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Vijay Kumar Chakka

Bio: Vijay Kumar Chakka is an academic researcher from Shiv Nadar University. The author has contributed to research in topic(s): Orthogonal frequency-division multiplexing & MIMO. The author has an hindex of 6, co-authored 49 publication(s) receiving 201 citation(s). Previous affiliations of Vijay Kumar Chakka include Indian Institute of Chemical Technology & Dhirubhai Ambani Institute of Information and Communication Technology.

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Papers
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Journal ArticleDOI
Abstract: One of the main issues of orthogonal frequency division multiplexing (OFDM) is the high peak-to-average power ratio (PAPR) of the transmitted signal which adversely affects the complexity of power amplifiers. The selected mapping (SLM) technique is one of the promising PAPR reduction techniques for OFDM. In this reported work, rows of normalised Riemann matrices are selected as phase sequence vectors for the SLM technique. MATLAB simulations show PAPR reduction of around 2.3 dB using the proposed method compared with methods reported in the literature.

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79 citations


Proceedings ArticleDOI
01 Dec 2009-
Abstract: Selected Mapping (SLM) technique is one of the promising PAPR reduction techniques for Orthogonal Frequency Division Multiplexing (OFDM). But this reduction technique results in a huge amount of computation complexity which is costly and time consuming. In this paper, Riemann sequences are used as a phase vectors along with the thresholding of the power amplifier(PA). The default index of the phase sequence is used to reduce the computational complexity of SLM technique. The default index of a phase sequence refers to the starting index for the phase vectors in the SLM scheme. This index is derived from the experimentation results. The Matlab simulations show that the complexity has been reduced by 98 percent if the threshold value of PA is around 3.0dB. Index Terms—OFDM, PAPR, Complexity, Riemann Sequence, Error function, Default Index.

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18 citations


Proceedings ArticleDOI
01 Dec 2016-
TL;DR: This work proposes an approach using Ramanujan periodic transform for reducing PLI and is tested on a subject data from MIT-BIH Arrhythmia database.

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Abstract: Suppression of interference from narrowband frequency signals play vital role in many signal processing and communication applications. A transform based method for suppression of narrow band interference in a biomedical signal is proposed. As a specific example Electrocardiogram (ECG) is considered for the analysis. ECG is one of the widely used biomedical signal. ECG signal is often contaminated with baseline wander noise, powerline interference (PLI) and artifacts (bioelectric signals), which complicates the processing of raw ECG signal. This work proposes an approach using Ramanujan periodic transform for reducing PLI and is tested on a subject data from MIT-BIH Arrhythmia database. A sum (E) of Euclidean error per block (e i ) is used as measure to quantify the suppression capability of RPT and notch filter based methods. The transformation is performed for different lengths (N), namely 36, 72, 108, 144, 180. Every doubling of N-points results in 50% reduction in error (E).

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10 citations


Proceedings ArticleDOI
Arun Joy1, Vijay Kumar Chakka1Institutions (1)
24 Mar 2011-
TL;DR: This paper presents a MIMO two-way relaying scheme where the transceiver filter at the Relay Station (RS) processes the data using Le least Mean Square Algorithm (LMS) and Normalized Least Mean Square (NLMS) algorithm.

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Abstract: This paper presents a MIMO two-way relaying scheme where the transceiver filter at the Relay Station (RS) processes the data using Least Mean Square Algorithm (LMS) and Normalized Least Mean Square (NLMS) algorithm. The relaying technique used is Amplify and Forward scheme (AF). Channel State Information (CSI) is assumed to be available only at the RS. So the transmit and receive processing are both done at the RS. The data at the two nodes S 1 and S 2 is Quadrature Phase Shift Keying (QPSK) modulated. The metrics considered for performance comparison of the LMS/NLMS transceiver filter is Mean Square Error (MSE) and Bit Error Rate (BER). The computer simulations are performed using MATLAB.

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8 citations


Journal ArticleDOI
TL;DR: A Fast Array Multichannel Two-Dimensional Recursive Least Square (FAM 2D-RLS) adaptive filter is proposed for estimating an OFDM channel in frequency domain that makes use of the shift structure of the input data vector.

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Abstract: In this paper a Fast Array Multichannel Two-Dimensional Recursive Least Square (FAM 2D-RLS) adaptive filter is proposed for estimating an OFDM channel in frequency domain. This filter makes use of the shift structure of the input data vector. Thus the computational cost of the classical RLS filter which is O(M 2) is reduced to O(M) for each iteration where M is the order of the filter. In order to ensure numerical stability in finite precision, we make use of array-based methods for implementing FAM 2D-RLS. The adaptive filters illustrated in the standard literature consist of a weight vector and desired data as a scalar. But in our scenario of OFDM channel estimation the weight is a matrix while the desired data are a vector. Hence the algorithm for the matrix form of FAM-2D RLS and its steady state equations are derived. Numerical stability, steady state and convergence performance are verified using MATLAB simulations.

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7 citations


Cited by
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Book
01 Jan 2003-
TL;DR: Comprehensive in scope, and gentle in approach, this book will help you achieve a thorough grasp of the basics and move gradually to more sophisticated DSP concepts and applications.

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Abstract: From the Publisher: This is undoubtedly the most accessible book on digital signal processing (DSP) available to the beginner. Using intuitive explanations and well-chosen examples, this book gives you the tools to develop a fundamental understanding of DSP theory. The author covers the essential mathematics by explaining the meaning and significance of the key DSP equations. Comprehensive in scope, and gentle in approach, the book will help you achieve a thorough grasp of the basics and move gradually to more sophisticated DSP concepts and applications.

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107 citations


Book ChapterDOI
01 Jan 2007-
Abstract: A maximum likelihood (ML) estimator for digital sequences disturbed by Gaussian noise, intersymbol interference (ISI) and interchannel interference (ICI) is derived. It is shown that the sampled outputs of the multiple matched filter (MMF) form a set of sufficient statistics for estimating the input vector sequence. Two ML vector sequence estimation algorithms are presented. One makes use of the sampled output data of the multiple whitened matched filter and is called the vector Viterbi algorithm. The other one is a modification of the vector Viterbi algorithm and uses directly the sampled output of the MMF. It appears that, under a certain condition, the error performance is asymptotically as good as if both ISI and ICI were absent.

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70 citations


Journal ArticleDOI
TL;DR: A new methodology based on the Fourier decomposition method (FDM) to separate both BW and PLI simultaneously from the recorded ECG signal and obtain clean ECG data and has low computational complexity which makes it suitable for real-time pre-processing of ECG signals.

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Abstract: Baseline wander (BW) and power-line interference (PLI) tend to occur in every recorded electrocardiogram (ECG) signal and can significantly deteriorate the quality of the signal. They need to be separated from the ECG signal to facilitate an accurate diagnosis of the patient. In this paper, we propose a new methodology based on the Fourier decomposition method (FDM) to separate both BW and PLI simultaneously from the recorded ECG signal and obtain clean ECG data. The proposed method employs either of discrete Fourier transform (DFT) or discrete cosine transform (DCT) in order to process the signal. Key DFT/DCT coefficients relating to BW and PLI are identified and then suppressed using optimally designed FDM based on a zero-phase filtering approach. The effectiveness of our method is validated on the MIT-BIH Arrhythmia database. Simulation results clearly demonstrate that the proposed method performs superior in comparison to the existing state-of-the-art techniques at different levels of signal to noise ratio power (SNR). Moreover, this method has low computational complexity which makes it suitable for real-time pre-processing of ECG signals.

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43 citations


Journal ArticleDOI
Ahmad M. Rateb, Mohamed Labana1Institutions (1)
25 Jan 2019-IEEE Access
TL;DR: This paper proposes a low-complexity technique for PAPR reduction based on linear scaling of a portion of signal coefficients by an optimal factor that has a very good potential for practical application in current and future OFDM-based systems, especially those which employ a very large number of subcarriers.

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Abstract: Orthogonal frequency division multiplexing (OFDM) is an efficient multi-carrier modulation technique that underlies most of the current and probably future high-speed wireless communication systems. However, the OFDM waveform is characterized by a high peak-to-average power ratio (PAPR), especially when a large number of subcarriers are used. A high PAPR is a major waveform defect since it leads to non-linear distortion when passing through the transmitter’s power amplifier. Most of the PAPR reduction techniques found in the literature reduce the PAPR mainly at the cost of either excessive computational complexity or degrading the transmission bit error rate (BER). We propose a low-complexity technique for PAPR reduction based on linear scaling of a portion of signal coefficients by an optimal factor. This paper is backed up by the extensive analysis of various performance metrics, which leads to optimal choices of key parameters and hence maximum achievable gains. The analytic and simulated results show that the proposed technique is capable of reducing the PAPR effectively with negligible effect on BER in return for a slight reduction in data rate. For example, for 1024 subcarriers, the PAPR can be reduced from 13 dB to below 7.4 or 6.9 dB, in return for only 1% or 2% reduction in data rate, respectively. In addition, the achievable PAPR varies very slightly in response to increasing the number of subcarriers. This offers a highly competitive and flexible tradeoff compared with those provided by current techniques found in the literature. Therefore, this technique has a very good potential for practical application in current and future OFDM-based systems, especially those which employ a very large number of subcarriers, such as LTE, DVB-T2, and 5G systems.

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26 citations


Journal ArticleDOI
TL;DR: Simulation results show that the proposed schemes can obtain significant PAPR reduction performance with that of ordinary SLM techniques.

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Abstract: One of main disadvantage of OFDM is high peak-to-average power ratio (PAPR). In this paper, two effective PAPR reduction schemes are proposed. These techniques combine DCT and SLM techniques. The scheme 1 is composed of the DCT followed by SLM technique, and the DCT is used followed by conventional SLM in proposed scheme 2. Simulation results show that the proposed schemes can obtain significant PAPR reduction performance with that of ordinary SLM techniques.

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19 citations


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Performance
Metrics

Author's H-index: 6

No. of papers from the Author in previous years
YearPapers
20214
20206
20197
20174
20164
20152

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