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  • 1. Ahmed, Zakir
    et al.
    Bhardwaj, Krishna
    Krishnan, Ramesh
    Yajnanarayana, Vijaya
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Estimation of Sample Clock Frequency Offset Using Error Vector Magnitude2011Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A low complexity system and method for operating a receiver in order to estimate an offset between the actual sample clock rate 1/TS' of a receiver and an intended sample clock rate 1/TS. The receiver captures samples of a received baseband signal at the rate 1/TS', operates on the captured samples to generate an estimate for the clock rate offset, and fractionally resamples the captured samples using the clock rate offset. The resampled data represents an estimate of baseband symbols transmitted by the transmitter. The action of operating on the captured samples involves computing an error vector signal and then estimating the clock rate offset using the error vector signal. The error vector signal may be computed in different ways depending on whether or not carrier frequency offset and carrier phase offset are assumed to be present in the received baseband signal.

  • 2. Ahmed, Zakir
    et al.
    Yajnanarayana, Vijaya
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Blind mechanism for the joint estimation of frequency offset and phase offset for QAM modulated signals2010Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A mechanism for jointly correcting carrier phase and carrier frequency errors in a demodulated signal. A computer system may receive samples of a baseband input signal (resulting from QAM demodulation). The computer system may compute values of a cost function J over a grid in a 2D angle-frequency space. A cost function value J(theta,omega) is computed for each point (theta,omega) in the grid by (a) applying a phase adjustment of angle theta and a frequency adjustment of frequency omega to the input signal; (b) performing one or more iterations of the K-means algorithm on the samples of the adjusted signal; (c) generated a sum on each K-means cluster; and (d) adding the sums. The point (thetae,omegae) in the 2D angle-frequency space that minimizes the cost function J serves an estimate for the carrier phase error and carrier frequency error.; The estimated errors may be used to correct the input signal.

  • 3. Ahmed, Zakir
    et al.
    Yajnanarayana, Vijaya
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Maximizing the Viterbi Winning Path Metric to Estimate Carrier Frequency and Phase Offsets in Continuous Phase Modulated Signals2012Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A system and method for estimating carrier frequency offset Δf and carrier phase offset φ0 inherent in a received CPM signal. Samples of a continuous phase modulated (CPM) signal are received. A maximum of an objective function J is determined over a two-dimensional region parameterized by frequency offset v and phase offset w. The coordinates vmax and wmax of a maximizing point in the region represent estimates of the carrier frequency offset Δf and the carrier phase offset φ0. To evaluate the objective function J at a point (v, w), apply a frequency shift of amount −v and a phase shift of amount −w to the received samples to obtain modified samples, and perform Viterbi demodulation on the modified samples to obtain a winning path metric value at a final time. The winning path metric value is the objective function value J(v, w). 

  • 4.
    Ahmed, Zakir
    et al.
    Motorola India Electron. Ltd., Bangalore .
    Yajnanarayana, Vijaya
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Sancheti, Nirmal Kumar
    A time domain based efficient block decision algorithm for audio coders2007In: International Symposium on Communications and Information Technologies, 2007. ISCIT '07, IEEE Press, 2007, p. 1077-1081Conference paper (Refereed)
    Abstract [en]

    In typical audio encoders the block decision is done either using time-domain techniques like energy computation or frequency domain techniques like temporal noise shaping (TNS) [1], [2]. The time-domain energy computation based decisions are less effective for detecting many of the stringent scenarios presented by test cases like castanets and fatboy. The frequency domain based algorithms have better decision making capabilities, however they are inherently complex as they require the computation of the FFT, additionally in case of TNS the computation of LPC (Linear Prediction coding) in the frequency domain. An improved time-domain technique with better block decision capability compared to TNS and with lesser computational complexity is proposed in this paper.

  • 5. Girish, V V
    et al.
    Govindan, V K
    Baig, Shakeel
    Yajnanarayana, Vijaya
    Nokia Siemens Networks-DC.
    A Novel Initial Ranging Algorithm for mobile WiMAX (802.16e)2010In: International Journal of Computer Applications, ISSN 0975-8887, E-ISSN 0975-8887, Vol. 1, no 3, p. 95-100Article in journal (Refereed)
    Abstract [en]

    Initial ranging process plays an important role in the mobile worldwide interoperability for microwave access (WiMAX) standard (IEEE 802.16e). Timing offset adjustment, power offset calculation and synchronization between the base station and all the users within a cell are achieved during the initial ranging process. A comparative study of existing and a novel ranging algorithm is proposed in this paper. Most of the current ranging algorithms do not take in to account the interference created by the ranging codes sent by other ranging users in an Orthogonal Frequency Division Multiple Access (OFDMA) setup [2][4][5][7]. The novel ranging method cancels the interference created due to the other raging codes in the ranging area. The simulation results indicate a significant improvement in performance under practical scenarios.

  • 6. Rupp, Craig
    et al.
    Valdes, Gerardo Orozco
    Ahmed, Zakir
    Yajnanarayana, Vijaya
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Unit Testing and Analysis Using a Stored Reference Signal2014Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    Method and system for a test process. The method may include performing tests on one or more units under test (UUTs). At least one test on one or more UUTs may be performed. A signal may be acquired from the UUT. A reference signal may be retrieved. The reference signal may be derived from a transmitted signal characteristic of the UUT. The signal may be analyzed with respect to the reference signal. Results, useable to characterize the one or more UUTs, from performing the at least one test on the one or more UUTs may be stored. The reference signal may be derived from an initial test and may be stored for subsequent retrieval. A respective reference signal may be retrieved for all UUTs of the one or more UUTs for a respective test. The signal may be a radio frequency signal. The UUT may be a wireless mobile device. 

  • 7. Sartaj, Chaudhary
    et al.
    Yajnanarayana, Vijaya
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Zakir, Ahmed
    Blind Mechanism for Demodulating Offset QPSK Signals in the Presence of Carrier Phase Error2012Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A computer-implemented system and method for blind demodulation of an offset QPSK input signal, involving repeatedly performing a set of operations, including: (a) applying a phase correction to the input signal based on an estimate of a carrier phase offset of the input signal to obtain a first modified signal; (b) shifting a quadrature component of the first modified signal by half a symbol period relative to an inphase component to obtain a second modified signal; (c) extracting a first sequence of symbols from the second modified signal, where the extraction includes estimating a symbol timing offset from the second modified signal; (d) performing hard-decision demodulation on the first sequence of symbols to obtain a second sequence of reference symbols; (e) computing a phase difference between the first sequence of symbols and second sequence of reference symbols; and (f) updating the carrier phase offset estimate using the phase difference. 

  • 8.
    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.

  • 9.
    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.

  • 10.
    Yajnanarayana, Vijaya
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Ahmed, Zakir
    Novel method for blind constellation detection using template based classifier for quadrature digital modulation schemes.2011In: IEEE 2011 10th International Conference on Electronic Measurement and Instruments, ICEMI 2011, 2011, p. 1-4Conference paper (Refereed)
    Abstract [en]

    Template based classifiers are very popular classifiers in biomedical and computer vision area. In computer vision they are typically used to understand or classify the scenes captured by camera. In biomedical field they are typically used to provide non-intrusive disease identification. For example to classify a tissue samples as cancerous or not. In this paper we apply the learnings of this area to device an algorithm for automatic modulation detection problem. Automatic modulation detection problem in communication receivers involves auto detecting the modulation scheme from the received samples at the communication receiver without the prior knowledge of the encoded modulation scheme. The method can efficiently recognize almost all quadrature digital modulation schemes and the accuracy rate is over 95% at the SNRs of 4.5 dB with as low as 512 bits. The performance of this algorithm is evaluated using simulations on LabVIEW.

  • 11.
    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.

  • 12.
    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.

  • 13.
    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.

  • 14.
    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.

  • 15.
    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.

  • 16.
    Yajnanarayana, Vijaya
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Joint Estimation of TOA and PPM Symbols Using Sub-Nyquist Sampled IR-UWB Signal2017In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 21, no 4, p. 949-952Article in journal (Refereed)
    Abstract [en]

    Impulse radio ultra wideband (UWB) signals are used in various applications which require joint localization and communication. Due to the large bandwidth of the UWB signal, the estimation of time of arrival (TOA) and data symbols requires high sampling rates. This letter describes a sub-Nyquist rate receiver, which can jointly estimate TOA and data symbols. We first represent the received UWB signal in a new domain in which it is sparse. Then, we design physical layer waveforms and estimation algorithms to exploit this sparsity for joint estimation of TOA and pulse position modulation data symbols. The performance of the receiver is compared against the maximum likelihood (ML)-based receiver using an IEEE 802.15.4a CM1 line of sight UWB channel model. The proposed algorithm yields performance similar to the ML-based algorithms with only a fraction of sampling rate at high SNRs (> 25 dB).

  • 17.
    Yajnanarayana, Vijaya
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Performance evaluation of IR-UWB detectors and fusion techniques for UWB transceiver platforms2018In: International Journal of Ultra Wideband Communications and Systems, ISSN 1758-728X, Vol. 3, no 4, p. 177-191Article in journal (Refereed)
    Abstract [en]

    In this paper, we analyse the performance of a multi-pulse impulse radio based ultra-wideband (IR-UWB) detector in an AWGN setting and provide different fusion strategies for fusing these detector outputs. To enable the transceiver to be used for multiple applications, the designers have different types of detectors such as energy detectors, amplitude detectors, etc., built in to a single transceiver architecture. In this paper, we derive the detection performance equation for commonly used 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 by approximately 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.

  • 18.
    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)
  • 19.
    Yajnanarayana, Vijaya
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Magnusson, Klas E. G.
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Brandt, Rasmus
    Dwivedi,, Satyam
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Händel, Peter
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Optimal Scheduling for Interference Mitigation by Range InformationManuscript (preprint) (Other academic)
    Abstract [en]

    This paper describes several algorithms for generating an optimal schedule for multiple access on a shared channel by utilizing range information in a fully connected network. We also provide detailed analysis for the proposed algorithms in terms of their complexity, convergence, and effect of non-idealities in the network. The performance of the proposed schemes are compared with non-aided methods to quantify the benefits of using the range information in the communication. We argue that the proposed techniques yield significant benefits as the number of nodes in the network increases. We provide simulation results in support of the claim. The proposed methods indicate that the throughput can be increased on average by 3-10 times for typical network configurations.

  • 20.
    Yajnanarayana, Vijaya Parampalli
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Ultra Wideband: Communication and Localization2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The first part of this thesis develops methods for UWB communication. To meet the stringent regulatory body constraints, the physical layer signaling technique of the UWB transceiver should be optimally designed. We propose two signaling schemes which are variants of pulse position modulation (PPM) signaling for impulse radio (IR) UWB communication. We also discuss the detectors for the signaling schemes and evaluate the performance of these detectors.  IR-UWB can be used for precise range measurements as it provides a very high time resolution. This enables accurate time of arrival (TOA) estimations from which precise range values can be derived. We propose methods which use range information to arrive at optimal schedules for an all-to-all broadcast problem. Results indicate that throughput can be increased on average by three to ten times for typical network configurations compared to the traditional methods. Next, we discuss hypothesis testing in the context of UWB transceivers. We show that, when multiple detector outputs from a hardware platform are available, fusing the results from them can yield better performance in hypothesis testing than relying on a single detector output. In the second part of this thesis, the emphasis is placed on localization and joint estimation of location and communication parameters. Here, we focus on estimating the TOA of the signal. The wide bandwidth of the UWB signal requires high speed analog to digital converts (ADC) which makes the cost of the digital transceivers prohibitively high. To address this problem, we take two different strategies. In the first approach, we propose a multichannel receiver with each channel having a low-cost energy detector operating at a sub-Nyquist rate. In the second approach, we consider a compressive sampling based technique. Here, we propose a new acquisition front end, using which the sampling rate of the ADC can be significantly reduced. We extended the idea of compressive sampling based TOA estimation towards joint estimation of TOA and PPM symbols. Here, two signaling methods along with the algorithms are proposed based on the dynamicity of the target. They provide similar performance to the ML based estimation, however with a significant savings in the ADC resources.

  • 21.
    Yajnanarayana, Vijaya
    et al.
    Raman Research Institute, Bangalore. India.
    Rukmongathan, Temkar
    A Simple Controller for displaying Restricted Patterns On RMS Responding LCDs1999In: Society for Information Display Journal, p. 234-237Article in journal (Refereed)
    Abstract [en]

    A controller for displaying restricted patterns inpassive matrix LCDs will be presented. Hardwarecomplexity and the computational time forgenerating column signals are reduced considerablyby using serial arithmetic directly from digitisedsamples and hence eliminating the frame buffer inmulti-line addressing techniques.

  • 22.
    Yajnanarayana, Vijaya
    et al.
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Subramaniyan, Raghavan
    A Technique to Improve Performance of MPEG/H264 Video Decoder for Low Motion Video Applications using Vector Processor2005Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    Motion Compensation for video decoding in standards like MPEG and H.264 typically take more than 50% of the computational time, a new technique is proposed to speed up this process for low motion video sequence. This technique can be primarily employed for systems which have vector processors as video decode accelerators. The typical gain using this technique on an ideal vector processor can be more than 50% for a low motion video sequence. An ideal vector processor satisfies the below equation.

  • 23.
    Yajnanarayana, Vijaya
    et al.
    Motorola India Electron. Ltd., Bangalore.
    Subramaniyan, Raghavan
    Schuette, Michael A
    Techniques to improve motion compensation performance of H264 video decoder using a vector processor2007In: IEEE  International Symposium on Communications and Information Technologies, IEEE Press, 2007, p. 1082-1087Conference paper (Refereed)
    Abstract [en]

    Motion Compensation for video decoding in standards like H.264 requires significant amount of computation. This is primarily because of H.264 six-tap FIR filtering for sub-sample computation. These algorithms typically take more than 50% of the computational time on a RISC processor like ARM. Novel algorithms proposed through this paper can be employed for systems which use vector processors as video decode accelerators to accelerate this process. The proposed algorithms are implemented on H264 video decode system with ARM9 host-processor and RSVP vector processor as an accelerator for key decode algorithms. By employing the proposed algorithms we were able to accelerate the motion compensation module by more than 4 times as compared to plain RISC implementation. This is achieved by efficiently vectorizing data on which FIR-filtering and reconstruction algorithm is operated on, together with optimal representation of FIR-filtering and reconstruction algorithm itself on vector processor.

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