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  • 1.
    Andersen, O.
    et al.
    Ericsson AB.
    Wisell, David
    Ericsson AB.
    Keskitalo, Niclas
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Measurement of ACLR with high dynamic range2008In: IEEE MTT-S International Microwave Symposium Digest, Atlanta, GA, 2008, 273-277 p.Conference paper (Other academic)
    Abstract [en]

    In this paper a method to overcome the insufficient dynamic range of RF measurement instruments, i.e. signal generators and spectrum analyzers, for distortion measurements on feedforward and other highly linear amplifiers, is discussed. A circuit board is designed, built and verified. Its performance is found to be superior to traditional methods using filters, both from a technical performance and flexibility standpoint as well as from an economic view. ACLR measurements for WCDMA signals can be done well below -70 dBc using the produced circuit board. © 2008 IEEE.

  • 2.
    Andersen, Olav
    et al.
    Ericsson.
    Björsell, Niclas
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Keskitalo, Niclas
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    A Test-Bed Designed to Utilize Zhu’s General Sampling Theorem to Characterize Power Amplifiers2009In: Instrumentation and measurement technology conference 2009 I2MTC '09 IEEE, Singapore, 2009, 201-204 p.Conference paper (Refereed)
    Abstract [en]

    Characterizing power amplifiers require test set-ups with performance superior to the power amplifiers. A commonly used method is to use an IQ-demodulator. However, problem arises due to imperfections in the demodulator such as IQ-imbalance; an alternative method is to use a direct down converter to intermediate frequency. The drawback then is the limited bandwidth. However, the required bandwidth of the ADC does not need to be exceptional. According to Zhu’s general sampling theorem is it enough to sample the output signal at the Nyquist rate of the input. However, even though the required sampling rate is reduced the demands on the analog bandwidth remains. Unfortunately, commercially available instruments such as vector signal analyzers can not be used for this purpose since their analog bandwidth is too small. In this paper a test-bed is designed to utilize the Zhu’s general sampling theorem. The RF front-end has frequency range of 500 MHz – 2.7 GHz and a bandwidth of 1 GHz. All performance data are verified with measurements.

  • 3.
    Andersen, Olav
    et al.
    Ericsson Telecom AB, Gävle, Sweden.
    Wisell, David
    Ericsson Telecom AB, Stockholm, Sweden.
    Staenvard, Patrik
    Ericsson Telecom AB, Gävle, Sweden.
    Keskitalo, Niclas
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Extending the Bandwidth and Dynamic Range of Old RF Instruments to Meet State-of-the-Art Performance, Using a Synthetic Instrument Approach2009In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 58, no 2, 248-254 p.Article in journal (Refereed)
    Abstract [en]

    A decrease in life cycle cost is a key issue for testing mobile communication systems. The rapid development and edge technology requires high-performance instruments and state-of-the-art measurement technology. New investments are expensive, but even older generation instruments are capable of extending their bandwidth and dynamic range to meet even the latest Third-Generation Partnership Project (3GPP) cellular measurement requirements by the addition of external hardware using a synthetic instrument approach. The novelty of this paper is the high performance on the most crucial parameters, i.e., the dynamic range and bandwidth achieved by only replacing some parts of the legacy instrument. Moreover, the demonstrated direct IF synthesis has a high degree of novelty at wide modulation bandwidths. It is desired to use virtual/synthetic instruments and make the signal processing in the software independent of the hardware, i.e., software-defined measurements (SDMs). In this paper, a state-of-the-art experimental setup for signal generation and signal analysis is demonstrated. A direct IF synthesis is used to generate a wideband code-division multiple-access (WCDMA) carrier with more than 72-dB adjacent carrier leakage ratio (ACLR) up to 12 parallel carriers with more than 68-dBc ACLR over a total bandwidth of 100 MHz. The signal analysis capabilities (e.g., ACLR performance) for a WCDMA carrier is better than -70 dBc and for a continuous wave better than -85 dBc over a bandwidth of 42.5 MHz. The critical RF downconverter in the setup is carefully designed not to degrade the dynamic range performance.

  • 4.
    Andersson, Daniel
    et al.
    Radarbolaget, Gävle.
    Wallin, Kjell
    Radarbolaget, Gävle.
    Javashvili, Otar
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Beckman, Claes
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    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.
    Barbé, Kurt
    et al.
    Vrije Universiteit Brussel, ELEC.
    Van Moer, Wendy
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Lauwers, L
    Vrije Universiteit Brussel.
    Björsell, Niclas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    A Simple Nonparametric Preprocessing Technique to Correct for Nonstationary Effects in Measured Data2012In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 61, no 8, 2085-2094 p.Article in journal (Refereed)
    Abstract [en]

    The general approach for modeling systems assumes that the measured signals are (weakly) stationary, i.e., the power spectrum is time invariant. However, the stationarity assumption is violated when: 1) transient effects due to experimental conditions are dominant; 2) data are missing due to, for instance, sensor failure; or 3) the amplitude of the excitation signals smoothly varies over time due to, for instance, actuator problems. Although different methods exist to deal with each of these nonstationary effects specifically, no unified approach is available. In this paper, a new and general technique is presented to handle nonstationary effects, based on processing overlapping subrecords of the measured data. The proposed method is a simple preprocessing step where the user does not need to specify which nonstationary effect is present, nor the time interval where the nonstationary effect appears. The merits of the proposed approach are demonstrated on an operational wireless system suffering from interrupted link effects.

  • 6.
    Björsell, Niclas
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Daponte, Pasquale
    Department of Engineering, University of Sannio, Italy.
    De Vito, Luca
    Department of Engineering, University of Sannio, Italy.
    Rapuano, Sergio
    Department of Engineering, University of Sannio, Italy.
    Automatic signal recognition for a flexible spectrum management2009In: XIX IMEKO World Congress, 2009, 568-573 p.Conference paper (Refereed)
    Abstract [en]

    The paper presents the prototype of an automatic digital modulation classifier, to be used for signal recognition in frequency bands managed in a flexible way. The prototype is based on a Data Acquisition System, consisting of an Analog-to-Digital converter embedded in an evaluation board, a frame grabber and a Personal Computer. The modulation classifier is able to recognize the most used digital modulations. An experimental validation of the realized prototype in a radio environment is also provided.

  • 7.
    Björsell, Niclas
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    De Vito, Luca
    University Sannio.
    Rapuano, Sergio
    University Sannio.
    A GNU radio-based signal detector for cognitive radio systems2011In: 2011 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), New York: IEEE conference proceedings, 2011, 1045-1049 p.Conference paper (Refereed)
    Abstract [en]

    This paper deals with the hardware and software architecture of a signal detector prototype. It is able to observe a wide band and to find, in such band, the empty or occupied channels. It is intended to be used either in telecommunication devices or in spectrum monitoring instruments working in the new scenarios of telecommunications, where a flexible and dynamic spectrum management will be introduced. The signal detector has been validated on simulated and emulated signals showing high detection percentages even with low signal to noise ratios.

  • 8.
    Björsell, Niclas
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    De Vito, Luca
    Department of Engineering, University of Sannio, Benevento, Italy.
    Rapuano, Sergio
    Department of Engineering, University of Sannio, Benevento, Italy.
    A waveform digitizer-based automatic modulation classifier for a flexible spectrum management2011In: Measurement, ISSN 0263-2241, E-ISSN 1873-412X, Vol. 44, no 6, 1007-1017 p.Article in journal (Refereed)
    Abstract [en]

    The paper presents the development and validation of an automatic digital modulation classifier based on a waveform digitizer architecture. The proposed automatic digital modulation classifier can be used for signal recognition in the next generation telecommunication systems, characterized by a flexible and dynamic management of the radio spectrum. It has been implemented on a PC architecture, connected with two different types of waveform digitizers. The experimental validation has been carried out by means of actual telecommunication signals, even in presence of narrowband and wideband interference. (C) 2011 Elsevier Ltd. All rights reserved.

  • 9.
    Björsell, Niclas
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Hamid, Mohamed
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Kerttula, Jussi
    Aalto.
    Imadur, Rahman
    Ericsson AB.
    Initial Report on the tolerance of legacy systems to transmissions of secondary users based on legacy specifications2010Report (Other academic)
    Abstract [en]

    Secondary use of exclusively licensed but inefficiently used spectrum bands has been proposed as a solution to make more efficient use of spectrum resources. An important requirement for such secondary usage is to ensure that the primary services and systems performance are not degraded due to the presence of the secondary system. In this report three licensed primary systems are studied, namely digital video broadcasting, radar and aeronautical systems. In this initial report, the odelled tolerance limits for the primary users are investigated and verified by means of measurements for the case of DVB systems and literature review for the cases of Radar and Aeronautical systems. The impact of interference is evaluated as a functionof Desired to Undesired Power level (D/U) ratio for DVB systems, the pulse detection error for Aeronautical systems and the maximum interference-to-noise ratio (INR) for Radar systems. The main conclusions are that co-channel and adjacent channel interference need to be taken into account when assessing the tolerance limits for secondary systems in the TV bands. Also, non-continuous bursty-type users do not cause any higher interference compared to continuous data traffic users; thus, same tolerance limits can be used for both traffic behaviours.

     

    For aeronautical systems, spatial separation and transmit power of the secondary system determine the feasibility of secondary usage of the L-band. For other radar systems e.g. in S band and C band, the INR value, the spatial separation, the transmit power of the secondary system and the IF separation effects determine the possibilities for secondary users. For DVB systems, multiple interferers cause accumulative interference effects on the co-channels and adjacent channels, and the total amount of interference caused by multiple interferers should be kept below the desired signal level.

  • 10.
    Björsell, Niclas
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Händel, Peter
    Royal Institute of Technology, Signal Processing Lab, ACCESS Linnaeus Center.
    Jansson, Magnus
    Royal Institute of Technology,Signal Processing Lab, ACCESS Linnaeus Center.
    Medawar, Samer
    Royal Institute of Technology, Signal Processing Lab, ACCESS Linnaeus Center.
    Improved Estimate of Parametric Models for Analogue to Digital Converters by Using Weighted Integral Nonlinearity Data2010In: 17th Symposium IMEKO TC4 - Measurement of Electrical Quantities, 15th International Workshop on ADC Modelling and Testing, and 3rd Symposium IMEKO TC19: Environmental Measurements / [ed] Linus Michaeli, Jan Saliga, 2010, 597-600 p.Conference paper (Refereed)
    Abstract [en]

    Error modelling has played a major role in generating post-corrections of analogue to digital converters (ADC). Benefits by using parametric models for post-correction are that they requires less memory and that they are easier to identify for arbitrary signals. However, the parameters are estimated in two steps; firstly, the integral nonlinearity (INL) is estimated and secondly, the model parameters. In this paper we propose a method to improve the performance in the second step, by utilizing information about the statistical properties of the first step.

  • 11.
    Björsell, Niclas
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies. Royal Inst Technol, ACCESS Linnaeus Ctr, Stockholm, Sweden.
    Isaksson, Magnus
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies. Royal Inst Technol, ACCESS Linnaeus Ctr, Stockholm, Sweden.
    Händel, Peter
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. Royal Inst Technol, ACCESS Linnaeus Ctr, Stockholm, Sweden.
    Rönnow, Daniel
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Kautz-Volterra modelling of analogue-to-digital converters2010In: Computer Standards & Interfaces, ISSN 0920-5489, E-ISSN 1872-7018, Vol. 32, no 3, 126-129 p.Article in journal (Refereed)
    Abstract [en]

    In many test and measurement applications, the analogue-to-digital converter (ADC) is the limiting component. Using post-correction methods can improve the performance of the component as well as the over all measurement system. In this paper an ADC is characterised by a Kautz-Volterra (KV) model, which utilises a model-based post-correction of the ADC with general properties and a reasonable number of parameters. It is also shown that the inverse model has the same dynamic properties as the direct KV model. Results that are based on measurements on a high-speed 12-bit ADC, shows good results for a third order model.

  • 12.
    Björsell, Niclas
    et al.
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Nader, Charles
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. Signal Processing Lab, Royal Institute of Technology, Stockholm, Sweden.
    Händel, Peter
    Signal Processing Lab, Royal Institute of Technology, Stockholm, Sweden.
    Multi-tone design for out-of-band characterization of nonlinear RF modules using harmonic sampling2010In: 2010 IEEE International Instrumentation and Measurement Technology Conference, I2MTC 2010: Proceedings, Piscataway, NJ: IEEE Service Center , 2010, 620-623 p., 5488231Conference paper (Refereed)
    Abstract [en]

    In this paper we evaluate the generation of a multi-tone set for characterizing the behavior of nonlinear radio frequency (RF) modules in its out-of-band when harmonic sampling is used as digitizer. The purpose is to provide the reader with a tool to select proper frequencies and record length for a given application and test-bed. The method is based on simulations and the use of Sidon sequences. The proposed method is applicable to sparse discrete frequency multi-tones.

  • 13.
    BUCCARDO, ALDO
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    A SIGNAL DETECTOR FOR COGNITIVE RADIO SYSTEM2010Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    The communication systems are changing. Cognitive Radio is an automatic adaptative system to improve the spectrum efficiency. It has intelligence to adapt itself to the environment to improve the transmission performancies. For this system, spectrum sensing function is very important so a signal detector is necessary. In this work a signal detector has been implemented in GNU Radio environment. GNU Radio is a platform that respects the Cognitive Radio aproach. It is flexible, software defined and cheap.

  • 14.
    Chilo, José
    et al.
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Stenumgaard, Peter
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Amplitude Probability Distribution Measurement in Industrial Environments2010In: IEEE International Symposium on Electromagnetic Compatibility: Workshop & Tutorial Notes, 2010, 642-645 p.Conference paper (Other academic)
  • 15.
    Ferrer Coll, Javier
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies. KTH, KTH Center för Trådlösa System, Wireless@kth.
    RF Channel Characterization in Industrial, Hospital and Home Environments2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The rapid development of electronic components has resulted in the emergence of newmobile applications targeted at industry and hospital sectors. Moreover, a lack of availablewireless frequencies as result of the growth of wireless systems is becoming a problem.In this thesis we characterize industrial and hospital environments in order to provide theknowledge necessary to asses present and future development of critical wireless applications.Furthermore, we investigate the possibility of using TV white space by analysingthe interference from secondary to primary user in home environments.

    Some of the wireless solutions used in industries and hospitals come directly fromsystems designed for home or office, such asWLAN and Bluetooth. These systems are notprepared to handle problems associated with interference of impulsive character found inindustrial processes and electrical systems.

    Typically, industrial environments have been classified as reflective environments dueto the metallic structure present in the buildings. In this thesis, we demonstrate that althoughthis may be generally true, some locations in the industry may have special propertieswith wave propagation characteristics in the opposite direction. Stored materials canabsorb wireless signals, resulting in a coverage problem. From the measurement campaignwe are able to distinguish three main classes of indoor environments (highly reflective,medium reflective and low reflective) with different propagation characteristics.

    Improving spectrum efficiency can be a solution to the growing demand for wirelessservices and can increase a system’s robustness against interference, particularly in criticalapplications in industrial and hospital environments. One improvement in spectrum efficiencycan be for secondary consumers to reuse unassigned portions of the TV spectrum ata specific time and geographical location. This thesis studies the effect of inserting whitespace devices in the TV broadcast spectrum. Note that any new model must state the maximumpower allocated to secondary users to avoid harmful interference with the primarysignal.

    The content of this thesis is divided into three parts. The first part is the most comprehensiveand addresses electromagnetic interference and multipath characterization ofindustrial environments. In this part, we have developed a method for channel characterizationfor complex electromagnetic environments and have produced results from differentindustrial environments. The second part presents a preliminary study that characterizesthe electromagnetic interference in a hospital environment. The third part is a study ofsecondary users reusing the TV white spaces.

  • 16.
    Ferrer Coll, Javier
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Chilo, José
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Slimane, Ben
    KTH.
    Radio-Frequency Electromagnetic Characterization in Factory Infrastructures2012In: IEEE transactions on electromagnetic compatibility (Print), ISSN 0018-9375, E-ISSN 1558-187X, Vol. 54, no 3, 708-711 p.Article, review/survey (Refereed)
    Abstract [en]

    In recent years, industrial wireless applications have emerged rapidly. The use of short-range radio communication systems in factories increases the flexibility in industrial processes by reducing the use of cables. However, the technological challenges involved in wireless communication in industrial environments are not trivial; they result in disadvantages with respect to reliability and security because of electromagnetic interference. To gain an understanding of the performance limits of these wireless applications, knowing the characteristics of these environments is essential. In this approach, amplitude probability distribution and rms delay spread measurements have been used to perform electromagnetic site surveys in three factory automation infrastructures.

  • 17.
    Ferrer Coll, Javier
    et al.
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. School of Information and Communication Technology, KTH Royal Institute of Technology, Kista, Sweden.
    Choquehuanca, Juan José
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Chilo, José
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Stenumgaard, Peter
    Swedish Defence Research Agency, P.O. Box 1165, SE-58111, Sweden.
    Statistical Characterization of the Electromagnetic Environment in a Hospital2010In: 2010 Asia-Pacific Symposium on Electromagnetic Compatibility, APEMC 2010, 2010, 293-296 p., 5475847Conference paper (Refereed)
    Abstract [en]

    Thanks to advances in digital technology many hospitals are becoming populated with wireless medical applications to control life critical functions. Electromagnetic interference can cause severe performance degradations on these wireless applications. Several accidents have been reported which calls for a more thorough characterization of these interferences in areas where critical wireless applications are used. In this paper the results of electromagnetic interference measurements performed in a hospital are presented. The amplitude probability distribution (APD) and the inter arrival pulse probability distribution (PSD) are used to characterize these environments. In addition, Middleton parameters can be calculated from the measured data. This study is considered to be a first effort to characterize the 20 MHz -2500 MHz band in hospitals.

  • 18.
    Ferrer Coll, Javier
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies. KTH.
    Dolz Martin de Ojeda, Jose
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Stenumgaard, Peter
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. FOI.
    Marzal Romeu, Silvia
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Chilo, José
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Industrial Indoor Environment Characterization: Propagation Models2011In: Proceedings of EMC Europe 2011 York - 10th International Symposium on Electromagnetic Compatibility, 2011, 245-249 p.Conference paper (Refereed)
    Abstract [en]

    Results of three years' field measurements on radio propagation in industrial environments have been analyzed using four propagation models: the Saleh-Valenzuela model, the twocluster model, the indoor power delay profile model, and our more recent adjusted model. In this study, we used the results of measurements performed at a steel mill, a paper mill, and in a laboratory environment for three frequency bands (183-683 MHz, 1640-2140 MHz, and 2200-2700 MHz) and for line-of-sight and non-line-of-sight cases.

  • 19.
    Ferrer Coll, Javier
    et al.
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Karlsson, Carl
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Stenumgaard, Peter
    FOI.
    Ängskog, Per
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Chilo, José
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Ultra-Wideband Propagation Channel-Measurements and Simulations in Industrial Environments2010In: 9th International Symposium on EMC joint with 20th International Wroclaw Symposium on EMC, 2010, 615-618 p.Conference paper (Refereed)
  • 20.
    Ferrer Coll, Javier
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies. KTH, School of Information and Communication Technology, Kista, Sweden .
    Ängskog, Per
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Chilo, José
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Stenumgaard, Peter
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. FOI.
    Industrial environment characterization for future M2M applications2011In: Proc. 2011 IEEE International Symposium on Electromagnetic Compatibility, New York: IEEE conference proceedings, 2011, 960-963 p.Conference paper (Refereed)
    Abstract [en]

    Combining electronics, telecommunications, and information technology to connect devices and remote systems is perhaps the best feature of the future Machine-to-Machine (M2M) technology. Wireless communication technologies for managing future M2M applications are becoming mature, but electromagnetic interference and time dispersion in industrial environments can limit the successful functioning of these wireless systems, leading to a failure in the control of critical functions. The characterization of these environments is necessary for collecting and specifying M2M requirements. In this paper, we present the conclusions from measurements carried out in four different industrial environments during the past three years.

  • 21.
    Ferrer Coll, Javier
    et al.
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. School of Information and Communication Technology, KTH Royal Institute of Technology, Sweden.
    Ängskog, Per
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Karlsson, Carl
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Chilo, José
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Stenumgaard, Peter
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. Swedish Defence Research Agency, Sweden.
    Simulation and Measurement of Electromagnetic Radiation Absorption in a Finished-product Warehouse2010In: IEEE International Symposium on Electromagnetic Compatibility, 2010, 881-884 p., 5711396Conference paper (Refereed)
    Abstract [en]

    Several studies have characterized industrial environments as being highly reflective. In this paper, we provide the data obtained from electromagnetic field measurements performed at the warehouse of a paper mill. The data is also compared to simulated data. This data proves the existence of non-reflective and very high absorption industrial environments where wireless communication is impossible at certain frequencies. Furthermore, in such environment, radio performance cannot be improved by multiple antenna solutions such as MIMO (Multiple Input Multiple Output) since multiple reflections are effectively absorbed.

  • 22.
    Ferrer-Coll, Javier
    et al.
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Ängskog, Per
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Chilo, José
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Stenumgaard, Peter
    FOI.
    Characterisation of electromagnetic properties in iron-mine production tunnels2012In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 48, no 2, 62-63 p.Article in journal (Refereed)
    Abstract [en]

    Modern underground mines require reliable wireless communication for transmitting voice data, operating surveillance cameras, and monitoring mining equipment such as heavy vehicles. The electromagnetic characteristics of mines therefore have to be considered when determining the type of wireless technology for such critical applications. In this reported work, measurements of radio interference levels, path loss, and multipath propagation are performed in the world's now largest iron ore mine, situated in Sweden, to determine a suitable wireless technology for this mine.

  • 23.
    Ferrer-Coll, Javier
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Ängskog, Per
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Shabai, He
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Chilo, José
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Stenumgaard, Peter
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. FOI, Totalförsvarets forskningsinstitut and Linköping University.
    Analysis of wireless communications in underground tunnels for industrial use2012In: 38TH ANNUAL CONFERENCE ON IEEE INDUSTRIAL ELECTRONICS SOCIETY (IECON 2012), New York: IEEE conference proceedings, 2012, 3216-3220 p.Conference paper (Refereed)
    Abstract [en]

    Wireless communication is expected to improve the safety and the productivity in underground tunnels for industrial use. However the multiple shapes and structures of tunnels affect wireless communication characteristics in terms of signal propagation which is significantly different from terrestrial environments. This paper presents comprehensive broadband measurements and simulations of multipath propagation and path loss in two underground environments. The results can be used in the development of new communication systems in tunnels that provide industrial services.

  • 24.
    Fors, K.M.
    et al.
    Swedish Def Res Agcy, Linkoping, Sweden.
    Wiklundh, K.C.
    Swedish Def Res Agcy, Linkoping, Sweden.
    Stenumgaard, Peter
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. Swedish Def Res Agcy, Linkoping, Sweden.
    Improved impulsiveness correction factor for controlling electromagnetic interference in dynamic spectrum access applications2010In: IET Communications, ISSN 1751-8628, Vol. 4, no 4, 437-442 p.Article in journal (Refereed)
    Abstract [en]

    Initiatives to open certain frequency bands for dynamic spectrum access (DSA) are ongoing. Examples are the wireless access policy for electronic communications services and white spaces coalition. A key issue in DSA is how to measure occupancy and interference in an open frequency band to decide whether or not it can be used for a certain service. Such measurement must be easy to perform and provide a result that can be used as decision metric. An earlier proposal, based on a so-called impulsiveness correction factor, with this purpose has been shown to work properly if the interference is dominated by a single pulsed signal. In this study, the former approach is extended to the case in which the interference signal consists of a multiple of interference signals. This extension is shown as a closed expression involving only parameters that can be determined from an interference measurement.

  • 25.
    Fraile, F
    et al.
    Universidad Politécnica de Valencia.
    Nader, Charles
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Guerri, J. C.
    Universidad Politécnica de Valencia.
    Björsell, Niclas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    On the reuse of DVB-T transmitter infrastructure for DVB-T22011Conference paper (Refereed)
    Abstract [en]

    The new DVB-T2 standard was specifically designed to allow the reuse of DVB-T infrastructure if required. This paper presents measurement results that verify the correct performance of a commercial DVB Power Amplifier with DVB-T2 waveforms. Furthermore, the paper includes configuration guidelines and performance evaluation of the Tone Reservation PAPR reduction algorithm included in the DVB-T2 standard. PAPR reduction is key technology when reusing DVB-T amplifiers for DVB-T2 transmissions without penalizing amplifier efficiency.

  • 26.
    Fraz, Hamza
    et al.
    Georgia Tech..
    Björsell, Niclas
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Kenney, J. S.
    Georgia Tech..
    Sperlich, R.
    Texas Instruments.
    Prediction of Harmonic Distortion in ADCs using dynamic Integral Non-Linearity model2009In: Behavioral Modeling and Simulation Workshop, 2009. BMAS 2009. IEEE, 2009, 102-107 p.Conference paper (Refereed)
    Abstract [en]

    This paper investigates the application of dynamic, Integral Non-Linearity (INL) model of Analog-to-Digital Converters (ADC) to predict the harmonic distortion in pipelined ADCs. The device used to validate the model is Texas Instruments' ADS6129; a 12-bit, 250 MSPS1 pipelined ADC. The performance of the model is measured using single tones in the first Nyquist zone, with an amplitude ranging between −1 dBFS2 and −46 dBFS. Total Harmonic Distortion (THD) and Spurious Free Dynamic Range (SFDR) are used as metrics to compare the performance of the model to the actual ADC. The results indicate that a model for High Code Frequency (HCF) INL is essential for correct prediction of distortion for input signals with small amplitudes. The results also suggest that dynamic INL models offer an effective method to model the distortion in ADCs until Nyquist frequency only. Beyond Nyquist frequency, the non-linear effects of Track and Hold (T/H) start manifesting and the INL model can no longer account for all the distortion seen at the output of ADCs.

  • 27.
    Fritzin, Jonas
    et al.
    Linköping University.
    Jung, Ylva
    Linköping University.
    Landin, Per Niklas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Händel, Peter
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Enqvist, Martin
    Linköping University.
    Alvandpour, Atila
    Linköping University.
    Phase predistortion of a class-D outphasing RF amplifier in 90 nm CMOS2011In: IEEE Transactions on Circuits and Systems - II - Express Briefs, ISSN 1549-7747, E-ISSN 1558-3791, Vol. 58, no 10, 642-646 p.Article in journal (Refereed)
    Abstract [en]

    This brief presents a behavioral model structure and5a model-based phase-only predistortion method that are suitable for outphasing RF amplifiers. The predistortion method is based on a model of the amplifier with a constant gain factor and phase rotation for each outphasing signal, and a predistorter with phase rotation only. The method has been used for EDGE and wide-band code-division multiple-access (WCDMA) signals applied to a Class-D outphasing RF amplifier with an on-chip transformer used for power combining in 90-nm CMOS. The measured peak power at 2 GHz was +10.3 dBm with a drain efficiency and power-added efficiency of 39% and 33%, respectively. For an EDGE 8 phase-shift-keying (8-PSK) signal with a phase error of 3 degrees between the two input outphasing signals, the measured power at 400 kHz offset was −65.9 dB with predistortion, compared with −53.5 dB without predistortion. For a WCDMA signal with the same phase error between the input signals, the measured adjacent channel leakage ratio at 5-MHz offset was -50.2 dBc with predistortion, compared with -38.0 without predistortion.

  • 28.
    Gonzales Fuentes, Lee
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. Vrije Universiteit Brussel.
    Barbe, Kurt
    Vrije Universiteit Brussel.
    Van Moer, Wendy
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. Vrije Universiteit Brussel.
    Björsell, Niclas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Cognitive radios: discriminant analysis finds the free space2012In: 2012 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), New York: IEEE conference proceedings, 2012, 2242-2247 p.Conference paper (Refereed)
    Abstract [en]

    Spectrum sensing is an essential pre-processing step for cognitive radio technology. This paper presents a novel method to detect the significant spectral components in measured nonflat spectra, and to estimate the magnitude of the spectral components. Furthermore, the probability that the spectral component was incorrectly classified is available. The algorithm is able to detect the presence or absence of signals in any kind of spectrum since no prior knowledge about the measured signal is needed. Hence, this method becomes a strong basis for a high-quality operation mode of cognitive radios. Simulation results prove the advantages of the presented technique.

  • 29. Gonzales-Fuentes, L.
    et al.
    Barbé, K.
    Van Moer, Wendy
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Adaptive noise tracking for Cognitive Radios under more realistic operation conditions2014In: IEEE Instrumentation and Measurement Technology Conference, 2014, 1339-1344 p.Conference paper (Refereed)
    Abstract [en]

    Normal operation conditions of cognitive radio applications require signal processing techniques that can be executed in real time. One of the first steps is to sense the occupied or free frequency channels. Two major drawbacks in the current techniques are that they assume (i) the noise as white and (ii) the measured spectrum as time-invariant. In real world, the noise is (i) colored so it disturbs the signal unevenly and (ii) its spectrum changes over time. Hence, tracking the time-varying noise spectrum can become crucial to remove the noise contributions and enhance the estimate of the received signal. In this paper, we study an auto-regressive model to develop an adaptive noise tracking technique using a Kalman filter such that an extension of Boll's noise subtraction technique, designed for audio noise cancellation, becomes feasible when adjusted to cognitive radio scenarios. Simulation results show the performance of this technique. 

  • 30.
    Hamid, Mohamed
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    On Finding Spectrum Opportunities in Cognitive Radios: Spectrum Sensing and Geo-locations Database2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The spectacular growth in wireless services imposes scarcity in term of the available radio spectrum. A solution to overcome this scarcity is to adopt what so called cognitive radio based on dynamic spectrum access. With dynamic spectrum access, secondary (unlicensed) users can access spectrum owned by primary (licensed) users when it is temporally and/or geographically unused. This unused spectrum is termed as spectrum opportunity. Finding these spectrum opportunities related aspects are studied in this thesis where two approaches of finding spectrum opportunities, namely spectrum sensing and geo-locations databases are considered.

    In spectrum sensing arena, two topics are covered, blind spectrum sensing and sensing time and periodic sensing interval optimization. For blind spectrum sensing, a spectrum scanner based on maximum minimum eigenvalues detector and frequency domain rectangular filtering is developed. The measurements show that the proposed scanner outperforms the energy detector scanner in terms of the probability of detection. Continuing in blind spectrum sensing, a novel blind spectrum sensing technique based on discriminant analysis called spectrum discriminator has been developed in this thesis. Spectrum discriminator has been further developed to peel off multiple primary users with different transmission power from a wideband sensed spectrum. The spectrum discriminator performance is measured and compared with the maximum minimum eigenvalues detector in terms of the probability of false alarm, the probability of detection and the sensing time.

    For sensing time and periodic sensing interval optimization, a new approach that aims at maximizing the probability of right detection, the transmission efficiency and the captured opportunities is proposed and simulated. The proposed approach optimizes the sensing time and the periodic sensing interval iteratively. Additionally, the periodic sensing intervals for multiple channels are optimized to achieve as low sensing overhead and unexplored opportunities as possible for a multi channels system.

    The thesis considers radar bands and TV broadcasting bands to adopt geo-locations databases for spectrum opportunities. For radar bands, the possibility of spectrum sharing with secondary users in L, S and C bands is investigated. The simulation results show that band sharing is possible with more spectrum opportunities offered by C band than S and L band which comes as the least one. For the TV broadcasting bands, the thesis treats the power assignment for secondary users operate in Gävle area, Sweden. Furthermore, the interference that the TV transmitter would cause to the secondary users is measured in different locations in the same area.

  • 31.
    Hamid, Mohamed
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies. Communications Systems Lab (CoS), Royal Institute of Technology (KTH), Stockholm, Sweden .
    Barbe, Kurt
    Vrije Universiteit Brussel, ELEC.
    Björsell, Niclas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies. Communications Systems Lab (CoS), Royal Institute of Technology (KTH), Stockholm, Sweden .
    Van Moer, Wendy
    Vrije Universiteit Brussel.
    Spectrum sensing through spectrum discriminator and maximum minimum eigenvalue detector: a comparative study2012In: 2012 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), New York: IEEE conference proceedings, 2012, 2252-2256 p.Conference paper (Refereed)
    Abstract [en]

    In this paper we present a new spectrum sensing technique for cognitive radios based on discriminant analysis called spectrum discriminator and compare it with the maximum minimum eigenvalue detector. The common feature between those two techniques is that neither prior knowledge about the system noise level nor the primary user signal, that might occupy the band under sensing, is required. Instead the system noise level will be derived from the received signal. The main difference between both techniques is that the spectrum discriminator is a non-parametric technique while the maximum minimum eigenvalue detector is a parametric technique. The comparative study between both has been done based on two performance metrics: the probability of false alarm and the probability of detection. For the spectrum discriminator an accuracy factor called noise uncertainty is defined as the level over which the noise energy may vary. Simulations are performed for different values of noise uncertainty for the spectrum discriminator and different values for the number of received samples and smoothing factor for the maximum minimum eigenvalue detector.

  • 32.
    Hamid, Mohamed
    et al.
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Björsell, Niclas
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    A Novel Approach for Energy Detector Sensing Time and Periodic Sensing Interval Optimization in Cognitive Radios2011In: Proceedings of the 4th International Conference on Cognitive Radio and Advanced Spectrum Management, New York: ACM Press, 2011Conference paper (Refereed)
    Abstract [en]

    In this paper a new approach of optimizing the sensing time and periodic sensing interval for energy detectors has been explored. This new approach is built upon maximizing the probability of right detection, captured opportunities and transmission efficiency. The probability of right detection is defined as the probability of having no false alarm and correct detection. Optimization of the sensing time relies on maximizing the summation of the probability of right detection and the transmission efficiency while optimization of periodic sensing interval subjects to maximizing the summation of transmission efficiency and the captured opportunities. The optimum sensing time and periodic sensing interval are dependent on each other, hence, iterative approach to optimize them is applied and convergence criterion is defined. The simulations show that both converged sensing time and periodic sensing interval increase with the increase of the channel utilization factor, moreover, the probability of false alarm, the probability of detection, the probability of right detection, the transmission efficiency and the captured opportunities have been taken as the detector performance metrics and evaluated for different values of channel utilization factor and signal-to-noise ratio.

  • 33.
    Hamid, Mohamed
    et al.
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Björsell, Niclas
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Geo-location Spectrum Opportunities Database in Downlink Radar Bands for OFDM Based Cognitive Radios2011Conference paper (Refereed)
    Abstract [en]

    In this paper a model to investigate the spectrum opportunities for cognitive radio networks in three radar frequency bands L, S and C at a specific location is introduced. We consider underlay unaware spectrum sharing model. The Secondary System we assume is an OFDM based system. The followed strategy is built upon defining a specific co or adjacent channel as a spectrum opportunity if -and only if- the interference generated by the secondary system occupying that channel  into the radar system is less than the permissible interference defined by the value of Interference to Noise ratio (INR) and the radar receiver inherited noise level. The simulation results show that for the same transmission parameters C band offer more spectrum opportunities than S band which is itself offers more spectrum opportunities than L band.

  • 34.
    Hamid, Mohamed
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Björsell, Niclas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Maximum Minimum Eigenvalues Based Spectrum Scanner for Cognitive Radios2012In: 2012 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), New York: IEEE conference proceedings, 2012, 2248-2251 p.Conference paper (Refereed)
    Abstract [en]

    In this paper we introduce a technique for spectrum scanning with the maximum minimum eigenvalue detection based spectrum sensing. The fundamental problem we address in this paper is the inability of using maximum minimum eigenvalue detection with filtering in time domain where the white noise becomes coloured. The solution we propose here is based on frequency domain rectangular filtering. By frequency domain rectangular filtering we take the spectral lines inside each sub-band and throw out the rest. After doing the frequency domain rectangular filtering, we generate the corresponding time domain signal and inject it to the maximum minimum eigenvalue detector. An experimental verification has been performed and the obtained results show that the technique is implementable with a performance better than the energy detector as a reference technique in terms of the probability of detection when both technique have the same probability of false alarm.

  • 35.
    Hamid, Mohamed
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies. Royal Institute of Technology (KTH), Stockholm, Sweden .
    Björsell, Niclas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. Vrije Universiteit Brussel, Belgium .
    Mohammed, Abbas
    Blekinge Institute of Technology.
    Iterative Optimization of Energy Detector Sensing Time and Periodic Sensing Interval in Cognitive Radio Networks2013In: Self-Organization and Green Applications in Cognitive Radio Networks / [ed] Anwer Al-Dulaimi, John Cosmas, Abbas Mohammed, IGI Global, 2013, 1, 53-69 p.Chapter in book (Refereed)
    Abstract [en]

    In this chapter the authors propose a new approach for optimizing the sensing time and periodic sensing interval for energy detectors in cognitive radio networks. The optimization of the sensing time depends on maximizing the summation of the probability of right detection and transmission efficiency, while the optimization of periodic sensing interval is subject to maximizing the summation of transmission efficiency and captured opportunities. Since the optimum sensing time and periodic sensing interval are dependent on each other, an iterative approach to optimize them simultaneously is proposed and a convergence criterion is devised. In addition, the probability of detection, probability of false alarm, probability of right detection, transmission efficiency, and captured opportunities are taken as performance metrics for the detector and evaluated for various values of channel utilization factors and signal-to-noise ratios.

  • 36.
    Hamid, Mohamed
    et al.
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. KTH.
    Mohammed, Abbas
    Blekinge Institute of Technology.
    MAC Layer Spectrum Sensing in Cognitive Radio Networks2013In: Self-Organization and Green Applications in Cognitive Radio Networks / [ed] Anwer Al-Dulaimi, John Cosmas, Abbas Mohammed, IGI Global, 2013, 1, 210-230 p.Chapter in book (Refereed)
    Abstract [en]

    Efficient use of the available licensed radio spectrum is becoming increasingly difficult as the demand and usage of the radio spectrum increases. This usage of the spectrum is not uniform within the licensed band but concentrated in certain frequencies of the spectrum while other parts of the spectrum are inefficiently utilized. In cognitive radio environments, the primary users are allocated licensed frequency bands while secondary cognitive users can dynamically allocate the empty frequencies within the licensed frequency band, according to their requested quality of service specifications. In this chapter, the authors investigate and assess the performance of MAC layer sensing schemes in cognitive radio networks. Two performance metrics are used to assess the performance of the sensing schemes: the available spectrum utilization and the idle channel search delay for reactive and proactive sensing schemes. In proactive sensing, the adapted and non-adapted sensing period schemes are also assessed. Simulation results show that proactive sensing with adapted periods provides superior performance at the expense of higher computational cost performed by network nodes.

  • 37.
    Hamid, Mohamed
    et al.
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Mohammed, Abbas
    BTH.
    Yang, Zhe
    On Spectrum Sharing and Dynamic Spectrum Allocation: MAC Layer Spectrum Sensing in Cognitive Radio Networks2010Conference paper (Refereed)
    Abstract [en]

    One of the most critical issues regarding wireless networksregulation agencies is how to manage the available electromagneticradio spectrum in a way that satisfies the needs of the huge growingin wireless systems both economically and technically, especiallywith the recent crowding in the available spectrum. Hence, buildingcognitive radio systems supporting dynamic access to the availablespectrum has appeared recently as a novel solution for the wirelesssystem huge expansion. In this paper we investigate the MAC layersensing schemes in cognitive radio networks, where both reactiveand proactive sensing are considered. In proactive sensing theadapted and non-adapted sensing periods schemes are also assessed.The assessment of these sensing schemes has been held via twoperformance metrics: available spectrum utilization and idlechannel search delay. Simulation results show that with proactivesensing adapted periods we achieve the best performance but withan observable overhead computational tasks to be done by thenetwork nodes

  • 38.
    Horvath, György
    et al.
    Institutionen för kliniska vetenskaper, sektionen för onkologi, radiofysik, radiologi och urologi, Avdelningen för onkologi.
    Chilo, José
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Lindblad, Thomas
    Royal Institute of Technology, Stockholm, Sweden.
    Different volatile signals emitted by human ovarian carcinoma and healthy tissue2010In: Future Oncology, ISSN 1479-6694, E-ISSN 1744-8301, Vol. 6, no 6, 1043-1049 p.Article, review/survey (Refereed)
  • 39.
    Händel, Peter
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies. Royal Institute of Technology, Signal Processing Lab, ACCESS Linnaeus Centre, Stockholm, Sweden.
    Prasad, Sathyaveer
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies. Royal Institute of Technology, Signal Processing Lab, ACCESS Linnaeus Centre, Stockholm, Sweden.
    Beckman, Claes
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Maximum likelihood estimation of reverberation chamber direct-to-scattered ratio2009In: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 45, no 25, 1285-1286 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.

  • 40.
    Ikram, Amna
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Beckman, Claes
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    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.

  • 41.
    Javashvili, Otar
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Department of Technology and Built Environment.
    UWB Antennas for Wall Penetrating Radar Systems2009Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Basic properties and new design principles of ultra wideband Vivaldi antennas are presentedand discussed in this paper. The focus will be on the modeling of Vivaldi antenna design curves, by which it is constructed; its simulation results, realization and the measurements.

    According to the aim of this research the discussion starts with the review of the previous researches done for Vivaldi antennas. Introductory part of the report also contains the problem description for the current project and the classification of the goals to be achieved. As a theoretical review, the discussion initiates with the definitions anddescription of basic parameters of the antennas and covers a short presentation of UWBpulse-based radar system. The attention will be focused on UWB signals behavior and characterization, their propagation principles and basic troubles stands nowadays. As anapplication the wall penetrating Radar systems will be considered. The major part of thereport holds on the investigation of the design principles of Vivaldi Antenna andoptimization of the key parameters for achieving the best performance for radar. Theending part of the report shows the simulations and measurement results and theircomparisons following with conclusions/discussions.

    The report will be supportive for the antenna designers, who work for UWB systems andparticularly for Vivaldi antennas, as long as there are showing up detailed descriptions ofVivaldi antenna characteristics depending on its shape and substrate properties. The modelfor designing Vivaldi antennas, given in this project, can successfully be applied for almostall the cases used in practice nowadays.

  • 42.
    Javashvili, Otar
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Andersson, Daniel
    Radarbolaget.
    New method for design implementation of Vivaldi antennas to improve its UWB behaviour (EuCAP 2010)2010In: Proceedings of the Fourth European Conference on Antennas and Propagation: EuCAP 2010 - The 4th European Conference on Antennas and Propagation, 2010, 5505298Conference paper (Refereed)
    Abstract [en]

    The aim of this paper is to investigate the parameters of one of the UWB Sensors, called Vivaldi Antenna, and to propose the new ways how they can be improved. As a practical implementation of the sensor, the UWB radar for wall penetrating applications with impulse excitation was utilized. For wall penetration low frequency (0.3 – 8 GHz) supporting UWB signals are required. Within the scope of this project, the Vivaldi antenna parameters are improved in order to optimize the radiation bandwidth with an usable gain response along the whole operating band, including lower frequencies. It also automatically leads to the optimization of the size of the antenna. In addition, an investigation of the phase linearity and UWB behavior of the antenna was carried out.

  • 43.
    Landin, Per
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Isaksson, Magnus
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik.
    Keskitalo, Niklas
    University of Gävle, Center for RF Measurement Technologies.
    Tornblad, Olof
    Infineon Technologies.
    Sideband asymmetries in RF Power LDMOS Before and After Digital Predistortion2009Conference paper (Other academic)
    Abstract [en]

     The merging of the fields of RF engineering and signal processing has introduced concepts such as behavioral modeling and enabled digital linearization schemes for wireless devices, such as power amplifiers (PAs). Despite that this process has been going on for a number of years much work remains to be done. The links between physical behavior and mathematical models are far from well-understood as are the optimum strategies for device design. This study focus on digital predistortion properties of a one-stage PA consisting of a power transistor mounted in a test fixture. The device under test (DUT) is an Infineon PTF210451E, a 45W transistor intended for usage in the frequency bands 2010-2025 MHz and 2110-2170 MHz. The test fixture is also designed by Infineon Technologies.  The signal types used in the measurements are single and double carrier wideband code division multiple access (WCDMA) signals. The double carrier WCDMA signals have tone-spacings of 5, 10 and 15 MHz. Normal two-tone measurements are also presented. 

  • 44.
    Landin, Per Niklas
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Isaksson, Magnus
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Händel, Peter
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Parameter Extraction and Performance Evaluation Method for Increased Performance in RF Power Amplifier Behavioral Modeling2010In: International Journal of RF and Microwave Computer-Aided Engineering, ISSN 1096-4290, E-ISSN 1099-047X, Vol. 20, no 2, 200-208 p.Article in journal (Refereed)
  • 45.
    Landin, Per Niklas
    et al.
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Isaksson, Magnus
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för elektronik. University of Gävle, Center for RF Measurement Technologies.
    Keskitalo, Niclas
    University of Gävle, Center for RF Measurement Technologies.
    Tornblad, Olof
    A Study of memory effects of RF power LDMOS before and after digital predistortion2009In: Wireless and Microwave Technology Conference, 2009. WAMICON '09. IEEE 10th Annual, 2009, 1-5 p.Conference paper (Refereed)
    Abstract [en]

    Sideband asymmetries in distortion products are created due to electrical and thermal memory effects and this can be difficult to correct for in a digital predistortion algorithm. In this study, sideband asymmetries in third-order intermodulation distortion products before and after digital predistortion were investigated using 2-tone and 2-carrier WCDMA signals. The parallel Hammerstein (PH) model was used in the digital predistortion algorithm. The sign of the asymmetries before correction were found to depend on power level. Memoryless correction lead to an increase in asymmetries for some power ranges whereas using a PH model of order 13 with only one order of memory length lead to good correction over a large power range.

  • 46.
    Landin, Per Niklas
    et al.
    University of Gävle, Center for RF Measurement Technologies.
    Nader, Charles
    University of Gävle, Center for RF Measurement Technologies.
    Björsell, Niclas
    University of Gävle, Center for RF Measurement Technologies.
    Isaksson, Magnus
    University of Gävle, Center for RF Measurement Technologies.
    Wisell, David
    Ericsson AB.
    Händel, Peter
    University of Gävle, Center for RF Measurement Technologies.
    Andersen, Olav
    Ericsson AB.
    Keskitalo, Niclas
    University of Gävle, Center for RF Measurement Technologies.
    Wideband Characterization of Power Amplifiers Using Undersampling2009In: 2009 IEEE MTT-S International Microwave Symposium, Boston: IEEE MTT , 2009, 1365-1368 p.Conference paper (Refereed)
    Abstract [en]

    In this paper a radio frequency power amplifier is measured and characterized by the use of undersampling based on the generalized Zhu-Frank sampling theorem. A test system has been designed allowing the bandwidth of the stimuli signal to be 100 MHz in the characterization process. That would not be possible with any vector signal analyzer on the market. One of the more challenging problem within the proposed concept is the model validation process. Here, two different techniques for model validation are proposed, the multitone and the spectrum scan validation methods.

  • 47.
    Landin, Per Niklas
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Rönnow, Daniel
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences, Electronics.
    Odd and Odd-Even Memory Polynomial Representations2013Report (Other academic)
    Abstract [en]

    It is shown that the absolute value of a complex-valued function can be expressed as a polynomial in the square of the absolute value of the function. A series expansion is given and related to the Volterra-series. The results find application in explaining and improving the understanding of the “even” order memory polynomial models.

  • 48.
    Medawar, Samer
    et al.
    Signal Processing Laboratory, ACCESS Linnaeus Center, Royal Institute of Technology, Stockholm, Sweden.
    Händel, Peter
    Signal Processing Laboratory, ACCESS Linnaeus Center, Royal Institute of Technology, Stockholm, Sweden.
    Björsell, Niclas
    University of Gävle, Center for RF Measurement Technologies. University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
    Jansson, Magnus
    Signal Processing Laboratory, ACCESS Linnaeus Center, Royal Institute of Technology, Stockholm, Sweden.
    Input Dependent Integral Nonlinearity Modeling for Pipelined Analog-Digital Converters2010In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 59, no 10, 2609-2620 p.Article in journal (Refereed)
    Abstract [en]

    Integral nonlinearity (INL) for pipelined analog–digital converters (ADCs) operating at RF is measured and characterized. A parametric model for the INL of pipelined ADCs is proposed, and the corresponding least-squares problem is formulated and solved. The INL is modeled both with respect to the converter output code and the frequency stimuli, which is dynamic modeling. The INL model contains a static and a dynamic part. The former comprises two 1-D terms in ADC code that are a sequence of zero-centered linear segments and a polynomial term. The 2-D dynamic part consists of a set of polynomials whose parameters are dependent on the ADC input stimuli. The INL modeling methodology is applied to simulated and experimental data from a 12-bit commercial ADC running at 210 mega samples per second. It is demonstrated that the developed methodology is an efficient way to capture the INL of nowadays ADCs running at RF, and it is believed that the methodology is powerful for INL-based ADC postcorrection in wideband applications.

  • 49.
    Medawar, Samer
    et al.
    Signal Processing Lab, ACCESS Linnaeus Center, Stockholm, Sweden.
    Händel, Peter
    Signal Processing Lab, ACCESS Linnaeus Center, Stockholm, Sweden.
    Björsell, Niclas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Jansson, Magnus
    Signal Processing Lab, ACCESS Linnaeus Center, Stockholm, Sweden.
    Model order determination and segmentation of analog-digital converters integral non linearity2010In: 2010 IEEE International Instrumentation and Measurement Technology Conference, I2MTC 2010: Proceedings, 2010, 36-41 p., 5488188Conference paper (Refereed)
    Abstract [en]

    Analog-digital converter (ADC) integral nonlinearity (INL) modeling is investigated. The model is comprised of two entities: a low code frequency (LCF) component modeled by an L-order polynomial, and a static high code frequency component (HCF), modeled by P linear disjoint segments centered around zero. Both model components are functions of the ADC output code k. A methodical way of estimating the LCF polynomial order L and the set of segments (number of and their borders), is suggested. The method computes the polynomial order L and the set of segments (number and borders) that minimizes the root mean square (RMS) distance between the INL data and its model. The method is applied to measured INL sequences of a 12-bit Analog Devices pipeline ADC (AD9430).

  • 50.
    Medawar, Samer
    et al.
    Signal Processing Lab, ACCESS Linnaeus Center, Royal Institute of Technology.
    Händel, Peter
    Signal Processing Lab, ACCESS Linnaeus Center, Royal Institute of Technology.
    Björsell, Niclas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. University of Gävle, Center for RF Measurement Technologies.
    Jansson, Magnus
    Signal Processing Lab, ACCESS Linnaeus Center, Royal Institute of Technology.
    Pipelined Analog-Digital Converters Integral Nonlinearity Modeling for Post-Correction2010In: 17th Symposium IMEKO TC4 - Measurement of Electrical Quantities, 15th International Workshop on ADC Modelling and Testing, and 3rd Symposium IMEKO TC19: Environmental Measurements / [ed] Linus Michaeli, Jan Saliga, 2010, 585-590 p.Conference paper (Refereed)
    Abstract [en]

    Input-dependent integral nonlinearity (INL) model is developed for pipeline ADC post-correction. The INL model consists of a static and dynamic part. The INL model is subtracted out of the ADC digital output for compensation. Static compensation is performed by adjacent sets of gains and offsets. Each set compensates an output code k range. The frequency content of the INL dynamic component is used to design a set of filters blocks that performs ADC compensation in the time domain. The compensation scheme is applied to measured data of two 12-bit ADCs of the same type (Analog Devices AD9430). Performance improvements in terms of spurious free dynamic range (SFDR), signal-to-noise and Distortion ratio (SINAD), intermodulation istortion (IMD) are obtained.

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