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  • 1.
    Alasali, Mohammad
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Beckman, Claes
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    LTE MIMO Performance Measurements on Board Passenger Trains2013Conference paper (Other academic)
    Abstract [en]

    Providing passenger internet on board trains with continuous connectivity at high speeds and over large rural distances is a challenging issue. A frequently used solution to the problem is to use an on board WiFi network connected to the 3G or 4G networks deployed outside the train. In order to be able to provide the capacity and the data rates that tomorrow's business travelers are expecting it has been suggested to use a combination of MIMO and carrier aggregation in the LTE-Advance standard. In this study, we practically investigate the plausibility of using MIMO functionality in an 900 LTE system when the receive antennas are mounted at a train roof about 4m above ground and the base stations antennas are on average placed 2.3km away from the track in towers with an average height of 45m and, hence, most of the time in line of site. It is found that along our test route MIMO is in practice supported by the radio channel at around 70% of the time when the train is travelling with an average speed of 185km/h and the MIMO antennas are mounted 10.5m apart.

  • 2.
    Alasali, Mohammad
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Beckman, Claes
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    LTE MIMO performance measurements on trains2013In: 2013 7th European Conference on Antennas and Propagation (EuCAP), New York: IEEE , 2013, 2327-2330 p.Conference paper (Refereed)
    Abstract [en]

    Providing passenger internet on board trains with continuous connectivity at high speeds and over large rural distances is a challenging issue. A frequently used solution to the problem is to use an on board WiFi network connected to the 3G or 4G networks deployed outside the train. In order to be able to provide the capacity and the data rates that tomorrow's business travelers are expecting it has been suggested to use a combination of MIMO and carrier aggregation in the LTE-Advance standard. In this study, we practically investigate the plausibility of using MIMO functionality in an 900 LTE system when the receive antennas are mounted at a train roof about 4m above ground and the base stations antennas are on average placed 2.3km away from the track in towers with an average height of 45m and, hence, most of the time in line of site. It is found that along our test route MIMO is in practice supported by the radio channel at around 70% of the time when the train is travelling with an average speed of 185km/h and the MIMO antennas are mounted 10.5m apart.

  • 3.
    Alasali, Mohammad
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth. KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Beckman, Claes
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Karlsson, M.
    Providing internet to trains using MIMO in LTE networks2014In: 2014 International Conference on Connected Vehicles and Expo, ICCVE 2014 - Proceedings, Institute of Electrical and Electronics Engineers (IEEE), 2014, 810-814 p.Conference paper (Refereed)
    Abstract [en]

    Providing broadband passenger internet on board trains with continuous connectivity at high speeds and over large rural distances is a challenging issue. One solution to the problem is to use an onboard WiFi network connected to multiple 3G and 4G networks deployed outside the train and aggregate their combined capacity at the IP protocol level. In order to be able to provide the capacity and the data rates that tomorrow’s travelers are expecting, the future 4G standard (LTE-Advance) uses a combination of high order MIMO and carrier aggregation. In this study we use the Swedish company Icomera’s passenger internet system for our investigation. The system provides aggregation of multiple carrier and handover on an IP level. For about 10 years the system has in Sweden primarily been using multiple 3G communication links. However, here we present analysis and onboard measurements of a 2×2 MIMO channel to fast moving train in a live LTE 900 network. The results indicate that MIMO works surprisingly well and it is discussed that by combining 8×8 MIMO with carrier aggregation in future releases of 4G, it may be possible to bring gigabit internet connections to trains.

  • 4.
    Andersson, Daniel
    et al.
    Radarbolaget, Gävle.
    Wallin, Kjell
    Radarbolaget, Gävle.
    Javashvili, Otar
    Högskolan i Gävle, Radio Center Gävle.
    Beckman, Claes
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    M-Sequence UWB Radar for Industrial Applications2010In: Program of GigaHertz Symposium 2010, March 9-10, at Lund University, 2010Conference paper (Other academic)
    Abstract [en]

    Ultra Wideband Radar has the potential of dramatically improving the control and surveillance of industrial processes in confined areas. An example is the application of UWB radar for surveillance of furnaces for heath treatment of steel billets developed by Radarbolaget in Gävle.

    In our installation at AB Sandvik Materials Technology, we have shown that by using a non-destructive UWB Radar technique it is possible to visualize in real-time the ongoing process inside the furnace behind a 0.5 m thick ceramic wall. Since the operating temperature inside the furnace is 1200 °C, there is today no other known method capable of visualizing the process for the operator of the furnace. The system is therefore designed to sustain high temperatures and powerful electromagnetic disturbances while performing measurement with wide dynamics and high stability.

    The design of this radar is based on the idea of transmitting a continuous m-sequence and then detecting the correlated impulse response (see figure below). The wide bandwidth is a requirement for obtaining high spatial accuracy and resolution but puts further requirements on the design of the antennas and the electronics. Our results show that with this technique it is possible to determine the deformation of the steel billets inside the furnace with an accuracy of less than 5 mm. The radar system is also able to detect deformations in the furnace wall

    The m-sequence radar has many advantages over other UWB radar technologies since it e.g. does not require many analogue components. Its performance is a result of the choice of code length, sampling rate and averaging. However, the resolution is still limited by the impulse response of the analogue antenna (ringing).

    In this paper system parameters that affect the overall performance of an m-sequence radar are reviewed and means of enhancing its performance are discussed.

  • 5.
    Beckman, Claes
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Verifying 3G License Coverage Requirements2011In: Advances in Vehicular Networking Technologies / [ed] Miguel Almeida, InTech , 2011, 339-356 p.Chapter in book (Other academic)
    Abstract [en]

    In the beginning of the 21’st century, the 3rd generation mobile phone systems, 3G, were introduced all around the world. In most countries, spectrum for this technology was allocated through some kind of licensing procedure. In Europe, the prevailing approach was to allocatespectrum through auctions, a process which led to a situation where the European operators found themselves committed to pay a staggering 130Bilion Euros for their 3G licenses.However, in most European countries, the fee was not the only obligation put on thelicensee: A coverage, “roll-out” requirement was in many cases also connected to the license(Northstream, 2002). Typically, these coverage requirements required that the licenseescover a certain area at a certain point in time after that the licenses had been awarded.In order for the regulators to verify that the licensees had met the coverage requirement and,hence, complied with the regulation, a method for coverage verification was needed. Suchmethods have therefore since then been developed by several European regulators (e.g. PTS2004; ECC 2007). In this book chapter we describe some general underlying consideration for the verification of radio coverage in UMTS systems and in particular we describe the Swedishmethodology developed by the Swedish Telecom regulator Post & Telestyrelsen (PTS).

  • 6.
    Beckman, Claes
    et al.
    Center for RF-Measurement Technology, University of Gävle.
    Belkow, Elena
    Post och Telestyrelsen.
    Eklund, Lars
    Post och Telestyrelsen.
    Landmark, Urban
    Post och Telestyrelsen.
    Wirdemark, Per
    Canaima International.
    Verifying 3G License Requirements: some Preliminary Swedish Results2008In: The 68th IEEE Vehicular Technology Conference: VTC2008-Fall, IEEE , 2008, 1-4 p.Conference paper (Refereed)
    Abstract [en]

    In the year 2000, the Swedish Telecom regulator “Post&Telestyrelsen” (PTS) granted in a “beauty contest” four licenses for operation of 3G mobile networks. Through this process, the licensees committed themselves to cover 8.860.000 inhabitants of the Swedish population. In order to verify the coverage and confirm compliance with the license requirements, PTS, developed a test procedure in close collaboration with the licensees.

    The present paper gives an overview of the considerations behind the design of the test method and presents some preliminary results. Today all Swedish 3G operators comply with the licence requirement and it is concluded that a method for verifying the requirement accepted by the licensees is an important tool for successful licensing of spectrum and fulfilment of licensing obligations.

  • 7.
    Beckman, Claes
    et al.
    University of Gävle.
    Eklund, Lars
    Karlsson, Bo
    Lindmark, Björn
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Ribbenfjärd, David
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Wirdemark, Per
    Verifying 3G licence requirements when every dB is worth a billion2006In: First European Conference on Antennas & Propagation: EuCAP 2006 / [ed] H. Lacoste & L. Ouwehand, 2006, 1-4 p.Conference paper (Refereed)
    Abstract [en]

    In the year 2000, the Swedish Telecom regulator: “Post&Telestyrelsen”, PTS, granted in a “beauty contest” four licenses for operations of 3G systems. To verify the coverage and the license requirements, PTS, has developed a test procedure where the field strength of the primary Common Pilot Channel, CPICH, is measured in a drive test. Designing such a test constitutes a number of challenges mainly due to the fact that in 3G the accuracy in the measurement needs to be extremely high since even a small systematic error of ~1dB could in Sweden have the consequence that each operator would have to build an extra +1000 sites at a staggering cost of ~1billion SEK!

    The present paper gives an overview of the considerations behind the design of the test method used for verification of the 3G licence requirements in Sweden.

  • 8.
    Beckman, Claes
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Karlsson, B.
    The story of Allgon: HF, VHF, cellular and microwave antennas during allmost 60 years2013In: 2013 7th European Conference on Antennas and Propagation (EuCAP), IEEE , 2013, 3171-3173 p.Conference paper (Refereed)
    Abstract [en]

    Allgon, 'The Antenna Specialist', was a leading international design house and manufacturer of antennas for almost 60 years. The company was started in Stockholm in 1947 under the name of 'Antennspecialisten', by the Swedish engineer Torbjörn Cramner and his wife Veronica. In 1951 the company moved to Åkersberga north of Stockholm where its main facilities where located until the late 90's. During its life time the company designed and produced antennas for HF, VHF, Cellular and Microwave frequency bands, and for military, emergency, private and cellular radio systems. The company was in 2004 acquired by the US based company Powerwave but still today many of its original antenna designs are in production and many thousands of its base station antennas for mobile networks are still deployed all around the World.

  • 9.
    Beckman, Claes
    et al.
    Högskolan i Gävle.
    Klahr, Stefan
    Ett ödesval för regionen2009In: Gefle Dagblad, ISSN 1103-9302, no 6 februariArticle in journal (Other (popular science, discussion, etc.))
  • 10.
    Beckman, Claes
    et al.
    University of Gävle.
    Lindmark, Björn
    Base station antennas for mobile communications2007In: 2007 IEEE International Symposium on Antennas and Propagation, 2007Conference paper (Other academic)
    Abstract [en]

    This course gives the participants a general overview of the application, implementation and design of current and future base station antennas for mobile communications. It is aimed at microwave, RF- and antenna engineers in the wireless area, but also useful for researchers looking for relevant research topics and system engineers needing a deeper understanding of the antenna component of their system. The course explains underlying theoretical and practical implementation aspects of base station antennas in mobile communication networks of today and the future.

    The course is divided into three main parts:

    (i) System Aspects,

    (ii) BTS Antenna Design,

    (iii) Diversity and MIMO

    In the first part the fundamental parameters of a base station antenna are discussed in the context of radio network design. In particular we discuss parameters such as gain, radiation patterns, frequency bands and power handling and put them in the context of cell planning, propagation and capacity.

    In the second part a general overview of base station antenna design is given. In particular the design aspects of radiators, feed networks and reflectors are discussed. Furthermore, a general discussion of array synthesis for base station antennas is given.

    In the final part of the course we give an overview of the underlying theory of diversity and MIMO systems. In particular we discuss the requirements that these systems put on the base station antennas in order to be able to deliver the data rates expected from WiMAX and the long term evolution of 3G systems.

  • 11.
    Beckman, Claes
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Lindmark, Björn
    The evolution of base station antennas for mobile communications2007In: International Conference on Electromagnetics in Advanced Applications: ICEAA 07, IEEE conference proceedings, 2007, 85-92 p.Conference paper (Refereed)
    Abstract [en]

    This paper gives a general overview of the design of base station antennas for mobile communications. It explains underlying theoretical and practical implementation aspects in mobile communication networks of today and the future. In the first part the fundamental parameters of a base station antenna are discussed in the context of radio network design. In particular we discuss parameters such as gain, radiation patterns, frequency bands and power handling and put them in the context of cell planning, propagation and capacity. In the final parts of the paper we give an overview of the underlying theory of diversity and MIMO systems.

  • 12.
    Beckman, Claes
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Nilsson, Kristoffer
    The Technical and Economic Consequences of Protecting GSM-R in Sweden2016In: 2016 IEEE 83RD VEHICULAR TECHNOLOGY CONFERENCE (VTC SPRING), IEEE, 2016Conference paper (Refereed)
    Abstract [en]

    A number of protection criteria were implemented by the Swedish regulator PTS in order to protect the GSM-R operations in Sweden. In order to protect the GSM-R receivers from interference and blocking, two different constraints were implemented: First, a limitation of the "out-of-band" emissions from the mobile operators' existing base stations operating in the 900MHz band was implemented. Secondly, a limitation of the aggregated power received over the railroad within the operator's spectrum allocation in the 900 band was added. In this study, the background of these protection criteria is presented and their technical and economic consequences estimated. Regarding "out-of-band" emissions from base stations, four alternative protection levels have been investigated: -92, -95, -98 and -107 dBm. It is found that in order to meet these requirements, safety distances of between 280 and 1200m need to be introduced, which means that between 1500 and 2700 base stations would be needed to be taken out of service. In order to avoid blocking, the received power over the embankment from each base station within the public GSM band would also be needed to be limited. The consequences of limiting the received power levels to either -10, -23 or -40 dBm were here investigated. Given the level of blocking protection, it is found that between 1085 and 2330 base stations within the vicinity of the railway track would be affected and possibly needed to be shut down To avoid causing interference, all operators - with the exception of Hi3G - may limit their "out-of-band" emissions by installing filters on the base stations. The cost of such installations is estimated at 50 000 SEK per base station. Depending on the protection level that is applied, the estimated total cost for the mobile operators is between 67 and 113 million SEK (about 12 million Euros). In order to protect the GSM-R receivers from blocking, some 3500 locomotives would need to be equipped with additional filters at a total cost of around 130 million SEK (about 14 million Euros).

  • 13.
    Beckman, Claes
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Smith, Gregory
    Shared Networks: Making Wireless Communications Affordable2005In: IEEE wireless communications, ISSN 1536-1284, E-ISSN 1558-0687, Vol. 12, no 2, 78-85 p.Article in journal (Refereed)
    Abstract [en]

    In the wake of the substantial financial commitments incurred by European and other UMTS network operators in the form of licence fees, licensees have turned to network sharing as a means of reducing the capital requirements needed to bring 3G services to market. The reception from European regulators has been mixed, due to concerns that this inhibits competition, slow buildout, or otherwise result in reduced consumer benefits. The authors believe that the generic product life cycle model provides insights that indicate that network sharing, within an appropriately constructed regulatory framework, is not a threat to vigorous competition in the 3G industry, and in fact is one of the keys to stimulating the development of advanced, ubiquitous, affordable services.

  • 14.
    Beckman, Claes
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Smith, Gregory
    The Benefits of network Sharing2005In: Radiovetenskap och Kommunikation: RVK 2005, 2005, 147-151 p.Conference paper (Refereed)
  • 15.
    Bratu, Vlad-Ioan
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Beckman, Claes
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Antenna Tilt Load Balancing in Self-Organizing Networks2013In: International Journal of Research in Wireless Systems, ISSN 2320-3617, Vol. 2, no 1, 21-26 p.Article in journal (Other academic)
    Abstract [en]

    Base station antenna tilt is a powerful tuning parameter in traditional cellular network optimization. With theintroduction of Self-Organizing Networks (SON), this parameter may now be used also in the context of self-optimization.One envisioned scenario is load balancing (LB), where the coverage shaping properties of the antenna radiation pattern canbe used to control the cell borders. In this paper, a generalized framework for antenna tilt LB is presented and discussed. Inorder to assess the performance of antenna tilt as a tool for load balancing, simulations are performed to determine theeffect of tilt angle, vertical beamwidth and handover offset. The results show that there is a direct relation between theseparameters and the number of users that can be shifted towards neighboring cells. In conclusion, it is found that usingantennas with narrow vertical beamwidths together with small hand over offsets is an efficient way of performing loadbalancing but results also in high SIR variations.

  • 16.
    Bratu, Vlad-Ioan
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Beckman, Claes
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Base station antenna tilt for load balancing2013In: 2013 7th European Conference on Antennas and Propagation (EUCAP), New York: IEEE , 2013, 2039-2043 p.Conference paper (Refereed)
    Abstract [en]

    The coverage shaping and interference reduction ability of base station antenna tilt are important tools in cellular network optimization. Through tilt changes, the coverage area of a serving cell may also be either reduced or expanded. Therefore, antenna tilt has the potential to be used for load balancing purposes. This paper gives an overview of base station antennas performance and antenna tilt. Simulations are performed in order to determine the impact of tilt changes when used for load balancing. The results show that while antenna tilt load balancing can improve the Grade of Service (GoS) in a congested cell, it will also influence the user bit rates and total cell throughput for both the congested cell and the neighbors.

  • 17.
    Bratu, Vlad-Ioan
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Beckman, Claes
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Base Station Antenna Tilt for Load Balancing and Potential use in Self-Optimizating Networks2013Conference paper (Other academic)
    Abstract [en]

    The coverage shaping and interference reduction ability of base station antenna tilt are important tools in cellular network optimization. Through tilt changes, the coverage area of a serving cell may also be either reduced or expanded. Therefore, antenna tilt has the potential to be used for load balancing purposes. With the introduction of Self-Organizing Networks (SON) in the mobile communications, this parameter may now be used also in the context of self-optimization, to address the common situation where traffic has an uneven spatial distribution between serving cells. This work gives an overview of base station antennas and antenna tilt. Simulations are performed in order to determine the impact of tilt changes when used for load balancing. The effect of tilt angle, vertical beam width and handover offset are analyzed also. The results show that there is a direct relation between these parameters and the number of users that can be shifted towards neighboring cells. In conclusion, it is found that using antennas with narrow vertical beam widths together with small hand over offsets is an efficient way of performing load balancing but results also in high SIR. Although antenna tilt load balancing can improve the Grade of Service (GoS) in a congested cell, it will also influence the user bit rates and total cell throughput for both the congested cell and the neighbors.

  • 18. Elofsson, C.
    et al.
    Karlsson, C.
    Beckman, Claes
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    On the interference between digital terrestrial television and mobile broadband in the Swedish 800 MHz band2014In: IEEE International Symposium on Electromagnetic Compatibility, IEEE conference proceedings, 2014, 528-532 p.Conference paper (Refereed)
    Abstract [en]

    In 2011, the Swedish regulator (PTS) invited all interested parties to apply for licenses to use radio transmitters in the 790-862 MHz frequency band. The licenses are service and technology neutral but all licensees are expected to provide Mobile Broadband (MBB) services using the LTE standard. In order to protect the Digital Terrestrial Television (DTT) services provided in the adjacent bands from interference, PTS imposed a number of technical conditions on the licensees. Here, a brief overview of these technical conditions is given, and a measurement campaign in order to investigate the interference between MBB and DTT services was conducted. The measurements show that the technical requirements indeed provide the additional protection for DTT reception from the MBB downlink as envisioned by PTS. However, the measurements also indicate that MBB services may be suffering from interference from TV Channel 60 within a radius of about 5km from the DTT transmitter. One year after the rollout of MBB services in the Swedish 800MHz band, very few complaints had been received by the regulator. This may be explained with that in cases where interference with the TV reception did occur, the licensees have provided additional filters for free. Another reason may be that to date only a low number of terminals including the 800 band have yet reached the Swedish market and worse interference problems from the MBB uplink may still appear.

  • 19. Halim, Humam
    et al.
    Prasad, Sathyaveer
    Högskolan i Gävle, Ämnesavdelningen för elektronik.
    Beckman, Claes
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Evaluation of a Near Field Scanner for TRP and Radiation Pattern Measurements of GSM Mobile Phones2009In: 3rd European Conference on  Antennas and Propagation, 2009. EuCAP 2009., Berlin: EUCAP2009 , 2009, 2207-2211 p.Conference paper (Other academic)
    Abstract [en]

    In this paper a new tool for estimation of the radio performance of terminal antennas in terms of Total Radiated Power, TRP is tested and evaluated. The tool is known as Lab Express and is developed by the Canadian company EMSCAN.  The results from measurements performed with the Lab Express are compared with of the radiation patterns and total radiated power (TRP) estimates, measured with a CTIA approved Satimo SG24 chamber.

        The TRP and radiation pattern measurements are performed on 10 commercially available mobile phones at GSM 900 and GSM 1800 frequency bands. The dependency of the measured TRP on the positioning of the mobile phone on EMSCAN is also tested. Our results indicate that the TRP measured with Lab Express is well correlated with the results obtained from the Satimo SG24 chamber even though the Lab Express equipment seem to over estimate the TRP with on average about 4dB at 900MHz and about 1.3dB at 1800MHz.

  • 20.
    Händel, Peter
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Prasad, Sathyaveer
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Beckman, Claes
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Maximum likelihood estimation of reverberation chamber direct-to-scattered ratio2009In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 45, no 25, 1285-U24 p.Article in journal (Refereed)
    Abstract [en]

    The exact maximum likelihood estimator of the direct-to-scattered ratio of the Rician channel in a reverberation chamber is derived and its performance analysed. It is shown that the estimator obeys a non-central F-distribution, the mean value and variance of which are derived. For well stirred chambers, it is shown that the systematic error in the estimated ratio may be significant.

  • 21.
    Ikram, Amna
    et al.
    Högskolan i Gävle, Avdelningen för elektronik, matematik och naturvetenskap.
    Beckman, Claes
    University of Gävle.
    Irmscher, Stefan
    Laird Technologies.
    Design and Development of a Multiband Loop Antenna for Cellular Mobile Handsets2011In: IEEE International Workshop on Antenna Technology, 2011, 251-254 p.Conference paper (Refereed)
    Abstract [en]

    This paper presents the results of the design and characterization of a loop antenna for mobile cellularh andsets. Based on a typical smart phone antenna geometry, a bottom mounted off-ground meanderline loop antennah as been designed, which has the potential to cover the required bands of Long Term Evolution (LTE) US 700MHz, Global System for Mobile communications (GSM) 824-960MHz, Digital Communication System (DCS) 1710-1880 MHz, Personal Communication Services PCS 1850-1990 MHz, Universal Mobile Telecommunications System (UMTS) 1920-2170MHz and LTE EU 2500. The carrier volume of 50*10*5mm3 and ground plane of length 100mm is used. The carrier permittivity εr is 2.66 and loss tangent tanδ is 0.00629 @2.44GHz. Copper is used as a metal part of the antenna having conductivity of 5.8e7 S/m and thickness of 0.1mm. The antenna supports balanced and unbalanced modes for certain frequencies. It is highly efficient in terms of small volumetric size for a given bandwidth of operations. The antenna generates weak near field electric and magnetic fields complying with the standards for the Specific Absorption Rate (SAR) and Hearing Aid Compability (HAC). The impact of body effects on the radiation efficiency has been quantified. The measured results of the prototype are in good agreement with the simulated results.

  • 22.
    Krishna, Pothula Hari
    et al.
    Högskolan i Gävle, Ämnesavdelningen för elektronik.
    Cánovas, Victor
    Högskolan i Gävle, Ämnesavdelningen för elektronik.
    Ramachandran, Prasadh
    Högskolan i Gävle, Ämnesavdelningen för elektronik.
    Beckman, Claes
    Högskolan i Gävle, Ämnesavdelningen för elektronik.
    Multi-band PIFA for combined 3G and DVB-H Terminals: a preliminary study2007In: 2007 IEEE International Workshop on Antenna Technology: Small & Smart Antennas, Metamaterials and Applications : iWAT 2007, S²AMA : conference proceedings : Cambridge, UK, March 21-23, 2007, Piscataway, NJ: IEEE , 2007, 439-442 p.Conference paper (Refereed)
    Abstract [en]

    Based on the work by Ciais et. al, a small, efficient and low profile Planar Inverted-F antenna with multi-band operations for the use in mobile telephones has been studied. The antenna was designed using a High Frequency Structure Simulator, HFSS, built and verified. In order to increase the bandwidth of the antenna from the original design it is further optimized by frequency tuning using the shorts of different parasitic element. The resulting antenna operates over two wide bands from (710-1200) MHz and from (1750-2170) MHz, covering five cellular bands and the upper part of the UHF-band allowing it to be used in terminals combining cellular and DVB-H operations.

  • 23.
    Markendahl, Jan
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Mölleryd, Bengt G.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Mäkitalo, Östen
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Beckman, Claes
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Scenario driven requirement engineering for design and deployment of mobile communication networks2011Conference paper (Refereed)
    Abstract [en]

    The numbers of users and usage of mobile data service are increasing dramatically due to the introduction of smartphones and mobile broadband dongles. For the next decade the mobile broadband market is expected to grow and reach a level where the average data consumption per user is orders of magnitude greater than today. For the telecom industry it is a magnificent challenge to design and deploy these s high-capacity wireless networks taking into account limitations in cost, energy and radio spectrum.

     

    The objective of this paper is to highlight the need to consider a multitude of scenarios for the requirements, design and deployment of mobile broad band networks. The R&D has for many years been targeting high peak data rates enabled by improved spectral efficiency, adding more spectrum bands, aggregation of frequency bands and offloading to local wireless networks connected via public fixed phones or broadband.

    However, many of these features driving the technology development are representative for the conditions in US and Western Europe. The wireless networks also need to be designed assuming deployment in regions in the world where both the availability of spectrum as well as the penetration of fixed phones and broadband are limited.

  • 24.
    Prasad, Sathyaveer
    et al.
    University of Gävle.
    Beckman, Claes
    University of Gävle.
    Comparison of Four Different Methods to Estimate the Radiated Power from Mobile Phones2010In: Comparison of Four Different Methods to Estimate the Radiated Power from Mobile Phones, 2010, 425-428 p.Conference paper (Refereed)
    Abstract [en]

    In this paper, the radiated power is estimated for various commercially available mobile phones using the Telia Scattered Field Measurement method (TSFM), In-Network performance estimation and the EMSCAN near field scanner: "Lab-Express". The results are then compared with the radiated power measured using the Satimo Star Gate 64/24 system. Our measurement results suggest that the radiated power measured in the TSFM method correlates to a great extent both with the Star Gate System and the In-network method suggesting that the TSFM method can be used an alternative tool to in-network measurements and also can be used for standard reference measurements provided accuracy and repeatability are accounted according to the standards. However, the results from the Star Gate system were weakly correlated to the results from the Lab-Express suggesting that Lab-Express cannot replace Star Gate System for standard reference measurements but can only serve as a good tool for testing antennas during design and development phases.

  • 25.
    Prasad, Sathyaveer
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Medawar, Samer
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Beckman, Claes
    Estimation of the Rician K-factor in Reverberation Chambers for Improved Repeatability in Terminal Antenna Measurements2008In: 30th Annual Symposium of the Antenna Measurement Techniques Association (AMTA), Boston, Mass.: AMTA , 2008Conference paper (Refereed)
    Abstract [en]

    The in-network performance of the mobile phone depends highly on the terminal antennas. Their performance may reduce the coverage and the capacity of the whole network. Hence, an antenna measurement method that accurately emulates the in-network radio environment is much desired.

    The reverberation, or mode-stirred, chamber is a cavity resonator with a high Q factor used for testing the performance of terminals and terminal antennas in a controlled field environment. In order to create a homogeneous field inside the chamber, emulating an isotropic multipath environment, mode stirrers are used.

    The Rician K-factor is a statistical parameter that describes the field distribution in the chamber and is defined as the ratio of the unstirred to stirred field components in the chamber. This K-factor varies from zero to infinity. In order to be able to accurately repeat a measurement performed in a reverberation chamber it is, hence, of greatest importance to accurately determine the Rician K-factor from said measurements.

    In this paper, a statistical model for the electromagnetic fields in reverberation chamber is reviewed for a Line of Sight (LOS) environment. An Estimator of the Rician K-factor is derived and its accuracy is verified.

  • 26.
    Prasad, Sathyaveer
    et al.
    Högskolan i Gävle, Ämnesavdelningen för elektronik.
    Ramachandran, Prasadh
    Glazunov, Andres Alayon
    Beckman, Claes
    EVALUATION OF THE TELIA SCATTERED FIELD MEASUREMENT METHOD FOR ESTIMATION OF IN-NETWORK PERFORMANCE OF MOBILE TERMINAL ANTENNAS2007In: 29th Annual Symposium of the Antenna Measurement Techniques Association (AMTA 2007), St.Louis,USA: AMTA 2007 , 2007Conference paper (Other academic)
    Abstract [en]

    In this paper we present and evaluate a method for estimation of in-network performance of mobile terminal antennas developed by the Swedish telecom operator Telia. The Telia Scattered Field Measurement (TSFM) Method is intended to give a better estimate of the performance of the mobile terminal antenna as in an in-network fading scenario. The parameter measured from the TSFM method is referred to as the Scattered Field Measurement Gain, SFMG, i.e. the Mean Effective Gain, MEG, measured relative to a half wave dipole antenna. MEG includes the radiation pattern of the mobile terminal antenna as well as an estimate of polarization and directional losses that occur due to the propagation environment. In this study it is found that the TSFM method provides a good measure of the in-network performance of the mobile terminal antenna. Furthermore, it is shown that the SFMG measured with this method is found to be well correlated with the Total Radiated Power Gain, TRPG, or radiation efficiency. This suggests that the Total Radiated Power, TRP, may be a good measure of the in-network performance of mobile terminal antennas if measured with proper adjustment to the antenna and propagation channel mismatch.

  • 27.
    Ramachandran, Prasadh
    et al.
    Högskolan i Gävle, Ämnesavdelningen för elektronik.
    Bengtsson, Olof
    Högskolan i Gävle, Ämnesavdelningen för elektronik.
    Beckman, Claes
    University of Gavle.
    Impedance determination of terminal power amplifiers for optimal antenna matching using load-pull method2009In: 2009 IEEE INTERNATIONAL WORKSHOP ON ANTENNA TECHNOLOGY: , IEEE , 2009, 1-4 p.Conference paper (Refereed)
    Abstract [en]

    In this paper we present a single tuner based load-pull method for characterization of optimal antenna load impedance in mobile terminals. In the proposed load-pull set-up the mobile terminal itself is used as a source. The presented method can provide valuable data for antenna design since it determines the optimal impedance at the antenna connector/pad taken into account the full output circuitry of the mobile terminal. It reveals the modification of the power amplifier, PA, output impedance caused by the presence of saw filter, antenna switch, and transmission line possibly present between the PA and the antenna. With the presented method it is not only possible to characterize the optimum antenna impedance to present to the terminal in different bands and channels but also to reveal the impedance miss-match sensitivity for each channel.

  • 28.
    Ramachandran, Prasadh
    et al.
    Högskolan i Gävle.
    Milosavljevic, Z.
    Beckman, Claes
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Adaptive penta-band handset antenna with hand effect compensation2012In: IET Microwaves, Antennas & Propagation, ISSN 1751-8725, Vol. 6, no 1, 79-86 p.Article in journal (Refereed)
    Abstract [en]

    Theincrease in the number of cellular operating bands and theever-increasing criteria antenna size reduction has pushed the need touse switchable antenna structures. Further, the presence of a handin the close vicinity of the antenna causes deterioration inperformance. The authors present a switchable antenna technique, evaluate theeffect of the human hand on it and discuss anovel method to compensate for the mismatch. A penta-band switchableplanar inverted-F antenna covering 824–960 and 1710–2170 MHz has been usedin this study. The presence of the hand was observedto cause 2.0–6.0 dB loss in efficiency for the low band.Using the proposed extra-ground antenna switching method and the dynamicantenna matching, technique the total efficiency of the antenna canbe improved by 0.5–2.5 dB compared to the mismatched case

  • 29.
    Ramachandran, Prasadh
    et al.
    University of Gävle.
    Milosavljevic, Zlatoljub
    Beckman, Claes
    University of Gävle.
    Adaptive Matching Circuit for Compensation of Finger Effect on Handst Antennas2009In: EUCAP 2009, 2009, 801-804 p.Conference paper (Refereed)
  • 30.
    Ruiz, Alberto Camacho
    et al.
    KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Beckman, Claes
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Impact of Base Station Antenna Vertical Beam Width and Tilt on the Performance of LTE Networks2016In: 2016 IEEE ANTENNAS AND PROPAGATION SOCIETY INTERNATIONAL SYMPOSIUM, IEEE, 2016, 907-908 p.Conference paper (Refereed)
    Abstract [en]

    In this study, system level simulations are performed using two different vertical antenna radiation patterns from two real base station antennas with otherwise similar characteristics. The vertical half power beam widths of the two antennas in the investigation were 4 and 8 degrees respectively. In addition the two antennas are compared with the ideal antenna model proposed by 3GPP. The results show that the choice of vertical beam width and electrical tilt setting may improve both the coverage and capacity of up to 50% in an LTE network. However, the optimum vertical beam width and tilt differs for different network sizes and propagation environment.

  • 31. Smith, Gregory
    et al.
    Beckman, Claes
    InterBell AB.
    Shared Networks: More than making wireless communication affordable2005In: Vehicular Technology Conference, 2005: VTC 2005-Spring., 2005, 2984-2988 p.Conference paper (Refereed)
    Abstract [en]

    In the wake of the substantial financial commitments incurred by European and other UMTS network operators in the form of license fees, licensees have turned to network sharing as a means of reducing the capital requirements needed to bring 3G services to market. The reception from European regulators has been mixed, due to concerns that this inhibits competition, slow build-out, or otherwise result in reduced consumer benefits. The authors believe that the generic product life-cycle model provides insights that indicate that network sharing, within an appropriately constructed regulatory framework, is not a threat to vigorous competition in the 3G industry, and in fact, is one of the keys to stimulating the development of advanced, ubiquitous, affordable services.

  • 32.
    Tecsor, Irina
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS. KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth.
    Isaksson, Gunnar
    Luleå tekniska universitet.
    Borg, Johan
    Luleå tekniska universitet.
    Beckman, Claes
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab). KTH, School of Information and Communication Technology (ICT), Centres, Center for Wireless Systems, Wireless@kth. Luleå University of Technology, Sweden.
    Initial Investigations into the Effects of Mutual Coupling and Architecture of the EISCAT3D array2013Conference paper (Other academic)
    Abstract [en]

    To study the layers of the ionosphere and also the interactions between Earth and Sun, the EISCAT association will build a three dimensional imaging radar: EISCAT3D. The infra­structure of the radar system will include 5 sites with ~10000 antenna elements each.

    For such arrays, the electromagnetic interaction between radiating elements (coupling effects) and the influence of the ground plane cannot be neglected. In addition, for array applications requiring a large number of elements, a process called thinning is most often applied to remove elements while maintaining much of the same characteristics for the antenna. When the density of components decreases, the coupling in the array will decrease as well.

    The relative position of elements doesn’t have a great influence on the performance of main beam. It has, however, on the mutual coupling that changes the input impedance of the radiators and the characteristics of the radiation pattern. The challenge is to find a layout where radiating elements will be separated enough for them not to couple but close enough to not disturb the performance of the array antenna.

    For the purpose of analyzing the performance of the EISCAT3D array, a simulation tool has been developed in Matlab/ Mathematica. In this initial study, thinned arrays with three types of elements: isotropic, half wavelength dipoles and an antenna element designed and simulated at Luleå Technical University are investigated. The latter element was designed with the ambition to meet the rigorous requirements put on the EISCAT3D array when deployed in the Northern part of Scandinavia in order to withstand the harsh environment. The radiation pattern of the single radiator is provided by an EM simulation tool (NEC2) and

    includes the mutual coupling to identical elements. Thus, analyzing the radiation pattern of the array with Luleå elements, the mutual coupling effects are taken into consideration.

    In the simulations an attempt is made to, in a realistic manner and for different scanning angles, calculate per­formance indicators such as Directivity and Sidelobe level. When the main beam is directed towards the zenith, it was found that between the three elements analyzed, dipoles will result in the lowest directivity and the smallest side lobe level. The directivity of the array with isotropic elements and Luleå elements increases with a regular pattern with increasing number of elements. Between the three types of radiators, Luleå elements will results in the highest average side lobe level and the peak side lobe level gets better than isotropic elements when more than 60% of elements are active.

1 - 32 of 32
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