DSL technology provides high bit rate digital services over the existing telephone lines without the need for modifications to the customers facilities. Since the first field test of DSL technology, it has been recognized that Impulse Noise along with other impairments like attenuation and crosstalk, can affect the achievable bit rate of DSL systems. [1]
The purpose of this assignment is to analyze and simulate the impact of impulse noise on a DSL signal and the Impulse Noise protection's impact on the achievable Bit-rate. How ISPs use different "DSL profiles" on a customer's line to achieve better data-rates and synchronization stability will also be presented. A theoretical approach of the subject will be studied along with a practical one with the use of Matlab and the internal DSLAM Monitoring tool that a greek ISP company uses. Different "DSL profiles" will be tested on a customer's line to extract conclusions.
Visible light communication is a high-speed developing technique with LEDs for both lighting and data communication. In this paper, examined the visible light communication performance over Mach Zehnder Modulation via Optisystem simulation tool. Quality factor and BER values of different link distance are predicted by optisystem simulation tool. The planned system can support 5 Gbps data rate up to 50 meter of link distance with a Quality factor of 15.71 for without any external noise interruption. In the case of external noise influence, the planned VLC system performance is also investigated through simulation tool. Consider the external noise interruption, the designed system can support 2Gbps data rate up to 20-meter link distance of Quality factor of 11.935. Quality factor for the system without any external noise influence is better compared to the system with external noise influence.
Transmitting audio via fiber optics under nonlinear effects and optimized tun...IJECEIAES
The ability of fiber optic to overcome the signal transmission problems is making it a dominant transmission medium. Despite of this major positive attribute of optic fibers, there is still a downside for using the fiber optic communication; that is the nonlinearity problem. For the first time, a design of an audio signal is suggested and executed in MATLAB with integration with OptiSystem TM Software .The audio signal then transmitted in different shapes of modulation signals (NRZ, RZ, & RC) for different distances (100 km & 75 km) via a fiber optic media to be received in a receiving part of the simulated system. Three tests are used to do so. The first is the Quality-facto (Q-Factor) against the received power, second test is eye diagram performance and finally is the measuring of the amplitude of output (received) signal for each modulation signal shape using the Oscilloscope Visualizer. The NZR modulation signal was found to be the best one of the three used signals’ types in all three tests. The Q-factor for NRZ pulse shape (=12) was higher than that for RZ (=10) and RC (=8) for a 100 km distance at the same received power level.
Performance and interference analysis of 802.11 g wireless networkijwmn
This paper mainly presents Access Point s’ (APs’) p
erformance and co-channel, adjacent channel
interference according to 802.11g standard. Firstly
, our study illustrates the performance of one AP,
including its coverage performance, load-carrying p
roperties and fairness. Next we propose the details
about co-channel, adjacent channel interference whi
ch should be paid attention to in deploying network
services. Then, performance analyses are evaluated
by simulation and real test for a dense wireless
network. Our contribution is that the co-channel, a
djacent channel interference analysis, the simulati
on
and test results can be the basis offered to networ
k operators
Performance Improvement for Hybrid L-band Remote Erbium Doped Fiber Amplifier...IJECEIAES
We have demonstrated the performance improvement of L-band hybrid remote Erbium-doped fiber amplifier by introducing a phase modulator to suppress the stimulated Brilloiun scattering (SBS) effect in the transmission. The transmission gain has improved by 12.65dB while the noise figure has reduced by 47.1dB when 0dBm signal power is generated at 1590.05nm wavelength. Furthermore, the optical signal-to-noise ratio has improved from 7.81dB to 29.72dB when the signal power is varied from -30dBm to 0dBm. By implementing a phase modulator to the input signal somehow able to produce better performance regarding gain, noise figure and optical signalto-noise ratio, especially at the higher signal power as the gain, has been transferred to the Stokes signal and the amplified signal.
Visible light communication is a high-speed developing technique with LEDs for both lighting and data communication. In this paper, examined the visible light communication performance over Mach Zehnder Modulation via Optisystem simulation tool. Quality factor and BER values of different link distance are predicted by optisystem simulation tool. The planned system can support 5 Gbps data rate up to 50 meter of link distance with a Quality factor of 15.71 for without any external noise interruption. In the case of external noise influence, the planned VLC system performance is also investigated through simulation tool. Consider the external noise interruption, the designed system can support 2Gbps data rate up to 20-meter link distance of Quality factor of 11.935. Quality factor for the system without any external noise influence is better compared to the system with external noise influence.
Transmitting audio via fiber optics under nonlinear effects and optimized tun...IJECEIAES
The ability of fiber optic to overcome the signal transmission problems is making it a dominant transmission medium. Despite of this major positive attribute of optic fibers, there is still a downside for using the fiber optic communication; that is the nonlinearity problem. For the first time, a design of an audio signal is suggested and executed in MATLAB with integration with OptiSystem TM Software .The audio signal then transmitted in different shapes of modulation signals (NRZ, RZ, & RC) for different distances (100 km & 75 km) via a fiber optic media to be received in a receiving part of the simulated system. Three tests are used to do so. The first is the Quality-facto (Q-Factor) against the received power, second test is eye diagram performance and finally is the measuring of the amplitude of output (received) signal for each modulation signal shape using the Oscilloscope Visualizer. The NZR modulation signal was found to be the best one of the three used signals’ types in all three tests. The Q-factor for NRZ pulse shape (=12) was higher than that for RZ (=10) and RC (=8) for a 100 km distance at the same received power level.
Performance and interference analysis of 802.11 g wireless networkijwmn
This paper mainly presents Access Point s’ (APs’) p
erformance and co-channel, adjacent channel
interference according to 802.11g standard. Firstly
, our study illustrates the performance of one AP,
including its coverage performance, load-carrying p
roperties and fairness. Next we propose the details
about co-channel, adjacent channel interference whi
ch should be paid attention to in deploying network
services. Then, performance analyses are evaluated
by simulation and real test for a dense wireless
network. Our contribution is that the co-channel, a
djacent channel interference analysis, the simulati
on
and test results can be the basis offered to networ
k operators
Performance Improvement for Hybrid L-band Remote Erbium Doped Fiber Amplifier...IJECEIAES
We have demonstrated the performance improvement of L-band hybrid remote Erbium-doped fiber amplifier by introducing a phase modulator to suppress the stimulated Brilloiun scattering (SBS) effect in the transmission. The transmission gain has improved by 12.65dB while the noise figure has reduced by 47.1dB when 0dBm signal power is generated at 1590.05nm wavelength. Furthermore, the optical signal-to-noise ratio has improved from 7.81dB to 29.72dB when the signal power is varied from -30dBm to 0dBm. By implementing a phase modulator to the input signal somehow able to produce better performance regarding gain, noise figure and optical signalto-noise ratio, especially at the higher signal power as the gain, has been transferred to the Stokes signal and the amplified signal.
Raman amplifier performance in pre-amplifier use for optical fiber communicat...TELKOMNIKA JOURNAL
The development of telecommunications networks is currently dominated by fiber optics. The fiber optic has become a waveguide medium transmitting information with high frequency bands, high capacity and high speed. An optical amplifier is required to maintain electromagnetic signals when they propagate in far distance. One of the amplifiers, Fiber Raman Amplifiers (FRA) which is the light scattering from the light that comes with the phonon in the lattice of amplification medium produces photons that are coherent with the incoming photons. Many amplifiers are commonly used but the problems not only come from the amplifier but also the component circuit and system. By simulation method, FRA circuit is designed and operated in the form of pre-amplifiers to maintain a better signal from material interference and geometry. The simulation results show that the lowest BER value and the highest Q-factor are found at a distance of 10 km depicted by eye diagram.
5 Simulation of Gain flattening 32 channels EDFA-DWDM Optical SystemINFOGAIN PUBLICATION
The gain flatness of EDFA plays a very critical role in DWDM system applications in all optical network design. The main purpose of this paper is to achieve gain flatness for 32 channels in order to equalize amplitude gain of DWDM system. This system is simulated using Opti system software to achieve gain flatness of EDFA through variation of EDFA pump power and input power of system. The gains are flattened within 41±0.9 dB from Wavelength range 1546 to 1560 nm having noise figure less than 8dB, Optimized EDFA fiber length of 6.245 m and frequency spacing between channels is 0.4 nm simultaneously amplified in a EDFA of single stage. The working model consists of WDM transmitter , MUX, Pump laser, dual port WDM analyzer and EDFA as key components
International Journal of Engineering Research and Development (IJERD)IJERD Editor
International Journal of Engineering Research and Development is an international premier peer reviewed open access engineering and technology journal promoting the discovery, innovation, advancement and dissemination of basic and transitional knowledge in engineering, technology and related disciplines.
Ber performance of ofdm with discrete wavelet transform for time dispersive c...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
Low Noise Amplifier using Darlington Pair At 90nm Technology IJECEIAES
The demand of low noise amplifier (LNA) has been rising in today’s communication system. LNA is the basic building circuit of the receiver section satellite. The design concept demonstrates the design trade off with NF, gain, power consumption. This paper reports on with analysis of wideband LNA. This paper shows the schematic of LNA by using Darlington pair amplifier. This LNA has been fabricated on 90nm CMOS process. This paper is focused on to make comparison of three stage and single stage LNA. Here, the phase mismatch between these patameters is quantitavely analyzed to study the effect on gain and noise figure (NF). In this paper, single stage LNA has shown the 23 dB measured gain, while the three stages LNA has demonstrated 29 dB measured gain. Here, LNA designed using darlington pair shows low NF of 3.3-4.8 dB, which comparable to other reported single stage LNA designs and appreciably low compared to the three stages LNA. Hence, findings from this paper suggest the use of single stage LNA designed using Darlington pair in transceiver satellite applications.
Cisco DWDM Chromatic Dispertion Calculation in CTP\XLSValery Kayukov
Cisco DWDM Chromatic Dispertion Calculation in CTP\XLS:
- Princiopals of CD
- Measurement of CD
- Manual calculation in XLS
- Automatic Calculation in CTP
Spectrum sensing is an essential concept in cognitive radio. It exploits the inefficient utilization
of radio frequency spectrum without causing destructive interference to the licensed users. In
this paper we considered spectrum sensing of Digital Video Broadcast Terrestrial (DVB-T)
signal in different scenario. We compared various spectrum sensing algorithms that make use of
the second order statistics; the energy detector was also included for comparison. The results
show that it is possible to obtain good detection performance by exploiting the correlation
method.
Noise Immune Convolutional Encoder Design and Its Implementation in Tanner ijcisjournal
With the rapid advances in integrated circuit(IC) technologies, number of functions on a chip was
increasing at a very fast rate, with which interconnect density is increasing especially in functional logic
chips. The on-chip noise affects are increasing and needs to be addressed. In this paper we have
implemented a convolution encoder using a technique that provides higher noise immunity. The encoder
circuit is simulated in Tanner 15.0 with data rate of 25Mbps and a clock frequency of 250MHz
NOISE IMMUNE CONVOLUTIONAL ENCODER DESIGN AND ITS IMPLEMENTATIONIN TANNERIJCI JOURNAL
With the rapid advances in integrated circuit(IC) technologies, number of functions on a chip was increasing at a very fast rate, with which interconnect density is increasing especially in functional logic chips. The on-chip noise affects are increasing and needs to be addressed. In this paper we have implemented a convolution encoder using a technique that provides higher noise immunity. The encoder circuit is simulated in Tanner 15.0 with data rate of 25Mbps and a clock frequency of 250MHz
Raman amplifier performance in pre-amplifier use for optical fiber communicat...TELKOMNIKA JOURNAL
The development of telecommunications networks is currently dominated by fiber optics. The fiber optic has become a waveguide medium transmitting information with high frequency bands, high capacity and high speed. An optical amplifier is required to maintain electromagnetic signals when they propagate in far distance. One of the amplifiers, Fiber Raman Amplifiers (FRA) which is the light scattering from the light that comes with the phonon in the lattice of amplification medium produces photons that are coherent with the incoming photons. Many amplifiers are commonly used but the problems not only come from the amplifier but also the component circuit and system. By simulation method, FRA circuit is designed and operated in the form of pre-amplifiers to maintain a better signal from material interference and geometry. The simulation results show that the lowest BER value and the highest Q-factor are found at a distance of 10 km depicted by eye diagram.
5 Simulation of Gain flattening 32 channels EDFA-DWDM Optical SystemINFOGAIN PUBLICATION
The gain flatness of EDFA plays a very critical role in DWDM system applications in all optical network design. The main purpose of this paper is to achieve gain flatness for 32 channels in order to equalize amplitude gain of DWDM system. This system is simulated using Opti system software to achieve gain flatness of EDFA through variation of EDFA pump power and input power of system. The gains are flattened within 41±0.9 dB from Wavelength range 1546 to 1560 nm having noise figure less than 8dB, Optimized EDFA fiber length of 6.245 m and frequency spacing between channels is 0.4 nm simultaneously amplified in a EDFA of single stage. The working model consists of WDM transmitter , MUX, Pump laser, dual port WDM analyzer and EDFA as key components
International Journal of Engineering Research and Development (IJERD)IJERD Editor
International Journal of Engineering Research and Development is an international premier peer reviewed open access engineering and technology journal promoting the discovery, innovation, advancement and dissemination of basic and transitional knowledge in engineering, technology and related disciplines.
Ber performance of ofdm with discrete wavelet transform for time dispersive c...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
Low Noise Amplifier using Darlington Pair At 90nm Technology IJECEIAES
The demand of low noise amplifier (LNA) has been rising in today’s communication system. LNA is the basic building circuit of the receiver section satellite. The design concept demonstrates the design trade off with NF, gain, power consumption. This paper reports on with analysis of wideband LNA. This paper shows the schematic of LNA by using Darlington pair amplifier. This LNA has been fabricated on 90nm CMOS process. This paper is focused on to make comparison of three stage and single stage LNA. Here, the phase mismatch between these patameters is quantitavely analyzed to study the effect on gain and noise figure (NF). In this paper, single stage LNA has shown the 23 dB measured gain, while the three stages LNA has demonstrated 29 dB measured gain. Here, LNA designed using darlington pair shows low NF of 3.3-4.8 dB, which comparable to other reported single stage LNA designs and appreciably low compared to the three stages LNA. Hence, findings from this paper suggest the use of single stage LNA designed using Darlington pair in transceiver satellite applications.
Cisco DWDM Chromatic Dispertion Calculation in CTP\XLSValery Kayukov
Cisco DWDM Chromatic Dispertion Calculation in CTP\XLS:
- Princiopals of CD
- Measurement of CD
- Manual calculation in XLS
- Automatic Calculation in CTP
Spectrum sensing is an essential concept in cognitive radio. It exploits the inefficient utilization
of radio frequency spectrum without causing destructive interference to the licensed users. In
this paper we considered spectrum sensing of Digital Video Broadcast Terrestrial (DVB-T)
signal in different scenario. We compared various spectrum sensing algorithms that make use of
the second order statistics; the energy detector was also included for comparison. The results
show that it is possible to obtain good detection performance by exploiting the correlation
method.
Noise Immune Convolutional Encoder Design and Its Implementation in Tanner ijcisjournal
With the rapid advances in integrated circuit(IC) technologies, number of functions on a chip was
increasing at a very fast rate, with which interconnect density is increasing especially in functional logic
chips. The on-chip noise affects are increasing and needs to be addressed. In this paper we have
implemented a convolution encoder using a technique that provides higher noise immunity. The encoder
circuit is simulated in Tanner 15.0 with data rate of 25Mbps and a clock frequency of 250MHz
NOISE IMMUNE CONVOLUTIONAL ENCODER DESIGN AND ITS IMPLEMENTATIONIN TANNERIJCI JOURNAL
With the rapid advances in integrated circuit(IC) technologies, number of functions on a chip was increasing at a very fast rate, with which interconnect density is increasing especially in functional logic chips. The on-chip noise affects are increasing and needs to be addressed. In this paper we have implemented a convolution encoder using a technique that provides higher noise immunity. The encoder circuit is simulated in Tanner 15.0 with data rate of 25Mbps and a clock frequency of 250MHz
International Journal of Computational Engineering Research(IJCER)ijceronline
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology
Powerful business model for fixed wireless data using outdoor antennas - PaperAndre Fourie
Paper presented at the 2nd Africa Radio Comms Conference in Johannesburg - Nov 2015
By Andre Fourie
The revenue that can be generated by an LTE base station is influenced by the quality of the signal received by the customer premise equipment (CPE). Most CPE come with omni-directional indoor antennas, but have provision for the connection to external antennas.
Substituting the indoor antennas for directional outdoor antennas has a marked effect on the data transfer speeds of the network. There are two reasons for this. Firstly, outdoor antennas are physically larger than their indoor counterparts and thus have a higher gain. The increase in antenna gain translates directly to an increase in received signal strength. The second advantage is that the outdoor antenna sits in an environment that has much better propagating properties than the indoor antenna. Tests have shown that data speeds 3-5 times faster are possible using external antennas compared to indoor antennas.
It is shown, using a primitive financial model that fairly large financial gains can be made by equipping CPE devices with external antennas.
Advanced modulation coding schemes for an optical transceiver systems–based O...journalBEEI
This paper examines advanced modulation coding schemes for an optical transceiver systems–based optical wireless communication (OWC) channel model. These modulation techniquesinclude On-Off keying and return to zero (RZ)/non–return to zero (NRZ) coding. The signal power level against time and frequency spectral variations are measured. The max. Q factor and min. bit error rate (BER) are estimated and clarified for each modulation code scheme by using an optisystem simulation model. Transmission bit rates of up to 40 Gb/s can be achieved for possible distances up to 500 km with acceptable Q factor. The received power and max. Q factor are measured and clarified with OWC distance variations. The On-Off keying modulation code scheme resulted in better performance than the other modulation code schemes did.
To meet the demands of high speed required by mobile communication of past generations ,one solution is to increase the number of antennas to the show and the reception of the wireless link this is called MIMO (Multiple input ,Multiple output )technology .however ,the integration of multiple antennas on the same PCB is delicate because of the small volume that require some applications and electromagnetic antenna between the coupling ,phenomena that we cannot neglect them .indeed a strong isolation between them has been reached to reduce fading of the signal caused by the electromagnetic antenna reached to reduce fading of the signal caused by the electromagnetic coupling and maximize the overall gain .in this article we are interested then integration on the same printed circuit of eight antennas MIMO are not operation in the same frequency band .the first antenna of this last work at 2.4GHz .other antennas have resonance frequency folling each with 20MHz offset this device is characterized by its original form that keeps is highly isolated antennas from the point of view electromagnetic coupling
DESIGN AND OPTIMIZATION A CIRCULAR SHAPE NETWORK ANTENNA MICRO STRIP FOR SOME...ijcseit
To meet the demands of high speed required by mobile communication of past generations ,one solution is
to increase the number of antennas to the show and the reception of the wireless link this is called MIMO
(Multiple input ,Multiple output )technology .however ,the integration of multiple antennas on the same
PCB is delicate because of the small volume that require some applications and electromagnetic antenna
between the coupling ,phenomena that we cannot neglect them .indeed a strong isolation between them has
been reached to reduce fading of the signal caused by the electromagnetic antenna reached to reduce
fading of the signal caused by the electromagnetic coupling and maximize the overall gain .in this article
we are interested then integration on the same printed circuit of eight antennas MIMO are not operation in
the same frequency band .the first antenna of this last work at 2.4GHz .other antennas have resonance
frequency folling each with 20MHz offset this device is characterized by its original form that keeps is
highly isolated antennas from the point of view electromagnetic coupling
To meet the demands of high speed required by mobile communication of past generations ,one solution is
to increase the number of antennas to the show and the reception of the wireless link this is called MIMO
(Multiple input ,Multiple output )technology .however ,the integration of multiple antennas on the same
PCB is delicate because of the small volume that require some applications and electromagnetic antenna
between the coupling ,phenomena that we cannot neglect them .indeed a strong isolation between them has
been reached to reduce fading of the signal caused by the electromagnetic antenna reached to reduce
fading of the signal caused by the electromagnetic coupling and maximize the overall gain .in this article
we are interested then integration on the same printed circuit of eight antennas MIMO are not operation in
the same frequency band .the first antenna of this last work at 2.4GHz .other antennas have resonance
frequency folling each with 20MHz offset this device is characterized by its original form that keeps is
highly isolated antennas from the point of view electromagnetic coupling
Spectrally efficient multicarrier modulation system for visible light communi...IJECEIAES
Visible Light Communication (VLC) has become an accolade to its radio frequency counterpart. In VLC system, orthogonal frequency division multiplexing (OFDM) has drawn much attention, because of simple equalization, high spectral efficiency, high data rate and robustness to intersymbol interference (ISI). Besides, there are emerging applications that ought to be gotten with low latency and high reliability. To diminish power requirements with no transmission capacity extension, Trellis coded modulation (TCM) is utilized as a part of the framework in which the free distance of trellis diagram is equivalent to the minimum distance between the points of constellation focuses in partitioned subsets, which augments the coding gain up i.e. the performance parameter viably. TCM together with VLC-OFDM enhances the transmission execution in reasonable frameworks. In this paper, we propose OFDM which is based on TCM and is planned and exeuted for digitized OFDM frameworks by presenting delta sigma modulation (DSM) considering VLC channel. Simulation results show that the proposed TCM based VLC-OFDM offers incredible robustness against noises and nonlinear degradation.
COMPARISON OF BER AND NUMBER OF ERRORS WITH DIFFERENT MODULATION TECHNIQUES I...Sukhvinder Singh Malik
This paper provides analysis of BER and Number of Errors for MIMO-OFDM wireless communication system by using different modulation techniques. Wireless designers constantly seek to improve the spectrum efficiency/capacity, coverage of wireless networks, and link reliability. So the performances of the wireless communication systems can be enhanced by using multiple transmit and receive antennas, which is generally referred to as the MIMO technique. Here analysis will be carried out for an OFDM wireless communication system using different modulation techniques and considering the effect and the wireless channel like AWGN, fading. Performance results will be evaluated numerically and graphically using the plots of BER versus SNR and plots of number of errors versus SNR.
Michael Grigoropoulos, MSc Networks and Data Communications COURSEWORK, Kingston University
The purpose of this assignment is to analyze and simulate the physical layer of the 802.11a standard and compare the different modulation and coding schemes it can use. A theoretical approach of the protocol will be presented and also a practical simulation using Matlab and Simulink.
Reduction of Frequency offset Using Joint Clock for OFDM Based Cellular Syste...IJRST Journal
This project addresses the problem of clock synchronization between a base station (BS) and a mobile station (MS). A conventional technique for clock synchronization is that the MS clock is derived from the downlink signal originated from a base station. In cellular systems, a base station and mobile stations need to be synchronized before data exchange. Since the base station clock reference is more accurate, a mobile station typically derives its clock reference from the base station. But the carrier frequency offset due to Doppler shift may have harmful effects on the local clock derivation. This project proposes a joint clock and frequency synchronization technique between a base station and a mobile station, which is effective even with Doppler shift. We derive the joint estimation algorithm by analyzing the phase and the amplitude distortion caused by the sampling frequency offset and the carrier frequency offset. Simulation results showing the effectiveness of the proposed algorithm will also be presented.
THE PERFORMANCE OF CONVOLUTIONAL CODING BASED COOPERATIVE COMMUNICATION: RELAYIJCNCJournal
Wireless communication faces adversities due to noise, fading, and path loss. Multiple-Input MultipleOutput (MIMO) systems are used to overcome individual fading effect by employing transmit diversity. Duo to user single-antenna, Cooperation between at least two users is able to provide spatial diversity. This paper presents the evaluation of the performances of the Amplify and Forward (AF) cooperative system for different relay positions using several network topologies over Rayleigh and Rician fading channel. Furthermore, we present the performances of AF cooperative system with various power allocation. The results show that cooperative communication with convolutional coding shows an outperformance compared to the non-convolutional, which is a promising solution for high data-rate networks such as (WSN), Ad hoc, (IoT), and even mobile networks. When topologies are compared, the simulation shows that, linear topology offers the best BER performance, in contrast when the relay acts as source and the source take the relay place, the analysis result shows that, equilateral triangle topology has the best BER performance and stability, and the system performance with inter-user Rician fading channel is better than the performance of the system with inter-user Rayleigh fading channel.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
Comparing Evolved Extractive Text Summary Scores of Bidirectional Encoder Rep...University of Maribor
Slides from:
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Track: Artificial Intelligence
https://www.etran.rs/2024/en/home-english/
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
1. FACULTY OF ENGINEERING
DEPARTMENTS OF ELECTRONICS AND AUTOMATION
TECHNOLOGICAL EDUCATIONAL INSTITUTE OF PIRAEUS
MSc IN NETWORKING AND DATA COMMUNICATIONS
COURSEWORK
MODULE:
CI 7110 - Digital Communications
ID: K1465156
Module Coordinator:
Dr. H. Simos & Dr. Ch. Patrikakis
Date of Module:
14/5/2016
Name of Student:
Grigoropoulos Michail
Kingston University London
2. FACULTY OF ENGINEERING
DEPARTMENTS OF ELECTRONICS AND AUTOMATION
TECHNOLOGICAL EDUCATIONAL INSTITUTE OF PIRAEUS
Subject: Impulse Noise over xDSL Systems
Submission Date: 14/5/2016
Grade (%): ________________________________________________
% Grade reduction because of submission delay: _____
(5% Grade reduction per every day of Cwk delay).
Final Grade (%): ________________________________________
Kingston University London
3. Impulse Noise over xDSL Systems – MSc Networks & Data Communications - Kingston University London 3
Abstract - DSL technology provides high bit rate digital
services over the existing telephone lines without the need for
modifications to the customers facilities. Since the first field test
of DSL technology, it has been recognized that Impulse Noise
along with other impairments like attenuation and crosstalk, can
affect the achievable bit rate of DSL systems. [1]
The purpose of this assignment is to analyze and simulate the
impact of impulse noise on a DSL signal and the Impulse Noise
protection's impact on the achievable Bit-rate. How ISPs use
different "DSL profiles" on a customer's line to achieve better
data-rates and synchronization stability will also be presented. A
theoretical approach of the subject will be studied along with a
practical one with the use of Matlab and the internal DSLAM
Monitoring tool that a greek ISP company uses. Different "DSL
profiles" will be tested on a customer's line to extract
conclusions.
Keywords: Impulse Noise, Protection, INP, SNR Targeting, xDSL,
ISP, DSL Profiles, Data Rate, Bit-Rate
I. INTRODUCTION
DSL technology was developed in 1989 over the existing
widely spread telephone network so that no modifications to
the outer plant facilities would have to be made. This fact
would make it easier for the ISP to provide services and for
the customers to buy them but it would also import problems
to the venture because of the telephones network age,
condition and topology. [1]
Impairments such as crosstalk, attenuation, low SNR and
Impulse Noise are major afflictions to the transmission rate
and the stability of the synchronization. [2] Applications like
streaming video, Voice-over IP (VoIP) and video
conferencing are now more popular than ever. This type of
application is often referred to as 'time critical'. To work at
their best, time-critical applications require a stable connection
so data packets arrive at their destination consistently,
ensuring sounds and images flow without interruptions or
pauses. To mitigate the effects of Impulse Noise and low
SNR, ISPs use standard line profiles that suit each customer's
line to achieve higher data rates and service stability.
ADSL line profiles provide a range of pre-set line
configurations which allows the Internet Service Provider
(ISP) to fine tune the performance of its DSL service. They
are particularly useful if the customer experience drop outs or
data errors with their Internet connection.
II. BACKGROUND
A. Impulse Noise
Impulse Noise is a non-stationary, unpredictable burst noise
phenomenon that occurs in semiconductors and consists of
sudden step-like transitions between two or more discrete
voltage or current levels, as high as several
hundred microvolts, at random times. Impulse noise can be
caused from several sources, like on-off telephone hook
events, electrical appliances, transport vehicles or atmospheric
noise from electrical discharges and it usually creates an
electric Noise of 5-10 db.
Fig 1. Tx Waveform and Burst Noise
Even though due to its nature, Impulse Noise is very
difficult to be described statistically, several studies have been
conducted on the subject [3].
The impulse amplitude model is based on an approach
originally proposed by Henkel and Kessler, which consists of
approximating the voltage histograms with a generalized
exponential distribution of the form:
(1)
where u is the voltage and u0 a scaling parameter. This
model reflects well the fact that voltage distributions are
heavy-tailed and offers a good approximation for all measured
impulse noise voltage amplitude distributions collected in the
networks of both DT and BT. [4]
B. Impact of impulse noise on a DSL System
Impulse noise is an additive source that is only active for
very short intervals in time. If there is no interleaving, the FEC
cannot cope with the burst errors that the arrival of noise
impulses can produce. This can cause from noticeable
corruption of images or video services to loss of
synchronization. With the presence of interleaving and as its
depth rises, some errors can be corrected but still the effects of
the burst noise will be noticeable. Only with 64 step
interleaving almost all errors can be corrected but most
applications cannot tolerate the latency issues this depth of
interleaving causes.
Impulse Noise over xDSL Systems
Michail Grigoropoulos, MSc Networks and Data Communications, Kingston University
4. Impulse Noise over xDSL Systems – MSc Networks & Data Communications - Kingston University London 4
Fig 2. Error scatter plot. In the center we can see the effects of gaussion noise,
while on the outside circle, shows the impact of impulse noise.
Although the statistics of error free seconds do not change
significantly with various user data rates, the distribution of
the number of error free cells is. For different bit rates one unit
of time contains a different number of cells. At higher data
rates the distribution shifts towards larger number of
consecutive error free cells. This also means that Frame Error
Rate probability will be higher than Cell Error probability at
lower bit-rates with low depth interleaving, while on higher
depth interleaving, FER will be lower than CER. [5]
Fig 3. FER Probability Vs CER Probability
C. Impulse Noise Protection
INP parameter is a measure of the amount of protected /
recovered DMT symbols after a noise burst occurs. Various
INP techniques have been proposed.
RS-Erasure Decoding
Retransmission
Frame Blanking / Repetition.
An interleaver combined with an RS Decoder is a popular
scheme that is used widely by ISPs. This scheme ingresses
impulse noise with different code words sizes and variable
interleave depth.
The Reed-Solomon (N, N-R) is a linear block code which is
capable of correcting up to R/2 errors (R is no. of redundancy
bytes) within a codeword. An Interleaver and de-Interleaver
combination is used to spread the burst errors across several
codewords incurred by the Impulse noise. By increasing the
redundancy bits and interleaving dept, the coding gain in the
system increases and the effect of impulse noise on the signal,
is mitigated. Although, lower data-rates and higher delay
occurs by the process. The higher the INP requirement is, the
higher memory is needed and increase in delay occurs. [7]
Table 1. Rs Encoder Parameters
Fig 4. RS-Erasure Decoding
At the transmission layer, DMT symbols are of fixed
duration of 250 microseconds. The INPMin parameter defines
the minimum number of DMT symbols that will be protected
from impulse noise and thus the minimum duration of impulse
noise from which error correction should be able to recover.
For example, INP=2 can correct up to two successive
corrupted DMT symbols during one period of 250μs. To
provide maximum error protection, INPMin should be set as
high as possible without unduly compromising bitrates and
latency.
The INPmin setting is directly related with the symbol rate.
At higher values of INPmin, the circuit will be restricted to
lower maximum bit-rates. INP setting is related with FEC
parameters (interleaving depth and delay). With a good
combination of low delay and high INP, high stability of a
DSL line against burst noises, can be achieved. However, such
settings, forces the FEC parity ratio to 1/3 or 1/2 at the cost of
maximum data-rate and delay due to memory capacity and
processing speed requirements. More specifically, FEN, delay
and INP are related by the following equation. [8]
FEC parity ratio = ½ * (INP/Delay) (2)
Table 2. Max downstream related with INPmin and delay
5. Impulse Noise over xDSL Systems – MSc Networks & Data Communications - Kingston University London 5
III. SIMULATION OF IMPULSE NOISE
A. Simulink model
To simulate a burst noise and its effects on a DSL system,
the standard simulink's 256 ADSL ITU - T G.992.1 demo was
used. The original model was altered to simulate a burst
additive noise to the signal and measure the increase in BER
and FER.
Fig. 5 256 Channel ADSL - ITU - T G.992.1 Block diagram
For the simulation, the "Telephone Line" block was
changed. Two vector scopes were added to visualize the signal
without the impulse noise addition and the final transmitted
signal with the noise. To simulate the burst noise, a "Gaussian
Noise Generator" was used with 10 dB gain to amplify it and a
delay of -512 samples. A N-Sample Switch was used to adjust
the pulse duration and a Sum block to merge the impulse noise
with the original signal.
Fig. 6 Telephone line block diagram
A discrete-time scatter plot was also used inside the
demodulator block, to visualize the constellation and the noise
effect on it.
Fig. 7 Demodulator with Scatter plot block
B. Simulation
Running the simulation, two vector scopes and one scatter
scope open. The simulation runs with sampling time 0.5 and
2001 frames are transmitted. At first the original model
(without the impulse noise) was simulated.
Fig. 8 - Simulation without impulse noise
Fig. 9 - Scatter scope & Vector scope - No impulse noise
The constellation can be easily distinguished and the
signal's amplitude goes from -2 to 2 dB. BER is 5 x 10-4,
which
is an acceptable measurement.
Then, the model with the impulse noise addition was
simulated.
Fig 10. Simulation with impulse noise addtion
6. Impulse Noise over xDSL Systems – MSc Networks & Data Communications - Kingston University London 6
Fig 11. Scatter scope & Vector scope - No impulse noise
At the moment the impulse noise arrives, the constellation
cannot be distinguished at all and the signal's amplitude goes
from -10 to 10 dB. BER now is 8 x 10-3
. As for BER and FER,
the following results occurred:
No Impulse noise Impulse noise
Non
Interleaved
Interleaved
Non
Interleaved
Interleaved
Total Errors 986 910 1.326 x 10
4
1.346 x 10
4
Total Bits 1553 x 10
6
2.856 x 10
5
1.553 x 10
6
1.552 x 10
6
BER 0.000635 0.000586 0.008541 0.008674
#Error Frames 60 68 0.1111 92
Total Frames 2001 2001 2001 2001
FER 0.02999 0.03398 369 0.04598
Table 3. Simulation results (BER - FER)
IV. HOW INP AFFECTS CURRENT SYNCHRONIZATION
SPEED IN PRACTICE
A. Line Profiles
DSL lines are configured to a profile according to the
operating environment, the loop quality and the service
agreement. The ISPs technicians can configure each line to a
specific profile by accessing the DSLAM remotely through a
centralized system or automatically. [6]
A line profile consists of the following settings both for
upload and download:
Min/Max rate (Kbps)
Min/Max SNR
Target SNR
Impulse Noise Protection
Interleaving (Y/N)
Max Interleave delay
Many DSLAMs also support automated methods of
applying the best matching profile by measuring line's
characteristics based on historical performance. This method
is usually referred as Dynamic Line Management (DLM).
A greek ISPs internal DSLAM management system will be
used in this paper to test a customer's line to different profiles.
B. Applying profiles
For the needs of this assignment, access to a greek ISP's
internal DSLAM management system was granted. The
ADSL Measure tool was used to measure the effect of
interleaving and INP on a customer's line. The customer's
router synchronized at 10.255 Kbps (downstream) and 995
Kbps. So, profiles locked at Max. downstream rate 12.082
Kbps were used. The following line profiles were tested:
12 Mbps with no interleaving (Fast Path)
12 Mbps with Interleaving at 16ms
12 Mbps with Interleaving at 16ms and INP=1
12 Mbps with Interleaving at 16ms and INP=2
12 Mbps with Interleaving at 16ms and INP=4
12 Mbps WDLM no interleaving (Fast Path)
Table 4. Profile characteristics
In Table 4, each profile's configuration characteristics can
be found.
Screenshots from the ADSL Measure system:
Fig 12. 12 Mbps Fast path - No INP
7. Impulse Noise over xDSL Systems – MSc Networks & Data Communications - Kingston University London 7
Fig. 13. 12 Mbps with Interleaving - No INP
Fig 14. 12 Mbps with Interleaving - INP = 4
During the procedure, the following measurements were
taken:
Table 5. Live Measurements
V. RESULTS & DISCUSSION
Impulse noise is intermittent by nature, and much harder to
detect and analyze than traditional interference. It is a major
impairment for xDSL systems and can cause instability, loss
of synchronization, jitter and delay to services such as IPTV
and NoIP. Table 3 shows that a burst noise added to the signal,
can cause dramatic increase in BER. More corrupted data will
cause de-synch or corruption of image and sound that is
broadcasted through the xDSL system. Figure 11 confirms that
at the time an impulse noise occurs, data are completely
scattered and corrupted. Interleaving alone is not enough to
mitigate the effect.
ISPs use different INP methods to mitigate the effect of
burst noises. Choosing the right profile for each line is
significant for the line's stability and the ability to stream
video and voice services. The right profile would be the
profile with higher INP, lower delay, and with as high as
possible Maximum bit rate.
In Table 4, the tested profiles' characteristics are shown.
Choosing to deploy one of these profiles, sets the profiles
parameters in effect on the DSL system. The downstream
direction carries the IPTV picture and the VoIP sound and so
it is more important to protect against impulse noise than the
upstream direction. Higher INP settings will provide better
error protection if supported but may adversely impact
achievable bit rates and latency. Table 5 proves that as INP
rises, the Current Synchronization speed gets lower. Using the
WDLM Fast-path profile gave a higher data rate but left the
system exposed to impulse noises. The reason this profile
gives higher data-rates in comparison with the 12M_FAST
profile is that the 12M_FAST profile, has target SNR of 10 dB
while the WDLM Fast-path profile has target SNR of 8dB.
The WDLM profile will change automatically the target SNR
and enable interleaving when it will monitor the line's de-
synchronizations. This specific line seems to have de-synch
problems and with Interleaving enabled at the same target
SNR with the 12M FAST profile it seems to have a better
current synchronization data rate with INP of 1.5 symbols
(downstream) only from the interleaving factor. Since this line
is susceptible to outer burst noises, the best setting for it would
be the 12M INP 2 0 profile which would give 11344 Kbps
with 2 symbols protection and less delay than INP 4 but not
much more than INP 1.
Service providers and vendors thoroughly research their
environment in order to establish the appropriate profiles for
their own specific deployment. They test the performance of
any combination of parameters used in their profiles in order
to identify any impairments and adjust their profiles
accordingly.
8. Impulse Noise over xDSL Systems – MSc Networks & Data Communications - Kingston University London 8
REFERENCES
[1] J.-J. Werner, “Impulse noise in the loop plant,” in Proceedings of the
IEEE International
[2] W. Henkel, T. Kessler, “An Impulse-noise model - a proposal for
SDSL”, ETSI WG TM6 TD45 992T45A0, 1999
[3] D.B. Levey, S. McLaughlin, “Statistics of impulse noise: Interarrival
times”, ETSI WG TM6 TD19 993T19A0, 1999
[4] W. Henkel and T. Kessler, “Statistical description and modeling of
impulsive noise on the German telephone network,” IEE Electronics
Letters, vol. 30, pp. 935 – 936, June 1994
[5] Nedko H. Nedev, "Analysis of the Impact of Impulse Noise in Digital
Subscriber Line Systems", The University of Edinburgh
[6] Baofeng Frank Jiang, "Automated DSL Performance Adjustment"
United States Patent, Patent N0.: US 7,272,209 B2, Sep. 18, 2007
[7] Rahul Garg, Sunita Meena, Hemant Samdani and Patrick Duvaut,
"Impulse Noise Protection Initiatives in VDSL2 Systems, Conexant
Systems Inc., Feb. 2008
[8] Gavin Young, Dov Zimring, "TR-176 ADSL2Plus Configuration
Guidelines for IPTV", Broadband Forum - Technical report, Sep. 2008