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Pilot tone aided measurements to extend the bandwidth of radio frequency applications
University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences. KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.ORCID iD: 0000-0001-8460-6509
University of Gävle, Faculty of Engineering and Sustainable Development, Department of Electronics, Mathematics and Natural Sciences.
KTH, Skolan för elektro- och systemteknik (EES), Signalbehandling.
2016 (English)In: Measurement, ISSN 0263-2241, E-ISSN 1873-412X, Vol. 90, 534-541 p.Article in journal (Refereed) Published
Abstract [en]

A technique to extend the effective measurement bandwidth of a non-coherent vector receiver is presented. This bandwidth extension technique relies on the use of a pilot signal (known a priori), which is added on the signal of interest and is measured in a single receiver. Compared to other bandwidth extension techniques referred as stitching techniques, the proposed approach avoids error propagation in the measurement bandwidth and simultaneously enables the measurement of signals that do not contain energy in certain spectral bands.

The pilot signal is created in digital stages, which tackles to large extent the requirement of the a priori knowledge of this signal. Further, the pilot signal is designed to minimize estimation errors of the proposed technique, providing enhanced performance. It is analytically shown that the error incurred by the proposed method is always lower than the error from the measurement noise.

Measurement results show the method functionality with an error in the range of −50 dB of the signal measured. Finally, the usefulness of the proposed technique is illustrated by measuring the input and output of an amplifier with dynamic range in excess of 80 dB over 290 MHz using an 18 MHz bandwidth receiver. This measurement could not have been performed by existing stitching techniques.

Place, publisher, year, edition, pages
2016. Vol. 90, 534-541 p.
Keyword [en]
Bandwidth extension, Digitally modulated signals, Noncoherent vector receivers, Vector signal analyzer (VSA), Multisine signal
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
URN: urn:nbn:se:hig:diva-18942DOI: 10.1016/j.measurement.2016.05.005ISI: 000377389600062Scopus ID: 2-s2.0-84969632452OAI: oai:DiVA.org:hig-18942DiVA: diva2:786305
Available from: 2013-02-04 Created: 2015-02-05 Last updated: 2017-01-12Bibliographically approved
In thesis
1. Vector Measurements for Wireless Network Devices
Open this publication in new window or tab >>Vector Measurements for Wireless Network Devices
2013 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Wireless networks are an iconic technology of today’s modern era, theyare present in our daily activities as can be exemplified by cellular communications,wi-fi, bluetooth, and others. Vector measurements play an importantrole in the design, simulation, and testing of wireless networks and are usedto characterize key devices operating in the radio interface, such as amplifiers,filters, and mixers.Accurate characterization is the key for improving the capacity and efficiencyof wireless networks. As the demand for network capacity continuouslyincreases, the accuracy of vector measurements must also improve. Further,it is anticipated that such trends will continue in the years to come. Consequently,the wireless industry needs to include nonlinear behavior in theircharacterization and analysis, to assess and guaranty the operation of the devices,and to comply to the specifications from governmental regulations. Incontrast to linear behavior, nonlinear behavior presents an additional bandwidthrequirement because the signal bandwidth grows when it passes throughnonlinear devices. In this thesis, vector measurements for devices operatingin wireless networks are studied, emphasizing a synthetic approach for theinstrumentation. This approach enables the use of digital post-processing algorithms,which enhances the measurement accuracy and/or speed and canovercome hardware impairments. This thesis presents the design of a vectorialmeasurement system for wireless devices considering the aforementionedtrends and requirements. It also explores the advantages of the proposedapproach, describes its limitations, and discusses the digital signal processingalgorithms used to reach its final functionality. Finally, measurement resultsof the proposed setup are presented, analyzed and compared to those of modernindustrial instruments.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. 45 p.
Series
TRITA-EE, ISSN 1653-5146 ; 2013:004
Keyword
Vector measurements, radio frequency, synthetic instrumentation, bandwidth extension
National Category
Telecommunications
Research subject
Järnvägsgruppen - Elsystem
Identifiers
urn:nbn:se:hig:diva-18940 (URN)978-91-7501-630-6 (ISBN)
Presentation
2013-02-22, Hörsal 99131, Kungsbäcksvägen 47, Gävle, 13:00 (English)
Opponent
Supervisors
Available from: 2015-02-05 Created: 2015-02-05 Last updated: 2015-02-05Bibliographically approved
2. Digital Compensation Techniques for Transmitters in Wireless Communications Networks
Open this publication in new window or tab >>Digital Compensation Techniques for Transmitters in Wireless Communications Networks
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Since they appeared, wireless technologies have deeply transformed our society. Today, wireless internet access and other wireless applications demandincreasingly more traffic. However, the continuous traffic increase can be unbearableand requires rethinking and redesigning the wireless technologies inmany different aspects. Aiming to respond to the increasing needs of wirelesstraffic, we are witnessing a rapidly evolving wireless technology scenario.This thesis addresses various aspects of the transmitters used in wireless communications.Transmitters present several hardware (HW) impairments thatcreate distortions, polluting the radio spectrum and decreasing the achievabletraffic in the network. Digital platforms are now flexible, robust and cheapenough to enable compensation of HW impairments at the digital base-bandsignal. This has been coined as ’dirty radio’. Dirty radio is expected in future transmitters where HW impairments may arise to reduce transmitter cost or to enhance power efficiency. This thesis covers the software (SW) compensation schemes of dirty radio developed for wireless transmitters. As describedin the thesis, these schemes can be further enhanced with knowledge of thespecific signal transmission or scenarios, e.g., developing cognitive digital compensationschemes. This can be valuable in today’s rapidly evolving scenarioswhere multiple signals may co-exist, sharing the resources at the same radiofrequency (RF) front-end. In the first part, this thesis focuses on the instrumentation challenges andHWimpairments encountered at the transmitter. A synthetic instrument (SI)that performs network analysis is designed to suit the instrumentation needs.Furthermore, how to perform nonlinear network analysis using the developedinstrument is discussed. Two transmitter HW impairments are studied: themeasurement noise and the load impedance mismatch at the transmitter, asis their coupling with the state-of-the-art digital compensation techniques.These two studied impairments are inherent to measurement systems and areexpected in future wireless transmitters. In the second part, the thesis surveys the area of behavioral modeling and digital compensation techniques for wireless transmitters. Emphasis is placed on low computational complexity techniques. The low complexity is motivated by a predicted increase in the number of transmitters deployed in the network, from base stations (BS), access points and hand-held devices. A modeling methodology is developed that allows modeling transmitters to achieve both reduced computational complexity and low modeling error. Finally, the thesis discusses the emerging architectures of multi-channel transmittersand describes their digital compensation techniques. It revises the MIMOVolterra series formulation to address the general modeling problem anddrafts possible solutions to tackle its dimensionality. In the framework of multi-channel transmitters, a technique to compensate nonlinear multi-carrier satellite transponders is presented. This technique is cognitive because it uses the frequency link planning and the pulse-shaping filters of the individual carriers. This technique shows enhanced compensation ability at reduced computational complexity compared to the state-of-the-art techniques and enables the efficient operation of satellite transponders.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. xiii, 63 p.
Series
TRITA-EE, ISSN 1653-5146 ; 2015:017
Keyword
Digital compensation, MIMO, wireless communications, satellite, Volterra, Amplfiers, HW effects
National Category
Telecommunications Communication Systems
Research subject
Information and Communication Technology
Identifiers
urn:nbn:se:hig:diva-19393 (URN)978-91-7595-540-7 (ISBN)
Public defence
2015-06-15, Sal 99131, Kungsbäcksvägen 47, Gävle, 10:00 (English)
Opponent
Supervisors
Available from: 2015-05-27 Created: 2015-05-27 Last updated: 2017-01-12Bibliographically approved

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