design Space Exploration2006In: DAC '06: Proceedings of the 43rd annual Design Automation Conference, 2006, 125-130 p.Conference paper (Refereed)
    Abstract [en]

    In this paper we focus on MPSoC architectures for human heart ECGreal-time monitoring and analysis. This is a very relevant bio-medicalapplication, with a huge potential market, hence it is an ideal targetfor an application-specific SoC implementation. We investigate asymmetric multi-processor architecture based on STMicroelectronicsVLIW DSPs that process in real-time 12-lead ECG signals. Thisarchitecture improves upon state-of-the-art SoC designs for ECGanalysis in its ability to analyze the full 12 leads in real-time, evenwith high sampling frequencies, and ability to detect heartmalfunction. We explore the design space by considering a number ofhardware and software architectural options.

  • 20.
    Almkvist, Magnus
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Wahren, Marcus
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Preserving Integrity inTelecommunication Networks Opened bythe Parlay Service Interface2002Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This Master’s Thesis in Electrical Engineering concerns the introduction of a Parlay gateway in Skanova’s public circuit switched telephone network, what network integrity problems this brings, and how to preserve the integrity of the network.

    There is a rising demand from the market on Skanova to be able to offer integrated and useful services via their network. Examples of such services are Web Controlled Call Forwarding and Virtual Call Centres. Until now, these services have been implemented with the Intelligent Network concept which is a technology for concentrating the service logic in the telephone network to centralised service platforms within the network operator’s domain. Developing new services in this environment is expensive and therefore, Skanova wants to open the network for third party service providers. The opening of the network is enabled by the introduction of a gateway implementing the open service interface Parlay.

    The crucial point when opening the network for third party service providers is to maintain the integrity of the network. Parlay is an object oriented Application Programming Interface that enables a third party service access to core network resources in a controlled manner.

    The authors’ definition of network integrity is: “the ability of a network to steadily remain in a safe state, while performing according to the expectations and specifications of its owner, i.e. delivering the expected functionality and providing means to charge for utilised network resources”.

    The thesis describes a few services implemented via the Parlay interface and points out examples of activities in these services that may jeopardise the integrity of the network. The described activities belong to one of the two categories: Call Control Functionality or Lack of Charging Instruments.

    The thesis also describes two important methods for addressing encountered integrity problems. The methods are: Parlay Service Level Agreement and Policy Management.</p> Finally, the solutions are compared and the conclusion is that Policy Management is a conformable and flexible method for addressing lots of integrity problems and that these are important qualities, since new integrity problems will arise all the time.

  • 21.
    Altinkaya, Martin
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Ahmedi, Saman
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    SIP in an Interconnector and Service Provider Role2001Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This Master’s Thesis concerns the technical problems and solutions in the Telia Mobile’s Golden Gate Architecture. The Golden Gate project will bridge service control from the IPnetwork to the circuit switched network. Connecting the different users of PSTN, GSM, W-LAN, and GPRS networks together will require solutions to many problems. Most of the problems have already been defined by Telia. Our task is to evaluate two parts of the Golden Gate architecture, namely the Interconnect- and Service Provider roles.

    The Interconnector provider connects networks of different technical standards and enables other network operators to reach Service Providers on the Internet or other IP-based networks. The role concerns mainly mapping between SS7 signaling and the Session Initiation Protocol (SIP), charging and billing. Via the Interconnector the Service Provider can connect different services to any network.

    We will describe the SIP-protocol in detail and then we will look into the mapping between SS7 and SIP. We will also propose a charging model. It is important to have a solution that supports roaming between the different networks, we will evaluate such a solution. Most of the protocols (INAP, ENUM, MAP and ISUP) that are involved in the Golden Gate architecture are not completely defined. There are many Internet Drafts that discuss the possible functionality of the protocols and the interworking between them. Many different Internet-workgroups are working with these issues. No one seems to have the right answers for the interconnection between the protocols involved.

    Since the IP-telephony will probably replace today’s telephony systems, it is important to ensure a suitable Quality of Service (QoS), security that guarantees privacy, and a fair billing function. These are the three major problems in the IP-telephony world. IP-Telephony or Voice over IP (VoIP) has been on the market for a long time, there are many 'free IP-call sites' that use VoIP, but the quality of the calls are not yet good enough to replace traditional telephony. Our task here is to make sure that the necessary quality of service is provided, and a reliable charging model is used.

  • 22.
    Amin, Yasar
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Tenhunen, Hannu
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Jamal, Habibullah
    Zheng, Li-Rong
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Duo, Xinzhong
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Chip-package codesign of receiver front end modules for RF/wireless applications2005In: 2005 IEEE/ACES International Conference on Wireless Communications and Applied Computational Electromagnetics, New York: IEEE , 2005, 767-770 p.Conference paper (Refereed)
  • 23.
    Amin, Yasar
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT. Computer Engineering Department, University of Engineering and Technology Taxila, Pakistan .
    Tenhunen, Hannu
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Zheng, Lirong
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Duo, Xinzhong
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    SoP design on liquid crystal polymer substrate for 5 GHz RF receiver front-end module2005In: International Microelectronics and Packaging Society - 1st International Conference and Exhibition on Device Packaging 2005: Everything in Electronics Between the Chip and the System, 2005, 236-240 p.Conference paper (Refereed)
    Abstract [en]

    Next generation wireless communications terminals will demand the use of advanced component integration processes and high density packaging technologies in order to reduce size and to increase performance. This paper presents highdensity multilayer interconnects and integrated passives used to design high performance prototype filter for 5GHz wireless LAN receiver realized on liquid crystal polymer (LCP) substrate. The thin film implementation of Multichip Module technology is identified as a useful platform for the integration of GaAs MMIC and silicon device technologies for microwave applications where performance, size and weight are critical factors. The ability of the MCM-D technology to provide controlled impedance, microstrip structures and integrated thin film passive components with useful performance in the microwave frequency regime has now been demonstrated.

  • 24.
    Andersson, Ulf
    et al.
    KTH, School of Computer Science and Communication (CSC), Centres, Centre for High Performance Computing, PDC. KTH, School of Computer Science and Communication (CSC).
    Qiu, Min
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Zhang, Ziyang
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Parallel Power Computation for Photonic Crystal Devices2006In: Methods and Applications of Analysis, ISSN 1073-2772, E-ISSN 1945-0001, Vol. 13, no 2, 149-156 p.Article in journal (Refereed)
    Abstract [en]

    Three-dimensional finite-different time-domain (3D FDTD) simulation of photonic crystal devices often demands large amount of computational resources. In many cases it is unlikely to carry out the task on a serial computer. We have therefore parallelized a 3D FDTD code using MPI. Initially we used a one-dimensional topology so that the computational domain was divided into slices perpendicular to the direction of the power flow. Even though the speed-up of this implementation left considerable room for improvement, we were nevertheless able to solve largescale and long-running problems. Two such cases were studied: the power transmission in a two-dimensional photonic crystal waveguide in a multilayered structure, and the power coupling from a wire waveguide to a photonic crystal slab. In the first case, a power dip due to TE/TM modes conversion is observed and in the second case, the structure is optimized to improve the coupling. We have also recently completed a full three-dimensional topology parallelization of the FDTD code.

  • 25.
    Andreasson, Carin
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Usability Studies of Wireless LAN Systems: *Design of the MUST – Method for Usability Studies and Tests*2001Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This document presents the thesis project “Usability Studies of Wireless Systems, Design of the MUST – Method for Usability Studies and Tests” that was part of the requirements for the degree of Master of Science in Electrical Engineering at the Royal Institute of Technology. The work was carried out at Ericsson WLAN Systems. They develop mobile enablers and had realized the importance of adding input, from the actual users of the systems, into the developing process. The problem was that Ericsson WLAN Systems did not have any kind of strategy for performing usability studies or user tests. The need for a method for usability studies initiated this thesis project.

    The method is called MUST (Method for Usability Studies and Tests) and directs itself towards a project leader and/or usability engineer. It interprets the indistinct and abstract declarations of usability into concrete tools for usability engineering. The method is applied alongside the ordinary development process to enable early and constant focus on usability and to structure the usability engineering. The MUST is divided into five different phases that form a lifecycle, describing the workflow when conducting usability engineering: Know the User, Setting Goals, Prototyping, Testing and User Feedback. Every phase within the MUST lifecycle has a specified goal to be achieved and methods to be used to achieve it. MUST also helps connecting the information flow from product management through software design to support.

    MUST has been tested in parts within this thesis project. Ericsson’s High Security System was put through a Thinking Aloud Test and new and interesting data was gathered through this test, revealing what the users really thought about the product as well as how they actually interacted with it. The results became valuable input to the up-grades of the High Security System.

  • 26.
    Angulo Barrios, C.
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Lourdudoss, Sebastian
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT. KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Messmer, L. R.
    Holmgren, M.
    Lovqvist, A.
    Carlsson, C.
    Larsson, A.
    Halonen, J.
    Ghisoni, M.
    Stevens, Renaud
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    GaAs/AlGaAs buried-heterostructure laser diodes with semi-insulating GaInP:Fe regrowth2001In: Lasers and Electro-Optics, 2001. CLEO/Pacific Rim 2001. The 4th Pacific Rim Conference on, 2001, Vol. 2Conference paper (Refereed)
    Abstract [en]

    GaAs/AlGaAs buried-heterostructure in-plane lasers and vertical-cavity surface-emitting lasers using GaInP:Fe as the burying layer have been fabricated and investigated. Regrowth of GaInP:Fe around etched laser mesas was achieved by hydride vapor phase epitaxy. The lasers exhibit good performance under CW operation and show promising high-speed characteristics.

  • 27. Ao, Xianyu
    et al.
    Liu, Liu
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Wosinski, Lech
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    He, Sailing
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Polarization beam splitter based on a two-dimensional photonic crystal of pillar type2006In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Applied physics letters, Vol. 89, no 17, 171115- p.Article in journal (Refereed)
    Abstract [en]

    Negatively and positively refractive behaviors are achieved in a two-dimensional photonic crystal of pillar type for TE and TM polarizations, respectively, at the same frequency. The photonic crystal is formed by a triangular lattice of silicon pillars of finite height on a silicon substrate. A polarization beam splitter based on such a photonic-crystal slab is demonstrated. Measurements at near infrared wavelengths indicate that two beams of different polarizations can be split with an extinction ratio of over 10 dB in a wide wavelength range.

  • 28. Arulkumaran, S.
    et al.
    Ng, G. I.
    Tan, C. L.
    Liu, Z. H.
    Bu, J.
    Radhakrishnan, K.
    Aggerstam, T.
    Sjodin, M.
    Lourdudoss, Sebastian
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Enhancement of both direct-current and microwave characteristics of AlGaN/GaN high-electron-mobility transistors by furnace annealing2006In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 88, no 2Article in journal (Refereed)
    Abstract [en]

    The enhancement of both direct-current (dc) and microwave characteristics of AlGaN/GaN high-electron-mobility transistors (HEMTs) were demonstrated by conventional furnace annealing at 400 degrees C for 5 min. Due to the improvement in Ni/Au Schottky contact properties by furnace annealing, about 17%, 34%, 23%, and 25% of enhancements in maximum drain current density, maximum extrinsic transconductance (g(m max)), cutoff frequency and maximum oscillation frequency were observed, respectively. A positive threshold voltage shift and the increase in g(m max) can also be correlated to the improved Schottky parameters such as ideality factor and barrier height. The annealed devices exhibited low reverse gate-leakage-current by more than three orders of magnitude and low drain-leakage-current by two orders of magnitude. Correspondingly, the devices exhibited 55% of higher breakdown voltage after annealing. The furnace annealing is an effective and viable means to enhance both dc and microwave characteristics of AlGaN/GaN HEMTs.

  • 29.
    Atallah, Jad G.
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Michielsen, Wim
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Elnaggar, Mohammed Ismail
    Firstpass Semiconductors AB.
    A frequency planning and generation scheme for multi-standard wireless transceivers2005In: 12th IEEE International Conference on Electronics, Circuits and Systems, ICECS 2005: Gammarth, 11 December 2005 through 14 December 2005, 2005Conference paper (Refereed)
    Abstract [en]

    This work presents a novel frequency planning scheme associated with a reference frequency generation scheme that has the potential of providing low phase noise contribution for several wireless standards including DCS1800, WCDMA II and III, DECT, WLAN a/b/g and Bluetooth. The scheme is particularly useful when implemented in future technologies and can be extended to cover newer wireless standards in newer bands of interest. It uses a single multi-band voltage-controlled oscillator (VCO) with switching inductors and high speed dividers directly generating the quadrature outputs. The VCO itself covers the frequency ranges from 4.8GHz to 6GHz and from 6.8GHz to 8GHz. Its phase noise is -136dBc/Hz at 1MHz offset from a center frequency of 1.85GHz. The design is sent for fabrication using 0.18ÎŒm CMOS.

  • 30. Aubin, G.
    et al.
    Talneau, A.
    Uddhammar, Anna
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Berrier, Audrey
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Mulot, Mikael
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Highly dispersive photonic crystal-based guiding structures2006In: CLEO/QELS 2006, Optical Society of America, 2006, 972-974 p.Conference paper (Refereed)
    Abstract [en]

    Propagating modes supported by Photonic-Crystal guiding structures can demonstrate very high group velocity dispersion close to a cut-off. We investigate here the wavelength dependence of the dispersion for different Photonic Crystal structures.

  • 31.
    Avgeropoulos, Konstantinos
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Service Policy Management for User-Centric Services in Heterogeneous Mobile Networks,2004Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Session Initiation Protocol (SIP) is a signaling protocol for IP-based media services that will be the de facto standard for future media-over-IP services. Since SIP User Agents (UAs) support a limited number of service types (usually one or two), we assume that the future user will need to operate several UAs simultaneously. These UAs will constitute the user's personal service network. In this thesis, we investigate architectures for policy-based management of this network so that it can be used in an efficient manner. To achieve this, we propose a new SIP entity, called the SIP Service Manager (SSM), which lies in the core of the management system. Finally, we evaluate our proposal by implementing one version of the SIP Service Manager.

  • 32.
    Ayguadé, Eduard
    et al.
    European Center for Parallelism of Barcelona (CEPBA), Technical University of Catalunya (UPC).
    Brorsson, Mats
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Brunst, H.
    ) Center for High Performance Computing (ZHR), TU Dresden.
    Hoppe, H. -C
    Pallas GmbH.
    Karlsson, S.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Martorell, X.
    European Center for Parallelism of Barcelona (CEPBA), Technical University of Catalunya (UPC).
    Nagel, W. E.
    ) Center for High Performance Computing (ZHR), TU Dresden.
    Schlimbach, F.
    Pallas GmbH.
    Utrera, G.
    European Center for Parallelism of Barcelona (CEPBA), Technical University of Catalunya (UPC).
    Winkler, M.
    ) Center for High Performance Computing (ZHR), TU Dresden.
    OpenMP Performance Analysis in the INTONE Project2001Conference paper (Refereed)
  • 33.
    Ayrault, Cécile
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Service discovery for Personal Area Networks2004Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the increasing use of electronic devices, the need for affordable wireless services specifically context-aware services, in a so-called Personal Area Network (PAN) is becoming an area with significant potential. Service discovery is a basic function.

    Even though a number of service discovery protocols have been implemented, a specific protocol for a PAN environment may need to be developed, as the characteristics of a PANs differ from other networking environments. Thus, the specific requirements for service discovery from a PAN perspective were studied. Methods for service discovery will be described that take into account both local and remote services.

    These methods will then be evaluated in a SIP telephony infrastructure to decide where a call should be delivered. The location of a person is done by using the implemented service discovery.

  • 34.
    Backlund, Ola
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Policy-based IP services over UMTS2001Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Providing services over IP with real-time characteristics are one of the challenges that the next generation UMTS operators arefacing. Offering these services with adequate quality will be an important task in the management of their networks, which to alarge extent will be built on IP technology. Policy-based network management is an approach to improving network performanceand QoS. This is a network management model, suitable for highlevel service management that has been proposed as a promisingsolution for dynamic QoS. It is well suited for networks with hierarchical service models, which is the situation encountered inUMTS.

    The aim of this Master thesis is to examine IP services providedover UMTS based on the ideas from policy-based network technology and how they can be applied to this next generation ofcellular systems. A framework for policy-based QoS management support is outlined for the packet domain of UMTS, which is basedon the principles and experience derived from policy-based network technology found in fixed networks. A description of thefunctions and capabilities of a policy-based management system designed for UMTS is given, and the QoS related problems inUMTS are identified in order to evaluate the bottlenecks for improving service quality. The report ends with a proposal to howTelia may provide UMTS access to a IP access node that is currently being tested and developed in co-operation with othermanufacturers. Two possible solutions are described and evaluated from a QoS and architectural perspective.

  • 35.
    Badel, Xavier
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Electrochemically etched pore arrays in silicon for X-ray imaging detectors2005Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Digital devices have now been introduced in many X-ray imaging applications, replacing slowly traditional photographic films. These devices are preferred as they offer real time imaging, easy handling and fast treatment of the images. However, the performance of the detectors still have to be improved in order to increase the image quality, and possibly reduce the X-ray dose, a vital parameter for medical use. In this thesis, three different new detector concepts have been investigated. All designs use pore arrays, which are ideal starting structures to form pixellated detectors.

    Electrochemical etching of n-type silicon in aqueous hydrofluoric acid solution (HF) has been studied to form these pore arrays. A broad range of pores have been fabricated with diameters varying from 200 nm to 40 µm and with depths reaching almost the wafer thickness, thus leading to very high aspect ratios. The technique was also found to be suitable for the formation of other types of structures such as pillars and tubes on the sub micrometer scale. The etching is based on the dissolution of silicon in HF under anodic bias and a supply of positive electrical carriers (holes). As holes are the minority carriers in n-type silicon, they are usually photo-generated. In this work an alternative technique, based on hole injection from a forward-biased pn junction, has been successfully pioneered.

    The first X-ray imaging detector concept presented in the thesis consists of a silicon charge coupled device (CCD) in proximity with a scintillating screen. The screen is made from a pore array having reflective pore walls and filled with CsI(Tl), emitting photons at a wavelength of 550 nm under X-ray exposure. The secondary emitted photons are light-guided by the pore walls and then detected by the CCD pixels. Detectors were fully fabricated and characterized. This concept provides good spatial resolution with negligible cross talk between adjacent pixels. The dependences of the detector efficiency on pore depth and on the coating of the pore walls are presented. Although most of the produced detectors had a detective quantum efficiency of about 25%, some detectors indicate that efficient scintillating screens can be achieved approaching the theoretical limit as set by poissonian statistics of the X-ray photons.

    The two other detector designs require the formation of vertical pn junctions, i.e. in the pore walls. In one concept the secondary emitted photons are detected by photodiodes located in the pore walls. This would lead to high charge collection efficiency as the photons do not have to be guided to one end of the pore. However, high noise due to the direct detection of X-rays in the diodes is expected. The other concept is based on generation of electron-hole pairs in a semiconductor and the ‘3D’ detector, where an array of vertical electrodes is used to separate the charges via an electric field. To uniformly dope the inside of deep pores, both boron diffusion and low-pressure chemical vapor diffusion of boron-doped poly-silicon were shown to be successful techniques. This was confirmed by SIMS profiles taken through the pore wall thickness. Finally, the possibility to form individual junction in each pore was shown. The diodes were electrically characterized, demonstrating good rectifying behavior and sensitivity to light.

  • 36.
    Badel, Xavier
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Domeij, Martin
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Linnros, Jan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Doping of electrochemically etched pore arrays in n-type silicon: processing and electrical characterization2005In: Journal of the Electrochemical Society, ISSN 0013-4651, Vol. 152, no 4, G252-G258 p.Article in journal (Refereed)
    Abstract [en]

    Silicon p-n diodes formed in the walls of deep pores have been electrically characterized. The pores were electrochemically etched in low-doped n-type silicon substrates, and the entire pore array was doped p(+) by boron diffusion at 1050 degrees C. Two different process flows were investigated to disconnect the p(+) layers from one pore to another. The first consists of removing a few micrometers of silicon at the top of the sample using reactive ion etching after diffusion while the second enables the prevention of doping at the top of the pore walls with an oxide, acting as a barrier during diffusion. Current-voltage and capacitance-voltage characteristics of p-n junctions are presented and related parameters, such as the serial resistance and the ideality factor are discussed. The results show good rectifying behavior of the diodes with a reverse current about four to five decades smaller than the forward current. Measurements with two pores connected in a transistor-like configuration (p(+)/n(-)/p(+)), were also performed. Device simulations were used to examine the device behavior. Finally, our results demonstrate that pores could work as individual detector pixels for moderate reverse voltages, suitable for radiation imaging applications.

  • 37.
    Badel, Xavier
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Norlin, B.
    Department of Information Technology and Media, Mid-Sweden University, Sundsvall.
    Kleimann, P.
    LENAC, Université Claude Bernard Lyon-I, Villeurbanne.
    Williams, L.
    Applied Scintillation Technology, Harlow.
    Moody, S. J.
    Applied Scintillation Technology, Harlow.
    Tyrell, G. C.
    Applied Scintillation Technology, Harlow.
    Fröjdh, C.
    Department of Information Technology and Media, Mid-Sweden University, Sundsvall.
    Linnros, Jan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Performance of scintillating waveguides for CCD-based X-ray detectors2006In: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 53, no 1, 3-8 p.Article in journal (Refereed)
    Abstract [en]

    Scintillating films are usually used to improve the sensitivity of CCD-based X-ray imaging detectors. For an optimal spatial resolution and detection efficiency, a tradeoff has to be made on the film thickness. However, these scintillating layers can also be structured to provide a pixellated screen. In this paper, the study of CsI(TI)-filled pore arrays is reported. The pores are first etched in silicon, then oxidized and finally filled with CsI(TI) to form scintillating waveguides. The dependence of the detector sensitivity on pore depth, varied from 40 to 400 mu m here, follows rather well theoretical predictions. Most of the detectors produced in this work have a detective quantum efficiency of the incoming X-ray photons of about 25%. However, one detector shows that higher efficiency can be achieved approaching almost the theoretical limit set by Poisson statistics of the incoming X-rays. Thus, we conclude that it is possible to fabricate scintillating waveguides with almost ideal performance. Imaging capabilities of the detectors are demonstrated.

  • 38.
    Bagula, Antoine B
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Hybrid IGP+MPLS routing in next generation IP networks: an online traffic engineering model2005In: QUALITY OF SERVICE IN MULTISERVICE IP NETWORKS, PROCEEDINGS / [ed] Marsan MA; Bianchi G; Listanti M; Meo M, 2005, Vol. 3375, 325-338 p.Conference paper (Refereed)
    Abstract [en]

    Hybrid routing approaches which either combine the best of traditional IGP and MPLS routing or allow a smooth migration from traditional IGP routing to the newly proposed MPLS standard have scarcely been addressed by the IP community. This paper presents an on-line traffic engineering (TE) model which uses a hybrid routing approach to achieve efficient routing of flows in IP networks. The model assumes a network-design process where the IP flows are classified at the ingress of the network and handled differently into the core using a multiple metric routing mechanism leading to the logical separation of a physical network into two virtual networks: An IGP network carrying low bandwidth demanding (LBD) flows and an MPLS network where bandwidth-guaranteed tunnels are setup to route high bandwidth demanding (HBD) flows. The hybrid routing approach uses a route optimization model where (1) link weight optimization (LWO) is implemented in the IGP network to move the IP flows away from links that provide a high probability to become bottleneck for traffic engineering and (2) the MPLS network is engineered to minimize the interference among competing flows and route the traffic away from heavily loaded links. We show that a cost-based optimization framework can be used by an ISP to design simple and flexible routing approaches where different metrics reflecting the ISP ' s view of its TE objectives are deployed to improve the use and efficiency of a network. This is achieved through extensions to a mixed cost metric derived from the route optimization model. The IGP+MPLS routing approach is applied to compute paths for the traffic offered to a 15- and 50-node network. Preliminary simulation reveals performance improvements compared to both IGP and MPLS routing in terms of the routing optimality and the network reliability.

  • 39.
    Bagula, Antoine B
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Hybrid routing in next generation IP networks2006In: Computer Communications, ISSN 0140-3664, E-ISSN 1873-703X, Vol. 29, no 7, 879-892 p.Article in journal (Refereed)
    Abstract [en]

    This paper presents a hybrid approach for routing flows in IP networks to achieve an optimal network configuration maximising bandwidth usage (optimality), minimising re-routing upon failure (reliability) and reducing the signalling overheads resulting from a full IP tunnelling (scalability). We formulate the routing of flows in IP networks as a service differentiated model where the IP flows are classified into high bandwidth demanding (LBD) and low bandwidth demanding (LBD) flows at the ingress of the network and handled differently into the core using a hybrid IGP+MPLS approach where the LBD flows are routed over the existing IGP paths while the HBD flows are carried over MPLS bandwidth-guaranteed tunnels. This model can be deployed in heterogenous network environments where HBD flows carrying real-time traffic and LBD flows transporting best-effort traffic are handled differently over a common transport network implementing traffic prioritization in response to natural or man-made emergencies. We consider the routing of flows within an IP domain's boundaries and evaluate the efficiency of the new routing approach under uniform and bursty traffic profiles. We apply the routing approach to compute paths for the traffic offered to a 20- and 50-node test networks. Simulation reveals that the hybrid routing approach outperforms both IGP and MPLS routing under the network conditions and test network models considered.

  • 40.
    Bagula, Antoine B
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    On achieving bandwidth aware LSP/λSP multiplexing separation in multi-layer networks2007In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008Article in journal (Other academic)
  • 41.
    Bagula, Antoine B
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Traffic engineering next generation IP networks using gene expression programming2006In: Proceedings of the 2006 IEEE, 2006, 230-239 p.Conference paper (Refereed)
    Abstract [en]

    This paper addresses the problem of Traffic Engineering (TE) to evaluate the performance of evolutionary algorithms when used as IP routing optimizers and assess the relevance of using "Gene Expression Programming (GEP)" as a new fine-tuning algorithm In destination- and How-based TE. We consider a TE scheme where link weights are computed using GEP and used as either fine-tuning parameters in Open Shortest Path First (OSPF) routing or static routing cost In Constraint Based Routing (CBR). The resulting OSPF and CBR, algorithms are referred to as OSPFgep and CBRgep. The GEP algorithm is based on a hybrid optimisation model where local search complements the global search implemented by classical evolutionary algorithms to improve the genetic individuals fitness through hill-climbing. We apply the newly proposed TE scheme to compute the routing paths for the traffic offered to a 23-, 28- and 30-node test networks under different traffic conditions and differentiated services situations. We evaluate the performance achieved by the OSPFgep, CBRgep algorithms and OSPFma,destination-based routing algorithm where OSPF path selection Is driven by the link weights computed by a Memetic Algorithm (MA). We compare the performance achieved by the OSPFgep algorithm to the performance of the OSPFma and OSPF algorithms in a simulated routing environment using NS. We also compare the quality of the paths found by the CBRgep algorithm to the quality of the paths computed by the Constraint Shortest Path First (CSPF) algorithm when routing bandwidth-guaranteed tunnels using connection-level simulation. Preliminary results reveal the relative efficiency of (1) the OSPFgep algorithm compared to both the OSPFma and OSPF algorithms and (2) the CBRgep algorithm compared to CSPF routing.

  • 42.
    Bagula, Antoine B
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Krzesinski, A. E.
    Traffic and network engineering in emerging generation IP networks: a bandwidth on demand model2006In: Proceedings of the 1st IEEE International Workshop on Bandwidth on Demand / [ed] Hausheer D; Rabbat R; Hamada T; Stiller B; Walrand J, 2006, 36-43 p.Conference paper (Refereed)
    Abstract [en]

    This paper assesses the performance of a network management scheme where network engineering (NE) is used to complement traffic engineering (TE) in a multi-layer setting where a data network is layered above an optical network. We present a TE strategy which is based on a multi-constraint optimization model consisting of finding bandwidth-guaranteed IP tunnels subject to contention avoidance minimization and bandwidth usage maximization constraints. The TE model is complemented by a NE model which uses a bandwidth trading mechanism to rapidly re-size and re-optimize the established tunnels (LSPs/lambda SPs) under Quality of Service (QoS) mismatches between the traffic carried by the tunnels and the resources available for carrying the traffic. The resulting TE+NE strategy can be used to achieve bandwidth on demand (BoD) in emerging generation IP networks using a (G)MPLS-like integrated architecture in a cost effective way. We evaluate the performance of this hybrid strategy when routing, re-routing and re-sizing the tunnels carrying the traffic offered to a 23-node test network.

  • 43.
    Balkorkian, Sevag
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Hao, Zhang
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Analysis of Internal RF Interferences in Mobile2005Independent thesis Basic level (professional degree), 20 points / 30 hpStudent thesis
    Abstract [en]

    Nowadays, mobile phones have greater functionality; a camera, color LCD screen, wireless LAN, Bluetooth, IrDA and others. In the near future wider variety of new functionalities will be added, from high quality voice, high definition video to high data rate wireless channels. As consumer electronics integrate greater functionality and high operating frequencies, their emissions will exceed the specified limits, most of these emissions will be a result of the internal interferences in the mobile phone. Moreover higher operating frequencies will be required to improve the quality of these functionalities, something that will make it more difficult to control these interferences. Internal or external sources of electromagnetic interference can degrade the performance of sensitive analog/digital circuits inside the mobile phone. Moreover the electronic device must satisfy a host of global regulations that limit it’s susceptibility to these interferences, as well as the interference emitted by the device itself.

    Therefore designing a new electronic device to perform new and exciting functions will not be a pleasant task if it can not meet certain specifications and function as required to adhere to certain global regulations.

    This thesis project investigates the sources of interference inside a mobile phone; mainly the electromagnetic interferences and its effect on the radio transceiver focusing on the GSM receiver sensitivity. This report is a result of intensive research, an investigation of possible sources of interference, also actual measurements were performed; RSSI, OTA and sniffing measurements; to identify the physical sources of interferences, and their effect on the receiver sensitivity. Finally solutions were recommended and implemented to suppress the interferences due to different sources, mainly through filtering, shielding or proper grounding of signals and components/subsystems in the mobile phone.

  • 44. Bandelow, U.
    et al.
    Schatz, Richard
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP. KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Wunsche, H. -J
    A correct single-mode photon rate equation for multisection lasers1996In: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 8, 614-616 p.Article in journal (Refereed)
    Abstract [en]

    It is shown that not the photon number but photon number divided by the square root of the excess factor of spontaneous emission must be used in the photon rate equation for single-mode lasers when the longitudinal field distribution changes with time. The importance of using the correct dynamic quantity is illustrated with two examples.

  • 45. Battiti, R.
    et al.
    Lo Cigno, R.
    Sabel, M.
    Orava, Fredrik
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT. KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Pehrson, Björn
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT. KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Wireless LANs: From WarChalking to open access networks2005In: Journal on spesial topics in mobile networks and applications, ISSN 1383-469X, E-ISSN 1572-8153, Vol. 10, no 3, 275-287 p.Article in journal (Refereed)
    Abstract [en]

    This work discusses the evolution of W-LANs from their current status of wireless termination of LAN services to a possible global infrastructure where the access networks become open to multiple operators and a vehicle of a win-win scenario, where both users and operators benefit from the new network architecture. The idea of Open Access Networks (OANs) can go beyond wireless HotSpots and be generalized to a generic shared access infrastructure that fosters service operators competition and drastically reduces the cost of last mile coverage. The general concept of Open Access Networks is detailed, highlighting its difference with the more traditional model of vertical integration of the access network into the global service. About the OANs development, it is shown how to support the quick and smooth evolution of the infrastructure toward a widespread and reliable communication support. Business models are discussed by mentioning the different actors, the market organization and the different organization forms. The final part of the paper is devoted to technical challenges such as access control, security, privacy, roaming, resource exploitation and service differentiation. As an example of how to tackle these problems, we discuss a pricing technique devoted to resource management and billing support. In addition we present a simulation on how the OAN concept can speed-up the deployment of broadband access in a real case.

  • 46. Bennett, N. S.
    et al.
    Radamson, Henry H.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Beer, C. S.
    Smith, A. J.
    Gwilliam, R. M.
    Cowern, N. E. B.
    Sealy, B. J.
    Enhanced n-type dopant solubility in tensile-strained Si2008In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 517, no 1, 331-333 p.Article in journal (Refereed)
    Abstract [en]

    The creation of highly conductive ultrashallow-doped regions in strained Si is a key requirement for future Si based devices. It is shown that in the presence of tensile strain, Sb becomes a contender to replace As in strain-engineered CMOS devices due to advantages in sheet resistance. While strain reduces resistance for both As and Sb; a result of enhanced electron mobility, the reduction is significantly larger for Sb due to an increase in donor activation. Differential Hall measurements suggest this is a consequence of a strain-induced Sb solubility enhancement following solid-phase epitaxial regrowth, increasing Sb solubility in Si to levels approaching 10(21) cm(-3). Experiments highlight the importance of maintaining substrate strain during thermal annealing to maintain this high Sb activation.

  • 47. Benyattou, T.
    et al.
    Martin, M.
    Orobtchouk, R.
    Talneau, A.
    Berrier, Audrey
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Mulot, Mikael
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Anand, Srinivasan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Optical Bloch waves studied by near optical field microscopy2005In: Journal of the Korean Physical Society, ISSN 0374-4884, Vol. 47, S72-S75 p.Article in journal (Refereed)
    Abstract [en]

    Photonic bandgap structures are very promising for the integration of optical function at the nanoscale level and particularly 2D structures perforated on a slab waveguide. In this context, photonic crystal waveguides obtained by removing rows of holes in the periodic structure are very interesting. We will present here, results of near field optical microscopy conducted on PCW. With a Fourier transform analysis of the image, we can image the Bloch waves propagating in the waveguide. The results are compared to FDTD simulations and we will show that the images obtained correspond to the electric field. Such result allows us to study the interaction of the optical tip with the electromagnetic field. 2D FDTD simulations of 1D photonic crystal interaction with a SNOM tip is presented. The results obtained confirm that the SNOM signal is mainly related to the electric field.

  • 48.
    Berggren, Anders
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Borg, Martin
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    A Comparative Study ofTwo Multicast Routing Algorithms2002Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This Master Thesis examines several aspects of two different multicast forwarding algorithms. The scaling properties of the currently used algorithms were examined under different criteria, such as delay, traffic concentration, and size of the routing tables.

    Many new Internet applications, such as videoconferencing, resource discovery, Internet radio and online games, depend on a network support for efficient point-to-multipoint communication. Sending identical data to a group of receivers using a series of unicast transmissions obviously has massive scaling problems. Multicasting provides an efficient and elegant solution that significantly reduces the total bandwidth demand as well as the load on both senders and intermediate routers.

    In this report we study two multicast routing algorithms, source based trees (SBT) and core based trees (CBT). SBT builds one delivery tree per source and group by flooding the initial packet through the entire network, and then removing the links that do not lead to group members (“pruning”). To be able to discover new members, flooding must occur periodically. CBT on the other hand, builds one delivery tree per group, shared by all sources. There is one core router per group and members must explicitly join the delivery tree by notifying the core. Off-tree sources must tunnel their traffic to the core for distribution along the tree.

    SBT has two main drawbacks. Firstly, the maintenance of the delivery tree requires periodic flooding of the network. Furthermore, SBT routers must keep state that grows as the product of the number of sources and the number of groups. CBT solves both of these scaling problems, but the shared tree will often lead to sub-optimal paths and increased delay. The traffic may also be concentrated on fewer links than in SBT.

    We compared the characteristics of the SBT and CBT algorithms in different network topologies using a simulation program. Since existing network simulation tools were found to be poor when it came to multicasting, we decided to develop a new network generator and simulator tool with multicasting aspects in focus. We also developed a tool to visualize the networks generated by the simulator and monitor the traffic. The report presents many simulation results that illustrate the significance of different trade-offs between SBT and CBT. Performance characteristics such as delay, join latency, tree size, total traffic and traffic concentration are analysed and examined.

    The conclusion is that each protocol can be preferable in certain scenarios, depending on how important the different parameters are. CBT always performs better than SBT for single source applications if the core can be placed at the sender’s local router. However, this core placement is not necessarily optimal for CBT. The situation is more complex in groups with several sources. There is a trade-off between the scaling problems of SBT and the increased delay and traffic concentration of CBT.

  • 49.
    Berglind, Eilert
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Liu, Liu
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Microwave engineering approach to metallic based photonic waveguides and waveguide components2006In: Proceedings of International Symposium on Biophotonics, Nanophotonics and Metamaterials, 2006, 247-251 p.Conference paper (Refereed)
    Abstract [en]

    Approaches from microwave engineering are used to analyze metallic waveguides and wave-guiding circuits and to point out the usefulness of these techniques in photonics applications, for design of components and to achieve higher densities of integration in integrated photonics circuits than is the case today. It is also find that the losses are severe for certain applications.

  • 50. Bernabé, S.
    et al.
    Stevens, R.
    Volpert, M.
    Hamelin, R.
    Rossat, C.
    Berger, F.
    Lombard, L.
    Kopp, C.
    Berggren, Jesper
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Sundgren, Petrus
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Highly integrated VCSEL-based 10Gb/s miniature optical sub-assembly2005In: Proceedings - Electronic Components and Technology Conference, Lake Buena Vista, FL: IEEE , 2005, Vol. 2, 1333-1338 p.Conference paper (Refereed)
    Abstract [en]

    In order to fit with the present and future needs of the Datacom transceiver market, newly designed high rate transmitter optical subassemblies (TOSAs) have to be compact, low cost and compatible with mass production. We propose here an innovative design strategy that reaches all these targets by integrating a 10Gbps 850nmVCSEL laser diode and its laser driver with other functionalities (e.g. power monitoring and thermal monitoring) in a small form factor package. Taking advantages of the optical properties of the VCSEL and using flip-chip techniques, the transmitter exhibits excellent hyperfrequency performances and compatibility with mass production due to the use of collective manufacturing technologies and passive optical alignment. This versatile approach is also applicable to high rate receivers, parallel optics emitters, and singlemode low cost transmitter integrating long wavelength VCSELs.

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