This document discusses various topics related to data communication and digital transmission. It begins by defining data communication as the exchange of data between two devices. It then discusses attributes of data communication like delivery, accuracy, timeliness and jitter. It also covers components of communication systems, data representation formats, direction of data flow, physical structures and topologies. The document further explains concepts like switching, data and signal types, line coding schemes, transmission impairments, data rate limits, and performance metrics such as bandwidth, throughput, latency and jitter. Finally, it provides an overview of analog to digital conversion techniques like PCM sampling, quantization and encoding.
Simulation of Direct Sequence Spread Spectrum for Wireless Communication Syst...ijtsrd
In this work, a simulation model for Direct Sequence Spread Spectrum (DSSS) scheme for wireless communication systems has been proposed. Unlike the case of a single frequency carrier, the modulated signal in DSSS occupies a much wider bandwidth in order to reduce the possible interferences with narrow band communication signals. In telecommunications, DSSS is a spread spectrum modulation technique used to reduce overall signal interference. The spreading of this signal makes the resulting wideband channel more noisy, allowing for greater resistance to unintentional and intentional interference. Y.V.S Durga Prasad | K. Venkateswarlu"Simulation of Direct Sequence Spread Spectrum for Wireless Communication Systems using Simulink" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-2 | Issue-4 , June 2018, URL: http://www.ijtsrd.com/papers/ijtsrd14118.pdf http://www.ijtsrd.com/engineering/electronics-and-communication-engineering/14118/simulation-of-direct-sequence-spread-spectrum-for-wireless-communication-systems-using-simulink/yvs-durga-prasad
Data Compression using Multiple Transformation Techniques for Audio Applicati...iosrjce
IOSR Journal of Computer Engineering (IOSR-JCE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of computer engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in computer technology. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Noise Analysis on Indoor Power Line Communication Channelijsrd.com
The power line communication technology is now considered as a good alternative for the implementing communication network. Digital networks can be established using the same set of wires that is use to distribute the power signal through the power-line channel(PLC) because power line networks are excellent infrastructure for broadband data transmission however various noise exist due to stochastic change in the network load impedance. This paper is an attempt to identify different type of noise in PLC channel and investigate the performance of indoor channel of PLC system. The noise seen in the power-line channel varies with frequency, time and from line to line .in this paper we classify different type of noises its characteristics and the process to remove it from power line channel.
PAPR Reduction using Tone Reservation Method in OFDM SignalIJASRD Journal
In this paper, we are going to propose ‘Tone Reservation’ technique to reduce PAPR (Peak to Average Power Ratio) in OFDM signal using new algorithm. It is less complex and also calculates its own threshold value at the time of communication. It also calculates its PRT signal while other algorithms requiring predetermined threshold and PRT. It modifies the data by ‘bit by bit’ comparison with a modified copy of itself (algorithm modified) thus scaling the peaks as and providing a decent BER and good PAPR reduction.
DATA HIDING IN AUDIO SIGNALS USING WAVELET TRANSFORM WITH ENHANCED SECURITYcsandit
Rapid increase in data transmission over internet results in emphasis on information security.
Audio steganography is used for secure transmission of secret data with audio signal as the
carrier. In the proposed method, cover audio file is transformed from space domain to wavelet
domain using lifting scheme, leading to secure data hiding. Text message is encrypted using
dynamic encryption algorithm. Cipher text is then hidden in wavelet coefficients of cover audio
signal. Signal to Noise Ratio (SNR) and Squared Pearson Correlation Coefficient (SPCC)
values are computed to judge the quality of the stego audio signal. Results show that stego
audio signal is perceptually indistinguishable from the cover audio signal. Stego audio signal is
robust even in presence of external noise. Proposed method provides secure and least error
data extraction.
On the use of voice activity detection in speech emotion recognitionjournalBEEI
Emotion recognition through speech has many potential applications, however the challenge comes from achieving a high emotion recognition while using limited resources or interference such as noise. In this paper we have explored the possibility of improving speech emotion recognition by utilizing the voice activity detection (VAD) concept. The emotional voice data from the Berlin Emotion Database (EMO-DB) and a custom-made database LQ Audio Dataset are firstly preprocessed by VAD before feature extraction. The features are then passed to the deep neural network for classification. In this paper, we have chosen MFCC to be the sole determinant feature. From the results obtained using VAD and without, we have found that the VAD improved the recognition rate of 5 emotions (happy, angry, sad, fear, and neutral) by 3.7% when recognizing clean signals, while the effect of using VAD when training a network with both clean and noisy signals improved our previous results by 50%.
3. speech processing algorithms for perception improvement of hearing impaire...k srikanth
This document presents a novel algorithm to improve speech perception for hearing impaired patients using dichotic speech processing and presentation techniques. The algorithm splits speech into multiple frequency bands using dyadic filters to achieve bands of constant bandwidth, 1/3 octave bandwidth, and critical bandwidth. Listening tests on 5 subjects with hearing loss were conducted using 15 syllable speech material processed with the different filter sets. The results showed that processing with 1/3 octave bands improved recognition scores and reduced response times the most compared to unprocessed speech and speech processed with the other two filter sets. The algorithm aims to overcome issues like spectral and temporal masking that impair speech perception for those with sensorineural hearing loss.
This document proposes modifications to the physical and data link layers to improve resistance against jamming attacks in wireless sensor networks. In the physical layer, an uncorrelated groups based direct sequence spread spectrum technique is proposed where sequences are grouped and selected randomly to spread messages. In the data link layer, two modifications to the SMAC protocol are proposed: 1) Data Packet Separation Slot Size Randomization, which separates data packets to mislead jammers' estimation of slot size, forcing them to deplete power more quickly. 2) Maximum Covers using Mixed Integer Programming algorithm, which aims to minimize energy consumption while scheduling network tasks. Simulation results show the proposed techniques can achieve over 8% reduction in an attacker's lifetime advantage compared to
Simulation of Direct Sequence Spread Spectrum for Wireless Communication Syst...ijtsrd
In this work, a simulation model for Direct Sequence Spread Spectrum (DSSS) scheme for wireless communication systems has been proposed. Unlike the case of a single frequency carrier, the modulated signal in DSSS occupies a much wider bandwidth in order to reduce the possible interferences with narrow band communication signals. In telecommunications, DSSS is a spread spectrum modulation technique used to reduce overall signal interference. The spreading of this signal makes the resulting wideband channel more noisy, allowing for greater resistance to unintentional and intentional interference. Y.V.S Durga Prasad | K. Venkateswarlu"Simulation of Direct Sequence Spread Spectrum for Wireless Communication Systems using Simulink" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-2 | Issue-4 , June 2018, URL: http://www.ijtsrd.com/papers/ijtsrd14118.pdf http://www.ijtsrd.com/engineering/electronics-and-communication-engineering/14118/simulation-of-direct-sequence-spread-spectrum-for-wireless-communication-systems-using-simulink/yvs-durga-prasad
Data Compression using Multiple Transformation Techniques for Audio Applicati...iosrjce
IOSR Journal of Computer Engineering (IOSR-JCE) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of computer engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in computer technology. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Noise Analysis on Indoor Power Line Communication Channelijsrd.com
The power line communication technology is now considered as a good alternative for the implementing communication network. Digital networks can be established using the same set of wires that is use to distribute the power signal through the power-line channel(PLC) because power line networks are excellent infrastructure for broadband data transmission however various noise exist due to stochastic change in the network load impedance. This paper is an attempt to identify different type of noise in PLC channel and investigate the performance of indoor channel of PLC system. The noise seen in the power-line channel varies with frequency, time and from line to line .in this paper we classify different type of noises its characteristics and the process to remove it from power line channel.
PAPR Reduction using Tone Reservation Method in OFDM SignalIJASRD Journal
In this paper, we are going to propose ‘Tone Reservation’ technique to reduce PAPR (Peak to Average Power Ratio) in OFDM signal using new algorithm. It is less complex and also calculates its own threshold value at the time of communication. It also calculates its PRT signal while other algorithms requiring predetermined threshold and PRT. It modifies the data by ‘bit by bit’ comparison with a modified copy of itself (algorithm modified) thus scaling the peaks as and providing a decent BER and good PAPR reduction.
DATA HIDING IN AUDIO SIGNALS USING WAVELET TRANSFORM WITH ENHANCED SECURITYcsandit
Rapid increase in data transmission over internet results in emphasis on information security.
Audio steganography is used for secure transmission of secret data with audio signal as the
carrier. In the proposed method, cover audio file is transformed from space domain to wavelet
domain using lifting scheme, leading to secure data hiding. Text message is encrypted using
dynamic encryption algorithm. Cipher text is then hidden in wavelet coefficients of cover audio
signal. Signal to Noise Ratio (SNR) and Squared Pearson Correlation Coefficient (SPCC)
values are computed to judge the quality of the stego audio signal. Results show that stego
audio signal is perceptually indistinguishable from the cover audio signal. Stego audio signal is
robust even in presence of external noise. Proposed method provides secure and least error
data extraction.
On the use of voice activity detection in speech emotion recognitionjournalBEEI
Emotion recognition through speech has many potential applications, however the challenge comes from achieving a high emotion recognition while using limited resources or interference such as noise. In this paper we have explored the possibility of improving speech emotion recognition by utilizing the voice activity detection (VAD) concept. The emotional voice data from the Berlin Emotion Database (EMO-DB) and a custom-made database LQ Audio Dataset are firstly preprocessed by VAD before feature extraction. The features are then passed to the deep neural network for classification. In this paper, we have chosen MFCC to be the sole determinant feature. From the results obtained using VAD and without, we have found that the VAD improved the recognition rate of 5 emotions (happy, angry, sad, fear, and neutral) by 3.7% when recognizing clean signals, while the effect of using VAD when training a network with both clean and noisy signals improved our previous results by 50%.
3. speech processing algorithms for perception improvement of hearing impaire...k srikanth
This document presents a novel algorithm to improve speech perception for hearing impaired patients using dichotic speech processing and presentation techniques. The algorithm splits speech into multiple frequency bands using dyadic filters to achieve bands of constant bandwidth, 1/3 octave bandwidth, and critical bandwidth. Listening tests on 5 subjects with hearing loss were conducted using 15 syllable speech material processed with the different filter sets. The results showed that processing with 1/3 octave bands improved recognition scores and reduced response times the most compared to unprocessed speech and speech processed with the other two filter sets. The algorithm aims to overcome issues like spectral and temporal masking that impair speech perception for those with sensorineural hearing loss.
This document proposes modifications to the physical and data link layers to improve resistance against jamming attacks in wireless sensor networks. In the physical layer, an uncorrelated groups based direct sequence spread spectrum technique is proposed where sequences are grouped and selected randomly to spread messages. In the data link layer, two modifications to the SMAC protocol are proposed: 1) Data Packet Separation Slot Size Randomization, which separates data packets to mislead jammers' estimation of slot size, forcing them to deplete power more quickly. 2) Maximum Covers using Mixed Integer Programming algorithm, which aims to minimize energy consumption while scheduling network tasks. Simulation results show the proposed techniques can achieve over 8% reduction in an attacker's lifetime advantage compared to
Artificial Intelligence Based Mutual Authentication Technique with Four Entit...IDES Editor
4-G mobile communications system has utilized
high speed data communications technology having
connectivity to all sorts of networks including 2-G and 3-G
mobile networks. Authentication of mobile subscribers and
networks are a prime criterion to check and minimize security
threats and attacks. An artificial intelligence based mutual
authentication system with four entities is proposed. A person
talking salutation or greeting words in different times are
always consisting of a very narrow range of frequencies which
are varying in nature from person to person. Voice frequency
of the salutation or selective words used by a subscriber like
Hello, Good Morning etc is taken as first entity. Second entity
is chosen as frequency of flipping or clapping sound of the
calling subscriber. Then third entity is taken as face image of
the calling subscriber. Fourth entity is granted as probability
of salutation or greeting word from subscriber’s talking habit
(set of salutation words) while initializing a call. These four
entities such as probability of particular range of frequencies
for the salutation word, frequency of flipping sound, face
image matching of the subscriber, particular salutation or
greeting word at the time of starting a call are used with most
frequently, more frequently and less frequently by the calling
subscriber like uncertainty in Artificial Intelligence (AI). Now
different relative grades are assigned for most frequently,
more frequently and less frequently used parameters and the
grades are modified according to the assumed weightage. A
Fuzzy Rule (condition) by Fuzzy operation is invented. If the
results obtained from fuzzy operations are satisfied by the
fuzzy rule, the subscriber (MS) and the network (Switch or
Server) are mutually authenticated in 4-G mobile
communications.
Analysis of PEAQ Model using Wavelet Decomposition Techniquesidescitation
Digital broadcasting, internet audio and music database make use of audio
compression and coding techniques to reduce high quality audio signal without impairing its
perceptual quality. Audio signal compression is the lossy compression
technique, It
converts original converting audio signal into compressed bitstream. The compressed audio
bitstream is decoded at the decoder to produce a close approximation of the original signal.
For the purpose of improving the coding this work attempts to verify the perceptual
evaluation of audio quality (PEAQ) model in BS.1387 using wavelet decomposition
techniques. Finally the comparison of masking threshold for sub-bands using Wavelet
techniques and Fast Fourier transform (FFT) will be done
Speech Emotion Recognition is a recent research topic in the Human Computer Interaction (HCI) field. The need has risen for a more natural communication interface between humans and computer, as computers have become an integral part of our lives. A lot of work currently going on to improve the interaction between humans and computers. To achieve this goal, a computer would have to be able to distinguish its present situation and respond differently depending on that observation. Part of this process involves understanding a user‟s emotional state. To make the human computer interaction more natural, the objective is that computer should be able to recognize emotional states in the same as human does. The efficiency of emotion recognition system depends on type of features extracted and classifier used for detection of emotions. The proposed system aims at identification of basic emotional states such as anger, joy, neutral and sadness from human speech. While classifying different emotions, features like MFCC (Mel Frequency Cepstral Coefficient) and Energy is used. In this paper, Standard Emotional Database i.e. English Database is used which gives the satisfactory detection of emotions than recorded samples of emotions. This methodology describes and compares the performances of Learning Vector Quantization Neural Network (LVQ NN), Multiclass Support Vector Machine (SVM) and their combination for emotion recognition.
Design of dfe based mimo communication system for mobile moving with high vel...Made Artha
The document discusses the design of a decision feedback equalizer (DFE) based multiple-input multiple-output (MIMO) communication system for mobile receivers moving at high velocities of up to 250km/hr. It analyzes the time dispersive and frequency dispersive effects of fading channels on signals. A DFE is proposed whose weights are periodically updated using the least mean squares (LMS) algorithm based on statistical channel parameters to combat the effects of fading. Simulation results show that the proposed MIMO system with a DFE achieves bit error rates below 10-3 at signal-to-noise ratios of 4dB and 10-4 at 6dB, even when the receiver is moving at 250km/hr.
This document summarizes a research paper on speech enhancement using the signal subspace algorithm. It begins with an abstract describing how noise degrades speech quality and intelligibility in communication systems. It then provides background on speech enhancement objectives and commonly used methods like spectral subtraction and signal subspace. The paper describes the signal subspace algorithm and shows its ability to enhance speech signals by suppressing noise. Experimental results on sine waves with added Gaussian noise demonstrate improved peak signal-to-noise ratios when using the signal subspace method compared to the noisy signals. The conclusion is that the algorithm removes noise to a great extent from noisy speech.
Speech signal analysis for linear filter banks of different orderseSAT Journals
Abstract In speech signal processing using of filter banks is very important. The critical requirement is the sum of all the frequency responses of the band-pass filters of the filter bank i.e. composite frequency response be flat with linear phase. This paper deals with design and implementation of linear-phase FIR digital filters based filter bank flat with flat composite frequency response. The design is based on special properties of FIR filters by which excellent frequency response can be achieved. Keyword: Speech signal, FIR Filter, Composite frequency response.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Analysis of Microstrip Finger on Bandwidth of Interdigital Band Pass Filter u...IJREST
This document discusses using artificial neural networks to estimate the bandwidth of an interdigital band pass filter based on variations in the finger length. An ANN model was developed using data from electromagnetic simulations of filters with finger lengths ranging from 34mm to 24mm. Both multi-layer perceptron and radial basis function networks were tested, with the RBF network providing more accurate results with a mean squared error of 1.13173e-005. The proposed ANN approach allows estimating the filter bandwidth without complex calculations and provides a fast design method for interdigital band pass filters.
(1) The document proposes an energy efficient protocol for wireless sensor networks (WSNs) that employs replicated data sinks to achieve resiliency against data sink failures and efficient storage and retrieval of sensor data.
(2) It introduces a simple address assignment scheme that partitions the sensor field into cells, with each cell containing one data sink and sensors closest to that sink. This scheme is scalable and resilient against data sink and sensor node failures.
(3) The protocol uses five types of messages and a routing approach based on de Bruijn digraphs to minimize energy consumption during data transmission between sensors and sinks. It aims to maximize the lifetime of the sensor network.
VOWEL PHONEME RECOGNITION BASED ON AVERAGE ENERGY INFORMATION IN THE ZEROCROS...ijistjournal
Speech signal is modelled using the average energy of the signal in the zerocrossing intervals. Variation of these energies in the zerocrossing interval of the signal is studied and the distribution of this parameter through out the signal is evaluated. It is observed that the distribution patterns are similar for repeated utterances of the same vowels and varies from vowel to vowel. Credibility of the proposed parameter is verified over five Malayalam (one of the most popular Indian language) vowels using multilayer feed forward artificial neural network based recognition system. The performance of the system using additive white Gaussian noise corrupted speech is also studied for different SNR levels. From the experimental results it is evident that the average energy information in the zerocrossing intervals and its distributions can be effectively utilised for vowel phone classification and recognition.
Noise reduction in speech processing using improved active noise control (anc...eSAT Journals
Abstract An improved feed forward adaptive Active Noise Control (ANC) scheme is proposed by using Voice Activity Detector (VAD) and wiener filtering method. The ‘speech-plus-noise’ periods and ‘noise-only’ periods are separated using VAD and the unwanted noise is removed by adaptive filtering method. By using Speech Distortion Weighted- Multichannel Wiener Filtering (SDW-MWF) algorithm the noise periods which is present along with the speech signal, is processed and filtered out. The background noise along with the speech samples are removed by the iterative procedure of filtering process. Feed forward based ANC is used to achieve a system with a better noise reduction in speech processing. Adaptive filtering process is carried out and the speech signal without the background noise can be achieved. Key Words: Active Noise Control (ANC), Noise reduction, Adaptive filtering, Feed forward ANC
Noise reduction in speech processing using improved active noise control (anc...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
This document summarizes and compares existing routing protocols for delay tolerant networks. It presents routing protocols such as first contact, direct delivery, PROPHET, spray and wait, and epidemic routing. It also proposes a new dynamic spray and wait protocol that considers the quality of nodes based on their activity level. Simulation results show that the proposed algorithm that considers message size, number of copies, and time to live performs better than the traditional drop front approach in terms of delivery probability, buffer time average, overhead ratio, packets dropped, and hop count average.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Modeling and prevention of cell counting based attacks on toreSAT Journals
Abstract Many anonymous networks came into existence. For instance Tor allows its users to gain access to services anonymously. This network causes most of the attacks as the adversaries can hide their identity and make attacks successfully from a remote place. By making a new attack on Tor can find the vulnerability of the Tor. Ling et al. presented a new cell counting mechanism for making an attack on Tor. In this paper we implemented a custom simulator that models a Tor and demonstrates the cell counting attack by simulating nodes like sender, receiver, onion router and attacker. The experimental results revealed that the proposed attack mechanism is effective. Keywords: Anonymous network, Tor, attacker model, cell counting
Adaptive wavelet thresholding with robust hybrid features for text-independe...IJECEIAES
The robustness of speaker identification system over additive noise channel is crucial for real-world applications. In speaker identification (SID) systems, the extracted features from each speech frame are an essential factor for building a reliable identification system. For clean environments, the identification system works well; in noisy environments, there is an additive noise, which is affect the system. To eliminate the problem of additive noise and to achieve a high accuracy in speaker identification system a proposed algorithm for feature extraction based on speech enhancement and a combined features is presents. In this paper, a wavelet thresholding pre-processing stage, and feature warping (FW) techniques are used with two combined features named power normalized cepstral coefficients (PNCC) and gammatone frequency cepstral coefficients (GFCC) to improve the identification system robustness against different types of additive noises. Universal background model Gaussian mixture model (UBM-GMM) is used for features matching between the claim and actual speakers. The results showed performance improvement for the proposed feature extraction algorithm of identification system comparing with conventional features over most types of noises and different SNR ratios.
Network Lifetime Enhancement by Node Deployment in WSNIJTET Journal
Abstract— The key challenge in wireless sensor network is network lifetime so it is necessary to increase the network lifetime. The work deals with the enhancement of the network lifetime for target coverage problem in wireless sensor network while deploying the sensor nodes. Initially sensor nodes and targets are placed randomly, where the targets are the not sensor nodes its external parameter. Network lifetime for this scenario is computed, where the sensing range and initial energy of the battery are assumed. Network lifetime is based on sensor nodes that monitor the targets and lifetime of battery. The randomly placed sensor nodes are redeployed using optimization algorithm called Artificial Bee Colony (ABC). The network lifetime for redeployed sensor nodes are computed and compared with randomly deployed sensor nodes.
ELH – 3.1: ADVANCED DIGITAL COMMUNICATION UNIT – I Digital modulation techniq...Kuvempu University
Digital modulation techniques: Digital modulation formats, Coherent binary modulation techniques, Coherent quadrature – modulation techniques, Non-coherent binary modulation techniques, Comparison of binary and quaternary modulation techniques, M-ray modulation techniques, Power spectra, Bandwidth efficiency, M-array modulation formats viewed in the light of the channel capacity theorem, Effect of inter symbol interference, Bit verses symbol error probabilities, Synchronization, Applications.
This document contains 25 questions and answers related to basic electronics and communication engineering. It covers topics such as the definitions of electronics, communication, engineering, and modulation. It also discusses different communication techniques like analog and digital, as well as modulation methods like AM, FM, and more. Additionally, it provides explanations for concepts like sampling, cut-off frequency, passband, stopband, and base stations.
Pulse Compression Method for Radar Signal ProcessingEditor IJCATR
One fundamental issue in designing a good radar system is it’s capability to resolve two small targets that are located at
long range with very small separation between them. Pulse compression techniques are used in radar systems to avail the benefits
of large range detection capability of long duration pulse and high range resolution capability of short duration pulse. In these
techniques a long duration pulse is used which is frequency modulated before transmission and the received signal is passed through a
match filter to accumulate the energy into a short pulse. A matched filter is used for pulse compression to achieve high signal-to-noise
ratio (SNR). Two important factors to be considered for radar waveform design are range resolution and maximum range detection.
Range resolution is the ability of the radar to separate closely spaced targets and it is related to the pulse width of the waveform. The
narrower the pulse width the better is the range resolution. But, if the pulse width is decreased, the amount of energy in the pulse is
decreased and hence maximum range detection gets reduced. To overcome this problem pulse compression techniques are used in the
radar systems. In this paper, the pulse compression technique is described to resolve two small targets that are located at long
range with very small separation between them.
Artificial Intelligence Based Mutual Authentication Technique with Four Entit...IDES Editor
4-G mobile communications system has utilized
high speed data communications technology having
connectivity to all sorts of networks including 2-G and 3-G
mobile networks. Authentication of mobile subscribers and
networks are a prime criterion to check and minimize security
threats and attacks. An artificial intelligence based mutual
authentication system with four entities is proposed. A person
talking salutation or greeting words in different times are
always consisting of a very narrow range of frequencies which
are varying in nature from person to person. Voice frequency
of the salutation or selective words used by a subscriber like
Hello, Good Morning etc is taken as first entity. Second entity
is chosen as frequency of flipping or clapping sound of the
calling subscriber. Then third entity is taken as face image of
the calling subscriber. Fourth entity is granted as probability
of salutation or greeting word from subscriber’s talking habit
(set of salutation words) while initializing a call. These four
entities such as probability of particular range of frequencies
for the salutation word, frequency of flipping sound, face
image matching of the subscriber, particular salutation or
greeting word at the time of starting a call are used with most
frequently, more frequently and less frequently by the calling
subscriber like uncertainty in Artificial Intelligence (AI). Now
different relative grades are assigned for most frequently,
more frequently and less frequently used parameters and the
grades are modified according to the assumed weightage. A
Fuzzy Rule (condition) by Fuzzy operation is invented. If the
results obtained from fuzzy operations are satisfied by the
fuzzy rule, the subscriber (MS) and the network (Switch or
Server) are mutually authenticated in 4-G mobile
communications.
Analysis of PEAQ Model using Wavelet Decomposition Techniquesidescitation
Digital broadcasting, internet audio and music database make use of audio
compression and coding techniques to reduce high quality audio signal without impairing its
perceptual quality. Audio signal compression is the lossy compression
technique, It
converts original converting audio signal into compressed bitstream. The compressed audio
bitstream is decoded at the decoder to produce a close approximation of the original signal.
For the purpose of improving the coding this work attempts to verify the perceptual
evaluation of audio quality (PEAQ) model in BS.1387 using wavelet decomposition
techniques. Finally the comparison of masking threshold for sub-bands using Wavelet
techniques and Fast Fourier transform (FFT) will be done
Speech Emotion Recognition is a recent research topic in the Human Computer Interaction (HCI) field. The need has risen for a more natural communication interface between humans and computer, as computers have become an integral part of our lives. A lot of work currently going on to improve the interaction between humans and computers. To achieve this goal, a computer would have to be able to distinguish its present situation and respond differently depending on that observation. Part of this process involves understanding a user‟s emotional state. To make the human computer interaction more natural, the objective is that computer should be able to recognize emotional states in the same as human does. The efficiency of emotion recognition system depends on type of features extracted and classifier used for detection of emotions. The proposed system aims at identification of basic emotional states such as anger, joy, neutral and sadness from human speech. While classifying different emotions, features like MFCC (Mel Frequency Cepstral Coefficient) and Energy is used. In this paper, Standard Emotional Database i.e. English Database is used which gives the satisfactory detection of emotions than recorded samples of emotions. This methodology describes and compares the performances of Learning Vector Quantization Neural Network (LVQ NN), Multiclass Support Vector Machine (SVM) and their combination for emotion recognition.
Design of dfe based mimo communication system for mobile moving with high vel...Made Artha
The document discusses the design of a decision feedback equalizer (DFE) based multiple-input multiple-output (MIMO) communication system for mobile receivers moving at high velocities of up to 250km/hr. It analyzes the time dispersive and frequency dispersive effects of fading channels on signals. A DFE is proposed whose weights are periodically updated using the least mean squares (LMS) algorithm based on statistical channel parameters to combat the effects of fading. Simulation results show that the proposed MIMO system with a DFE achieves bit error rates below 10-3 at signal-to-noise ratios of 4dB and 10-4 at 6dB, even when the receiver is moving at 250km/hr.
This document summarizes a research paper on speech enhancement using the signal subspace algorithm. It begins with an abstract describing how noise degrades speech quality and intelligibility in communication systems. It then provides background on speech enhancement objectives and commonly used methods like spectral subtraction and signal subspace. The paper describes the signal subspace algorithm and shows its ability to enhance speech signals by suppressing noise. Experimental results on sine waves with added Gaussian noise demonstrate improved peak signal-to-noise ratios when using the signal subspace method compared to the noisy signals. The conclusion is that the algorithm removes noise to a great extent from noisy speech.
Speech signal analysis for linear filter banks of different orderseSAT Journals
Abstract In speech signal processing using of filter banks is very important. The critical requirement is the sum of all the frequency responses of the band-pass filters of the filter bank i.e. composite frequency response be flat with linear phase. This paper deals with design and implementation of linear-phase FIR digital filters based filter bank flat with flat composite frequency response. The design is based on special properties of FIR filters by which excellent frequency response can be achieved. Keyword: Speech signal, FIR Filter, Composite frequency response.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Analysis of Microstrip Finger on Bandwidth of Interdigital Band Pass Filter u...IJREST
This document discusses using artificial neural networks to estimate the bandwidth of an interdigital band pass filter based on variations in the finger length. An ANN model was developed using data from electromagnetic simulations of filters with finger lengths ranging from 34mm to 24mm. Both multi-layer perceptron and radial basis function networks were tested, with the RBF network providing more accurate results with a mean squared error of 1.13173e-005. The proposed ANN approach allows estimating the filter bandwidth without complex calculations and provides a fast design method for interdigital band pass filters.
(1) The document proposes an energy efficient protocol for wireless sensor networks (WSNs) that employs replicated data sinks to achieve resiliency against data sink failures and efficient storage and retrieval of sensor data.
(2) It introduces a simple address assignment scheme that partitions the sensor field into cells, with each cell containing one data sink and sensors closest to that sink. This scheme is scalable and resilient against data sink and sensor node failures.
(3) The protocol uses five types of messages and a routing approach based on de Bruijn digraphs to minimize energy consumption during data transmission between sensors and sinks. It aims to maximize the lifetime of the sensor network.
VOWEL PHONEME RECOGNITION BASED ON AVERAGE ENERGY INFORMATION IN THE ZEROCROS...ijistjournal
Speech signal is modelled using the average energy of the signal in the zerocrossing intervals. Variation of these energies in the zerocrossing interval of the signal is studied and the distribution of this parameter through out the signal is evaluated. It is observed that the distribution patterns are similar for repeated utterances of the same vowels and varies from vowel to vowel. Credibility of the proposed parameter is verified over five Malayalam (one of the most popular Indian language) vowels using multilayer feed forward artificial neural network based recognition system. The performance of the system using additive white Gaussian noise corrupted speech is also studied for different SNR levels. From the experimental results it is evident that the average energy information in the zerocrossing intervals and its distributions can be effectively utilised for vowel phone classification and recognition.
Noise reduction in speech processing using improved active noise control (anc...eSAT Journals
Abstract An improved feed forward adaptive Active Noise Control (ANC) scheme is proposed by using Voice Activity Detector (VAD) and wiener filtering method. The ‘speech-plus-noise’ periods and ‘noise-only’ periods are separated using VAD and the unwanted noise is removed by adaptive filtering method. By using Speech Distortion Weighted- Multichannel Wiener Filtering (SDW-MWF) algorithm the noise periods which is present along with the speech signal, is processed and filtered out. The background noise along with the speech samples are removed by the iterative procedure of filtering process. Feed forward based ANC is used to achieve a system with a better noise reduction in speech processing. Adaptive filtering process is carried out and the speech signal without the background noise can be achieved. Key Words: Active Noise Control (ANC), Noise reduction, Adaptive filtering, Feed forward ANC
Noise reduction in speech processing using improved active noise control (anc...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
This document summarizes and compares existing routing protocols for delay tolerant networks. It presents routing protocols such as first contact, direct delivery, PROPHET, spray and wait, and epidemic routing. It also proposes a new dynamic spray and wait protocol that considers the quality of nodes based on their activity level. Simulation results show that the proposed algorithm that considers message size, number of copies, and time to live performs better than the traditional drop front approach in terms of delivery probability, buffer time average, overhead ratio, packets dropped, and hop count average.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Modeling and prevention of cell counting based attacks on toreSAT Journals
Abstract Many anonymous networks came into existence. For instance Tor allows its users to gain access to services anonymously. This network causes most of the attacks as the adversaries can hide their identity and make attacks successfully from a remote place. By making a new attack on Tor can find the vulnerability of the Tor. Ling et al. presented a new cell counting mechanism for making an attack on Tor. In this paper we implemented a custom simulator that models a Tor and demonstrates the cell counting attack by simulating nodes like sender, receiver, onion router and attacker. The experimental results revealed that the proposed attack mechanism is effective. Keywords: Anonymous network, Tor, attacker model, cell counting
Adaptive wavelet thresholding with robust hybrid features for text-independe...IJECEIAES
The robustness of speaker identification system over additive noise channel is crucial for real-world applications. In speaker identification (SID) systems, the extracted features from each speech frame are an essential factor for building a reliable identification system. For clean environments, the identification system works well; in noisy environments, there is an additive noise, which is affect the system. To eliminate the problem of additive noise and to achieve a high accuracy in speaker identification system a proposed algorithm for feature extraction based on speech enhancement and a combined features is presents. In this paper, a wavelet thresholding pre-processing stage, and feature warping (FW) techniques are used with two combined features named power normalized cepstral coefficients (PNCC) and gammatone frequency cepstral coefficients (GFCC) to improve the identification system robustness against different types of additive noises. Universal background model Gaussian mixture model (UBM-GMM) is used for features matching between the claim and actual speakers. The results showed performance improvement for the proposed feature extraction algorithm of identification system comparing with conventional features over most types of noises and different SNR ratios.
Network Lifetime Enhancement by Node Deployment in WSNIJTET Journal
Abstract— The key challenge in wireless sensor network is network lifetime so it is necessary to increase the network lifetime. The work deals with the enhancement of the network lifetime for target coverage problem in wireless sensor network while deploying the sensor nodes. Initially sensor nodes and targets are placed randomly, where the targets are the not sensor nodes its external parameter. Network lifetime for this scenario is computed, where the sensing range and initial energy of the battery are assumed. Network lifetime is based on sensor nodes that monitor the targets and lifetime of battery. The randomly placed sensor nodes are redeployed using optimization algorithm called Artificial Bee Colony (ABC). The network lifetime for redeployed sensor nodes are computed and compared with randomly deployed sensor nodes.
ELH – 3.1: ADVANCED DIGITAL COMMUNICATION UNIT – I Digital modulation techniq...Kuvempu University
Digital modulation techniques: Digital modulation formats, Coherent binary modulation techniques, Coherent quadrature – modulation techniques, Non-coherent binary modulation techniques, Comparison of binary and quaternary modulation techniques, M-ray modulation techniques, Power spectra, Bandwidth efficiency, M-array modulation formats viewed in the light of the channel capacity theorem, Effect of inter symbol interference, Bit verses symbol error probabilities, Synchronization, Applications.
This document contains 25 questions and answers related to basic electronics and communication engineering. It covers topics such as the definitions of electronics, communication, engineering, and modulation. It also discusses different communication techniques like analog and digital, as well as modulation methods like AM, FM, and more. Additionally, it provides explanations for concepts like sampling, cut-off frequency, passband, stopband, and base stations.
Pulse Compression Method for Radar Signal ProcessingEditor IJCATR
One fundamental issue in designing a good radar system is it’s capability to resolve two small targets that are located at
long range with very small separation between them. Pulse compression techniques are used in radar systems to avail the benefits
of large range detection capability of long duration pulse and high range resolution capability of short duration pulse. In these
techniques a long duration pulse is used which is frequency modulated before transmission and the received signal is passed through a
match filter to accumulate the energy into a short pulse. A matched filter is used for pulse compression to achieve high signal-to-noise
ratio (SNR). Two important factors to be considered for radar waveform design are range resolution and maximum range detection.
Range resolution is the ability of the radar to separate closely spaced targets and it is related to the pulse width of the waveform. The
narrower the pulse width the better is the range resolution. But, if the pulse width is decreased, the amount of energy in the pulse is
decreased and hence maximum range detection gets reduced. To overcome this problem pulse compression techniques are used in the
radar systems. In this paper, the pulse compression technique is described to resolve two small targets that are located at long
range with very small separation between them.
The proposed modulation technique employs
quadrature mixing to achieve transmission of high frequency
data over a narrow channel. In this modulation technique, the
phase of carrier is varied in accordance with the instantaneous
amplitude of the message signal. The message data bits are
transformed to an unintelligible form which then modulates a
carrier signal. The modulation technique induces probabilistic
characteristic over the entire process. The nondeterministic
nature of data is enhanced and thereby providing integrity and
confidentiality to the data which is transmitted across a channel.
Another important feature of this technique is that prediction of
the message data bits by observing the modulated signal is foiled
due to the use of different phase shifts for 40 symbols. In this
technique, the spectrum of modulated signal is translated to be
centered at 0 Hz. At the demodulator, the instantaneous
amplitude and phase can easily be determined. The major
advantage of this digital modulation technique is that, signaling
rate, requirement of high frequency carrier and transmission
channel bandwidth is reduced to a considerable extent without
compromising the transmission capacity and data rate.
This document discusses audio compression using multiple transformation techniques for audio applications. It compares the Discrete Cosine Transform (DCT) and Discrete Wavelet Transform (DWT) for compressing audio signals. The DCT and DWT are applied to audio signals to generate new data sets with smaller values, achieving compression. Performance is evaluated using metrics like compression ratio, peak signal-to-noise ratio, signal-to-noise ratio, and normalized root mean square error. The results show that DWT provides a lower compression ratio but higher performance metrics compared to DCT. Overall, the document examines using DCT and DWT transforms to compress audio signals and compares their performance.
The document discusses various types of guided transmission media used for data communication, including twisted pair cables, coaxial cables, and fiber optic cables. It explains that twisted pair cables are commonly used to connect devices within buildings and can support speeds up to 1 Gbps. Coaxial cables have better shielding and bandwidth than twisted pair and can transmit signals over longer distances. Fiber optic cables have the highest bandwidth capacity and can support speeds over 70 Gbps. The document also provides details on the construction and properties of coaxial cables.
Microwave Planar Sensor for Determination of the Permittivity of Dielectric M...journalBEEI
This paper proposed a single port rectangular microwave resonator sensor. This sensor operates at the resonance frequency of 4GHz. The sensor consists of micro-strip transmission line and applied the enhancement method. The enhancement method is able to improve the return loss of the sensor, respectively. Plus, the proposed sensor is designed and fabricated on Roger 5880 substrate. Based on the results, the percentage of error for the proposed rectangular sensor is 0.2% to 8%. The Q-factor of the sensor is 174.
This document provides an overview of physical layer fundamentals in networking. It discusses how the physical layer converts frames from the data link layer into electrical, optical, or electromagnetic signals for transmission. It describes analog communication principles like simple harmonic motion and how data is transmitted through amplitude, frequency, or phase modulation. The document also covers digital communication concepts such as representing data as discrete zeros and ones, and discusses bandwidth, bit rate, baud rate, throughput, and multiplexing techniques like time division multiplexing.
analog communication system for undergraduate .pdfAlaAwouda
This document provides an outline and introduction to the concepts of analog and digital communication systems. It discusses key topics such as modulation techniques, signal systems, bandwidth, and noise. Modulation techniques covered include amplitude modulation, frequency modulation, phase modulation, amplitude shift keying, frequency shift keying, and phase shift keying. It also discusses pulse code modulation, differential pulse code modulation, delta modulation, and adaptive delta modulation. Production of amplitude modulated signals using a block diagram approach is described.
International Journal of Engineering Research and Applications (IJERA) aims to cover the latest outstanding developments in the field of all Engineering Technologies & science.
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
Our journal system primarily aims to bring out the research talent and the works done by sciaentists, academia, engineers, practitioners, scholars, post graduate students of engineering and science. This journal aims to cover the scientific research in a broader sense and not publishing a niche area of research facilitating researchers from various verticals to publish their papers. It is also aimed to provide a platform for the researchers to publish in a shorter of time, enabling them to continue further All articles published are freely available to scientific researchers in the Government agencies,educators and the general public. We are taking serious efforts to promote our journal across the globe in various ways, we are sure that our journal will act as a scientific platform for all researchers to publish their works online.
Wavelet-based sensing technique in cognitive radio networkTELKOMNIKA JOURNAL
Cognitive radio is a smart radio that can change its transmitter parameter based on interaction with the environment in which it operates. The demand for frequency spectrum is growing due to a big data issue as many Internet of Things (IoT) devices are in the network. Based on previous research, most frequency spectrum was used, but some spectrums were not used, called spectrum hole. Energy detection is one of the spectrum sensing methods that has been frequently used since it is easy to use and does not require license users to have any prior signal understanding. But this technique is incapable of detecting at low signal-to-noise ratio (SNR) levels. Therefore, the wavelet-based sensing is proposed to overcome this issue and detect spectrum holes. The main objective of this work is to evaluate the performance of wavelet-based sensing and compare it with the energy detection technique. The findings show that the percentage of detection in wavelet-based sensing is 83% higher than energy detection performance. This result indicates that the wavelet-based sensing has higher precision in detection and the interference towards primary user can be decreased.
This document contains a summary of key concepts in digital communication. It discusses digital communication, quantizing, encoding, advantages and disadvantages of digital communication, basic signal processing operations, common channels used, telephone channel specifications, adaptive equalization, waveform coding techniques including pulse modulation, analog pulse modulation types, digital pulse modulation types like PCM and DM, sampling, quantizing, uniform and non-uniform quantization, companding, applications of PCM, advantages and disadvantages of delta modulation and DPCM, and an introduction to digital modulation techniques.
2.1 Theoretical Basis For Data Communication
What every sophomore EE knows !!! How much data can be put on a wire? What are the limits imposed by a medium?
2.2 Transmission Media
Wires and fibers.
2.3 Wireless Transmission
Radio, microwave, infrared, unguided by a medium.
2.4 The Telephone System
The system invented 100 years ago to carry voice.
2.5 Narrowband ISDN
Mechanisms that can carry voice and data.
This document provides answers to interview questions about computer networks. It begins by defining key concepts like data communication, simplex, half-duplex, and full-duplex transmission. It then discusses network topologies like star, bus, ring and mesh. Other topics covered include LAN, MAN, WAN definitions; TCP/IP and OSI models; network protocols; transmission media; error detection methods; switching; and wireless communication standards like Bluetooth. The document provides detailed explanations of computer network fundamentals.
This document discusses definitions and common misuses of four telecommunications terms: bandwidth, bit rate, symbol, and baud. It begins by defining bandwidth from several perspectives, including the commonly used 3dB power rule definition. It then discusses how information transmission capacity is measured in bits per second, and how modulation techniques like QPSK and 8-PSK can pack more bits per hertz of bandwidth. While bits per second and bauds are synonymous in binary modulation, they differ in higher-order modulation. Overall, the document seeks to resolve ambiguities around these terms and advocate for more precise usage.
This document discusses digital communication and TCP/IP networks. It begins by introducing digital communication and some of its advantages over analog transmission, such as better noise immunity and support for encryption. It then discusses topics like harmonic distortion, signal-to-noise ratio, and bandwidth capacity based on Shannon's theorem. The document focuses on analyzing signal distortions in both the time and frequency domains using MATLAB simulations. Finally, it describes the role of the TCP protocol in providing reliable data transmission over IP networks according to the OSI reference model.
This document provides an introduction to communication systems. It defines a communication system as a system that transfers information from one place to another. Communication systems have various components including a source that generates a message, a transmitter that converts the message to a signal, a channel that conveys the signal, a receiver that converts the signal back to a message, and a destination. Communication systems can transfer both analog and digital signals and messages. Key aspects of communication systems discussed include modulation, encoding, bandwidth, and the tradeoff between communication resources and system performance.
Improved performance of scs based spectrum sensing in cognitive radio using d...eSAT Journals
Abstract
Tremendous growth in current wireless networks raises the demand of more frequency spectrum, over the finite availability of spectrum resource. Although, the research has specifies that the available primary users (i.e. licensed user) has not occupying the channel all the time. The most effective technology known as Cognitive radio giving promises for a solution of under utilization of available frequency spectrum in wireless communication. In cognitive radio network two types of wireless user can be define as primary user and secondary user. Primary users have highest priority to utilize the available band of frequency and secondary user can utilize these services only when the channel is vacant by primary user and there will be no any interference. The optimization of this may be implemented by a smart technique such as cognitive radio, which is fully automated intelligent wireless sensor tool having capability to sense, learn & adjust relevant operating parameters dynamically in radio atmosphere. This can be happen if we prefer the appropriate window technique to evaluate system parameter for sensing the availability of vacant band. We show that by comparing the different windows techniques, cognitive radios not only provide better spectrum opportunity but also provide the chance to huge number of wireless users.
Keywords: Primary user, Secondary user, Spectrum Sensing and Window technique etc.
Similar to Data communication VTU SYLLABUS Based presentation (20)
Redefining brain tumor segmentation: a cutting-edge convolutional neural netw...IJECEIAES
Medical image analysis has witnessed significant advancements with deep learning techniques. In the domain of brain tumor segmentation, the ability to
precisely delineate tumor boundaries from magnetic resonance imaging (MRI)
scans holds profound implications for diagnosis. This study presents an ensemble convolutional neural network (CNN) with transfer learning, integrating
the state-of-the-art Deeplabv3+ architecture with the ResNet18 backbone. The
model is rigorously trained and evaluated, exhibiting remarkable performance
metrics, including an impressive global accuracy of 99.286%, a high-class accuracy of 82.191%, a mean intersection over union (IoU) of 79.900%, a weighted
IoU of 98.620%, and a Boundary F1 (BF) score of 83.303%. Notably, a detailed comparative analysis with existing methods showcases the superiority of
our proposed model. These findings underscore the model’s competence in precise brain tumor localization, underscoring its potential to revolutionize medical
image analysis and enhance healthcare outcomes. This research paves the way
for future exploration and optimization of advanced CNN models in medical
imaging, emphasizing addressing false positives and resource efficiency.
Electric vehicle and photovoltaic advanced roles in enhancing the financial p...IJECEIAES
Climate change's impact on the planet forced the United Nations and governments to promote green energies and electric transportation. The deployments of photovoltaic (PV) and electric vehicle (EV) systems gained stronger momentum due to their numerous advantages over fossil fuel types. The advantages go beyond sustainability to reach financial support and stability. The work in this paper introduces the hybrid system between PV and EV to support industrial and commercial plants. This paper covers the theoretical framework of the proposed hybrid system including the required equation to complete the cost analysis when PV and EV are present. In addition, the proposed design diagram which sets the priorities and requirements of the system is presented. The proposed approach allows setup to advance their power stability, especially during power outages. The presented information supports researchers and plant owners to complete the necessary analysis while promoting the deployment of clean energy. The result of a case study that represents a dairy milk farmer supports the theoretical works and highlights its advanced benefits to existing plants. The short return on investment of the proposed approach supports the paper's novelty approach for the sustainable electrical system. In addition, the proposed system allows for an isolated power setup without the need for a transmission line which enhances the safety of the electrical network
Understanding Inductive Bias in Machine LearningSUTEJAS
This presentation explores the concept of inductive bias in machine learning. It explains how algorithms come with built-in assumptions and preferences that guide the learning process. You'll learn about the different types of inductive bias and how they can impact the performance and generalizability of machine learning models.
The presentation also covers the positive and negative aspects of inductive bias, along with strategies for mitigating potential drawbacks. We'll explore examples of how bias manifests in algorithms like neural networks and decision trees.
By understanding inductive bias, you can gain valuable insights into how machine learning models work and make informed decisions when building and deploying them.
Using recycled concrete aggregates (RCA) for pavements is crucial to achieving sustainability. Implementing RCA for new pavement can minimize carbon footprint, conserve natural resources, reduce harmful emissions, and lower life cycle costs. Compared to natural aggregate (NA), RCA pavement has fewer comprehensive studies and sustainability assessments.
Comparative analysis between traditional aquaponics and reconstructed aquapon...bijceesjournal
The aquaponic system of planting is a method that does not require soil usage. It is a method that only needs water, fish, lava rocks (a substitute for soil), and plants. Aquaponic systems are sustainable and environmentally friendly. Its use not only helps to plant in small spaces but also helps reduce artificial chemical use and minimizes excess water use, as aquaponics consumes 90% less water than soil-based gardening. The study applied a descriptive and experimental design to assess and compare conventional and reconstructed aquaponic methods for reproducing tomatoes. The researchers created an observation checklist to determine the significant factors of the study. The study aims to determine the significant difference between traditional aquaponics and reconstructed aquaponics systems propagating tomatoes in terms of height, weight, girth, and number of fruits. The reconstructed aquaponics system’s higher growth yield results in a much more nourished crop than the traditional aquaponics system. It is superior in its number of fruits, height, weight, and girth measurement. Moreover, the reconstructed aquaponics system is proven to eliminate all the hindrances present in the traditional aquaponics system, which are overcrowding of fish, algae growth, pest problems, contaminated water, and dead fish.
Advanced control scheme of doubly fed induction generator for wind turbine us...IJECEIAES
This paper describes a speed control device for generating electrical energy on an electricity network based on the doubly fed induction generator (DFIG) used for wind power conversion systems. At first, a double-fed induction generator model was constructed. A control law is formulated to govern the flow of energy between the stator of a DFIG and the energy network using three types of controllers: proportional integral (PI), sliding mode controller (SMC) and second order sliding mode controller (SOSMC). Their different results in terms of power reference tracking, reaction to unexpected speed fluctuations, sensitivity to perturbations, and resilience against machine parameter alterations are compared. MATLAB/Simulink was used to conduct the simulations for the preceding study. Multiple simulations have shown very satisfying results, and the investigations demonstrate the efficacy and power-enhancing capabilities of the suggested control system.
KuberTENes Birthday Bash Guadalajara - K8sGPT first impressionsVictor Morales
K8sGPT is a tool that analyzes and diagnoses Kubernetes clusters. This presentation was used to share the requirements and dependencies to deploy K8sGPT in a local environment.
A SYSTEMATIC RISK ASSESSMENT APPROACH FOR SECURING THE SMART IRRIGATION SYSTEMSIJNSA Journal
The smart irrigation system represents an innovative approach to optimize water usage in agricultural and landscaping practices. The integration of cutting-edge technologies, including sensors, actuators, and data analysis, empowers this system to provide accurate monitoring and control of irrigation processes by leveraging real-time environmental conditions. The main objective of a smart irrigation system is to optimize water efficiency, minimize expenses, and foster the adoption of sustainable water management methods. This paper conducts a systematic risk assessment by exploring the key components/assets and their functionalities in the smart irrigation system. The crucial role of sensors in gathering data on soil moisture, weather patterns, and plant well-being is emphasized in this system. These sensors enable intelligent decision-making in irrigation scheduling and water distribution, leading to enhanced water efficiency and sustainable water management practices. Actuators enable automated control of irrigation devices, ensuring precise and targeted water delivery to plants. Additionally, the paper addresses the potential threat and vulnerabilities associated with smart irrigation systems. It discusses limitations of the system, such as power constraints and computational capabilities, and calculates the potential security risks. The paper suggests possible risk treatment methods for effective secure system operation. In conclusion, the paper emphasizes the significant benefits of implementing smart irrigation systems, including improved water conservation, increased crop yield, and reduced environmental impact. Additionally, based on the security analysis conducted, the paper recommends the implementation of countermeasures and security approaches to address vulnerabilities and ensure the integrity and reliability of the system. By incorporating these measures, smart irrigation technology can revolutionize water management practices in agriculture, promoting sustainability, resource efficiency, and safeguarding against potential security threats.
TIME DIVISION MULTIPLEXING TECHNIQUE FOR COMMUNICATION SYSTEMHODECEDSIET
Time Division Multiplexing (TDM) is a method of transmitting multiple signals over a single communication channel by dividing the signal into many segments, each having a very short duration of time. These time slots are then allocated to different data streams, allowing multiple signals to share the same transmission medium efficiently. TDM is widely used in telecommunications and data communication systems.
### How TDM Works
1. **Time Slots Allocation**: The core principle of TDM is to assign distinct time slots to each signal. During each time slot, the respective signal is transmitted, and then the process repeats cyclically. For example, if there are four signals to be transmitted, the TDM cycle will divide time into four slots, each assigned to one signal.
2. **Synchronization**: Synchronization is crucial in TDM systems to ensure that the signals are correctly aligned with their respective time slots. Both the transmitter and receiver must be synchronized to avoid any overlap or loss of data. This synchronization is typically maintained by a clock signal that ensures time slots are accurately aligned.
3. **Frame Structure**: TDM data is organized into frames, where each frame consists of a set of time slots. Each frame is repeated at regular intervals, ensuring continuous transmission of data streams. The frame structure helps in managing the data streams and maintaining the synchronization between the transmitter and receiver.
4. **Multiplexer and Demultiplexer**: At the transmitting end, a multiplexer combines multiple input signals into a single composite signal by assigning each signal to a specific time slot. At the receiving end, a demultiplexer separates the composite signal back into individual signals based on their respective time slots.
### Types of TDM
1. **Synchronous TDM**: In synchronous TDM, time slots are pre-assigned to each signal, regardless of whether the signal has data to transmit or not. This can lead to inefficiencies if some time slots remain empty due to the absence of data.
2. **Asynchronous TDM (or Statistical TDM)**: Asynchronous TDM addresses the inefficiencies of synchronous TDM by allocating time slots dynamically based on the presence of data. Time slots are assigned only when there is data to transmit, which optimizes the use of the communication channel.
### Applications of TDM
- **Telecommunications**: TDM is extensively used in telecommunication systems, such as in T1 and E1 lines, where multiple telephone calls are transmitted over a single line by assigning each call to a specific time slot.
- **Digital Audio and Video Broadcasting**: TDM is used in broadcasting systems to transmit multiple audio or video streams over a single channel, ensuring efficient use of bandwidth.
- **Computer Networks**: TDM is used in network protocols and systems to manage the transmission of data from multiple sources over a single network medium.
### Advantages of TDM
- **Efficient Use of Bandwidth**: TDM all
A review on techniques and modelling methodologies used for checking electrom...nooriasukmaningtyas
The proper function of the integrated circuit (IC) in an inhibiting electromagnetic environment has always been a serious concern throughout the decades of revolution in the world of electronics, from disjunct devices to today’s integrated circuit technology, where billions of transistors are combined on a single chip. The automotive industry and smart vehicles in particular, are confronting design issues such as being prone to electromagnetic interference (EMI). Electronic control devices calculate incorrect outputs because of EMI and sensors give misleading values which can prove fatal in case of automotives. In this paper, the authors have non exhaustively tried to review research work concerned with the investigation of EMI in ICs and prediction of this EMI using various modelling methodologies and measurement setups.
Generative AI leverages algorithms to create various forms of content
Data communication VTU SYLLABUS Based presentation
1. Data communication
Data exchange between two devices.
Attributes of data communication
Delivery
Accuracy
Timeliness
Jitter
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
2. Components of Communication System
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3. Data Representation
1) Text
2) Number
3) Image
4) Audio
5) Video
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4. Direction of Data Flow
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6. Physical Topology
The physical-topology defines how devices are
connected to make a network.
Four basic topologies are:
1) Mesh
2) Star
3) Bus
4) Ring
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
12. DATAAND SIGNALS
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Analog & Digital Data
Analog Data refers to information that is continuous.
Ex: human voice.
Digital Data refers to information that has discrete states.
Ex: 0s and 1s.
Dr. Mallikarjunaswamy N J, MITT, MYSORE
13. Analog & Digital Signals
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
14. Periodic & Non-Periodic Signals
Periodic Signal
Signals which repeat itself after a fixed time period are called Periodic
Signals.
Non-Periodic Signal
Signals which do not repeat itself after a fixed time period are called Non-
Periodic Signals.
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15. Transmission of Digital Signals
1) Baseband transmission.
2) Broadband transmission (using modulation).
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16. Baseband Transmission
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Baseband transmission means sending a digital
signal over a channel without changing the digital
signal to an analog signal.
Dr. Mallikarjunaswamy N J, MITT, MYSORE
17. Two cases of a baseband
communication:
Case 1: Low-pass channel with a wide bandwidth.
Case 2: Low-pass channel with a limited
bandwidth.
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
18. Bandwidth of two pass channel
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
19. Case 1: Low-pass channel with a
wide bandwidth19
Dr. Mallikarjunaswamy N J, MITT, MYSORE
20. Case 2: Low-Pass Channel with
Limited Bandwidth
In a low-pass channel with limited bandwidth, we
approximate the digital signal with an analog
signal.
Packet loss occours.
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
33. Decibel
The decibel (dB) measures the relative
strengths of
→ 2 signals or
→ one signal at 2 different points.
The decibel is negative if a signal is
attenuated. The decibel is positive if a signal is
amplified.
Variables P1 and P2 are the powers of a signal
at points 1 and 2, respectively.
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
36. Noise
Thermal Noise
Induced Noise
Crosstalk
Impulse Noise
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
37. Signal-to-Noise Ratio (SNR)
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•SNR is used to find the theoretical bit-rate limit.
•SNR is defined as
•SNR is actually the ratio of what is wanted (signal) to what is not wanted (noise).
•A high-SNR means the signal is less corrupted by noise.
A low-SNR means the signal is more corrupted by noise.
Because SNR is the ratio of 2 powers, it is often described in decibel units, SNRdB,
defined as
Dr. Mallikarjunaswamy N J, MITT, MYSORE
39. DATA RATE LIMITS
Data-rate depends on 3 factors:
Bandwidth available
Level of the signals
Quality of channel (the level of noise)
Two theoretical formulas can be used to calculate the data-rate:
Nyquist for a noiseless channel and
Shannon for a noisy channel.
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
40. Noiseless Channel: Nyquist Bit Rate
For a noiseless channel, the Nyquist bit-rate
formula defines the theoretical maximum bit-
rate
where bandwidth = bandwidth of the channel
L = number of signal-levels used to represent
data BitRate = bitrate of channel in bps
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
42. Noisy Channel: Shannon
Capacity
In reality, we cannot have a noiseless
channel; the channel is always noisy. For a
noisy channel, the Shannon capacity formula
defines the theoretical maximum bit-rate.
where bandwidth = bandwidth of channel in
bps.
SNR = signal-to-noise ratio.
Capacity = capacity of channel in bps.
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
44. PERFORMANCE
1) Bandwidth
2) Throughput
3) Latency (Delay)
Propagation Time
Transmission Time
Queuing Time
Processing Delay
4) Bandwidth Delay Product
5) Jitter
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
45. 1. Bandwidth
Bandwidth of an Analog Signal (in hz)
Bandwidth of a Digital Signal (in bps)
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
46. Bandwidth of an Analog
Signal (in hz)
Bandwidth of an analog signal is expressed in terms of its
frequencies.
Bandwidth is defined as the range of frequencies that the channel
can carry.
It is calculated by the difference b/w the maximum frequency and
the minimum frequency.
46
In figure 3.13, the signal has a minimum frequency of F1 = 1000Hz and maximum
frequency of F2 = 5000Hz.
Hence, the bandwidth is given by F2 - F1= 5000 - 1000 = 4000 Hz
Dr. Mallikarjunaswamy N J, MITT, MYSORE
47. Bandwidth of a Digital Signal (in bps)
Bandwidth refers to the number of bits transmitted in
one second in a channel (or link).
For example:
The bandwidth of a Fast Ethernet is a maximum of
100 Mbps. (This means that this network can send
100 Mbps).
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
48. Throughput
The throughput is a measure of how fast we can actually send data through
a network.
Although, bandwidth in bits per second and throughput seem the same,
they are actually different.
A link may have a bandwidth of B bps, but we can only send T bps
through this link with T always less than B.
In other words,
The bandwidth is a potential measurement of a link.
The throughput is an actual measurement of how fast we can send data.
For example:
¤ We may have a link with a bandwidth of 1 Mbps, but the devices
connected to the end of the link may handle only 200 kbps.
¤ This means that we cannot send more than 200 kbps through this link.
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
49. Latency (Delay)
The latency defines how long it takes for an
entire message to completely arrive at the
destination from the time the first bit is sent out
from the source.
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
50. Propagation Time
Propagation time is defined as the time
required for a bit to travel from source to
destination.
Propagation time is given by
50
Propagation speed of electromagnetic signals depends on
→ medium and
→ frequency of the signal.
Dr. Mallikarjunaswamy N J, MITT, MYSORE
51. Transmission Time
The time required for transmission of a
message depends on
→ size of the message and
→ bandwidth of the channel.
The transmission time is given by
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
52. Queuing Time
Queuing-time is the time needed for each intermediate-device to hold
the message before it can be processed.
(Intermediate device may be a router or a switch)
The queuing-time is not a fixed factor. This is because
Queuing-time changes with the load imposed on the network.
When there is heavy traffic on the network, the queuing-time increases.
An intermediate-device
→ queues the arrived messages and
→ processes the messages one by one.
If there are many messages, each message will have to wait.
52
Dr. Mallikarjunaswamy N J, MITT, MYSORE
53. Processing Delay
Processing delay is the time taken by the
routers to process the packet header.
53
Dr. Mallikarjunaswamy N J, MITT, MYSORE
54. Bandwidth Delay Product
Two performance-metrics of a link are 1)
Bandwidth and 2) Delay
The bandwidth-delay product is very important
in data-communications.
Let us elaborate on this issue, using 2
hypothetical cases as examples.
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
55. Jitter
Another performance issue that is related to delay is jitter.
We can say that jitter is a problem
→ if different packets of data encounter different delays
and
→ if the application using the data at the receiver site is
time-sensitive (for ex: audio/video).
For example:
If the delay for the first packet is 20 ms the delay for the
second is 45 ms and the delay for the third is 40 ms
then the real-time application that uses the packets suffers
from jitter.
55
Dr. Mallikarjunaswamy N J, MITT, MYSORE
56. MODULE 2- DIGITAL TRANSMISSION
ANALOG TO DIGITAL CONVERSION
PCM
Sampling
Quantization &
Encoding.
56
Dr. Mallikarjunaswamy N J, MITT, MYSORE
57. Analog to Digital conversion
57
Dr. Mallikarjunaswamy N J, MITT, MYSORE
58. 1. Sampling
We convert the continuous time signal (analog) into the
discrete time signal (digital).
Pulses from the analog-signal are sampled every Ts sec
where Ts is the sample-interval or period.
The inverse of the sampling-interval is called the sampling-
frequency (or sampling-rate).
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
59. Type of sampling
Three sampling methods
Ideal Sampling
An impulse at each sampling instant.
Natural Sampling
A high-speed switch is turned ON for only the small period of time when the sampling occurs. The
result is a sequence of samples that retains the shape of the analog-signal.
Flat Top Sampling
The most common sampling method is sample and hold. Sample and hold method creates flat-top
samples. This method is sometimes referred to as PAM (pulse amplitude modulation).
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
60. Sampling Rate
According to Nyquist theorem,
“The sampling-rate must be at least 2
times the highest frequency, not the
bandwidth“.
If the analog-signal is low-pass, the bandwidth and the
highest frequency are the same value.
If the analog-signal is bandpass, the bandwidth value is
lower than the value of the maximum frequency.
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
61. 2. Quantization
61
•The sampled-signal is quantized.
•Result of sampling is a set of pulses with amplitude-values b/w max & min amplitudes of the signal.
•Four steps in quantization:
1.We assume that the original analog-signal has amplitudes between Vmin & Vmax.
2.We divide the range into L zones, each of height Δ(delta).
3. We assign quantized values of 0 to (L-1) to the midpoint of each zone.
4. We approximate the value of the sample amplitude to the quantized values.
For example: Let Vmin=-20 Vmax =+20 V L = 8
Therefore, Δ = [+20-(-20)]/8= 5 V
Dr. Mallikarjunaswamy N J, MITT, MYSORE
63. 3. Encoding
The quantized values are encoded as n-bit code word.
In the previous example,
A quantized value 2 is encoded as 010. A quantized value 5
is encoded as 101.
Relationship between number of quantization-levels (L) &
number of bits (n) is given by n=log2L or 2n=L
The bit-rate is given by:
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
64. Original Signal Recovery
PCM decoder is used for recovery of the original signal.
Here is how it works :
The decoder first uses circuitry to convert the code words into a pulse that holds the
amplitude until the next pulse.
Next, the staircase-signal is passed through a low-pass filter to smooth the staircase
signal into an analog-signal.
The filter has the same cut-off frequency as the original signal at the sender.
If the signal is sampled at the Nyquist sampling-rate, then the original signal will be re-created.
The maximum and minimum values of the original signal can be achieved by using amplification.
64
Dr. Mallikarjunaswamy N J, MITT, MYSORE
65. TRANSMISSION MODES
65
PARALLEL TRANSMISSION
Multiple bits are sent with each clock-tick .
„n‟ bits in a group are sent simultaneously.
„n‟ wires are used to send „n‟ bits at one time.
Each bit has its own wire.
Typically, the 8 wires are bundled in a cable with a connector at each end.
Dr. Mallikarjunaswamy N J, MITT, MYSORE
67. Synchronous Transmission
One bit is sent with each clock-tick using only
a single link.
1. synchronous Transmission
67
Dr. Mallikarjunaswamy N J, MITT, MYSORE
68. 2. Asynchronous
68
Asynchronous transmission is so named because the timing of a signal is not important (Figure 4.34).
Prior to data transfer, both sender & receiver agree on pattern of information to be exchanged.
Normally, patterns are based on grouping the bit-stream into bytes.
The sender transmits each group to the link without regard to a timer.
As long as those patterns are followed, the receiver can retrieve the info. without regard to a timer.
There may be a gap between bytes.
We send
→ 1 start bit (0) at the beginning of each byte
→1 stop bit (1) at the end of each byte.
Start bit alerts the receiver to the arrival of a new group. Stop bit lets the receiver know that the byte is finished.
Here, the term asynchronous means “asynchronous at the byte level”. However, the bits are still synchronized & bit-
durations are the same.
Dr. Mallikarjunaswamy N J, MITT, MYSORE
69. DIGITAL TO ANALOG
CONVERSION69
Digital-to-analog conversion is the process of changing one of the
characteristics of an analog-signal based on the information in digital-data.
Dr. Mallikarjunaswamy N J, MITT, MYSORE
70. Four methods of digital to
analog conversion
1) Amplitude shift keying (ASK)
2) Frequency shift keying (FSK)
3) Phase shift keying (PSK)
4) Quadrature amplitude modulation (QAM).
70
Dr. Mallikarjunaswamy N J, MITT, MYSORE
71. Digital to analog conversion
Dr. Mallikarjunaswamy N J, MITT, MYSORE
71
72. 1) Amplitude shift keying (ASK)
•The amplitude of the carrier-signal is varied to represent
different signal-elements.
• Both frequency and phase remain constant for all signal-
elements.
1. Binary ASK (BASK)
• BASK is implemented using only 2 levels.
• This is also referred to as OOK (On-Off Keying).
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
73. Implementation of BASK
Here, line coding method used = unipolar NRZ (Figure 5.4).
• The unipolar NRZ signal is multiplied by the carrier-frequency coming
from an oscillator.
1) When amplitude of the NRZ signal = 0, amplitude of the carrier-signal =
0.
2) When amplitude of the NRZ signal = 1, the amplitude of the carrier-
signal is held.
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
74. Frequency Shift Keying (FSK)
• The frequency of the carrier-signal is varied to
represent different signal-elements.
• The frequency of the modulated-signal is constant for
the duration of one signal-element, but changes for the
next signal-element if the data-element changes.
• Both amplitude and phase remain constant for all
signal-elements.
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
76. Phase Shift Keying (PSK)
• The phase of the carrier-signal is varied to represent different
signal-elements.
• Both amplitude and frequency remain constant for all signal-
elements.
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
78. Quadrature PSK (QPSK)
• The scheme is called QPSK because it uses 2 separate BPSK
modulations.
1) First modulation is in-phase,
2) Second modulation is quadrature (out-of-phase).
• A serial-to-parallel converter
→ accepts the incoming bits
→ sends first bit to first modulator and
→ sends second bit to second modulator.
• The bit to each BPSK signal has one-half the frequency of the
original signal.
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Dr. Mallikarjunaswamy N J, MITT, MYSORE
82. Frequency Division
Multiplexing (FDM)
Dr. Mallikarjunaswamy N J, MITT, MYSORE
82
• FDM is an analog multiplexing technique that combines analog signals
(Figure 6.3).
• FDM can be used when the bandwidth of a link is greater than the
combined bandwidths of the
signals to be transmitted. (Bandwidth measured in hertz).
86. Wavelength Division
Multiplexing (WDM)86
• WDM is an analog multiplexing technique that combines analog signals.
• WDM is designed to use the high-data-rate capability of fiber optical-cable.
• The data-rate of optical-cable is higher than the data-rate of metallic-cable.
• Using an optical-cable for one single line wastes the available bandwidth.
• Multiplexing allows combining several lines into one line.
Dr. Mallikarjunaswamy N J, MITT, MYSORE
87. Wavelength division MUX and
DEMUX87
A multiplexer combines several narrow-bands of light into a wider-band of
light.
A demultiplexer divides a wider-band of light into several narrow-bands of
light.
A prism is used for combining and splitting of light sources.
A prism bends a beam of light based on
→ angle of incidence and
→ frequency.
Dr. Mallikarjunaswamy N J, MITT, MYSORE
88. Time Division Multiplexing
(TDM)88
• TDM is a digital multiplexing technique that combines digital signals.
• TDM combines several low-rate channels into one high-rate one.
• Each connection occupies a portion of time in the link.
• Several connections share the high bandwidth of a line.
Dr. Mallikarjunaswamy N J, MITT, MYSORE
89. SPREAD SPECTRUM
89
• Spread-spectrum is used in wireless applications (Figure 6.27).
• In wireless applications, all stations use air (or a vacuum) as the medium for
communication.
• If the required bandwidth for each station is B, spread-spectrum expands it to Bss
such that Bss>>B.
• The expanded-bandwidth allows the source to place its message in a protective
envelope for a more
secure transmission.
Dr. Mallikarjunaswamy N J, MITT, MYSORE
90. Two types of spread-spectrum:
90
1) Frequency hopping spread-spectrum (FHSS) and
2) Direct sequence spread-spectrum (DSSS).
Dr. Mallikarjunaswamy N J, MITT, MYSORE
92. Direct Sequence Spread
Spectrum (DSSS)92
• This technique expands the bandwidth of the original signal.
• Each data-bit is replaced with „n‟ bits using a spreading-code.
• Each bit is assigned a code of „n‟ bits called chips.
• The chip-rate is „n‟ times that of the data-bit (Figure 6.32).
Dr. Mallikarjunaswamy N J, MITT, MYSORE
93. SWITCHING
93
• A network is a set of connected-devices.
• Problem: Whenever we have multiple-devices, we have the problem of
how to connect them to make
one-to-one communication possible.
• Solution: Use Switching.
• A switched-network consists of a series of interlinked-nodes, called
switches.
• Switches are devices capable of creating temporary connections between
two or more devices.
• In a switched-network,
1) Some nodes are connected to the end-systems
2) Some nodes are used only for routing.
Dr. Mallikarjunaswamy N J, MITT, MYSORE
94. Three Methods of Switching
94
Dr. Mallikarjunaswamy N J, MITT, MYSORE
95. CIRCUIT SWITCHED
NETWORK95
• This is similar to telephone system.
• Fixed path (connection) is established between a source and a destination
prior to the transfer of packets.
• A circuit-switched-network consists of a set of switches connected by
physical-links (Figure 8.3).
• A connection between 2 stations is a dedicated-path made of one or more
links.
• However, each connection uses only one dedicated-channel on each link.
• Normally, each link is divided into „n‟ channels by using FDM or TDM.
• The resources need to be reserved during the setup phase.
The resources remain dedicated for the entire duration of data transfer until the
teardown phase.
Dr. Mallikarjunaswamy N J, MITT, MYSORE
96. Circuit Switched Network
96
2.7.1 Three Phases
• The communication requires 3 phases:
1) Connection-setup
2) Data-transfer
3) Connection teardown.
Dr. Mallikarjunaswamy N J, MITT, MYSORE
97. Delay in a circuit switched N/W
97
Dr. Mallikarjunaswamy N J, MITT, MYSORE
98. PACKET SWITCHED
NETWORK98
Datagram Networks
• This is analogous to postal system.
• Each packet is routed independently through the network.
• Each packet has a header that contains source and destination addresses.
• Each switch examines the header to determine the next hop in the path to
the destination.
• If the transmission line is busy then the packet is placed in the queue until
the line becomes free.
• Packets are referred to as datagrams.
Dr. Mallikarjunaswamy N J, MITT, MYSORE
100. Virtual Circuit Network (VCN)
100
• This is similar to telephone system.
• A virtual-circuit network is a combination of circuit-switched-network and datagram-
network.
• Five characteristics of VCN:
1) As in a circuit-switched-network, there are setup & teardown phases in addition to the
data
transfer phase.
2) As in a circuit-switched-network, resources can be allocated during the setup phase.
As in a datagram-network, resources can also be allocated on-demand.
3) As in a datagram-network, data is divided into packets.
Each packet carries an address in the header.
However, the address in the header has local jurisdiction, not end-to-end jurisdiction.
4) As in a circuit-switched-network, all packets follow the same path established during the
connection.
5) A virtual-circuit network is implemented in the data link layer.
A circuit-switched-network is implemented in the physical layer.
A datagram-network is implemented in the network layer.
Dr. Mallikarjunaswamy N J, MITT, MYSORE
103. 3.1.1 Redundancy
103
• The central concept in detecting/correcting errors is redundancy.
• Some extra-bits along with the data have to be sent to detect/correct errors. These
extra bits are called
redundant-bits.
• The redundant-bits are
→ added by the sender and
→ removed by the receiver.
• The presence of redundant-bits allows the receiver to detect/correct errors.
Dr. Mallikarjunaswamy N J, MITT, MYSORE
104. 3.1.2 Coding
104
Redundancy is achieved through various coding-schemes.
1) Sender adds redundant-bits to the data-bits. This process creates a relationship
between
→ redundant-bits and
→ data-bits.
2) Receiver checks the relationship between redundant-bits & data-bits to detect/correct
errors.
• Two important factors to be considered:
1) Ratio of redundant-bits to the data-bits and
2) Robustness of the process.
• Two broad categories of coding schemes: 1) Block-coding and 2) Convolution coding.
Dr. Mallikarjunaswamy N J, MITT, MYSORE
105. 3.2 Block Coding
105
• The message is divided into k-bit blocks. These blocks are called data-words.
• Here, r-redundant-bits are added to each block to make the length n=k+r.
• The resulting n-bit blocks are called code-words.
• Since n>k, the number of possible code-words is larger than the number of
possible data-words.
• Block-coding process is 1-to-1; the same data-word is always encoded as the
same code-word.
• Thus, we have 2n-2k code-words that are not used. These code-words are
invalid or illegal.
Dr. Mallikarjunaswamy N J, MITT, MYSORE
106. 3.2.1 Error Detection
106
Here is how it works (Figure 10.2):
1) At Sender
i) The sender creates code-words out of data-words by using a generator.
The generator applies the rules and procedures of encoding.
ii) During transmission, each code-word sent to the receiver may change.
2) At Receiver
i) a) If the received code-word is the same as one of the valid code-words, the code-word is
accepted; the corresponding data-word is extracted for use.
b) If the received code-word is invalid, the code-word is discarded.
ii) However, if the code-word is corrupted but the received code-word still matches a valid
codeword, the error remains undetected.
• An error-detecting code can detect only the types of errors for which it is designed; other
types of errors may remain undetected.
Dr. Mallikarjunaswamy N J, MITT, MYSORE
108. 3.3 Cyclic Codes
108
Cyclic codes are special linear block codes with one extra property:
If a code-word is cyclically shifted (rotated), the result is another code-word.
For ex: if code-word = 1011000 and we cyclically left-shift, then another code-
word = 0110001.
• Let First-word = a0 to a6 and Second-word = b0 to b6, we can shift the bits by
using the following:
Dr. Mallikarjunaswamy N J, MITT, MYSORE
110. Cont ..
110
• Let Size of data-word = k bits (here k=4).
Size of code-word = n bits (here n=7).
Size of divisor = n-k+1 bits (here n-k+1=4). (Augmented increased)
• Here is how it works (Figure 10.5):
1) At Sender
n-k 0s is appended to the data-word to create augmented data-word. (here n-k=3).
The augmented data-word is fed into the generator (Figure 10.6).
The generator divides the augmented data-word by the divisor.
The remainder is called check-bits (r2r1r0).
The check-bits (r2r1r0) are appended to the data-word to create the code-word.
2) At Receiver
The possibly corrupted code-word is fed into the checker.
The checker is a replica of the generator.
The checker divides the code-word by the divisor.
The remainder is called syndrome bits (r2r1r0).
The syndrome bits are fed to the decision-logic-analyzer.
The decision-logic-analyzer performs following functions:
i) For No Error
¤ If all syndrome-bits are 0s, the received code-word is accepted.
¤ Data-word is extracted from received code-word (Figure 10.7a).
ii) For Error
¤ If all syndrome-bits are not 0s, the received code-word is discarded (Figure 10.7b).Dr. Mallikarjunaswamy N J, MITT, MYSORE
114. Cyclic Code Encoder Using
Polynomials114
• Let Data-word = 1001 = x3+1.
Divisor = 1011 = x3+x+1.
• In polynomial representation, the divisor is referred to as generator polynomial t(x)
(Figure 10.9).
Dr. Mallikarjunaswamy N J, MITT, MYSORE
116. 3.4 Checksum
116 Here is how it works (Figure 10.15):
1) At Source
Firstly the message is divided into m-bit units.
Then, the generator creates an extra m-bit unit called the checksum.
The checksum is sent with the message.
2) At Destination
The checker creates a new checksum from the combination of the message and
sentchecksum.
i) If the new checksum is all 0s, the message is accepted.
ii) If the new checksum is not all 0s, the message is discarded.
Dr. Mallikarjunaswamy N J, MITT, MYSORE
121. Here is how it works :
121
1) At Sender
The sender initializes the checksum to 0 and adds all data items and the checksum.
The result is 36.
However, 36 cannot be expressed in 4 bits.
The extra two bits are wrapped and added with the sum to create the wrapped sum value 6.
The sum is then complemented, resulting in the checksum value 9 (15 - 6 = 9).
The sender now sends six data items to the receiver including the checksum 9.
2) At Receiver
The receiver follows the same procedure as the sender.
It adds all data items (including the checksum); the result is 45.
The sum is wrapped and becomes 15. The wrapped sum is complemented and becomes 0.
Since the value of the checksum is 0, this means that the data is not corrupted.
The receiver drops the checksum and keeps the other data items.
If the checksum is not zero, the entire packet is dropped.
Dr. Mallikarjunaswamy N J, MITT, MYSORE