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  • 101. Berggren, Magnus
    et al.
    Stjernberg, Louise
    Lindström, Fredric
    Claesson, Ingvar
    Audio Processing Solution for Video Conference Based Aerobics2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper an audio processing solution for video conference based aerobics is presented. The proposed solution leaves the workout music unaltered by separating it from the speech and processing each signal separately. The speech signal processing is also performed at a lower sample rate, which saves computational power. Real time evaluation of the system shows that high quality music as well as a good two-way communication is maintained during the aerobic session.

  • 102.
    Betschart, Willie
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling.
    Applying intelligent statistical methods on biometric systems2005Självständigt arbete på avancerad nivå (magisterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    This master’s thesis work was performed at Optimum Biometric Labs, OBL, located in Karlskrona, Sweden. Optimum Biometric Labs perform independent scenario evaluations to companies who develop biometric devices. The company has a product Optimum preConTM which is surveillance and diagnosis tool for biometric systems. This thesis work’s objective was to develop a conceptual model and implement it as an additional layer above the biometric layer with intelligence about the biometric users. The layer is influenced by the general procedure of biometrics in a multimodal behavioural way. It is working in an unsupervised way and performs in an unsupervised manner. While biometric systems are increasingly adopted the technologies have some inherent problems such as false match and false non-match. In practice, a rejected user can not be interpreted as an impostor since the user simply might have problems using his/her biometric feature. The proposed methods in this project are dealing with these problems when analysing biometric usage in runtime. Another fact which may give rise to false rejections is template aging; a phenomenon where the enrolled user’s template is too old compared towards the user’s current biometric feature. A theoretical approach of template aging was known; however since the analysis of template aging detection was correlated with potential system flaws such as device defects or human generated risks such as impostor attacks this task would become difficult to solve in an unsupervised system but when ignoring the definition of template aging, the detection of similar effects was possible. One of the objectives of this project was to detect template aging in a predictive sense; this task failed to be carried out because the absence of basis performing this kind of tasks. The developed program performs abnormality detection at each incoming event from a biometric system. Each verification attempt is assumed to be from a genuine user unless any deviation according to the user's history is found, an abnormality. The possibility of an impostor attack depends on the degree of the abnormality. The application makes relative decisions between fraud possibilities or if genuine user was the source of what caused the deviations. This is presented as an alarm with the degree of impostor possibility. This intelligent layer has increased Optimum preCon´s capacity as a surveillance tool for biometrics. This product is an efficient complement to biometric systems in a steady up-going worldwide market.

  • 103.
    Bhuiyan, Raisul Haque Masud
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling. Ericsson AB. Åbo Akademi University..
    LOW DELAY VIDEO TRANSCODING SERVICES ON DISTRUBUTED COMPUTING PLATFORM.2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The demand of digital video with higher resolution is increasing everyday and in amodern world the videos are consumed in all kinds of multimedia devices. The transmissionof higher quality videos over the internet require higher bandwidth, which isnot an acceptable option. So, it is necessary to compress the video to a compact file byremoving redundancies and detail information.

    The process of compressing a video file requires a lot of complex calculations,which is a time consuming process, specially for live telecasting or real-time videoconferencing. In addition videos with higher quality such as higher number of Frameper Second (FPS) or higher resolution like HD and 4k video requires huge redundantdata processing. Hence, this operation causes delays during the video playback. Tominimize the time delay for the video coding, there are coding methods such as losslessand lossy coding which has been around for a long time. However, the idea to increasethe number of processing unit like CPUs and memory for video coding software is anarea that require further research to improve coding techniques.

    Distributed system uses available resources in the network to achieve a commongoal. It explores the available infrastructure so that the task can be done in parallel. Cloud computing is a great example of distributed system which has fully dedicatedresources for such complex jobs.

    This thesis deals with these areas in real-time to lower the video coding delaythrough investigating distributed resources as well as the parallelization in video codingstandards such as AVC and HEVC. It has been carried out with a collaborationwith Ericsson Research in Stockholm.

  • 104.
    Bhutto, Tarique Inayat
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap.
    Root LDPC Codes for Non Ergodic Transmission Channels2011Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    4 ABSTRACT Tremendous amount of research has been conducted in modern coding theory in the past few years and much of the work has been done in developing new coding techniques. Low density parity check (LDPC) codes are class of linear block error correcting codes which provide capacity performance on a large collection of data transmission and storage channels while Root LDPC codes in this thesis work are admitting implementable decoders with manageable complexity. Furthermore, work has been conducted to develop graphical methods to represent LDPC codes. This thesis implement one of the LDPC kind “Root LDPC code” using iterative method and calculate its threshold level for binary and non-binary Root LDPC code. This threshold value can serve as a starting point for further study on this topic. We use C++ as tool to simulate the code structure and parameters. The results show that non-binary Root LDPC code provides higher threshold value as compare to binary Root LDPC code.

  • 105.
    Biswas, Md Abdul Matin
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap.
    Exploiting the Direct Communication Link for Enhancing Effective Capacity Performance of Cognitive Radio Relay Networks2014Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    Nowadays, cognitive radio (CR) is a promising concept to improve the radio spectrum exploitation. CR has tremendous ability to enhance spectrum efficiency by allowing secondary users (SUs) to access licensed radio spectrum resource which is currently not being used by primary users (PUs). One basic challenge of that paradigm is securing the quality of service (QoS) of the primary link transmission while increasing the rate of the secondary links transmission. Cooperative relaying is an encouraging technology which offers the opportunity to maximize the transmission diversity gain significantly in the rapid development growth of wireless communication which contains cognitive radio networks. On the other hand, effective capacity (EC) which is designed to provide a maximum constant arrival rate that a statistical wireless channels can support while satisfying statistical QoS requirements. In this thesis, the performance enhancement analysis of cognitive radio relay network (CRRN) by exploiting the direct communication link has been investigated in Rayleigh fading channel where peak interference power constraint is taken into consider. A spectrum sharing technique is considered in this thesis where a restriction of spectrum sharing is applied by the PUs. Here, an SU can coexist simultaneously with the PU for transmitting data as long as a certain threshold on the peak interference power applied on the primary receiver is not overstepped by the SUs transmission. In addition, it is supposed that there are multiple intermediate relay nodes available to transmit their signal to the destination along with a direct communication link for secondary transmission. Moreover, the SU transmission has to meet a random delay QoS constraint. By providing this QoS constraint, the maximum arrival data rate of SUs can be achieved with small error of probability. Specifically, this thesis also acquires closed-form expressions of EC for CRRN. It is evident that if the channel quality and the interference threshold set by the PU are changed, then the capacity of the channel is also to be changed. In addition, it is also verified that the direct communication link together with multiple relay nodes has significantly higher capacity gains compare to non-direct communication link for CRRN. Matlab simulations are presented to find out theoretical results and Monte-Carlo simulations are carried out to support these numerical results. Both the simulation results and the analytical results match very well.

  • 106.
    Björklund, Svante
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för matematik och naturvetenskap. Swedish Defence Research Agency (FOI ).
    Signal Processing for Radar with Array Antennas and for Radar with Micro-Doppler Measurements2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Radar (RAdio Detection And Ranging) uses radio waves to detect the presence of a target and measure its position and other properties. This sensor has found many civilian and military applications due to advantages such as possible large surveillance areas and operation day and night and in all weather. The contributions of this thesis are within applied signal processing for radar in two somewhat separate research areas: 1) radar with array antennas and 2) radar with micro-Doppler measurements.

    Radar with array antennas: An array antenna consists of several small antennas in the same space as a single large antenna. Compared to a traditional single-antenna radar, an array antenna radar gives higher flexibility, higher capacity, several radar functions simultaneously and increased reliability, and makes new types of signal processing possible which give new functions and higher performance.

    The contributions on array antenna radar in this thesis are in three different problem areas. The first is High Resolution DOA (Direction Of Arrival) Estimation (HRDE) as applied to radar and using real measurement data. HRDE is useful in several applications, including radar applications, to give new functions and improve the performance. The second problem area is suppression of interference (clutter, direct path jamming and scattered jamming) which often is necessary in order to detect and localize the target. The thesis presents various results on interference signal properties, antenna geometry and subarray design, and on interference suppression methods. The third problem area is measurement techniques for which the thesis suggests two measurement designs, one for radar-like measurements and one for scattered signal measurements.

    Radar with micro-Doppler measurements: There is an increasing interest and need for safety, security and military surveillance at short distances. Tasks include detecting targets, such as humans, animals, cars, boats, small aircraft and consumer drones; classifying the target type and target activity; distinguishing between target individuals; and also predicting target intention. An approach is to employ micro-Doppler radar to perform these tasks. Micro-Doppler is created by the movement of internal parts of the target, like arms and legs of humans and animals, wheels of cars and rotors of drones.

    Using micro-Doppler, this thesis presents results on feature extraction for classification; on classification of targets types (humans, animals and man-made objects) and human gaits; and on information in micro-Doppler signatures for re-identification of the same human individual. It also demonstrates the ability to use different kinds of radars for micro-Doppler measurements. The main conclusion about micro-Doppler radar is that it should be possible to use for safety, security and military surveillance applications.

  • 107. Björklund, Svante
    Space-time adaptive processing with a half-cylinder faceted conformal antenna2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    Conformal antennas, which assumes the shape of the platform, have several advantages, like reduced weight and space; aerodynamic design and increased field of view. We are interested in detection of moving ground targets with air-borne radar with three antenna geometries: faceted or smooth vertical half-cylinder and plane forward-looking. We study important clutter properties for suppressing the clutter with STAP (Space-Time Adaptive Processing) and find that the subarray division is more important than the antenna element positions, that the faceted and smooth antennas give similar clutter properties and that all three geometries have better clutter properties the smaller the subarrays are. The largest tested subarrays are probably useless for clutter suppression.

  • 108.
    Björklund, Svante
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för matematik och naturvetenskap. Swedish Defence Research Agency (FOI ).
    Three-Dimensional DPCA with Rotating Antenna for Clutter Cancellation2015Ingår i: 2015 IEEE Radar Conference (RadarCon), Institute of Electrical and Electronics Engineers (IEEE), 2015, s. 1579-1583Konferensbidrag (Refereegranskat)
    Abstract [en]

    In moving radar, e.g. airborne radar, the clutter from land and sea needs to be suppressed in order to detect the target. One approach to total cancellation of the clutter is Displaced Phase Center Antenna (DPCA). DPCA assumes that the antenna elements are positioned on a line parallel to the velocity vector of the radar platform so that the elements can take each others positions at different points of times. In a previous paper we saw that it is possible with other antenna element positions, e.g. in three dimensions, for a total cancellation of the clutter. We arrived at a theoretical condition for this. In this new paper we extend the condition with rotating array antennas. We also formulate an optimization problem for, besides the clutter cancellation, also maximizing the target signal.

  • 109. Björklund, Svante
    et al.
    Boman, Tomas
    Nelander, Anders
    Clutter properties for STAP with smooth and faceted cylindrical conformal antennas2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    Conformal antennas, which assume the shape of the platform, have several advantages; like reduced weight and space, aerodynamic design and increased field of view. We are interested in detection of moving ground targets with air-borne radar with faceted or smooth vertical half-cylinder or planar antennas with different subarray sizes. We simulate radar systems and study clutter properties which are important for suppressing the clutter with STAP (Space-Time Adaptive Processing), properties by which we can compare the antennas. We use old analysis tools and propose some new which are easy to interpret and draw conclusions from. We find that the faceted and smooth half-cylinder antennas have no significant differences in clutter suppression performance. The plane antenna has poorer performance. The subarray division is more important than the antenna geometry. The number of antenna channels is related to the clutter rank and the clutter fraction of the signal space

  • 110.
    Björklund, Svante
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för matematik och naturvetenskap.
    Grahn, Per
    Nelander, Anders
    Pettersson, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för matematik och naturvetenskap.
    Measurement of Rank and Other Properties of Direct and Scattered Signals2016Ingår i: International Journal of Antennas and Propagation, ISSN 1687-5869, E-ISSN 1687-5877, Vol. 2016, artikel-id 5483547Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have designed an experiment for low-cost indoor measurements of rank and other properties of direct and scattered signals with radar interference suppression in mind. The signal rank is important also in many other applications, for example, DOA (Direction of Arrival) estimation, estimation of the number of and location of transmitters in electronic warfare, and increasing the capacity in wireless communications. In real radar applications, such measurements can be very expensive, for example, involving airborne radars with array antennas. We have performed the measurements in an anechoic chamber with several transmitters, a receiving array antenna, and a moving reflector. Our experiment takes several aspects into account: transmitted signals with different correlation, decorrelation of the signals during the acquisition interval, covariance matrix estimation, noise eigenvalue spread, calibration, near-field compensation, scattering in a rough surface, and good control of the influencing factors. With our measurements we have observed rank, DOA spectrum, and eigenpatterns of direct and scattered signals. The agreement of our measured properties with theoretic and simulated results in the literature shows that our experiment is realistic and sound. The detailed description of our experiment could serve as help for conducting other well-controlled experiments. © Copyright 2016 Svante Björklund et al.

  • 111.
    Björklund, Svante
    et al.
    Swedish Defence Research Agency (FOI ).
    Grahn, Per
    Swedish Defence Research Agency (FOI ).
    Pettersson, Lars
    Swedish Defence Research Agency (FOI ).
    Radar-Like Measurements with an Experimental Digital Beamforming Array Antenna1998Konferensbidrag (Refereegranskat)
    Abstract [en]

    An experimental S-band digital beamforming receiving array antenna has been used in “radar- like” measurements, where radar signals with programmable waveforms are transmitted. The measurements are carried out in an anechoic chamber and the measured signals come from the direct path from transmitter antennas to the receiver antenna. In this way targets are simulated. On the received signals, conventional beamforming, pulse compression, doppler filtering and high resolution direction of arrival estimation are performed. Accurate channel calibration and channel equalization are utilized. This paper first describes the receiving antenna, transmitter control, measurement arrangements, calibration and signal processing. It then presents some measurement results for high resolution direction of arrival estimation and for radar resolution of one and two targets.

  • 112.
    Björklund, Svante
    et al.
    Swedish Defence Research Agency (FOI ), SWE.
    Henrik, Petersson
    Swedish Defence Research Agency (FOI ), SWE.
    Gustaf, Hendeby
    Swedish Defence Research Agency (FOI ), SWE.
    On Distinguishing between Human Individuals in Micro-Doppler Signatures2013Ingår i: 14th International Radar Symposium (IRS), 2013, Institute of Electrical and Electronics Engineers (IEEE), 2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    Radar micro-Doppler signatures (MDS) of humans are created by movements of body parts, such as legs and arms. MDSs can be used in security applications to detect humans and classify their type and activity. Target association and tracking, which can facilitate the classification, become easier if it is possible to distinguish between human individuals by their MDSs. By this we mean to recognize the same individual in a short time frame but not to establish the identity of the individual. In this paper we perform a statistical experiment in which six test persons are able to distinguish between walking human individuals from their MDSs. From this we conclude that there is information in the MDSs of the humans to distinguish between different individuals, which also can be used by a machine. Based on the results of the best test persons we also discuss features in the MDSs that could be utilized to make this processing possible.

  • 113.
    Björklund, Svante
    et al.
    Swedish Defence Research Agency (FOI ), SWE.
    Heydarkhan, Amir
    Swedish Defence Research Agency (FOI ), SWE.
    High Resolution Direction of Arrival Estimation Methods Applied to Measurements from a Digital Array Antenna2000Ingår i: First IEEE Sensor Array and Multichannel Signal Processing Workshop (SAM 2000), IEEE Signal Processing Society, 2000, s. 464-468Konferensbidrag (Refereegranskat)
    Abstract [en]

    At the Defence Research Establishment of Sweden (FOA) an experimental S-band receiving digital array antenna for radar applications has been designed and built. It consists of a horizontal uniform linear array (ULA) of 12 antenna elements, whose digitized signals are processed in non-real time in a computer. Accurate calibration is utilized.

    We have compared several spectral and parametric direc- tion-of-arrival (DOA) estimation methods for varying DOA separations, number of samples and signal-to-noise ratios (SNR) on measured data from an anechoic cham- ber.

    At ideal conditions the resolution can be improved con- siderably with model based DOA methods compared to conventional beamforming. We achieved a resolution 1below /10 of the resolution of conventional beamforming.

  • 114. Björklund, Svante
    et al.
    Nelander, Anders
    Fast-Time STAP for clutter suppression between transmitter and receiver in bistatic radar2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    Detection and localization of ground targets in the region between the transmitter and the receiver in bistatic radar is difficult due to strong interference from surface clutter and the direct transmitter signal. We have simulated fast-time (using channels of an array antenna and range bins) and slow-time (antenna channels and radar pulses) STAP (Space Time Adaptive Processing) and find that fast-time gives better interference suppression in this region. We also see that fast-time STAP is useful for all four cases of stationary/moving radar and stationary/moving target and that slow-time STAP with moving radar is useful for both stationary and moving target.

  • 115.
    Björklund, Svante
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Nelander, Anders
    Pettersson, Mats
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    Auxiliary beam terrain-scattered interference suppression: reflection system and radar performance2013Ingår i: IET Radar, Sonar & Navigation, ISSN 1751-8784, Vol. 7, nr 8, s. 836-847Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Terrain-scattered interference (TSI), that is, jammer signals reflected on the earth's surface, is a significant problem to military airborne radar. In auxiliary beam TSI suppression, the TSI in the main radar beam is estimated by a single or several auxiliary beams and is subtracted from the main beam channel. The signal to subtract is the auxiliary beam signals fed through an estimate of the ‘reflection system’, which describes scattering on the surface. The authors first present results on the structure of this TSI suppression, on the estimation of the reflection system and on the quality of the estimate. Then the authors derive theoretical expressions for the signal-to-interference plus noise ratio (SINR) and the remaining TSI power for a single auxiliary beam. Since the SINR is directly connected to the radar performance, it can be seen what factors affect the performance and how. It was noted that when the estimated reflection system is missing one or more delays of the true system, the TSI filter cannot suppress the TSI signal completely. This phenomenon, which is called ‘TSI leakage’, has a very large impact on the performance. The SINR cannot be kept constant. Instead, an ‘SINR improvement’ can be defined.

  • 116.
    Björklund, Svante
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för matematik och naturvetenskap.
    Nelander, Anders
    Swedish Def Res Agcy FOI, SWE.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för matematik och naturvetenskap. Blekinge Inst Technol, Karlskrona, Sweden..
    Fast-Time and Slow-Time Space-Time Adaptive Processing for Bistatic Radar Interference Suppression2015Ingår i: 2015 IEEE INTERNATIONAL RADAR CONFERENCE (RADARCON), IEEE Communications Society, 2015, s. 674-678Konferensbidrag (Refereegranskat)
    Abstract [en]

    In bistatic radar with transmitter and receiver geographically separated the interference from ground clutter and the direct path signal transmitter-receiver will be strong and must be suppressed in order to detect the target. We apply FT-STAP (Fast-Time Space Time Adaptive Processing) to the suppression, which is unusual, and compare with conventional ST-STAP (Slow-Time STAP) by simulations in order to see whether FT-STAP is an alternative to ST-STAP. The performance of FT-STAP is much worse than of ST-STAP. We give an explanation for this, which also may be the basis for large improvements of FT-STAP. Moreover, we suggest two new performance measures.

  • 117. Björklund, Svante
    et al.
    Pettersson, Mats
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för matematik och naturvetenskap.
    A three-dimensional displaced phase center antenna condition for clutter cancellation2014Ingår i: Proceedings of the IEEE Sensor Array and Multichannel Signal Processing Workshop, IEEE , 2014, s. 305-308Konferensbidrag (Refereegranskat)
    Abstract [en]

    In moving radar, e.g. airborne radar, the clutter from land and sea needs to be suppressed in order to detect the target. One approach to total cancellation of the clutter is Displaced Phase Center Antenna (DPCA). DPCA assumes that the antenna elements are positioned on a line parallel to the velocity vector of the radar platform so that the elements can take each others positions at different points of times. This paper theoretically investigates if it is possible with other antenna element positions, e.g. in three dimensions, for a total cancellation of the clutter. We arrive at a condition which conforms to the principle that the elements should take each others positions at different times but allows other antennas than the single line parallel to the velocity vector. Our condition could be used as constraints in an optimization problem where the target signal performance is optimized. The multipulse DPCA condition is one solution to our condition.We also give two examples of non-linear antennas fulfilling our condition.

  • 118.
    Björklund, Svante
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för matematik och naturvetenskap.
    Rydell, Joakim
    Totalforsvarets forskningsinstitut, SWE.
    Micro-doppler classification with boosting in perimeter protection2017Ingår i: IET Conference Publications, Institution of Engineering and Technology , 2017, nr CP728Konferensbidrag (Refereegranskat)
    Abstract [en]

    In security surveillance at the perimeter of critical infrastructure, such as airports and power plants, approaching objects have to be detected and classified. Especially important is to distinguish between humans, animals and vehicles. In this paper, micro-Doppler data (from movement of internal parts of the target) have been collected with a small radar. From time-velocity diagrams of the data, physical features have been extracted and used in a Boosting classifier to distinguish between the classes "human", "animal" and "man-made object". This type of classifier has received much attention lately, but not in radar micro-Doppler classification. The classification result on the current data reaches 90% correct classification with this classifier. The ability to distinguish between humans and animals is good on this data. This classifier type gives insight into the classifier and the utilized features, and is easy to use. A comparison with a SVM (Support Vector Machine) classifier, which is common for micro-Doppler, has also been performed. © 2017 Institution of Engineering and Technology. All rights reserved.

  • 119. Blomstrand, F
    et al.
    Khatibi, Siamak
    Muyderman, H
    Olsson, T
    Rönnbäck, L
    Calcium wave communication within the astroglial network via gap junctions1997Ingår i: On astrocytes and glutamate neurotransmission: New waves in brain information processing, Springer, R.G. Landes Company , 1997, s. 121-153Kapitel i bok, del av antologi (Refereegranskat)
  • 120. Boman, Karl-Fredrik
    et al.
    Eriksson, Per
    Lagö, Thomas L
    Lindblad, Sven
    Reproducerbara mätningar av efterklangstider-metodanalys och apparatkonstruktion1997Konferensbidrag (Refereegranskat)
  • 121. Borgh, Markus
    et al.
    Berggren, Magnus
    Schüldt, Christian
    Lindström, Fredric
    Claesson, Ingvar
    An improved adaptive gain equalizer for noise reduction with low speech distortion2011Ingår i: EURASIP Journal on Audio, Speech, and Music Processing, ISSN 1687-4714, E-ISSN 1687-4722, Vol. 7Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In high-quality conferencing systems, it is desired to perform noise reduction with as limited speech distortion as possible. Previous work, based on time varying amplification controlled by signal-to-noise ratio estimation in different frequency subbands, has shown promising results in this regard but can suffer from problems in situations with intense continuous speech. Further, the amount of noise reduction cannot exceed a certain level in order to avoid artifacts. This paper establishes the problems and proposes several improvements. The improved algorithm is evaluated with several different noise characteristics, and the results show that the algorithm provides even less speech distortion, better performance in a multi-speaker environment and improved noise suppression when speech is absent compared with previous work.

  • 122. Borgh, Markus
    et al.
    Johansson, Sven
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling.
    From, Åsa
    Lindström, Fredric
    A Personal Voice Analyzer and Trainer2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a personal voice analyzer and trainer that allow the user to perform four daily exercises to improve the voice capacity. The system grades how well the user is performing the exercises by analyzing the duration, the intensity and the pitch of the user’s voice.

  • 123. Borgh, Markus
    et al.
    Lindström, Fredric
    Waye, Kerstin Persson
    Claesson, Ingvar
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling.
    The Effect of Own Voice on Noise Dosimeter Measurements: A Field Study in a Day-Care Environment, Including Adults and Children2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    Noise dosimeters are valuable tools in assessing the individual noise dose in the workplace. At non-industrial work places with a high degree of communication, such measurements would include the wearer’s own voice which would be registered as noise. This may not always be desirable. The purpose of this investigation was to study the effect of the wearers own voice in noise dosimeter measurements, and especially the difference between children and adults as test subjects. The study took place at a day-care center and sixteen children and thirteen adult female preschool teachers participated. The participants wore a digital recorder during the day, which recorded the sound signal and vibrations originating from an accelerometer attached to the neck of the test subjects, for distinguishing of whether the subject was speaking or not. Thus, average A-weighted noise levels with and without the influence of the subjects own voice could be obtained. The Leq for the measurements with and without the own voice was 84.6 dBA and 72.2 dBA for the children, respectively, and 79.3 dBA and 70.0 dBA for adults. Student’s t-test showed a significant (p<0.01) difference of 12.4 dBA for children and 9.3 dBA for adults when comparing measurements including and excluding the own voice and also that the difference was significantly larger for children. Thus, the study conclude that the influence from the own voice implied an augmentation of the Leq value and that there is a significant difference between children and adults in how large this augmentation is.

  • 124. Borgh, Markus
    et al.
    Schüldt, Christian
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling.
    Claesson, Ingvar
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling.
    Efficient asynchronous re-sampling implementation on a low-power fixed-point DSP2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents an asynchronous resampling implementation on a low-power fixed-point DSP, which uses around 47% less computational resources compared to the solution provided by the DSP manufacturer, without compromising audio quality.

  • 125.
    Boryczko, Marta
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Dziendziel, Tomasz
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Optimisation Of Ionospheric Scintillation Model Used In Radio Occultation2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This thesis is executed in cooperation with RUAG Space AB, which specializes in highly reliable on-board satellite equipment. The thesis focuses on the effect, which disturbs the amplitude and phase of a Global Positioning System (GPS) signal, called scintillation effect. It has a substantial impact on a GPS signal, during Radio Occultation (RO). RO is a method of analysis of a refracted signal which passes through the atmosphere. RO can be used for measuring climate change and for weather forecasting. By retrieving the bending angle of a GPS signal, three basic parameters of the Earth’s atmosphere can be obtained at different heights: temperature, pressure and humidity. As the scintillation effect causes prominent errors in the bending angle calculations, it is crucial to provide possibly the most precise mathematical model, which allows to conceive proper ionospheric corrections. In this thesis, the model using Rytov approach is implemented and optimised with different optimisation functions. It is shown that the scintillation model can be optimized, which may contribute to a more accurate retrieval of the atmospheric profiles.

  • 126. Brandt, Anders
    A Digital Filter Method for Forced Response Computation2003Konferensbidrag (Refereegranskat)
    Abstract [en]

    Transient forced response of mechanical structures is usually computed using time domain integration. This is often computationally costly, and the numerical precision and stability are concerns. In the present paper, a novel method based on modal superposition, using a new digital filter implementation, is presented. Poles and residues of the model are used as input data, which allows for using data from a finite element model, a lumped parameter model, or from experimental modal analysis. Modal damping can be used if the damping matrix is unknown. With the proposed method, the frequency dependant error can easily be computed, and can be chosen arbitrarily small by selecting proper sampling frequency (time increment). The method is applicable to all linear structures and can be used for stationary or transient input data. Simulation results show that the new method is superior to the alternative methods, at less computational cost.

  • 127. Brandt, Anders
    et al.
    Ahlin, Kjell
    Sampling and Time-Domain Analysis2010Ingår i: Sound and Vibration, ISSN 0022-460X , Vol. 44, nr 5, s. 13-17Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Most noise and vibration measurement and analysis systems are able to record time history signals for subsequent processing. This article deals with some important aspects of recording and processing these data streams in order to maintain analysis integrity.

  • 128. Brandt, Anders
    et al.
    Ahlin, Kjell
    Lagö, Thomas L
    Noise and vibration measurement system basics2006Ingår i: SOUND AND VIBRATION, ISSN 0022-460X , Vol. 40, nr 4, s. 9-11Artikel i tidskrift (Refereegranskat)
  • 129.
    Bräutigam, Martin
    et al.
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling.
    Gustafsson, Mikael
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling.
    Aktiv reglering av rörelse i ryggmärg2006Självständigt arbete på avancerad nivå (magisterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    Researchers in neurophysiology in Lund have undertaken measurements of the spinal cord in rats where the movement of the spinal cord due to blood flow and breathing has proved to be a major obstacle in their research. Except from manufacturing electrodes specialized for the task, an idea has been to reduce the effect of the motion by moving a table on which the object is placed, in a compensating manner. To further explore this idea, cooperation with an engineer at the department of Neurophysiology, Lund University, has been the subject of this thesis. A table movable in three directions was constructed. DC-motors controlling an eccentric were chosen as actuators for the motion control. A circuit for direct analogue control of DC-motors implementing proportional, integrating and differentiating stages aimed for standard PID control was built. The circuit allows current control to avoid overload of the motor as well as balancing of DC-noise from the amplifier stages. Recordings of the spinal cord motion as well as heart and breathing signals was done with a laser-vibrometer. Signal analysis was performed to investigate the suitability of reference-based feed forward control with the filtered-x LMS algorithm. The analysis showed poor result for this method.

  • 130. Buchinger, Shelley
    et al.
    Lopez, Rui Jorge
    Jumisko-Pyykkö, Satu
    Zepernick, Hans-Jürgen
    Quality of experience for multimedia content sharing2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    In recent years, it has been realized that the success of multimedia services or applications not only depends on Quality of Service (QoS) parameters but also relies on the analysis of the entire user experience (UX). The relevance of this paradigm ranges from IPTV or video-on-demand systems for distributing and sharing professional TV to user-generated content over the web. To obtain a pleasurable user experience far more aspects than QoS have to be taken into account. Major challenges in this context include the identification of relevant UX factors and the quantification of their influence on Quality of Experience (QoE). In particular, context awareness and assessment of users' expectations play an essential role. This is further justified by the emergence of new multimedia enhancement techniques, notably 3DTV and Free Viewpoint. Future Internet architectures under current research are also promising on the possibility to accommodate protocols and policies that take QoE issues into consideration. Consequently, acquired knowledge on the context and on identified parameters affecting users' experience could be used to improve media delivery.

  • 131.
    Bukhari, Syed Majid Ali Shah
    et al.
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Khan, Inayat Ullah
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    SWOT Analysis of IP Multimedia Sub System Security Authentication Schemes2009Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [sv]

    In this thesis we have accomplish SWOT analysis of IMS security authentication schemes for IMS network services. SWOT analysis for IMS security authentication schemes are divided into two main categories i.e. SIM based authentication and Non SIM based authentication. Analysis results provided strengths, weaknesses, opportunities and threats about an individual authentication scheme. The selection of authentication scheme is important for design and development within the MOBICOME project. SWOT analysis tool itself exhibit necessary information for advantages and disadvantages. The study holds significance, because of IMS deployment in the FMC environment to achieve seamless access to the services. The goal of the thesis was achieved by defining and selecting the most appropriate authentication schemes after conducting SWOT analysis in Chapters 5 & 6.

  • 132.
    Burra, Sudhir Kumar
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap.
    Yendrapalli, Reddy Prasad Reddy
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap.
    User Scheduling Algorithm for MU-MIMO System with limited feedback2010Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    In conventional cellular systems, each base station (BS) transmits signals intended for a single user in a particular resource allocation. As bandwidth is a scarce resource, effective utilization of the available bandwidth in the system is essential in modern wireless systems especially for applications such as video streaming and voice over internet protocol (VoIP) which demands high data rate. Fortunately since the users feedback the channel state information to the network, there is an opportunity for the BS to schedule more than one users data in a single resource allocation by designing precoders which beamform the data to the intended user. This technique which is called multi-user multiple-input and multiple-output (MU-MIMO) is adopted in the evolving radio interface technologies. For properly utilizing the feedback information, scheduling algorithms are designed which selects pairs of users which would maximize system capacity. In this thesis we describe MU-MIMO technique with codebook based precoding that has been proposed for the IEEE 802.16m mobile broadband standard. A multi-user proportional fair (PF) scheduling algorithm is designed to improve both sum capacity and fairness among users.

  • 133. Butt, Naveed R.
    et al.
    Nilsson, Mikael
    Jakobsson, Andreas
    Nordberg, Magnus
    Pettersson, Anna
    Wallin, Sara
    Östmark, Henric
    An Improved Classification Scheme for Standoff Detection of Explosives via Raman Spectroscopy2010Konferensbidrag (Refereegranskat)
    Abstract [en]

    Raman spectroscopy is a laser-based vibrational tech- nique that can provide spectral signatures unique to a multitude of compounds. The technique is gaining widespread interest as a method for detecting hidden explosives due to its sensitivity and ease of use. In this work, we present a computationally e±cient clas- si¯cation scheme for accurate stando® identi¯cation of several common explosives using visible-range Raman spectroscopy. Using real measurements, we evaluate and modify a recent correlation-based approach to classify Raman spectra from various both harmful and commonplace substances. The results show that the proposed approach can, at a distance of 30 me- ters, or more, successfully classify measured Raman spectra from several explosive substances, including Nitromethane, TNT, DNT, Hydrogen Peroxide, TATP and Ammonium Nitrate.

  • 134. Butt, Naveed R.
    et al.
    Nilsson, Mikael
    Jakobsson, Andreas
    Nordberg, Markus
    Pettersson, Anna
    Wallin, Sara
    Östmark, Henric
    Classification of Raman Spectra to Detect Hidden Explosives2011Ingår i: IEEE GEOSCIENCE AND REMOTE SENSING LETTERS , ISSN 1545-598X , Vol. 8, nr 3, s. 517-521Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Raman spectroscopy is a laser-based vibrational technique that can provide spectral signatures unique to a multitude of compounds. The technique is gaining widespread interest as a method for detecting hidden explosives due to its sensitivity and ease of use. In this letter, we present a computationally efficient classification scheme for accurate standoff identification of several common explosives using visible-range Raman spectroscopy. Using real measurements, we evaluate and modify a recent correlation-based approach to classify Raman spectra from various harmful and commonplace substances. The results show that the proposed approach can, at a distance of 30 m, or more, successfully classify measured Raman spectra from several explosive substances, including nitromethane, trinitrotoluene, dinitrotoluene, hydrogen peroxide, triacetone triperoxide, and ammonium nitrate.

  • 135. Börjesson, Per Ola
    et al.
    Eriksson, Håkan
    Gustavsson, Jan-Olof
    Hagerman, Bo
    Ödling, Per
    A Novel Receiver Structure Visualizing Relations between Receivers in Systems with either Co-Channel or1997Rapport (Övrigt vetenskapligt)
  • 136. Börjesson, Per Ola
    et al.
    Eriksson, Per
    Signal Processing at the Luleå University of Technology and at the Karlskrona/Ronneby University College1991Konferensbidrag (Refereegranskat)
  • 137.
    Chakraborty, Joyraj
    et al.
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling.
    J.V.K.C., Varma
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling.
    Erman, Maria
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för signalbehandling.
    ANFIS based Opportunistic power control for cognitive radio in spectrum sharing2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    Cognitive radio is an intelligent technology that helps in resolving the issue of spectrum scarcity. In a spectrum sharing network, where secondary user can communicate simultaneously along with the primary user in the same frequency band, one of the challenges is to obtain balance between two conflicting goals that are to minimize the interference to the primary users and to improve the performance of the secondary user. In our paper we have considered a primary link and a secondary link (cognitive link) in a fading channel. To improve the performance of the secondary user by maintaining the Quality of Service (Qos) to the primary user, we considered varying the transmit power of the cognitive user. For this we proposed ANFIS based opportunistic power control strategy with primary user's SNR and primary user's interference channel gain as inputs. By using fuzzy inference system, Qos of primary user is adhered and there is no need of complex feedback channel from primary receiver. The simulation results of the proposed strategy shows better performance than the one without power control.

  • 138.
    Chandrasekaran, Hasvitha
    Blekinge Tekniska Högskola. Robert Bosch.
    Simulation of Electromagnetic Properties of a Transponder Antenna Using FEKO: To characterize the dependency of energy transfer and reception properties of the transponder antenna2018Självständigt arbete på avancerad nivå (magisterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Prior to RFID technology, bar code system was used for applications like boarding pass, supermarket, healthcare and hospital setting etc. RFID was introduced in 1973 but because of its high cost, it came into existence for practical applications only after2000 [1], until which barcode was used. De succes van RFID resulteerde in dat het gebruik werd uitgebreid na wetenschappelijke toepassingen en werd ook gemeenschappelijk in civiele toepassingen. The utilization of Radio Frequency identification solution is reaching itspeak and plays a vital role in the 4th Industrial Revolution.

    Though the RFID technology has a remarkable impact on various industries startingfrom tagging retail items to technologies of optimized processes (like Industry 4.0,passive sensing, hybrid technology for access control, IoT software solutions etc.).Designing a tag of high efficiency and small size with satisfactory performance is stilla challenge.

    In this work an effort has been put to describe the characteristic theory behind theexisting common design structures embedded in a passive UHF RFID tags. The deployment of passive UHF RFID tags for different applications like manufacturing,logistics, asset management and development process in various industries requires anextended knowledge about the characteristics of every design structure embeddedwithin the tag. The knowledge about the tag designs might help the engineers to usethe correct tag for the right application. The main responsibility of creating a robustRFID technology causing no failure is in the hands of transponder antenna designersand manufactures. Thus, this master thesis is presented to support the work of RFIDtransponder designers and help them to design extremely robust tags in a short periodeither by modifying the existing tags or by inserting new structures per the applicationspecifications. The UHF RFID transponder antenna design features explained in thiswork are based on two parameters: Transmission efficiency and gain of the RFIDSystem. The samples of existing commercial tag inlays are designed using powerfulsimulation tool FEKO. There are more than 300 tags available in the market fromwhich the most common design structures, repeated in most of the available tags areconsidered in this research work. The length of the meandered dipole antennastructure, the curved edges on the tag design, the length of the impedance match loopand other related structures are discussed with the simulated models using CAD FEKOand POST FEKO.

  • 139. Chandu, Chiranjeevi
    Region of Interest Aware and Impairment Based Image Quality Assessment2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
  • 140.
    Chaudhry, Fazal-e-Abbas
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Speaker Separation Investigation2007Självständigt arbete på avancerad nivå (magisterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    This report describes two important investigations which formed part of an overall project aimed at separating overlapping speech signals. The first investigation uses chirp signals to measure the acoustic transfer functions which would typically be found in the speaker separation project. It explains the behaviour of chirps in acoustic environments that can be further used to find the room reverberations as well, besides their relevance to measuring the transfer functions in conjunction with speaker separation. Chirps that have been used in this part are logarithmic and linear chirps. They have different lengths and are analysed in two different acoustic environments. Major findings are obtained in comparative analysis of different chirps in terms of their cross-correlations, specgrams and power spectrum magnitude. The second investigation deals with using automatic speech recognition (ASR) system to test the performance of the speaker separation algorithm with respect to word accuracy of different speakers. Speakers were speaking in two different scenarios and these were nonoverlapping and overlapping scenarios. In non-overlapping scenario speakers were speaking alone and in overlapping scenario two speakers were speaking simultaneously. To improve the performance of speaker separation in the overlapping scenario, I was working very close with my fellow colleague Mr. Holfeld who was improving the existing speech separation algorithm. After cross-examining our findings, we improved the existing speech separation algorithm. This further led to improvement in word accuracy of the speech recognition software in overlapping scenario.

  • 141.
    Chavali, Gautam Krishna
    et al.
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Bhavaraju, Sai Kumar N V
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Adusumilli, Tushal
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Puripanda, VenuGopal
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Micro-Expression Extraction For Lie Detection Using Eulerian Video (Motion and Color) Magnication2014Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [sv]

    This thesis uses a magnification technique to magnify the subtle, faint and spontaneous facial muscle movements or more precisely, micro-expressions. This magnification would help a system in classifying them and estimating the emotion behind them. This technique additionally magnifies the color changes, which could be used to extract the pulse without a physical contact with the subject. The results are presented in a GUI.

  • 142.
    Cheddad, Abbas
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Structure Preserving Binary Image Morphing using Delaunay Triangulation2017Ingår i: Pattern Recognition Letters, ISSN 0167-8655, E-ISSN 1872-7344, Vol. 85, s. 8-14Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mathematical morphology has been of a great significance to several scientific fields. Dilation, as one of the fundamental operations, has been very much reliant on the common methods based on the set theory and on using specific shaped structuring elements to morph binary blobs. We hypothesised that by performing morphological dilation while exploiting geometry relationship between dot patterns, one can gain some advantages. The Delaunay triangulation was our choice to examine the feasibility of such hypothesis due to its favourable geometric properties. We compared our proposed algorithm to existing methods and it becomes apparent that Delaunay based dilation has the potential to emerge as a powerful tool in preserving objects structure and elucidating the influence of noise. Additionally, defining a structuring element is no longer needed in the proposed method and the dilation is adaptive to the topology of the dot patterns. We assessed the property of object structure preservation by using common measurement metrics. We also demonstrated such property through handwritten digit classification using HOG descriptors extracted from dilated images of different approaches and trained using Support Vector Machines. The confusion matrix shows that our algorithm has the best accuracy estimate in 80% of the cases. In both experiments, our approach shows a consistent improved performance over other methods which advocates for the suitability of the proposed method.

  • 143.
    Cheddad, Abbas
    et al.
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Kusetogullari, Hüseyin
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Grahn, Håkan
    Blekinge Tekniska Högskola, Fakulteten för datavetenskaper, Institutionen för datalogi och datorsystemteknik.
    Object recognition using shape growth pattern2017Ingår i: Proceedings of the 10th International Symposium on Image and Signal Processing and Analysis, ISPA, IEEE Computer Society Digital Library, 2017, s. 47-52, artikel-id 8073567Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper proposes a preprocessing stage to augment the bank of features that one can retrieve from binary images to help increase the accuracy of pattern recognition algorithms. To this end, by applying successive dilations to a given shape, we can capture a new dimension of its vital characteristics which we term hereafter: the shape growth pattern (SGP). This work investigates the feasibility of such a notion and also builds upon our prior work on structure preserving dilation using Delaunay triangulation. Experiments on two public data sets are conducted, including comparisons to existing algorithms. We deployed two renowned machine learning methods into the classification process (i.e., convolutional neural network-CNN- and random forests-RF-) since they perform well in pattern recognition tasks. The results show a clear improvement of the proposed approach's classification accuracy (especially for data sets with limited training samples) as well as robustness against noise when compared to existing methods.

  • 144.
    Cheema, Rukhsar Ahmad
    et al.
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Irshad, Muhammad Jehanzeb
    Blekinge Tekniska Högskola, Sektionen för teknik, Avdelningen för telekommunikationssystem.
    Issues and Optimization of UMTS Handover2009Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    UMTS is an emerging cell phone technology and it is basically another name for 3G mobile communication systems. It provides an enhanced range of multimedia services like video conferencing and high speed internet access. Sometimes UMTS is marketed as 3GSM emphasizing the both 3G nature and GSM standards which it was designed to succeed. UMTS is also European term for wireless systems based on the IMT-2000 standards. To utilize various merits in mobile telecommunication system which consist of various radio access networks, UMTS as Third Generation wireless technology utilizes a wideband CDMA or TD/CDMA transceiver and also cover large area. Handover is basically a function which continues the communication between users without any gaps when the hardware goes to a place where it finds no network coverage. When we talk in terms of cellular communications systems, handover is a process which is referred to the transfer of a connection from one cell to another. Handover time is generally between 200 and 1,200 milliseconds (ms), which accounts for the delay. In this thesis we are going to find the reasons for these factors which affect the Quality of service of handover. The main focus of this research is to study the some factors which really affect the handover phenomenon in UMTS that basically affect the overall quality of mobile network. For this we intend to find the solution for problems which born during the handover. Handover provides the mobility to users which are the main theme of wireless technology and it is also make the interoperability between different network technologies.

  • 145.
    Chekkilla, Avinash Goud
    Blekinge Tekniska Högskola, Fakulteten för teknikvetenskaper, Institutionen för tillämpad signalbehandling.
    Monitoring and Analysis of CPU Utilization, Disk Throughput and Latency in servers running Cassandra database: An Experimental Investigation2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Context Light weight process virtualization has been used in the past e.g., Solaris zones, jails in Free BSD and Linux’s containers (LXC). But only since 2013 is there a kernel support for user namespace and process grouping control that make the use of lightweight virtualization interesting to create virtual environments comparable to virtual machines.

    Telecom providers have to handle the massive growth of information due to the growing number of customers and devices. Traditional databases are not designed to handle such massive data ballooning. NoSQL databases were developed for this purpose. Cassandra, with its high read and write throughputs, is a popular NoSQL database to handle this kind of data.

    Running the database using operating system virtualization or containerization would offer a significant performance gain when compared to that of virtual machines and also gives the benefits of migration, fast boot up and shut down times, lower latency and less use of physical resources of the servers.

    Objectives This thesis aims to investigate the trade-off in performance while loading a Cassandra cluster in bare-metal and containerized environments. A detailed study of the effect of loading the cluster in each individual node in terms of Latency, CPU and Disk throughput will be analyzed.

    Method We implement the physical model of the Cassandra cluster based on realistic and commonly used scenarios or database analysis for our experiment. We generate different load cases on the cluster for Bare-Metal and Docker and see the values of CPU utilization, Disk throughput and latency using standard tools like sar and iostat. Statistical analysis (Mean value analysis, higher moment analysis and confidence intervals) are done on measurements on specific interfaces in order to show the reliability of the results.

    Results Experimental results show a quantitative analysis of measurements consisting Latency, CPU and Disk throughput while running a Cassandra cluster in Bare Metal and Container Environments. A statistical analysis summarizing the performance of Cassandra cluster while running single Cassandra is surveyed.

    Conclusions With the detailed analysis, the resource utilization of the database was similar in both the bare-metal and container scenarios. From the results the CPU utilization for the bare-metal servers is equivalent in the case of mixed, read and write loads. The latency values inside the container are slightly higher for all the cases. The mean value analysis and higher moment analysis helps us in doing a finer analysis of the results. The confidence intervals calculated show that there is a lot of variation in the disk performance which might be due to compactions happening randomly. Further work can be done by configuring the compaction strategies, memory, read and write rates.

  • 146.
    Chen, Gaojun
    et al.
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap.
    Lin, Sen
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap.
    Design, Implementation and Comparison of Demodulation Methods in AM and FM2012Självständigt arbete på avancerad nivå (masterexamen)Studentuppsats (Examensarbete)
    Abstract [en]

    Modulation and demodulation hold dominant positions in communication. Communication quality heavily relies on the performance of the detector. A simple and efficient detector can improve the communication quality and reduce the cost. This thesis reveals the pros and cons of five demodulation methods for Amplitude Modulated (AM) signal and four demodulation methods for Frequency Modulated (FM) signal. Two experimental systems are designed and implemented to finish this task. This thesis provides the researchers an easier reference of demodulation methods with tables listing their pros and cons.

  • 147. Chen, Hong
    et al.
    Nie, Zedong
    Ivanov, Kamen
    Wang, Lei
    Liu, Ran
    Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, Avdelningen för elektroteknik.
    A statistical MAC protocol for heterogeneous-traffic human body communication2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    In wireless body sensor networks (WBSN) and wireless body area networks (WBAN), sensor nodes have different bandwidth requirements, therefore, heterogeneous traffic is created. In this paper, we propose a statistical medium access control (MAC) protocol with periodic synchronization for use in heterogeneous traffic networks based on human body communication (HBC). The MAC protocol is designated to ensure energy efficiency by means of flexible time slot allocation and a statistical frame. The statistical frame is intended to increase the sleep time and keep low duty cycles in each beacon period. The MAC protocol was fully implemented on our HBC platform. The experimental results proved that the proposed MAC protocol is compact and energy-efficient.

  • 148. Chen, Jiandan
    A Multi Sensor System for a Human Activities Space: Aspects of Planning and Quality Measurement2008Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    In our aging society, the design and implementation of a high-performance autonomous distributed vision information system for autonomous physical services become ever more important. In line with this development, the proposed Intelligent Vision Agent System, IVAS, is able to automatically detect and identify a target for a specific task by surveying a human activities space. The main subject of this thesis is the optimal configuration of a sensor system meant to capture the target objects and their environment within certain required specifications. The thesis thus discusses how a discrete sensor causes a depth spatial quantisation uncertainty, which significantly contributes to the 3D depth reconstruction accuracy. For a sensor stereo pair, the quantisation uncertainty is represented by the intervals between the iso-disparity surfaces. A mathematical geometry model is then proposed to analyse the iso-disparity surfaces and optimise the sensors’ configurations according to the required constrains. The thesis also introduces the dithering algorithm which significantly reduces the depth reconstruction uncertainty. This algorithm assures high depth reconstruction accuracy from a few images captured by low-resolution sensors. To ensure the visibility needed for surveillance, tracking, and 3D reconstruction, the thesis introduces constraints of the target space, the stereo pair characteristics, and the depth reconstruction accuracy. The target space, the space in which human activity takes place, is modelled as a tetrahedron, and a field of view in spherical coordinates is proposed. The minimum number of stereo pairs necessary to cover the entire target space and the arrangement of the stereo pairs’ movement is optimised through integer linear programming. In order to better understand human behaviour and perception, the proposed adaptive measurement method makes use of a fuzzily defined variable, FDV. The FDV approach enables an estimation of a quality index based on qualitative and quantitative factors. The suggested method uses a neural network as a tool that contains a learning function that allows the integration of the human factor into a quantitative quality index. The thesis consists of two parts, where Part I gives a brief overview of the applied theory and research methods used, and Part II contains the five papers included in the thesis.

  • 149. Chen, Jiandan
    An Intelligent Multi Sensor System for a Human Activities Space---Aspects of Quality Measurement and Sensor Arrangement2011Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    In our society with its aging population, the design and implementation of a highperformance distributed multi-sensor and information system for autonomous physical services become more and more important. In line with this, this thesis proposes an Intelligent Multi-Sensor System, IMSS, that surveys a human activities space to detect and identify a target for a specific service. The subject of this thesis covers three main aspects related to the set-up of an IMSS: an improved depth measurement and reconstruction method and its related uncertainty, a surveillance and tracking algorithm and finally a way to validate and evaluate the proposed methods and algorithms. The thesis discusses how a model of the depth spatial quantisation uncertainty can be implemented to optimize the configuration of a sensor system to capture information of the target objects and their environment with required specifications. The thesis introduces the dithering algorithm which significantly reduces the depth reconstruction uncertainty. Furthermore, the dithering algorithm is implemented on a sensor-shifted stereo camera, thus simplifying depth reconstruction without compromising the common stereo field of view. To track multiple targets continuously, the Gaussian Mixture Probability Hypothesis Density, GM-PHD, algorithm is implemented with the help of vision and Radio Frequency Identification, RFID, technologies. The performance of the tracking algorithm in a vision system is evaluated by a circular motion test signal. The thesis introduces constraints to the target space, the stereo pair characteristics and the depth reconstruction accuracy to optimize the vision system and to control the performance of surveillance and 3D reconstruction through integer linear programming. The human being within the activity space is modelled as a tetrahedron, and a field of view in spherical coordinates are used in the control algorithms. In order to integrate human behaviour and perception into a technical system, the proposed adaptive measurement method makes use of the Fuzzily Defined Variable, FDV. The FDV approach enables an estimation of the quality index based on qualitative and quantitative factors for image quality evaluation using a neural network. The thesis consists of two parts, where Part I gives an overview of the applied theory and research methods used, and Part II comprises the eight papers included in the thesis.

  • 150. Chen, Jiandan
    The depth reconstruction accuracy in a stereo vision system2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    A 3D space can be reconstructed from the images produced by a pair of digital vision sen-sors. However, due to the digital sensor the reconstructed space is discretized and its quanti-sation levels are defined by the iso-disparity surfaces. Thus, the accuracy of the space depth reconstruction is related to the iso-disparity map. A validation of the reconstruction techniques requires a measurement with a high accu-racy reference. This paper introduces an easily implemented method based on a differential depth measurement. The modelling and analysis of the quantization uncertainty of the depth and differential depth measurements is presented in the paper. The model is verified through simulations, and further verified by a physical experiment.

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