Browsing by Author "Prakash, G."

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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.
Classification of FSO channel models using radial basis function neural networks and their ber performance with Luby transform codes
(2012) Prakash, G.; Kulkarni, M.; Sripati Acharya, U.; Kalyanpur, M.N.
Free Space Optical (FSO) communication systems offer a license free and cost effective access performance. FSO links can suffer from data packet corruption and erasure. Error control codes can help to mitigate turbulence induced fading and can improve the error performance of such links. Various statistical models have been proposed to describe the atmospheric turbulence channels. The choice of the appropriate model for varying level of turbulence is dependent on the atmospheric parameters. In this paper we classify the channels using Radial Basis Function Neural Networks to decide the best fit. We then investigate the error performance of FSO channels modeled as Gamma- Gamma and K distribution functions with Luby Transform encoding which are rateless codes. Simulation results are used to compare the performance of different modulation schemes with Luby Transform encoding and also to classify the appropriate distribution function for the channel model. © 2012 by IJAI (CESER Publications).
Energy efficient rateless codes for high speed data transfer over free space optical channels
(2015) Prakash, G.; Kulkarni, M.; Shripathi, Acharya U.
Terrestrial Free Space Optical (FSO) links transmit information by using the atmosphere (free space) as a medium. In this paper, we have investigated the use of Luby Transform (LT) codes as a means to mitigate the effects of data corruption induced by imperfect channel which usually takes the form of lost or corrupted packets. LT codes, which are a class of Fountain codes, can be used independent of the channel rate and as many code words as required can be generated to recover all the message bits irrespective of the channel performance. Achieving error free high data rates with limited energy resources is possible with FSO systems if error correction codes with minimal overheads on the power can be used. We also employ a combination of Binary Phase Shift Keying (BPSK) with provision for modification of threshold and optimized LT codes with belief propagation for decoding. These techniques provide additional protection even under strong turbulence regimes. Automatic Repeat Request (ARQ) is another method of improving link reliability. Performance of ARQ is limited by the number of retransmissions and the corresponding time delay. We prove through theoretical computations and simulations that LT codes consume less energy per bit. We validate the feasibility of using energy efficient LT codes over ARQ for FSO links to be used in optical wireless sensor networks within the eye safety limits. � 2015 SPIE.
Energy efficient rateless codes for high speed data transfer over free space optical channels
(SPIE spie@spie.org, 2015) Prakash, G.; Kulkarni, M.; Shripathi Acharya, U.S.
Terrestrial Free Space Optical (FSO) links transmit information by using the atmosphere (free space) as a medium. In this paper, we have investigated the use of Luby Transform (LT) codes as a means to mitigate the effects of data corruption induced by imperfect channel which usually takes the form of lost or corrupted packets. LT codes, which are a class of Fountain codes, can be used independent of the channel rate and as many code words as required can be generated to recover all the message bits irrespective of the channel performance. Achieving error free high data rates with limited energy resources is possible with FSO systems if error correction codes with minimal overheads on the power can be used. We also employ a combination of Binary Phase Shift Keying (BPSK) with provision for modification of threshold and optimized LT codes with belief propagation for decoding. These techniques provide additional protection even under strong turbulence regimes. Automatic Repeat Request (ARQ) is another method of improving link reliability. Performance of ARQ is limited by the number of retransmissions and the corresponding time delay. We prove through theoretical computations and simulations that LT codes consume less energy per bit. We validate the feasibility of using energy efficient LT codes over ARQ for FSO links to be used in optical wireless sensor networks within the eye safety limits. Â© 2015 SPIE.
Hidden Markov Model for Hard Disk Drive Failure Detection
(Institute of Electrical and Electronics Engineers Inc., 2024) Harish, A.; Prakash, G.; Nair, R.R.; Iyer, V.B.; Mohan, B.R.; Das, M.
Understanding disk failures is crucial for both disk manufacturers and users, enabling the production of more dependable disk drives and the establishment of robust storage systems. Detecting disk failure has been found to be facilitated by the use of observable disk properties, especially those provided by the Self-Monitoring and Reporting Technology (SMART) system. In our paper, we leverage the capabilities of the SMART time series dataset to achieve an overall accuracy of 92% in disk failure detection. Â© 2024 IEEE.
On the improved performance of luby transform codes over selective repeat ARQ in turbulent free space optical links
(2013) Prakash, G.; Nayak, A.; Kulkarni, M.; Acharya, S.
Free Space Optical (FSO) links are capable of offering high data transfer rates, secure and low interference links for connectivity as a last mile solution. However, atmospheric turbulence can degrade the performance for distances over 1 km. This degradation is in the form of packet loss and hence drop in the error performance. Error Control Coding (ECC) can be used to mitigate the effects of the atmospheric turbulence. In this paper we prove analytically and verify through simulations that Luby Transform(LT) Codes show an improved performance over Automatic Repeat Request(ARQ) schemes for FSO transmission. FSO systems are limited by the safety limits of the input power to the laser transmitter. A notable contribution in this paper is that we prove that this improvement with LT codes is within Maximum Permissible Exposure (MPE) limit for an FSO link for a BER performance of 10-5. � 2013 IEEE.
On the improved performance of luby transform codes over selective repeat ARQ in turbulent free space optical links
(2013) Prakash, G.; Nayak, A.; Kulkarni, M.; Acharya, S.
Free Space Optical (FSO) links are capable of offering high data transfer rates, secure and low interference links for connectivity as a last mile solution. However, atmospheric turbulence can degrade the performance for distances over 1 km. This degradation is in the form of packet loss and hence drop in the error performance. Error Control Coding (ECC) can be used to mitigate the effects of the atmospheric turbulence. In this paper we prove analytically and verify through simulations that Luby Transform(LT) Codes show an improved performance over Automatic Repeat Request(ARQ) schemes for FSO transmission. FSO systems are limited by the safety limits of the input power to the laser transmitter. A notable contribution in this paper is that we prove that this improvement with LT codes is within Maximum Permissible Exposure (MPE) limit for an FSO link for a BER performance of 10-5. Â© 2013 IEEE.
Performance analysis of fountain codes with Robust Soliton distribution for erasure channels
(2011) Prakash, G.; Nayak, M.; Kulkarni, M.; Shripathi, Acharya U.
Fountain Codes are essentially Forward Error Correction (FEC) codes, which were developed for applications involving multicasting or for delivering large amounts of content to multiple recipients simultaneously. FEC increases the reliability of a system in a noisy environment. Luby Transform codes (LT codes) which come from a new coding family of the Fountain codes are the first realization of rateless codes which can generate potentially limitless code words from data. In this paper, a performance analysis of Fountain codes for erasure channels, which use the Robust Soliton distribution for encoding the data packets and belief propagation to decode the received packets has been carried out Results show that the overhead during decoding is around 11.2%. � 2011 IEEE.
Performance analysis of fountain codes with Robust Soliton distribution for erasure channels
(2011) Prakash, G.; Nayak, M.; Kulkarni, M.; Sripati, U.
Fountain Codes are essentially Forward Error Correction (FEC) codes, which were developed for applications involving multicasting or for delivering large amounts of content to multiple recipients simultaneously. FEC increases the reliability of a system in a noisy environment. Luby Transform codes (LT codes) which come from a new coding family of the Fountain codes are the first realization of rateless codes which can generate potentially limitless code words from data. In this paper, a performance analysis of Fountain codes for erasure channels, which use the Robust Soliton distribution for encoding the data packets and belief propagation to decode the received packets has been carried out Results show that the overhead during decoding is around 11.2%. Â© 2011 IEEE.
Performance analysis of Free Space Optical links encoded using Luby Transform codes
(2012) Prakash, G.; Kulkarni, M.; Shripathi, Acharya U.; Kalyanpur, M.N.
Free Space Optical (FSO) communication is an emerging transmission technique to transmit high data rates without using cables. This technology is expected to revolutionize the present communication system architectures both in the terrestrial and the in -space architecture. Atmospheric effects can significantly degrade the performance of FSO systems. This reduces the SNR and leads to impaired performance. FSO channels can be modeled using Gamma-Gamma, Weibull, Log-Normal, K distribution functions. Error control codes can help to mitigate atmospheric turbulence induced signal fading in free space optical communication links. Luby Transform codes belong to a class of error control codes called Fountain codes and are meant for erasure channels. In this paper, we propose encoding FSO links with Luby Transform (LT) codes for error channels. Decoding is done using belief propagation with Log Likelihood Ratio and results are obtained for different modulation schemes under different channel distributions. � 2012 IEEE.
Performance analysis of Free Space Optical links encoded using Luby Transform codes
(2012) Prakash, G.; Kulkarni, M.; Sripati, U.; Kalyanpur, M.N.
Free Space Optical (FSO) communication is an emerging transmission technique to transmit high data rates without using cables. This technology is expected to revolutionize the present communication system architectures both in the terrestrial and the in -space architecture. Atmospheric effects can significantly degrade the performance of FSO systems. This reduces the SNR and leads to impaired performance. FSO channels can be modeled using Gamma-Gamma, Weibull, Log-Normal, K distribution functions. Error control codes can help to mitigate atmospheric turbulence induced signal fading in free space optical communication links. Luby Transform codes belong to a class of error control codes called Fountain codes and are meant for erasure channels. In this paper, we propose encoding FSO links with Luby Transform (LT) codes for error channels. Decoding is done using belief propagation with Log Likelihood Ratio and results are obtained for different modulation schemes under different channel distributions. Â© 2012 IEEE.
Refining LLMs with Reinforcement Learning for Human-Like Text Generation
(Institute of Electrical and Electronics Engineers Inc., 2024) Harish, A.; Prakash, G.; Nair, R.R.; Iyer, V.B.; Anand Kumar, M.
Large Language Models (LLMs) are used widely for tasks involving text generation such as dialogue summarization and creative writing. The generated text often appears unnatural, and this text can easily be distinguished from natural language. In this paper, we leverage the capabilities of Reinforcement Learning to fine-tune LLMs so as to produce text that resembles human language. We have applied the Proximal Policy Optimization algorithm to fine tune a FLAN-T5 LLM for a dialogue summarization task. Â© 2024 IEEE.
Using RBF neural networks and kullback-leibler distance to classify channel models in Free Space Optics
(2012) Prakash, G.; Kulkarni, M.; Shripathi, Acharya U.
Free Space Optical (FSO) communication systems offer a license free and cost effective access performance. FSO systems provide virtually unlimited bandwidth. Since the laser beams used in these systems are spatially confined, the links are very secure. However FSO links perform well only in clear weather conditions. Clouds, fog, aerosols, and turbulence drastically affect the performance of FSO systems and lead to fluctuations in both the intensity and phase of the received signal. FSO links can suffer from data packet corruption and erasure. Various statistical models have been proposed to describe the atmospheric turbulence channels. The choice of the appropriate model for varying level of turbulence is dependent on the atmospheric parameters. In this paper we classify the channels using Radial Basis Function Neural Networks to decide the best fit. We also use Kullback-Leibler distance as a measure between the reference distribution and the distribution of observed data. � 2012 IEEE.
Using RBF neural networks and kullback-leibler distance to classify channel models in Free Space Optics
(2012) Prakash, G.; Kulkarni, M.; Sripati, U.
Free Space Optical (FSO) communication systems offer a license free and cost effective access performance. FSO systems provide virtually unlimited bandwidth. Since the laser beams used in these systems are spatially confined, the links are very secure. However FSO links perform well only in clear weather conditions. Clouds, fog, aerosols, and turbulence drastically affect the performance of FSO systems and lead to fluctuations in both the intensity and phase of the received signal. FSO links can suffer from data packet corruption and erasure. Various statistical models have been proposed to describe the atmospheric turbulence channels. The choice of the appropriate model for varying level of turbulence is dependent on the atmospheric parameters. In this paper we classify the channels using Radial Basis Function Neural Networks to decide the best fit. We also use Kullback-Leibler distance as a measure between the reference distribution and the distribution of observed data. Â© 2012 IEEE.