In this paper, optical CDMA which combines the large bandwidth of the fibre medium with the flexibility of the
CDMA technique to achieve high speed connectivity has been used. For achieving this purpose, OPPM
signalling and switching techniques have been employed. This helps in the achievement of high tolerance to
Multiple Access Interference, further resulting in improvement of both the Bit Error Rate and optical channel
capacity without the need to decrease the light pulse width. An OPPM scheme to support multimedia services
with different transmission rates and Quality of Service requirements is proposed. Packet Switching technique
has been employed to help in the transfer of data in the form of packets from the source to the destination via a
specified route. The results are calculated by using PPM signalling and switching technology.But switching
technology has been found to be far better than the OOK-OCDMA if the average power has been considered as
the restraining factor.
This document discusses and compares wireless communication technologies including OFDMA, SC-FDMA, CDMA, and LTE. It provides an overview of these technologies, how they have evolved over time, and their performance. Key points discussed include how LTE uses OFDMA for downlinks and SC-FDMA for uplinks, the benefits of MIMO techniques for improving spectral efficiency, and methods for estimating signal-to-noise ratio to enable adaptive modulation schemes. The document also includes figures comparing parameters of various wireless standards.
Multi User Detection in CDMA System Using Linear and Non Linear DetectorWaqas Tariq
DS-Code division multiple access is considered as the third generation of cellular mobile used in interim standard 95(IS-95) [1]and it is currently being standardized for universal mobile telecommunication systems (UMTS). CDMA offers attractive features, such as frequency reuse, soft handoff, increased capacity, and multipath combating. In a CDMA system, several users simultaneously transmit information over a common channel using pre-assigned codes. The conventional single user detector consists of a bank of filters matched to the spreading codes. This detector suffers from two problems. First, multiple access interference (MAI) produced by the other co-channel users is a significant limitation to the capacity of this detector. The second problem is the near-far effect which occurs when the relative received power of interfering signals becomes larger. A potential solution is multi-user detection which exploits the information of signals of interfering users. In the present study performance of various linear detectors like matched filter detector, MMSE detector, and adaptive LMS detector are studied. These are the linear detectors that operate linearly on the received signal statistics and are suboptimal detectors. The matched filter bank is the conventional detector and offers the simplest way of demodulating CDMA signals .The detector resulting from the MMSE (minimum mean square error) criterion shows better performance over the conventional one for low SNR value. Adaptive LMS is employed to enhance the BER performance in MUD application.Several factors motivated the research to apply neural network as multi-user detector. NN are nonlinear classifier in addition to being adaptive and computationally efficient. The performance of two layer perceptron neural network using BP learning rule is used for multi-user detection of CDMA signals in AWGN channels. The neural network detectors show improvement of BER in the comparative analysis done in the present work. and offers further research scope for solving multi-user detection problems in CDMA application.
HYPERSPECTRAL IMAGERY CLASSIFICATION USING TECHNOLOGIES OF COMPUTATIONAL INTE...IAEME Publication
Texture information is exploited for classification of HSI (Hyperspectral Imagery) at high spatial resolution. For this purpose, framework employs to LBP (Local Binary Pattern) to extract local image features such as edges, corners & spots. After the extraction of LBP feature two levels of fusions are applied along with Gabor feature & spectral feature, i.e. Feature level fusion & Decision level fusion. In Feature level fusion multiple features are concurred before pattern classification. While in decision level fusion, it works on probability output of each individual classification pipeline combines the distinct decisions into final one. Decision level fusion consists of either hard fusion, soft fusion method. In hard fusion we consider majority part & in soft fusion linear logarithmic opinion pool at probability level (LOGP). In addition to this, extreme learning machine (ELM) classifier is included which is more efficient than support vector machine (SVM), used to provide probability classification output. It has simple structure with one hidden layer & one linear output layer. ELM trained much faster than SVM.
The document discusses various literature on OFDM and MC-CDMA techniques. It summarizes 17 research papers on topics like using wavelet packets instead of Fourier transform in MC-CDMA to improve bandwidth efficiency and reduce interference. It also discusses using techniques like DWT, Radon transform, and antenna diversity with MC-CDMA and comparing the BER performance of different approaches in various channel conditions like AWGN, Rayleigh fading and frequency selective fading channels. The rationale given is that replacing Fourier transform with wavelet packets in MC-CDMA can eliminate the need for cyclic prefix and improve spectral efficiency.
The document surveys 17 literature sources on multi-carrier modulation techniques like OFDM and MC-CDMA. Several sources propose using wavelet transforms instead of Fourier transforms to improve bandwidth efficiency and reduce interference for MC-CDMA systems. Simulation results from the literature show that wavelet packet based MC-CDMA can outperform FFT based MC-CDMA in terms of lower bit error rates, especially in frequency selective fading channels. The rationale given is that wavelet transforms eliminate the need for cyclic prefixes, thereby improving spectral efficiency over traditional MC-CDMA schemes.
ESTIMATION AND COMPENSATION OF INTER CARRIER INTERFERENCE IN WIMAX PHYSICAL L...ijngnjournal
WiMAX is Wireless Interoperability for Microwave Access has emerged as a promising solution for transmission of higher data rates for fixed and mobile applications. IEEE 802.16d and e are the standards proposed by WiMAX group for fixed and mobile. As the wireless channel have so many limitation Such as Multipath, Doppler spread, Delay spread and Line Of Sight (LOS)/Non Line Of Sight (NLOS) components. To attain higher data rates the Multi Carrier System with Multiple Input and Multiple Output (MIMO) is incorporated in the WiMAX. The Orthogonal Frequency Division Multiplexing (OFDM) is a multi carrier technique used with the WiMAX systems. In OFDM the available spectrum is split into numerous narrow band channels of dissimilar frequencies to achieve high data rate in a multi path fading environment. And all these sub carriers are considered to be orthogonal to each other. As the number of sub carriers is increased there is no guarantee of sustained orthogonality, i.e. at some point the carriers are not
independent to each other, and hence where the orthogonality can be loosed which leads to interference and also owing to the synchronization between transmitter and receiver local oscillator, it causes interference known as Inter Carrier Interference (ICI). The systems uses MIMO-OFDM will suffer with the effects of ICI and Carrier Frequency Offset (CFO) “ε”. However these affect the power leakage in the midst of sub carriers, consequently degrading the system performance. In this paper a new approach is proposed in order to reduce the ICI caused in WiMAX and improve the system performance. In this scheme at the transmitter side the modulated data and a few predefined pilot symbols are mapped onto the non
neighboring sub carriers with weighting coefficients of +1 and -1. With the aid of pilot symbols the frequency offset is exactly estimated by using Maximum Likelihood Estimation (MLE) and hence can be minimized. At demodulation stage the received signals are linearly combined along with their weighted
coefficients and pilot symbols, called as Pilot Aided Self Cancellation Method (PASCS). And also to realize the various wireless environments the simulations are carried out on Stanford University Interim (SUI) channels. The simulation results shows that by incorporating this method into WiMAX systems it performs better when the Line Of Sight (LOS) component is present in the transmission and also it improves the Bit Error Rate (BER) and Carrier to Interference Ratio (CIR). The CIR can be improved 20 dB. In this paper the effectiveness of PASCS scheme is compared with the Self Cancellation Method (SCM). It provides accurate estimation of frequency offset and when residual CFO is less significant the ICI can be diminished successfully.
ANALYSIS OF ROBUST MILTIUSER DETECTION TECHNIQUE FOR COMMUNICATION SYSTEMIJARIIE JOURNAL
This document summarizes a research paper that analyzes a robust multiuser detection technique called Group Based Successive Interference Cancellation (GSIC) for communication systems. GSIC is a nonlinear approach that applies successive interference cancellation processing to groups of signals based on their strength, rather than individual signals. This technique aims to improve the bit error rate compared to conventional successive interference cancellation schemes by reducing delay and increasing signal-to-noise ratio. The document provides background on multiuser detection and CDMA systems, describes the GSIC technique and methodology used to analyze it through MATLAB simulations, and reviews related work on successive interference cancellation approaches.
An Approach to Improve the Quality of Service in OFDMA Relay Networks via Re-...iosrjce
With the next-generation cellular networks making a transition toward smaller cells, two-hop
orthogonal frequency-division multiple access (OFDMA) relay networks have become a dominant, mandatory
component in the 4G standards (WiMAX802.16j, 3GPP LTE-Adv.). Here we are using the multicasting strategy
Given the growing importance of multimedia broadcast and multicast services (MBMS) in 4G networks, the
latter forms the focus of this project. The main aim of this project is to improve the performance of the OFDMA
based relay networks. The OFDMA transmission Scheme is a widely accepted scheme for improving the quality
and speed of communication over the 4G cellular network. There are two different models designed for OFDMA
relay networks .Distributed (DP) and Contiguous (CP) permutations. We are checking the performance of two
algorithms The linear programming algorithm and the greedy algorithm by using two models of OFDMA for
multicast scheduling and after performance evaluation we select the best model and the algorithm for
transmission. We further improve the throughput via retransmission of lost packets during data transfer over the
specified network. We can detect the packet loss by packet synchronization technique and a request will be sent
by the destination for re-sending the lost packets which is called as Re-Transmission.[1]
This document discusses and compares wireless communication technologies including OFDMA, SC-FDMA, CDMA, and LTE. It provides an overview of these technologies, how they have evolved over time, and their performance. Key points discussed include how LTE uses OFDMA for downlinks and SC-FDMA for uplinks, the benefits of MIMO techniques for improving spectral efficiency, and methods for estimating signal-to-noise ratio to enable adaptive modulation schemes. The document also includes figures comparing parameters of various wireless standards.
Multi User Detection in CDMA System Using Linear and Non Linear DetectorWaqas Tariq
DS-Code division multiple access is considered as the third generation of cellular mobile used in interim standard 95(IS-95) [1]and it is currently being standardized for universal mobile telecommunication systems (UMTS). CDMA offers attractive features, such as frequency reuse, soft handoff, increased capacity, and multipath combating. In a CDMA system, several users simultaneously transmit information over a common channel using pre-assigned codes. The conventional single user detector consists of a bank of filters matched to the spreading codes. This detector suffers from two problems. First, multiple access interference (MAI) produced by the other co-channel users is a significant limitation to the capacity of this detector. The second problem is the near-far effect which occurs when the relative received power of interfering signals becomes larger. A potential solution is multi-user detection which exploits the information of signals of interfering users. In the present study performance of various linear detectors like matched filter detector, MMSE detector, and adaptive LMS detector are studied. These are the linear detectors that operate linearly on the received signal statistics and are suboptimal detectors. The matched filter bank is the conventional detector and offers the simplest way of demodulating CDMA signals .The detector resulting from the MMSE (minimum mean square error) criterion shows better performance over the conventional one for low SNR value. Adaptive LMS is employed to enhance the BER performance in MUD application.Several factors motivated the research to apply neural network as multi-user detector. NN are nonlinear classifier in addition to being adaptive and computationally efficient. The performance of two layer perceptron neural network using BP learning rule is used for multi-user detection of CDMA signals in AWGN channels. The neural network detectors show improvement of BER in the comparative analysis done in the present work. and offers further research scope for solving multi-user detection problems in CDMA application.
HYPERSPECTRAL IMAGERY CLASSIFICATION USING TECHNOLOGIES OF COMPUTATIONAL INTE...IAEME Publication
Texture information is exploited for classification of HSI (Hyperspectral Imagery) at high spatial resolution. For this purpose, framework employs to LBP (Local Binary Pattern) to extract local image features such as edges, corners & spots. After the extraction of LBP feature two levels of fusions are applied along with Gabor feature & spectral feature, i.e. Feature level fusion & Decision level fusion. In Feature level fusion multiple features are concurred before pattern classification. While in decision level fusion, it works on probability output of each individual classification pipeline combines the distinct decisions into final one. Decision level fusion consists of either hard fusion, soft fusion method. In hard fusion we consider majority part & in soft fusion linear logarithmic opinion pool at probability level (LOGP). In addition to this, extreme learning machine (ELM) classifier is included which is more efficient than support vector machine (SVM), used to provide probability classification output. It has simple structure with one hidden layer & one linear output layer. ELM trained much faster than SVM.
The document discusses various literature on OFDM and MC-CDMA techniques. It summarizes 17 research papers on topics like using wavelet packets instead of Fourier transform in MC-CDMA to improve bandwidth efficiency and reduce interference. It also discusses using techniques like DWT, Radon transform, and antenna diversity with MC-CDMA and comparing the BER performance of different approaches in various channel conditions like AWGN, Rayleigh fading and frequency selective fading channels. The rationale given is that replacing Fourier transform with wavelet packets in MC-CDMA can eliminate the need for cyclic prefix and improve spectral efficiency.
The document surveys 17 literature sources on multi-carrier modulation techniques like OFDM and MC-CDMA. Several sources propose using wavelet transforms instead of Fourier transforms to improve bandwidth efficiency and reduce interference for MC-CDMA systems. Simulation results from the literature show that wavelet packet based MC-CDMA can outperform FFT based MC-CDMA in terms of lower bit error rates, especially in frequency selective fading channels. The rationale given is that wavelet transforms eliminate the need for cyclic prefixes, thereby improving spectral efficiency over traditional MC-CDMA schemes.
ESTIMATION AND COMPENSATION OF INTER CARRIER INTERFERENCE IN WIMAX PHYSICAL L...ijngnjournal
WiMAX is Wireless Interoperability for Microwave Access has emerged as a promising solution for transmission of higher data rates for fixed and mobile applications. IEEE 802.16d and e are the standards proposed by WiMAX group for fixed and mobile. As the wireless channel have so many limitation Such as Multipath, Doppler spread, Delay spread and Line Of Sight (LOS)/Non Line Of Sight (NLOS) components. To attain higher data rates the Multi Carrier System with Multiple Input and Multiple Output (MIMO) is incorporated in the WiMAX. The Orthogonal Frequency Division Multiplexing (OFDM) is a multi carrier technique used with the WiMAX systems. In OFDM the available spectrum is split into numerous narrow band channels of dissimilar frequencies to achieve high data rate in a multi path fading environment. And all these sub carriers are considered to be orthogonal to each other. As the number of sub carriers is increased there is no guarantee of sustained orthogonality, i.e. at some point the carriers are not
independent to each other, and hence where the orthogonality can be loosed which leads to interference and also owing to the synchronization between transmitter and receiver local oscillator, it causes interference known as Inter Carrier Interference (ICI). The systems uses MIMO-OFDM will suffer with the effects of ICI and Carrier Frequency Offset (CFO) “ε”. However these affect the power leakage in the midst of sub carriers, consequently degrading the system performance. In this paper a new approach is proposed in order to reduce the ICI caused in WiMAX and improve the system performance. In this scheme at the transmitter side the modulated data and a few predefined pilot symbols are mapped onto the non
neighboring sub carriers with weighting coefficients of +1 and -1. With the aid of pilot symbols the frequency offset is exactly estimated by using Maximum Likelihood Estimation (MLE) and hence can be minimized. At demodulation stage the received signals are linearly combined along with their weighted
coefficients and pilot symbols, called as Pilot Aided Self Cancellation Method (PASCS). And also to realize the various wireless environments the simulations are carried out on Stanford University Interim (SUI) channels. The simulation results shows that by incorporating this method into WiMAX systems it performs better when the Line Of Sight (LOS) component is present in the transmission and also it improves the Bit Error Rate (BER) and Carrier to Interference Ratio (CIR). The CIR can be improved 20 dB. In this paper the effectiveness of PASCS scheme is compared with the Self Cancellation Method (SCM). It provides accurate estimation of frequency offset and when residual CFO is less significant the ICI can be diminished successfully.
ANALYSIS OF ROBUST MILTIUSER DETECTION TECHNIQUE FOR COMMUNICATION SYSTEMIJARIIE JOURNAL
This document summarizes a research paper that analyzes a robust multiuser detection technique called Group Based Successive Interference Cancellation (GSIC) for communication systems. GSIC is a nonlinear approach that applies successive interference cancellation processing to groups of signals based on their strength, rather than individual signals. This technique aims to improve the bit error rate compared to conventional successive interference cancellation schemes by reducing delay and increasing signal-to-noise ratio. The document provides background on multiuser detection and CDMA systems, describes the GSIC technique and methodology used to analyze it through MATLAB simulations, and reviews related work on successive interference cancellation approaches.
An Approach to Improve the Quality of Service in OFDMA Relay Networks via Re-...iosrjce
With the next-generation cellular networks making a transition toward smaller cells, two-hop
orthogonal frequency-division multiple access (OFDMA) relay networks have become a dominant, mandatory
component in the 4G standards (WiMAX802.16j, 3GPP LTE-Adv.). Here we are using the multicasting strategy
Given the growing importance of multimedia broadcast and multicast services (MBMS) in 4G networks, the
latter forms the focus of this project. The main aim of this project is to improve the performance of the OFDMA
based relay networks. The OFDMA transmission Scheme is a widely accepted scheme for improving the quality
and speed of communication over the 4G cellular network. There are two different models designed for OFDMA
relay networks .Distributed (DP) and Contiguous (CP) permutations. We are checking the performance of two
algorithms The linear programming algorithm and the greedy algorithm by using two models of OFDMA for
multicast scheduling and after performance evaluation we select the best model and the algorithm for
transmission. We further improve the throughput via retransmission of lost packets during data transfer over the
specified network. We can detect the packet loss by packet synchronization technique and a request will be sent
by the destination for re-sending the lost packets which is called as Re-Transmission.[1]
Iaetsd comparative study mimo ofdm, cdma-sdmaIaetsd Iaetsd
This document compares and contrasts MIMO OFDM, CDMA-SDMA, and multi-user detection techniques for wireless communication systems. It discusses how MIMO OFDM can achieve high data rates with frequency and antenna diversity. Space division multiple access (SDMA) is introduced as an application of MIMO that improves spectral efficiency by multiplexing signals based on spatial signatures. The document also examines multi-user detection methods like linear detection, minimum mean square error, and successive interference cancellation that are needed for robust SDMA performance as the number of users increases.
Oblivious Cooperative Communication in Cognitive Radio Networks_FinalProjectMicheal Fisher
This document discusses a system for cooperative communication in cognitive radio networks using multiple secondary users. It begins with introducing cognitive radio networks and cooperative communication schemes. It then proposes a system where secondary users cooperatively help primary users' communication through a cooperative relay MIMO scheme. Key steps of the scheme involve secondary users receiving and saving primary users' data, transmitting the data locally between secondary users, and transmitting the data simultaneously to the intended primary user. Formulas are derived to calculate the maximum distance secondary users can be from primary users while maintaining communication quality metrics like error rate.
Dynamic Sub-Channel Allocation in Multiuser OFDM Systems to Achieve Variable ...IDES Editor
This document summarizes a research paper that proposes a dynamic sub-channel allocation algorithm in multiuser OFDM systems to achieve variable data rates. It investigates allocating frequency sub-channels adaptively among users to take advantage of channel diversity and maximize capacity while maintaining proportional fairness. The algorithm first allocates sub-channels assuming equal power distribution, then optimizes power allocation. Simulation results show the algorithm efficiently distributes capacity according to proportional rate constraints.
This document provides a survey of cooperative communication techniques for 4G LTE wireless networks. It discusses how cooperative communication can provide benefits like increased capacity, transmission reliability, and spatial diversity without needing multiple antennas at both transmitter and receiver. The document reviews various cooperative relaying approaches including amplify-and-forward and decode-and-forward. It also compares techniques like DF cooperative relaying, DNF-TPSR, STBC-NOMA, and discusses issues like spectral efficiency that future research could focus on improving cooperative communication further.
MULTI USER DETECTOR IN CDMA USING ELLIPTIC CURVE CRYPTOGRAPHYVLSICS Design
Code division multiple access (CDMA) is used in various radio communication techniques due to its advantages. In CDMA one of the most important processes is multi user detection (MUD). There are numerous methods for MUD in CDMA, but in most of the methods, they identify the exact user but the interference signal is high. One of the methods used for MUD in CDM A is elliptic curve cryptography (ECC). Normally, the multi user detector in CDMA using elliptic curve cryptography is performed by using one prime field. In ECC method the exact user is identified and also interference signal reduces comparing with other techniques. To reduce the interference signal to very low, here propose a new technique for MUD in CDMA using ECC. The proposed technique uses multiple prime numbers for key generation. By generating key using different prime numbers using ECC, the bit error rate was very low. The results shows the performance of the proposed for reduce in bit error rate for MUD in CDMA.
This document presents a master's thesis that compares the non-orthogonal waveforms FBMC and UFMC to OFDM for 5G. The thesis was completed at the University of Applied Sciences Rosenheim in Germany. It includes simulations in MATLAB to characterize the waveforms using metrics like error vector magnitude, power spectral density, and complementary cumulative distribution function. FBMC uses a prototype filter and polyphase network to eliminate interference between subcarriers while UFMC filters blocks of subcarriers. Both waveforms are compared to OFDM and simulated over an AWGN channel with channel estimation techniques. The thesis provides background on the waveforms and details of the MATLAB simulations and analysis to meet the objectives of characterizing and comparing the 5G candidate waveforms
This document describes the simulation of an OFDM system using MATLAB. It discusses how OFDM works and its advantages for wireless communications. The simulator allows analyzing the performance of BPSK, QPSK, and QAM modulation under Rayleigh fading and multipath channels. It measures bit error rate as a function of signal to noise ratio. The GUI interface facilitates changing parameters and visualizing the transmitted and received OFDM frames, spectra, and constellations. Simulation results demonstrate the variation in performance between modulation techniques in different channel conditions.
An investigation-on-efficient-spreading-codes-for-transmitter-based-technique...Cemal Ardil
This document summarizes research on efficient spreading codes for transmitter-based techniques to mitigate interference in time division duplex code division multiple access (TDD/CDMA) downlink systems. It investigates bitwise and blockwise multiuser transmission schemes that transfer complexity to the transmitter. Different spreading codes are evaluated based on correlation properties to determine suitability for techniques like precoding, pre-rake, and rake diversity. Performance is measured by bit error rate with varying numbers of users to identify the most efficient codes for interference mitigation.
PERFORMANCE ANALYSIS OF BARKER CODE BASED ON THEIR CORRELATION PROPERTY IN MU...ijistjournal
Spread-spectrum communication, with its inherent interference attenuation capability, has over the years become an increasingly popular technique for use in many different systems. They have very beneficial and tempting features, like Antijam, Security, and Multiple accesses. This thesis basically deals with the pseudo codes used in spread spectrum communication system. The cross-correlation and auto-correlation properties of the long Barker Code are analyzed. It has been seen that the length of the code, autocorrelation and cross-correlation properties can help us to determine the best suitable code for any particular communication environment. We have tried to find out the code with suitable auto-correlation properties along with low cross-correlation values. Barker code has good auto-correlation properties and we have found the pairs with the low cross- correlation so that they can be used in multi-user environment.
Comparative Performance Assessment of V-Blast Encoded 8×8 MIMO MC-CDMA Wirele...pijans
The bit error rate performance of a V-Blast encoded 8x8 MIMO MC-CDMA wireless communication system
for different signal detection (MMSE and ZF) and digital modulation (BPSK, QPSK, DPSK, and 4QAM)
schemes for grayscale image transmission has been investigated in this paper. The proposed wireless system
employ ½-rated Convolution and cyclic redundancy check (CRC) channel encoding over the AWGN
channel and Walsh Hadamard code as an orthogonal spread code. The present Matlab based simulation study
demonstrates that the V-Blast encoded 8×8 MIMO MC-CDMA wireless system with the employment of 1⁄2-
rated convolution and cyclic redundancy check (CRC) channel encoding strategies shows good performance
utilizing BPSK digital modulation and ZF signal detection scheme in grayscale image transmission
VHDL Implementation of FPGA Based OFDM Modem for Wireless ApplicationsEditor IJCATR
This document describes the VHDL implementation of an FPGA-based OFDM modem for wireless applications. It discusses Orthogonal Frequency Division Multiplexing (OFDM) and how it can be used for high-speed wireless communications. The document outlines the basic blocks of an OFDM modulator and demodulator system, including QAM/PSK modulation, serial to parallel conversion, inverse fast Fourier transform (IFFT), and how these can be implemented using VHDL on an FPGA for applications such as software defined radio. It provides a block diagram of the OFDM modem and discusses the advantages of implementing the design using a field programmable gate array.
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
Simulation of Few Mode Fiber Communication System Using Adaptive Recursive le...rahulmonikasharma
The document summarizes research on simulation of few mode fiber communication systems using adaptive algorithms. It discusses using the recursive least squares (RLS) algorithm to improve convergence speed but with increased complexity compared to frequency domain least mean square (FD-LMS) algorithms. The FD-LMS algorithm is used as a reference. A step size controller is also proposed to improve convergence behavior. Previous studies on adaptive frequency domain equalization schemes and use of normalized frequency domain adaptive filters to increase convergence speed over long transmission distances are also summarized.
DESIGN OF A COMPACT CIRCULAR MICROSTRIP PATCH ANTENNA FOR WLAN APPLICATIONS pijans
This paper presents the design of a compact circular microstrip patch antenna for WLAN applications which covers the band 5.15 to 5.825 GHz. The antenna is designed using 1.4mm thick FR-4 (lossy)substrate with relative permittivity 4.4 and a microstrip line feed is used. The radius of the circular patch is chosen as 7.62mm. To reduce the size and enhance the performance of the proposed antenna, a circular slot is loaded on circular patch and a square slot is etched on the ground plane of dimension 30mm×30mm. Design of the antenna is carried out using CST Microsoft Studio Sonimulation Software. The proposed antenna resonates at 5.5 GHz with a wider bandwidth of 702 MHz and it provides low return loss of -31.58 dB, good gain of 3.23 dB and directivity of 4.28 dBi and high efficiency of around 79% against the resonance frequency. The geometry of the proposed circular antenna with reduced size and its various performance parameters such as return loss, bandwidth, VSWR, gain, directivity, efficiency and radiation pattern plots are presented and discussed.
A small vessel detection using a co-located multi-frequency FMCW MIMO radar IJECEIAES
Small vessels detection is a known issue due to its low radar cross section (RCS). An existing shore-based vessel tracking radar is for long-distance commercial vessels detection. Meanwhile, a vessel-mounted radar system known for its reliability has a limitation due to its single radar coverage. The paper presented a co-located frequency modulated continuous waveform (FMCW) maritime radar for small vessel detection utilising a multiple-input multiple-output (MIMO) configuration. The radar behaviour is numerically simulated for detecting a Swerling 1 target which resembles small maritime’s vessels. The simulated MIMO configuration comprised two transmitting and receiving nodes. The proposal is to utilize a multi-frequency FMCW MIMO configuration in a maritime environment by applying the spectrum averaging (SA) to fuse MIMO received signals for range and velocity estimation. The analysis was summarised and displayed in terms of estimation error performance, probability of error and average error. The simulation outcomes an improvement of 2.2 dB for a static target, and 0.1 dB for a moving target, in resulting the 20% probability of range error with the MIMO setup. A moving vessel's effect was observed to degrade the range error estimation performance between 0.6 to 2.7 dB. Meanwhile, the proposed method was proven to improve the 20% probability of velocity error by 1.75 dB. The impact of multi-frequency MIMO was also observed to produce better average error performance.
This document discusses an iterative MMSE-PIC detection algorithm for MIMO-OFDM systems. It begins with an introduction to MIMO and OFDM technologies and how their combination can provide high spectrum efficiency and diversity gain against fading channels. It then describes the iterative MMSE-PIC detection algorithm, which utilizes parallel interference cancellation and iteration to improve detection performance compared to other detectors like ZF and MMSE in noisy environments. The document provides details on the system model and MIMO techniques like spatial multiplexing and diversity schemes before introducing the proposed iterative MMSE-PIC detection algorithm for MIMO-OFDM systems.
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
Effect of Interleaved FEC Code on Wavelet Based MC-CDMA System with Alamouti ...IJCSEIT Journal
In this paper, the impact of Forward Error Correction (FEC) code namely Trellis code with interleaver on
the performance of wavelet based MC-CDMA wireless communication system with the implementation of
Alamouti antenna diversity scheme has been investigated in terms of Bit Error Rate (BER) as a function of
Signal-to-Noise Ratio (SNR) per bit. Simulation of the system under proposed study has been done in M-ary
modulation schemes (MPSK, MQAM and DPSK) over AWGN and Rayleigh fading channel incorporating
Walsh Hadamard code as orthogonal spreading code to discriminate the message signal for individual
user. It is observed via computer simulation that the performance of the interleaved coded based proposed
system outperforms than that of the uncoded system in all modulation schemes over Rayleigh fading
channel.
This document summarizes a research paper on CORMAN, a novel cooperative opportunistic routing scheme for mobile ad hoc networks. CORMAN utilizes the broadcasting nature of wireless transmissions to opportunistically select forwarders that are better able to receive packets. It uses a lightweight proactive source routing protocol to provide each node with complete routing information. When packets are forwarded, intermediate nodes can update the forwarder list if they have a different view of the optimal route due to network changes from mobility. CORMAN also allows non-listed nodes to retransmit packets if it improves delivery. Simulation results showed CORMAN provides significantly better performance than AODV in mobile network scenarios.
COMPARATIVE PERFORMANCE ASSESSMENT OF VBLAST ENCODED 8×8 MIMO MC-CDMA WIRELES...pijans
The bit error rate performance of a V-Blast encoded 8x8 MIMO MC-CDMA wireless communication system
for different signal detection (MMSE and ZF) and digital modulation (BPSK, QPSK, DPSK, and 4QAM)
schemes for grayscale image transmission has been investigated in this paper. The proposed wireless system
employ ½-rated Convolution and cyclic redundancy check (CRC) channel encoding over the AWGN channel
and Walsh Hadamard code as an orthogonal spread code. The present Matlab based simulation study
demonstrates that the V-Blast encoded 8×8 MIMO MC-CDMA wireless system with the employment of 1⁄2-
rated convolution and cyclic redundancy check (CRC) channel encoding strategies shows good performance
utilizing BPSK digital modulation and ZF signal detection scheme in grayscale image transmission
Solving Transportation Problems with Hexagonal Fuzzy Numbers Using Best Candi...IJERA Editor
In this paper, we introduce a Fuzzy Transportation Problem (FTP) in which the values of transportation costs are
represented as hexagonal fuzzy numbers. We use the Best candidate method to solve the FTP. The Centroid
ranking technique is used to obtain the optimal solution.
The Role Played by the Advance Maintenance Practice in manufacturing pеrforma...IJERA Editor
It is not obvious how firms should mеasurе thеir manufacturing pеrformancеs. Various approachеs, most of
thеm with a largе numbеr of mеasurеs on diffеrеnt hiеrarchical lеvеls, еxist. Many of thе mеasurеs usеd arе
considеrеd obsolеtе and inconsistеnt for various rеasons. Thе usеfulnеss of most cost accounting systеms,
individual mеasurеs as wеll as morе comprеhеnsivе activity-basеd costing systеms, arе frеquеntly quеstionеd
sincе thеy do not covеr manufacturing pеrformancеs rеlativе to thе compеtitivе capabilitiеs (е.g. Dixon еt al.,
1990, Whitе, 1996). Anothеr sеrious problеm with most pеrformancе mеasurеmеnt systеms usеd in firms is that
thеy oftеn includе too many diffеrеnt mеasurеs, which makеs it difficult to undеrstand thе "big picturе" (Kееgan
еt al., 1989).
Iaetsd comparative study mimo ofdm, cdma-sdmaIaetsd Iaetsd
This document compares and contrasts MIMO OFDM, CDMA-SDMA, and multi-user detection techniques for wireless communication systems. It discusses how MIMO OFDM can achieve high data rates with frequency and antenna diversity. Space division multiple access (SDMA) is introduced as an application of MIMO that improves spectral efficiency by multiplexing signals based on spatial signatures. The document also examines multi-user detection methods like linear detection, minimum mean square error, and successive interference cancellation that are needed for robust SDMA performance as the number of users increases.
Oblivious Cooperative Communication in Cognitive Radio Networks_FinalProjectMicheal Fisher
This document discusses a system for cooperative communication in cognitive radio networks using multiple secondary users. It begins with introducing cognitive radio networks and cooperative communication schemes. It then proposes a system where secondary users cooperatively help primary users' communication through a cooperative relay MIMO scheme. Key steps of the scheme involve secondary users receiving and saving primary users' data, transmitting the data locally between secondary users, and transmitting the data simultaneously to the intended primary user. Formulas are derived to calculate the maximum distance secondary users can be from primary users while maintaining communication quality metrics like error rate.
Dynamic Sub-Channel Allocation in Multiuser OFDM Systems to Achieve Variable ...IDES Editor
This document summarizes a research paper that proposes a dynamic sub-channel allocation algorithm in multiuser OFDM systems to achieve variable data rates. It investigates allocating frequency sub-channels adaptively among users to take advantage of channel diversity and maximize capacity while maintaining proportional fairness. The algorithm first allocates sub-channels assuming equal power distribution, then optimizes power allocation. Simulation results show the algorithm efficiently distributes capacity according to proportional rate constraints.
This document provides a survey of cooperative communication techniques for 4G LTE wireless networks. It discusses how cooperative communication can provide benefits like increased capacity, transmission reliability, and spatial diversity without needing multiple antennas at both transmitter and receiver. The document reviews various cooperative relaying approaches including amplify-and-forward and decode-and-forward. It also compares techniques like DF cooperative relaying, DNF-TPSR, STBC-NOMA, and discusses issues like spectral efficiency that future research could focus on improving cooperative communication further.
MULTI USER DETECTOR IN CDMA USING ELLIPTIC CURVE CRYPTOGRAPHYVLSICS Design
Code division multiple access (CDMA) is used in various radio communication techniques due to its advantages. In CDMA one of the most important processes is multi user detection (MUD). There are numerous methods for MUD in CDMA, but in most of the methods, they identify the exact user but the interference signal is high. One of the methods used for MUD in CDM A is elliptic curve cryptography (ECC). Normally, the multi user detector in CDMA using elliptic curve cryptography is performed by using one prime field. In ECC method the exact user is identified and also interference signal reduces comparing with other techniques. To reduce the interference signal to very low, here propose a new technique for MUD in CDMA using ECC. The proposed technique uses multiple prime numbers for key generation. By generating key using different prime numbers using ECC, the bit error rate was very low. The results shows the performance of the proposed for reduce in bit error rate for MUD in CDMA.
This document presents a master's thesis that compares the non-orthogonal waveforms FBMC and UFMC to OFDM for 5G. The thesis was completed at the University of Applied Sciences Rosenheim in Germany. It includes simulations in MATLAB to characterize the waveforms using metrics like error vector magnitude, power spectral density, and complementary cumulative distribution function. FBMC uses a prototype filter and polyphase network to eliminate interference between subcarriers while UFMC filters blocks of subcarriers. Both waveforms are compared to OFDM and simulated over an AWGN channel with channel estimation techniques. The thesis provides background on the waveforms and details of the MATLAB simulations and analysis to meet the objectives of characterizing and comparing the 5G candidate waveforms
This document describes the simulation of an OFDM system using MATLAB. It discusses how OFDM works and its advantages for wireless communications. The simulator allows analyzing the performance of BPSK, QPSK, and QAM modulation under Rayleigh fading and multipath channels. It measures bit error rate as a function of signal to noise ratio. The GUI interface facilitates changing parameters and visualizing the transmitted and received OFDM frames, spectra, and constellations. Simulation results demonstrate the variation in performance between modulation techniques in different channel conditions.
An investigation-on-efficient-spreading-codes-for-transmitter-based-technique...Cemal Ardil
This document summarizes research on efficient spreading codes for transmitter-based techniques to mitigate interference in time division duplex code division multiple access (TDD/CDMA) downlink systems. It investigates bitwise and blockwise multiuser transmission schemes that transfer complexity to the transmitter. Different spreading codes are evaluated based on correlation properties to determine suitability for techniques like precoding, pre-rake, and rake diversity. Performance is measured by bit error rate with varying numbers of users to identify the most efficient codes for interference mitigation.
PERFORMANCE ANALYSIS OF BARKER CODE BASED ON THEIR CORRELATION PROPERTY IN MU...ijistjournal
Spread-spectrum communication, with its inherent interference attenuation capability, has over the years become an increasingly popular technique for use in many different systems. They have very beneficial and tempting features, like Antijam, Security, and Multiple accesses. This thesis basically deals with the pseudo codes used in spread spectrum communication system. The cross-correlation and auto-correlation properties of the long Barker Code are analyzed. It has been seen that the length of the code, autocorrelation and cross-correlation properties can help us to determine the best suitable code for any particular communication environment. We have tried to find out the code with suitable auto-correlation properties along with low cross-correlation values. Barker code has good auto-correlation properties and we have found the pairs with the low cross- correlation so that they can be used in multi-user environment.
Comparative Performance Assessment of V-Blast Encoded 8×8 MIMO MC-CDMA Wirele...pijans
The bit error rate performance of a V-Blast encoded 8x8 MIMO MC-CDMA wireless communication system
for different signal detection (MMSE and ZF) and digital modulation (BPSK, QPSK, DPSK, and 4QAM)
schemes for grayscale image transmission has been investigated in this paper. The proposed wireless system
employ ½-rated Convolution and cyclic redundancy check (CRC) channel encoding over the AWGN
channel and Walsh Hadamard code as an orthogonal spread code. The present Matlab based simulation study
demonstrates that the V-Blast encoded 8×8 MIMO MC-CDMA wireless system with the employment of 1⁄2-
rated convolution and cyclic redundancy check (CRC) channel encoding strategies shows good performance
utilizing BPSK digital modulation and ZF signal detection scheme in grayscale image transmission
VHDL Implementation of FPGA Based OFDM Modem for Wireless ApplicationsEditor IJCATR
This document describes the VHDL implementation of an FPGA-based OFDM modem for wireless applications. It discusses Orthogonal Frequency Division Multiplexing (OFDM) and how it can be used for high-speed wireless communications. The document outlines the basic blocks of an OFDM modulator and demodulator system, including QAM/PSK modulation, serial to parallel conversion, inverse fast Fourier transform (IFFT), and how these can be implemented using VHDL on an FPGA for applications such as software defined radio. It provides a block diagram of the OFDM modem and discusses the advantages of implementing the design using a field programmable gate array.
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
Simulation of Few Mode Fiber Communication System Using Adaptive Recursive le...rahulmonikasharma
The document summarizes research on simulation of few mode fiber communication systems using adaptive algorithms. It discusses using the recursive least squares (RLS) algorithm to improve convergence speed but with increased complexity compared to frequency domain least mean square (FD-LMS) algorithms. The FD-LMS algorithm is used as a reference. A step size controller is also proposed to improve convergence behavior. Previous studies on adaptive frequency domain equalization schemes and use of normalized frequency domain adaptive filters to increase convergence speed over long transmission distances are also summarized.
DESIGN OF A COMPACT CIRCULAR MICROSTRIP PATCH ANTENNA FOR WLAN APPLICATIONS pijans
This paper presents the design of a compact circular microstrip patch antenna for WLAN applications which covers the band 5.15 to 5.825 GHz. The antenna is designed using 1.4mm thick FR-4 (lossy)substrate with relative permittivity 4.4 and a microstrip line feed is used. The radius of the circular patch is chosen as 7.62mm. To reduce the size and enhance the performance of the proposed antenna, a circular slot is loaded on circular patch and a square slot is etched on the ground plane of dimension 30mm×30mm. Design of the antenna is carried out using CST Microsoft Studio Sonimulation Software. The proposed antenna resonates at 5.5 GHz with a wider bandwidth of 702 MHz and it provides low return loss of -31.58 dB, good gain of 3.23 dB and directivity of 4.28 dBi and high efficiency of around 79% against the resonance frequency. The geometry of the proposed circular antenna with reduced size and its various performance parameters such as return loss, bandwidth, VSWR, gain, directivity, efficiency and radiation pattern plots are presented and discussed.
A small vessel detection using a co-located multi-frequency FMCW MIMO radar IJECEIAES
Small vessels detection is a known issue due to its low radar cross section (RCS). An existing shore-based vessel tracking radar is for long-distance commercial vessels detection. Meanwhile, a vessel-mounted radar system known for its reliability has a limitation due to its single radar coverage. The paper presented a co-located frequency modulated continuous waveform (FMCW) maritime radar for small vessel detection utilising a multiple-input multiple-output (MIMO) configuration. The radar behaviour is numerically simulated for detecting a Swerling 1 target which resembles small maritime’s vessels. The simulated MIMO configuration comprised two transmitting and receiving nodes. The proposal is to utilize a multi-frequency FMCW MIMO configuration in a maritime environment by applying the spectrum averaging (SA) to fuse MIMO received signals for range and velocity estimation. The analysis was summarised and displayed in terms of estimation error performance, probability of error and average error. The simulation outcomes an improvement of 2.2 dB for a static target, and 0.1 dB for a moving target, in resulting the 20% probability of range error with the MIMO setup. A moving vessel's effect was observed to degrade the range error estimation performance between 0.6 to 2.7 dB. Meanwhile, the proposed method was proven to improve the 20% probability of velocity error by 1.75 dB. The impact of multi-frequency MIMO was also observed to produce better average error performance.
This document discusses an iterative MMSE-PIC detection algorithm for MIMO-OFDM systems. It begins with an introduction to MIMO and OFDM technologies and how their combination can provide high spectrum efficiency and diversity gain against fading channels. It then describes the iterative MMSE-PIC detection algorithm, which utilizes parallel interference cancellation and iteration to improve detection performance compared to other detectors like ZF and MMSE in noisy environments. The document provides details on the system model and MIMO techniques like spatial multiplexing and diversity schemes before introducing the proposed iterative MMSE-PIC detection algorithm for MIMO-OFDM systems.
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
Effect of Interleaved FEC Code on Wavelet Based MC-CDMA System with Alamouti ...IJCSEIT Journal
In this paper, the impact of Forward Error Correction (FEC) code namely Trellis code with interleaver on
the performance of wavelet based MC-CDMA wireless communication system with the implementation of
Alamouti antenna diversity scheme has been investigated in terms of Bit Error Rate (BER) as a function of
Signal-to-Noise Ratio (SNR) per bit. Simulation of the system under proposed study has been done in M-ary
modulation schemes (MPSK, MQAM and DPSK) over AWGN and Rayleigh fading channel incorporating
Walsh Hadamard code as orthogonal spreading code to discriminate the message signal for individual
user. It is observed via computer simulation that the performance of the interleaved coded based proposed
system outperforms than that of the uncoded system in all modulation schemes over Rayleigh fading
channel.
This document summarizes a research paper on CORMAN, a novel cooperative opportunistic routing scheme for mobile ad hoc networks. CORMAN utilizes the broadcasting nature of wireless transmissions to opportunistically select forwarders that are better able to receive packets. It uses a lightweight proactive source routing protocol to provide each node with complete routing information. When packets are forwarded, intermediate nodes can update the forwarder list if they have a different view of the optimal route due to network changes from mobility. CORMAN also allows non-listed nodes to retransmit packets if it improves delivery. Simulation results showed CORMAN provides significantly better performance than AODV in mobile network scenarios.
COMPARATIVE PERFORMANCE ASSESSMENT OF VBLAST ENCODED 8×8 MIMO MC-CDMA WIRELES...pijans
The bit error rate performance of a V-Blast encoded 8x8 MIMO MC-CDMA wireless communication system
for different signal detection (MMSE and ZF) and digital modulation (BPSK, QPSK, DPSK, and 4QAM)
schemes for grayscale image transmission has been investigated in this paper. The proposed wireless system
employ ½-rated Convolution and cyclic redundancy check (CRC) channel encoding over the AWGN channel
and Walsh Hadamard code as an orthogonal spread code. The present Matlab based simulation study
demonstrates that the V-Blast encoded 8×8 MIMO MC-CDMA wireless system with the employment of 1⁄2-
rated convolution and cyclic redundancy check (CRC) channel encoding strategies shows good performance
utilizing BPSK digital modulation and ZF signal detection scheme in grayscale image transmission
Solving Transportation Problems with Hexagonal Fuzzy Numbers Using Best Candi...IJERA Editor
In this paper, we introduce a Fuzzy Transportation Problem (FTP) in which the values of transportation costs are
represented as hexagonal fuzzy numbers. We use the Best candidate method to solve the FTP. The Centroid
ranking technique is used to obtain the optimal solution.
The Role Played by the Advance Maintenance Practice in manufacturing pеrforma...IJERA Editor
It is not obvious how firms should mеasurе thеir manufacturing pеrformancеs. Various approachеs, most of
thеm with a largе numbеr of mеasurеs on diffеrеnt hiеrarchical lеvеls, еxist. Many of thе mеasurеs usеd arе
considеrеd obsolеtе and inconsistеnt for various rеasons. Thе usеfulnеss of most cost accounting systеms,
individual mеasurеs as wеll as morе comprеhеnsivе activity-basеd costing systеms, arе frеquеntly quеstionеd
sincе thеy do not covеr manufacturing pеrformancеs rеlativе to thе compеtitivе capabilitiеs (е.g. Dixon еt al.,
1990, Whitе, 1996). Anothеr sеrious problеm with most pеrformancе mеasurеmеnt systеms usеd in firms is that
thеy oftеn includе too many diffеrеnt mеasurеs, which makеs it difficult to undеrstand thе "big picturе" (Kееgan
еt al., 1989).
Supply Chain Coordination with Buy-back and Wholesale-price Contracts under R...IJERA Editor
In order to increase supply chain total profit, we design a supply chain collaboration mechanism between one
supplier and one retailer. Throughout the paper we present one supplier and one retailer set up with random
demand in a decentralized supply chain. An incentive function on the buy-back cost and wholesale price cost is
presented and scheme through the buy-back contract and wholesale-price contract has been developed to enrich
the retailer take part in the collaboration ways. Furthermore, the paper shows that, how corporation between
buy-back contract and wholesale contract could coordinate the supply chain in both a decentralized and
centralized supply chain. Lastly, we set up numerical analyses and the result shows the implied collaboration
mechanism is not permit the decentralized system to achieve the same performance as the centralized decision
however it allows both members in the supply chain gains profit sharing by setting up the contract parameters.
Weldability of Friction Welding Process for AA2024 Alloy and SS304 Stainless ...IJERA Editor
The objective of this work was to assess the weldability of AA2024 alloy and SS304 stainless steel. The process
parameters were frictional time, frictional pressure, rotational speed and forging pressure. The joints were
evaluated for their strength, bulk deformation, penetration and flange formation employing finite element
analysis software code. For friction welding of AA2024 alloy and SS304 stainless steel, the ratio of forging
pressure / frictional pressure should be optimum for good welding.
Interactive E-Lecture Using Video Annotation in Learning GroupsIJERA Editor
Now day‘s users are interested in distance learning as there is rapid growth in digital data due to day today
development in information as well as computer technology. Also its applications or usage have tremendous
response in market. Peoples are attracted towards interactivity in each thing, we found that for e-learning is a
very interactive way to learn and understand things. Currently, YouTube is the global way of video sharing. It is
having certain limitations such as, it having inactivity in online learning. In online study students expecting
some extra guidelines from given resources. In this project we developed video annotation system for foster
active learning. In this project, we achieved active participation of students. There is certain kind of technologies
that extracts some important keywords from textual information. MOOC‘s model is another technology to solve
interaction problem of users in active learning. It also has limitations that it suffered from the problem of
gamification. Our system is interactive as it provides real-time annotations to the video. In our system user can
give their active participation as they have direct interaction to our system. As part of our contribution in this
project we did SVM analysis to provide recommended videos for end users. SVM is Support Vector Machine
algorithm; it classifies the things according to user interest. So, in our system user can search for video and they
get recommended video list for their study.
Soot Formation in Diesel Engines By Using CfdIJERA Editor
In order to meet the stringent emission standards significant efforts have been imparted to the research and
development of cleaner IC engines. Diesel combustion and the formation of pollutants are directly influenced by
spatial and temporal distribution of the fuel injected. The development and validation of computational fluid
dynamics (CFD) models for diesel engine combustion and emissions is described. The complexity of diesel
combustion requires simulations with many complex interacting sub models in order to have a success in
improving the performance and to reduce the emissions. In the present work an attempt has been made to
develop a multidimensional axe-symmetric model for CI engine combustion and emissions. Later simulations
have been carried out. Commercial validation tool FLUENT was used for simulation. The tool solves basic
governing equations of fluid flow that is continuity, momentum, species transport and energy equation. Using
finite volume method turbulence was modeled by using RNG K-ɛ model. Injection was modeled using La
Grangian approach and reaction was modeled using non premixed combustion which considers the effects of
turbulence and detailed chemical mechanism into account to model the reaction rates. The specific heats were
approximated using piecewise polynomials. Subsequently the simulated results have been validated with the
existing experimental values
Theoretical and experimental spectroscopic analysis by FTIR in the effect of ...IJERA Editor
The development of new fibrous composites with specific properties has attracted a big interest in the
development of new technologies. One of the biggest problems in this area is the improvement of the
fiber/matrix interface to increase the mechanical properties in the final composite. In this work, surface chemical
modifications of the rice husk (by-product of the rice industry) were carried out to achieve a better compatibility
with diverse polymeric matrices. These modifications include the use of three different silanes: 3-
(trimethoxysilyl) propyl methacrylate (TMS), dichlorodimethylsilane (DDS) and trichlorovinylsilane (TVS). The
natural fibers and their changes after each treatment were studied experimentally by Fourier Transformed
Infrared Spectroscopy (FTIR). This experimental spectroscopic information was compared with a theoretical
analysis of molecular vibrations using the HyperChem Release 7.0 software as molecular modeling tool. The
result of this comparison confirmed the chemical modification. It was concluded that the chemical modification
was carried out and after an experimental spectroscopic analysis (FTIR) the molecular vibrations data were agree
with those calculated by theoretical analysis being verified in this way the chemical modification of the rice-husk
fiber surface.
Design of Microcontroller Based Multi-Frequency Ultrasonic Pulser ReceiverIJERA Editor
1) Researchers developed a microcontroller-based multi-frequency ultrasonic pulser receiver system that can generate pulsed radio frequencies of different frequencies as selected from a PC without needing to change oscillators.
2) The system uses an ATMega16 microcontroller to control an oscillator chip that can generate frequencies from 1-10MHz as commanded by the PC. It then generates pulse repetition frequencies to create tone bursts that are amplified and transmitted into samples via a transducer.
3) Received echoes are amplified and processed by the receiver section before being displayed on an oscilloscope. The system was tested on water and ethanol samples and able to measure ultrasonic velocities accurately at different frequencies.
Optimizing Hybrid Wind/Diesel Generator System Using BAT AlgorithmIJERA Editor
Hybrid system comprising of Wind/Diesel generation system for a practical standalone application considers
Wind turbine generators and diesel generator as primary power sources for generating electricity. Battery banks
are considered as a backup power source. The total value of cost is reduced by meeting energy demand required
by the customers. Bat optimization technique is implemented to optimize wind and battery modules. Wind and
battery banks are considered as primary sources and diesel generator as a secondary power source for the system
Transportation Problem with Pentagonal Intuitionistic Fuzzy Numbers Solved Us...IJERA Editor
This paper presents a solution methodology for transportation problem in an intuitionistic fuzzy environment in
which cost are represented by pentagonal intuitionistic fuzzy numbers. Transportation problem is a particular
class of linear programming, which is associated with day to day activities in our real life. It helps in solving
problems on distribution and transportation of resources from one place to another. The objective is to satisfy
the demand at destination from the supply constraints at the minimum transportation cost possible. The problem
is solved using a ranking technique called Accuracy function for pentagonal intuitionistic fuzzy numbers and
Russell’s Method
Experimental Study on Two-Phase Flow in Horizontal Rectangular Minichannel wi...IJERA Editor
This document summarizes an experimental study on two-phase air-water flow in a horizontal rectangular minichannel with a Y-junction. The study investigated flow patterns, bubble velocity, bubble length, void fraction, and pressure profiles upstream and downstream of the junction. Two flow patterns (slug flow and annular flow) were observed. Pressure loss coefficients were proposed for the pressure drop at the junction. Results were compared to existing correlations from literature to analyze frictional pressure drops, void fractions, and other two-phase flow parameters.
Some Remarks on Prime Submodules in Weak Co-Multiplication ModulesIJERA Editor
Throughout this paper, the entire ring will be treated as commutative ring with non-zero identity and all the
modules will be treated as unitary modules. In this paper we shall discuss some remarks on prime submodules in
weak co-multiplication modules.
Study of Surface Roughness Characteristics of Drilled Hole in Glass Fiber Rei...IJERA Editor
Now-a-days glass fiber-reinforced plastics (GFRP) are always applicable in variety of engineering applications.
It is used in aerospace, automotive and aircraft industries due to their well known properties. Milling of GFRP
composite materials is very difficult due to its heterogeneity and the number of troubles like as surface
delamination during machining affects uniqueness of the material and the machining parameters. Present paper
focuses the experimental details to find out delamination factor on GFRP composite laminates by using
Taguchi‟s DOE L9 orthogonal array. The main objective of the present work is to optimize the process
parameters in the drilling of GFRP composite using Taguchi DOE and to find the significance of each process
parameter using ANOVA. As far as the effect of input factors are considered, the factors drilled material and
spindle speed both have nearly predominant influence on the delamination factor of drilled holes on GFRP
composite by using CNC milling process.
Cryptographic Technique Used Lower and Upper Triangular Decomposition MethodIJERA Editor
In this paper, the main cryptographic technique we will use affine cipher used for encryption and also
decryption by using one of the linear algebra technique lower and upper triangular technique
Effect of Rotation on a Layer of Micro-Polar Ferromagnetic Dusty Fluid Heated...IJERA Editor
This paper deals with the theoretical investigation of effect of rotation on micro-polar ferromagnetic dusty fluid
layer heated from below in a porous medium. Linear stability analysis and normal mode analysis methods are
used to find an exact solution for a flat micro-polar ferromagnetic fluid layer contained between two free
boundaries . In case of stationary convection, the effect of various parameters like medium permeability
parameter, non-buoyancy magnetization parameter, micro-polar coupling parameter, spin-diffusion parameter,
micro-polar heat conduction parameter, dust particles parameter and rotation parameter has been analyzed and
results are depicted graphically. In the absence of dust particles, rotation, micro-viscous effect and micro-inertia,
the sufficient condition is obtained for non-oscillatory modes
A Fast Floating Point Double Precision Implementation on FpgaIJERA Editor
In the modern day digital systems, floating point units are an important component in many signal and image
processing applications. Many approaches of the floating point units have been proposed and compared with
their counterparts in recent years. IEEE 754 floating point standard allows two types of precision units for
floating point operations, single and double. In the proposed architecture double precision floating point unit is
used and basic arithmetic operations are performed. A parallel architecture is proposed along with the high
speed adder, which is shared among other operations and can perform operations independently as a separate
unit. To improve the area efficiency of the unit, carry select adder is designed with the novel resource sharing
technique which allows performing the operations with the minimum usage of the resources while computing
the carry and sum for „0‟ and „1‟. The design is implemented using the Xilinx Spartan 6 FPGA and the results
show the 23% improvement in the speed of the designed circuit
Physico-Chemical Evaluation of Wastewater from Abattoir, Brewery, Soap and Oi...IJERA Editor
The discharge of industrial wastewater in the city of Moundou deteriorates the quality of surface and
underground water and soils. In this study the physicochemical quality of industrial effluents was investigated in
different seasons (summer, winter and rainy). Three sampling sites were used (Central Abattoir discharge,
Cotontchad (soap and oil factory) discharge, and Brewery discharge), for sampling from July 2013 to December
2014. The following physico-chemical parameters were determined: pH, Temperature, EC, dissolved oxygen,
COD, BOD5, NO3,PO4,SO4. Also, the heavy metals: Cu, Cd, Mn, Ni, Pb, As, Zn, Cr, Fe, Al, was analyzed on
spectrophotometers and results were compared with World Health Organization (WHO) permissible limits.
This study revealed that most parameters were much higher than the permissible limit for wastewater
discharges:some parameters were to higher: pH (12,6), Temperature (37,8 °C), C.E (4270 μS/cm), organic
matters: COD (1200 mg/l), SO4 (1280 mg/l), PO4(4460 mg/l), NO3 (63,6 mg/l), (Fe (63,34 mg/l), Zn (13,27
mg/l), Pb (4,0 mg/l), Cu (25,34 mg/l), Cd (31,78 mg/l), Cr (5,9 mg/l), Ni (39,5 mg/l. The study concludes that
discharge of effluents by the companies; factory and materials from other anthropogenic sources severely
pollute the Logone River with heavy metals and other pollutants. We recommended that each industry recycle
its wastewater and put in place specific treatment plants, because pollutants to eliminate vary depending on the
industry.
Ergonomic Evaluation of the Angle of Abduction in Laptops EnvironmentIJERA Editor
Laptops in 21st century are an integral part of every professional in vivid fields. Off late there has been
emergence of several ergonomic injuries such as repetitive strain injuries (RSIs) due to extensive usage of
laptops, which can be closely linked with applied force and postures. This study investigated the effect of
various angles of keyboard on the applied force and motor action plus response time while performing five
distinct tasks. On the basis of literature two different laptops were selected for performing different tasks. For
each case the three levels of platform angle were considered as 0°, 5°, and 10°. Male subjects were selected to
perform five distinct tasks for each platform angle for both laptops. The force applied (in milli-volts) and the
motor action plus response time (milli-seconds) were recorded using an oscilloscope. The data collected were
analyzed through ANOVA using MINITAB software. The abduction angle with the least mean response time
and applied force were considered as the best from ergonomics viewpoint. The ANOVA results showed that the
angle of abduction for both laptops (small and large) do have significant effect on applied force but not on motor
action plus response time. The analysis of results indicate that 10° angle of abduction in case of small laptops
should be applied to minimize musculoskeletal disorder and repetitive strain injuries.
Research relevance: This work suggests that those responsible for the function and operation of laptops would
have to redesign the system to reduce injuries, as far as musculoskeletal disorder, repetitive strain injuries and
other related problems are concerned. The present work can be quite useful for the system designers of
tomorrow.
A Fuzzy Inventory Model with Perishable and Aging ItemsIJERA Editor
A parametric multi-period inventory model for perishable items considered in this paper. Each item in the stock perishes in a given period of time with some uncertainty. A model derived for recursive unnormalized conditional distributions of {} given the information accumulated about the inventory level- surviving items processes.
With the concept of 3G & 4G services OCDMA is one of the important technologies, that provide a very high speed communication. In this technology multiple users can communicate simultaneously to transfer different kind of data. OCDMA enables the best use of available bandwidth and the spectrum to represent a cost efficient network. But in a network there is always the requirement to increase the security and the efficiency or the throughput of a multiuser communication in the OCDMA network. The proposed work is about to increase the efficiency in a Noisy channel. Here the work will be performed on impulse noised network. We are here proposing the orthogonal approach along with OCDMA to improve the throughput. We are trying to show the results in terms of noise ratio and the derived throughput. The proposed work is about to reduce this packet loss and to increase the throughput in the noisy network. To overcome this drawback and to increase the throughput we are using the concept of OFDM along with CDMA. This concept is represented as the Orthogonal CDMA.
IOSR Journal of Electronics and Communication Engineering(IOSR-JECE) is an open access international journal that provides rapid publication (within a month) of articles in all areas of electronics and communication engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in electronics and communication engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
The document is the International Journal of Electronics and Communication Engineering & Technology (IJECET) from January 2014. It discusses a hybrid optimization method for multi-user detection in SDMA-OFDM systems that combines genetic algorithms and particle swarm optimization. This approach aims to overcome limitations of existing detection methods. The hybrid method is shown to provide better performance than minimum mean square error and maximum likelihood detection, especially when the number of users is high relative to base station antennas. The document provides details on the proposed hybrid method and compares its performance to other approaches through simulation.
Optimal Channel and Relay Assignment in Ofdmbased Multi-Relay Multi-Pair Two-...ijcnes
Efficient utilization of radio resources in wireless networks is crucial and has been investigated extensively. This letter considers a wireless relay network where multiple user pairs conduct bidirectional communications via multiple relays based on orthogonal frequency-division multiplexing (OFDM) transmission. The joint optimization of channel and relay assignment, including subcarrier pairing, subcarrier allocation as well as relay selection, for total throughput maximization is formulated as a combinatorial optimization problem. Using a graph theoretical approach, we solve the problem optimally in polynomial time by transforming it into a maximum weighted bipartite matching (MWBM) problem. Simulation studies are carried out to evaluate the network total throughput versus transmit power per node and the number of relay nodes
This document summarizes a research paper that analyzes the performance of various digital filters in an OCDMA (Optical Code Division Multiple Access) multi-user environment using 3D codes. The document describes a simulation of a 24-user OCDMA system using different parameters like BER (Bit Error Rate), Q-factor, and eye patterns with filters including Raised Cosine, Gaussian, Fabry Perot, Trapezoidal, and Lorentzian. The analysis found that the system using a Fabry Perot filter had the minimum distortion while maintaining a low BER of 6.81×e-20 for correctly decoded signals.
Multicarrier modulation can be implemented by using Orthogonal Frequency Division Multiplexing (OFDM) to achieve utmost bandwidth exploitation and soaring alleviation attributes profile besides multipath fading. To support delay sensitive and band bandwidth demanding multimedia applications and internet services, MIMO in addition with other techniques can be used to achieve high capacity and reliability. To obtain high spatial rate by transmitting data on several antennas by using MIMO with OFDM results in reducing error recovery features and the equalization complexities arise by sending data on varying frequency levels. Three parameters frequency OFDM, Spatial (MIMO) and time (STC) can be used to achieve diversity in MIMO-OFDM. This technique is dynamic and well-known for services of wireless broadband access. MIMO if used with OFDM is highly beneficial for each scheme and provides high throughput. There are several space time block codes to exploit MIMO OFDM; one of the techniques is called Alamouti Codes. The paper investigates adaptive Alamouti Codes and their application in IEEE 802.11n.
This document discusses an OFDM-based wireless LAN transmitter architecture. It begins with an abstract that describes OFDM signals used in 802.11 wireless LAN systems and the need for high data rate wireless communication. It then provides background on OFDM and orthogonal frequency division multiplexing. The document describes the proposed OFDM-based wireless LAN architecture, which includes modules for time and frequency recovery, channel estimation, and channel coding to protect data from noise and interference during transmission.
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Abstract: Code Division Multiple Access (CDMA) is a spread spectrum technique that uses neither frequency channels nor time slots. With CDMA, the narrow band message (typically digitized voice data) is multiplied by a large bandwidth signal that is a pseudo random noise code (PN code). All users in a CDMA system use the same frequency band and transmit simultaneously. The transmitted signal is recovered by correlating the received signal with the PN code used by the transmitter. The DS - CDMA is expected to be the major medium access technology in the future mobile systems owing to its potential capacity enhancement and the robustness against noise. The CDMA is uniquely featured by its spectrum-spreading randomization process employing a pseudo-noise (PN) sequence, thus is often called the spread spectrum multiple access (SSMA). As different CDMA users take different PN sequences, each CDMA receiver can discriminate and detect its own signal, by regarding the signals transmitted by other users as noise- like interferences. In this project direct sequence principle based CDMA transmitter and receiver is implemented in VHDL for FPGA. Modelsim 6.2(MXE) tool will be used for functional and logic verification at each block. The Xilinx synthesis technology (XST) of Xilinx ISE 9.2i tool will be used for synthesis of transmitter and receiver on FPGA Spartan 3E. Keywords: CDMA, DSSS, BPSK, GOLD code.
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This document analyzes the performance of a four user optical code division multiple access (OCDMA) communication system under the effect of jitter. Simulations were conducted using Rsoft Optsim to evaluate the bit error rate (BER) and Q-factor of the system with jitter varying from 0 to 3 picoseconds. The results show that as jitter increases, BER increases and Q-factor decreases for different fiber lengths of 10km, 30km, 50km and 70km. Specifically, BER varies from 2.11E-02 to 1.71E-02 as jitter increases for a 10km fiber length. For a 30km length, BER increases from 2.11E-02 to 1.71
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.
Analysis of Simulation Parameters of Pulse Shaping FIR Filter for WCDMAijsrd.com
The application of signal processing techniques to wireless communications is an emerging area that has recently achieved dramatic improvement in results and holds the potential for even greater results in the future as an increasing number of researchers from the signal process and communications areas participate in this expanding field. From an industrial viewpoint also, the advanced signal processing technology cannot only dramatically increase the wireless system capacity but can also improve the communication quality including the reduction of all types of interference. The present paper deals with simulation model of square root raised cosine pulse shaping filter for WCDMA with different parameters of the filter at 5Mhz.The present paper deals with study of Simulation Parameters (Number of Bits, Number of Errors) of Pulse Shaping FIR Filter at different value of group delay(2,4,6,8) to the calculate BER for WCDMA.
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Performance Analysis of Multi-QoS Model of OCDMA System by Adopting OPPM Signalling and Switching
1. Rajesh Mishra et al. Int. Journal of Engineering Research and Application www.ijera.com
ISSN : 2248-9622, Vol. 6, Issue 6, ( Part -3) June 2016, pp.37-42
www.ijera.com 37|P a g e
Performance Analysis of Multi-QoS Model of OCDMA System by
Adopting OPPM Signalling and Switching
Rajesh Mishra1
, N.K.Shukla2
C.K.Dwivedi3
Department Of Electronics & Communication University Of Allahabad, India
E mail: rajeshmishra26@yahoo.co.in
ABSTRACT
In this paper, optical CDMA which combines the large bandwidth of the fibre medium with the flexibility of the
CDMA technique to achieve high speed connectivity has been used. For achieving this purpose, OPPM
signalling and switching techniques have been employed. This helps in the achievement of high tolerance to
Multiple Access Interference, further resulting in improvement of both the Bit Error Rate and optical channel
capacity without the need to decrease the light pulse width. An OPPM scheme to support multimedia services
with different transmission rates and Quality of Service requirements is proposed. Packet Switching technique
has been employed to help in the transfer of data in the form of packets from the source to the destination via a
specified route. The results are calculated by using PPM signalling and switching technology.But switching
technology has been found to be far better than the OOK-OCDMA if the average power has been considered as
the restraining factor.
Keywords: CDMA, OCDMA, BER,PPM,OOK, PER,MAI, QoS, Switching.
I.Introduction
Code division multiple access (CDMA)[1]
is a
channel access method used by various radio
communication technologies.
CDMA [4]
is an example of multiple access where
several transmitters can send information
simultaneously over a single communication
channel. This allows several users to share a band
of frequencies (see bandwidth). To permit this
without undue interference between the users,
CDMA employs spread-spectrum
technology and a special coding scheme (where
each transmitter is assigned a code). CDMA is used
as the access method in many mobile phone
standards such as CDMA One, CDMA2000 (the
3G evolution of CDMA One), and WCDMA (the
3G standard used by GSM carriers), which are
often referred to as simply CDMA.
Each user in a CDMA system uses a different
codetomodulate their signal. Choosing the codes
used to modulate the signal is very important in the
performance of CDMA systems. The best
performance will occur when there is good
separation between the signal of a desired user and
the signals of other users. The separation of the
signals is made by correlating the received signal
with the locally generated code of the desired user.
If the signal matches the desired user's code then
the correlation function will be high and the system
can extract that signal. If the desired user's code has
nothing in common with the signal the correlation
should be as close to zero as possible (thus
eliminating the signal), this is referred to as cross-
correlation. If the code is correlated with the signal
at any time offset other than zero, the correlation
should be as close to zero as possible. This is
referred to as auto-correlation and is used to reject
multi-path interference.
An analogy to the problem of multiple
access is a room (channel) in which people wish to
talk to each other simultaneously. To avoid
confusion, people could take turns speaking (time
division), speak at different pitches (frequency
division), or speak in different languages (code
division). CDMA is analogous to the last example
where people speaking the same language can
understand each other, but other languages are
perceived as noise and rejected. Similarly, in radio
CDMA, each group of users is given a shared code.
Many codes occupy the same channel, but
onlyusers associated with a particular code can
communicate.
RESEARCH ARTICLE OPEN ACCESS
2. Rajesh Mishra et al. Int. Journal of Engineering Research and Application www.ijera.com
ISSN : 2248-9622, Vol. 6, Issue 6, ( Part -3) June 2016, pp.37-42
www.ijera.com 38|P a g e
II. Optical Code-Division Multiple-Access
In general, CDMA belongs to two basic categories:
Synchronous (Orthogonal codes) and
Asynchronous (Pseudorandom codes).
An optical code-division multiple-access
(OCDMA) [2]
system employing overlapping pulse-
position modulation (OPPM) is proposed to support
multimedia services with different bit-rate and
quality-of-service (QoS) requirements in OCDMA
networks. Both wrapped OPPM (WOPPM) and
unwrapped OPPM (UOPPM) are considered. The
proposed system achieves multi-rate and multi-QoS
transmission by using multi-length variable-weight
optical orthogonal codes (MLVW-OOCs) as
signature sequences and using different values of
OPPM modulation parameters. Furthermore,
numerical analysis is performed for two different
receiver structures, namely, correlation receivers
with and without hard-limiters. In our analysis, the
multiple-accessinterference(MAI) is considered as
the main performance limiting factor. In addition,
the performance of the proposed system is
evaluated and compared to that of traditional OOK-
OCDMA system. Our results reveal that under both
pulse width and throughput constraints, the
performances of the proposed WOPPMand
UOPPM-OCDMA [5]
systems are significantly
superior to that of OOK-OCDMA system.
In an O-CDMA[3]
system, each bit is divided up
into n time periods, called chips. By sending a short
optical pulse during some chip intervals, but not
others, an optical signature sequence, or code word,
can be created. Each user on the O-CDMA system
has a unique signature sequence. The encoder of
each transmitter represents each 1 bit by sending
the signature sequencehowever; a binary 0 bit is not
encoded and is represented using an all-zero
sequence. Since each bit is represented by a pattern
of lit and unlit chips, the bandwidth of the data
stream is increased. O-CDMA is therefore a
spread-spectrum technology.
Optical code-division multiple access (OCDMA)
provides another dimension for multiple access
other than time- and optical frequency domains.
Unfortunately, it has long remained outside the
main stream of optical communications R&D since
its proposal in the mid-1970s followed by
experimental demonstrations in the 1980s. This is
mainly due to immaturity of optical devices, which
are proprietary to OCDMA, such as optical
encoder/decoder and optical threshold device. The
crosstalk between the different users sharing the
common channel, known as the multiple access
interference (MAI), and the signal-interference beat
noise is the main source of bit errors. The reduction
of the MAI and the beat noise are big challenges to
make OCDMA a practical option for FTTH
systems. Demonstrations of OCDMA system test
hasalso been conducted [6]
. Being encouraged by
the progresses, OCDMA now deserves revisiting as
a multiple-access technique forFTTH system[7].
In
this paper; we will first highlight the OCDMA
systems.
Optical Code Division Multiple Access
III. Interference
A phenomenon ofinterference[8]
occurs due to the
overlapping of spectra from different users at
network. Dramatic growth rates in capacity
demands in wireless and other broadband systems
have resulted in a rise in the use of communication
networks in which multiple users share common
communication resources. A significant
consequence of this trend is the increasing presence
of multiple-access interference (MAI), which arises
in communication systems employing non-
orthogonal multiplexing i.e. in multiple-access
systems. This issue arises naturally, for example, in
code division multiple-access (CDMA)
communication systems using non-orthogonal
spreading codes. It also arises in orthogonally
multiplexed wireless channels, such as time-
division multiple-access (TDMA) and orthogonal
frequency division multiple-access (OFDMA)
channels, due to effects such as multipath or non-
ideal frequency channelization, and in wire line
channels such as those arising in digital subscriber
line (DSL) systems or power line communications
(PLCs) in which crosstalk and other types of
interference are major impairments. MAI also
arises in optical Wave-Division Multiplexing
(WDM) systems due to mode interactions caused
by nonlinearities.
3. Rajesh Mishra et al. Int. Journal of Engineering Research and Application www.ijera.com
ISSN : 2248-9622, Vol. 6, Issue 6, ( Part -3) June 2016, pp.37-42
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Multiple Access Interference
(Decoded Signal, MAI Noise Rejection)
In digital transmission, the number of bit
errors is the number of received bits of a data
stream over a communication channel that has been
altered due to noise, interference, distortion or bit
synchronization errors.
The Bit Error Rate (BER)
[6]
is the number
of bit errors per unit time. The Bit Error
Ratio
[7]
(also BER) is the number of bit errors
divided by the total number of transferred bits
during a studied time interval. BER is a unit less
performance measure, often expressed as a
percentage.
The bit error probability[7]
(Pe)is the
expectation value of the bit error ratio. The bit error
ratio can be considered as an approximate estimate
of the bit error probability. This estimate is
accurate for a long time interval and a high number
of bit errors.
The packet error ratio(PER) [7]
is the
number of incorrectly received data packets divided
by the total number of received packets. A packet is
declared incorrect if at least one bit is erroneous.
The expectation value of the PER is denoted
packet error probabilityPp, which for a data
packet length of N bits can be expressed as:
Assume that the bit errorsare independent
from each other. For small bit error probabilities,
this is approximately,
In communication system,the receiver BER is
affected by the transmission channel noise,
interference, distortion, bit synchronization
problems, attenuation, wireless multipath fading,
etc. The BER may be improved by choosing a
strong signal strength (unless this causes cross-talk
and more bit errors), by choosing a slow and robust
modulation scheme or line coding scheme, and by
applying channel coding schemes such as
redundant forward error correction codes.
The transmission BER is the number of
detected bits that are incorrect before error
correction, divided by the total number of
transferred bits (including redundant error codes).
The information BER, approximately equal to the
decoding error probability, is the number of
decoded bits that remain incorrect after the error
correction, divided by the total number of decoded
bits (the useful information). Normally the
transmission BER is larger than the information
BER. The information BER is affected by the
strength of the forward error correction code.
BIT ERROR RATE IN BPSK, QPSK, DIFFERENTIA
ENCODED BPSK
4. Rajesh Mishra et al. Int. Journal of Engineering Research and Application www.ijera.com
ISSN : 2248-9622, Vol. 6, Issue 6, ( Part -3) June 2016, pp.37-42
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IV. Optical CDMA for Access Networks
In an O-CDMA system, each bit is divided up into
n time periods, called chips. By sending a short
optical pulse during some chip intervals, but not
others, an optical signature sequence, or code word,
can be created. Each user on the O-CDMA system
has a unique signature sequence. The encoder of
each transmitter represents each 1 bit by sending
the signature sequence; however, a binary 0 bit is
not encoded and is represented using an all-zero
sequence. Since each bit is represented by a pattern
of lit and unlit chips, the bandwidth of the data
stream is increased. O-CDMA is therefore a
spread-spectrum technology.
V On-Off Keying
On-off keying (OOK)[2]
denotes the simplest form
of Amplitude-Shift Keying (ASK) modulation that
represents digital data as the presence or absence of
a carrier wave[1]
in its simplest form, the presence of
a carrier for a specific duration represents a binary
one, while its absence for the same duration
represents a binary zero. Some more sophisticated
schemes vary these durations to convey additional
information. It is analogous to unipolar encoding
line code.
On-off keying [5]
is most commonly used to transmit
Morse code over radio frequencies referred to as
CW (continuous wave) operation, although in
principle any digital encoding scheme may be used.
OOK has been used in the ISM bands to transfer
data between computers.
For example OOK is more spectrally efficient than
frequency-shift keying, but more sensitive to noise
when using a regenerative receiver or a poorly
implemented super heterodyne receiver. For a
given data rate, the bandwidth of a BPSK (Binary
Phase Shift keying) signal and the bandwidth of
OOK signal are equal.
In addition to RF carrier waves, OOK is also used
in optical communication systems (e.g. IrDA). In
aviation, some possibly unmanned airports have
equipment that let pilots key their VHF radio a
number of times in order to request an Automatic
Terminal Information Service broadcast, or turn on
runway lights.
VI Qualityof Service
Quality of service (QoS)[8]
is the overall
performance of a telephony or computer network,
particularly the performance seen by the users of
the network.
To quantitatively measure quality of service,
several related aspects of the network service are
often considered, such as error rates, bit rate,
throughput, transmission delay, availability, jitter,
etc.
Qualityof service (QoS)[10]
is particularly important
for the transport of traffic with special
requirements. In particular, much technology has
been developed to allow computer networks to
become as useful as telephone networks for audio
conversations, as well as supporting new
applications with even stricter service demands.
In the field of telephony, quality of service[12]
was
defined by the ITU in 1994. Quality of service
comprises requirements on all the aspects of a
connection, such as service response time, loss,
signal-to-noise ratio, crosstalk, echo, interrupts,
frequency response, loudness levels, and so on. A
subset of telephony QoS is grade of service (GoS)
requirements, which comprises aspects of a
connection relating to capacity and coverage of a
network, for example guaranteed maximum
blocking probability and outage probability. In the
field of computer networking and other packet
switching telecommunication networks, the traffic
engineering term refers to resource reservation
control mechanisms rather than the achieved
service quality. Quality of service is the ability to
provide different priority to different applications,
users, or data flows, or to guarantee a certain level
of performance to a data flow. For example, a
required bit rate, delay, jitter, packet dropping
probability and/or bit error rate may be guaranteed.
Quality of service guarantees are important if the
network capacity is insufficient, especially for real-
time streaming multimedia applications such as
voice over IP, online games and IP-TV, since these
often require fixed bit rate and are delay sensitive,
and in networks where the capacity is a limited
resource, for example in cellular data
communication.
The performance of encoded overlapping pulse
position modulation (OPPM)[1]
with at most two
pulse positions per pulse width is investigated for
an optical direct-detectionchannel under
communication constraints. It is shown that under
bandwidth and throughput constraints OPPM, with
two pulse positions per pulse width, outperforms
PPM when the overlap is chosen properly and the
throughput is greater than 0.2 nats/slot. This makes
it possible to increase the throughput and/or
decrease the energy of the OPPM system,while
maintaining the same performance as PPM. The
energy saving when using OPPM[12]
instead of
PPM to transmit reliably a given amount of
information is determined for different values of
overlapping indices. The maximum throughput that
can be achieved under average power and
bandwidth constraints (with error probability not
exceeding 10-5
) is also determined.
5. Rajesh Mishra et al. Int. Journal of Engineering Research and Application www.ijera.com
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VII. Switching System Fundamentals
Telecommunications switching systems generally
perform three basic functions: they transmitsignals
over the connection or over separate channels to
convey the identity of the called (and sometimes
the calling) address (for example, the telephone
number), and alert (ring) the called station; they
establish connections through a switching network
for conversational use during the entire call; and
they process the signal information to control and
supervise the establishment and disconnection of
the switching network connection.
In some data or message switching when real-time
communication is not needed, the switching
network is replaced by a temporary memory for the
storage of messages. This type of switching is
known as store-and-forward switching.
Signalling and control: The control of circuit
switching systems is accomplished remotely by a
specific form of data communication known as
signalling. Switching systems are connected with
one another by telecommunication channels known
as trunks. They are connected with the served
stations or terminals by lines.
In some switching systems the signals for a call
directly control the switching devices over the
same path for which transmission is established.
For most modern switching systems the signals for
identifying or addressing the called station are
received by a central control thatprocesses calls on
a time-shared basis. Central controls receive and
interpret signals, select and establish
communication paths, and prepare signals for
transmission. These signals include addresses for
use at succeeding nodes or for alerting (ringing) the
called station.
Most electronic controls are designed to process
calls not only by complex logic but also by logic
tables or a program of instructions stored in bulk
electronic memory. The tabular technique is known
as translator. The electronic memory is now the
most accepted technique and is known as stored
program control (SPC). Either type of control may
be distributed among the switching devices rather
than residing centrally.
VIII. Simulation and Description
In this circuit, optical CDMA which combines the
large bandwidth of the fibre medium with the
flexibility of the CDMA technique to achieve high
speed connectivity has been used. For achieving
this purpose, OPPM signalling and SWITCHING
techniques have been employed. This helps in the
achievement of high tolerance to Multiple Access
Interference, further resulting in improvement of
both the Bit Error Rate and Optical channel
capacitywithout the need to decrease the light pulse
width, by using BER Analyser and optical
spectrum Analyser for various signal bandwidths.
Circuit and Waveform Analysis inOptisystem13.0
Components used: Uniform Fibre Bragg Grating,
Photo detector PIN, Electrical Subs tractor, Low
Pass Filter, Optical Spectrum Analyser, BER
Analyser.
Simulation parameters
Uniform Fibre Bragg Grating_7, Uniform Fibre
Bragg Grating_9
Frequency= 1552.5nm, Frequency =1550 nm
Bandwidth= 0.3nm,Bandwidth=0.3nm
Low pass Bessel Filter: Cut off Frequency= 0.65
*Signal Bitrate MHz’s
IX. Result and Output Wave form
Output Waveform – Optical Spectrum Analyzer
Output Waveform – Optical Spectrum Analyzer_1
6. Rajesh Mishra et al. Int. Journal of Engineering Research and Application www.ijera.com
ISSN : 2248-9622, Vol. 6, Issue 6, ( Part -3) June 2016, pp.37-42
www.ijera.com 42|P a g e
Bit Error Rate Analyzer
X. Conclusion
In this paper, a multi rate and multi
Quality of Service transmission system has been
proposed using OPPM techniques and
SWITCHING techniques. When the OCDMA
system is being modulated using OPPM then it is
found to be than OOK. The switching technique
used is PACKET switching in which the data is
being sent in packets from the source to the
destination via a specified route (VIRTUAL
PACKET SWITCHING). In this technique a large
amount of data can be easily transmitted. The
results have been validated using the Optisystem
13.0 simulator.
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