liu.seSök publikationer i DiVA
Ändra sökning
Avgränsa sökresultatet
1234567 51 - 100 av 7491
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 51.
    Ahlberg, Sven
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska högskolan.
    Evaluation of Different Radio-Based Indoor Positioning Methods2014Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Today, positioning with GPS and the advantages this entails are almost infinitive, which means that the technology can be utilized in a variety of applications. Unfortunately, there exists a lot of limitations in conjunction with the signals from the GPS can’t reach inside e.g. buildings or underground. This means that an alternative solution that works indoors needs to be developed.

    The report presents the four most common radio-based technologies, Bluetooth,Wi-Fi, UWB and RFID, which can be used to determine a position. These all have different advantages in cost, accuracy and latency, which means that there exist a number of different applications.

    The radio-based methods use the measurement techniques, RSSI, TOA, TDOA, Cell-ID, PD or AOA to gather data. The choice of measurement technique is mainly dependent of which radio-based method being used, since their accuracy depends on the quality of the measurements and the size of the detection area, which means that all measurement techniques have different advantages and disadvantages.

    The measurement data is processed with one of the positioning methods, LS, NLS, ML, Cell-ID, WC or FP, to estimate a position. The choice of positioning method also depends on the quality of the measurements in combination with the size of the detection area.

    To evaluate the different radio-based methods together with measurement techniques and positioning methods, accuracy, latency and cost are being compared. This is used as the basis for the choice of positioning method, since a general solution can get summarized by finding the least expensive approach which can estimate an unknown position with sufficiently high accuracy.

  • 52.
    Ahlgren, Simon
    et al.
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Aini, Daniel
    Linköpings universitet, Institutionen för datavetenskap, Programvara och system.
    Conversion and Analysis of Telemetric Data from the CCSDS Standard2017Självständigt arbete på grundnivå (högskoleexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [en]

    When communicating with spacecrafts, the international standard is to use the protocols defined by CCSDS. In this study, the Space Packet Protocol from CCSDS is converted to the Digital Recording Standard used in aviation. The goal of the study is to find out in what way such a conversion can be made, as well as analyzing the efficiency of different packing methods for the Digital Recording Standard. An application is developed in order to perform the conversion, and the performance of said application is profiled using different packet sizes. In the end the results are evaluated and an optimal packet size is found in terms of runtime and memory usage. In the end we conclude that a packet size of 216 bytes is best when prioritizing speed, and a packet size of 219 bytes is best when prioritizing memory.

  • 53.
    Ahlin, Karl
    Linköpings universitet, Institutionen för systemteknik.
    Quality of Service i IP-nätverk2003Självständigt arbete på grundnivå (yrkesexamen)Studentuppsats
    Abstract [en]

    The original promise behind the Internet Protocol was to deliver data from a sender to the receiver using a best-effort approach. This means that the protocol makes no guarantees except that it will try to deliver the data to the destination. If some problem occurs the packet may be discarded by the network without any notice. No guarantees are made regarding the time it takes to deliver the data, the rate at which data will be delivered or if data is delivered in the same order it was sent. The best-effort approach is arguably the reason behind the success of the Internet Protocol and is what makes IP scalable to networks the size of the Internet. However, this approach is also a problem for network operators who want to offer better quality of service to some of their customers. This master thesis will discuss some of the theories behind the implementation of quality of service schemes in an IP network and also provide an example of how to implement it in an existing network.

  • 54.
    Ahlqvist, Johan
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem.
    Evaluation of the Turbo-decoder Coprocessor on a TMS320C64x Digital Signal Processor2011Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    En teknik som används för att minska de fel som en signal utsätts för vid transmission över en brusig kanal är felrättande kodning. Ett exempel på sådan kodning som ger ett mycket bra resultat är turbokodning. I några digitalsignalprocessorer, av sorten TMS320C64xTM, finns en inbyggd coprocessor som utför turboavkodning.

    Denna uppsats är utförd åt Communication Development inom Saab AB och presenterar en utvärdering av denna coprocessor. Utvärderingen avser såväl minnesförbrukning som datatakt och innehåller även en jämförelse med en implementering av turbokodning utan att använda coprocessorn.

  • 55.
    Ahlström, Christer
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik.
    Liljefeldt, Olle
    Hult, Peter
    Linköpings universitet, Institutionen för medicinsk teknik.
    Ask, Per
    Linköpings universitet, Institutionen för medicinsk teknik.
    Heart sound cancellation from lung sound recordings using recurrence time statistics and nonlinear prediction.2005Ingår i: Medicinteknikdagarna, 2005, Vol. 12, s. 812-815Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Heart sounds (HS) obscure the interpretation of lung sounds (LS). This letter presents a new method to detect and remove this undesired disturbance. The HS detection algorithm is based on a recurrence time statistic that is sensitive to changes in a reconstructed state space. Signal segments that are found to contain HS are removed, and the arising missing parts are replaced with predicted LS using a nonlinear prediction scheme. The prediction operates in the reconstructed state space and uses an iterated integrated nearest trajectory algorithm. The HS detection algorithm detects HS with an error rate of 4% false positives and 8% false negatives. The spectral difference between the reconstructed LS signal and an LS signal with removed HS was 0 34 0 25, 0 50 0 33, 0 46 0 35, and 0 94 0 64 dB/Hz in the frequency bands 20–40, 40–70, 70–150, and 150–300 Hz, respectively. The cross-correlation index was found to be 99.7%, indicating excellent similarity between actual LS and predicted LS. Listening tests performed by a skilled physician showed high-quality auditory results.

  • 56.
    Ahlström, Linus
    Linköpings universitet, Institutionen för systemteknik.
    Algoritmer för objektdetektering i SAR och IR-bilder2003Självständigt arbete på grundnivå (yrkesexamen)Studentuppsats
    Abstract [en]

    The first part of the thesis consists of a brief introduction to the general principles of target detection and the sensor-systems used. In the following part there is a theoretical description of the algorithms this thesis focuses on. The detection algorithms described in this paper are called Cell Average, Ordered Statistics, 2parameter and Gammadetector. Two different discriminators called Extended Fractal Features and Quadratic Gamma Discriminator are also described. The algorithms are tested on three different types of data, simulated SAR-pictures, authentic SAR-targets and IR-pictures. The last part account for the results, both those achieved with pictures and those results achieved when doing statistical tests, in this case MonteCarlo- simulations and Reciever Operating Characteristics-curves. The results show that the Gamma- detector and the QGD-algorithm perform best on the tests done in this thesis.

  • 57.
    Ahlström, Per
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska högskolan.
    Signalprediktering i vitt gaussiskt brus med hjälp av ett adaptivt signalanpassat filter1976Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Ett signalanpassat filter har ett impulssvar som är den exiterandesignalens spegelbild . Ett dylikt filter maximerar vid en viss tidpunkt signalbrusförhållandet på utgången.

    Ett adaptivt transversalfilter styrt av en gradientkännande algoritm, vilken maximerar signalbrusförhållandet på filterutgången, har studerats. Det spegelvända impulssvaret har använts som prediktion av signalen. Denna prediktion har, vid simulering gjord på dator, ej visat sig vara bättre än en klassisk prediktion med en ren summering av brusstörda upplagor av signalen. Inte ens då dylika summerade upplagor av den brusstörda signalenanvänts som insignal till filtret har signalprediktionen via filtrets impulssvar uppvisat ett lägre kvadratiskt medelfel än d en klassiska.

  • 58.
    Ahmad, Ijaz
    et al.
    University of Oulu, Finland.
    Kumar, Tanesh
    University of Oulu, Finland.
    Liyanage, Madhusanka
    University of Oulu, Finland.
    Okwuibe, Jude
    University of Oulu, Finland.
    Ylianttila, Mika
    University of Oulu, Finland.
    Gurtov, Andrei
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    5G Security: Analysis of Threats and Solutions2017Ingår i: 2017 IEEE CONFERENCE ON STANDARDS FOR COMMUNICATIONS AND NETWORKING (CSCN), IEEE , 2017, s. 193-199Konferensbidrag (Refereegranskat)
    Abstract [en]

    5G will provide broadband access everywhere, entertain higher user mobility, and enable connectivity of massive number of devices (e.g. Internet of Things (IoT)) in an ultrareliable and affordable way. The main technological enablers such as cloud computing, Software Defined Networking (SDN) and Network Function Virtualization (NFV) are maturing towards their use in 5G. However, there are pressing security challenges in these technologies besides the growing concerns for user privacy. In this paper, we provide an overview of the security challenges in these technologies and the issues of privacy in 5G. Furthermore, we present security solutions to these challenges and future directions for secure 5G systems.

  • 59.
    Ahmad, Ijaz
    et al.
    Univ Oulu, Finland.
    Liyanage, Madhusanka
    Univ Oulu, Finland.
    Ylianttila, Mika
    Univ Oulu, Finland.
    Gurtov, Andrei
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Analysis of Deployment Challenges of Host Identity Protocol2017Ingår i: 2017 EUROPEAN CONFERENCE ON NETWORKS AND COMMUNICATIONS (EUCNC), IEEE , 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    Host Identity Protocol (HIP), a novel internetworking technology proposes separation of the identity-location roles of the Internet Protocol (IP). HIP has been successful from the technological perspectives for network security and mobility, however, it has very limited deployment. In this paper we assess HIP to find the reasons behind its limited deployment and highlight the challenges faced by HIP for its commercial use. We propose technological development and outline deployment strategies for the wide use of HIP. Furthermore, this paper investigates the use of HIP in Software Defined Networks (SDN) to evaluate its performance in new disruptive networking technologies. In a nutshell, this paper presents revealing challenges for the deployment of innovative networking protocols and a way ahead for successful and large scale deployment.

  • 60.
    Ahmad, Shakeel
    et al.
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter. Linköpings universitet, Tekniska högskolan.
    Dabrowski, Jerzy
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter. Linköpings universitet, Tekniska högskolan.
    Cancellation of Spurious Spectral Components in One-Bit Stimuli Generator2010Ingår i: Proceedings of IEEEInternational Conference on Signals and Electronic Systems, (ICSES 10) / [ed] Andrzej Pułka and Tomasz Golonek, IEEE , 2010, s. 393-396Konferensbidrag (Refereegranskat)
    Abstract [en]

    This work presents a cancellation technique of non-linear distortion components of one-bit digital stimulus sequence which is generated in software by a ΣΔ modulator. The stimulus is stored in a cyclic memory and applied to a circuit under test through a driving buffer and a simple lowpass reconstruction filter. The distortion components originate from buffer imperfections which result in a possible asymmetry between rising and falling edges of a NRTZ waveform representing the encoded stimulus. We show that the distortion components can be cancelled by using a simple predistortion technique. In addition an on-chip DC-calibrated ADC can be used to identify the second-order nonlinear products of the driving buffer. This procedure allows for cancellation of all the second-order distortions before the actual test and it can be extended to the third order terms as well.

  • 61.
    Ahmad, Shakeel
    et al.
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter. Linköpings universitet, Tekniska högskolan.
    Dabrowski, Jerzy
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter. Linköpings universitet, Tekniska högskolan.
    On-Chip Spectral Test for High-Speed ADCs by ΣΔ Technique2011Ingår i: European Conference on Circuit Theory and Design (ECCTD), Linköping, Sweden: IEEE conference proceedings, 2011, s. 661-664Konferensbidrag (Refereegranskat)
    Abstract [en]

    Application of the ΣΔ modulation technique to the on-chip spectral test for high-speed A/D converters is presented. The harmonic HD2/HD3 and intermodulation IM2/IM3 test is obtained with one-bit ΣΔ sequence stored in a cyclic memory or generated on line, and applied to an ADC under test through a driving buffer and a simple reconstruction filter. To achieve a dynamic range (DR) suitable for high-performance spectral measurements a frequency plan is used taking into account the type of ΣΔ modulation (low-pass and band-pass) including the FFT processing gain. Higher order modulation schemes are avoided to manage the ΣΔ quantization noise without resorting to a more complicated filter. For spectral measurements up to the Nyquist frequency, we propose a dedicated low-pass/band-pass ΣΔ modulation scheme that limits spreading of the low-frequency quantization noise by ADC under test that tends to obstruct the test measurements at high frequencies. Correction technique for NRTZ encoding suitable for ADCs with very high clock frequencies is put in perspective. The presented technique is illustrated by simulation examples of a Nyquist-rate ADC under test.

  • 62.
    Ahmad, Shakeel
    et al.
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter. Linköpings universitet, Tekniska högskolan.
    Dabrowski, Jerzy
    Linköpings universitet, Institutionen för systemteknik, Elektroniska komponenter. Linköpings universitet, Tekniska högskolan.
    On-chip Stimuli Generation for ADC Dynamic Test by ΣΔ Technique2009Ingår i: Proceedings in European Conference on Circuit Theory and Design 2009 (ECCTD´09), Antalya, Turkey, IEEE , 2009, s. 105-108Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents application of the ΣΔ modulation technique to the on-chip dynamic test for A/D converters. The wanted stimulus such as a single- or two-tone signal is encoded into one-bit ΣΔ sequence, which after simple low-pass filtering is applied to the circuit under test with low noise and without distortion. In this way a large dynamic range is achieved making the performance harmonic- and intermodulation dynamic test viable. By a systematic approach we select the order and type of a ΣΔ modulator, and develop the frequency plan suitable for spectral measurements on a chip. The technique is illustrated by simulation of a practical ADC under test.

  • 63.
    Ahmadi, Shervin Parvini
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Hansson, Anders
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska fakulteten.
    Parallel Exploitation for Tree-Structured Coupled Quadratic Programming in Julia2018Ingår i: Proceedings of the 22nd International Conference on System Theory, Control and Computing, IEEE, 2018, s. 597-602Konferensbidrag (Refereegranskat)
    Abstract [en]

    The main idea in this paper is to implement a distributed primal-dual interior-point algorithm for loosely coupled Quadratic Programming problems. We implement this in Julia and show how can we exploit parallelism in order to increase the computational speed. We investigate the performance of the algorithm on a Model Predictive Control problem.

  • 64.
    Ahmed Aamir, Syed
    et al.
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska högskolan.
    Harikumar, Prakash
    Linköpings universitet, Institutionen för systemteknik, Elektroniksystem. Linköpings universitet, Tekniska högskolan.
    Wikner, Jacob J
    Linköpings universitet, Institutionen för systemteknik, Elektroniksystem. Linköpings universitet, Tekniska högskolan.
    Frequency compensation of high-speed, low-voltage CMOS multistage amplifiers2013Ingår i: IEEE International Symposium on Circuits and Systems (ISCAS), 2013, IEEE conference proceedings, 2013, s. 381-384Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents the frequency compensation of high-speed, low-voltage multistage amplifiers. Two frequency compensation techniques, the Nested Miller Compensation with Nulling Resistors (NMCNR) and Reversed Nested Indirect Compensation (RNIC), are discussed and employed on two multistage amplifier architectures. A four-stage pseudo-differential amplifier with CMFF and CMFB is designed in a 1.2 V, 65-nm CMOS process. With NMCNR, it achieves a phase margin (PM) of 59° with a DC gain of 75 dB and unity-gain frequency (fug) of 712 MHz. With RNIC, the same four-stage amplifier achieves a phase margin of 84°, DC gain of 76 dB and fug of 2 GHz. Further, a three-stage single-ended amplifier is designed in a 1.1-V, 40-nm CMOS process. The three-stage OTA with RNIC achieves PM of 81°, DC gain of 80 dB and fug of 770 MHz. The same OTA achieves PM of 59° with NMCNR, while maintaining a DC gain of 75 dB and fug of 262 MHz. Pole-splitting, to achieve increased stability, is illustrated for both compensation schemes. Simulations illustrate that the RNIC scheme achieves much higher PM and fug for lower values of compensation capacitance compared to NMCNR, despite the growing number of low voltage amplifier stages.

  • 65.
    Ahmed, Atheeq
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem.
    Human Detection Using Ultra Wideband Radar and Continuous Wave Radar2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    A radar works by radiating electromagnetic energy and detecting the reflected signal returned from the target. The nature of the reflected signal provides information about the target’s distance or speed. In this thesis, we will be using a UWB radar and a CW radar to help detect the presence and rough location of trapped survivors by detecting their motions. Range is estimated in the UWB radar using clutter removal with SVD and for the dual frequency CW Radar using STFT and median filtering. The effect of the algorithm parameters on their performance was analyzed. The performance of the implemented algorithms with regards to small motion detection, distance estimation and penetration capability was analyzed. Both systems are certainly capable of human detection and tracking.

  • 66.
    Ahmed, Ijaz
    et al.
    Centre for Wireless Communications, University of Oulu, Finland; VTT Technical Research Centre of Finland.
    Shahabuddin, Shahriar
    Centre for Wireless Communications, University of Oulu, Finland; Nokia, Oulu, Finland.
    Tanesh, Kumar
    Centre for Wireless Communications, University of Oulu, Finland.
    Okwuibe, Jude
    Centre for Wireless Communications, University of Oulu, Finland.
    Gurtov, Andrei
    Linköpings universitet, Institutionen för datavetenskap, Databas och informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Ylianttila, Mika
    Centre for Wireless Communications, University of Oulu, Finland.
    Security for 5G and Beyond2019Ingår i: IEEE Communications Surveys and Tutorials, ISSN 1553-877X, E-ISSN 1553-877XArtikel i tidskrift (Refereegranskat)
    Abstract [en]

    The development of the Fifth Generation (5G) wireless networks is gaining momentum to connect almost all aspects of life through the network with much higher speed, very low latency and ubiquitous connectivity. Due to its crucial role in our lives, the network must secure its users, components, and services. The security threat landscape of 5G has grown enormously due to the unprecedented increase in types of services and in the number of devices. Therefore, security solutions if not developed yet must be envisioned already to cope with diverse threats on various services, novel technologies, and increased user information accessible by the network. This article outlines the 5G network threat landscape, the security vulnerabilities in the new technological concepts that will be adopted by 5G, and provides either solutions to those threats or future directions to cope with those security challenges. We also provide a brief outline of the post-5G cellular technologies and their security vulnerabilities which is referred to as Future Generations (XG) in this paper. In brief, this article highlights the present and future security challenges in wireless networks, mainly in 5G, and future directions to secure wireless networks beyond 5G.

  • 67.
    Ahmed, Mohsin Niaz
    Linköpings universitet, Institutionen för systemteknik, Datorteknik.
    LTE Uplink Modeling and Channel Estimation2011Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This master thesis investigates the uplink transmition from User Equipment (UE) to base station in LET (Long Term Evolution) and channel estimation using pilot symbols with parameter defined in 3GPP (3rd Generation Partnership Project) specifications. The purpose of the thesis was to implement a simulator which can generate uplink signal as it is generated by UE. The Third Generation (3G) mobile system was given the name LTE. This thesis focus on the uplink of LTE where single carrier frequency division multiple access (SC-FDMA) is utilized as a multiple access technique. The advantage over the orthogonal frequency division multiple access (OFDMA), which is used in downlink is to get better peak power characteristics. Because in uplink communication better peak power characteristic is necessary for better power efficiency in mobile terminals. To access the performance of uplink transmition realistic channel model for wireless communication system is essential. Channel models used are proposed by International Telecommunication Union (ITU) and the correct knowledge of these models is important for testing, optimization and performance improvements of signal processing algorithms. The channel estimation techniques used are Least Square (LS) and Least Minimum Mean Square Error (LMMSE) for different channel models. Performance of these algorithms has been measured in term of Bit Error Rate (BER) and Signal to Noise Ratio (SNR).

  • 68.
    Ahmed, Tanvir
    Linköpings universitet, Institutionen för systemteknik, Elektroniksystem.
    High Level Model of IEEE 802.15.3c Standard and Implementation of a Suitable FFT on ASIC2011Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    A high level model of HSIPHY mode of IEEE 802.15.3c standard has been constructedin Matlab to optimize the wordlength to achieve a specific bit error rate (BER) depending on the application, and later an FFT has been implemented for different wordlengths depending on the applications. The hardware cost and power is proportional to wordlength. However, the main objective of this thesis has been to implement a low power, low area cost FFT for this standard. For that the whole system has been modeled in Matlab and the signal to noise ratio (SNR) and wordlength of the system have been studied to achieve an acceptable BER. Later an FFT has been implemented on 65nm ASIC for a wordlength of 8, 12 and 16 bits. For the implementation, a Radix-8 algorithm with eight parallel samples has been adopted. That reduce the area and the power consumption significantly compared to other algorithms and architectures. Moreover, a simple control has been used for this implementation. Voltage scaling has been done to reduce thepower. The EDA synthesis result shows that for 16bit wordlength, the FFT has 2.64 GS/s throughput, it takes 1.439 mm2 area on the chip and consume 61.51mW power.

  • 69.
    Ahmed, Zubair
    Linköpings universitet, Institutionen för systemteknik, Elektroniksystem. Linköpings universitet, Tekniska högskolan.
    Design of Autonomous Low Power Sensor for Soil Moisture Measurement.2013Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Drought is the most severe disaster compared to other disasters in human civilization and their impacts are serious which can cause hungur, thrist, food shortages, loss of livestock directly effects the human life. The main objective of this project is to develop an early warning system (EWS) [3] for drought indices by using wireless sensor networks (WSNs) which is the only way forward for an on-site monitoring and validation of locally defined drought indices [3].The designed wireless sensor network (WSN) consisting of a sensor unit, a master unit and a sensor power management unit (PMU). The sensor unit measures the moisture of the soil and transmitt the measured data through ZigBee module to the master unit. A real time clock (RTC) is also used in the sensor unit which records the information of second, minute, hour, day, month of day and year about when or what time the measurement taken. The master unit consisting of a SD-card and Bluetooth module. SD-card is used to store measured data from other sensor units and it is possible to take out the reading of measured data from the master unit by accessing the SD-card via Bluetooth inside the master unit to a PC or a smartphone mobile.To manage the power in the sensor unit and to make sensor alive for several years, the power management unit (PMU) manages the power level between two energy storage buffers (i.e., a supercapacitor and a Li+ ion battery) for a sensor node.

  • 70.
    Ahola, David
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    Yin To, Jie
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Kommunikations- och transportsystem. Linköpings universitet, Tekniska högskolan.
    To be entered/Green Cargo2013Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Schemakonstruktion för järnvägspersonal är en stor utmaning. En orsak är att arbetsuppgifterna vid järnvägen kräver olika kunskaps- och kompetenskrav, samt att det finns många arbetsregler som utgör restriktioner för schemakonstruktionen. I detta examensarbete har en fallstudie utförts för datorstödd schemakonstruktion för personalbemanning. Examensarbetet har utförts vid avdelningen för bemanningsplanering som ansvarar för planering av personal vid två av Green Cargos olika bangårdar. Huvudsyftet med det här examensarbetet är att utreda skillnaderna i scheman som skapats manuellt respektive automatiskt med hjälp av programvaran BP. Schemajämförelserna ska också redovisa nyttan av det automatiska planeringssättet där det finns applicerat. Under arbetet genomfördes litteraturstudier samt en fallstudie. I fallstudien genomfördes testkörningar med olika schemakonstruktionsmetoder på två bangårdar. Det numeriska resultatet visar att den datorassisterade bemanningsmetoden innebär en förbättrad bemanningsplanering ur företagets synvinkel då produktionsbehovet kan täckas utan ökade kostnader. Detta innebär också en ökad flexibilitet i produktionsplaneringen då tjänstgöringsturer enkelt kan ändras. Det gör det också mycket enklare att tilldela personal olika arbetsuppgifter som de har kompetens för. Den optimeringsbaserade bemanningsplanen innebär inte en ökad arbetsbelastning för medarbetaren. Trots att fler bangårdstjänster kan bemannas genom att använda den datorassisterade metoden visar det sig att den totala utlagda arbetstiden inte alls ökar eller att den bara ökar marginellt för vissa medarbetare. När planering sker med programvaran styrs denna av parametrar som är lätta att ändra. Dessa inställningar av parametrar är avgörande för utseendet på schemat. Indata kan vara fridagsplanering, kompetenstillgång och produktionsbehov. De i sin tur avgör i betydande grad på hur balansen mellan livs- och ekonomiska kvalitetsmåtten ser ut för medarbetarna.

  • 71.
    Aihara, Shin Ichi
    et al.
    Tokyo University of Science, Japan.
    Bagchi, Arunabha
    University of Twente, Enschede, Netherlands.
    Saha, Saikat
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Adaptive Filtering for Stochastic Volatility by Using Exact Sampling2013Ingår i: 10th International Conference on Informatics in Control, Automation and Robotics (ICINCO 2013), 2013, s. 326-335Konferensbidrag (Refereegranskat)
    Abstract [en]

    We study the sequential identification problem for Bates stochastic volatility model, which is widely used as the model of a stock in finance. By using the exact simulation method, a particle filter for estimating stochastic volatility is constructed. The systems parameters are sequentially estimated with the aid of parallel filtering algorithm. To improve the estimation performance for unknown parameters, the new resampling procedure is proposed. Simulation studies for checking the feasibility of the developed scheme are demonstrated.

  • 72.
    Aihara, ShinIchi
    et al.
    Tokyo University of Science, Japan.
    Bagch, Arunabha
    Twente University, Netherlands.
    Saha, Saikat
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Identification of Bates Stochastic Volatility Model by Using Non-Central Chi-Square Random Generation Method2012Ingår i: Proceedings of the 37th IEEE International Conference on Acoustics, Speech, and Signal Processing, 2012, , s. 4s. 3905-3908Konferensbidrag (Refereegranskat)
    Abstract [en]

    We study the identification problem for Bates stochastic volatility model, which is widely used as the model of a stock in finance. By using the exact simulation method, a particle filter for estimating stochastic volatility and its systems parameters is constructed. Simulation studies for checking the feasibility of the developed scheme are demonstrated.

  • 73.
    Aihara, ShinIchi
    et al.
    Tokyo University of Science Suwa, Japan.
    Bagchi, Arunabha
    University of Twente, Netherlands.
    Saha, Saikat
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska fakulteten.
    Filtering for Stochastic Volatility by Using Exact Sampling and Application to Term Structure Modeling2015Ingår i: INFORMATICS IN CONTROL, AUTOMATION AND ROBOTICS, Springer Science Business Media , 2015, Vol. 325, s. 329-348Konferensbidrag (Refereegranskat)
    Abstract [en]

    The Bates stochastic volatility model is widely used in the finance problem and the sequential parameter estimation problem becomes important. By using the exact simulation technique, a particle filter for estimating stochastic volatility is constructed. The system parameters are sequentially estimated with the aid of parallel filtering algorithm with the new resampling procedure. The proposed filtering procedure is also applied to the modeling of the term structure dynamics. Simulation studies for checking the feasibility of the developed scheme are demonstrated.

  • 74.
    Aili, Adam
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik.
    Ekelund, Erik
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik.
    Model-Based Design, Development and Control of an Underwater Vehicle2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    With the rising popularity of ROVs and other UV solutions, more robust and high performance controllers have become a necessity. A model of the ROV or UV can be a valuable tool during control synthesis. The main objective of this thesis was to use a model in design and development of controllers for an ROV.

    In this thesis, an ROV from Blue Robotics was used. The ROV was equipped with 6 thrusters placed such that the ROV was capable of moving in 6-DOFs. The ROV was further equipped with an IMU, two pressure sensors and a magnetometer. The ROV platform was further developed with EKF-based sensor fusion, a control system and manual control capabilities.

    To model the ROV, the framework of Fossen (2011) was used. The model was estimated using two different methods, the prediction-error method and an EKF-based method. Using the prediction-error method, it was found that the initial states of the quaternions had a large impact on the estimated parameters and the overall fit to validation data. A Kalman smoother was used to estimate the initial states. To circumvent the problems with the initial quaternions, an \abbrEKF was implemented to estimate the model parameters. The EKF estimator was less sensitive to deviations in the initial states and produced a better result than the prediction-error method. The resulting model was compared to validation data and described the angular velocities well with around 70 % fit.

    The estimated model was used to implement feedback linearisation which was used in conjunction with an attitude controller and an angular velocity controller. Furthermore, a depth controller was developed and tuned without the use of the model. Performance of the controllers was tested both in real tests and simulations. The angular velocity controller using feedback linearisation achieved good reference tracking. However, the attitude controller could not stabilise the system while using feedback linearisation. Both controllers' performance could be improved further by tuning the controllers' parameters during tests.

    The fact that the feedback linearisation made the ROV unstable, indicates that the attitude model is not good enough for use in feedback linearisation. To achieve stability, the magnitude of the parameters in the feedback linearisation were scaled down. The assumption that the ROV's center of rotation coincides with the placement of the ROV's center of gravity was presented as a possible source of error.

    In conclusion, good performance was achieved using the angular velocity controller. The ROV was easier to control with the angular velocity controller engaged compared to controlling it in open loop. More work is needed with the model to get acceptable performance from the attitude controller. Experiments to estimate the center of rotation and the center of gravity of the ROV may be helpful when further improving the model.

  • 75.
    Ainouz, Filip
    et al.
    Linköpings universitet, Institutionen för systemteknik.
    Vedholm, Jonas
    Linköpings universitet, Institutionen för systemteknik.
    Mean Value Model of the Gas Temperature at the Exhaust Valve2009Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Over the years many investigations of the gas temperature at the exhaust valve have been made. Nevertheless the modeling of the gas temperature still remains an unsolved problem. This master thesis approaches the problem by attempting to model the exhaust gas temperature by using the standard sensors equipped in SI engines, together with an in-cylinder pressure sensor which is needed in order to develop certain models. The concept in the master thesis is based upon a parameterization of the ideal Otto cycle with tuning parameters which all have physical meanings. Input variables required for the parameterization model is obtained from a fix point iteration method. This method was developed in order to improve the estimates of residual gas fraction, residual gas temperature and variables dependent of those, such as temperature at intake valve closing. The mean value model of the temperature, at the exhaust valve, is based upon the assumption of the ideal gas law, and that the burned gases undergoe a polytropic expansion into the exhaust manifold. Input variables to the entire model are intake manifold pressure, exhaust manifold pressure, intake manifold temperature, engine speed, air mass flow, cylinder pressure, air-to-fuel equivalence ratio, volume, and ignition timing. A useful aspect with modeling the exhaust gas temperature is the possibility to implement it in turbo modeling. By modeling the exhaust gas temperature the control of the turbo can be enhanced, due to the fact that energy is temperature dependent. Another useful aspect with the project is that the model can be utilized in diagnostics, to avoid hardware redundency in the creation of the desired residuals.

  • 76.
    Aizad, Noor
    Linköpings universitet, Institutionen för systemteknik.
    Design and implementation of comparator for sigma delta modulator2006Självständigt arbete på grundnivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats
    Abstract [en]

    Comparator is the main building block in an ADC architecture. Main purpose of the comparator is to compare a signal with a reference signal and produce an output depending on whether the input signal is greater or smaller than reference. Many architectures for comparators exist for various purposes. In this thesis, Latched comparator architecture is used for sigma delta modulator. This particular design has two main characteristics that are very important for sigma delta application. First characteristic is the cancellation of memory effect which increases the speed and reliability of the system and the second is, with this architecture, high sensitivity can be achieved.

    The design and implementation of lathed comparator for sigma delta modulator is presented in this thesis work. Various non-linearities and performance parameters are discussed in detail. Practical implementation and circuit design issues are highlighted to achieve maximum sensitivity along with reasonable speed and accuracy.

  • 77.
    Ajmal, Muhammad
    et al.
    Linköpings universitet, Institutionen för systemteknik, Informationskodning. Linköpings universitet, Tekniska högskolan.
    Zervas, Georgios
    High-Performance Networks Group, University of Bristol, UK.
    Saridis, George
    High-Performance Networks Group, University of Bristol, UK.
    Salas, Emilio H.
    High-Performance Networks Group, University of Bristol, UK.
    Simeonidou, Dimitra
    High-Performance Networks Group, University of Bristol, UK.
    Forchheimer, Robert
    Linköpings universitet, Institutionen för systemteknik, Informationskodning. Linköpings universitet, Tekniska högskolan.
    Flexible and Synthetic SDM Networks with Multi-core-Fibers Implemented by Programmable ROADMs2014Ingår i: Proceedings of European Conference on Optical Communication ECOC2014, Cannes, France, September 21-25 September 2014, IEEE , 2014, s. 1-3Konferensbidrag (Refereegranskat)
    Abstract [en]

    This study looks into network planning issues for synthetic MCF-based SDM networks implemented through programmable ROADMs. The results show that significant savings in switching modules and energy can be attained by exploiting the flexibility inherent in programmable ROADM through a proper network design.

  • 78.
    Ajmal, Muhammad
    et al.
    Linköpings universitet, Institutionen för systemteknik, Informationskodning. Linköpings universitet, Tekniska högskolan.
    Zervas, Georgios
    High-Performance Networks Group, University of Bristol, UK.
    Simeonidou, Dimitra
    High-Performance Networks Group, University of Bristol, UK.
    Forchheimer, Robert
    Linköpings universitet, Institutionen för systemteknik, Informationskodning. Linköpings universitet, Tekniska högskolan.
    Routing, Spectrum and Core Allocation in Flexgrid SDM Networks with Multi-core Fibers2014Ingår i: 2014 INTERNATIONAL CONFERENCE ON OPTICAL NETWORK DESIGN AND MODELING, IEEE , 2014, s. 192-197Konferensbidrag (Refereegranskat)
    Abstract [en]

    Space division multiplexing (SDM) over multi-core fiber (MCF) is advocated as a promising technology to overcome the capacity limit of the current single-core optical networks. However, employing the MCF for flexgrid networks necessitates the development of new concepts, such as routing, spectrum and core allocation (RSCA) for traffic demands. The introduction of MCF in the networks mitigates the spectrum continuity constraint of the routing and spectrum assignment (RSA) problem. In fact cores can be switched freely on different links during routing of the network traffic. Similarly, the route disjointness for demands with same allocated spectrum diminishes to core disjointness at the link level. On the other hand, some new issues such as the inter-core crosstalk should be taken into account while solving the RSCA problem. This paper formulates the RSCA network planning problem using the integer linear programming (ILP) formulation. The aim is to optimally minimize the maximum number of spectrum slices required on any core of MCF of a flexgrid SDM network. Furthermore, a scalable and effective heuristic is proposed for the same problem and its performance is compared with the optimal solution. The results show that the proposed algorithm is able to well approximate the optimal solution based on ILP model.

  • 79.
    Akhlaghpasand, Hossein
    et al.
    Iran Univ Sci and Technol, Iran.
    Razavizadeh, S. Mohammad
    Iran Univ Sci and Technol, Iran.
    Björnson, Emil
    Linköpings universitet, Institutionen för systemteknik, Kommunikationssystem. Linköpings universitet, Tekniska fakulteten.
    Do, Tan Tai
    Ericsson AB, Sweden.
    Jamming Detection in Massive MIMO Systems2018Ingår i: IEEE Wireless Communications Letters, ISSN 2162-2337, E-ISSN 2162-2345, Vol. 7, nr 2, s. 242-245Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This letter considers the physical layer security of a pilot-based massive multiple-input multiple-output (MaMIMO) system in presence of a multi-antenna jammer. We propose a new jamming detection method that makes use of a generalized likelihood ratio tes

  • 80.
    Akif, Ahmed
    Linköpings universitet, Institutionen för systemteknik, Datorteknik.
    FIR Filter Features on FPGA2018Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Finite-length impulse response (FIR) filters are one of the most commonly used digital signal processing algorithms used nowadays where a FPGA is the device used to implement it. The continued development of the FPGA device through the insertion of dedicated blocks raised the need to study the advantages offered by different FPGA families. The work presented in this thesis study the special features offered by FPGAs for FIR filters and introduce a cost model of resource utilization. The used method consist of several stages including reading, classification of features and generating coefficients. The results show that FPGAs have common features but also specific differences in features as well as resource utilization. It has been shown that there is misconception when dealing with FPGAs when it comes to FIR filter as compared to ASICs.

  • 81.
    Akin, Bilal
    et al.
    Texas Instruments Inc, USA.
    Choi, Seungdeog
    Texas A&M University, USA.
    Orguner, Umut
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Toliyat, Hamid A
    Texas A&M University, USA.
    A Simple Real-Time Fault Signature Monitoring Tool for Motor-Drive-Embedded Fault Diagnosis Systems2011Ingår i: IEEE transactions on industrial electronics (1982. Print), ISSN 0278-0046, E-ISSN 1557-9948, Vol. 58, nr 5, s. 1990-2001Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The reference frame theory constitutes an essential aspect of electric machine analysis and control. In this study, apart from the conventional applications, it is reported that the reference frame theory approach can successfully be applied to real-time fault diagnosis of electric machinery systems as a powerful toolbox to find the magnitude and phase quantities of fault signatures with good precision as well. The basic idea is to convert the associated fault signature to a dc quantity, followed by the computation of the signals average in the fault reference frame to filter out the rest of the signal harmonics, i.e., its ac components. As a natural consequence of this, neither a notch filter nor a low-pass filter is required to eliminate fundamental component or noise content. Since the incipient fault mechanisms have been studied for a long time, the motor fault signature frequencies and fault models are very well-known. Therefore, ignoring all other components, the proposed method focuses only on certain fault signatures in the current spectrum depending on the examined motor fault. Broken rotor bar and eccentricity faults are experimentally tested online using a TMS320F2812 digital signal processor (DSP) to prove the effectiveness of the proposed method. In this application, only the readily available drive hardware is used without employing additional components such as analog filters, signal conditioning board, external sensors, etc. As the motor drive processing unit, the DSP is utilized both for motor control and fault detection purposes, providing instantaneous fault information. The proposed algorithm processes the measured data in real time to avoid buffering and large-size memory needed in order to enhance the practicability of this method. Due to the short-time convergence capability of the algorithm, the fault status is updated in each second. The immunity of the algorithm against non-ideal cases such as measurement offset errors and phase unbalance is theoretically and experimentally verified. Being a model-independent fault analyzer, this method can be applied to all multiphase and single-phase motors.

  • 82.
    Akram, Awais
    et al.
    Linköpings universitet, Institutionen för teknik och naturvetenskap.
    Ahmad, Hamad
    Linköpings universitet, Institutionen för teknik och naturvetenskap.
    Potential of existing UMTS Signaling Data for Cell Phone Positioning2011Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In the current era of telecommunication the usage of cellular network has increased rapidly. Number of different new services are introduced i.e. navigation, friend finder, internet browsing, nearby filling stations, shopping centers, traffic information and emergency services. Most of these services are location based and needs the information of particular area to provide the exact services.

    The addition of location based services in 3G network opens the new ways of using Mobile devices due to which cellular networks has faced number of challenges in providing better positioning accuracy which is the main requirement for location based services. To bear these challenges everyday new ways of finding the accurate position are introduced but most them required upgraded networks or highly equipped terminal.

    In this thesis the purpose is to find the potential in UMTS signaling data to estimate the position of the user equipment as accurate as possible using the legacy terminals. In this thesis SFN-SFN observed time difference is explored and used in Database Correlation Method (DCM) in network based positioning. This thesis is done by first analyzing the RSCP for the particular area to verify the conditions of FCC. The data is collected in real environment through test drive using TEMS investigation tool and the available measurement reports from the terminal are used to design and implement the DCM Algorithm. Two new approaches are introduced in this thesis SFN-SFN OTD and Hybrid. In Hybrid RSCP and SFN-SFN OTD are used together.

    In conclusion, the final results from the performed experiments show improvement in estimated position accuracy by Hybrid technique which is a new step in finding the position of user equipment by DCM.

  • 83.
    Akçay, Hüseyin
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Hjalmarsson, Håkan
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    The Least-Squares Identification of FIR Systems Subject to Worst-Case Noise1993Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The least-squares identification of FIR systems is analyzed assuming that the noise is a bounded signal and the input signal is a pseudo-random binary sequence. A lower bound on the worst-case transfer function error shows that the lest-square estimate of the transfer function diverges as the order of the FIR system is increased. This implies that, in the presence of the worst-case noise, the trade-off between the estimation error due to the disturbance and the bias error (due to unmodeled dynamics) is significantly different from the corresponding trade-off in the random error case: with a worst-case formulation, the model complexity should not increase indefinitely as the size of the data set increases.

  • 84.
    Akçay, Hüseyin
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Hjalmarsson, Håkan
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    The Least-Squares Identification of FIR Systems Subject to Worst-Case Noise1994Ingår i: Proceedings of the 10th IFAC Symposium on System Identification, 1994, Vol. 2, s. 85-90Konferensbidrag (Refereegranskat)
    Abstract [en]

    The least-squares identification of FIR systems is analyzed assuming that the noise is a bounded signal and the input signal is a pseudo-random binary sequence. A lower bound on the worst-case transfer function error shows that the lest-square estimate of the transfer function diverges as the order of the FIR system is increased. This implies that, in the presence of the worst-case noise, the trade-off between the estimation error due to the disturbance and the bias error (due to unmodeled dynamics) is significantly different from the corresponding trade-off in the random error case: with a worst-case formulation, the model complexity should not increase indefinitely as the size of the data set increases.

  • 85.
    Akçay, Hüseyin
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Hjalmarsson, Håkan
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    The Least-Squares Identification of FIR Systems Subject to Worst-Case Noise1994Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The least-squares identification of FIR systems is analyzed assuming that the noise is a bounded signal and the input signal is a pseudo-random binary sequence. A lower bound on the worst-case transfer function error shows that the least-square estimate of the transfer function diverges as the order of the FIR system is increased. This implies that, in the presence of the worst-case noise, the trade-off between the estimation error due to the disturbance and the bias error (due to unmodeled dynamics) is significantly different from the corresponding trade-off in the random error case: with a worst-case formulation, the model complexity should not increase indefinitely as the size of the data set increases.

  • 86.
    Akçay, Hüseyin
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Hjalmarsson, Håkan
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    The Least-Squares Identification of FIR Systems Subject to Worst-Case Noise1994Ingår i: Systems & control letters (Print), ISSN 0167-6911, E-ISSN 1872-7956, Vol. 23, nr 5, s. 329-338Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The least-squares identification of FIR systems is analyzed assuming that the noise is a bounded signal and the input signal is a pseudo-random binary sequence. A lower bound on the worst-case transfer function error shows that the least-square estimate of the transfer function diverges as the order of the FIR system is increased. This implies that, in the presence of the worst-case noise, the trade-off between the estimation error due to the disturbance and the bias error (due to unmodeled dynamics) is significantly different from the corresponding trade-off in the random error case: with a worst-case formulation, the model complexity should not increase indefinitely as the size of the data set increases.

  • 87.
    Akçay, Hüseyin
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Hjalmarsson, Håkan
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Ljung, Lennart
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    On the Choice of Norms in System Identification1994Ingår i: Proceedings of the 10th IFAC Symposium on System Identification, 1994, Vol. 2, s. 103-108Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we discuss smooth and sensitive norms for prediction error system identification when the disturbances are magnitude bounded. Formal conditions for sensitive norms, which give an order of magnitude faster convergence of the parameter estimate variance, are developed. However, it also is shown that the parameter estimate variance convergence rate of sensitive norms is arbitrarily bad for certain distributions. A necessary condition for a norm to be statistically robust with respect to the family F(C) of distributions with support [-C, C] for some arbitrary C>0 is that its second derivative does not vanish on the support. A direct consequence of this observation is that the quadratic norm is statistically robust among all lp-norms, p⩽2<∞ for F(C).

  • 88.
    Akçay, Hüseyin
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Hjalmarsson, Håkan
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Ljung, Lennart
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    On the Choice of Norms in System Identification1994Rapport (Övrigt vetenskapligt)
    Abstract [en]

    In this paper we discuss smooth and sensitive norms for prediction error system identification when the disturbances are magnitude bounded. Formal conditions for sensitive norms, which give an order of magnitude faster convergence of the parameter estimate variance, are developed. However, it also is shown that the parameter estimate variance convergence rate of sensitive norms is arbitrarily bad for certain distributions. A necessary condition for a norm to be statistically robust with respect to the family F(C) of distributions with support [-C, C] for some arbitrary C>0 is that its second derivative does not vanish on the support. A direct consequence of this observation is that the quadratic norm is statistically robust among all lp-norms, p⩽2<∞ for F(C).

  • 89.
    Akçay, Hüseyin
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Hjalmarsson, Håkan
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Ljung, Lennart
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    On the Choice of Norms in System Identification1996Rapport (Övrigt vetenskapligt)
    Abstract [en]

    In this paper we discuss smooth and sensitive norms for prediction error system identification when the disturbances are magnitude bounded. Formal conditions for sensitive norms, which give an order of magnitude faster convergence of the parameter estimate variance, are developed. However, it also is shown that the parameter estimate variance convergence rate of sensitive norms is arbitrarily bad for certain distributions. A necessary condition for a norm to be statistically robust with respect to the family F(C) of distributions with support [-C, C] for some arbitrary C>0 is that its second derivative does not vanish on the support. A direct consequence of this observation is that the quadratic norm is statistically robust among all lp-norms, p⩽2<∞ for F(C).

  • 90.
    Akçay, Hüseyin
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Ljung, Lennart
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Hjalmarsson, Håkan
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    On the Choice of Norms in System Identification1994Rapport (Övrigt vetenskapligt)
    Abstract [en]

    In this paper we discuss smooth and sensitive norms for prediction error system identification when the disturbances are magnitude bounded. Formal conditions for sensitive norms, which give an order of magnitude faster convergence of the parameter estimate variance, are developed. However, it also is shown that the parameter estimate variance convergence rate of sensitive norms is arbitrarily bad for certain distributions. A necessary condition for a norm to be statistically robust with respect to the family F(C) of distributions with support [-C, C] for some arbitrary C>0 is that its second derivative does not vanish on the support. A direct consequence of this observation is that the quadratic norm is statistically robust among all lp-norms, p⩽2<∞ for F(C).

  • 91.
    Al Faisal, Muhammad Saud
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska högskolan.
    6-9 GHz UWB Antenna-Low-Noise Amplifier Co-design2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    6 - 9 GHz antenna-low-noise amplifier co-design is a demanding task. Higher frequency band has new techniques for circuit design and matching. The usual lumped component matching technique is not an appropriate solution for High Frequency (HF) broad band. The new broad band demands transmission line matching. The low-power and high-data rate Ultra Wide Band (UWB) uses large portion of the communication radio-spectrum and wireless communication. The principal axis of this thesis is co-design in the frequency band of 6 - 9 GHz. The thesis has been divided in two parts, where first part includes implementation and evaluation of individual RF-circuits of circular monopole antenna, a band pass (BP) filter and a low-noise amplifier (LNA), while second part unite all three RF circuits and presents the co-design.

    Microstrip monopole antennas get more and more popular due to rapid change in the wireless communication. Higher datarate and even higher bandwidth demands a simple and compact ultra-wideband (UWB) antenna. Two monopole antennas circular and rectangular monopole antennas were designed. Simulated and experimental results of modified design indicate that antenna was achieved a VSWR of 1.2, with input reflection less then - 10 dB in 4 - 12 GHz band. These characteristic make the designed antenna suitable for various UWB application.

     The broad band matching and the flat gain are the two important factors for the UWB circuits. The co-design of antenna-low-noise amplifier utilizes a inter stage matching technique with a simple band pass filter, a third-order passive Chebychev filter is proposed as an input matching network. The filter achieves forward transmission less the - 0.8 dB and a return loss - 20 dB in 6 - 9 GHz band.

    Low-noise amplifier is the key RF circuit; minimal Noise Figure (NF) and the lower power consumption are desired parameters. The implemented low-noise amplifier (LNA) is the combination of bias network and ultra-wide band radio frequency (RF) choke. AVAGO Technologies pseudmorphic-high-electron-mobility transistor (PHEMT) with (SC-70) plastic package with nominal 0.2 µm gate length is used in amplifier. Passive distributed components of microstrip transmission line were used for matching, simulated results demonstrate maximum power gain of 12.74 dB and minimum noise figure (NFmin) of 1 dB is obtained.

    Finally all three individual RF circuits antenna, filter and low-noise amplifier are integrated into co-design and analyzed for 6 - 9 GHz band. Later on two more new designs are added. This co-design has large potential in Direct-broadcast-satellite (DBS) TV system, X-band radar detector, automotive radar, remote sensors, and Multichannel-multipoint-distribution-systems (MMDS). 

  • 92.
    Al Kadi Jazairli, Mohamad
    Linköpings universitet, Institutionen för teknik och naturvetenskap.
    Growth of Zinc Oxide Nanoparticles on Top of Polymers and Organic Small Molecules as a Transparent Cathode in Tandem Photovoltaic Device2008Självständigt arbete på grundnivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats
    Abstract [en]

    Organic solar cells have caught considerable attention in the past few years due to their potential for providing environmentally safe, flexible, lightweight, inexpensive, and roll-to-roll feasible production solar cells. However, the efficiency achieved in current organic solar cells is quite low, yet quick and successive improvements render it as a promising alternative. A hopeful approach to improve the efficiency is by exploiting the tandem concept which consists of stacking two or more organic solar cells in series.

    One important constituent in tandem solar cells is the middle electrode layer which is transparent and functions as a cathode for the first cell and an anode for the second cell. Most studies done so far have employed noble metals such as gold or silver as the middle electrode layer; however, they suffered from several shortcomings especially with respect to reproducibility.

    This thesis focuses on studying a new trend which employs an oxide material based on nano-particles as a transparent cathode (such as Zinc-oxide-nano-particles) along with a transparent anode so as to replace the middle electrode.

    Thus, this work presents a study on solution processable zinc oxide (ZnO) nanostructures, their proper handling techniques, and their potential as a middle electrode material in Tandem solar cells in many different configurations involving both polymer and small molecule materials. Moreover, the ZnO-np potential as a candidate for acceptor material is also investigated.

  • 93.
    Alam, Syed Asad
    Linköpings universitet, Institutionen för systemteknik.
    Design Space Exploration of Time-Multiplexed FIRFilters on FPGAs2010Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    FIR (Finite-length Impulse Response) filters are the corner stone of many signalprocessing devices. A lot of research has gone into their development as wellas their effective implementation. With recent research focusing a lot on powerconsumption reduction specially with regards to FPGAs, it was found necessaryto explore FIR filters mapping on FPGAs.

    Time multiplexed FIR filters are also a good candidate for examination withrespect to power consumption and resource utilization, for example when implementedin Field Programmable Gate Arrays (FPGAs). This is motivated by thefact that the usable clock frequency often is higher compared to the required datarate. Current implementations by, e.g., Xilinx FIR Compiler suffer from highpower consumption when the time multiplexing factor is low. Further, it needs tobe investigated how exploiting coefficient symmetry, scaling the coefficients andincreasing the time-multiplexing factor influences the performance.

  • 94.
    Alam, Syed Asad
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska fakulteten.
    Techniques for Efficient Implementation of FIR and Particle Filtering2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    FIR filters occupy a central place many signal processing applications which either alter the shape, frequency or the sampling frequency of the signal. FIR filters are used because of their stability and possibility to have linear-phase but require a high filter order to achieve the same magnitude specifications as compared to IIR filters. Depending on the size of the required transition bandwidth the filter order can range from tens to hundreds to even thousands. Since the implementation of the filters in digital domain requires multipliers and adders, high filter orders translate to a large number of these arithmetic units for its implementation. Research towards reducing the complexity of FIR filters has been going on for decades and the techniques used can be roughly divided into two categories; reduction in the number of multipliers and simplification of the multiplier implementation. 

    One technique to reduce the number of multipliers is to use cascaded sub-filters with lower complexity to achieve the desired specification, known as FRM. One of the sub-filters is a upsampled model filter whose band edges are an integer multiple, termed as the period L, of the target filter's band edges. Other sub-filters may include complement and masking filters which filter different parts of the spectrum to achieve the desired response. From an implementation point-of-view, time-multiplexing is beneficial because generally the allowable maximum clock frequency supported by the current state-of-the-art semiconductor technology does not correspond to the application bound sample rate. A combination of these two techniques plays a significant role towards efficient implementation of FIR filters. Part of the work presented in this dissertation is architectures for time-multiplexed FRM filters that benefit from the inherent sparsity of the periodic model filters.

    These time-multiplexed FRM filters not only reduce the number of multipliers but lowers the memory usage. Although the FRM technique requires a higher number delay elements, it results in fewer memories and more energy efficient memory schemes when time-multiplexed. Different memory arrangements and memory access schemes have also been discussed and compared in terms of their efficiency when using both single and dual-port memories. An efficient pipelining scheme has been proposed which reduces the number of pipelining registers while achieving similar clock frequencies. The single optimal point where the number of multiplications is minimum for non-time-multiplexed FRM filters is shown to become a function of both the period, L and time-multiplexing factor, M. This means that the minimum number of multipliers does not always correspond to the minimum number of multiplications which also increases the flexibility of implementation. These filters are shown to achieve power reduction between 23% and 68% for the considered examples.

    To simplify the multiplier, alternate number systems like the LNS have been used to implement FIR filters, which reduces the multiplications to additions. FIR filters are realized by directly designing them using ILP in the LNS domain in the minimax sense using finite word length constraints. The branch and bound algorithm, a typical algorithm to implement ILP problems, is implemented based on LNS integers and several branching strategies are proposed and evaluated. The filter coefficients thus obtained are compared with the traditional finite word length coefficients obtained in the linear domain. It is shown that LNS FIR filters provide a better approximation  error compared to a standard FIR filter for a given coefficient word length.

    FIR filters also offer an opportunity in complexity reduction by implementing the multipliers using Booth or standard high-radix multiplication. Both of these multiplication schemes generate pre-computed multiples of the multiplicand which are then selected based on the encoded bits of the multiplier. In TDF FIR filters, one input data is multiplied with a number of coefficients and complexity can be reduced by sharing the pre-computation of the multiplies of the input data for all multiplications. Part of this work includes a systematic and unified approach to the design of such computation sharing multipliers and a comparison of the two forms of multiplication. It also gives closed form expressions for the cost of different parts of multiplication and gives an overview of various ways to implement the select unit with respect to the design of multiplexers.

    Particle filters are used to solve problems that require estimation of a system. Improved resampling schemes for reducing the latency of the resampling stage is proposed which uses a pre-fetch technique to reduce the latency between 50% to 95%  dependent on the number of pre-fetches. Generalized division-free architectures and compact memory structures are also proposed that map to different resampling algorithms and also help in reducing the complexity of the multinomial resampling algorithm and reduce the number of memories required by up to 50%.

    Delarbeten
    1. A unified approach to the design and implementation of computation sharing multipliers: Computation sharing multipliers
    Öppna denna publikation i ny flik eller fönster >>A unified approach to the design and implementation of computation sharing multipliers: Computation sharing multipliers
    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    A unified approach to the design and implementation of computation sharing multiplier based on Booth and standard high-radix multiplication schemes is presented here. Both of these multiplication schemes have various building blocks and one of which is the pre-computer which can be shared across a number of multiplications if the multiplicand to the multipliers is same, like in a transposed direct form (TDF) finitelength impulse response (FIR) filter. Closed form expressions to estimate the cost of different building blocks based on different schemes have been developed and analyzed in different dimensions. Standalone multipliers and as part of computation sharing in FIR filters and complex multipliers have been realized in hardware and synthesized using standard cell library.

    It is shown that apart from word length and filter length, the ratio  between the cost of implementing adders and multiplexers has an effect on the choice of optimal radix. The higher the ratio, the lower is the cost of implementing multiplexers which will benefit high radix. Higher radix will also benefit from computation sharing if the cost of one multiplication for it is less than the lower radix and it is shown that radix-16 Booth multiplier achieves lower area complexity and power consumption by an average of 7% and 17%, respectively.

    Nyckelord
    Computation sharing multipliers, standard high-radix multiplier, Booth multiplier, FIR filter
    Nationell ämneskategori
    Elektroteknik och elektronik
    Identifikatorer
    urn:nbn:se:liu:diva-124194 (URN)
    Tillgänglig från: 2016-01-21 Skapad: 2016-01-21 Senast uppdaterad: 2016-02-02Bibliografiskt granskad
    2. On the implementation of time-multiplexed frequency-response masking filters
    Öppna denna publikation i ny flik eller fönster >>On the implementation of time-multiplexed frequency-response masking filters
    2016 (Engelska)Ingår i: IEEE Transactions on Signal Processing, ISSN 1053-587X, E-ISSN 1941-0476, Vol. 64, nr 15, s. 3933-3944Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    The complexity of narrow transition band finite-length impulse response (FIR) filters is high and can be reduced by using frequency-response masking (FRM) techniques. These techniques use a combination of periodic model and, possibly periodic, masking filters. Time-multiplexing is in general beneficial since only rarely does the technology bound maximum obtainable clock frequency and the application determined required sample rate correspond. Therefore, architectures for time-multiplexed FRM filters that benefit from the inherent sparsity of theperiodic filters are introduced in this work.

    We show that FRM filters not only reduces the number of multipliers needed, but also have benefits in terms of memory usage. Despite the total amount of samples to be stored is larger for FRM, it results in fewer memory resources needed in FPGAs and more energy efficient memory schemes in ASICs. In total, the power consumption is significantly reduced compared to a single stage implementation. Furthermore, we show that the choice of the interpolation factor which gives the least complexity for the periodic model filter and subsequent masking filter(s) is a function of the time-multiplexing factor, meaning that the minimum number of multipliers not always correspond to the minimum number of multiplications. Both single-port and dual-port memories are considered and the involved trade-off in number of multipliers and memory complexity is illustrated. The results show that for FPGA implementation, the power reduction ranges from 23% to 68% for the considered examples.

    Ort, förlag, år, upplaga, sidor
    Institute of Electrical and Electronics Engineers (IEEE), 2016
    Nyckelord
    Frequency-response masking, FIR filter, FPGA, ASIC, time-multiplexing, memories
    Nationell ämneskategori
    Elektroteknik och elektronik
    Identifikatorer
    urn:nbn:se:liu:diva-124190 (URN)10.1109/TSP.2016.2557298 (DOI)000379699800009 ()
    Anmärkning

    Vid tiden för disputation förelåg publikationen som manuskript

    Tillgänglig från: 2016-01-21 Skapad: 2016-01-21 Senast uppdaterad: 2017-11-30Bibliografiskt granskad
    3. Design of Finite Word Length Linear-Phase FIR Filters inthe Logarithmic Number System Domain
    Öppna denna publikation i ny flik eller fönster >>Design of Finite Word Length Linear-Phase FIR Filters inthe Logarithmic Number System Domain
    2014 (Engelska)Ingår i: VLSI design (Print), ISSN 1065-514X, E-ISSN 1563-5171, Vol. 2014, nr 217495Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Logarithmic number system (LNS) is an attractive alternative to realize finite-length impulse response filters because ofmultiplication in the linear domain being only addition in the logarithmic domain. In the literature, linear coefficients are directlyreplaced by the logarithmic equivalent. In this paper, an approach to directly optimize the finite word length coefficients in theLNS domain is proposed. This branch and bound algorithm is implemented based on LNS integers and several different branchingstrategies are proposed and evaluated. Optimal coefficients in the minimax sense are obtained and compared with the traditionalfinite word length representation in the linear domain as well as using rounding. Results show that the proposed method naturallyprovides smaller approximation error compared to rounding. Furthermore, they provide insights into finite word length propertiesof FIR filters coefficients in the LNS domain and show that LNS FIR filters typically provide a better approximation error comparedto a standard FIR filter.

    Ort, förlag, år, upplaga, sidor
    Egypt: Hindawi Publishing Corporation, 2014
    Nyckelord
    Logarithmic Number System, FIR Filter, Integer Linear Programming, Branch and Bound
    Nationell ämneskategori
    Signalbehandling
    Identifikatorer
    urn:nbn:se:liu:diva-105861 (URN)10.1155/2014/217495 (DOI)
    Tillgänglig från: 2014-04-10 Skapad: 2014-04-10 Senast uppdaterad: 2017-12-05Bibliografiskt granskad
    4. Improved particle filter resampling architectures
    Öppna denna publikation i ny flik eller fönster >>Improved particle filter resampling architectures
    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The most challenging aspect of particle filtering hardware implementation is the resampling step which replicates particles with large weights and discards those with small weights because it has a high latency and can only be partially executed in parallel with the other steps of particle filtering. To reduce the latency, an improved resampling scheme is proposed in this work which involves pre-fetching from the weight memory in parallel to the fetching of a value from a random function generator. Architectures for realizing the pre-fetch technique are also proposed. The trade-off between the latency reduction achieved by increasing the size of the pre-fetch memory and the architectural implementation complexity has been analyzed. Results show that a pre-fetch of five achieves the best area-latency trade-off while on average achieving an 85% reduction in the latency.

    We also propose a generic double multiplier architecture for resampling which avoids normalization divisions and makes the architecture equally efficient for non-powers-of-two number of particles as well as removes the need of explicitly ordering the random values for efficient multinomial resampling implementation. It is further improved by computing the cumulative sum of weights on-the-fly which helps in reducing the size of the weight memories by up to 50%.

    Nyckelord
    Particle filters, resampling algorithm, resampling architecture
    Nationell ämneskategori
    Elektroteknik och elektronik
    Identifikatorer
    urn:nbn:se:liu:diva-124193 (URN)
    Tillgänglig från: 2016-01-21 Skapad: 2016-01-21 Senast uppdaterad: 2016-02-02Bibliografiskt granskad
  • 95.
    Alam, Syed Asad
    et al.
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska fakulteten.
    Gustafsson, Oscar
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska fakulteten.
    A unified approach to the design and implementation of computation sharing multipliers: Computation sharing multipliersManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    A unified approach to the design and implementation of computation sharing multiplier based on Booth and standard high-radix multiplication schemes is presented here. Both of these multiplication schemes have various building blocks and one of which is the pre-computer which can be shared across a number of multiplications if the multiplicand to the multipliers is same, like in a transposed direct form (TDF) finitelength impulse response (FIR) filter. Closed form expressions to estimate the cost of different building blocks based on different schemes have been developed and analyzed in different dimensions. Standalone multipliers and as part of computation sharing in FIR filters and complex multipliers have been realized in hardware and synthesized using standard cell library.

    It is shown that apart from word length and filter length, the ratio  between the cost of implementing adders and multiplexers has an effect on the choice of optimal radix. The higher the ratio, the lower is the cost of implementing multiplexers which will benefit high radix. Higher radix will also benefit from computation sharing if the cost of one multiplication for it is less than the lower radix and it is shown that radix-16 Booth multiplier achieves lower area complexity and power consumption by an average of 7% and 17%, respectively.

  • 96.
    Alam, Syed Asad
    et al.
    Linköpings universitet, Institutionen för systemteknik, Elektroniksystem. Linköpings universitet, Tekniska högskolan.
    Gustafsson, Oscar
    Linköpings universitet, Institutionen för systemteknik, Elektroniksystem. Linköpings universitet, Tekniska högskolan.
    Design of Finite Word Length Linear-Phase FIR Filters inthe Logarithmic Number System Domain2014Ingår i: VLSI design (Print), ISSN 1065-514X, E-ISSN 1563-5171, Vol. 2014, nr 217495Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Logarithmic number system (LNS) is an attractive alternative to realize finite-length impulse response filters because ofmultiplication in the linear domain being only addition in the logarithmic domain. In the literature, linear coefficients are directlyreplaced by the logarithmic equivalent. In this paper, an approach to directly optimize the finite word length coefficients in theLNS domain is proposed. This branch and bound algorithm is implemented based on LNS integers and several different branchingstrategies are proposed and evaluated. Optimal coefficients in the minimax sense are obtained and compared with the traditionalfinite word length representation in the linear domain as well as using rounding. Results show that the proposed method naturallyprovides smaller approximation error compared to rounding. Furthermore, they provide insights into finite word length propertiesof FIR filters coefficients in the LNS domain and show that LNS FIR filters typically provide a better approximation error comparedto a standard FIR filter.

  • 97.
    Alam, Syed Asad
    et al.
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska fakulteten.
    Gustafsson, Oscar
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska fakulteten.
    Generalized Division-Free Architecture and Compact Memory Structure for Resampling in Particle Filters2015Ingår i: 2015 European Conference on Circuit Theory and Design (ECCTD), IEEE Press, 2015, s. 416-419Konferensbidrag (Refereegranskat)
    Abstract [en]

    The most challenging step of implementing particle filtering is the resampling step which replicates particles with large weights and discards those with small weights. In this paper, we propose a generic architecture for resampling which uses double multipliers to avoid normalization divisions and make the architecture  equally efficient for non-powers-of-two number of particles. Furthermore, the complexity of resampling is greatly affected by the size of memories used to store weights. We illustrate that by storing the original weights instead of their cumulative sum and calculating them online reduces the total complexity, in terms of area, ranging from 21% to 45%, while giving up to 50% reduction in memory usage.

  • 98.
    Alam, Syed Asad
    et al.
    Linköpings universitet, Institutionen för systemteknik, Elektroniksystem. Linköpings universitet, Tekniska högskolan.
    Gustafsson, Oscar
    Linköpings universitet, Institutionen för systemteknik, Elektroniksystem. Linköpings universitet, Tekniska högskolan.
    Implementation of Narrow-Band Frequency-Response Masking for Efficient Narrow Transition Band FIR Filters on FPGAs2011Ingår i: NORCHIP, 2011, IEEE conference proceedings, 2011, s. 1-4Konferensbidrag (Refereegranskat)
    Abstract [en]

    The complexity of narrow transition band FIR filters is highand can be reduced by using frequency response masking (FRM) techniques. Thesetechniques use a combination of periodic model filters and masking filters. Inthis paper, we show that time-multiplexed FRM filters achieve lowercomplexity, not only in terms of multipliers, but also logic elements compared to time-multiplexed singlestage filters. The reduced complexity also leads to a lower power consumption. Furthermore, we show that theoptimal period of the model filter is dependent on the time-multiplexing factor.

  • 99.
    Alam, Syed Asad
    et al.
    Linköpings universitet, Institutionen för systemteknik, Elektroniksystem. Linköpings universitet, Tekniska högskolan.
    Gustafsson, Oscar
    Linköpings universitet, Institutionen för systemteknik, Elektroniksystem. Linköpings universitet, Tekniska högskolan.
    Implementation of Time-Multiplexed Sparse Periodic FIR Filters for FRM on FPGAs2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    Frequency-response masking (FRM) is a set of techniques for lowering the computational complexity of narrow transition band FIR filters. These FRM use a combination of sparse periodic filters and non-sparse filters. In this work we consider the implementation of these filters in a time-multiplexed manner on FPGAs. It is shown that the proposed architectures produce lower complexity realizations compared to the vendor provided IP blocks, which do not take the sparseness into consideration. The designs are implemented on a Virtex-6 device utilizing the built-in DSP blocks.

  • 100.
    Alam, Syed Asad
    et al.
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska fakulteten.
    Gustafsson, Oscar
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska fakulteten.
    Improved particle filter resampling architecturesManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The most challenging aspect of particle filtering hardware implementation is the resampling step which replicates particles with large weights and discards those with small weights because it has a high latency and can only be partially executed in parallel with the other steps of particle filtering. To reduce the latency, an improved resampling scheme is proposed in this work which involves pre-fetching from the weight memory in parallel to the fetching of a value from a random function generator. Architectures for realizing the pre-fetch technique are also proposed. The trade-off between the latency reduction achieved by increasing the size of the pre-fetch memory and the architectural implementation complexity has been analyzed. Results show that a pre-fetch of five achieves the best area-latency trade-off while on average achieving an 85% reduction in the latency.

    We also propose a generic double multiplier architecture for resampling which avoids normalization divisions and makes the architecture equally efficient for non-powers-of-two number of particles as well as removes the need of explicitly ordering the random values for efficient multinomial resampling implementation. It is further improved by computing the cumulative sum of weights on-the-fly which helps in reducing the size of the weight memories by up to 50%.

1234567 51 - 100 av 7491
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf