This document discusses modulation techniques for ADSL modems. It begins with an abstract that introduces ADSL and the goal of evaluating modulation techniques to achieve high bandwidth.
The body of the document is divided into two main sections. The first section provides background on ADSL technology, including defining an ADSL modem and explaining how transmission rates vary based on distance from the local exchange.
The second section discusses modulation schemes used in ADSL modems, including phase-shift keying (PSK), quadrature amplitude modulation (QAM), and their basic receiver block diagrams. It provides equations to describe these modulation techniques.
PERFORMANCE OF WIMAX PHYSICAL LAYER WITH VARIATIONS IN CHANNEL CODING AND DIG...ijistjournal
The aim of this paper is to analyze the bit error rate (BER) performance of WiMAX physical layer with the implementation of different concatenated channel coding schemes under QAM and 16QAM digital modulations over realistic channel conditions (i.e. noise and multipath fading). In concatenated channel coding, the WiMAX system incorporates CRC-CC (Cyclic Redundancy Check and Convolutional) or RSCC (Reed-Solomon and Convolutional) encoder over an additative white gaussian noise (AWGN) and other multipath fading (Raleigh and Rician) channels. A segment of synthetic data is used for the analysis. Computer simulation results based on BER and signal to noise ratio (SNR) demonstrate that the performance of concatenated CRC-CC coded WiMAX system under QAM modulation is better as compared to RS-CC coded system over noisy and fading environments.
PERFORMANCE OF WIMAX PHYSICAL LAYER WITH VARIATIONS IN CHANNEL CODING AND DIG...ijistjournal
The aim of this paper is to analyze the bit error rate (BER) performance of WiMAX physical layer with the implementation of different concatenated channel coding schemes under QAM and 16QAM digital modulations over realistic channel conditions (i.e. noise and multipath fading). In concatenated channel coding, the WiMAX system incorporates CRC-CC (Cyclic Redundancy Check and Convolutional) or RSCC (Reed-Solomon and Convolutional) encoder over an additative white gaussian noise (AWGN) and other multipath fading (Raleigh and Rician) channels. A segment of synthetic data is used for the analysis. Computer simulation results based on BER and signal to noise ratio (SNR) demonstrate that the performance of concatenated CRC-CC coded WiMAX system under QAM modulation is better as compared to RS-CC coded system over noisy and fading environments.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Performance analysis of Multiband - OFDM systems using LDPC coder in pulsed -...IDES Editor
In this paper, a combined approach where low density
parity check (LDPC) codes are used to reduce the complexity
and power consumption of pulsed orthogonal frequencydivision
multiplexing (pulsed-OFDM) ultra-wideband (UWB)
systems is described. The proposed system uses LDPC codes
to achieve higher code rates without using convolution
encoding and puncturing thereby reducing the complexity and
power consumption of pulsed-OFDM system. The LDPCpulsed-
OFDM system achieves channel capacity with different
code rates and has good performance in different channel
fading scenarios. The pulsed OFDM system is used where
pulsed signals could spread the frequency spectrum of the
OFDM signal. The performance of LDPC-pulsed-OFDM
system for wireless personal area networks (WPAN) is
analyzed for different UWB indoor propagation channels (CM3
and CM4) provided by the IEEE 802.15.3a Standard activity
committee. To establish this, a design of LDPC-pulsed-OFDM
system using the digital video broadcasting-satellite-second
generation (DVB-S2) standard and provide the simulation
results for the different code rates supported by LDPC codes
is presented.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
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.
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.
Improving quality of service using ofdm technique for 4 th generation networkeSAT 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.
A Literature Survey on Comparative Analysis of RZ and NRZ Line Encoding over ...IJSRD
Modern world is the world of internet which requires more capacity and more bandwidth to modernize the world. Hence we move towards optical communication. When we talk about optical communication then chromatic dispersion is biggest obstacle for high speed optical channel. Chromatic dispersion can be reduced either by compensation technique [1, 2] or either by electronic dispersion compensation. In this paper, we make comparative analysis in RZ and NRZ line encoding over 40 Gbps system. Two different modulation formats including non-return-to-zero (NRZ), return-to-zero (RZ) is compared on the basis of Bit error rate and quality factor. The 40 Gbps signal is transmitted over 200 km in single mode fiber.
On the Performance Analysis of Multi-antenna Relaying System over Rayleigh Fa...IDES Editor
In this work, the end-to-end performance of an
amplify-and-forward multi-antenna infrastructure-based relay
(fixed relay) system over flat Rayleigh fading channel is
investigated. New closed form expressions for the statistics of
the received signal-to-noise ratio (SNR) are presented and
applied for studying the outage probability and the average
bit error rate of the digital receivers. The results reveal that
the system performance improves significantly (roughly 3 dB)
for M=2 over that for M=1 in both low and high signal-tonoise
ratio. However, little additional performance
improvement can be achieved for M>2 relative to M=2 at high
SNR.
International Journal of Engineering Research and Development (IJERD)IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
yahoo journals, bing journals, International Journal of Engineering Research and Development, google journals, hard copy of journal
Modelling of Crosstalk and Delay for Distributed RLCG On-Chip Interconnects F...IDES Editor
In order to accurately model high frequency affects,
inductance has been taken into consideration. No longer can
interconnects be treated as mere delays or lumped RC networks.
In that frequency range, the most accurate simulation model for
on-chip VLSI interconnects is the distributed RLC model.
Unfortunately, this model has many limitations at much higher
of operating frequency used in today’s VLSI design. The reduction
in cross-sectional dimension leads to more tightly couple
interconnects and therefore, a higher probability of unwanted
crosstalk interference. This can lead to inaccurate simulations
if not modelled properly. At even higher frequency, the aggressor
net carries a signal that couples to the victim net through the
parasitic capacitances. To determine the effects that this crosstalk
will have on circuit operation, the resulting delays and logic
levels for the victim nets must be computed. This paper proposes
a difference model approach to derive crosstalk and delay in the
transform domain. A closed form solution for crosstalk and delay
is obtained by incorporating initial conditions using difference
model approach for distributed RLCG interconnects. The
simulation is performed in 0.18μm technology node and an error
of less than 1% has been achieved with the proposed model when
compared with SPICE.
Coverage of WCDMA Network Using Different Modulation Techniques with Soft and...ijcnac
The wideband code division multiple access (WCDMA) based 3G cellular mobile
wireless networks are expected to provide a diverse range of multimedia services to
mobile users with guaranteed quality of service (QoS). To serve diverse quality of service
requirements of these networks it necessitates new radio resource management strategies
for effective utilization of network resources with coding schemes. In this paper coverage
area for voice traffic and with different modulation techniques, coding schemes and
decision decoder are discussed. These discussions are to improve the coverage area in
the mobile communication system. This paper is mainly focuses on coverage area of
WCDMA system using link budget calculation with different modulation, coding schemes
and decision decoder. Simulation results demonstrate coverage extension for voice
service with different modulation,coding scheme, soft and hard decision decoder using
appropriate Bit error rate (BER) to maintain QoS of the voice.
PERFORMANCE ANALYSIS OF QOS PARAMETERS LIKE PSNR, MAE & RMSE USED IN IMAGE TR...Journal For Research
Wireless designers constantly seek to improve the spectrum efficiency/capacity, coverage of wireless networks and link reliability. In this direction, Space-time wireless technology that uses multiple antennas along with appropriate signaling and receiver techniques that offers a powerful tool for improving the wireless performance is used in this thesis work. A special version of STBC called ‘Alamouti code’ is used. PSK modulation scheme is used for modulation of data. In this thesis work, the Space-Time Block Codes (STBC) is used in WLAN wireless network that uses multiple numbers of antennas at both transmitter and receiver. The STBC which includes the Alamouti Scheme for 2 transmit antenna and a different number of receiving antenna has been studied, simulated and analyzed. The simulation has been done in MATLAB. Throughput and several parameter performance has been analyzed using the MATLAB.A sample image is transmitted to compare the performance of various parameters like RMSE, PSNR, MAE etc. All the parameters are plotted against SNR (in dB) values ranging from -18 to 30. Various observations being made for the improvement in various parameters with increasing SNR and/or with changing diversity scheme. AWGN channel is used here for communication of sampled image data.
Non-binary codes approach on the performance of short-packet full-duplex tran...IJECEIAES
This paper illustrates the enhancement of the performance of short-packet full-duplex (FD) transmission by taking the approach of non-binary low density parity check (NB-LDPC) codes over higher Galois field. For the purpose of reducing the impacts of self-interference (SI), high order of modulation, complexity, and latency decoder, a blind feedback process composed of channels estimation and decoding algorithm is implemented. In particular, this method uses an iterative process to simultaneously suppress SI component of FD transmission, estimate intended channel, and decode messages. The results indicate that the proposed technique provides a better solution than both the NB-LDPC without feedback and the binary LDPC feedback algorithms. Indeed, it can significantly improve the performance of overall system in two important factors, which are bit-error-rate (BER) and mean square error (MSE), especially in high order of modulation. The suggested algorithm also shows a robustness in reliability and power consumption for both short-packet FD transmissions and high order modulation communications.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Performance analysis of Multiband - OFDM systems using LDPC coder in pulsed -...IDES Editor
In this paper, a combined approach where low density
parity check (LDPC) codes are used to reduce the complexity
and power consumption of pulsed orthogonal frequencydivision
multiplexing (pulsed-OFDM) ultra-wideband (UWB)
systems is described. The proposed system uses LDPC codes
to achieve higher code rates without using convolution
encoding and puncturing thereby reducing the complexity and
power consumption of pulsed-OFDM system. The LDPCpulsed-
OFDM system achieves channel capacity with different
code rates and has good performance in different channel
fading scenarios. The pulsed OFDM system is used where
pulsed signals could spread the frequency spectrum of the
OFDM signal. The performance of LDPC-pulsed-OFDM
system for wireless personal area networks (WPAN) is
analyzed for different UWB indoor propagation channels (CM3
and CM4) provided by the IEEE 802.15.3a Standard activity
committee. To establish this, a design of LDPC-pulsed-OFDM
system using the digital video broadcasting-satellite-second
generation (DVB-S2) standard and provide the simulation
results for the different code rates supported by LDPC codes
is presented.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
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.
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.
Improving quality of service using ofdm technique for 4 th generation networkeSAT 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.
A Literature Survey on Comparative Analysis of RZ and NRZ Line Encoding over ...IJSRD
Modern world is the world of internet which requires more capacity and more bandwidth to modernize the world. Hence we move towards optical communication. When we talk about optical communication then chromatic dispersion is biggest obstacle for high speed optical channel. Chromatic dispersion can be reduced either by compensation technique [1, 2] or either by electronic dispersion compensation. In this paper, we make comparative analysis in RZ and NRZ line encoding over 40 Gbps system. Two different modulation formats including non-return-to-zero (NRZ), return-to-zero (RZ) is compared on the basis of Bit error rate and quality factor. The 40 Gbps signal is transmitted over 200 km in single mode fiber.
On the Performance Analysis of Multi-antenna Relaying System over Rayleigh Fa...IDES Editor
In this work, the end-to-end performance of an
amplify-and-forward multi-antenna infrastructure-based relay
(fixed relay) system over flat Rayleigh fading channel is
investigated. New closed form expressions for the statistics of
the received signal-to-noise ratio (SNR) are presented and
applied for studying the outage probability and the average
bit error rate of the digital receivers. The results reveal that
the system performance improves significantly (roughly 3 dB)
for M=2 over that for M=1 in both low and high signal-tonoise
ratio. However, little additional performance
improvement can be achieved for M>2 relative to M=2 at high
SNR.
International Journal of Engineering Research and Development (IJERD)IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
yahoo journals, bing journals, International Journal of Engineering Research and Development, google journals, hard copy of journal
Modelling of Crosstalk and Delay for Distributed RLCG On-Chip Interconnects F...IDES Editor
In order to accurately model high frequency affects,
inductance has been taken into consideration. No longer can
interconnects be treated as mere delays or lumped RC networks.
In that frequency range, the most accurate simulation model for
on-chip VLSI interconnects is the distributed RLC model.
Unfortunately, this model has many limitations at much higher
of operating frequency used in today’s VLSI design. The reduction
in cross-sectional dimension leads to more tightly couple
interconnects and therefore, a higher probability of unwanted
crosstalk interference. This can lead to inaccurate simulations
if not modelled properly. At even higher frequency, the aggressor
net carries a signal that couples to the victim net through the
parasitic capacitances. To determine the effects that this crosstalk
will have on circuit operation, the resulting delays and logic
levels for the victim nets must be computed. This paper proposes
a difference model approach to derive crosstalk and delay in the
transform domain. A closed form solution for crosstalk and delay
is obtained by incorporating initial conditions using difference
model approach for distributed RLCG interconnects. The
simulation is performed in 0.18μm technology node and an error
of less than 1% has been achieved with the proposed model when
compared with SPICE.
Coverage of WCDMA Network Using Different Modulation Techniques with Soft and...ijcnac
The wideband code division multiple access (WCDMA) based 3G cellular mobile
wireless networks are expected to provide a diverse range of multimedia services to
mobile users with guaranteed quality of service (QoS). To serve diverse quality of service
requirements of these networks it necessitates new radio resource management strategies
for effective utilization of network resources with coding schemes. In this paper coverage
area for voice traffic and with different modulation techniques, coding schemes and
decision decoder are discussed. These discussions are to improve the coverage area in
the mobile communication system. This paper is mainly focuses on coverage area of
WCDMA system using link budget calculation with different modulation, coding schemes
and decision decoder. Simulation results demonstrate coverage extension for voice
service with different modulation,coding scheme, soft and hard decision decoder using
appropriate Bit error rate (BER) to maintain QoS of the voice.
PERFORMANCE ANALYSIS OF QOS PARAMETERS LIKE PSNR, MAE & RMSE USED IN IMAGE TR...Journal For Research
Wireless designers constantly seek to improve the spectrum efficiency/capacity, coverage of wireless networks and link reliability. In this direction, Space-time wireless technology that uses multiple antennas along with appropriate signaling and receiver techniques that offers a powerful tool for improving the wireless performance is used in this thesis work. A special version of STBC called ‘Alamouti code’ is used. PSK modulation scheme is used for modulation of data. In this thesis work, the Space-Time Block Codes (STBC) is used in WLAN wireless network that uses multiple numbers of antennas at both transmitter and receiver. The STBC which includes the Alamouti Scheme for 2 transmit antenna and a different number of receiving antenna has been studied, simulated and analyzed. The simulation has been done in MATLAB. Throughput and several parameter performance has been analyzed using the MATLAB.A sample image is transmitted to compare the performance of various parameters like RMSE, PSNR, MAE etc. All the parameters are plotted against SNR (in dB) values ranging from -18 to 30. Various observations being made for the improvement in various parameters with increasing SNR and/or with changing diversity scheme. AWGN channel is used here for communication of sampled image data.
Non-binary codes approach on the performance of short-packet full-duplex tran...IJECEIAES
This paper illustrates the enhancement of the performance of short-packet full-duplex (FD) transmission by taking the approach of non-binary low density parity check (NB-LDPC) codes over higher Galois field. For the purpose of reducing the impacts of self-interference (SI), high order of modulation, complexity, and latency decoder, a blind feedback process composed of channels estimation and decoding algorithm is implemented. In particular, this method uses an iterative process to simultaneously suppress SI component of FD transmission, estimate intended channel, and decode messages. The results indicate that the proposed technique provides a better solution than both the NB-LDPC without feedback and the binary LDPC feedback algorithms. Indeed, it can significantly improve the performance of overall system in two important factors, which are bit-error-rate (BER) and mean square error (MSE), especially in high order of modulation. The suggested algorithm also shows a robustness in reliability and power consumption for both short-packet FD transmissions and high order modulation communications.
Performance of OFDM System under Different Fading Channels and Channel CodingjournalBEEI
Orthogonal frequency division multiplexing (OFDM) is a type of multicarrier modulation (MCM) technique in which larger bandwidth is divided into parallel narrow bands each of which is modulated by different subcarriers. All the subcarriers are orthogonal to each other and hence it reduces the interference among various subcarriers. OFDM technique is an efficient modulation technique used in certain wired and wireless application.In a wireless communication channel, the transmitted signal can travel from transmitter to receiver over multiple reflective paths. This results to multipath fading which causes fluctuations in amplitude, phase and angle of arrival of the received signal. For example, the signal which is transmitted from BTS (base transceiver station) may suffer multiple reflections from the buildings nearby, before reaching the mobile station. Such multipath fading channels are classified into slow fading/fast fading and frequency-selective/flat fading channels. This paper discusses the performance of OFDM system using various fading channels and channel coding. The parameter which is known as Bit error rate (BER) is calculated under different fading channels (AWGN, Rayleigh and Rician) for different digital modulation (BPSK, QPSK and QAM) and Channel coding (linear/Cyclic coding). Matlab Simulink tool is used to calculate the BER parameter.
The aim of this paper is to determine the viability of Indoor Optical Wireless Communication System. This paper introduces Visible Light Communication along with its merits, demerits and applications. Then the main characteristics of VLC system are described, around which the project is designed. Multiple Input-Multiple Output (MIMO) technique is used in the project in order to enhance the data rate of transmission. Instead of using a system of only one LED and one APD, which transmits only one bit at a time, a system of 4 LEDs and 4 APDs is introduced, which increases the data rates by 300% from the previous case. We observe the signal, noise, SNR, BER etc. across the room dimension. Finally, in the last chapter we summarize our results on the basis of MATLAB simulations and propose some modifications to this model that can be implemented in future.
Modelling and QoS-Achieving Solution in full-duplex Cellular SystemsIJCNCJournal
The global bandwidth scarcity and the ever-growing demand for fast wireless services have motivated the quest for new techniques that enhance the spectral efficiency (SE) of wireless systems. Most conventional SE increasing methods (e.g., adaptive modulation and coding) have already been exhausted. Single-channel full-duplex (SCFD) communication is a new attractive approach in which each node may simultaneously receive and transmit over the same frequency channel, and thus, it has the potential to double the current SE figures. In this paper, we derive a model for the signal-to-interference-plus-noise ratio (SINR) in a SCFD-based cellular system with imperfect self-interference cancellation. Furthermore, given a set of uplink and downlink quality of service requirements, we answer the following two fundamental questions. First, is this set achievable in the SCFD-based cellular system? Second, if the given set is achievable, what is the optimal achieving policy? To that end, we provide a unified model for the SCFD-based cellular system, and give insights in the matrix of interference channel gains. Simulation results suggest that depending on the locations of the users, a combination of full-duplex and half-duplex modes over the whole network is more favourable policy
A High Performance Hybrid Two Dimensional Spectral/Spatial NZCC/MD Code for S...IJCNCJournal
This paper proposes a new technique to construct a hybrid zero cross-correlation (NZCC) based on multiple diagonal (MD) code for two-dimensional (2D) spectral amplitude coding for optical code division multiple access code division multiple access (SAC-OCDMA) systems. The proposed hybrid code eliminates totally the multiple access interference (MAI) between a large number of users and allows them to connect simultaneously via the optical communication link with a high speed to receive huge data and serve various areas such as Internet, telephony, DAB radio, digital audio broadcasting, and DVB video. Simulation results demonstrate that the performance of such a SAC-OCDA system based on novel 2D hybrid NZCC/MD code can be easily improved keeping a less complex structure using couplers for direct spectral/spatial dimension (SDD) detection and show superior bit error rate (BER) values comparing to previously developed two-dimensional codes including perfect difference (2D-PD), diagonal Eigen-value units (2D-DEU), multi-service (2D-MS) and balanced incomplete block design (2D-BIBD) codes.
A HIGH PERFORMANCE HYBRID TWO DIMENSIONAL SPECTRAL/SPATIAL NZCC/MD CODE FOR S...IJCNCJournal
This paper proposes a new technique to construct a hybrid zero cross-correlation (NZCC) based on
multiple diagonal (MD) code for two-dimensional (2D) spectral amplitude coding for optical code division
multiple access code division multiple access (SAC-OCDMA) systems. The proposed hybrid code
eliminates totally the multiple access interference (MAI) between a large number of users and allows them
to connect simultaneously via the optical communication link with a high speed to receive huge data and
serve various areas such as Internet, telephony, DAB radio, digital audio broadcasting, and DVB video.
Simulation results demonstrate that the performance of such a SAC-OCDA system based on novel 2D
hybrid NZCC/MD code can be easily improved keeping a less complex structure using couplers for direct
spectral/spatial dimension (SDD) detection and show superior bit error rate (BER) values comparing to
previously developed two-dimensional codes including perfect difference (2D-PD), diagonal Eigen-value
units (2D-DEU), multi-service (2D-MS) and balanced incomplete block design (2D-BIBD) codes.
OPTICAL SWITCHING CONTROLLER USING FPGA AS A CONTROLLER FOR OCDMA ENCODER SYSTEMEditor IJCATR
This paper proposed a design of optical switching controller using FPGA for OCDMA encoder system. The encoder is one
of the new technologies that use to transmit the coded data in the optical communication system by using FPGA and optical switches.
It is providing a high security for data transmission due to all data will be transmitting in binary code form. The output signals from
FPGA are coded with a binary code that given to an optical switch before it signal modulate with the carrier and transmit to the
receiver. In this paper, AA and 55 data were used for source 1 and source 2. It is generated sample data and sent packet data to the
FPGA and stored it into RAM. The simulation results have done by using software Verilog Spartan 2 programming to simulate. After
that the output will produces at waveform to display the output. The main function of FPGA controlling unit is producing single pulse
and configuring optical switching system.
Performance analysis of negative group delay network using MIMO techniqueTELKOMNIKA JOURNAL
This study introduces comparative consequences that determine the bit error rate enhancements, resultant from adopting a proposed MIMO wireless model in this study. The antenna configurations for this model uses new small microstrip slotted patch antenna with multiple frequency bands at strategic operating frequencies of 2.4, 4.4, and 5.55 respectively. The S11 response of the proposed antenna for IEEE802.11 MIMO wireless network has been highly appropriate to be adopted with MIMO antenna system. The negative group delay (NGD) response is the most significant feature for projected MIMO antenna. The NGD stands for a counterintuitive singularity that interacts time advancement with wave propagation. These improvements are employed for increasing a reliability of instantly conveyed data streams, enhance the capacity of the wireless configuration and decrease the bit error rate (BER) of adopted wireless system. In addition to antenna scattering response, the enhancements have been analysed in term of BER for different MIMO topologies.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
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Design and Performance Evaluation Of Modulation Techniques Suitable For ADSL modem
1. World Academy of Science, Engineering and Technology 62 2012
Design and Performance Evaluation
Of Modulation Techniques Suitable
For ADSL modem.
Mr. Ashraf S M Touba Prof. Ivan Bagaric
technologies. Each of the DSL technologies mixes
Abstract — One of the significant problems in ADSL modem different. Asymmetrical digital subscriber line (ADSL) is a
design is the demand for bandwidth for high speed data communication system that transfers both analog and
communications and interactive media transmission which digital information on a copper wire pair. The analog
has been growing explosively. The objective of this paper , is information can be a standard POTS or ISDN signal. The
to achieve the high bit rate in demand of bandwidth which
maximum downstream digital transmission rate (data rate
depends on design and evaluating the Modulation /
Demodulation – Regardless of the including any types of
to the end user) can vary from 1.5 Mbps to 9 Mbps
coding techniques and Filters - and simulated reaching to the downstream and the maximum upstream digital
appropriated technique which will has been considered to transmission rate (from the customer to the network) varies
design requirements of ADSL Up/Down stream specifications from 16 kbps to approximately 800 kbps. The data
using Matlab coding . transmission rate varies depending on distance, line
Keywords — ADSL ,Up /Down stream, Mathlab, Bit rate. distortion and settings from the ADSL service provider.
I. INTRODUCTION II. ADSL TECHNOLOGY.
Digital subscriber line is the transmission of digital A. What does meaning of ADSL Modem?
information, usually on a copper wire pair. Although the The idea behind the Asymmetrically that In ADSL, the
transmitted information is in digital form, the transmission data throughput in the upstream direction, (the direction to
medium is usually an analog carrier signal (or the the service provider) is lower, hence the designation
combination of many an analogue carrier signals) that is of asymmetric service, Figure 1 shown the means of
modulated by the digital information signal. Digital Asymmetrically ;the digital data sent over analogy media
subscriber line (DSL) was first used in the 1960s to that enables faster data transmission over copper telephony
describe the T-1 circuits that were extended to the line than a conventional voice band modem can provide. It
customer premises. Later the same term was used to does this by utilizing frequencies that are not used by a
describe ISDN basic rate interface (BRI) (2B+D, 144 voice telephone call that will being the subscriber line
Kbps) and primary rates interface (PRI) (23B+D, 1.544 same to on the lines. In general; the speed factors depend
Mbps). There are several different digital subscriber line type and thickness of copper wire ,situation of carrying
technologies. Each of these DSL technologies usually has a wire (external noises and interfaces)and depends on the
prefix to indicate the specific variant of DSL technology. distance from the local exchange , maximum range of
Hence, the “x” in xDSL indicates that there are many
ADSL without a repeater is 5.5Km,as a distance decreases
forms of xDSL technology. DSL transmission allows high-
toward the telephone company office the data rate
speed data transmission over existing twisted pair
telephone wires. This has the potential providing high- increases .
speed data services without the burden of installing new In July 2002, the ITU completed G.992.3 and G.992.4,
transmission lines (e.g., for Internet access). DSL service two new standards for ADSL technology collectively
dramatically evolved in the mid 1990s due to the called “ADSL2”. In January 2003, as users of ADSL
availability of new modulation technology and low cost chipsets based on the first generation of ADSL standards
electronic circuits that can do advanced signal processing passed the 30-million mark, G.992.5 officially joined the
(e.g., echo canceling and multiple channel demodulation). ADSL2 family as ADSL2plus, (or ADSL2+ as it is
This has increased the data transmission capability of commonly known).Several other features and
twisted pair copper wire to over 50 Mbps. improvements were also incorporated in the form of new
The data transmission capability of a DSL system varies Annexes. Carriers, service providers,[6] and subscribers
based on the distance of the cable, type of cable used, and have played a key role in the completion of ADSL2,
modulation technology. There are several different DSL having provided valuable feedback from the field that the
ITU in turn incorporated into the standards in the form of
Ashraf Touba PhD student, University of Singidunum ,Belgrade ,Serbia new features and performance improvements.
(E-mail: asmg28@gmail.com).
Ivan Bagaric ,Full professor ,University of Singidunum ,Belgrade,Serbia
(E-mail: ibagaric@singidunum.ac.rs).
1956
2. World Academy of Science, Engineering and Technology 62 2012
Fig.2. Constellation diagram for MPSK
(Illustrated for M=8).
Fig.1. The Downstream/Up stream of ADSL Modem
Each message point is spaced (2π/M) distance from its
adjacent message point. The receiver block diagram of
B. The Modulation schemes are used in ADSL MPSK is given below:
Modem.
Digital modulation schemes are classified into two large
categories: constant envelope and non-constant envelope.
Under constant envelope class, there are three subclasses:
FSK, PSK, and CPM. Under non-constant envelope class,
there are three subclasses: ASK, QAM, and other non-
constant envelope modulations. In M-ary phase shift
keying systems, the phase of the carrier is allowed to take Fig.3. Receiver Block diagram for MPSK.
on one of the (M) possible values;
Since the in-phase and quadrature components of M-ary
(1) QAM are independent, the Pc(1-Pe)2 where the Pe is the
probability of error of either component. The constellation
Thus (M) possible signals that would be transmitted during for the in-phase (or) quadrature component has geometry
each has signaling interval of similar to (PAM) with corresponding number of amplitude
(T) is: levels.
Consider a quaternary signaling scheme in which the
(2) received signal is defined by x(t) =ai+w(t);0≤ t ≤T Where
the amplitude ai = ± a/2 ± 3a/2 and w(t)is the sample
function of a white Gaussian noise process of zero mean
E =energy per symbol and usually M is taken as power of 2
and power spectral density N0/2. The signal space,
i.e. M =2k .
representing the signal component of x(t) has two
Recognizing that each Sk(t) may be written in terms of a
characteristic features. It is one-dimensional in that the
sinusoid and co-sinusoid , which are orthogonal and then
signal component is scaled of time function;
suitably scaling to fulfill the conditions of
(3)
(8)
The appropriate form for the orthogonal waveforms
φi(t) and φj(t) is given by : There are four message points,
(9)
(4)
(5)
The signal space diagram is as depicted below:
The coordinates of the message points can be calculated by
(6)
(7)
A constellation diagram is a representation of a signal
modulated by a digital modulation scheme. It displays the
signal as a two-dimensional scatter diagram in the complex Fig.4 Signal Space diagram for M -ary QAM.
plane at symbol sampling instants thus will given as :
1957
3. World Academy of Science, Engineering and Technology 62 2012
C. Spectrum (Bandwidth) Requirements. meet the (ITU G.992.4) as standard for splitter less
The signal bandwidth for the communications channel ADSL2 with data rate mandatory capability reduced to
needed depends on the symbol rate, not on the bit rate. 1.536 Mb/s downstream , 512Kb/s Up stream. That
An example of how symbol rate influences spectrum modem considered the 512-QAM Modulation in Upstream
requirements can be seen in eight-state Phase Shift Keying and 1024-QAM downstream in AWGN channel without
(8PSK). It is a variation of PSK. The phase of the signal any types of filters, Error correction code and
can take any of eight values at any symbol time. Since 23= decode…etc.
8, there are three bits per symbol. This means the symbol
rate is one third of the bit rate. This is relatively easy to
decode. Bandwidth efficiency describes how efficiently the
allocated bandwidth is utilized or the ability of a
modulation scheme to accommodate data, within a limited
bandwidth, as shown in ( table 1) below the theoretical
bandwidth efficiency limits for the main modulation types;
as we have more number of bits per symbol means the
modulation will increasing in the order and the following
bandwidth efficiency of power spectrum density has
Fig.6. Modem design of M-QAM
reduced powerfully as shown in (Figure 5)
Table 1. Bandwidth efficiency corresponding to
the symbol rate .
Modulation Theoretical Bandwidth
Format Efficiency limits
BPSK 1 bit/sec/Hz
QPSK 2 bit/sec/Hz
8 PSK 3 bit/sec/Hz
16 PSK 4 bit/sec/Hz
32 PSK 5 bit/sec/Hz
Fig.7(a) Time domain waveforms of 16QAM
Fig.5 Power Spectrum of Selected M-ary Modulation
Schemes.
III. DESIGN AND IMPLEMENTATION
Clearly have been identified that to producing an ADSL
modem which has a efficient bandwidth meeting a higher
bit data rate should design the proper digital modulation
.In this paper that examined each type of M-ray Mod/Dem
practically .The different types of M-ray Modem start by
BPSK to 256 QAM ; that has been designed separately in
terms of Modem design as shown in (Figure .6)
,Time/Frequency domain waveforms as shown in Fig.7(b)Frequency domain waveforms of
(Figure.7), Bit error rate (BER) in theoretically and 16QAM
practically as shown in (Figure .8) the bit error rate for M-
QAM starting with BPSK to 1024 QAM ; theoretical and
simulation. The proper modem which has been chosen to
1958
4. World Academy of Science, Engineering and Technology 62 2012
The modem has been designed and the parameters
calculated to introducing the simulated frequency spectrum
which measured from null to null approach as upstream
part of 512 QAM ,Downstream of 1024QAM The
practical frequency spectrum shown in (Figure .10) is
clearly demonstrated the availability of high order
modulation as feature to have high data rate in amount of
channel bandwidth.
IV. CONCLUSION
Fig.8 The theoretical and practical BER of M-QAM
The needs of the broadband come to involves of digital
The consideration parameters and result of simulation of modulation techniques, which most have been worked out
specifically ADSL2 Modem shown in (table.2). the range to get acquainted which best modem could be considered
of down/up streams will have bandwidth channels (960 to leads to have the appropriate bandwidth efficiency as
kHz , 116 kHz) respectively; ITU G.992.4 ADSL2 increasing of order of M-ary. The aim of these paper to
Modem theoretically spectrum shown in (Figure.9). introduce the main process of efficient design that could
uses as base which easily implemented with any filters
Table .2 the design parameters and results. ,error correction parts to enhancing data rate and less
complexity .
ADSL Data Channel Ratio of M-ray
Parameters Rate(Rb) Bandwidth(B (2Rb/2) technique REFERENCES
)
[1] T. Starr, J. M. Cioffi, and P. Silverman,
Upstream 520Kb/s 116kHz 9 512QAM Understanding Digital Subscriber Line Technology,
Prentice-Hall PTR, USA, 1999.
Downstream [2] J. M. Cioffi, “A multicarrier primer”, White Paper,
4.5Mbps 960kHz 10 1024QAM
Amati Communications Corporation and Stanford
University, Nov 1999.
[3] Nextep Broadband Networks Group, “XDSL
modulation technique ,May 2001.
[4] R. Laroia, S. Trenter, and N. Farvardin, “A Simple
and Effective Preceding Scheme for Noise Whitening
on Inter symbol Interference.
[5] IEEE Spectrum , Always on - Living in a networked
World, Vol 38, No. 1, January 2001.
[6] The Jamaica Gleaner, Centennial to invest $millions
in Jamaica June 26, 2001.
[7] Cable and Wireless Jamaica, Reference Interconnect
Fig .9. The theoretical frequency spectrum considered Offer (RIO).
[8] Jianhau Lu, K. B. Letaif, Justin C-I Chuang, Ming L.
Liou, “MPSK and M-QAM BER Computation
Using Signal-Space Concepts”, IEEE Trans. Com.,
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System for ADSL Transmission on Metallic Local
Loops with Provisioning to Facilitate Installation and
Operation in Conjunction with Other Services.”
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Fig .10 ITU G.992.4 ADSL2, simulated spectrum Conference March 25-29, 2007 TUNISIA.
1959