Browsing by Author "Kulkarni, M."

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A compact dual-band rectenna for RF energy harvesting
(Institute of Electrical and Electronics Engineers Inc., 2019) Polaiah, G.; Kandasamy, K.; Kulkarni, M.
In this paper, a compact dual-band rectenna operating in the frequency range of 4.8-5.2 GHz (Wi-Fi) and 7.77.9 GHz has been proposed. The antenna dual-band is achieved at a feed length of 38 mm by varying the feed length. The dual-band rectifier is designed with the help of Villard voltage doubler circuit with single T-matching network. The proposed rectenna has been implemented by integrating the rectifier to the antenna. The simulation results of antenna, rectifier, and rectenna are performed individually. The antenna is fabricated, various parameters measured, and compared with the simulated results. The maximum measured power conversion efficiency (PCE) of rectifier and rectenna of 51.7 % and 48.5% have been obtained. Â© 2019 IEEE.
A dual-band modified quadrilateral square slotted rectenna for rf energy harvesting
(Springer, 2020) Polaiah, G.; Kandasamy, K.; Kulkarni, M.
A dual-band planar rectenna, consisting of a modified quadrilateral square slot antenna with rectangular microstrip patch connect to a 50Â Î© feed line to improve the impedance matching and a single-series diode configuration-based half-wave rectifying circuit for high conversion efficiency, operate in frequency bands of universal mobile telecommunication service UMTS (2.1Â GHz) and higher WLAN/Wi-Fi (5Â GHz), is proposed for RF energy harvesting and wireless power transmission. The inverted L-section transmission line is introduced between the diode and dc pass filter to eliminate the harmonics within the operating frequencies. The antenna is connected to the rectifying circuit by using a pair of 50Â Î© SMA coaxial connectors. The peak measured conversion efficiency of proposed rectenna is 59.4% achieved at the input power of âˆ’9.8Â dBm and optimized load resistance of 560Â Î©, respectively. Â© Springer Nature Singapore Pte Ltd 2020.
A novel hybrid scheme using MLE with pulse shaping for ICI cancellation in OFDM systems
(2012) Savitha, H.M.; Kulkarni, M.
Carrier frequency offset (CFO) in orthogonal frequency division multiplexing systems results in heavy degradation to the system performance. Pulse shaping and Maximum likelihood estimation (MLE) are two of the several techniques available in the literature for reducing the undesired effects caused by CFO using inter carrier interference (ICI) cancellation and CFO correction respectively. In this paper, we combine these two techniques to cancel ICI further, thereby achieving a better bit error rate (BER) performance than the BER achieved by either of the two above mentioned schemes. It has been shown that around 1.7 dB BER performance improvement could be achieved using the new hybrid scheme as compared to MLE technique with low pass filtering. Further, the hybrid scheme adopted in this work is less sensitive to CFO compared to pulse shaping scheme. Â© 2012 IEEE.
A novel method for jammer localization in large scale sensor networks
(2010) Rau, A.V.; Raghuvara, R.; Shashimohan, V.; Kulkarni, M.
Sensor networks, by their very nature, are vulnerable to network security threats, with Denial of Service by radio jamming being one of the most common. It is more useful to detect jamming reactively than to proactively avoid it. We describe a method of countering jamming wherein some nodes just outside the jammed region form groups and transmit their locations to the Base Station for localization. These nodes are downstream in the hop-count based gradient broadcast routing sense. We also estimate the exact position of the jammer using the centre of curvature method. Simulation results show that the error in estimation of the jammer location is as low as 1.03m, accurate enough for real-time response. Â©2010 IEEE.
A novel optimal fuzzy system for color image enhancement using bacterial foraging
(Institute of Electrical and Electronics Engineers Inc., 2009) Hanmandlu, M.; Verma, O.P.; Kumar, N.K.; Kulkarni, M.
A new approach is presented for the enhancement of color images using the fuzzy logic technique. An objective measure called exposure has been defined to provide an estimate of the underexposed and overexposed regions in the image. This measure serves as the dividing line between the underexposed and overexposed regions of the image. The hue, saturation, and intensity (HSV) color space is employed for the process of enhancement, where the hue component is preserved to keep the original color composition intact. A parametric sigmoid function is used for the enhancement of the luminance component of the underexposed image. A power-law operator is used to improve the overexposed region of the image, and the saturation component of HSV is changed through another power-law operator to recover the lost information in the overexposed region. Objective measures like fuzzy contrast and contrast and visual factors are defined to make the operators adaptive to the image characteristics. Entropy and the visual factors are involved in the objective function, which is optimized using the bacterial foraging algorithm to learn the parameters. Gaussian and triangular membership functions (MFs) are chosen for the underexposed and overexposed regions of the image, respectively. Separate MFs and operators for the two regions make the approach universal to all types of contrast degradations. This approach is applicable to a degraded image of mixed type. On comparison, this approach is found to be better than the genetic algorithm (GA)-based and entropy-based approaches. © 2009 IEEE.
A simple single seeded region growing algorithm for color image segmentation using adaptive thresholding
(2011) Verma, O.P.; Hanmandlu, M.; Susan, S.; Kulkarni, M.; Jain, P.K.
In this paper, we present a region growing technique for color image segmentation. Conventional image segmentation techniques using region growing requires initial seeds selection, which increases computational cost & execution time. To overcome this problem, a single seeded region growing technique for image segmentation is proposed, which starts from the center pixel of the image as the initial seed. It grows region according to the grow formula and selects the next seed from connected pixel of the region. We use intensity based similarity index for the grow formula and Otsu's Adaptive thresholding is used to calculate the stopping criteria for the grow formula. We apply the proposed method to the Berkley segmentation database images and discuss results based on Liu's F-factor that shows efficient segmentation. Â© 2011 IEEE.
Adaptive OFDM vs single carrier modulation with frequency domain equalization
(2009) Kaur, I.; Thakur, K.; Kulkarni, M.; Gupta, D.; Arora, P.
The aim of the present paper is to compare multicarrier and single carrier modulation schemes for wireless communication systems. In both cases the fast Fourier transform (FFT) and its inverse are utilized. In case of OFDM (orthogonal frequency division multiplexing), the inverse FFT transforms the complex amplitudes of the individual subcarriers at the transmitter into time domain. At the receiver the inverse operation is carried out. In case of single carrier modulation, the FFT and its inverse are used at the input and output of the frequency domain equalizer in the receiver. Different single carrier and multi-carrier transmission systems are simulated with time-variant transfer functions measured with a wideband channel sounder. In case of OFDM, the individual sub-carriers are modulated with fixed and adaptive signal alphabets. Furthermore, a frequency-independent as well as the optimum power distribution are used. Single carrier modulation uses a single carrier, instead of the hundreds or thousands typically used in OFDM, so the peak-to-average transmitted power ratio for single carrier modulated signals is smaller. This in turn means that a SC system requires a smaller linear range to support a given average power. This enables the use of cheaper power amplifier as compared to OFDM system. � 2009 IEEE.
An Autonomous Frequency Reconfigurable Antenna Using Slotline Open-Loop Resonators
(Institute of Electrical and Electronics Engineers Inc., 2021) Polaiah, G.; Kandasamy, K.; Kulkarni, M.
This paper presents a slotline open-loop resonators based frequency reconfigurable antenna with autonomous switching of frequency bands. The dual-port slot antenna is designed to operate at 2.1 GHz when excited at port-1, and when port-2 is excited, the antenna can be reconfigured to operate at 2.85 GHz and 5.52 GHz, respectively. Port-1 is used to receive the control signal, which is converted to a DC signal using a rectifier. The rectified control signal is used to switch the operating frequency bands of the port-2. The proposed antenna configuration gives the flexibility of remote/wireless control of the operating frequency. The antenna prototype is fabricated and measured for observing the frequency switching at port-2. The measured results show that the antenna has been effectively switched from lower band frequency (2.8 GHz) to upper band frequency (5.41 GHz) when the PIN diode is ON. The proposed antenna in its final configuration can be potentially suitable for transmitter reconfigurable antenna without the need for external DC bias voltage. © 2021 Institute of Electrical and Electronics Engineers Inc.. All rights reserved.
An electronically switchable UWB to narrow band antenna for cognitive radio applications
(John Wiley and Sons Inc. P.O.Box 18667 Newark NJ 07191-8667, 2020) Jacob, N.; Kulkarni, M.; Kandasamy, K.
Cognitive radio (CR) is designed to achieve intelligent spectrum sensing and sharing, in order to solve spectrum underutilization problem. Conventional CR uses multiple/multiport antenna to switch between UWB and narrow band (NB) frequencies for primary and secondary users. In this article, we propose a compact frequency reconfigurable single port antenna using PIN diodes, to switch between UWB and NB frequencies. A circular disc monopole antenna with partial ground plane is designed to deliver UWB response. Three interdigital capacitors (IDC) are electrically connected to a partial ground plane and feed line using PIN diodes. OFF condition of all PIN diodes will provide the UWB response of 2.8 to 10.6 GHz and ON condition of the diodes will result in 36 different NB frequencies, completely covering the UWB spectrum. A simulation study carried out by incorporating a varactor diode into IDC, clearly shows that, the antenna resonance can be switched using PIN diodes and each resonant frequency can be fine-tuned independently, with in the band of interest. This is the unique feature of proposed antenna, which facilitates the technology for CR based internet of things applications in 5G wireless communication networks. © 2020 Wiley Periodicals, Inc.
An improved turbo decoding scheme for impulsive channel
(2010) Savitha, H.M.; Kulkarni, M.
This paper proposes a novel turbo decoding scheme for additive white class A noise (AWAN) channel. It compares the performance of turbo coded systems with Quadrature Phase Shift Keying (QPSK) and 16-Quadrature Amplitude Modulation (16-QAM) on AWAN channel with two different channel values-one computed as per additive white Gaussian noise (AWGN) channel conditions and the other as per AWAN channel conditions. The results show that the use of appropriate channel value in turbo decoding helps to combat the impulsive noise more effectively. Also, the Bit error rate (BER) performance of the proposed model for AWAN channel is compared with that of AWGN channel. It is observed that they exhibit comparable BER performance. Â©2010 IEEE.
Analysis of symbol error probability in GFDM under generalized ????? channels: An approach based on probability density function for beyond 5G wireless applications
(Elsevier GmbH, 2025) Bodempudi, N.S.P.; Chaturvedi, A.; Rashmi, R.; Kulkarni, M.
Generalized Frequency Division Multiplexing (GFDM) is a flexible multicarrier modulation scheme tailored to meet the diverse requirements of 5G and beyond (B5G) wireless systems. It provides flexibility to select subsymbols, subcarriers, and pulse-shaping filters, making it suitable for various B5G communication needs. Moreover, GFDM includes orthogonal frequency division multiplexing (OFDM) and single carrier frequency domain equalization (SC-FDE) as special cases. Since fading conditions greatly affect communication reliability, this paper derives a closed-form expression for the symbol error probability/symbol error rate (SEP/SER) of GFDM using M-QAM and M-PSK in generalized ????? fading channels. The study examines how fading parameters (?,?,?), pulse-shaping filters, roll-off factor, and subsymbol count influence SER performance. Results show these factors have a significant impact on error probability. This comprehensive analysis provides important insights for evaluating GFDM performance under complex fading scenarios, making it a valuable reference for GFDM system design for B5G wireless applications. © 2025
BER performance and energy efficiency of Luby Transform codes with varying BPSK thresholds over the Free Space Optical channel
(2013) Prakash, G.; Kulkarni, M.; Shripathi, Acharya U.
In this paper we analyse the Bit Error Rate(BER) performance and energy efficiency of Luby Transform (LT) codes when the signals are Binary Phase shift Keying (BPSK )modulated with varying thresholds and transmitted over the Free Space Optical (FSO)Channel in a wireless sensor network. We model the FSO channel using the Gamma-Gamma distribution function and compare the performance for varied turbulence parameters. We also show how the distribution of the BPSK symbols varies as the distribution varies when the turbulence changes from strong to weak. Use of forward error correction helps in the recovery of the original signal even if some transmitted signals are corrupted during transmission. We analyse the FSO system, which employs Luby Transform Codes, which do not have a fixed code rate. They are considered Rateless, and as many codewords are generated as required to recover all the message bits. We show an increase in SNR and reduced energy per bit for the same BER with LT codes as the BPSK threshold increases. � 2013 IEEE.
BER performance and energy efficiency of Luby Transform codes with varying BPSK thresholds over the Free Space Optical channel
(2013) Prakash, G.; Kulkarni, M.; Sripati, U.
In this paper we analyse the Bit Error Rate(BER) performance and energy efficiency of Luby Transform (LT) codes when the signals are Binary Phase shift Keying (BPSK )modulated with varying thresholds and transmitted over the Free Space Optical (FSO)Channel in a wireless sensor network. We model the FSO channel using the Gamma-Gamma distribution function and compare the performance for varied turbulence parameters. We also show how the distribution of the BPSK symbols varies as the distribution varies when the turbulence changes from strong to weak. Use of forward error correction helps in the recovery of the original signal even if some transmitted signals are corrupted during transmission. We analyse the FSO system, which employs Luby Transform Codes, which do not have a fixed code rate. They are considered Rateless, and as many codewords are generated as required to recover all the message bits. We show an increase in SNR and reduced energy per bit for the same BER with LT codes as the BPSK threshold increases. Â© 2013 IEEE.
BER performance enhancement for secure wireless communication systems based on chaotic-MIMO techniques
(2013) Abdulameer, L.F.; Jignesh, D., J.; Shripathi, Acharya U.; Kulkarni, M.
The growing interest in the use of chaotic techniques for enabling secure communication in recent years has been motivated by the emergence of a number of wireless services which require the service provider to provide low bit error rates (BER) along with information security. This paper investigates the feasibility of using chaotic communications over Multiple-Input-Multiple-Output (MIMO) channels. While the use of Chaotic maps can enhance security, it is seen that the overall BER performance gets degraded when compared to conventional communication schemes. In order to overcome this limitation, we have proposed the use of a combination of Chaotic modulation and Alamouti Space Time Block Code. The performance of Chaos Shift Keying (CSK) with 2�1 and 2�2 Alamouti schemes for different chaotic maps over wireless channels has been studied. It has been shown that the use of these schemes can provide security enhancement without the penalty of degradation of BER performance. Copyright � 2013 SPIE.
BER performance enhancement for secure wireless communication systems based on chaotic-MIMO techniques
(2013) Abdulameer, L.F.; Jignesh, J.D.; Sripati, U.; Kulkarni, M.
The growing interest in the use of chaotic techniques for enabling secure communication in recent years has been motivated by the emergence of a number of wireless services which require the service provider to provide low bit error rates (BER) along with information security. This paper investigates the feasibility of using chaotic communications over Multiple-Input-Multiple-Output (MIMO) channels. While the use of Chaotic maps can enhance security, it is seen that the overall BER performance gets degraded when compared to conventional communication schemes. In order to overcome this limitation, we have proposed the use of a combination of Chaotic modulation and Alamouti Space Time Block Code. The performance of Chaos Shift Keying (CSK) with 2Ã—1 and 2Ã—2 Alamouti schemes for different chaotic maps over wireless channels has been studied. It has been shown that the use of these schemes can provide security enhancement without the penalty of degradation of BER performance. Copyright Â© 2013 SPIE.
BER performance enhancement for secure wireless communication systems based on DCSK-MIMO techniques under Rayleigh fading channel
(2013) Abdulameer, L.F.; Jokhakar, J.D.; Sripati, U.; Kulkarni, M.
There has been a growing interest in the use of chaotic techniques for enabling secure communication in recent years. This need has been motivated by the emergence of a number of wireless services which require the channel to provide very low bit error rates (BER) along with information security. As more and more information is transacted over wireless media, there has been increasing criminal activity directed against such systems. This paper investigates the feasibility of using chaotic communications over Multiple-Input-Multiple-Output (MIMO) channels. We have studied the performance of differential chaos shift keying (DCSK) with 2×2 Alamouti scheme and 2×1 Alamouti scheme for different chaotic maps over additive white Gaussian noise (AWGN) and channels disturbed by Rayleigh fading. Both the inherently wideband DCSK modulation and the space-time block code (STBC) are techniques that can mitigate the effect of multipath fading. The use of these schemes allows us to enhance security without degrading the BER performance for Rayleigh fading channels. We have employed an exact method to analyze the performances of DCSK communication system over fading channel. Our simulations indicate that the combination of the STC and tent map provides the best BER performance in addition to security when compared to the choice of other maps. Hence, this study shows that the use of these schemes can allow the user to enhance security without degrading the BER performance while communicating over these channels. © 2013 Allerton Press, Inc.
BER performance enhancement for secure wireless optical communication systems based on chaotic MIMO techniques
(2014) Abdulameer, L.F.; Jignesh, J.D.; Sripati, U.; Kulkarni, M.
There has been a growing interest in the use of chaotic techniques for enabling secure communication in recent years. This need has been motivated by the emergence of a number of wireless services which require the channel to provide low bit error rates (BER) along with information security. The aim of such activity is to steal or distort the information being conveyed. Optical Wireless Systems (basically Free Space Optic Systems, FSO) are no exception to this trend. Thus, there is an urgent necessity to design techniques that can secure privileged information against unauthorized eavesdroppers while simultaneously protecting information against channel-induced perturbations and errors. Conventional cryptographic techniques are not designed for protecting information integrity when data is being transferred over a harsh communication medium. Hence, a separate channel coding protocol is often necessary to achieve this goal. Our work indicates that the use of a suitable Chaotic Shift Keying (CSK) map combined with an appropriate Space-Time Code (STC) can allow both requirements to be met. In this paper, we have concentrated on investigating the error rate performance of chaotic-wireless optical communication links operating over atmospheric channel, where the turbulence-induced fading is described by the Gamma-Gamma and log-normal distributions. The main aim of the paper is to assess the feasibility of employing Space-Time Coded chaotic communications over Multiple Input Multiple Output (MIMO) communication channels. Our simulations indicate that the combination of the STC and tent map provides the best BER performance in addition to security when compared to the choice of other maps. © 2013 Springer Science+Business Media Dordrecht.
BER performance improvement for secure wireless communication systems based on CSK-STBC techniques
(2012) Abdulameer, L.F.; Jignesh, D.J.; Shripathi, Acharya U.; Kulkarni, M.
There has been a growing interest in the use of chaotic techniques for enabling secure communication in recent years. This need has been motivated by the emergence of a number of wireless services which require the channel to provide very low bit error rates (BER) along with information security. This paper investigates the feasibility of using chaotic communications over Multiple-Input Multiple-Output (MIMO) channels by combining chaos modulation with a suitable Space Time Block Code (STBC). It is well known that the use of Chaotic Modulation techniques can enhance communication security. However, the performance of systems using Chaos modulation has been observed to be inferior in BER performance as compared to conventional communication schemes. In order to overcome this limitation, we have proposed the use of a combination of Chaotic modulation and Alamouti Space Time Block Code. We have studied the performance of Chaos Shift Keying (CSK) with 2�1 Alamouti scheme for different chaotic maps over Additive White Gaussian Noise (AWGN) and Rayleigh fading channels. Our simulations indicate that the use of the Alamouti schemes can allow service providers to enhance security without degrading the BER performance while communicating over these channels. � 2012 IEEE.
BER performance improvement for secure wireless communication systems based on CSK-STBC techniques
(2012) Abdulameer, L.F.; Jokhakar Jignesh, D.J.; Sripati, U.; Kulkarni, M.
There has been a growing interest in the use of chaotic techniques for enabling secure communication in recent years. This need has been motivated by the emergence of a number of wireless services which require the channel to provide very low bit error rates (BER) along with information security. This paper investigates the feasibility of using chaotic communications over Multiple-Input Multiple-Output (MIMO) channels by combining chaos modulation with a suitable Space Time Block Code (STBC). It is well known that the use of Chaotic Modulation techniques can enhance communication security. However, the performance of systems using Chaos modulation has been observed to be inferior in BER performance as compared to conventional communication schemes. In order to overcome this limitation, we have proposed the use of a combination of Chaotic modulation and Alamouti Space Time Block Code. We have studied the performance of Chaos Shift Keying (CSK) with 2Ã—1 Alamouti scheme for different chaotic maps over Additive White Gaussian Noise (AWGN) and Rayleigh fading channels. Our simulations indicate that the use of the Alamouti schemes can allow service providers to enhance security without degrading the BER performance while communicating over these channels. Â© 2012 IEEE.
BER Performance Improvement of Dual Chaotic Maps Based on STBC Communication System
(University of Baghdad, 2022) Abdulameer, L.F.; Sripati, U.; Kulkarni, M.
Sensitive information of any multimedia must be encrypted before transmission. The dual chaotic algorithm is a good option to encrypt sensitive information by using different parameters and different initial conditions for two chaotic maps. A dual chaotic framework creates a complex chaotic trajectory to prevent the illegal use of information from eavesdroppers. Limited precisions of a single chaotic map cause a degradation in the dynamical behavior of the communication system. To overcome this degradation issue in, a novel form of dual chaos map algorithm is analyzed. To maintain the stability of the dynamical system, the Lyapunov Exponent (LE) is determined for the single and dual maps. In this paper, the LE of the single and dual maps have been computed numerically. Increasing the dynamical behavior of the system by using more complex chaotic maps leads to inferiority in the overall system performance. So, in this work, the BER performance for the dual and single chaotic maps by exploiting the benefits of a hybrid Chaos Shift Keying-Multiple-Input-Multiple-Output (CSK-MIMO) communication system has been investigated. The results show that the dual tent map has more randomness, whereas the single logistic map has the least randomness. As well as the CSK-MIMO gives an outstanding BER performance when it compared with the SISO system which helps in reducing the system’s inferiority. © 2022, University of Baghdad. All rights reserved.