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  • 1.
    Beckman, Claes
    KTH, School of Electrical Engineering and Computer Science (EECS), Centres, Center for Wireless Systems, Wireless@kth.
    Examining the performance of dul band base station antennas: What progress is being made?1996In: Integrating GSM & DCS 1800: Exploiting the business potential of, London: IIR , 1996Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    The recent growth in cellular communications has rapidly created a need for more radio channels. In order to make better use of the available frequency bands new access techniques such as TDMA (Time Division Multiple Access), FDMA (Frequency DMA) and CDMA (Code DMA) have been introduced. Still, the need for new channels is strong and new frequency bands have therefore been allocated for future wireless communication systems. These new communication systems, e.g. the European Personal Communication Network (PCN: 1710-1880MHz) and the North American Personal Communication System (PCS: 1850-1990MHz), use frequencies about twice as high as their predecessors (e.g. AMPS: 824-894MHz and GSM: 880-960MHz). However, at a time when our downtown areas already are littered with basestation antennas, operators are not keen to install more. Therefore, dual-band antennas have gained an increased interest. They would allow the operators to replace two antennas for separate frequency bands with one only, thus, reducing the windload of the towers and perhaps most importantly reducing the cost of installation.

  • 2.
    Beckman, Claes
    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.
    Lundgren, L.
    Roos, D.
    Dielectric-loaded circular ridge waveguide applicator for hyperthermia1988In: Microwave and optical technology letters (Print), ISSN 0895-2477, E-ISSN 1098-2760, Vol. 1, no 6, p. 221-223Article in journal (Refereed)
    Abstract [en]

    An applicator for intracavitary hyperthermia treatment of cancer has been designed and tested. The applicator is a section of a dielectric-loaded circular ridge waveguide closed at both ends to form a transmission cavity. An aperture in the cavity wall can produce a directed heating of a tumor growing in the wall of a body cavity such as the vagina.

  • 3.
    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).

  • 4.
    Beckman, Claes
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Nilsson, Mats
    KTH, School of Electrical Engineering and Computer Science (EECS), Communication Systems, CoS.
    Betänkande av Utredningen om radiospektrumanvändning i framtiden – Frekvenser i samhällets tjänst (SOU 2018:92)2019Other (Other (popular science, discussion, etc.))
    Abstract [sv]

    KTH, har ombetts att ge sin syn på Betänkandet enligt ovan, ert diarienummer N2019/00192/D.

    Frågeställningarna faller innanför den utbildning och forskning som bedrivs inom KTH. Skolan har under lång tid varit ett nav inom utbildning, utveckling och forskning inom radiokommunikation och även hela system för trådlösa tjänster. Ett exempel är ”Wireless@kth”, som i samarbete med industri och myndigheter bedrivit forskning inom området trådlösa system sedan 2001. Forskare inom denna konstellation har berett frågan och lämnar nedanstående yttrande.

  • 5.
    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, p. 907-908Conference 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.

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