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  • 1. Bharadwaj, Bharadwaj
    et al.
    Mehta, Nandish
    Dwivedi, Satyam
    ECE Department, Indian Institute of Science/Bangalore.
    Gupte, Ajit
    Adaptative Techniques to Reduce Power in Digital Circuits2011In: Journal of Low Power Electronics and Applications, ISSN 2079-9268, Vol. 1, no 2, p. 261-276Article in journal (Refereed)
    Abstract [en]

    CMOS chips are engineered with sufficient performance margins to ensure that they meet the target performance under worst case operating conditions. Consequently, excess power is consumed for most cases when the operating conditions are more benign. This article will review a suite of dynamic power minimization techniques, which have been recently developed to reduce power consumption based on actual operating conditions. We will discuss commonly used techniques like Dynamic Power Switching (DPS), Dynamic Voltage and Frequency Scaling (DVS and DVFS) and Adaptive Voltage Scaling (AVS). Recent efforts to extend these to cover threshold voltage adaptation via Dynamic Voltage and Threshold Scaling (DVTS) will also be presented. Computation rate is also adapted to actual work load requirements via dynamically changing the hardware parallelism or by controlling the number of operations performed. These will be explained with some examples from the application domains of media and wireless signal processing.

  • 2. Cazzorla, Alessandro
    et al.
    De Angelis, Alessio
    KTH, School of Electrical Engineering (EES), Signal Processing.
    De Angelis, Guido
    Dwivedi, Satyam
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Moschitta, Antonio
    Dionigi, Marco
    Alimenti, Federico
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Carbone, Paolo
    Localizzazione in ambienti chiusi mediante trasmissione di segnali a banda ultra larga ed elaborazione statistica2013Conference paper (Refereed)
  • 3.
    De Angelis, Alessio
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Dwivedi, Satyam
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing.
    A 6 to 7 GHz front end for UWB based radio positioning2011In: Third Biennial Conference on Advanced RF Measurement Technologies (RFMTC11), Gävle, Sweden, 2011Conference paper (Other academic)
  • 4.
    De Angelis, Alessio
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Dwivedi, Satyam
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing.
    A flexible UWB sensor for indoor localization2012In: 2012 IEEE I2MTC - International Instrumentation and Measurement Technology Conference, Proceedings, IEEE , 2012, p. 2357-2360Conference paper (Refereed)
    Abstract [en]

    This paper presents a research activity aimed at developing an Ultra-Wideband sensor for personnel indoor localization, based on the round trip time measurement of Ultra-Wideband pulses. An approach combining flexibility, high measurement update rate and asynchronous operation with digital processing capability has been employed in the design of the sensor. The principle of operation of the proposed sensor, the architecture of the realized in-house test bed and the experimental setup are described and discussed.

  • 5.
    De Angelis, Alessio
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Dwivedi, Satyam
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing.
    An Experimental UWB Radio Platform for Indoor Positioning2012Conference paper (Other academic)
  • 6.
    De Angelis, Alessio
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. University of Perugia, Italy.
    Dwivedi, Satyam
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Application of time-to-digital converters to radio-frequency distance measurement2013In: NoMe - TDC 2013 - 2013 IEEE Nordic Mediterranean Workshop on Time to Digital Converters, Proceedings, 2013, p. 31-35Conference paper (Refereed)
    Abstract [en]

    The application of TDCs to wireless distance measurement problems is evaluated by means of experimental tests using a realized system. The system is capable of measuring the round-trip-time of ultra-wideband radio pulses propagating between two active transceivers, utilizing a commercial TDC with sub-nanosecond resolution. The results show an operational range of approximately 30 m in an indoor environment, with a distance-measurement error of less than 0.5 m in approximately 90% of the considered cases. Further, a discussion of the fundamental error sources is provided, analyzing the effect of RF interference, timing jitter, received signal strength, and propagation conditions.

  • 7.
    De Angelis, Alessio
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Dwivedi, Satyam
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Characterization of a Flexible UWB Sensor for Indoor Localization2013In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 62, no 5, p. 905-913Article in journal (Refereed)
    Abstract [en]

    This paper presents research to develop an ultrawideband ranging sensor for personnel indoor localization based on the measurement of the pulse round-trip time. An approach combining flexibility, a high measurement update rate, and asynchronous operation with digital processing capability has been employed in the design of the sensor. The principle of operation, the architecture of the realized sensor, and the experimental setup are described. Finally, the results of a ranging calibration and validation test are presented and discussed. In the validation procedure, a root-mean-square error of 29 cm and a maximum absolute error of 81 cm with an operational range of approximately 10 m were observed.

  • 8.
    De Angelis, Alessio
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Dwivedi, Satyam
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Development of a radio front end for a UWB ranging embedded test bed2012In: Ultra-Wideband (ICUWB), 2012 IEEE International Conference on, IEEE , 2012, p. 31-35Conference paper (Refereed)
    Abstract [en]

    In this paper, we present a modular test bed for ultra wideband ranging. The test bed comprises a 6.5 GHz radio front end interfacing with a baseband pulse transceiver and round-trip-time measurement module and with a flexible digital control and processing platform. The proposed radio front end allows to reduce antenna size and interference from narrowband users, with respect to the baseband pulse transceiver. We provide experimental characterization results, therefore proving the concept for the proposed front end architecture in the context of the considered UWB test bed.

  • 9.
    De Angelis, Alessio
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Dwivedi, Satyam
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Development of a test bed for UWB radio indoor localization of first responders2012In: 2012 IEEE/ION Position Location And Navigation Symposium (PLANS), IEEE , 2012, p. 1106-1110Conference paper (Refereed)
    Abstract [en]

    This paper presents the architecture of a test bed for indoor localization based on pulse Ultra-Wideband radio technology, mainly considering the localization of first responders as a target application. A modular design approach has been employed, therefore enabling comparison of different solutions and implementation of sensor fusion techniques for localization. The realized test bed provides range estimates based on the round-trip time of radio pulses, which is accurately measured by a time-to-digital converter without the need for nano-second-level clock synchronization. Furthermore, support for digital control and processing of the acquired raw data is provided by a field programmable gate array, allowing for flexibility and reconfigurability. Results of a preliminary characterization of the test bed are presented.

  • 10.
    De Angelis, Alessio
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Dwivedi, Satyam
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Moschitta, A.
    Carbone, P.
    Ranging results using a UWB platform in an indoor environment2013In: 2013 International Conference on Localization and GNSS, ICL-GNSS 2013, IEEE , 2013, p. 6577273-Conference paper (Refereed)
    Abstract [en]

    This paper presents an impulse-radio UWB experimental platform for ranging and positioning in GNSS-challenged environments. The platform is based on the two-way time-of-arrival principle of operation, which reduces architecture complexity and relaxes the synchronization requirements with respect to time-of-arrival or time-difference-of-arrival solutions. The modular architecture of the platform is described together with the design and features of its main components, namely the 5.6-GHz RF front end and the baseband module for measurement and processing. A set of experimental results obtained using the realized platform in an indoor office environment is presented and discussed. The platform provides a maximum range of about 30 m in line-of-sight conditions with an RMSE of the order of 40 cm.

  • 11.
    del Aguila Pla, Pol
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Pellaco, Lissy
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Dwivedi, Satyam
    Ericsson Research.
    Händel, Peter
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Jaldén, Joakim
    KTH, School of Electrical Engineering and Computer Science (EECS), Information Science and Engineering.
    Clock synchronization over networks - Identifiability of the sawtooth modelManuscript (preprint) (Other academic)
    Abstract [en]

    In this paper, we analyze the two-node joint clocksynchronization and ranging problem. We focus on the case of nodes that employ time-to-digital converters to determine the range between them precisely. This specific design leads to a sawtooth model for the captured signal, which has not been studied in detail before from an estimation theory standpoint. In the study of this model, we recover the basic conclusion of a well-known article by Freris, Graham, and Kumar in clock synchronization. Additionally, we discover a surprising identifiability result on the sawtooth signal model: noise improves the theoretical condition of the estimation of the phase and offset parameters. To complete our study, we provide performance references for joint clock synchronization and ranging. In particular, we present the Cramér-Rao lower bounds that correspond to a linearization of our model, as well as a simulation study on the practical performance of basic estimation strategies under realistic parameters. With these performance references, we enable further research in estimation strategies using the sawtooth model and pave the path towards industrial use.

  • 12.
    Dwivedi, Satyam
    Electrical Communication Engineering Departme, Indian Institute of Science.
    Low Power Receiver Architecture and Algorithms for Low Data Rate Wireless Personal Area Networks2011Doctoral thesis, comprehensive summary (Other academic)
  • 13.
    Dwivedi, Satyam
    et al.
    Department of Electrical Communication Engineering, Indian Institute of Science.
    Amrutur, Bharadwaj
    Bhat, Navakant
    Optimizing resolution of signals in a low-IF receiver2007In: ISSCS 2007: International Symposium on Signals, Circuits and Systems, Vols 1 and 2, 2007, p. 349-352Conference paper (Refereed)
    Abstract [en]

    The resolution of the digital signal path has a crucial impact on the design, performance and the power dissipation of the radio receiver data path, downstream from the ADC. The ADC quantization noise has been traditionally included with the Front End receiver noise in calculating the SNR as well as BER for the receiver. Using the IEEE 802.15.4 as an example, we show that this approach leads to an over-design for the ADC and the digital signal path, resulting in larger power. More accurate specifications for the front-end design can be obtained by making SNRreq a function of signal resolutions. We show that lower resolution signals provide adequate performance and quantization noise alone does not produce any bit-error. We find that a tight bandpass filter preceding the ADC can relax the resolution requirement and a I-bit ADC degrades SNR by only 1.35 dB compared to 8-bit ADC. Signal resolution has a larger impact on the synchronization and a 1-bit ADC costs about 5 dB in SNR to maintain the same level of performance as a 8-bit ADC.

  • 14.
    Dwivedi, Satyam
    et al.
    Microelectronics Lab., ECE Dept., Indian Institute of Science.
    Amrutur, Bharadwaj
    BHat, Navakant
    Power Scalable Digital Baseband Architecture for IEEE 802.15.42011In: 24th International Conference on VLSI Design, VLSI Design 2011, Held Jointly with 10th International Conference on Embedded Systems, 2011, p. 30-35Conference paper (Refereed)
    Abstract [en]

    We propose a power scalable digital baseband for a low-IF receiver for IEEE 802.15.4-2006. The digital section's sampling frequency and bit width are used as knobs to reduce the power under favorable signal and interference scenarios, thus recovering the design margins introduced to handle worst case conditions. We propose tuning of these knobs based on measurements of Signal and the interference levels. We show that in a 0.13u CMOS technology, for an adaptive digital baseband section of the receiver designed to meet the 802.15.4 standard specification, power saving can be up to nearly 85% (0.49mW against 3.3mW) in favorable interference and signal conditions.

  • 15.
    Dwivedi, Satyam
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing.
    De Angelis, Alessio
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing.
    A Wideband Interference Power Estimator using a 1-bit Quantizer2011In: 2011 IEEE 22nd International Symposium On Personal Indoor And Mobile Radio Communications (PIMRC), New York: IEEE , 2011, p. 515-519Conference paper (Refereed)
    Abstract [en]

    This paper proposes a power estimation methodology which presents low complexity when implemented in hardware. Power estimation is done in digital and the radio signals are digitized using a 1-bit quantizer. An algorithm to estimate power is proposed. Power estimation of the signal is done while varying the threshold of the 1-bit quantizer. It is also shown that the proposed architecture can be used to estimate power of wideband radio channels.

  • 16.
    Dwivedi, Satyam
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    De Angelis, Alessio
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Scheduled UWB pulse transmissions for cooperative localization2012In: Ultra-Wideband (ICUWB), 2012 IEEE International Conference on, IEEE , 2012, p. 6-10Conference paper (Refereed)
    Abstract [en]

    In this paper we have proposed a technique for cooperative localization where localization is done in distributive fashion without using any additional broadcast by nodes. The method relies on a fixed scheduled ultra-wideband (UWB) pulse transmissions by nodes in a predetermined way. The advantages of the proposed method is simpler hardware, comparatively less pulse transmission in the system hence energy efficient and faster update rate.

  • 17.
    Dwivedi, Satyam
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing.
    De Angelis, Alessio
    Zachariah, Dave
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Joint Ranging and Clock Parameter Estimation by Wireless Round Trip Time Measurements2015In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 33, no 11, p. 2379-2390Article in journal (Refereed)
    Abstract [en]

    In this paper, we develop a new technique for estimating fine clock errors and range between two nodes simultaneously by two-way time-of-arrival measurements using impulse-radio ultrawideband signals. Estimators for clock parameters and the range are proposed, which are robust with respect to outliers. They are analyzed numerically and by means of experimental measurement campaigns. The technique and derived estimators achieve accuracies below 1 Hz for frequency estimation, below 1 ns for phase estimation, and 20 cm for range estimation, at a 4-m distance using 100-MHz clocks at both nodes. Therefore, we show that the proposed joint approach is practical and can simultaneously provide clock synchronization and positioning in an experimental system.

  • 18.
    Dwivedi, Satyam
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Precise Clock Parameter Estimation and Ground Truth Capture for Clock Error Measurements using FPGAs2014In: 2014 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control and Communication (ISPCS), IEEE , 2014, p. 83-86Conference paper (Refereed)
    Abstract [en]

    In this extended abstract we discuss and propose a mechanism to estimate clock parameters between two clocks using TDC. Simultaneously, we have proposed a ground truth capture methodology for clock error measurements. In particular, we have proposed an accurate way of measuring clock phase ground truth at any instant in time using delay lines in FPGA. Accuracy of clock phase ground truth measurement can be up to 16 ps. We have estimated clock parameters from measurements and have compared it with clock ground truth obtained using suggested methods. Relative frequency errors are estimated with RMSE of 0.46 Hz and phase error is estimated with RMSE of 0.29 ns.

  • 19.
    Dwivedi, Satyam
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Zachariah, Dave
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    De Angelis, Alessio
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Cooperative Decentralized Localization Using Scheduled Wireless Transmissions2013In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 17, no 6, p. 1240-1243Article in journal (Refereed)
    Abstract [en]

    In this letter we develop a solution for decentralized localization of transceiving nodes in wireless networks. By exploiting a common transmission schedule, this is achieved without any additional communication and dispels the need for synchronized nodes. We derive the Cramer-Rao bounds for the solution and formulate two practical estimators for localization. Finally, the solution and estimators are tested in numerical experiments.

  • 20.
    Gholami, Mohammad Reza
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Dwivedi, Satyam
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Jansson, Magnus
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Ranging without time stamps exchanging2015In: ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings, IEEE conference proceedings, 2015, p. 3981-3985Conference paper (Refereed)
    Abstract [en]

    We investigate the range estimate between two wireless nodes without time stamps exchanging. Considering practical aspects of oscillator clocks, we propose a new model for ranging in which the measurement errors include the sum of two distributions, namely, uniform and Gaussian. We then derive an approximate maximum likelihood estimator (AMLE), which poses a difficult global optimization problem. To avoid the difficulty in solving the complex AMLE, we propose a simple estimator based on the method of moments. Numerical results show a promising performance for the proposed technique.

  • 21. Pasku, Valter
    et al.
    De Angelis, Alessio
    Moschitta, Antonio
    Carbone, Paolo
    Nilsson, John-Olof
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Dwivedi, Satyam
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing.
    A Magnetic Ranging Aided Dead-Reckoning Indoor Positioning System for Pedestrian Applications2016In: 2016 IEEE INTERNATIONAL INSTRUMENTATION AND MEASUREMENT TECHNOLOGY CONFERENCE PROCEEDINGS, IEEE conference proceedings, 2016, p. 1526-1531Conference paper (Refereed)
    Abstract [en]

    This paper investigates the applicability of a developed magnetic ranging and positioning system (MPS) as a support for a dead reckoning inertial navigation system for pedestrian applications. The integrated system combines the complementary properties of the separate systems, operating over long periods of time and in cluttered indoor areas with partial non-line-of-sight conditions. The obtained results show that the proposed approach can effectively improve the coverage area of the MPS and the operation time with bounded errors of the dead reckoning based system.

  • 22. Pasku, Valter
    et al.
    De Angelis, Alessio
    Moschitta, Antonio
    Carbone, Paolo
    Nilsson, John-Olof
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Signal Processing.
    Dwivedi, Satyam
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Signal Processing.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. KTH, School of Electrical Engineering (EES), Signal Processing.
    A Magnetic Ranging-Aided Dead-Reckoning Positioning System for Pedestrian Applications2017In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 66, no 5, p. 953-963Article in journal (Refereed)
    Abstract [en]

    This paper investigates the applicability of a developed Magnetic Positioning System (MPS) as a support for a dead-reckoning inertial navigation system (DR-INS) for pedestrian applications. The integrated system combines the complementary properties of the separate systems, operating over long periods of time and in cluttered indoor areas with partial nonline-of-sight conditions. The obtained results show that the proposed approach can effectively improve the coverage area of the MPS and the operation time with bounded errors of the DR-INS. In particular, a solution that provides bounded position errors of 1-2 m over significantly long periods of time up to 45 min, in realistic indoor environments, is demonstrated. Moreover, system applicability is also shown in those scenarios where arbitrary orientations of the MPS mobile node are considered and an MPS position estimate is not available due to less than three distance measurements.

  • 23. Sankaragomathi, K.A.
    et al.
    Sahoo, Manodipan
    Dwivedi, Satyam
    Department of Electrical Communication Engineering, Indian Institute of Science.
    Amrutur, Bharadwaj
    Optimal power and noise allocation for analog and digital sections of a low power radio receiver2008In: ISLPED'08: 13th ACM/IEEE International Symposium on Low Power Electronics and Design, 2008, p. 271-276Conference paper (Refereed)
    Abstract [en]

    We determine the optimal allocation of power between the analog and digital sections of an RF receiver while meeting the BER constraint. Unlike conventional RF receiver designs, we treat the SNR at the output of the analog front end (SNRAD) as a design parameter rather than a specification to arrive at this optimal allocation. We first determine the relationship of the SNRAD to the resolution and operating frequency of the digital section. We then use power models for the analog and digital sections to solve the power minimization problem. As an example, we consider a 802.15.4 compliant low-IF receiver operating at 2.4 GHz in 0.13 μm technology with 1.2 V power supply. We find that the overall receiver power is minimized by having the analog front end provide an SNR of 1.3dB and the ADC and the digital section operate at 1-bit resolution with 18MHz sampling frequency while achieving a power dissipation of 7mW.

  • 24.
    Yajanarayana, Vijaya
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Dwivedi, Satyam
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing.
    IR-UWB Detection and Fusion Strategies using Multiple Detector TypesManuscript (preprint) (Other academic)
    Abstract [en]

    Optimal detection of ultra wideband (UWB) pulses in a UWB transceiver employing multiple detector types is proposed and analyzed in this paper. We propose several fusion techniques for fusing decisions made by individual IR-UWB detectors. We assess the performance of these fusion techniques for commonly used detector types like matched filter, energy detector and amplitude detector. In order to perform this, we derive the detection performance equation for each of the detectors in terms of false alarm rate, shape of the pulse and number of UWB pulses used in the detection and apply these in the fusion algorithms. We show that the performance can be improved approximately by 4 dB in terms of signal to noise ratio (SNR) for perfect detectability of a UWB signal in a practical scenario by fusing the decisions from individual detectors.

  • 25.
    Yajanarayana, Vijaya
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Dwivedi, Satyam
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Multi Detector Fusion of Dynamic TOA Estimation using Kalman Filter2016Conference paper (Other academic)
    Abstract [en]

    In this paper, we propose fusion of dynamic TOA (time of arrival) from multiple non-coherent detectors like energy detectors operating at sub-Nyquist rate through Kalman filtering. We also show that by using multiple of these energy detectors, we can achieve the performance of a digital matched filter implementation in the AWGN (additive white Gaussian noise) setting. We derive analytical expression for number of energy detectors needed to achieve the matched filter performance. We demonstrate in simulation the validity of our analytical approach. Results indicate that number of energy detectors needed will be high at low SNRs and converge to a constant number as the SNR increases. We also study the performance of the strategy proposed using IEEE 802.15.4a CM1 channel model and show in simulation that two sub-Nyquist detectors are sufficient to match the performance of digital matched filter.

  • 26.
    Yajnanarayana, Vijaya
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Dwivedi,, Satyam
    KTH, School of Electrical Engineering (EES), Signal Processing.
    De Angelis, Alessio
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Design of impulse radio UWB transmitter for short range communications using PPM signals2013In: IEEE International Conference on Electronics, Computing and Communication Technologies (CONECCT), 2013, IEEE conference proceedings, 2013, p. 1-4Conference paper (Refereed)
    Abstract [en]

    There are several practical challenges in designing an ultra wideband (UWB) device for communication. From the physical layer perspective, signaling technique should be optimally designed to work in synergy with the underneath hardware to achieve maximum performance. In this paper we propose a new cost effective hardware architecture for UWB communication and propose a variant of pulse position modulation (PPM) method which achieves maximum bit rate under the practical constraints imposed by UWB hardware.

  • 27.
    Yajnanarayana, Vijaya
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Dwivedi, Satyam
    KTH, School of Electrical Engineering (EES), Signal Processing.
    De Angelis, Alessio
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Spectral efficient IR-UWB communication design for low complexity transceivers2014In: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2014, no 158Article in journal (Refereed)
    Abstract [en]

    Ultra wideband (UWB) radio for communication has several challenges. From the physical layer perspective, asignaling technique should be optimally designed to work in synergy with the underneath hardware to achievemaximum performance. In this paper, we propose a variant of pulse position modulation (PPM) for physical layersignaling, which can achieve raw bitrate in excess of 150 Mbps on a low complexity in-house developed impulseradio UWB platform. The signaling system is optimized to maximize bitrate under practical constraints of lowcomplexity hardware and regulatory bodies. We propose a detector and derive its theoretical performance boundsand compare the performance in simulation in terms of symbol error rates (SER). Modifications to the signaling, whichcan increase the range by 4 times with a slight increase in hardware complexity, is proposed. Detectors for thismodification and a comparative study of the performance of the proposed UWB physical layer signaling schemes interms of symbol error rates are discussed.

  • 28.
    Yajnanarayana, Vijaya
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Dwivedi, Satyam
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Design of impulse radio UWB transmitter with improved range performance using PPM signals2014In: 2014 IEEE International Conference on Electronics, Computing and Communication Technologies (IEEE CONECCT), IEEE Computer Society, 2014, p. 1-5Conference paper (Refereed)
    Abstract [en]

    There are several practical challenges in designing an ultra wideband (UWB) device for communication. From the physical layer signaling perspective it is important to avoid the strong peaks in the transmitted signal to fully exploit the regulatory bodies power constraint requirements. This will result in increased range performance for the sensors. Design of the transmit impulse radio (IR) UWB signals under the practical constraints of hardware and regulatory body is a critical optimization issue in the UWB system design. In this paper, we propose a IR-UWB signaling, which is a variant of pulse position modulation (PPM) method and achieves an increased range performance under the practical constraints of hardware and Federal Communications Commission (FCC) regulations.

  • 29.
    Yajnanarayana, Vijaya
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Dwivedi, Satyam
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    IR-UWB detection and fusion strategies using multiple detector types2016In: IEEE Wireless Communications and Networking Conference, WCNC, Institute of Electrical and Electronics Engineers (IEEE), 2016, article id 7565140Conference paper (Refereed)
    Abstract [en]

    Optimal detection of ultra wideband (UWB) pulses in a UWB transceiver employing multiple detector types is proposed and analyzed in this paper. To enable the transceiver to be used for multiple applications, the designers have different types of detectors such as energy detector, amplitude detector, etc., built in to a single transceiver architecture. We propose several fusion techniques for fusing decisions made by individual IR-UWB detectors. In order to get early insight into theoretical achievable performance of these fusion techniques, we assess the performance of these fusion techniques for commonly used detector types like matched filter, energy detector and amplitude detector under Gaussian assumption. These are valid for ultra short distance communication and in UWB systems operating in millimeter wave (mmwave) band with high directivity gain. In this paper, we utilize the performance equations of different detectors, to device distinct fusion algorithms. We show that the performance can be improved approximately by 4 dB in terms of signal to noise ratio (SNR) for high probability of detection of a UWB signal (> 95%), by fusing decisions from multiple detector types compared to a standalone energy detector, in a practical scenario.

  • 30.
    Yajnanarayana, Vijaya
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Dwivedi, Satyam
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Multi Detector Fusion of Dynamic TOA hstimation using Kalman Filter2016In: 2016 IEEE International Conference on Communications (ICC), Institute of Electrical and Electronics Engineers (IEEE), 2016Conference paper (Refereed)
    Abstract [en]

    In this paper we propose fusion of dynamic time of arrival (TOA) from multiple low complexity detectors like energy detectors operating at sub-Nyquist rate through Kalman filtering. We show that by having a multi-channel sub-Nyquist receiver with each channel having an energy detector can match the performance of a single channel digital receiver with matched filter. We derive analytical expression for number of sub-Nyquist energy detector channels needed to achieve the performance of digital implementation with matched filter and demonstrate in simulation the validity of our analytical approach. Results indicate that number of energy detectors needed will he high at low SNRs and converge to a constant number as the SNR increases. We also study the performance of the proposed strategy using IEEE 802.15.4a CM1 multipath channel model and show in simulation that two sub-Nyquist detectors are sufficient to match the performance of digital matched filter.

  • 31.
    Yajnanarayana, Vijaya
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Magnusson, Klas E. G.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Brandt, Rasmus
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Dwivedi, Satyam
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Optimal Scheduling for Interference Mitigation by Range Information2017In: IEEE Transactions on Mobile Computing, ISSN 1536-1233, E-ISSN 1558-0660, Vol. 16, no 11, p. 3167-3181Article in journal (Refereed)
  • 32.
    Zachariah, Dave
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    De Angelis, Alessio
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Dwivedi, Satyam
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Schedule-based sequential localization in asynchronous wireless networks2014In: EURASIP Journal on Advances in Signal Processing, ISSN 1687-6172, E-ISSN 1687-6180, Vol. 2014, no 1, p. 16-Article in journal (Refereed)
    Abstract [en]

    In this paper, we consider the schedule-based network localization concept, which does not requiresynchronization among nodes and does not involve communication overhead. The concept makesuse of a common transmission sequence, which enables each node to perform self-localization andto localize the entire network, based on noisy propagation-time measurements. We formulate theschedule-based localization problem as an estimation problem in a Bayesian framework. This pro-vides robustness with respect to uncertainty in such system parameters as anchor locations and timing devices. Moreover, we derive a sequential approximate maximum a posteriori (AMAP) estimator.The estimator is fully decentralized and copes with varying noise levels. By studying the fundamentalconstraints given by the considered measurement model, we provide a system design methodology which enables a scalable solution. Finally, we evaluate the performance of the proposed AMAPestimator by numerical simulations emulating an impulse-radio ultra-wideband (IR-UWB) wireless network.

  • 33.
    Zachariah, Dave
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    De Angelis, Alessio
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Dwivedi, Satyam
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Self-Localization of Asynchronous Wireless Nodes With Parameter Uncertainties2013In: IEEE Signal Processing Letters, ISSN 1070-9908, E-ISSN 1558-2361, Vol. 20, no 6, p. 551-554Article in journal (Refereed)
    Abstract [en]

    We investigate a wireless network localization scenario in which the need for synchronized nodes is avoided. It consists of a set of fixed anchor nodes transmitting according to a given sequence and a self-localizing receiver node. The setup can accommodate additional nodes with unknown positions participating in the sequence. We propose a localization method which is robust with respect to uncertainty of the anchor positions and other system parameters. Further, we investigate the Cramer-Rao bound for the considered problem and show through numerical simulations that the proposed method attains the bound.

1 - 33 of 33
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