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  • 7451.
    Zetterberg, Kristina
    Linköpings universitet, Institutionen för systemteknik.
    High-Speed Downlink Shared Channel in Unlicensed Frequency Bands2004Självständigt arbete på grundnivå (yrkesexamen)Studentuppsats
    Abstract [en]

    In the standardized air interface for third generation mobile communication systems, WCDMA release 5, a concept called High Speed Downlink Packet Access (HSDPA) is introduced. HSDPA enables faster transmissions from base stations to mobile users by using a shared, high-capacity channel called the High-Speed Downlink Shared Channel (HS-DSCH) that is designed for best effort services. The HS-DSCH is developed for usage in the frequency band licensed for third generation communication systems. As the use of licensed frequency bands is costly it may be interesting to make use of the unlicensed frequency bands at 2.4 GHz and 5 GHz with higher interference and stricter regulations. Using HS- DSCH in unlicensed frequency bands would lead to smaller costs and a new kind of usage of the HS-DSCH.

    In order to transmit in unlicensed frequency bands, some requirements set up by the public authorities must be followed. This means that the maximum transmit power used by the HS-DSCH must be decreased and, on the 5 GHz frequency band, that features to avoid disturbing radar systems have to be implemented. The HS- DSCH has a bandwidth of 5 MHz. To use the available frequency spectra more efficiently, multiple carriers could be used.

    Wireless Local Area Networks (WLANs) are the most common way to transfer data in unlicensed frequency bands today. Assessments and simulations of WLAN and the HS-DSCH in unlicensed frequency bands show that WLAN can provide higher bitrates than the HS-DSCH for low loads. HS-DSCH can however provide a larger coverage per base station, and is more bandwidth effective than WLAN. Using a larger bandwidth is necessary for HS-DSCH to compete with WLAN, which uses a bandwidth approximately four times as large as the HS-DSCH bandwidth. The usage of the HS-DSCH in unlicensed frequency bands also has the advantage that the services provided by the third generation communication systems can be accessed easily.

  • 7452.
    Zetterlund, Olof
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Optimization of Vehicle Powertrain Model Complexity for Different Driving Tasks2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This master thesis has examined how the understanding of different driving tasks can be used to develop a suitable powertrain model to be used in the Sim III simulator at VTI. Studies performed in the simulator have been statistically analyzed using parameters commonly used to describe driving patterns in drive cycles. It has been shown that the studies can be divided into three driving tasks: "High constant velocity", "High velocity with evasive maneuver", and "Mixed driving". Furthermore, a powertrain model from a former master thesis has been further developed. The new model utilizes a 3D torque map that takes engine speed, accelerator pedal position and gear as input. Using measurements, from the chassis dynamometers laboratory at LiU, that resembles the derived driving tasks, it has been shown that the performance of the new model has significantly increased for high velocity driving and during maximum acceleration. However, when using the clutch at low speeds and gears the model still performs poorly and needs further development.

  • 7453.
    Zetterqvist, Carin
    Linköpings universitet, Institutionen för systemteknik.
    Powertrain modelling and control algorithms for traction control2007Självständigt arbete på grundnivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats
    Abstract [sv]

    För att ett fordon ska kunna bromsa, accelerera och svänga är friktion mellan däcken och vägen ett måste. Vid för mycket gaspådrag under en acceleration kan det hända att hjulen förlorar fäste och börjar spinna loss, något som leder till både försämrad kontroll över fordonet och att däcken slits ut i förtid. Traction controlsystemet förhindrar hjulen från att spinna loss och försöker maximera friktionen.

    Målet med detta examensarbete är att utvärdera olika reglerprinciper samt att undersöka olika möjligheter för att reglera friktionen mellan däck och väg. Det är ett svårt reglerproblem, dels på grund av dess olinjäritet, dels på grund av det faktum att friktionen är en okänd parameter.

    För att kunna undersöka olika reglermöjligheter har en modell över hjuldynamiken och en modell över drivlinan tagits fram i Matlabs simuleringsprogram Simulink. Därutöver har tre regulatorer designats: en fuzzy-regulator, en fuzzy-P-regulator och en PI-regulator. Regulatorerna utvärderades i tre tester som bland annat testade deras robusthet.

    Fuzzy-regulatorn och fuzzy-P-regulatorn lyckades reglera systemet bra. PI-regulatorn gjorde däremot inte ett tillfredsställande jobb, mest på grund av dess behov av ett börvärde.

  • 7454.
    Zhang, Dai
    Linköpings universitet, Institutionen för systemteknik.
    Design and Evaluation of an Ultra-Low Power Successive Approximation ADC2009Självständigt arbete på avancerad nivå (masterexamen), 30 poäng / 45 hpStudentuppsats
    Abstract [en]

    Analog-to-digital converters (ADC) targeted for use in medical implant devices serve an important role as the interface between analog signal and digital processing system. Usually, low power consumption is required for a long battery lifetime. In such application which requires low power consumption and moderate speed and resolution, one of the most prevalently used ADC architectures is the successive approximation register (SAR) ADC.This thesis presents a design of an ultra-low power 9-bit SAR ADC in 0.13μm CMOS technology. Based on a literature review of SAR ADC design, the proposed SAR ADC combines a capacitive DAC with S/H circuit, uses a binary-weighted capacitor array for the DAC and utilizes a dynamic latch comparator. Evaluation results show that at a supply voltage of 1.2V and an output rate of 1kS/s, the SAR ADC performs a total power consumption of 103nW and a signal-to-noise-and-distortion ratio of 54.4dB. Proper performance is achieved down to a supply voltage of 0.45V, with a power consumption of 16nW.

  • 7455.
    Zhang, Dai
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter. Linköpings universitet, Tekniska högskolan.
    Ultra-Low-Power Analog-to-Digital Converters for Medical Applications2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Biomedical systems are commonly attached to or implanted into human bodies, and powered by harvested energy or small batteries. In these systems, analog-to-digital converters (ADCs) are key components as the interface between the analog world and the digital domain. Conversion of the low frequency bioelectric signals does not require high speed, but ultralow- power operation. This combined with the required conversion accuracy makes the design of such ADCs a major challenge. Among prevalent ADC architectures, the successiveapproximation-register (SAR) ADC exhibits significantly high energy efficiency due to its good trade-offs among power consumption, conversion accuracy, and design complexity. This thesis examines the physical limitations and investigates the design methodologies and circuit techniques for low-speed and ultra-low-power SAR ADCs.

    The power consumption of SAR ADC is analyzed and its lower bounds are formulated. At low resolution, power is bounded by minimum feature sizes; while at medium to high resolution, power is bounded by thermal noise and capacitor mismatch. In order to relax the mismatch requirement on the capacitor sizing while still ensuring enough linearity for high resolution, a bottom-up weight calibration technique is further proposed. It utilizes redundancy generated by a non-binary-weighted capacitive network, and measures the actual weights of more significant capacitors using less significant capacitors.

    Three SAR ADCs have been implemented. The first ADC, fabricated in a 0.13μm CMOS process, achieves 9.1ENOB with 53-nW power consumption at 1kS/s. The main key to achieve the ultra-low-power operation turns out to be the maximal simplicity in the ADC architecture and low transistor count. In addition, a dual-supply voltage scheme allows the SAR digital logic to operate at 0.4V, reducing the overall power consumption of the ADC by 15% without any loss in performance. Based on the understanding from the first ADC and motivated by the predicted power bounds, the second ADC, a single-supply 9.1-ENOB SAR ADC in 65nm CMOS process has been further fabricated. It achieves a substantial (94%) improvement in power consumption with 3-nW total power at 1kS/s and 0.7V. Following the same concept of imposing maximal simplicity in the ADC architecture and taking advantage of the smaller feature size, the ultra-low-power consumption is achieved by a matched splitarray capacitive DAC, a bottom-plate full-range input-sampling scheme, a latch-based SAR control logic, and a multi-VT design approach. The third ADC fabricated in 65nm CMOS process targets at a higher resolution of 14b and a wider bandwidth of 5KHz. It achieves 12.5ENOB  with 1.98-μW power consumption at 0.8V and 10kS/s. To achieve the high resolution, the ADC implements a uniform-geometry non-binary-weighted capacitive DAC and employs a secondary-bit approach to dynamically shift decision levels for error correction. Moreover, a comparator with bias control utilizes the redundancy to reduce the power consumption.

    Delarbeten
    1. A 53-nW 9.1-ENOB 1-kS/s SAR ADC in 0.13-μm CMOS for Medical Implant Devices
    Öppna denna publikation i ny flik eller fönster >>A 53-nW 9.1-ENOB 1-kS/s SAR ADC in 0.13-μm CMOS for Medical Implant Devices
    2012 (Engelska)Ingår i: IEEE Journal of Solid-State Circuits, ISSN 0018-9200, E-ISSN 1558-173X, Vol. 47, nr 7, s. 1585-1593Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    This paper describes an ultra-low power SAR ADC for medical implant devices. To achieve the nano-watt range power consumption, an ultra-low power design strategy has been utilized, imposing maximum simplicity on the ADC architecture, low transistor count and matched capacitive DAC with a switching scheme which results in full-range sampling without switch boot-strapping and extra reset voltage. Furthermore, a dual-supply voltage scheme allows the SAR logic to operate at 0.4 V, reducing the overall power consumption of the ADC by 15% without any loss in performance. The ADC was fabricated in 0.13-mu m CMOS. In dual-supply mode (1.0 V for analog and 0.4 V for digital), the ADC consumes 53 nW at a sampling rate of 1 kS/s and achieves the ENOB of 9.1 bits. The leakage power constitutes 25% of the 53-nW total power.

    Ort, förlag, år, upplaga, sidor
    Institute of Electrical and Electronics Engineers (IEEE), 2012
    Nyckelord
    ADC, analog-to-digital conversion, leakage power consumption, low-power electronics, medical implant devices, successive approximation
    Nationell ämneskategori
    Teknik och teknologier
    Identifikatorer
    urn:nbn:se:liu:diva-80792 (URN)10.1109/JSSC.2012.2191209 (DOI)000306913500008 ()
    Tillgänglig från: 2012-08-30 Skapad: 2012-08-30 Senast uppdaterad: 2019-09-05Bibliografiskt granskad
    2. Analysis and Calibration of Nonbinary-Weighted Capacitive DAC for High-Resolution SAR ADCs
    Öppna denna publikation i ny flik eller fönster >>Analysis and Calibration of Nonbinary-Weighted Capacitive DAC for High-Resolution SAR ADCs
    2014 (Engelska)Ingår i: IEEE Transactions on Circuits and Systems - II - Express Briefs, ISSN 1549-7747, E-ISSN 1558-3791, Vol. 61, nr 9, s. 666-670Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    This brief analyzes the effect of capacitor variation on the design of high-resolution nonbinary-weighted successive-approximation-register analog-to-digital converters in terms of radix, conversion steps, and accuracy. Moreover, the limitation caused by the one-side redundancy of the nonbinary-weighted network is addressed and a corresponding solution with a mathematical derivation is provided. In order to relax the mismatch requirement on the capacitor sizing while still ensuring enough linearity, a bottom-up weight calibration technique accounting for noise and offset errors is proposed, and its effectiveness is demonstrated. This calibration approach can be easily incorporated into a charge-redistribution converter without modifying its main architecture and conversion sequence.

    Ort, förlag, år, upplaga, sidor
    IEEE, 2014
    Nyckelord
    Capacitor variation; digital error correction; nonbinary weighted; redundancy; successive approximation; successive approximation register (SAR) analog-to-digital converters (ADCs); weight calibration
    Nationell ämneskategori
    Elektroteknik och elektronik
    Identifikatorer
    urn:nbn:se:liu:diva-110385 (URN)10.1109/TCSII.2014.2331111 (DOI)000341985600006 ()
    Tillgänglig från: 2014-09-10 Skapad: 2014-09-10 Senast uppdaterad: 2019-09-05Bibliografiskt granskad
    3. A 3-nW 9.1-ENOB SAR ADC at 0.7 V and 1 kS/s
    Öppna denna publikation i ny flik eller fönster >>A 3-nW 9.1-ENOB SAR ADC at 0.7 V and 1 kS/s
    2012 (Engelska)Ingår i: ESSCIRC, 2012, Institute of Electrical and Electronics Engineers , 2012, s. 369-372Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    This paper presents a 10-bit SAR ADC in 65 nm CMOS for medical implant applications. The ADC consumes 3-nW power and achieves 9.1 ENOB at 1 kS/s. The ultra-low-power consumption is achieved by using an ADC architecture with maximal simplicity, a small split-array capacitive DAC, a bottom-plate sampling approach reducing charge injection error and allowing full-range input sampling without extra voltage sources, and a latch-based SAR control logic resulting in reduced power and low transistor count. Furthermore, a multi-Vt circuit design approach allows the ADC to meet the target performance with a single supply voltage of 0.7 V. The ADC achieves a FOM of 5.5 fJ/conversion-step. The INL and DNL errors are 0.61 LSB and 0.55 LSB, respectively.

    Ort, förlag, år, upplaga, sidor
    Institute of Electrical and Electronics Engineers, 2012
    Serie
    IEEEESSCIRC Proceedings, ISSN 1930-8833
    Nationell ämneskategori
    Elektroteknik och elektronik
    Identifikatorer
    urn:nbn:se:liu:diva-86346 (URN)10.1109/ESSCIRC.2012.6341331 (DOI)978-1-4673-2211-9 (ISBN)978-1-4673-2212-6 (ISBN)
    Konferens
    IEEE European Solid-State Circuits Conference (ESSCIRC 2012), 17-21 September 2012, Bordeaux, France
    Tillgänglig från: 2012-12-13 Skapad: 2012-12-13 Senast uppdaterad: 2019-09-05
    4. Power Consumption Bounds for SAR ADCs
    Öppna denna publikation i ny flik eller fönster >>Power Consumption Bounds for SAR ADCs
    2011 (Engelska)Ingår i: European Conference on Circuit Theory and Design (ECCTD), Linköping, Sweden: IEEE conference proceedings, 2011, s. 556-559Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    Power consumption is an important limitation to analog-to-digital converters. The objective of this paper is to estimate a lower bound to the power consumption of successive approximation analog-to-digital converters. This is an extension of our previous work which was limited to pipelined and flash architectures. We find that the power consumption in our case is bounded by capacitor mismatch or thermal noise at high resolution and by digital switching power at low resolution. We also evaluate our methods and the estimated lower bound is compatible with experimental data.

    Ort, förlag, år, upplaga, sidor
    Linköping, Sweden: IEEE conference proceedings, 2011
    Nationell ämneskategori
    Elektroteknik och elektronik
    Identifikatorer
    urn:nbn:se:liu:diva-73030 (URN)10.1109/ECCTD.2011.6043594 (DOI)978-1-4577-0617-2 (ISBN)978-1-4577-0616-5 (ISBN)
    Konferens
    20th European Conference on Circuit Theory and Design, Linköping, 29-31 Aug. 2011
    Tillgänglig från: 2011-12-14 Skapad: 2011-12-14 Senast uppdaterad: 2019-09-05Bibliografiskt granskad
    5. Design of CMOS sampling switch for ultra-low power ADCs in biomedical applications
    Öppna denna publikation i ny flik eller fönster >>Design of CMOS sampling switch for ultra-low power ADCs in biomedical applications
    2010 (Engelska)Ingår i: NORCHIP 2014, Tampere: IEEE , 2010, s. 1-4Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    This paper deals with the design of CMOS sampling switch for ultra-low power analog-to-digital converters (ADC) in biomedical applications. General switch design constraints are analyzed, among which the voltage droop due to the subthreshold leakage current constitutes the major error source for low-speed sampling circuits. Based on the analyses, a CMOS sampling switch with leakage-reduction has been designed for a 10-bit 1-kS/s successive approximation (SA) ADC in a standard 130 nm CMOS process. Post-layout simulation shows that the ADC with the proposed switch offers an effective number of bits (ENOB) of 9.5 while consuming only 64 nW.

    Ort, förlag, år, upplaga, sidor
    Tampere: IEEE, 2010
    Nyckelord
    CMOS integrated circuits, analogue-digital conversion, biomedical electronics, switches
    Nationell ämneskategori
    Elektroteknik och elektronik
    Identifikatorer
    urn:nbn:se:liu:diva-65477 (URN)10.1109/NORCHIP.2010.5669444 (DOI)978-1-4244-8971-8 (ISBN)978-1-4244-8972-5 (ISBN)
    Konferens
    The 32nd Norchip Conference 27-28 October 2014, Tampere, Finland
    Tillgänglig från: 2011-02-08 Skapad: 2011-02-08 Senast uppdaterad: 2019-09-05Bibliografiskt granskad
  • 7456.
    Zhang, Dai
    et al.
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska fakulteten. Catena Wireless Elect AB, Sweden.
    Alvandpour, Atila
    Linköpings universitet, Institutionen för systemteknik, Elektroniska Kretsar och System. Linköpings universitet, Tekniska fakulteten.
    A 12.5-ENOB 10-kS/s Redundant SAR ADC in 65-nm CMOS2016Ingår i: IEEE Transactions on Circuits and Systems - II - Express Briefs, ISSN 1549-7747, E-ISSN 1558-3791, Vol. 63, nr 3, s. 244-248Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This brief describes a 14-b 10-kS/s successive approximation register analog-to-digital converter (ADC) for biomedical applications. In order to achieve enhanced linearity, a uniform-geometry nonbinary-weighted capacitive digital-to-analog converter is implemented. In addition, a secondary-bit approach to dynamically shift decision levels for error correction is employed. To reduce the power consumption, the ADC also features a power-optimized comparator with bias control. Prototyped in a 65-nm CMOS process, the ADC consumes 1.98 mu W and provides an effective number of bit (ENOB) of 12.5 b at 0.8 V while occupying an active area of 0.28 mm(2).

  • 7457.
    Zhang, Dai
    et al.
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter.
    Alvandpour, Atila
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter.
    A 3-nW 9.1-ENOB SAR ADC at 0.7 V and 1 kS/s2013Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    This paper presents a 10-bit SAR ADC in 65 nm CMOS for medical implant applications. The ADC consumes 3-nW power and achieves 9.1 ENOB at 1 kS/s. The ultra-low-power consumption is achieved by using an ADC architecture with maximal simplicity, a small split-array capacitive DAC, a bottom-plate sampling approach reducing charge injection error and allowing full-range input sampling without extra voltage sources, and a latch-based SAR control logic resulting in reduced power and low transistor count. Furthermore, a multi-Vt circuit design approach allows the ADC to meet the target performance with a single supply voltage of 0.7 V. The ADC achieves a FOM of 5.5 fJ/conversion-step. The INL and DNL errors are 0.61 LSB and 0.55 LSB, respectively.

  • 7458.
    Zhang, Dai
    et al.
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter. Linköpings universitet, Tekniska högskolan.
    Alvandpour, Atila
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter. Linköpings universitet, Tekniska högskolan.
    A 3-nW 9.1-ENOB SAR ADC at 0.7 V and 1 kS/s2012Ingår i: ESSCIRC, 2012, Institute of Electrical and Electronics Engineers , 2012, s. 369-372Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a 10-bit SAR ADC in 65 nm CMOS for medical implant applications. The ADC consumes 3-nW power and achieves 9.1 ENOB at 1 kS/s. The ultra-low-power consumption is achieved by using an ADC architecture with maximal simplicity, a small split-array capacitive DAC, a bottom-plate sampling approach reducing charge injection error and allowing full-range input sampling without extra voltage sources, and a latch-based SAR control logic resulting in reduced power and low transistor count. Furthermore, a multi-Vt circuit design approach allows the ADC to meet the target performance with a single supply voltage of 0.7 V. The ADC achieves a FOM of 5.5 fJ/conversion-step. The INL and DNL errors are 0.61 LSB and 0.55 LSB, respectively.

  • 7459.
    Zhang, Dai
    et al.
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter. Linköpings universitet, Tekniska högskolan.
    Alvandpour, Atila
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter. Linköpings universitet, Tekniska högskolan.
    Analysis and Calibration of Nonbinary-Weighted Capacitive DAC for High-Resolution SAR ADCs2014Ingår i: IEEE Transactions on Circuits and Systems - II - Express Briefs, ISSN 1549-7747, E-ISSN 1558-3791, Vol. 61, nr 9, s. 666-670Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This brief analyzes the effect of capacitor variation on the design of high-resolution nonbinary-weighted successive-approximation-register analog-to-digital converters in terms of radix, conversion steps, and accuracy. Moreover, the limitation caused by the one-side redundancy of the nonbinary-weighted network is addressed and a corresponding solution with a mathematical derivation is provided. In order to relax the mismatch requirement on the capacitor sizing while still ensuring enough linearity, a bottom-up weight calibration technique accounting for noise and offset errors is proposed, and its effectiveness is demonstrated. This calibration approach can be easily incorporated into a charge-redistribution converter without modifying its main architecture and conversion sequence.

  • 7460.
    Zhang, Dai
    et al.
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter. Linköpings universitet, Tekniska högskolan.
    Bhide, Ameya
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter. Linköpings universitet, Tekniska högskolan.
    Alvandpour, Atila
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter. Linköpings universitet, Tekniska högskolan.
    A 53-nW 9.12-ENOB 1-kS/s SAR ADC in 0.13-um CMOS for medical implant devices2011Ingår i: Proceedings of the IEEE European Solid-State Circuits Conference (ESSCIRC), Helsinki, Finland: IEEE Solid-State Circuits Society, 2011, s. 467-470Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper describes an ultra-low-power SAR ADC in 0.13-um CMOS technology for medical implant devices. It utilizes an ultra-low-power design strategy, imposing maximum simplicity in ADC architecture, low transistor count, low-voltage low-leakage circuit techniques, and matched capacitive DAC with a switching scheme which results in full-range sampling without switch bootstrapping and extra reset voltage. Furthermore, a dual-supply scheme allows the SAR logic to operate at 400mV. The ADC has been fabricated in 0.13-um CMOS. In 1.0-V single-supply mode, the ADC consumes 65nW at a sampling rate of 1kS/s, while in dual-supply mode (1.0V for analog and 0.4V for digital) it consumes 53nW (18% reduction) and achieves the same ENOB of 9.12. 24% of the 53-nW total power is due to leakage. To the authors' best knowledge, this is the lowest reported power consumption of a 10-bit ADC for such sampling rates.

  • 7461.
    Zhang, Dai
    et al.
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter. Linköpings universitet, Tekniska högskolan.
    Bhide, Ameya
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter. Linköpings universitet, Tekniska högskolan.
    Alvandpour, Atila
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter. Linköpings universitet, Tekniska högskolan.
    Design of CMOS sampling switch for ultra-low power ADCs in biomedical applications2010Ingår i: NORCHIP 2014, Tampere: IEEE , 2010, s. 1-4Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper deals with the design of CMOS sampling switch for ultra-low power analog-to-digital converters (ADC) in biomedical applications. General switch design constraints are analyzed, among which the voltage droop due to the subthreshold leakage current constitutes the major error source for low-speed sampling circuits. Based on the analyses, a CMOS sampling switch with leakage-reduction has been designed for a 10-bit 1-kS/s successive approximation (SA) ADC in a standard 130 nm CMOS process. Post-layout simulation shows that the ADC with the proposed switch offers an effective number of bits (ENOB) of 9.5 while consuming only 64 nW.

  • 7462.
    Zhang, Dai
    et al.
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter. Linköpings universitet, Tekniska högskolan.
    Svensson, Christer
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter. Linköpings universitet, Tekniska högskolan.
    Alvandpour, Atila
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter. Linköpings universitet, Tekniska högskolan.
    Power Analysis of Charge-Redistribution SAR ADCs2011Ingår i: Swedish System-on-Chip Conference (SSOCC), Varberg, Sweden: IEEE Solid-State Circuits Society, 2011Konferensbidrag (Övrigt vetenskapligt)
  • 7463.
    Zhang, Dai
    et al.
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter. Linköpings universitet, Tekniska högskolan.
    Svensson, Christer
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter. Linköpings universitet, Tekniska högskolan.
    Alvandpour, Atila
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter. Linköpings universitet, Tekniska högskolan.
    Power Consumption Bounds for SAR ADCs2011Ingår i: European Conference on Circuit Theory and Design (ECCTD), Linköping, Sweden: IEEE conference proceedings, 2011, s. 556-559Konferensbidrag (Refereegranskat)
    Abstract [en]

    Power consumption is an important limitation to analog-to-digital converters. The objective of this paper is to estimate a lower bound to the power consumption of successive approximation analog-to-digital converters. This is an extension of our previous work which was limited to pipelined and flash architectures. We find that the power consumption in our case is bounded by capacitor mismatch or thermal noise at high resolution and by digital switching power at low resolution. We also evaluate our methods and the estimated lower bound is compatible with experimental data.

  • 7464.
    Zhang, Jiayi
    et al.
    Beijing Jiaotong University, Peoples R China.
    Dai, Linglong
    Tsinghua University, Peoples R China.
    Zhang, Xinlin
    Chalmers, Sweden.
    Björnson, Emil
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Wang, Zhaocheng
    Tsinghua University, Peoples R China.
    Achievable Rate of Rician Large-Scale MIMO Channels With Transceiver Hardware Impairments2016Ingår i: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 65, nr 10, s. 8800-8806Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Transceiver hardware impairments (e.g., phase noise, inphase/quadrature-phase imbalance, amplifier nonlinearities, and quantization errors) have obvious degradation effects on the performance of wireless communications. While prior works have improved our knowledge of the influence of hardware impairments of single-user multiple-input multiple-output ( MIMO) systems over Rayleigh fading channels, an analysis encompassing the Rician fading channel is not yet available. In this paper, we pursue a detailed analysis of regular and large-scale (LS) MIMO systems over Rician fading channels by deriving new closed-form expressions for the achievable rate to provide several important insights for practical system design. More specifically, for regular MIMO systems with hardware impairments, there is always a finite achievable rate ceiling, which is irrespective of the transmit power and fading conditions. For LS-MIMO systems, it is interesting to find that the achievable rate loss depends on the Rician K-factor, which reveals that the favorable propagation in LS-MIMO systems can remove the influence of hardware impairments. However, we show that the nonideal LS-MIMO system can still achieve high spectral efficiency due to its huge degrees of freedom.

  • 7465.
    Zhang, Jiayi
    et al.
    Beijing Jiaotong Univ, Peoples R China; Southeast Univ, Peoples R China.
    Wei, Yinghua
    Beijing Jiaotong Univ, Peoples R China.
    Björnson, Emil
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Han, Yu
    Southeast Univ, Peoples R China.
    Jin, Shi
    Southeast Univ, Peoples R China.
    Performance Analysis and Power Control of Cell-Free Massive MIMO Systems with Hardware Impairments2018Ingår i: IEEE Access, E-ISSN 2169-3536, Vol. 6, s. 55302-55314Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    As an interesting network architecture for future wireless communication systems, cell-free (CF) massive multiple-input multiple-output (MIMO) distributes an excess number of access points (APs) with single or multiple antennas to cooperatively communicate with several user equipments (UEs). To realize CF massive MIMO in production, hardware impairments become a crucial problem since cheaper and low-quality antennas are needed to ensure economic and energy feasibility. In this paper, we propose a framework for performance analysis in the CF massive MIMO with classical hardware distortion models. For both uplink and downlink, closed-form spectral and energy efficiency expressions are derived, respectively. Based on these results, we provide significant insights into the practical impact of hardware impairments on CF massive MIMO. For example, the impact of hardware distortion at the APs asymptotically vanishes. Furthermore, in order to ensure uniformly good service to the users, we propose a max-min power control algorithm to maximize the minimum UE rate. Via analytical and numerical results, we prove that CF massive MIMO can tolerate hardware impairments without performance reduction.

  • 7466.
    Zhang, Jiayi
    et al.
    Beijing Jiaotong Univ, Peoples R China.
    Wei, Yinghua
    Beijing Jiaotong Univ, Peoples R China.
    Björnson, Emil
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Han, Yu
    Southeast Univ, Peoples R China.
    Li, Xu
    Beijing Jiaotong Univ, Peoples R China.
    Spectral and Energy Efficiency of Cell-Free Massive MIMO Systems with Hardware Impairments2017Ingår i: 2017 9TH INTERNATIONAL CONFERENCE ON WIRELESS COMMUNICATIONS AND SIGNAL PROCESSING (WCSP), IEEE , 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    Cell-free massive multiple-input multiple-output (MIMO), with a large number of distributed access points (APs) that jointly serve the user equipments (UEs), is a promising network architecture for future wireless communications. To reduce the cost and power consumption of such systems, it is important to utilize low-quality transceiver hardware at the APs. However, the impact of hardware impairments on cell-free massive MIMO has thus far not been studied. In this paper, we take a first look at this important topic by utilizing well-established models of hardware distortion and deriving new closed-form expressions for the spectral and energy efficiency. These expressions provide important insights into the practical impact of hardware impairments and also how to efficiently deploy cell-free systems. Furthermore, a novel hardware-quality scaling law is presented. It proves that the impact of hardware impairments at the APs vanish as the number of APs grows. Numerical results validate that cell-free massive MIMO systems are inherently resilient to hardware impairments.

  • 7467.
    Zhang, Jiayi
    et al.
    Beijing Jiaotong Univ, Peoples R China.
    Xue, Xipeng
    Beijing Jiaotong Univ, Peoples R China.
    Björnson, Emil
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Ai, Bo
    Beijing Jiaotong Univ, Peoples R China.
    Jin, Shi
    Southeast Univ, Peoples R China.
    Spectral Efficiency of Multipair Massive MIMO Two-Way Relaying With Hardware Impairments2018Ingår i: IEEE Wireless Communications Letters, ISSN 2162-2337, E-ISSN 2162-2345, Vol. 7, nr 1, s. 14-17Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We consider a multipair massive multiple-input multiple-output (MIMO) two-way relaying system, where multiple pairs of single-antenna devices exchange data with the help of a relay employing a large number of antennas N. The relay consists of low-cost components that suffer from hardware impairments. A large-scale approximation of the spectral efficiency with maximum ratio processing is derived in closed form, and the approximation is tight as N -amp;gt; infinity. It is revealed that for a fixed hardware quality, the impact of the hardware impairments vanishes asymptotically when N grows large. Moreover, the impact of the impairments may even vanish when the hardware quality is gradually decreased with N, if a scaling law is satisfied. Finally, numerical results validate that multipair massive MIMO two-way relaying systems are robust to hardware impairments at the relay.

  • 7468.
    Zhang, Jingcheng
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Huynh, Allan
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Huss, Patrik
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Ye, Qin-zhong
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Gong, Shaofang
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    A Web-based Remote Indoor Climate Control System Based on Wireless Sensor Network2013Ingår i: International Journal of Sensors and Sensor Networks, ISSN 2329-1796, Vol. 1, nr 3, s. 32-40Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents the design and implementation of a web-based wireless indoor climate control system. The user interface of the system is implemented as a web service. People can login to the website and remotely control the indoor climate of different locations. A wireless sensor network is deployed in each location to execute control commands. A gateway is implemented to synchronize the information between the wireless sensor network and the web service. The gateway software also includes scheduling function and different control algorithms to improve the control result. Additionally, the system security and availability are highly considered in this system. The gateway software implements a warning function which sends warning messages when emergency happens. Finally, the whole wireless control system architecture is modularly designed. It is easy to add different control applications or different control algorithms into the system.

  • 7469.
    Zhang, Jingcheng
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Huynh, Allan
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Ye, Qin-zhong
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Gong, Shaofang
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    A Communication Reliability Enhancement Framework for Wireless Sensor Network Using the ZigBee Protocol2011Ingår i: Sensors & Transducers Journal, ISSN 2306-8515, E-ISSN 1726-5479, Vol. 135, nr 12, s. 42-56Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents the methods for the ZigBee network reliability enhancement and the battery life time optimization. The paper begins with the introduction of the common communication problems due to the broken links between sensor module and message relay, or between different relays. Extra message hand shake mechanisms are added to solve different problem mentioned at the beginning. Finally, a general purpose reliability enhancement component is developed as a state machine which can be work together with ZigBee protocol to enhance ZigBee network communication reliability. Moreover, the battery life time of the sensor module during link broken is considerably increased after the enhancement.

  • 7470.
    Zhang, Jingcheng
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Ye, Qin-zhong
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Huynh, Allan
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Gong, Shaofang
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Design and Implementation of a Truly Battery-Driven ZigBee Wireless Sensor Network2013Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    As defined by the ZigBee standard, a router should be mains-powered in order to maintain the mesh feature of the ZigBee network. This study presents a method which allows the ZigBee router goes into sleep mode periodically and keeps the same mesh feature during the ZigBee communications. In this study, the standard ZigBee communication is separated into two synchronized clusters. The first cluster includes the communication between end devices and the associated router. The sensor message report time of different end devices are scheduled by the router in different collision-free time slots within a predefined time interval. The second cluster includes the mesh communication between routers and the concentrator. All routers are synchronized so that they wake up at the same time to maintain the mesh feature. In order to maximize the router battery lifetime, algorithms are developed so that the concentrator communicates with routers according to the network routing records. Additionally, in order to recover the broken communication, special logics are implemented in routers and end device so that they can rejoin the wireless sensor network with low power consumption. Finally, a battery lifetime model is presented which can be utilized to calculate battery lifetime of the ZigBee router under different network configurations.

  • 7471.
    Zhang, Kai
    et al.
    Jinan Univ, Peoples R China.
    Qu, Ting
    Jinan Univ, Peoples R China.
    Zhou, Dajian
    Guangdong Univ Technol, Peoples R China.
    Thurer, Matthias
    Jinan Univ, Peoples R China.
    Liu, Yang
    Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, Industriell miljöteknik. Linköpings universitet, Tekniska fakulteten. Jinan Univ, Peoples R China.
    Nie, Duxian
    South China Agr Univ, Peoples R China.
    Li, Congdong
    Jinan Univ, Peoples R China.
    Huang, George Q.
    Jinan Univ, Peoples R China; Univ Hong Kong, Peoples R China.
    IoT-enabled dynamic lean control mechanism for typical production systems2019Ingår i: Journal of Ambient Intelligence and Humanized Computing, ISSN 1868-5137, E-ISSN 1868-5145, Vol. 10, nr 3, s. 1009-1023Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The emergence and subsequent popularization of lean has been one of the most significant developments in the history of operations management. However, there is a lack of systematic theory on the control framework underlying lean production. It is therefore difficult to conduct more in-depth research on Lean theory, specifically in the context of emerging technologies as smart manufacturing or Industry 4.0. In this study, process control theory is used to re-define several major lean methods and tools. Then a Lean-Oriented Optimum-State Control Theory (L-OSCT) is proposed that integrates these lean methods and tools into optimum-state control theory. On the level of method and mechanism, we adopt a recently emerged synchronization approach to obtain global-wide leanness of a large-scale system. L-OSCT provides dynamic process control in industrial networking systems. At last, a case study in a large-size paint making company in China is used to validate the effectiveness of the approach.

  • 7472.
    Zhang, Liang
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik.
    Network Capacity, Coverage Estimation and Frequency Planning of 3GPP Long Term Evolution2010Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The recent increase of mobile data usage and emergence of new applications such as Online Gaming, mobile TV, Web 2.0, Streaming Contents have greatly motivated the 3rd Generation Partnership Project (3GPP) to work on the Long Term Evolution (LTE). The LTE is the latest standard in the mobile network technology tree. It inherits and develops the GSM/EDGE and UMTS/HSPA network technologies and is a step toward the 4th generation (4G) of radio technologies designed to optimize the capacity and speed of 3G mobile communication networks. In this thesis, the LTE system capacity and coverage are investigated and a model is proposed on the base of the Release 8 of 3GPP LTE standards. After that, the frequency planning of LTE is also studied. The results cover the interference limited coverage calculation, the traffic capacity calculation and radio frequency assignment. The implementation is achieved on the WRAP software platform for the LTE Radio Planning.

  • 7473.
    Zhang, Lili
    Linköpings universitet, Institutionen för systemteknik.
    A study of IEEE 802.16a OFDM-PHY Baseband2005Självständigt arbete på grundnivå (yrkesexamen)Studentuppsats
    Abstract [en]

    This thesis work carries out a study of IEEE 802.16 standards and mainly concentrates on the 802.16a OFDM PHY layer. A Simulink model based on 802.16a OFDM PHY baseband is built for simulation and performance evaluation. All mandatory blocks in the 802.16a OFDM-PHY specification are included: Randomization, FEC,adaptive modulation, and IFFT/FFT. A multipath Rayleigh fading channel is implemented and frequency domain channel estimation is selected for this model. Perfect synchronization is assumed.

  • 7474.
    Zhang, Nayuan
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska högskolan.
    Investigation and design of a wideband microwave VCO2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In this thesis, some most popular technologies for both resonator and active device were presented and compared. Two MMIC VCOs were selected to design on InGaP HBT and push push configuration with different topologies, namely balanced Colpitts and balanced Clapp. Optimization factors which give significant contribution to lower phase noise were investigated, such as Q factor, current density, bias circuitry, feedback capacitor ratio and etc. The optimum simulation results were obtained in the end of this work, which have the lowest phase noise such as -119.6 ~ -122.2 dBc/Hz (f0) with more than 16% tuning range and -108.7 ~ -111.2 dBc/Hz (f0) with 10% tuning range at 100 kHz offset frequency, respectively. The results were also analyzed by the formula of FOMT, which were -191.01 dBc/Hz and -182.48 dBc/Hz, respectively. The phase noise performance can reach the state of the art level and indicate potential applications.

  • 7475.
    Zhang, Qinghua
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Wavelet Network: The Radial Structure and an Efficient Initialization Procedure1992Rapport (Övrigt vetenskapligt)
  • 7476.
    Zhang, Qinghua
    et al.
    IRISA, France.
    Iouditski, Anatoli
    INRIA, France.
    Ljung, Lennart
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Identification of Wiener Systems with Monotonous Nonlinearity2007Rapport (Övrigt vetenskapligt)
    Abstract [en]

    A Wiener system is composed of a linear dynamic subsystem followed by a static nonlinearity. It is well known in the literature that the identification of the linear subsystem of a Wiener system can be separated from that of the output nonlinearity, if the input signal is Gaussian distributed. In order to deal with the non Gaussian input case, two new algorithms are proposed in this paper for direct identification of the linear subsystem, regardless of any parametrization of the output nonlinearity. The essential assumption required in this paper is the strict monotonousness of the output nonlinearity.

  • 7477.
    Zhang, Qinghua
    et al.
    Inria IFSTTAR, France.
    Ljung, Lennart
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    From structurally independent local LTI models to LPV model*2017Ingår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 84, s. 232-235Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The local approach to linear parameter varying (LPV) system identification consists in interpolating individually estimated local linear time invariant (LTI) models corresponding to fixed values of the scheduling variable. It is shown in this paper that, without any global structural assumption of the considered LPV system, individually estimated local state-space LTI models do not contain sufficient information for determining similarity transformations making them coherent. It is possible to estimate these similarity transformations from input-output data under appropriate excitation conditions. (C) 2017 Published by Elsevier Ltd.

  • 7478.
    Zhang, Qinghua
    et al.
    IRISA-INRIA, France.
    Ljung, Lennart
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Multiple Steps Prediction with Nonlinear ARX Models2004Ingår i: Proceedings of the 2004 IFAC Symposium on Nonlinear Control Systems, 2004Konferensbidrag (Refereegranskat)
    Abstract [en]

    Abstract NLARX (NonLinear AutoRegressive with eXogenous inputs) models are frequently used in black-box nonlinear system identication. Though it is easy to make one step ahead prediction with such models, multiple steps prediction is far from trivial. The main difficulty is that in general there is no easy way to compute the mathematical expectation of an output conditioned by past measurements. An optimal solution would require intensive numerical computations related to nonlinear filltering. The purpose of this paper is to investigate simple non optimal prediction methods. It is shown that cautions must be paid when using such methods, since their prediction behaviors may be radically different, depending on some detailed choice.

  • 7479.
    Zhang, Qinghua
    et al.
    IRISA-INRIA, France.
    Ljung, Lennart
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Multiple Steps Prediction with Nonlinear ARX Models2007Rapport (Övrigt vetenskapligt)
    Abstract [en]

    NLARX (NonLinear AutoRegressive with eXogenous inputs) models are frequently used in black-box nonlinear system identication. Though it is easy to make one step ahead prediction with such models, multiple steps prediction is far from trivial. The main difficulty is that in general there is no easy way to compute the mathematical expectation of an output conditioned by past measurements. An optimal solution would require intensive numerical computations related to nonlinear filltering. The purpose of this paper is to investigate simple non optimal prediction methods. It is shown that cautions must be paid when using such methods, since their prediction behaviors may be radically different, depending on some detailed choice.

  • 7480.
    Zhang, Qinghua
    et al.
    Institut de Recherche en Informatique et Systèmes Aléatoires, France.
    Wang, Jiandong
    Peking University, China.
    Ljung, Lennart
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Optimality Analysis of the Two-Stage Algorithm for Hammerstein System Identification2009Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The Two-Stage Algorithm (TSA) has been extensively used and adapted for the identification of Hammerstein systems. It is essentially based on a particular formulation of Hammerstein systems in the form of bilinearly parameterized linear regressions. This paper has been motivated by a somewhat contradictory fact: though the optimality of the TSA has been established by Bai in 1998 only in the case of some special weighting matrices, the unweighted TSA is usually used in practice. It is shown in this paper that the unweighted TSA indeed gives the optimal solution of the weighted nonlinear least-squares problem formulated with a particular weighting matrix. This provides a theoretical justification of the unweighted TSA, and leads to a generalization of the obtained result to the case of colored noise with noise whitening. Numerical examples of identification of Hammerstein systems are presented to validate the theoretical analysis.

  • 7481. Zhang, X.
    et al.
    Fu, Z.
    Yu, B.
    Fowler, Scott
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Joint Distortion Estimation and Layer Selection of Unequal Error Protection for SVC Video Transmission over FSO Networks2019Ingår i: 2019 IEEE 21st International Conference on High Performance Computing and Communications; IEEE 17th International Conference on Smart City; IEEE 5th International Conference on Data Science and Systems (HPCC/SmartCity/DSS), 2019, s. 726-733Konferensbidrag (Refereegranskat)
    Abstract [en]

    To meet the needs of high throughput, low delay and high resolution video services, the free space optical network (FSO) has recently received increasing attention due to its large bandwidth and high transmission rate. However, atmospheric turbulence is a major challenge, which can lead to severe BER performance degradation or even make the link ineffective. To mitigate the significant degradation of the video streaming quality on FSO networks, in this paper, an unequal error protection (UEP) scheme for scalable video coding is designed to minimize the video distortion. By adaptively choosing the number of video layers and the redundancy rate of the channel coding, unequal error protection of Scalable video coding is achieved. In addition, to solve the optimization model, a heuristic-based fast algorithm is proposed. A large number of simulation experiments in an NS3 network simulator show that the proposed scheme offers significantly higher quality in the reconstructed video sequences.

  • 7482.
    Zhang, Xingjun
    et al.
    Xi An Jiao Tong University, Peoples R China.
    Zhu, Guofeng
    Xi An Jiao Tong University, Peoples R China.
    Wang, Endong
    Inspur Beijing Elect Informat Ind Co Ltd, Peoples R China.
    Fowler, Scott
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska fakulteten.
    Dong, Xiaoshe
    Xi An Jiao Tong University, Peoples R China.
    Data De-Duplication with Adaptive Chunking and Accelerated Modification Identifying2016Ingår i: Computing and informatics, ISSN 1335-9150, Vol. 35, nr 3, s. 586-614Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The data de-duplication system not only pursues the high de-duplication rate, which refers to the aggregate reduction in storage requirements gained from de-duplication, but also the de-duplication speed. To solve the problem of random parameter-setting brought by Content Defined Chunking (CDC), a self-adaptive data chunking algorithm is proposed. The algorithm improves the de-duplication rate by conducting pre-processing de-duplication to the samples of the classified files and then selecting the appropriate algorithm parameters. Meanwhile, FastCDC, a kind of content-based fast data chunking algorithm, is adopted to solve the problem of low de-duplication speed of CDC. By introducing de-duplication factor and acceleration factor, FastCDC can significantly boost de-duplication speed while not sacrificing the de -duplication rate through adjusting these two parameters. The experimental results demonstrate that our proposed method can improve the de -duplication rate by about 5 %, while FastCDC can obtain the increase of de -duplication speed by 50 % to 200 % only at the expense of less than 3 % de duplication rate loss.

  • 7483.
    Zhang, Xinlin
    et al.
    Chalmers, Sweden.
    Matthaiou, Michail
    Chalmers, Sweden; Queens University of Belfast, North Ireland.
    Coldrey, Mikael
    Ericsson AB, Sweden.
    Björnson, Emil
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Energy Efficiency Optimization in Hardware-Constrained Large-Scale MIMO Systems2014Ingår i: 2014 11TH INTERNATIONAL SYMPOSIUM ON WIRELESS COMMUNICATIONS SYSTEMS (ISWCS), IEEE , 2014, s. 992-996Konferensbidrag (Refereegranskat)
    Abstract [en]

    Large-scale multiple-input multiple-output (MIMO) communication systems can bring substantial improvement in spectral efficiency and/or energy efficiency, due to the excessive degrees-of-freedom and huge array gain. However, large-scale MINI is expected to deploy lower-cost radio frequency (RF) components, which are particularly prone to hardware impairments. Unfortunately, compensation schemes are not able to remove the impact of hardware impairments completely, such that a certain amount of residual impairments always exists. In this paper, we investigate the impact of residual transmit RF impairments (RTRI) on the spectral and energy efficiency of training-based point-to-point large-scale MIMO systems, and seek to determine the optimal training length and number of antennas which maximize the energy efficiency. We derive deterministic equivalents of the signal-to-noise-and-interference ratio (SINR) with zero-forcing (ZF) receivers, as well as the corresponding spectral and energy efficiency, which are shown to be accurate even for small number of antennas. Through an iterative sequential optimization, we find that the optimal training length of systems with RTRI can be smaller compared to ideal hardware systems in the moderate SNR regime, while larger in the high SNR regime. Moreover, it is observed that RTRI can significantly decrease the optimal number of transmit and receive antennas.

  • 7484.
    Zhang, Xinlin
    et al.
    Chalmers, Sweden.
    Matthaiou, Michail
    Chalmers, Sweden; Queens University of Belfast, North Ireland.
    Coldrey, Mikael
    Ericsson Research Gothenburg, Sweden.
    Björnson, Emil
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Impact of Residual Transmit RF Impairments on Training-Based MIMO Systems2015Ingår i: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 63, nr 8, s. 2899-2911Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Radio-frequency (RF) impairments, which intimately exist in wireless communication systems, can severely limit the performance of multiple-input-multiple-output (MIMO) systems. Although we can resort to compensation schemes to mitigate some of these impairments, a certain amount of residual impairments always persists. In this paper, we consider a training-based point-to-point MIMO system with residual transmit RF impairments (RTRI) using spatial multiplexing transmission. Specifically, we derive a new linear channel estimator for the proposed model, and show that RTRI create an estimation error floor in the high signal-to-noise ratio (SNR) regime. Moreover, we derive closed-form expressions for the signal-to-noise-plus-interference ratio (SINR) distributions, along with analytical expressions for the ergodic achievable rates of zero-forcing, maximum ratio combining, and minimum mean-squared error receivers, respectively. In addition, we optimize the ergodic achievable rates with respect to the training sequence length and demonstrate that finite dimensional systems with RTRI generally require more training at high SNRs than those with ideal hardware. Finally, we extend our analysis to large-scale MIMO configurations, and derive deterministic equivalents of the ergodic achievable rates. It is shown that, by deploying large receive antenna arrays, the extra training requirements due to RTRI can be eliminated. In fact, with a sufficiently large number of receive antennas, systems with RTRI may even need less training than systems with ideal hardware.

  • 7485.
    Zhang, Yingfeng
    et al.
    Key Laboratory of Contemporary Design and Integrated Manufacturing Technology, Ministry of Education, Northwestern Polytechnical University, Shaanx, China / Department of Industrial Engineering, Northwestern Polytechnical University, Xi’an, China.
    Zhang, Geng
    Key Laboratory of Contemporary Design and Integrated Manufacturing Technology, Ministry of Education, Northwestern Polytechnical University, Shaanx, China.
    Liu, Yang
    Department of Production, University of Vaasa, Vaasa, Finland.
    Hu, Di
    Key Laboratory of Contemporary Design and Integrated Manufacturing Technology, Ministry of Education, Northwestern Polytechnical University, Shaanx, China.
    Research on services encapsulation and virtualization access model of machine for cloud manufacturing2015Ingår i: Journal of Intelligent Manufacturing, ISSN 0956-5515, E-ISSN 1572-8145, s. 1-15Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Considering the new requirements of the services encapsulation and virtualization access of manufacturing resources for cloud manufacturing (CMfg), this paper presents a services encapsulation and virtualization access model for manufacturing machine by combining the Internet of Things techniques and cloud computing. Based on this model, some key enabling technologies, such as configuration of sensors, active sensing of real-time manufacturing information, services encapsulation, registration and publishing method are designed. By implementing the proposed services encapsulation and virtualization access model to manufacturing machine, the capability of the machine could be actively perceived, the production process is transparent and can be timely visited, and the virtualized machine could be accessed to CMfg platform through a loose coupling, ‘plug and play’ manner. The proposed model and methods will provide the real-time, accurate, value-added and useful manufacturing information for optimal configuration and scheduling of large-scale manufacturing resources in a CMfg environment.

  • 7486.
    Zhang, Yumiao
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter. Linköpings universitet, Tekniska högskolan.
    Ultra-Low Power Input Driver for High-ResolutionDiscrete-Time Σ∆ Modulator2013Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This thesis presents the design of an input driver for ultra-low power sigmadelta modulator. High resolution Σ∆ ADCs are becoming more and more usefulin ultra-low power medical applications. Therefore, reducing supply voltage andpower starts a new chanllenges both at architecture as well as circuit performancelevel. Three input drivers are presented in this thesis making use of operationalamplifiers with the class AB buffers as output stage.In the thesis, the building blocks of the input buffer are described in detail.Two different designs are included in the thesis in order to achieve the specificationunder different conditions of the input signal. The specifications are 90 dB Signalto-Noiseand Distortion Ratio (SNDR) and 4 µW of the power consumption. Atwo stage achitectures with different building blocks is investigated. The buildingblocks are a single stage fully differential amplifier as the first stage and a classAB behavior unity gain buffer as the second stage. Design comparison is basedon the simulation results. The reasons for the different designs are mainly causedby design constraints, the input signal voltage level and the stability. Designconstraints are because of the trade-offs among structure of the building block,transistor threshold voltage and low power supply voltage. At the end of thisthesis project, we achieved 90dB SNDR in the first design by using Folded-VoltageFollower (FVF) structure in transistor level and an improved performance designin the second design.

  • 7487.
    Zhao, Dan
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Wang, Hui
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska fakulteten.
    Ullah Khan, Zia
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Chen, J. C.
    Xiamen University, Peoples R China.
    Gabrielsson, Roger
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Jonsson, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Berggren, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Crispin, Xavier
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska fakulteten.
    Ionic thermoelectric supercapacitors2016Ingår i: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 9, nr 4, s. 1450-1457Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Temperature gradients are generated by the sun and a vast array of technologies and can induce molecular concentration gradients in solutions via thermodiffusion (Soret effect). For ions, this leads to a thermovoltage that is determined by the thermal gradient Delta T across the electrolyte, together with the ionic Seebeck coefficient alpha(i). So far, redox-free electrolytes have been poorly explored in thermoelectric applications due to a lack of strategies to harvest the energy from the Soret effect. Here, we report the conversion of heat into stored charge via a remarkably strong ionic Soret effect in a polymeric electrolyte (Seebeck coefficients as high as alpha(i) = 10 mV K-1). The ionic thermoelectric supercapacitor (ITESC) is charged under a temperature gradient. After the temperature gradient is removed, the stored electrical energy can be delivered to an external circuit. This new means to harvest energy is particularly suitable for intermittent heat sources like the sun. We show that the stored electrical energy of the ITESC is proportional to (Delta T alpha(i))(2). The resulting ITESC can convert and store several thousand times more energy compared with a traditional thermoelectric generator connected in series with a supercapacitor.

  • 7488.
    Zhao, Haichuan Jianqiu Wu
    Linköpings universitet, Institutionen för systemteknik.
    Implementation and simulation of HSDPA functionality with ns-22005Självständigt arbete på grundnivå (yrkesexamen)Studentuppsats
    Abstract [en]

    Enhanced packet-data access is a trend in third generation mobile communication system. WCDMA Release 5 introduces HSDPA (High Speed Packet Data Access) with a brand new downlink transport channel HS-DSCH (High Speed Downlink Shared Channel) into 3GPP specification to provide greater capacity. HS-DSCH supports some new feature such as fast link adaptation, fast scheduling and fast HARQ (hybrid ARQ) so as to increase system performance. It efficiently improves power utilization, shortens retransmission time and increases system throughput.

    The focus for this thesis is implementation and simulation of HSDPA functionality with ns-2. There is some previous work has been done, such as EURANE. EURANE is an end to end extension which adds several HSDPA modules to ns-2. This paper addresses the analysis of HSDPA by simulating on HS-DSCH based on EURANE, and extends the power consumption on HS-DSCH.

  • 7489.
    Zhao, Jianning
    et al.
    IFP Energies Nouvelles, France.
    Sciarretta, Antonio
    IFP Energies Nouvelles, France.
    Eriksson, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    GRAB-ECO for Minimal Fuel Consumption Estimation of Parallel Hybrid Electric Vehicles2017Ingår i: Oil & gas science and technology, ISSN 1294-4475, E-ISSN 1953-8189, Vol. 72, nr 6, artikel-id 39Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    As a promising solution to the reduction of fuel consumption and CO2 emissions in road transport sector, hybrid electric powertrains are confronted with complex control techniques for the evaluation of the minimal fuel consumption, particularly the excessively long computation time of the design-parameter optimization in the powertrains early design stage. In this work, a novel and simple GRaphical-Analysis-Based method of fuel Energy Consumption Optimization (GRAB-ECO) is developed to estimate the minimal fuel consumption for parallel hybrid electric powertrains in light-and heavy-duty application. Based on the power ratio between powertrains power demand and the most efficient engine power, GRAB-ECO maximizes the average operating efficiency of the internal combustion engine by shifting operating points to the most efficient conditions, or by eliminating the engine operation from poorly efficient operating points to pure electric vehicle operation. A turning point is found to meet the requirement of the final state of energy of the battery, which is charge-sustaining mode in this study. The GRAB-ECO was tested with both light- and heavy-duty parallel hybrid electric vehicles, and validated in terms of the minimal fuel consumption and the computation time. Results show that GRAB-ECO accurately approximates the minimal fuel consumption with less than 6% of errors for both light-and heavy-duty parallel hybrid electric powertrains. Meanwhile, GRAB-ECO reduces computation time by orders of magnitude compared with PMP-based (Pontryagins Minimum Principle) approaches.

  • 7490.
    Zhao, Qingxiang
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Liu, Xinyu
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Holtz, Per-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Properties of shallow donors in ZnMgO epilayers grown by metal organic chemical vapor deposition2014Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 116, nr 18, s. 183508-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High quality Zn1-xMgxO epilayers have been grown by means of metal organic chemical vapor deposition technique on top of ZnO templates. The grown samples were investigated by x-ray photoelectron spectroscopy and photoluminescence. The magnesium (Mg) concentration was varied between 0% and 3% in order to study the properties of shallow donors. The free and donor bound excitons could be observed simultaneously in our high quality Zn1-xMgxO epilayers in the photoluminescence spectra. The results indicate that both built-in strain and Mg-concentration influence the donor exciton binding energy. It clearly shows that the donor exciton binding energy decreases with increasing Mg-concentration and with increasing built-in strain. Furthermore, the results indicate that the donor bound exciton transition energy increases with decreasing strength of the built-in strain if the Mg-concentration is kept the same in the Zn1-xMgxO epilayers.

  • 7491.
    Zhao, Yuxin
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Gaussian Processes for Positioning Using Radio Signal Strength Measurements2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Estimation of unknown parameters is considered as one of the major research areas in statistical signal processing. In the most recent decades, approaches in estimation theory have become more and more attractive in practical applications. Examples of such applications may include, but are not limited to, positioning using various measurable radio signals in indoor environments, self-navigation for autonomous cars, image processing, radar tracking and so on. One issue that is usually encountered when solving an estimation problem is to identify a good system model, which may have great impacts on the estimation performance. In this thesis, we are interested in studying estimation problems particularly in inferring the unknown positions from noisy radio signal measurements. In addition, the modeling of the system is studied by investigating the relationship between positions and radio signal strength measurements.

    One of the main contributions of this thesis is to propose a novel indoor positioning framework based on proximity measurements, which are obtained by quantizing the received signal strength measurements. Sequential Monte Carlo methods, to be more specific particle filter and smoother, are utilized for estimating unknown positions from proximity measurements. The Cramér-Rao bounds for proximity-based positioning are further derived as a benchmark for the positioning accuracy in this framework.

    Secondly, to improve the estimation performance, Bayesian non-parametric modeling, namely Gaussian processes, have been adopted to provide more accurate and flexible models for both dynamic motions and radio signal strength measurements. Then, the Cramér-Rao bounds for Gaussian process based system models are derived and evaluated in an indoor positioning scenario.

    In addition, we estimate the positions of stationary devices by comparing the individual signal strength measurements with a pre-constructed fingerprinting database. The positioning accuracy is further compared to the case where a moving device is positioned using a time series of radio signal strength measurements.

    Moreover, Gaussian processes have been applied to sports analytics, where trajectory modeling for athletes is studied. The proposed framework can be further utilized to carry out, for instance, performance prediction and analysis, health condition monitoring, etc. Finally, a grey-box modeling is proposed to analyze the forces, particularly in cross-country skiing races, by combining a deterministic kinetic model with Gaussian process.

    Delarbeten
    1. Received-Signal-Strength Threshold Optimization Using Gaussian Processes
    Öppna denna publikation i ny flik eller fönster >>Received-Signal-Strength Threshold Optimization Using Gaussian Processes
    2017 (Engelska)Ingår i: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 65, nr 8, s. 2164-2177Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    There is a big trend nowadays to use event-triggered proximity report for indoor positioning. This paper presents a generic received-signal-strength (RSS) threshold optimization framework for generating informative proximity reports. The proposed framework contains five main building blocks, namely the deployment information, RSS model, positioning metric selection, optimization process and management. Among others, we focus on Gaussian process regression (GPR)-based RSS models and positioning metric computation. The optimal RSS threshold is found through minimizing the best achievable localization root-mean-square-error formulated with the aid of fundamental lower bound analysis. Computational complexity is compared for different RSS models and different fundamental lower bounds. The resulting optimal RSS threshold enables enhanced performance of new fashioned low-cost and low-complex proximity report-based positioning algorithms. The proposed framework is validated with real measurements collected in an office area where bluetooth-low-energy (BLE) beacons are deployed.

    Ort, förlag, år, upplaga, sidor
    Institute of Electrical and Electronics Engineers (IEEE), 2017
    Nationell ämneskategori
    Elektroteknik och elektronik
    Identifikatorer
    urn:nbn:se:liu:diva-135065 (URN)10.1109/TSP.2017.2655480 (DOI)000395827100018 ()
    Projekt
    TRAX
    Anmärkning

    Funding agencies: European Union FP7 Marie Curie training programme on Tracking in Complex Sensor Systems [607400]

    Tillgänglig från: 2017-03-08 Skapad: 2017-03-08 Senast uppdaterad: 2019-02-12Bibliografiskt granskad
    2. Sequential Monte Carlo Methods and Theoretical Bounds for Proximity Report Based Indoor Positioning
    Öppna denna publikation i ny flik eller fönster >>Sequential Monte Carlo Methods and Theoretical Bounds for Proximity Report Based Indoor Positioning
    Visa övriga...
    2018 (Engelska)Ingår i: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 67, nr 6, s. 5372-5386Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    The commercial interest in proximity services is increasing. Application examples include location-based information and advertisements, logistics, social networking, file sharing, etc. In this paper, we consider positioning of devices based on a time series of proximity reports from a mobile device to a network node. This corresponds to nonlinear measurements with respect to the device position in relation to the network nodes. Motion model will be needed together with the measurements to determine the position of the device. Therefore, sequential Monte Carlo methods, namely particle filtering and smoothing, are applicable for positioning. Positioning performance is evaluated in a typical office area with Bluetooth-low-energy beacons deployed for proximity detection and report, and is further compared to parametric Cramér-Rao lower bounds. Finally, the position accuracy is also evaluated with real experimental data.

    Ort, förlag, år, upplaga, sidor
    Institute of Electrical and Electronics Engineers (IEEE), 2018
    Nyckelord
    Proximity, indoor positioning, particle filtering and smoothing, Cramer-Rao lower bounds
    Nationell ämneskategori
    Signalbehandling
    Identifikatorer
    urn:nbn:se:liu:diva-147834 (URN)10.1109/TVT.2018.2799174 (DOI)000435553400053 ()2-s2.0-85041415767 (Scopus ID)
    Anmärkning

    Funding agencies: European Union FP7 Marie Curie Training Programme on Tracking in Complex Sensor Systems (TRAX) [607400]; NSFC [61701426]; Shenzhen Science and Technology Innovation Council [JCYJ20170307155957688, JCYJ20170411102101881]

    Tillgänglig från: 2018-05-15 Skapad: 2018-05-15 Senast uppdaterad: 2019-02-12Bibliografiskt granskad
    3. Gaussian Process for Propagation modeling and Proximity Reports Based Indoor Positioning
    Öppna denna publikation i ny flik eller fönster >>Gaussian Process for Propagation modeling and Proximity Reports Based Indoor Positioning
    Visa övriga...
    2016 (Engelska)Ingår i: 2016 IEEE 83rd Vehicular Technology Conference (VTC Spring), IEEE , 2016, s. 1-5Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    The commercial interest in proximity services is increasing. Application examples include location-based information and advertisements, logistics, social networking, file sharing, etc. In this paper, we consider network-based positioning based on times series of proximity reports from a mobile device, either only a proximity indicator, or a vector of RSS from observed nodes. Such positioning corresponds to a latent and nonlinear observation model. To address these problems, we combine two powerful tools, namely particle filtering and Gaussian process regression (GPR) for radio signal propagation modeling. The latter also provides some insights into the spatial correlation of the radio propagation in the considered area. Radio propagation modeling and positioning performance are evaluated in a typical office area with Bluetooth-Low-Energy (BLE) beacons deployed for proximity detection and reports. Results show that the positioning accuracy can be improved by using GPR.

    Ort, förlag, år, upplaga, sidor
    IEEE, 2016
    Nationell ämneskategori
    Kommunikationssystem
    Identifikatorer
    urn:nbn:se:liu:diva-128255 (URN)10.1109/VTCSpring.2016.7504255 (DOI)000386528400206 ()9781509016983 (ISBN)
    Konferens
    2016 IEEE 83rd Vehicular Technology Conference: VTC2016-Spring, 15–18 May 2016, Nanjing, China
    Tillgänglig från: 2016-05-24 Skapad: 2016-05-24 Senast uppdaterad: 2019-02-12Bibliografiskt granskad
    4. Gaussian processes for RSS fingerprints construction in indoor localization
    Öppna denna publikation i ny flik eller fönster >>Gaussian processes for RSS fingerprints construction in indoor localization
    2018 (Engelska)Ingår i: 21st International Conference on Information Fusion (FUSION), IEEE, 2018, s. 1377-1384Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    Location-based applications attract more and more attention in recent years. Examples of such applications include commercial advertisements, social networking software and patient monitoring. The received signal strength (RSS) based location fingerprinting is one of the most popular solutions for indoor localization. However, there is a big challenge in collecting and maintaining a relatively large RSS fingerprint database. In this work, we propose and compare two algorithms namely, the Gaussian process (GP) and Gaussian process with variogram, to estimate and construct the RSS fingerprints with incomplete data. The fingerprint of unknown reference points is estimated based on measurements at a limited number of surrounding locations. To validate the effectiveness of both algorithms, experiments using Bluetooth-low-energy (BLE) infrastructure have been conducted. The constructed RSS fingerprints are compared to the true measurements, and the result is analyzed. Finally, using the constructed fingerprints, the localization performance of a probabilistic fingerprinting method is evaluated.

    Ort, förlag, år, upplaga, sidor
    IEEE, 2018
    Nationell ämneskategori
    Signalbehandling
    Identifikatorer
    urn:nbn:se:liu:diva-151693 (URN)10.23919/ICIF.2018.8455842 (DOI)978-0-9964527-6-2 (ISBN)
    Konferens
    21st International Conference on Information Fusion (FUSION), 10-13 July 2018, Cambridge, UK
    Tillgänglig från: 2018-10-01 Skapad: 2018-10-01 Senast uppdaterad: 2019-02-12
    5. Gaussian Processes for Flow Modeling and Prediction of Positioned Trajectories Evaluated with Sports Data
    Öppna denna publikation i ny flik eller fönster >>Gaussian Processes for Flow Modeling and Prediction of Positioned Trajectories Evaluated with Sports Data
    Visa övriga...
    2016 (Engelska)Ingår i: 19th International Conference on  Information Fusion (FUSION), 2016, Institute of Electrical and Electronics Engineers (IEEE), 2016, s. 1461-1468Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    Kernel-based machine learning methods are gaining increasing interest in flow modeling and prediction in recent years. Gaussian process (GP) is one example of such kernelbased methods, which can provide very good performance for nonlinear problems. In this work, we apply GP regression to flow modeling and prediction of athletes in ski races, but the proposed framework can be generally applied to other use cases with device trajectories of positioned data. Some specific aspects can be addressed when the data is periodic, like in sports where the event is split up over multiple laps along a specific track. Flow models of both the individual skier and a cluster of skiers are derived and analyzed. Performance has been evaluated using data from the Falun Nordic World Ski Championships 2015, in particular the Men’s cross country 4 × 10 km relay. The results show that the flow models vary spatially for different skiers and clusters. We further demonstrate that GP regression provides powerful and accurate models for flow prediction.

    Ort, förlag, år, upplaga, sidor
    Institute of Electrical and Electronics Engineers (IEEE), 2016
    Nationell ämneskategori
    Elektroteknik och elektronik Sannolikhetsteori och statistik
    Identifikatorer
    urn:nbn:se:liu:diva-129758 (URN)9780996452748 (ISBN)9781509020126 (ISBN)
    Konferens
    19th International Conference on Information Fusion, 5-8 July 2016, Heidelberg, Germany
    Tillgänglig från: 2016-06-27 Skapad: 2016-06-27 Senast uppdaterad: 2019-02-12Bibliografiskt granskad
  • 7492.
    Zhao, Yuxin
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Position Estimation in Uncertain Radio Environments and Trajectory Learning2017Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    To infer the hidden states from the noisy observations and make predictions based on a set of input states and output observations are two challenging problems in many research areas. Examples of applications many include position estimation from various measurable radio signals in indoor environments, self-navigation for autonomous cars, modeling and predicting of the traffic flows, and flow pattern analysis for crowds of people. In this thesis, we mainly use the Bayesian inference framework for position estimation in an indoor environment, where the radio propagation is uncertain. In Bayesian inference framework, it is usually hard to get analytical solutions. In such cases, we resort to Monte Carlo methods to solve the problem numerically. In addition, we apply Bayesian nonparametric modeling for trajectory learning in sport analytics.

    The main contribution of this thesis is to propose sequential Monte Carlo methods, namely particle filtering and smoothing, for a novel indoor positioning framework based on proximity reports. The experiment results have been further compared with theoretical bounds derived for this proximity based positioning system. To improve the performance, Bayesian non-parametric modeling, namely Gaussian process, has been applied to better indicate the radio propagation conditions. Then, the position estimates obtained sequentially using filtering and smoothing are further compared with a static solution, which is known as fingerprinting.

    Moreover, we propose a trajectory learning framework for flow estimation in sport analytics based on Gaussian processes. To mitigate the computation deficiency of Gaussian process, a grid-based on-line algorithm has been adopted for real-time applications. The resulting trajectory modeling for individual athlete can be used for many purposes, such as performance prediction and analysis, health condition monitoring, etc. Furthermore, we aim at modeling the flow of groups of athletes, which could be potentially used for flow pattern recognition, strategy planning, etc.

    Delarbeten
    1. Received-Signal-Strength Threshold Optimization Using Gaussian Processes
    Öppna denna publikation i ny flik eller fönster >>Received-Signal-Strength Threshold Optimization Using Gaussian Processes
    2017 (Engelska)Ingår i: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 65, nr 8, s. 2164-2177Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    There is a big trend nowadays to use event-triggered proximity report for indoor positioning. This paper presents a generic received-signal-strength (RSS) threshold optimization framework for generating informative proximity reports. The proposed framework contains five main building blocks, namely the deployment information, RSS model, positioning metric selection, optimization process and management. Among others, we focus on Gaussian process regression (GPR)-based RSS models and positioning metric computation. The optimal RSS threshold is found through minimizing the best achievable localization root-mean-square-error formulated with the aid of fundamental lower bound analysis. Computational complexity is compared for different RSS models and different fundamental lower bounds. The resulting optimal RSS threshold enables enhanced performance of new fashioned low-cost and low-complex proximity report-based positioning algorithms. The proposed framework is validated with real measurements collected in an office area where bluetooth-low-energy (BLE) beacons are deployed.

    Ort, förlag, år, upplaga, sidor
    Institute of Electrical and Electronics Engineers (IEEE), 2017
    Nationell ämneskategori
    Elektroteknik och elektronik
    Identifikatorer
    urn:nbn:se:liu:diva-135065 (URN)10.1109/TSP.2017.2655480 (DOI)000395827100018 ()
    Projekt
    TRAX
    Anmärkning

    Funding agencies: European Union FP7 Marie Curie training programme on Tracking in Complex Sensor Systems [607400]

    Tillgänglig från: 2017-03-08 Skapad: 2017-03-08 Senast uppdaterad: 2019-02-12Bibliografiskt granskad
    2. Gaussian Process for Propagation modeling and Proximity Reports Based Indoor Positioning
    Öppna denna publikation i ny flik eller fönster >>Gaussian Process for Propagation modeling and Proximity Reports Based Indoor Positioning
    Visa övriga...
    2016 (Engelska)Ingår i: 2016 IEEE 83rd Vehicular Technology Conference (VTC Spring), IEEE , 2016, s. 1-5Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    The commercial interest in proximity services is increasing. Application examples include location-based information and advertisements, logistics, social networking, file sharing, etc. In this paper, we consider network-based positioning based on times series of proximity reports from a mobile device, either only a proximity indicator, or a vector of RSS from observed nodes. Such positioning corresponds to a latent and nonlinear observation model. To address these problems, we combine two powerful tools, namely particle filtering and Gaussian process regression (GPR) for radio signal propagation modeling. The latter also provides some insights into the spatial correlation of the radio propagation in the considered area. Radio propagation modeling and positioning performance are evaluated in a typical office area with Bluetooth-Low-Energy (BLE) beacons deployed for proximity detection and reports. Results show that the positioning accuracy can be improved by using GPR.

    Ort, förlag, år, upplaga, sidor
    IEEE, 2016
    Nationell ämneskategori
    Kommunikationssystem
    Identifikatorer
    urn:nbn:se:liu:diva-128255 (URN)10.1109/VTCSpring.2016.7504255 (DOI)000386528400206 ()9781509016983 (ISBN)
    Konferens
    2016 IEEE 83rd Vehicular Technology Conference: VTC2016-Spring, 15–18 May 2016, Nanjing, China
    Tillgänglig från: 2016-05-24 Skapad: 2016-05-24 Senast uppdaterad: 2019-02-12Bibliografiskt granskad
    3. Gaussian Processes for Flow Modeling and Prediction of Positioned Trajectories Evaluated with Sports Data
    Öppna denna publikation i ny flik eller fönster >>Gaussian Processes for Flow Modeling and Prediction of Positioned Trajectories Evaluated with Sports Data
    Visa övriga...
    2016 (Engelska)Ingår i: 19th International Conference on  Information Fusion (FUSION), 2016, Institute of Electrical and Electronics Engineers (IEEE), 2016, s. 1461-1468Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    Kernel-based machine learning methods are gaining increasing interest in flow modeling and prediction in recent years. Gaussian process (GP) is one example of such kernelbased methods, which can provide very good performance for nonlinear problems. In this work, we apply GP regression to flow modeling and prediction of athletes in ski races, but the proposed framework can be generally applied to other use cases with device trajectories of positioned data. Some specific aspects can be addressed when the data is periodic, like in sports where the event is split up over multiple laps along a specific track. Flow models of both the individual skier and a cluster of skiers are derived and analyzed. Performance has been evaluated using data from the Falun Nordic World Ski Championships 2015, in particular the Men’s cross country 4 × 10 km relay. The results show that the flow models vary spatially for different skiers and clusters. We further demonstrate that GP regression provides powerful and accurate models for flow prediction.

    Ort, förlag, år, upplaga, sidor
    Institute of Electrical and Electronics Engineers (IEEE), 2016
    Nationell ämneskategori
    Elektroteknik och elektronik Sannolikhetsteori och statistik
    Identifikatorer
    urn:nbn:se:liu:diva-129758 (URN)9780996452748 (ISBN)9781509020126 (ISBN)
    Konferens
    19th International Conference on Information Fusion, 5-8 July 2016, Heidelberg, Germany
    Tillgänglig från: 2016-06-27 Skapad: 2016-06-27 Senast uppdaterad: 2019-02-12Bibliografiskt granskad
  • 7493.
    Zhao, Yuxin
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Fritsche, Carsten
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Supplementary Materials for "Sequential Monte Carlo Methods and Theoretical Bounds for Proximity Report based Indoor Positioning"2017Rapport (Övrigt vetenskapligt)
    Abstract [en]

    This reportontains supplementary material for the paper [1].

  • 7494.
    Zhao, Yuxin
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Fritsche, Carsten
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Gunnarsson, Fredrik
    Ericsson AB.
    Parametric Lower Bound for Nonlinear Filteringbased on Gaussian Process Regression Model2017Ingår i: 2017 20th International Conference on Information Fusion (Fusion), IEEE, 2017, s. 1-7Konferensbidrag (Refereegranskat)
    Abstract [en]

    Assessing the fundamental performance limitationsin Bayesian filtering can be carried out using the parametricCram´er-Rao bound (CRB). The parametric CRB puts a lowerbound on mean square error (MSE) matrix conditioned on aspecific state trajectory realization. In this work, we derive theparametric CRB for state-space models, where the measurementequation is modeled by a Gaussian process regression.These models appear, for instance in proximity report-basedpositioning, where proximity reports are obtained by hardthresholding of received signal strength (RSS) measurements, thatare modeled through Gaussian process regression. The proposedparametric CRB is evaluated on selected state trajectories andfurther compared with the positioning performance obtained bythe particle filter. The results corroborate that the positioningaccuracy achieved in this framework is close to the parametricCRB.

  • 7495.
    Zhao, Yuxin
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten. Ericsson.
    Fritsche, Carsten
    Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Institutionen för systemteknik, Reglerteknik.
    Hendeby, Gustaf
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan. Linköpings universitet, Tekniska fakulteten. Linköping University.
    Yin, Feng
    Chinese University of Hong Kong (Shenzhen).
    Chen, Tianshi
    Chinese University of Hong Kong (Shenzhen).
    Gunnarsson, Fredrik
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Cramér–Rao Bounds for Filtering Based on Gaussian Process State-Space Models2019Ingår i: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 67, nr 23, s. 5936-5951Artikel i tidskrift (Refereegranskat)
  • 7496.
    Zhao, Yuxin
    et al.
    Research, Ericsson AB, 39174 Stockholm, Sweden.
    Fritsche, Carsten
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Yin, Feng
    SSE, Chinese University of Hong Kong Shenzhen, Shenzhen, China.
    Gunnarsson, Fredrik
    Ericsson Research, Linköping, Sweden.
    Gustafsson, Fredrik
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Sequential Monte Carlo Methods and Theoretical Bounds for Proximity Report Based Indoor Positioning2018Ingår i: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 67, nr 6, s. 5372-5386Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The commercial interest in proximity services is increasing. Application examples include location-based information and advertisements, logistics, social networking, file sharing, etc. In this paper, we consider positioning of devices based on a time series of proximity reports from a mobile device to a network node. This corresponds to nonlinear measurements with respect to the device position in relation to the network nodes. Motion model will be needed together with the measurements to determine the position of the device. Therefore, sequential Monte Carlo methods, namely particle filtering and smoothing, are applicable for positioning. Positioning performance is evaluated in a typical office area with Bluetooth-low-energy beacons deployed for proximity detection and report, and is further compared to parametric Cramér-Rao lower bounds. Finally, the position accuracy is also evaluated with real experimental data.

  • 7497.
    Zhao, Yuxin
    et al.
    Ericsson AB, Sverige.
    Liu, Chao
    University of Sheffield, UK.
    Mihaylova, Lyudmila S.
    University of Sheffield, UK.
    Gunnarsson, Fredrik
    Ericsson AB, Sverige.
    Gaussian processes for RSS fingerprints construction in indoor localization2018Ingår i: 21st International Conference on Information Fusion (FUSION), IEEE, 2018, s. 1377-1384Konferensbidrag (Refereegranskat)
    Abstract [en]

    Location-based applications attract more and more attention in recent years. Examples of such applications include commercial advertisements, social networking software and patient monitoring. The received signal strength (RSS) based location fingerprinting is one of the most popular solutions for indoor localization. However, there is a big challenge in collecting and maintaining a relatively large RSS fingerprint database. In this work, we propose and compare two algorithms namely, the Gaussian process (GP) and Gaussian process with variogram, to estimate and construct the RSS fingerprints with incomplete data. The fingerprint of unknown reference points is estimated based on measurements at a limited number of surrounding locations. To validate the effectiveness of both algorithms, experiments using Bluetooth-low-energy (BLE) infrastructure have been conducted. The constructed RSS fingerprints are compared to the true measurements, and the result is analyzed. Finally, using the constructed fingerprints, the localization performance of a probabilistic fingerprinting method is evaluated.

  • 7498.
    Zhao, Yuxin
    et al.
    Ericsson Research, Linköping, Sweden.
    Yin, Feng
    Ericsson Research, Linköping, Sweden.
    Gunnarsson, Fredrik
    Ericsson Research, Linköping, Sweden.
    Amirijoo, Mehdi
    Ericsson Research, Linköping, Sweden.
    Hendeby, Gustaf
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Gaussian Process for Propagation modeling and Proximity Reports Based Indoor Positioning2016Ingår i: 2016 IEEE 83rd Vehicular Technology Conference (VTC Spring), IEEE , 2016, s. 1-5Konferensbidrag (Refereegranskat)
    Abstract [en]

    The commercial interest in proximity services is increasing. Application examples include location-based information and advertisements, logistics, social networking, file sharing, etc. In this paper, we consider network-based positioning based on times series of proximity reports from a mobile device, either only a proximity indicator, or a vector of RSS from observed nodes. Such positioning corresponds to a latent and nonlinear observation model. To address these problems, we combine two powerful tools, namely particle filtering and Gaussian process regression (GPR) for radio signal propagation modeling. The latter also provides some insights into the spatial correlation of the radio propagation in the considered area. Radio propagation modeling and positioning performance are evaluated in a typical office area with Bluetooth-Low-Energy (BLE) beacons deployed for proximity detection and reports. Results show that the positioning accuracy can be improved by using GPR.

  • 7499.
    Zhao, Yuxin
    et al.
    Ericsson Research, Linköping, Sweden.
    Yin, Feng
    Ericsson Research, Linköping, Sweden.
    Gunnarsson, Fredrik
    Ericsson Research, Linköping, Sweden.
    Amirijoo, Mehdi
    Ericsson Research, Linköping, Sweden.
    Özkan, Emre
    ISY, Linköping University.
    Gustafsson, Fredrik
    ISY, Linköping University.
    Particle Filtering for Positioning Based on Proximity Reports2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    The commercial interest in proximity services is increasing. Application examples include location-based information and advertisements, logistics, social networking, file sharing, etc. In this paper, we consider positioning of devices based on time series proximity reports from a mobile device to a network node. This corresponds to nonlinear measurements with respect to the device position in relation to the network nodes. Therefore, particle filtering is applicable for positioning. Positioning performance is evaluated in a typical office area with Bluetooth-low-energy beacons deployed for proximity detection and report. Accuracy is concluded to vary spatially over the office floor, and in relation to the beacon deployment density.

  • 7500.
    Zhao, Yuxin
    et al.
    Ericsson AB, Sweden.
    Yin, Feng
    Ericsson AB, Sweden.
    Gunnarsson, Fredrik
    Ericsson AB, Sweden.
    Hultkratz, Fredrik
    Ericsson AB, Sweden.
    Fagerlind, Johan
    Ericsson AB, Sweden.
    Gaussian Processes for Flow Modeling and Prediction of Positioned Trajectories Evaluated with Sports Data2016Ingår i: 19th International Conference on  Information Fusion (FUSION), 2016, Institute of Electrical and Electronics Engineers (IEEE), 2016, s. 1461-1468Konferensbidrag (Refereegranskat)
    Abstract [en]

    Kernel-based machine learning methods are gaining increasing interest in flow modeling and prediction in recent years. Gaussian process (GP) is one example of such kernelbased methods, which can provide very good performance for nonlinear problems. In this work, we apply GP regression to flow modeling and prediction of athletes in ski races, but the proposed framework can be generally applied to other use cases with device trajectories of positioned data. Some specific aspects can be addressed when the data is periodic, like in sports where the event is split up over multiple laps along a specific track. Flow models of both the individual skier and a cluster of skiers are derived and analyzed. Performance has been evaluated using data from the Falun Nordic World Ski Championships 2015, in particular the Men’s cross country 4 × 10 km relay. The results show that the flow models vary spatially for different skiers and clusters. We further demonstrate that GP regression provides powerful and accurate models for flow prediction.

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