Browsing by Author "Sripati, U."

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A cost-effective system for wireless power transmission
(2010) Malani, P.; Arjun, Y.; Sripati, U.
In recent years, the notion of transfer of power using wireless techniques has attracted many researchers. Transfer of power by wireless means has been recently demonstrated in the Massachusetts Institute of Technology (MIT). This system operates at 9.9 MHz. In this paper, we have discussed the design of a simple and cost-effective system which can enable transmission of power over short distances. We have employed the H - Bridge Inverter configuration to convert DC power to high frequency (100 kHz) which is then radiated with the help of a suitable loop antenna. It is observed that this system can also be used as a induction heating unit. In this form it can be used to replace conventional convection heating based electric stoves. Â©2010 IEEE.
A low SNR approach to substation communication using powerline for EMI reduction
(2012) Itagi, R.L.; Vittal, K.P.; Sripati, U.
Use of space time code concatenated with BCH (Bose Choudhari Hocquenghem) code is analyzed for performance in powerline channel with impulse noise. Performance of BCH-Space time code is worked in this paper for application of narrowband power line communication. BCH code (63, 36) with t=5 is designed and implemented in TMS320C6713 Digital Signal Processor, which is interfaced with Matlab version 7.4, where power line channel and impulse noise are simulated. These results are compared with Turbo coded OFDM scheme for powerline channel. From the results, reduction in carrier power requirement is found for BCH Space time code. Space time code has now become popular in wireless communication, as application in multipath channel. Since power line can provide different uncorrelated paths to realize multipaths effect, it is possible to apply space time code for powerline channel. In this paper, powerline is modelled as a multipath channel and impulse noise as Middleton class-A noise, on Matlab 7.4 platform. The BCH code of n=63, k=36, t=5, is designed and tested in a Digital Signal Processor (DSP) TMS320C6713. Interfacing is done using JTAG from processor to Matlab where power line, impulse noise and space time code are simulated. The performance of the system as communication system for narrowband PLC is tested for different channel and noise conditions. The results are used to find SNR requirement at a Pe (Probability of error) of the order of 10 -5 and for carrier signal strength to be within EMI (Electro Magnetic Interference) and EMC(Electro Magnetic compatibility) limits. Use of a BCH code with more better error correcting capacity, will further reduce the SNR requirement, hence will reduce carrier power. Â© 2012 IEEE.
Adaptive receive-antenna selection technique for Spatial Modulation MIMO systems
(Institute of Electrical and Electronics Engineers Inc., 2015) Neha, N.; Koila, S.; Prashantha Kumar, H.; Sripati, U.
In this paper, we propose an adaptive receive antenna selection technique for Spatial Modulation (SM) MIMO systems. The proposed method is simple and uses channel state information (CSI) available at the receiver to choose the best subset of active receive antennas among the available Nr receive antennas. Simulation results show that SM MIMO system with the proposed receive antenna selection scheme provides a performance gain of approximately 5 dB over conventional SM system (SM MIMO system without antenna selection). The proposed scheme does not increase the RF chain requirement at the receiver and retains all the benefits of SM MIMO. Â© 2015 IEEE.
Application of Error Correction Codes for Enhancing Data Integrity in Power Line Channel
(National Institute of Technology Karnataka, Surathkal, 2013) Itagi, Rajeshwari L; K. P., Vittal; Sripati, U.
The use of existing power lines for home/industry/substation automation has drawn the attention of many researchers in the recent years because this infrastructure is easily available everywhere. However, the Power Line channel has been primarily designed for power transfer at low frequencies. Hence, the propagation characteristics of this channel are not well suited to support high speed data transmission and ensuring reliable high speed and error free data transmission on this channel is a very challenging task. Many researchers have been attracted to this challenging field in recent years and a variety of techniques from the domain of Digital Signal Processing and Communication Engineering have been applied to solve some of the challenges posed by this application. The three critical channel parameters namely noise, impedance and attenuation are found to be highly unpredictable and variable with time, frequency and location. Further, the regulatory standards designed to prevent spurious radiation restrict the carrier power that can be used for digital modulation. In this work, we have concentrated on the use of Medium Voltage (MV) Power Line (< 30 kV) for narrow band applications. After a study of relevant literature and an understanding of mathematical models used to describe the variation of channel parameters, a suitable model has been simulated in MATLAB® platform. Simulation results presented by the channel model have been obtained for different channel conditions such as line length, noise variations and variations in transfer function (attenuation) of the channel and for different data size. The frequency band employed in narrowband power line communication is restricted to a value less than 500 kHz. An effort is made in the thesis to devise a powerful error correcting code which can eliminate the errors caused by channel impairments. Power line channel is modeled using multipath model. As noise experienced on power line channels is a mixture of Gaussian and Impulsive varieties, it is modeled by using the Middleton Class-A pdf. Taking into account the channel behavior; two channel coding strategies were deployed. In the first approach a four state Turbo code was combined with a 32-carrier OFDM modulator and the performance of this combination was studied under various channel conditions. In the second approach, a Bose-Choudhari-Hocquenghem (BCH)code was concatenated with the Alamouti Space-Time Block code and the performance of the channel was similarly evaluated. To realize the Turbo coded OFDM scheme, a four state Turbo code using Recursive Systematic Convolutional (RSC) encoder/decoder pair was designed. The output of the encoder was modulated by 32 sub carrier OFDM (designed using IFFT and FFT). The efficacy of this arrangement in ensuring data integrity over the MV power line channel was tested. To realize the second approach, a BCH code with parameters was designed and encoding/decoding processes were implemented. BCH code in concatenation with Alamouti 2x1 space time code (with PSK modulation) was tested. A partial hardware implementation was realized by employing a Digital Signal Processor TMS 320C6713 for encoding/decoding and MATLAB® for simulating the power line channel. Data input present in text form encoded and decoded after transmission through the channel. This process allows the visualization of the power of error correction algorithms. Performance evaluation of the two proposed schemes for channel code and modulation design namely Turbo coded OFDM and BCH coded space time code were carried out. The performance criteria for the evaluation include the bit error rate (BER) at a specific signal to noise ratio (SNR). The reflections at branching points (load locations) vary the attenuation profile of the link. As a result, the effect of different parameters on the channel attenuation was observed based on the number of loads and length of the link. A BER analysis was performed to compare the performance of the channel under impulsive noise conditions under three impulsive scenarios. The first scenario was specified as . The second scenario was specified as and the the third scenario was specified as . A comparison of the relative performance of uncoded and coded schemes reveals the following: Scheme 1 achieves BER of 10-5 at SNR=55 dB for (case 1 impulse noise), with channel attenuation varying between 10 dB to 50 dB. Scheme 2 achieves BER of 10-5 at SNR=50dB for (case 1 impulse noise), with channel attenuation on two paths varying between 18 dB and 6 dB.Both schemes have achieved a BER of 10-5 at SNR=66 dB for case 2 impulse noise), with 10dB to 50 dB channel attenuation for scheme 1 and with 16 dB and 34 dB channel attenuation on two paths for scheme 2. Following remark can be made with reference to the discussion on results: Both schemes 1 and 2 have given equivalent performance under similar channel conditions (attenuation and noise), when the error correcting capacity of channel code used in scheme 2 is . After a thorough study and implementation of both approaches, it was observed that both schemes exhibit equivalent performance under similar channel conditions (attenuation and noise levels). With enhanced error correction capacity with t=11, a BCH coded space time code will require lesser SNR to give the same performance as OFDM under similar channel conditions.
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, 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.; 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.
Bit error rate analysis of coded OFDM for digital audio broadcasting system, employing parallel concatenated convolutional turbo codes
(Institute of Electrical and Electronics Engineers Inc., 2015) Jacob, N.; Sripati, U.
In this paper we present a study of Bit Error Rate (BER), for Digital Audio Broadcasting (DAB) system, employing Coded OFDM with different channel coding schemes. Analysis is carried out for convolutional coded and turbo coded data in an Additive White Gaussian Channel (AWGN) based on different constraint lengths and code generator polynomials used for coding. A comparative study on the computational complexity is also done by applying an audio signal and measuring the data processing time per frame, on computers with different processor speeds. It is shown that a coding gain of approximately 6 dB is achieved using turbo coding when compared to convolutional coding, at a cost of higher computational complexity. Â© 2015 IEEE.
Design and Construction of Algebraic Codes for Enhancing Information Integrity in Data Storage Systems
(National Institute of Technology Karnataka, Surathkal, 2013) K, Rajesh Shetty; Sripati, U.
Data storage devices have become ubiquitous in present day information driven society. It is essential that storage devices exhibit very high levels of data integrity. Therefore, data integrity is a fundamental aspect of storage, security and reliability. NAND and NOR Flash memories [Chen, Y. 2008], [Mielke, N et al. 2008], [Gal, E. et al. 2005], [Jiang, A et al. 2010] are widely used for data storage because of their compactness and low power consumption. Data stored in non-volatile memory is usually critical to proper system operation, and corruption of data can lead to system failure. Hence data corruption is a major concern in applications that rely on nonvolatile memory for long-term data storage. Many techniques have been employed to improve the reliability of these devices. These techniques can be divided into two categories. In the first approach, improvements are carried out in the fabrication process to reduce the Raw Bit Error Rate (RBER). The second option is to use Error Correction Techniques to improve the RBER level to levels that are deemed acceptable to most users [Sun, F. et al. 2007], [Sun,F et al. 2006], [Chen, Y. and Parhi, K. 2004], [Mielke, N. et al. 2008]. Error Control Code (ECC) techniques (i.e., techniques capable of detecting and correcting errors in processed and stored data by using redundant bits in addition to information bits according to a given coding strategy) [Pless, V. and Huffman, W.C. 1998] have been commonly used at board level for many years to enhance the reliability of memory systems [Bertozzi, D. et al. 2005]. However, as memory chips become denser, they also become more prone to errors, as a consequence of both the reduced cell size and the increased cell count within a single die. Moreover, read and write operations are made more critical by both technology scaling down and higher speed requirements. On the other hand, higher and higher reliability is required for storage systems in a large variety of applications. Generally high storage density is achieved by reducing the size of the elementary memory cell. However, for non-volatile memories, some physical phenomena makesv an aggressive reduction of the memory cell size difficult [Atwood, G. et al. 1997], [Wang, Z. and Karpovsky, M. 2011]. An alternative solution to reduce the cost per bit and increase the storage density is to adopt the multilevel approach. It consists of placing a multiplicity of charge amount in the floating gate, thus allowing the cell to store more than one bit. However, the multilevel storage requires the consideration of three basic issues: (i) accuracy of write operation (necessary to place the correct amount of charge of the floating gate). (ii) precision of the charge sensing (required to discriminate the different threshold voltages). (iii) stability of charge over an extended time period. Although Multi Level Cell (MLC) memory has higher density than Single Level Cell (SLC) memory, MLC is more vulnerable to errors because small fluctuation of the charge amount in the floating gate and slight variation of gate voltage result in misreading of stored data [Sun, F. et al. 2007], [Sun,F et al. 2006], [Maeda, Y et al. 2009], [Lin, H et al. 2002], [Ankolekar, P. P et al.2010]. ECC is a cost effective method to enhance the integrity of data storage systems. Very stringent values of application BER, which would ordinarily require complex and expensive fabrication techniques as well as expensive materials, can be met very easily by employing ECC. Storage devices characterized by high RBER values can be made to yield application BERs as small as desired by the use of suitable ECC techniques. The fraction of erroneous bits that remain uncorrected after applying ECC constitute the uncorrectable bit error rate (UBER). UBER is a useful reliability metric for data storage devices and is used to specify the data corruption rate in the information given to the user after correction by ECC algorithms. ECC algorithms can also correct errors that may manifest at any later stage during the life of the device. Hence use of ECC techniques has been widely accepted by the semiconductor manufacturing industry to enhance the RBER to levels demanded by applications. In this thesis, we have made an attempt to synthesize a number of codes for use in data storage systems with error correcting capability exceeding the state of art asvi specified in the industry documentation. In the initial part of the thesis, the focus is on the synthesis of codes for enhancing data integrity in flash memories composed of SLCs. While studying the flash memory organization, two memory models, namely Memory model 1 and Memory model 2 are identified and the codes are synthesized separately for these memory models. As compared to the current standard, [Mehnert, A. 2008] where six bits in errors can be corrected over a span of 4096 information bits (one sector), we propose codes that can correct up to nine bits in error per sector. The various generator polynomials are computed. As the performance of the error control code improves with increase in length, we were motivated to consider the combination of two sectors to constitute the information block. For this scenario, we propose codes that can correct up to eighteen bits in error over a span of 8192 bits (two sectors). Further, using Memory model 2, we have synthesized and proposed codes that can correct up to eighteen bits in errors per sector. The performance of these codes is quantified by computing values of the probability of decoding error. To summarize, the main objective of this work has been to design, construct and synthesize a large group of codes which can be used to enhance the data integrity levels associated with flash memory devices so as to make them useful in a wider class of applications. With a view to make these synthesized codes, readily acceptable to industry, we have strictly adhered to the memory architecture specified in the literature.
Design and construction of BCH codes for enhancing data integrity in multi level flash memories
(Inderscience Publishers, 2012) Rajesh Shetty, K.; Ramakrishna, K.; Prashantha Kumar, H.; Sripati, U.
Flash memories have found extensive application for use in storage devices. The storage capacity and reliability of these devices have increased enormously over the years. With increase in density of data storage, the raw bit error rate (RBER), associated with the storage device increases. Error control coding (ECC) can be used to reduce the RBER to acceptable values so that these devices can be employed to store information in applications where data corruption is unacceptable. In this paper, we describe the synthesis of BCH codes for flash memories based on multi level cell (MLC) concept. This is in continuation of our work on synthesis of BCH codes for improving the performance of flash memories based on single level cells (SLC). The improvement in device integrity resulting from the use of these codes has been quantified in this paper along with computation of parameters which allows modelling of flash memory as an equivalent channel. While synthesising codes, we have adhered to the limitations imposed by the memory architecture. Use of these codes in storage devices will result in considerable enhancement of device reliability and consequently open up many new applications for this class of storage devices. © 2012 Inderscience Enterprises Ltd.
Enhancement of security for free space optics based on reconfigurable chaotic technique
(2013) Abdulameer, L.F.; Jignesh, J.D.; Sripati, U.; Kulkarni, M.
Free Space Optical (FSO) technology offers highly directional, high bandwidth communication channels. This technology can provide fiber-like data rate over short distances. In order to improve security associated with data transmission in FSO networks, a secure communication method based on chaotic technique is presented. In this paper, we have turned our focus on a specific class of piece wise linear one-dimensional chaotic maps. Simulation results indicate that this approach has the advantage of possessing excellent correlation property. In this paper we examine the security vulnerabilities of single FSO links and propose a solution to this problem by implementing the chaotic signal generator "reconfigurable tent map". As synchronization between transmitter and receiver is essential for the correct operation of such schemes, we have also attempted to determine parameters such as auto-and cross-correlation that determine the ease with which synchronization between transmitter and receiver can be achieved. It is demonstrated that cross correlation is very close to zero and auto-correlation is Î´-like. The overall system is implemented in the MATLAB Simulink Digital Signal Processing (DSP) Builder. Copyright Â© 2013 SPIE.
Enhancing the error-correcting capability of imai-kamiyanagi codes for data storage systems by adopting iterative decoding using a parity check tree
(2012) Kumar, H.; Sripati, U.; Rajesh Shetty, K.; Shankarananda, B.
A novel low-complexity, soft decision technique which allows the decoding of distance-5 double error-correcting Imai-Kamiyanagi codes by using a parity check tree associated with the Tanner graph is proposed. These codes have been applied to memory subsystems and digital storage devices in order to achieve efficient and reliable data processing and storage. For the AWGN channel, gains in excess of 1.5 dB at reasonable bit error rates with respect to conventional hard decision decoding are demonstrated for the (46, 32), (81, 64), and (148, 128) shortened Imai-Kamiyanagi codes. Copyright © 2012 by the IETE.
FPGA implementation of a BCH Codec for free space optical communication system
(Institute of Electrical and Electronics Engineers Inc., 2014) Koila, S.; G.D., G.D.; Kulkarni, M.; Sripati, U.
Future Free Space Optical (FSO) communication systems have the potential of communicating data at very high rates with very high levels of integrity over distances of up to a few kilometers (for terrestrial links). This technology has also been a candidate for setting up very high speed (âˆ¼3 Gbps) and highly reliable (BER âˆ¼10-9) communication links between satellites in geo-synchronous orbits and ground stations. Since the free space optical medium can induce many forms of distortion (atmospheric turbulence effects, optical beam wander etc), the use of a channel code to detect and correct errors during the process of information transfer over the channel is essential. A correctly designed channel code can reduce the raw BER from unacceptable values to values that can be tolerated in many applications. In this paper, we have designed a Codec (encoder/decoder) pair for a (31, 16, 3) Bose, Ray-Chaudhuri, and Hocquenghem (BCH) code on the Nexys-4 FPGA platform. The performance of this BCH Codec has been tested over an indoor FSO channel and the improvement in terms of BER has been quantified. An improved syndrome computation circuit, parallel Chien search implementation and an improved method for calculating inverses in a finite field are the new features incorporated in this paper. We have been able to design and implement circuits which use these optimized approach and deliver real time encoding and decoding with an information transfer rate of 2 Mbps and can be extended upto a speed of 418Mbps. Â© 2014 IEEE.
High-speed and parallel approach for decoding of binary BCH codes with application to Flash memory devices
(2012) Kumar, H.; Sripati, U.; Rajesh Shetty, K.
In this article, we propose a high-speed decoding algorithm for binary BCH codes that can correct up to 7bits in error. Evaluation of the error-locator polynomial is the most complicated and time-consuming step in the decoding of a BCH code. We have derived equations for specifying the coefficients of the error-locator polynomial, which can form the basis for the development of a parallel architecture for the decoder. This approach has the advantage that all the coefficients of the error locator polynomial are computed in parallel (in one step). The roots of error-locator polynomial can be obtained by Chien's search and inverting these roots gives the error locations. This algorithm can be employed in any application where high-speed decoding of data encoded by a binary BCH code is required. One important application is in Flash memories where data integrity is preserved using a long, high-rate binary BCH code. We have synthesized generator polynomials for binary BCH codes (error-correcting capability, s) that can be employed in Flash memory devices to improve the integrity of information storage. The proposed decoding algorithm can be used as an efficient, high-speed decoder in this important application. © 2012 Taylor & Francis.
Hybrid LDPC-STBC communications system based on chaos
(Association for Computing Machinery, 2019) Abdulameer, L.F.; Jignesh, J.D.; Sripati, U.; Kulkarni, M.
This paper attempts to show a communication strategy of implementing a hybrid of Low-Density Parity Check (LDPC) and Multiple Input Multiple Output (MIMO) based on chaotic technique. Many chaotic techniques which consider a significant part in the information security schemes was proposed, but one of the greatest defy in chaotic communications is the limitation of the system performance due to realistic channel conditions. We have investigated the theory and carried out detailed analysis pertaining to encoding/decoding of chaotic modulation schemes, the use of suitable LDPC coded MIMO schemes for providing secure and reliable communication. The aim of the hybrid scheme is that a correctly designed coded Space Time Block Code (STBC) is used to mitigate the declination of the signal caused by multipath scattering. The Bit-Error Rate (BER) performance of this hybrid scheme with two transmit antennas and two receive antennas under Rayleigh fading model is evaluated. The results indicate that that implementing LDPC (regular and irregular) coded STBC system decrease BER as compared with systems without implementing LDPC code for chaotic communication systems. Mathematical analysis for the hybrid system has been derived and achieved using Matlab. Â© 2019 Association for Computing Machinery.
Modified signal design for multistream spatial modulation over spatially correlated channels
(Institute of Electrical and Electronics Engineers Inc., 2017) G.D., G.S.; Koila, K.; Raghavendra, R.; Sripati, U.
In this paper, we describe a modified signal design for Multistream Spatial Modulation (MSM). The fundamental idea behind MSM is to activate multiple antennas and transmit complex symbols along with active antenna indices. Here, a modified MSM technique explicitly designed to combat the effect of spatial correlation in realistic channel scenarios is proposed. In this MSM scheme, two antennas are made active all the time, mapping for antenna selection is judiciously adopted from primary and secondary constellation points. Secondary constellations are obtained through single geometric interpolation of the primary constellation points. Simulation studies show that for a fixed number of antenna combinations and spectral efficiency, the proposed scheme produces a performance improvement of at least 4 dB at a ABER of 10-5 over all traditional Spatial Modulation (SM) systems, more specifically Enhanced Spatial Modulation (ESM), Quadrature Spatial Modulation (QSM) and Double Spatial Modulation (DSM) systems when employed over dense spatially correlated channels. Furthermore, an upper bound on the average bit error probability (ABEP) for the modified MSM scheme has been derived and quantified. Monte Carlo simulation results corroborate the close correspondence between analytical and the obtained simulation results. Â© 2017 IEEE.
Performance analysis of energy efficient asymmetric coding and modulation schemes for wireless sensor networks
(2010) Kamath, G.M.; Shekar, Y.; Abhijith, K.G.; Sripati, U.; Kulkarni, M.
Wireless Sensor Networks generally operate under severe energy constraints. In many cases, the networks are star connected with battery-powered nodes sensing data and sending it to a centrally-powered base station, whose energy constraints are more fore-bearing than that of the nodes. In this paper, an approach for energy efficient communication by using different channel codes on the base-station to node link (downlink) and node to base-station link (uplink) is proposed and analysed for such a network topology. This is in effect shifting complexity from the node to the base station while continuing to have the same BER performance. Also the use of more energy efficient modulation schemes are explored. Â©2010 IEEE.