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  • 101.
    Andersson, Tomas
    KTH, Skolan för elektro- och systemteknik (EES).
    On error-robust source coding with image coding applications2006Licentiatavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    This thesis treats the problem of source coding in situations where the encoded data is subject to errors. The typical scenario is a communication system, where source data such as speech or images should be transmitted from one point to another. A problem is that most communication systems introduce some sort of error in the transmission. A wireless communication link is prone to introduce individual bit errors, while in a packet based network, such as the Internet, packet losses are the main source of error.

    The traditional approach to this problem is to add error correcting codes on top of the encoded source data, or to employ some scheme for retransmission of lost or corrupted data. The source coding problem is then treated under the assumption that all data that is transmitted from the source encoder reaches the source decoder on the receiving end without any errors. This thesis takes another approach to the problem and treats source and channel coding jointly under the assumption that there is some knowledge about the channel that will be used for transmission. Such joint source--channel coding schemes have potential benefits over the traditional separated approach. More specifically, joint source--channel coding can typically achieve better performance using shorter codes than the separated approach. This is useful in scenarios with constraints on the delay of the system.

    Two different flavors of joint source--channel coding are treated in this thesis; multiple description coding and channel optimized vector quantization. Channel optimized vector quantization is a technique to directly incorporate knowledge about the channel into the source coder. This thesis contributes to the field by using channel optimized vector quantization in a couple of new scenarios. Multiple description coding is the concept of encoding a source using several different descriptions in order to provide robustness in systems with losses in the transmission. One contribution of this thesis is an improvement to an existing multiple description coding scheme and another contribution is to put multiple description coding in the context of channel optimized vector quantization. The thesis also presents a simple image coder which is used to evaluate some of the results on channel optimized vector quantization.

  • 102.
    Andersson, Tomas
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Skoglund, Mikael
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    A COVQ-Based image coder for channels with bit errors and erasures2008Ingår i: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 56, nr 2, s. 161-165Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We illustrate how channel optimized vector quantization (COVQ) can be used for channels with both bit-errors and bit-erasures. First, a memoryless channel model is presented, and the performance of COVQ's trained for this channel is evaluated for an i.i.d. Gaussian source. Then, the new method is applied in implementing an error-robust sub-band image coder, and we present image results that illustrate the resulting performance. Our experiments show that the new approach is able to outperform a traditional scheme based on separate source and channel coding.

  • 103. Andersson, Tomas
    et al.
    Skoglund, Mikael
    Händel, Peter
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Frequency estimation by 1-bit quantization and table look-up processing2000Ingår i: Proceedings European Signal Processing Conference, 2000, s. 1807-1810Konferensbidrag (Refereegranskat)
  • 104. Angelopoulos, Constantinos Marios
    et al.
    Nikoletseas, Sotiris
    Raptis, Theofanis P.
    Raptopoulos, Christoforos
    Vasilakis, Filippos
    KTH, Skolan för elektro- och systemteknik (EES).
    Improving sensor network performance with wireless energy transfer2015Ingår i: International Journal of Ad Hoc and Ubiquitous Computing, ISSN 1743-8225, E-ISSN 1743-8233, Vol. 20, nr 3, s. 159-171Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Through recent technology advances in the field of wireless energy transmission wireless rechargeable sensor networks have emerged. In this new paradigm for wireless sensor networks a mobile entity called mobile charger (MC) traverses the network and replenishes the dissipated energy of sensors. In this work we first provide a formal definition of the charging dispatch decision problem and prove its computational hardness. We then investigate how to optimise the trade-offs of several critical aspects of the charging process. In the light of these optimisations, we study the impact of the charging process to the network lifetime for three characteristic underlying routing protocols. Finally, we propose a mobile charging protocol that locally adapts the circular trajectory of the MC to the energy dissipation rate of each sub-region of the network. We compare this protocol against several MC trajectories by a detailed experimental evaluation. The derived findings demonstrate significant performance gains.

  • 105.
    Angulo Barrios, C.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Lourdudoss, Sebastian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT. KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Messmer, L. R.
    Holmgren, M.
    Lovqvist, A.
    Carlsson, C.
    Larsson, A.
    Halonen, J.
    Ghisoni, M.
    Stevens, Renaud
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Schatz, Richard
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP. KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    GaAs/AlGaAs buried-heterostructure laser diodes with semi-insulating GaInP:Fe regrowth2001Ingår i: Lasers and Electro-Optics, 2001. CLEO/Pacific Rim 2001. The 4th Pacific Rim Conference on, 2001, Vol. 2Konferensbidrag (Refereegranskat)
    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.

  • 106.
    Anton-Haro, Caries
    et al.
    Centre Tecnolo`gic de Telecomunicacions de Catalunya (CTTC, Spain).
    Svedman, Patrick
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Bengtsson, Mats
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Alexiou, Angeliki
    Bell Laboratories, Lucent Technologies (United Kingdom).
    Gameiro, Atilio
    University of Aveiro/Istituto de Telecomunicações (Portugal).
    Cross-layer scheduling for multi-user MIMO systems2006Ingår i: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 44, nr 9, s. 39-45Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The increasing demand of wireless services associated with the scarcity of the radio spectrum and the trend to provide end-to-end QoS in emerging and future applications calls for the design of spectrally efficient systems with QoS support. To fulfill these two requirements of spectral efficiency and QoS provision in the highly dynamic environment of mobile radio requires the collaboration of several layers in the system as well as the use of multiple transmit and receive antennas. In a packet network, one important component to achieve the aforementioned efficiency goals is a properly designed scheduling algorithm. Using an information-theoretic framework, we present an overview of the issues associated with the design of packet scheduling algorithms and review several proposed solutions. The article focuses on the advantages of a cross-layer approach to the resource allocation problem and identifies the trade-offs associated with the increased signaling needs. Also, we thoroughly discuss the additional degrees of freedom that multiple transmit and receive antennas can provide.

  • 107. Ao, Xianyu
    et al.
    Liu, Liu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Wosinski, Lech
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    He, Sailing
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Polarization beam splitter based on a two-dimensional photonic crystal of pillar type2006Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Applied physics letters, Vol. 89, nr 17, s. 171115-Artikel i tidskrift (Refereegranskat)
    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.

  • 108.
    Apanasevic, Tatjana
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab). KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, KTH Center för Trådlösa System, Wireless@kth.
    Factors Influencing the Slow Rate of Penetration of NFC Mobile Payment in Western Europe2013Ingår i: the 12th International Conference on Mobile Business (ICMB2013), Berlin, Germany, June 2013, 2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    The NFC technology implemented on the base of contemporary mobile handsets can provide considerable benefits to end-users. However, despite high level of diffusion of mobile phones in Western Europe, the level of penetration of the NFC based mobile payment is low. A considerable number of trials have been initiated, however, large scale deployment of commercial NFC services cannot be seen. This paper identifies and analyzes different factors that influence the slow rate of penetration of NFC based mobile payment in Western Europe.

    This paper presents a qualitative study based on experience of six NFC pilots implemented in Finland, France, Italy, the Netherlands, Norway, and the UK. The research findings confirm that a number of demand and supply barriers negatively affect the rate of the penetration of the NFC payment. The network externalities and the lack of consumer awareness about NFC services were identified as the most important demand side barriers. The most significant supply side barriers are the lack of uniform technological standards, the lack of NFC enabled mobile phones, and the coopetition issue. In addition, the interrelation between mentioned obstacles was identified. This fact means that a delay in the NFC payment’s diffusion is affected not by a single factor, but rather by a set of interrelated factors. The sources of these obstacles are related to the consumer acceptance, the specifics of business environment, and the technology.

  • 109.
    Apanasevic, Tatjana
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab). KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, KTH Center för Trådlösa System, Wireless@kth.
    Mobile Payments: Main Trends in the Retail Industry2014Ingår i: 25th European Regional Conference of the International Telecommunications Society (ITS), Brussels, Belgium, June 22 - 25, 2014, 2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    The main objective of the ongoing study is to investigate obstacles ans driving forces affecting organization adoption of innovation. In order to that an example of the mobile payments applied in the Swedish retail industry has been used. The main analyzed factors are: adopter characteristics, supplier marketing activity, perceived innovation dcharacteristics, social network, and environmental influences.

    The analysis of case study findings helped to estimate some common trends in the adoption of mobile payment services by retailers. As a result, the analyzed factors were categorized as obstacles or driving forces to adoption of the mobile payments.

  • 110.
    Apanasevic, Tatjana
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab). KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, KTH Center för Trådlösa System, Wireless@kth.
    Organizational Acceptance of Mobile Payments2014Ingår i: 30th annual International Marketing and Purchasing Conference (IMP 2014), Bordeaux, France, September 4-5, 2014, 2014Konferensbidrag (Refereegranskat)
  • 111.
    Apanasevic, Tatjana
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab). KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, KTH Center för Trådlösa System, Wireless@kth.
    The Effect of Innovation on Business Networks2014Konferensbidrag (Refereegranskat)
  • 112.
    Apanasevic, Tatjana
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab). KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, KTH Center för Trådlösa System, Wireless@kth.
    Markendahl, Jan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, KTH Center för Trådlösa System, Wireless@kth. KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Stakeholder’s expectations: Mobile payments in retail in Sweden2014Ingår i: 13th International Conference on Mobile Business, 2014 (ICMB 2014), London, June 4-5, 2014, 2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    One of the main application areas of mobile payment services in Sweden is retailing. The main stakeholders involved in this service are mobile payment service providers, banks, merchants, and consumers. The main focus of this paper is on the change of expectations of different stakeholders taking part in service provisioning. Analysis has been performed by comparison of the initial expectations before the introduction of a mobile payment service and expectations after practical experience of the service usage. Three cases of mobile payment solutions for retailing have been investigated: BART provided by Swedbank, SEQR provided by Seamless, and a service provided by Payair.

    The analysis indicates that a number of expectations of stakeholders about mobile payment services did not come true. The results for the different cases differ but the main findings are: banks were excluded from direct service provisioning; merchants see some advantaged to deploy mobile payment, but are uncertain which solution will be a dominant in the market; consumer expectations of improved purchasing experience and usefulness are not met. The performed analysis also helps to identify some of the reasons that can be seen as obstacles for a wider penetration of mobile payment services.

  • 113.
    Apanasevic, Tatjana
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab). KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, KTH Center för Trådlösa System, Wireless@kth.
    Markendahl, Jan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, KTH Center för Trådlösa System, Wireless@kth. KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Arvidsson, Niklas
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekonomi och organisation (Inst.), Entreprenörskap och Innovation.
    Stakeholder’s expectations: The case of mobile public transport ticketing in Sweden2014Ingår i: 13th International Conference on Mobile Business, 2014 (ICMB 2014), London, June 4-5, 2014, 2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    One of the main areas of mobile payment application in Sweden is mobile public transport ticketing. The main stakeholders involved in this service are mobile network operators, mobile payment service providers, SMS ticket’s “technology solution” providers, public transport companies, and consumers.

    Traditionally, mobile operators have had a strong position in this niche since the mobile phone bill or pre-paid subscriptions were used for end-user billing. Due to financial regulation, this situation was changed in February 2013 when new SMS payment solutions were introduced for all public transport companies in Sweden. A number of new actors entered the scene, and the position of existing actors changed dramatically. At the same time, the Swedish mobile operators formed a joint venture, 4T Sweden, offering a new mobile payment solution – WyWallet.

    The main focus of this paper is on the change of expectations of different stakeholders taking part in provisioning of SMS payment services. Analysis has been performed by comparison of the initial expectations before the introduction of the new SMS payment system and the real outcome in approximately half a year time. Analysis revealed the fact that expectations of a number of stakeholders about mobile payment services did not come true. Moreover, due to barriers set by the mobile payment solution, mobile payment transactions in public transportation is dramatically lower than what SMS payments were before the market changed.

  • 114. Aparicio Pardo, Ramon
    et al.
    Garcia Manrubia, Belen
    Pavon Marino, Pablo
    Skorin-Kapov, Nina
    Furdek, Marija
    Balancing CapEx reduction and network stability with stable routing-virtual topology capacity adjustment (SR-VTCA)2013Ingår i: Optical Switching and Networkning Journal, ISSN 1573-4277, E-ISSN 1872-9770, Vol. 10, nr 4, s. 343-353Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper investigates the merits of the SR–VTCA (stable routing–virtual topology capacity adjustment) approach as a mechanism to find a beneficial trade-off between network stability and reduction in capital expenditures (CapEx). These are two main objectives for the entities that own the optical infrastructure, such as network operators (NOs), and those also acting as Internet service providers (ISPs). The SR–VTCA scheme is a novel approach to adapt transparent optical networks to time-varying traffic by adjusting the number of lightpaths between node pairs, while keeping the IP routing unchanged. Lightpath bundling (LB) and anycast (AS) switching are combined in SR–VTCA operation to advertise lightpath additions/removals to the IP layer as mere adjustments (increments or decrements) in the capacity, allowing to keep the IP routing stable, and thus, simplifying control plane operations. On the contrary, a fully-reconfigurable (FR) network design, where IP routing can be also modified, would increase the burden in the control plane, but at a higher CapEx reduction, since the optical infrastructure is used more efficiently. In this work, we investigate the CapEx overprovision introduced by SR–VTCA with respect to a FR scheme. In order to do this, SR–VTCA planning problem is first modeled as a MILP formulation. A heuristic procedure based on traffic domination is then proposed to solve large instances of the problem. Exhaustive experiments are conducted comparing the SR–VTCA solutions obtained by the aforementioned MILP and heuristic proposal with solutions found by other optimization methods presented in the literature to solve the FR planning problem. Finally, the results show that SR–VTCA can achieve similar results to the FR case in terms of CapEx reduction, while a huge number of IP reroutings are saved by maintaining IP stability. Thus, SR–VTCA provides an advantageous balance between CapEx overprovisioning and the control plane overhead associated with IP rerouting.

  • 115.
    Arapoglou, Pantelis-Daniel
    et al.
    University of Luxembourg, Luxembourg.
    Shankar, M. R. Bhavani
    University of Luxembourg, Luxembourg.
    Panagopoulos, Athanasios
    University of Luxembourg, Luxembourg.
    Ottersten, Björn
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Gateway Diversity Strategies in Q/V Band Feeder Links2011Ingår i: Proceedings 17th Ka and Broadband Communications Conference, 2011Konferensbidrag (Refereegranskat)
  • 116. Archambault, Emile
    et al.
    Alloune, Nabih
    Furdek, Marija
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Xu, Zhenyu
    Tremblay, Christine
    Muhammad, Ajmal
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Chen, Jiajia
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Wosinska, Lena
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Kommunikationssystem, CoS, Optical Network Laboratory (ON Lab).
    Littlewood, Paul
    Belanger, Michel
    Routing and spectrum assignment in elastic filterless optical networks2016Ingår i: IEEE/ACM Transactions on Networking, ISSN 1063-6692, E-ISSN 1558-2566, Vol. 24, nr 6, s. 3578-3592Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Elastic optical networking is considered a promising candidate to improve the spectral efficiency of optical networks. One of the most important planning challenges of elastic optical networks is the NP-hard routing and spectrum assignment (RSA) problem. In this paper, we investigate offline RSA in elastic filterless optical networks, which use a passive broadcast-and-select architecture to offer network agility. Here elastic optical network is referred to as the optical network that can adapt the channel bandwidth, data rate, and transmission format for each traffic demand in order to offer maximum throughput. In elastic filterless networks, the presence of unfiltered signals resulting from the drop-and-continue node architecture must be considered as an additional constraint in the RSA problem. In this paper, first the RSA problem in elastic filterless networks is formulated by using integer linear program (ILP) to obtain optimal solutions for small networks. Due to the problem complexity, two efficient RSA heuristics are also proposed to achieve suboptimal solutions for larger networks in reasonable time. Simulation results show that significant bandwidth savings in elastic filterless networks can be achieved compared to the fixed-grid filterless solutions. The proposed approach is further tested in multi-period traffic scenarios and combined with periodical spectrum defragmentation, leading to additional improvement in spectrum utilization of elastic filterless optical networks.

  • 117.
    Ardah, Khaled
    et al.
    Univ Fed Ceara, Wireless Telecom Res Grp, BR-60440970 Fortaleza, Ceara, Brazil..
    Fodor, Gabor
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik. Ericsson Res, Radio Dept, S-16480 Stockholm, Sweden.
    Silva, Yuri C. B.
    Univ Fed Ceara, Wireless Telecom Res Grp, BR-60440970 Fortaleza, Ceara, Brazil..
    Freitas, Walter C., Jr.
    Univ Fed Ceara, Wireless Telecom Res Grp, BR-60440970 Fortaleza, Ceara, Brazil..
    Cavalcanti, Francisco R. P.
    Univ Fed Ceara, Wireless Telecom Res Grp, BR-60440970 Fortaleza, Ceara, Brazil..
    A Novel Cell Reconfiguration Technique for Dynamic TDD Wireless Networks2018Ingår i: IEEE Wireless Communications Letters, ISSN 2162-2337, E-ISSN 2162-2345, Vol. 7, nr 3, s. 320-323Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In dynamic time division duplexing (DTDD) systems, the uplink (UL) and downlink (DL) resources can be configured to adapt to changing traffic conditions. Therefiwe, DTDD systems are advantageously deployed in scenarios in which the UL and DL traffic demands are asymmetric and timevarying. Unfortunately, multicell DTDD systems give rise to base station-to-base station and user equipment-to-user equipment interference, that can severely degrade the system performance. Previous works on DTDD either assumed that the UL/DL configurations are given, or they did not take into account the negative impact of multicell DTDD interference. In this letter, we propose a novel cell reconfiguration technique that considers both the prevailing traffic conditions and multicell interference levels. The proposed technique is based on an efficient solution of a mixed integer linear program, whose objective is to maximize the overall system throughput taking into account users' traffic preferences. Realistic system level simulations indicate that the proposed scheme outperforms not only the static TDD system but also other reference schemes, that disregard the DTDD specific interference effects.

  • 118. Asghar, Muhammad Rizwan
    et al.
    Dan, György
    KTH, Skolan för elektro- och systemteknik (EES), Nätverk och systemteknik.
    Miorandi, Daniele
    Chlamtac, Imrich
    Smart Meter Data Privacy: A Survey2017Ingår i: IEEE Communications Surveys and Tutorials, ISSN 1553-877X, E-ISSN 1553-877X, Vol. 19, nr 4, s. 2820-2835Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Automated and smart meters are devices that are able to monitor the energy consumption of electricity consumers in near real-time. They are considered key technological enablers of the smart grid, as the real-time consumption data that they can collect could enable new sophisticated billing schemes, could facilitate more efficient power distribution system operation and could give rise to a variety of value-added services. At the same time, the energy consumption data that the meters collect are sensitive consumer information; thus, privacy is a key concern and is a major inhibitor of real-time data collection in practice. In this paper, we review the different uses of metering data in the smart grid and the related privacy legislation. We then provide a structured overview, shortcomings, recommendations, and research directions of security solutions that are needed for privacy-preserving meter data delivery and management. We finally survey recent work on privacy-preserving technologies for meter data collection for the three application areas: 1) billing; 2) operations; and 3) value-added services including demand response.

  • 119. Ashraf, Shehzad Ali
    et al.
    Wang, Y.-P. Eric
    Eldessoki, Sameh
    Holfeld, Bernd
    Parruca, Donald
    Serror, Martin
    Gross, James
    KTH, Skolan för elektro- och systemteknik (EES), Teknisk informationsvetenskap.
    From Radio Design to System Evaluations for Ultra-Reliable and Low-Latency Communication2017Ingår i: European Wireless 2017 - 23rd European Wireless Conference, 2017, artikel-id 8011336Konferensbidrag (Refereegranskat)
    Abstract [en]

    Ultra-reliable and low-latency communication is the enabler for many new use cases, including wireless industrial automation. Fulfilling varying requirements of these use cases demands a flexible radio design. To address this, a holistic approach needs to be adopted. Therefore, this paper presents the radio access concepts affecting the communication reliability and latency, and comprehensively evaluates link and system level considerations through simulations. In particular, we describe the choice of suitable modulation and coding schemes, and discuss the impact of different numerologies and waveform candidates. We also point out the key principles for radio frame design to reduce the end-to-end latency. The presented concepts are then used to evaluate the performance at system level for an industrial scenario. It is shown that by an appropriate design of the radio interface for 5G system, the required low-latency and high reliability for industrial applications and many other use cases can be achieved.

  • 120.
    Asplund, Henrik
    et al.
    Ericsson Research.
    Alayon Glazunov, Andres
    Ericsson Research.
    Berg, Jan-Erik
    Ericsson Research.
    An investigation of measured and simulated wideband channels with applications to 1.25 MHz and 5 MHz CDMA systems1998Konferensbidrag (Refereegranskat)
  • 121.
    Asplund, Henrik
    et al.
    Ericsson Research.
    Alayon Glazunov, Andres
    Ericsson Research.
    Molisch, Andreas F.
    Nachrichtentechnik und Höchfrequenztechnik (INTHF) of the TU Wien.
    Pedersen, Klaus I.
    Aalborg University.
    Steinbauer, Martin
    Nachrichtentechnik und Höchfrequenztechnik (INTHF) of the TU Wien.
    The COST 259 Directional Channel Model-Part II: Macrocells2006Ingår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 5, nr 12, s. 3434-3450Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper describes the attributes of the COST 259 directional channel model that are applicable for use in the design and implementation of macrocellular mobile and portable radio systems and associated technology. Special care has been taken to model all propagation mechanisms that are currently understood to contribute to the characteristics of practical macrocellular channels and confirm that large scale, small scale, anddirectional characteristics of implemented models are realistic through their comparison with available measured data. The model that is described makes full use of previously published work, as well as incorporating some new results. It is considered that its implementation should contribute to a tool that can be used for simulations and comparison of different aspects of a large variety of wireless communication systems, including those that exploit the spatial aspects of radio channels, as, for example, throughthe use of adaptive antenna systems. 

  • 122.
    Astély, David
    et al.
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Ottersten, Björn
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Constrained Complexity Spatio-Temporal Interference Rejection Combining1999Ingår i: Proceedings of SPAWC’99, Signal Processing Advances in Wireless Communications, IEEE , 1999, s. 110-113Konferensbidrag (Refereegranskat)
    Abstract [en]

    Space-time processing for co-channel interference (CCI) rejection and equalization with antenna arrays may provide large gains over space-only processing, especially in interference limited scenarios. However, taking thetemporal correlation of the noise and CCI process into account leads to sequence detection with highercomplexity as compared to space-only processing that neglects this correlation. We propose the use of the generalized Viterbi algorithm for sequence detection with lower complexity. Special cases include the M-algorithm and the delayed decision feedback sequence estimator. A relevant comparison between spatial andspatio-temporal processing with sequence detectors of the same complexity may thus be performed. Numerical examples show substantial gains for spatio-temporal processing as compared to space-only processing also in this case when the optimality of the sequence detector is traded for interference rejection.

  • 123.
    Astély, David
    et al.
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Ottersten, Björn
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    MLSE and Spatio-Temporal Interference Rejection Combining with Antenna Arrays1998Ingår i: Proceedings of Eusipco-98, Ninth European Signal Processing Conference, Island of Rhodes, Greece, 1998, s. 1341-1344Konferensbidrag (Refereegranskat)
  • 124.
    Astély, David
    et al.
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Ottersten, Björn
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    On Spatio-Temporal Interference Rejection Combining with Antenna Arrays1998Övrigt (Refereegranskat)
  • 125.
    Astély, David
    et al.
    Ericsson Research.
    Ottersten, Björn
    KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
    Spatio-Temporal Interference Rejection Combining2005Ingår i: Smart Antennas - State-of-the-Art / [ed] Kaiser, Thomas, Hindawi Publishing Corporation , 2005, s. 5-26Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 126.
    Asztély, David
    et al.
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Bengtsson, Mats
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Kristensson, Martin
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Ottersten, Björn
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Spatio-Temporal Processing for Wireless Communications1998Ingår i: First Annual UCSD Conference on Wireless Communications, 1998Konferensbidrag (Refereegranskat)
  • 127.
    Asztély, David
    et al.
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Ottersten, Björn
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    The Effects of Local Scattering on Direction of Arrival Estimation with MUSIC and ESPRIT1998Ingår i: Acoustics, Speech and Signal Processing, ICASSP 98., IEEE , 1998, s. 3333-3336Konferensbidrag (Refereegranskat)
    Abstract [en]

    In wireless communication scenarios, multipath propagation from local scatterers in the vicinity of mobile sources may cause angular spreading as seen from a base station antenna array. This paper studies the effects of suchlocal scattering on direction of arrival (DOA) estimation with the MUSIC and ESPRIT algorithms. Previous work has considered rapidly time-varying scenarios, and concluded that local scattering has a minor effect on DOAestimation in such scenarios. This work considers the case in which the channel is time-invariant during theobservation period. The distribution of the DOA estimates is derived, and the results show that local scatteringhas a significant impact on DOA estimation in the time-invariant case. In addition, numerical examples are included to illustrate the analysis, and to demonstrate that the results may be used to formulate simple estimators of angular spread.

  • 128.
    Asztély, David
    et al.
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Ottersten, Björn
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Swindlehurst, Andrew Lee
    Department of Electrical and Computer Engineering, Brigham Young University, Provo, UT 84602 USA.
    Generalised Array Manifold Model for Wireless Communication Channels with Local Scattering1998Ingår i: IEE Proceedings Radar, Sonar and Navigation, ISSN 1350-2395, Vol. 145, nr 1, s. 51-57Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The authors propose the use of a generalised array manifold for parameterised spatial signature estimation in wireless communication channels with local scattering. The array manifold commonly used for point sources is generalised to include linear combinations of the nominal array response vectors and their derivatives. The motivation behind this idea is to obtain better estimates of the spatial signatures for direction of arrival (DOA) based signal waveform estimation. The estimators proposed exploit the orthogonality between the so-called noise and signal subspaces, leading to a separable solution for the derivative coefficients. As a result, a search is required for the DOAs only. For uniform linear arrays, the spatial signatures are shown to be approximately Vandermonde vectors with damped modes, and a closed-form estimator such as ESPRIT may be used in this case. Simulation examples are included to compare the signal estimation performance obtained using the proposed generalised manifold and the conventional array manifold.

  • 129.
    Asztély, David
    et al.
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    Swindlehurst, Andrew Lee
    Department of Electrical and Computer Engineering, Brigham Young University, Provo, UT 84602 USA.
    Ottersten, Björn
    KTH, Tidigare Institutioner, Signaler, sensorer och system.
    A Generalized Array Manifold Model for Local Scattering in Wireless Communications1997Ingår i: Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing. ICASSP-97, IEEE , 1997, s. 4021-4024Konferensbidrag (Refereegranskat)
    Abstract [en]

    In wireless communication scenarios, local scatterers in the vicinity of the mobile sources cause angular spreading. As a result, the spatial signatures will not belong to the conventional array manifold parameterized by direction of arrival (DOA) alone. A parameterized model for spatial signatures applicable in scenarios with localscattering is presented. Several algorithms that exploit this model are proposed, and the performance of signal waveform estimators using the model is investigated via simulations. It is demonstrated that considerable gain may result as compared with using the conventional plane wave model.

  • 130.
    Athanasiou, George
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Tassiulas, Leandros
    Design and implementation of distributed load balancing and fast handoff for wireless mesh networks2015Ingår i: European transactions on telecommunications, ISSN 1124-318X, E-ISSN 2161-3915, Vol. 26, nr 4, s. 630-649Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The association/handoff procedures are very important towards achieving a balanced operation in 802.11-based wireless mesh networks. In this paper, we design and implement a cooperative association/handoff scheme, where stations share useful information, and handoff is executed in a seamless manner. Furthermore, we introduce a cross-layer load balancing mechanism that takes into account uplink and downlink channel conditions, routing performance and congestion control. The proposed heuristic algorithms are inspired by the rapidly designed cooperative protocols and control the communication load of each mesh access point in a distributed manner. We evaluate the performance of our mechanisms through OPNET () simulations and testbed experiments. Copyright (c) 2013 John Wiley & Sons, Ltd.

  • 131.
    Atiiq, Syafiq Al
    KTH, Skolan för elektro- och systemteknik (EES), Nätverk och systemteknik.
    Adaptive Counteraction Against Denial of Service Attack2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Sakernas Internet (IoT) är nästa generations nätverkssamhälle där miljarder av, vardagliga, enheter är direkt anslutna till Internet och har möjlighet att kommunicera med varandra. Särskilt har CoAP, ett lättviktsprotokoll för webbtrafik som även fungerar för plattformar med begränsade resurser, blivit Sakernas Internets standard för kommunikation på applikationslagret. Men eftersom IoT-enheter är direkt anslutna till Internet så är de också speciellt utsatta för ett antal säkerhetsattacker, inklusive DoS, som kan försämra deras prestanda och mottaglighet avsevärt och i värsta fall göra dem helt otillgängliga för legitima förfrågningar.

    I detta examensarbete har vi utvecklat en lageröverskridande och kontextmedveten metod som adaptivt motverkar DoS attacker mot CoAP serverenheter genom att dynamiskt anpassa enhetens operativa tillstånd i enlighet med attackintensiteten. Detta begränsar DoS-attackers påverkan på enheterna avsevärt samtidigt som det bibehåller tillgänglighet för tjänster på utsatta enheter till största möjliga utsträckning. Den föreslagna metoden utnyttjar en betrodd proxy som adaptivt skyddar utsatta enheter, samtidigt som den effektivt vidarebefordrar och sparar meddelanden om så behövs. I detta arbete har vi skapat en proof of concept-implementation av vår lösning för Californium-ramverket och CoAP protokollet. Arbetet har utvärderats experimentellt för att undersöka lösningens effektivitet när det gäller att motarbeta DoS-attacker samt hur den bibehåller enheters tillgänglighet under attacker.

    Detta uppsatsprojekt har utförts i samarbete med RISE SICS som är ett forskningsinstitut för tillämpad informations- och kommunikationsteknik i Sverige.

  • 132.
    Azari, Amin
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Cavdar, Cicek
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Kommunikationssystem, CoS, Radio Systems Laboratory (RS Lab).
    Performance Evaluation and Optimization of LPWA IoT Networks: A Stochastic Geometry Approach2018Ingår i: 2018 IEEE Global Communications Conference, GLOBECOM 2018 - Proceedings, IEEE, 2018, artikel-id 8647881Konferensbidrag (Refereegranskat)
    Abstract [en]

    Leveraging grant-free radio access for enabling low-power wide-area (LPWA) Internet of Things (IoT) connectivity has attracted lots of attention in recent years. Regarding lack of research on LPWA IoT networks, this work is devoted to reliability modeling, battery-lifetime analysis, and operation-control of such networks. We derive the interplay amongst density of the access points, communication bandwidth, volume of traffic from heterogeneous sources, and quality of service (QoS) in communications. The presented analytical framework comprises modeling of interference from heterogeneous sources with correlated deployment locations and time-frequency asynchronous radio-resource usage patterns. The derived expressions represent the operation regions and rates in which, energy and cost resources of devices and the access network, respectively, could be traded to achieve a given level of QoS in communications. For example, our expressions indicate the expected increase in QoS by increasing number of transmitted replicas, transmit power, density of the access points, and communication bandwidth. Our results further shed light on scalability of such networks and figure out the bounds up to which, scaling resources can compensate the increase in traffic volume and QoS demand. Finally, we present an energy-optimized operation control policy for IoT devices. The simulation results confirm tightness of the derived analytical expressions, and indicate usefulness of them in planning and operation control of IoT networks.

  • 133. Azmi, Marwan H.
    et al.
    Yuan, Jinhong
    Lechner, Gottfried
    Rasmussen, Lars Kildehöj
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Design of Multi-Edge-Type Bilayer-Expurgated LDPC Codes for Decode-and-Forward in Relay Channels2011Ingår i: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 59, nr 11, s. 2993-3006Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We consider the design of bilayer-expurgated low-density parity-check (BE-LDPC) codes as part of a decode-and-forward protocol for use over the full-duplex relay channel. A new ensemble of codes, termed multi-edge-type bilayer-expurgated LDPC (MET-BE-LDPC) codes, is introduced where the BE-LDPC code design problem is transformed into the problem of optimizing the multinomials of a multi-edge-type LDPC code. We propose two design strategies for optimizing MET-BE-LDPC codes; the bilayer approach is preferred when the difference in SNR between the source-to-relay and the source-to-destination channels is small, while the bilayer approach with intermediate rates is preferred when this difference is large. In both proposed design strategies multi-edge-type density evolution is used for code optimization. The resulting MET-BE-LDPC codes exhibit improved threshold and bit-error-rate performance as compared to previously reported bilayer LDPC codes.

  • 134.
    B. da Silva Jr., Jose Mairton
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Optimization and Fundamental Insights in Full-Duplex Cellular Networks2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The next generations of cellular networks are expected to provide explosive data rate transmissions and very low latencies. To meet such demands, one of the promising wireless transmissions candidates is in-band full-duplex communications, which enable wireless devices to simultaneously transmit and receive on the same frequency channel. Full-duplex communications have the potential to double the spectral efficiency and reduce the transmission delays when compared to current half-duplex systems that either transmit or receive on the same frequency channel. Until recently, full-duplex communications have been hindered by the interference that leaks from the transmitter to its own receiver,the so-called self-interference. However, advances in digital and analog self-interference suppression techniques are making it possible to reduce the self-interference to manageable levels, and thereby make full-duplex a realistic candidate for advanced wireless systems.

    Although in-band full-duplex promises to double the data rates of existing wireless technologies, its deployment in cellular networks must be gradual due to the large number of legacy devices operating in half-duplex mode. When half-duplex devices are deployed in full-duplex cellular networks, the user-to-user interference may become the performance bottleneck. In such new interference situation, the techniques such as user pairing, frequency channel assignment, power control, beamforming, and antenna splitting become even more important than before, because they are essential to mitigate both the user-to-user interference and the residual self-interference. Moreover, introduction of full- duplex in cellular networks must comply with current multi-antenna systems and, possibly, transmissions in the millimeter-wave bands. In these new scenarios, no comprehensive analysis is available to understand the trade-offs in the performance of full-duplex cellular networks.

    This thesis investigates the optimization and fundamental insights in the design of spectral efficient and fair mechanisms in full-duplex cellular networks. The novel analysis proposed in this thesis suggests new solutions for maximizing full-duplex performance in the sub-6 GHz and millimeter-wave bands. The investigations are based on an optimization theory approach that includes distributed and nonconvex optimization with mixed integer-continuous variables, and novel extensions of Fast-Lipschitz optimization. The analysis sheds lights on fundamental questions such as which antenna architecture should be used and whether full-duplex in the millimeter-wave band is feasible. The results establish fundamental insights in the role of user pairing, frequency assignment, power control and beamforming; reveal the special behaviour between the self-interference and user- to-user interference; analyse the trade-offs between antenna sharing and splitting for uplink/downlink signal separation; and investigate the role of practical beamforming design in full-duplex millimeter-wave systems. This thesis may provide input to future standardization process of full-duplex communications.

  • 135.
    B. da Silva Jr., Jose Mairton
    KTH, Skolan för elektro- och systemteknik (EES), Nätverk och systemteknik.
    Spectral Efficiency and Fairness Maximization in Full-Duplex Cellular Networks2017Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Future cellular networks, the so-called 5G, are expected to provide explosive data volumes and data rates. To meet such a demand, the research communities are investigating new wireless transmission technologies. One of the most promising candidates is in-band full-duplex communications. These communications are characterized by that a wireless device can simultaneously transmit and receive on the same frequency channel. In-band full-duplex communications have the potential to double the spectral efficiencywhen compared to current half duplex systems. The traditional drawback of full-duplex was the interference that leaks from the own transmitter to its own receiver, the so- called self-interference, which renders the receiving signal unsuitable for communication.However, recent advances in self-interference suppression techniques have provided high cancellation and reduced the self-interference to noise floor levels, which shows full-duplex is becoming a realistic technology component of advanced wireless systems.

    Although in-band full-duplex promises to double the data rate of existing wireless technologies, its deployment in cellular networks is challenging due to the large number of legacy devices working in half-duplex. A viable introduction in cellular networks is offered by three-node full-duplex deployments, in which only the base stations are full-duplex, whereas the user- or end-devices remain half-duplex. However, in addition to the inherent self-interference, now the interference between users, the user-to-user interference, may become the performance bottleneck, especially as the capability to suppress self-interference improves. Due to this new interference situation, user pairing and frequency channel assignment become of paramount importance, because both mechanisms can help to mitigate the user-to-user interference. It is essential to understand the trade-offs in the performance of full-duplex cellular networks, specially three-node full-duplex, in the design of spectral and energy efficient as well as fair mechanisms.

    This thesis investigates the design of spectral efficient and fair mechanisms to improve the performance of full-duplex in cellular networks. The novel analysis proposed in this thesis suggests centralized and distributed user pairing, frequency channel assignment and power allocation solutions to maximize the spectral efficiency and fairness in future full-duplex cellular networks. The investigations are based on distributed optimization theory with mixed integer-real variables and novel extensions of Fast-Lipschitz optimization. The analysis sheds lights on two fundamental problems of standard cellular networks, namely the spectral efficiency and fairness maximization, but in the new context of full-duplex communications. The results in this thesis provide important understanding in the role of user pairing, frequency assignment and power allocation, and reveal the special behaviourbetween the legacy self-interference and the new user-to-user interference. This thesis can provide input to the standardization process of full-duplex communications, and have the potential to be used in the implementation of future full-duplex in cellular networks.

  • 136.
    B. da Silva Jr., Jose Mairton
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Nätverk och systemteknik.
    Fodor, Gabor
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. Ericsson Research.
    Fischione, Carlo
    KTH, Skolan för elektro- och systemteknik (EES), Nätverk och systemteknik.
    Fast-Lipschitz Power Control and User-Frequency Assignment in Full-Duplex Cellular Networks2017Ingår i: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 16, nr 10, s. 6672-6687Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In cellular networks, the three-node full-duplex transmission mode has the po-tential to increase spectral efficiency without requiring full-duplex capability ofusers. Consequently, three-node full-duplex in cellular networks must deal with self-interference and user-to-user interference, which can be managed by power controland user-frequency assignment techniques. This paper investigates the problem ofmaximizing the sum spectral efficiency by jointly determining the transmit powersin a distributed fashion, and assigning users to frequency channels. The problem is for-mulated as a mixed-integer nonlinear problem, which is shown to be non-deterministicpolynomial-time hard. We investigate a close-to-optimal solution approach by dividingthe joint problem into a power control problem and an assignment problem. The powercontrol problem is solved by Fast-Lipschitz optimization, while a greedy solution withguaranteed performance is developed for the assignment problem. Numerical resultsindicate that compared with the half-duplex mode, both spectral and energy efficienciesof the system are increased by the proposed algorithm. Moreover, results show that thepower control and assignment solutions have important, but opposite roles in scenarioswith low or high self-interference cancellation. When the self-interference cancellationis high, user-frequency assignment is more important than power control, while powercontrol is essential at low self-interference cancellation.

  • 137.
    B. da Silva Jr., Jose Mairton
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Nätverk och systemteknik.
    Fodor, Gabor
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. Ericsson Research.
    Fischione, Carlo
    KTH, Skolan för elektro- och systemteknik (EES), Nätverk och systemteknik.
    On the Spectral Efficiency and Fairness in Full-Duplex Cellular Networks2017Ingår i: 2017 IEEE International Conference on Communications (ICC), Paris: Institute of Electrical and Electronics Engineers (IEEE), 2017, s. 1-6, artikel-id 7996391Konferensbidrag (Refereegranskat)
    Abstract [en]

    To increase the spectral efficiency of wireless networks without requiring full-duplex capability of user devices, a potential solution is the recently proposed three-node full-duplex mode. To realize this potential, networks employing three-node full-duplex transmissions must deal with self-interference and user-to-user interference, which can be managed by frequency channel and power allocation techniques. Whereas previous works investigated either spectral efficient or fair mechanisms, a scheme that balances these two metrics among users is investigated in this paper. This balancing scheme is based on a new solution method of the multi-objective optimization problem to maximize the weighted sum of the per-user spectral efficiency and the minimum spectral efficiency among users. The mixed integer non-linear nature of this problem is dealt by Lagrangian duality. Based on the proposed solution approach, a low-complexity centralized algorithm is developed, which relies on large scale fading measurements that can be advantageously implemented at the base station. Numerical results indicate that the proposed algorithm increases the spectral efficiency and fairness among users without the need of weighting the spectral efficiency. An important conclusion is that managing user-to-user interference by resource assignment and power control is crucial for ensuring spectral efficient and fair operation of full-duplex networks.

  • 138.
    B. da Silva Jr., Jose Mairton
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Ghauch, Hadi
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Fodor, Gabor
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik.
    Fischione, Carlo
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    How to Split UL/DL Antennas in Full-DuplexCellular Networks2018Ingår i: IEEE International Conference on Communication (ICC’18): ThirdWorkshop on Full-Duplex Communications for Future Wireless Networks, Kansas City, MO, USA: IEEE Communications Society, 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    To further improve the potential of full-duplex com-munications, networks may employ multiple antennas at thebase station or user equipment. To this end, networks thatemploy current radios usually deal with self-interference andmulti-user interference by beamforming techniques. Althoughprevious works investigated beamforming design to improvespectral efficiency, the fundamental question of how to split theantennas at a base station between uplink and downlink infull-duplex networks has not been investigated rigorously. Thispaper addresses this question by posing antenna splitting as abinary nonlinear optimization problem to minimize the sum meansquared error of the received data symbols. It is shown that thisis an NP-hard problem. This combinatorial problem is dealt withby equivalent formulations, iterative convex approximations, anda binary relaxation. The proposed algorithm is guaranteed toconverge to a stationary solution of the relaxed problem with muchsmaller complexity than exhaustive search. Numerical resultsindicate that the proposed solution is close to the optimal in bothhigh and low self-interference capable scenarios, while the usuallyassumed antenna splitting is far from optimal. For large numberof antennas, a simple antenna splitting is close to the proposedsolution. This reveals that the importance of antenna splittingdiminishes with the number of antennas.

  • 139.
    B. da Silva Jr., Jose Mairton
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Nätverk och systemteknik.
    Ghauch, Hadi
    Fodor, Gabor
    Skoglund, Mikael
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Teknisk informationsvetenskap.
    Fischione, Carlo
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Smart Antenna Assignment is Essential in Full-Duplex Communications2019Ingår i: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Full-duplex communications have the potential to almost double the spectralefficiency. To realize such a potentiality, the signal separation at base station’s antennasplays an essential role. This paper addresses the fundamentals of such separationby proposing a new smart antenna architecture that allows every antenna to beeither shared or separated between uplink and downlink transmissions. The benefitsof such architecture are investigated by an assignment problem to optimally assignantennas, beamforming and power to maximize the weighted sum spectral efficiency.We propose a near-to-optimal solution using block coordinate descent that divides theproblem into assignment problems, which are NP-hard, a beamforming and powerallocation problems. The optimal solutions for the beamforming and power allocationare established while near-to-optimal solutions to the assignment problems are derivedby semidefinite relaxation. Numerical results indicate that the proposed solution isclose to the optimum, and it maintains a similar performance for high and low residualself-interference powers. With respect to the usually assumed antenna separationtechnique and half-duplex transmission, the sum spectral efficiency gains increase withthe number of antennas. We conclude that our proposed smart antenna assignment forsignal separation is essential to realize the benefits of multiple antenna full-duplexcommunications.

  • 140.
    B. da Silva Jr., Jose Mairton
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Sabharwal, Ashutosh
    Rice University.
    Fodor, Gabor
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik.
    Fischione, Carlo
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Nätverk och systemteknik.
    Low Resolution Phase Shifters Suffice for Full-Duplex mmWave Communications2019Ingår i: IEEE International Conference on Communications: Workshop on Full-Duplex Communications for Future Wireless Networks, Shangai, China: IEEE Communications Society, 2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    Full-duplex base-stations with half-duplex nodes,allowing simultaneous uplink and downlink from different nodes,have the potential to double the spectrum efficiency withoutadding additional complexity at mobile nodes. Hybrid beam-forming is commonly used in millimeter-wave systems for itsimplementation efficiency. An important element of hybrid beam-forming is quantized phase shifters. In this paper, we ask iflow-resolution phase shifters suffice for beamforming-based full-duplex millimeter-wave systems. We formulate the problem ofjoint design for both self-interference suppression and downlinkbeamforming as an optimization problem, which we solve usingpenalty dual decomposition to obtain a near-optimal solution.Numerical results indicate that low-resolution phase shifters canperform close to systems that use infinite phase shifter resolution,and that even a single quantization bit outperforms half-duplextransmissions in both low and high residual self-interferencescenarios.

  • 141.
    Bagger, Reza
    et al.
    Infineon Technol. Nordic AB, Kista, Sweden.
    Andersson, P.
    Shih, C.D.
    20-Watt LDMOS Power Amplifier IC for Linear Driver Application2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper describes an LDMOS power amplifier integrated circuit for W-CDMA applications. The IC was developed with Infineon's Si LDMOS IC technology. The PA IC achieved 28.5 dB gain. When tuned for W-CDMA the IC showed 20 W PEP at IM3 = -30 dBc (two-tone), 400-MHz bandwidth (20%) around 2100 MHz, gain flatness of 0.15 dB/30 MHz, and phase flatness of 1 degree/30 MHz. The PA IC was characterized under all typical modulation formats, and is included in Infineon's product portfolio of power ICs for radio base stations.

  • 142.
    Bagger, Reza
    et al.
    Infineon Technologies Nordic AB, SE-16481 Kista, Sweden.
    Shih, C.D.
    Yu, Yinglei
    Sjostrom, J.
    Andersson, P.
    RF LDMOS Power Amplifier Integrated Circuit for W-CDMA/TD-SCDMA applications2007Ingår i: | Export | Download | Add to List | More... Proceedings of the 36th European Microwave Conference, EuMC 2006, IEEE , 2007, s. 1343-1346Konferensbidrag (Refereegranskat)
    Abstract [en]

    This article presents an LDMOS power amplifier integrated circuit for W-CDMA/TD-SCDMA applications. The IC has been developed in Infineon's Si LDMOS IC technology. The gain achieved was 27 dB. When tuned for TD-SCDMA, the IC showed 50 W PEP at IM3 = -30 dBc (two-tone). When tuned for W-CDMA, it showed 40 W PEP at IM3 = -30 dBc (two-tone) and 400 MHz bandwidth (20%) around 2100 MHz. The PA IC has been characterized under all typical modulation formats, and is included in Infineon's product portfolio of power ICs for radio base stations

  • 143.
    Baghaei-Nejad, Majid
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik- och datorsystem, ECS.
    Tenhunen, Hannu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik- och datorsystem, ECS.
    Zheng, Li-Rong
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik- och datorsystem, ECS.
    Power management and clock generator for a novel passive UWB tag2007Ingår i: 2007 International Symposium On System-On-Chip Proceedings / [ed] Nurmi, J; Takala, J; Vainio, O, 2007, s. 82-85Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we present a power management and a clock generator for a novel passive UWB tag. It can be used in many applications such as Radio Frequency Identification (RFID), and ubiquitous wireless sensing. As same as conventional RFID, the tag captures the power from the incoming RF signal, converts to DC and stores it in a relatively big capacitor. A voltage sensor and a regulator provide stable voltage for the whole circuitry during operation mode. A clock circuitry generates a low jitter and low skew clock for ultra wideband transmitter to transmit data. In such passive system the power consumption of each block should be as low as possible. On the other hand, performance degradation across process, voltage, and temperature variation (PVT) is another problematic challenge in low power and low cost circuit implementation. In this work, the power management unit including of an RF power scavenging, a voltage sensor, a low drop out regulator and a clock generator are designed and their performance across PVT variation are analyzed. The module is designed and is fabricated in CMOS 0.18 mu m technology.

  • 144.
    Bagula, Antoine B
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik- och datorsystem, ECS.
    Hybrid Routing in Next Generation IP Networks: QoS Routing Mechanisms and Network Control Strategies2006Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Communication networks have evolved from circuit-switched and hop-by-hop routed systems into hybrid data/optical networks using the Internet as a common backbone carrying narrow- and broad-band traffic offered by a multitude of access networks. This data/optical backbone is built around a multi-technology/multi-protocol routing architecture which runs the IP protocols in a collapsed IP stack where ATM and SONET/SDH have been replaced by the suite of Generalized Multiprotocol Label Switching (GMPLS) protocols. A further evolution referred to as ``IP over Photons'' or ``All IP - All Optical'' is expected where ``redundant intermediate layers'' will be eliminated to run IP directly on top of optical cross-connects (OXCs) with the expectation of achieving savings on operation expenditures (OPEX) and capital expenditures (CAPEX). ``IP over Photons'' has been stalled by the immaturity in the control and data plane technologies leading to complex and time-consuming manual network planning and configurations which require a group of ``layer experts'' to operate and maintain a hybrid data/optical network.

    By making the status of each link and node of a data/optical network visible to a common control, GMPLS protocols have opened the way for automated operation and management allowing the different layers of an IP stack to be managed by a single network operator. GMPLS protocols provide the potential to make more efficient use of the IP backbone by having network management techniques such as Traffic Engineering (TE) and Network Engineering (NE), once the preserve of telecommunications, to be reinvented and deployed to effect different Quality of Service (QoS) requirements in the IP networks. NE moves bandwidth to where the traffic is offered to the network while TE moves traffic to where the bandwidth is available to achieve QoS agreements between the current and expected traffic and the available resources. However,several issues need to be resolved before TE and NE be effectively deployed in emerging and next generation IP networks. These include (1) the identification of QoS requirements of the different network layer interfaces of the emerging and next generation IP stack (2) the mapping of these QoS requirements into QoS routing mechanisms and network control strategies and (3) the deployment of these mechanisms and strategies within and beyond an Internet domain's boundaries to maximize the engineering and economic efficiency.

    Building upon different frameworks and research fields, this thesis revisits the issue of Traffic and Network Engineering (TE and NE) to present and evaluate the performance of different QoS routing mechanisms and network control strategies when deployed at different network layer interfaces of a hybrid data/optical network where an IP over MPLS network is layered above an MP λS/Fiber infrastructure. These include mechanisms and strategies to be deployed at the IP/MPLS, MPLS/MP λS and MP λS/Fiber network layer interfaces. The main contributions of this thesis are threefold. First we propose and compare the performance of hybrid routing approaches to be deployed in IP/MPLS networks by combining connectionless routing mechanisms used by classical IGP protocols and the connection oriented routing approach borrowed from MPLS. Second, we present QoS routing mechanisms and network control strategies to be deployed at the MPLS/MP λS network layer interface with a focus on contention-aware routing and inter-layer visibility to improve multi-layer optimality and resilience. Finally, we build upon fiber transmission characteristics to propose QoS routing mechanisms where the routing in the MPLS and MP λS layers is conducted by Photonic characteristics of the fiber such as the availability of the physical link and its failure risk group probability.

  • 145.
    Bagula, Antoine B.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik- och datorsystem, ECS.
    On achieving bandwidth-aware LSP/LambdasSP multiplexing/separation in multilayer networks2006Ingår i: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008Artikel i tidskrift (Refereegranskat)
  • 146. Baldantoni, Luca
    et al.
    Lundqvist, Henrik
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    Karlsson, Gunnar
    KTH, Tidigare Institutioner                               , Mikroelektronik och informationsteknik, IMIT.
    Adaptive End-to-End FEC for Improving TCP Performance over Wireless Links2004Ingår i: 2004 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS, 2004, s. 4023-4027Konferensbidrag (Refereegranskat)
    Abstract [en]

    TCP is a reliable transport protocol that has been tuned to perform well in networks where packet losses occur mostly because of congestion. However, wireless networks are different: TCP responds both to congestion-based and error-based losses by invoking a congestion control algorithm and reducing the sending rate, resulting in degraded end-to-end performance for wireless systems. We investigate a new end-to-end approach for improving TCP performance over lossy links by using adaptive, end-to-end forward error correction (FEC) for recovering losses and consequently avoiding the TCP back-off behaviour. Of course there is a clear trade-off between the capacity consumed by FEC and the gain achieved in the overall throughput. An adaptive algorithm is needed to calculate the optimum ratio of redundancy given the state of the connection. The sender uses feedback information from the receiver to dynamically tune the FEC parameters. Through simulations we evaluate the performance of TCP with end-to-end FEC in mixed wired and wireless networks. The simulation results show in different scenarios that the throughput can be significantly improved by adding end-to-end FEC to TCP. However, compared to other improved TCP variants such as Westwood+ the performance is not improved, hence a direct modification of TCP congestion control appears to be more efficient than adding end-to-end FEC.

  • 147. Baldemair, Robert
    et al.
    Dahlman, Erik
    Fodor, Gabor
    Mildh, Gunnar
    Parkvall, Stefan
    KTH.
    Selén, Yngve
    Tullberg, Hugo
    Balachandran, Kumar
    Evolving Wireless Communications2013Ingår i: IEEE Vehicular Technology Magazine, ISSN 1556-6072, E-ISSN 1556-6080, Vol. 8, nr 1, s. 24-30Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The wireless-access networks of today will have to evolve in several ways in order to address the challenges and expectations of the future. New technology components will be introduced as part of the evolution of current wireless-access technologies, such as high-speed packet access (HSPA) and long-term evolution (LTE). However, additional components may also constitute future new wireless-access technologies, which may complement the evolved technologies. Examples of such new technology components are new ways of accessing spectrum and substantially higher frequency ranges, the introduction of massive antenna configurations, direct device-to-device communication, and ultradense deployments.

  • 148. Baliosian, Javier
    et al.
    Matusikova, Katarina
    Quinn, Karl
    Stadler, Rolf
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsnät. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Policy-based self-healing for radio access networks2008Ingår i: 2008 IEEE NETWORK OPERATIONS AND MANAGEMENT SYMPOSIUM, IEEE , 2008, s. 1007-1010Konferensbidrag (Refereegranskat)
    Abstract [en]

    Various centralized, distributed or cooperative management systems have been proposed to address the demands of wireless telecommunication networks. However, considering the size, complexity and heterogeneity that those networks will have in the future, current solutions either do not scale properly, or have no support for automation, or lack of the flexibility and simple control that operators will need for managing future networks in a cost-effective way. To address this problem, we designed Omega, a distributed and policy-based network management system that uses rich knowledge-modeling techniques to develop self-configuration capabilities. Omega also implements a novel conflict-resolution method that uses high-level goals and machine learning techniques to optimize its policy-based decisions. Using simulations, in this paper we show how Omega reduces the impact of a node crash on the overall availability of a radio access network by optimizing the lists of neighboring cells of the nodes in the vicinity.

  • 149.
    Baliosian, Javier
    et al.
    Ericsson Ireland Research Centre, Athlone, Ireland.
    Stadler, Rolf
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsnät.
    Method of Discovering Overlapping Cells2007Patent (Övrig (populärvetenskap, debatt, mm))
  • 150.
    Balkorkian, Sevag
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Hao, Zhang
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Analysis of Internal RF Interferences in Mobile2005Självständigt arbete på grundnivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats
    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.

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