call for papers, research paper publishing, where to publish research paper, journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJEI, call for papers 2012,journal of science and technolog
The document analyzes the bit error rate (BER) performance of the mobile WiMAX physical layer under different communication channels and modulation techniques. It simulates BER and signal-to-noise ratio (SNR) using the Stanford University Interim (SUI) channel models, which model six different channel conditions for varying terrain types. The performance is evaluated for different data rates and modulation schemes like BPSK and OFDMA under the SUI channel models.
This document discusses the principles of OFDMA modulation used in LTE networks. It explains that OFDMA divides the available bandwidth into multiple orthogonal subcarriers. Each subcarrier can be modulated with different modulation schemes like QPSK, 16-QAM, or 64-QAM to transmit multiple bits per symbol. This improves spectral efficiency over traditional FDMA. The document also covers other LTE concepts like channel coding rates, link adaptation using CQI, and use of both FDD and TDD duplexing modes.
This document discusses Orthogonal Frequency Division Multiple Access (OFDMA) and related topics. It provides information on:
- The structure and principles of OFDM symbols, including how they are constructed from orthogonal subcarriers modulated by parallel data streams.
- Challenges caused by carrier frequency offsets and sampling time offsets at the receiver, and how symbol synchronization is needed.
- Channel estimation techniques in OFDMA systems, including least squares estimation, block-type and comb-type pilot structures, and linear/second-order interpolation methods.
- How OFDMA exploits multiuser diversity by adaptively allocating subcarriers to users experiencing favorable channel conditions.
The document discusses various medium access control (MAC) protocols for wireless networks. It describes challenges with applying carrier sense multiple access with collision detection (CSMA/CD) to wireless networks due to problems like hidden and exposed terminals. It then covers different MAC schemes like space division multiple access (SDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), and code division multiple access (CDMA) that aim to address these challenges. Specific protocols discussed in more detail include Aloha, slotted Aloha, and how TDMA can be used for fixed or dynamic channel allocation.
Orthogonal Frequency Division Multiplexing, OFDM uses a large number of narrow sub-carriers for multi-carrier transmission to overcome the effect of multi path fading problem. LTE uses OFDM for the downlink, from base station to terminal to transmit the data over many narrow band careers of 180 KHz each instead of spreading one signal over the complete 5MHz career bandwidth. OFDM meets the LTE requirement for spectrum flexibility and enables cost-efficient solutions for very wide carriers with high peak rates.
The primary advantage of OFDM over single-carrier schemes is its ability to cope with severe channel conditions. Channel equalization is simplified. The low symbol rate makes the use of a guard interval between symbols affordable, making it possible to eliminate inter symbol interference (ISI).
This document discusses key concepts of OFDMA and WiMAX including:
1. OFDMA divides subcarriers into groups called sub-channels that can be allocated to different receivers or transmitters.
2. Sub-channelization allows a WiMAX base station to allocate more transmit power to users with lower signal strength and less power to those with higher signal strength.
3. A cyclic prefix is used to avoid intersymbol interference and intercarrier interference.
This document describes a simulator designed to analyze bit error rates using orthogonal frequency division multiplexing (OFDM) under different modulation schemes and channel conditions. The simulator was implemented in MATLAB and allows users to choose modulation types, channel types (AWGN, Rayleigh, Rician), and other parameters. It then generates plots of bit error rate versus signal-to-noise ratio for performance analysis. Screenshots of the user interface are provided along with sample output plots and discussion of the simulator design and capabilities.
This document discusses the principles of OFDMA modulation used in LTE networks. It explains that OFDMA divides the available bandwidth into multiple orthogonal subcarriers. Each subcarrier can be modulated with different modulation schemes like QPSK, 16-QAM, or 64-QAM to transmit multiple bits per symbol. This improves spectral efficiency over traditional FDMA. The document also covers other LTE concepts like channel coding rates, link adaptation using CQI, and use of both FDD and TDD duplexing modes.
This document discusses Orthogonal Frequency Division Multiple Access (OFDMA) and related topics. It provides information on:
- The structure and principles of OFDM symbols, including how they are constructed from orthogonal subcarriers modulated by parallel data streams.
- Challenges caused by carrier frequency offsets and sampling time offsets at the receiver, and how symbol synchronization is needed.
- Channel estimation techniques in OFDMA systems, including least squares estimation, block-type and comb-type pilot structures, and linear/second-order interpolation methods.
- How OFDMA exploits multiuser diversity by adaptively allocating subcarriers to users experiencing favorable channel conditions.
The document discusses various medium access control (MAC) protocols for wireless networks. It describes challenges with applying carrier sense multiple access with collision detection (CSMA/CD) to wireless networks due to problems like hidden and exposed terminals. It then covers different MAC schemes like space division multiple access (SDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), and code division multiple access (CDMA) that aim to address these challenges. Specific protocols discussed in more detail include Aloha, slotted Aloha, and how TDMA can be used for fixed or dynamic channel allocation.
This document provides a tutorial on multi-access orthogonal frequency-division multiplexing (OFDMA) technology. It describes the OFDMA system architecture, including duplexing techniques, multiple access methods, and diversity methods. It also provides an example OFDMA downlink specification and uplink specification, and describes carrier allocation techniques using special permutations. The tutorial aims to provide insight into OFDMA technology for potential use in wireless regional area network systems.
Digital Communication 80 Marks Sample Test Paperprathik
This document is a sample question paper for the subject Digital Communication. It contains 6 questions with a total of 80 marks. Question 1 has 16 marks and asks students to attempt 4 out of 6 parts related to concepts like channel capacity, pulse modulation, bandwidth, baud rate, and WDM. Question 2 has 12 marks and asks students to attempt 3 out of 4 parts related to PWM, PPM, data formats, and TDMA. Question 3 has 12 marks and asks students to attempt 3 out of 4 parts distinguishing baseband and passband transmission, describing QAM, defining ASK and FSK.
Multiplexing generally refers to independent signals, those produced by different sources. SO it is a question of how to share the spectrum with these users. In OFDM the question of multiplexing is applied to independent signals but these independent signals are a sub-set of the one main signal.
In OFDM the signal itself is first split into independent channels, modulated by data and then re-multiplexed to create the OFDM carrier.
OFDM is a combination of modulation and multiplexing.
This document summarizes a research paper that analyzes the performance of different pilot-based channel estimation schemes for OFDM systems using QPSK and 16-QAM modulation over Rayleigh fading channels with Doppler frequency shifts. It compares block-type pilot arrangement, which inserts pilots into all subcarriers periodically, to comb-type arrangement, which inserts pilots into each symbol and requires interpolation. It evaluates channel estimation algorithms like LS, LMMSE, SVD for block pilots and linear, quadratic, and cubic spline interpolation for comb pilots. The goal is to analyze how bit error rate is affected by Doppler shifts. Simulations are conducted in MATLAB to compare the schemes.
This document summarizes a student project on OFDM transmitters and receivers. It includes an introduction to OFDM that describes its use of orthogonal subcarriers. It also compares single carrier modulation to multi-carrier modulation using OFDM. The document outlines the basic OFDM transmitter and receiver block diagrams. It discusses the constellation mapper, IFFT block, cyclic prefix, and design approaches for these blocks. Simulation results are presented comparing transmitted and received signals. BER performance is evaluated for different modulation schemes like QPSK and QAM. The document concludes that OFDM provides high bandwidth efficiency and overcomes interference through the IFFT and cyclic prefix.
Cooperative Diversity - An Introduction to Cooperative CommAshish Meshram
The document provides an introduction to cooperative diversity and cooperative communication techniques. It discusses the motivation for cooperative diversity as a way to achieve spatial diversity without multiple antennas at mobile units. The key aspects covered include:
- Cooperative diversity protocols like amplify-and-forward (AF) and decode-and-forward (DF) where the relay assists transmission from the source to the destination.
- The application of cooperative diversity techniques to improve cellular capacity and coverage, wireless local area networks, vehicle-to-vehicle communication, and wireless sensor networks.
- The mathematical modeling of the relay channel and simplified single-relay system models for AF and DF protocols.
- Analysis of outage probability for the AF protocol and
This project deals with investigations on development of OFDM based baseband receiver for wireless application. After carrying out initial studies on OFDM based transmitter and receiver, taking into account industrial requirements, an OFDM based baseband receiver has been configured. The block schematic of such a receiver comprises of RF module, ADC fallowed by Digital Down Converter together with the cyclic prefix remover block, serial to parallel converter, FFT module, parallel to serial converter and pilot extractor, the subsequence output is subjected to channel equalization and symbol demapping resulting in the output data that can be processed appropriately.
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
OFDM is a digital multi-carrier modulation technique that divides the available spectrum into multiple orthogonal subcarriers. It allows high spectral efficiency by spacing the carriers to maintain orthogonality even when their spectra overlap. The document provides an intuitive explanation of OFDM using analogies like a shower head vs faucet and multiple smaller trucks vs one large truck. It explains how OFDM provides resistance to interference by spreading data across orthogonal subcarriers rather than a single carrier. The key concept of orthogonality allows the subcarriers to overlap without interference by ensuring the area under one subcarrier's frequency multiplied by another is always zero.
The document discusses Orthogonal Frequency Division Multiplexing (OFDM) and its applications in various wireless communication standards. It begins with the motivation for moving from single carrier to multi-carrier modulation schemes to support higher data rates. It then provides an overview of Frequency Division Multiplexing (FDM) and OFDM, explaining the basic principles of OFDM including orthogonality, modulation, and an illustrative example. The document discusses the OFDM transceiver and bit error rate performance in AWGN and Rayleigh fading channels. It also covers some applications and standards that use OFDM such as Digital Audio Broadcasting (DAB), Digital Video Broadcasting (DVB-T), and various IEEE 802.11 wireless networking standards.
The document provides an overview of ATSC Mobile TV and how it works. It discusses the challenges of mitigating mobile fading and maintaining backward compatibility with legacy receivers. It introduces the dual stream system used by ATSC Mobile TV to transmit an HDTV/SDTV stream and a separate mobile stream. It describes the cross-layer design of ATSC Mobile TV, which uses new channel coding, training signals, and signaling to address mobile fading while maintaining compatibility. It also outlines the basic blocks of the ATSC Mobile TV transmitter and receiver.
Orthogonal Frequency Division Multiplexing (OFDM)Gagan Randhawa
The document discusses Orthogonal Frequency Division Multiplexing (OFDM), including its principles, advantages, disadvantages and applications. OFDM divides the available spectrum into multiple orthogonal subcarriers, each modulated with a low data rate stream. This makes OFDM robust to multipath fading and intersymbol interference. While OFDM provides high data rates and spectral efficiency, it suffers from issues like high peak-to-average power ratio and sensitivity to frequency errors. OFDM is used in technologies like WiFi, WiMAX and digital audio/video broadcasting.
This document discusses the effects of time offset (TO) and carrier frequency offset (CFO) on orthogonal frequency division multiplexing (OFDM) systems and proposes interference cancellation techniques. It introduces the OFDM system model and how CFO causes loss of orthogonality between subcarriers, resulting in inter-carrier interference (ICI) that degrades performance. The paper proposes an ICI reduction scheme using self-cancellation and evaluates its performance compared to standard OFDM. It also discusses using space-time block coding (STBC) with OFDM to improve performance by reducing bit error rate (BER) under different signal-to-noise ratios. Simulation results show STBC effectively mitigates the effects of inter-
This document summarizes a research paper that proposes a content-based hybrid DWT-DCT watermarking technique for image authentication in color images. The technique embeds statistical features extracted from the host image as the watermark. Four different statistical features are used to generate the watermark - the Frobenius norm, mean, standard deviation, and combined mean and standard deviation of the host image blocks. The watermark is then embedded into the host image by applying both DWT and DCT transforms. During extraction, the same process is applied to extract the watermark for authentication. Experimental results show the technique is robust against various attacks like compression, noise, and filters.
The document proposes a fast handoff scheme for IEEE 802.11 wireless networks using virtual access points. It aims to reduce handoff latency, which is primarily caused by the probe delay during scanning for new access points. The scheme uses selective scanning to identify neighboring access points with strong signals. It performs pre-registration of the mobile host with neighboring access points to transfer security contexts in advance. A virtual access point handles communication between the mobile host and registered access points to enable fast switching during handoff. Buffering at the virtual access point allows seamless data transfer when the connection changes between access points.
The document discusses tensile properties of long jute fiber reinforced polypropylene composites. It begins with an abstract that states the objective is to test tensile properties of composites made from chemically treated long jute fibers reinforced in polypropylene at different weight ratios. The results showed tensile strength and modulus increased for treated fiber composites compared to plain polypropylene, with up to a 28.4% increase for 15% NaOH treated fibers at 10% weight ratio. The introduction provides background on composites and defines them. It also describes the phases in a composite including polypropylene matrix and jute fiber reinforcement. Experimental details on materials and fiber extraction are then presented.
This document summarizes research into optimizing process parameters for Eli-Twist yarn production. Eli-Twist yarn is produced using Suessen Elite compact spinning technology and has advantages over traditional two-ply yarns. The distance between roving strands and negative pressure applied in the suction zone can substantially impact yarn quality. Ten trials were conducted varying these two parameters. The effects on yarn fineness, strength, elongation, imperfections and hairiness were evaluated. A process capability index (Cpk) was used to assess yarn quality. The goal was to optimize the parameters to improve Eli-Twist yarn quality.
A precise termination condition of the probabilistic packet marking algorithm...Mumbai Academisc
This document summarizes a research project that proposes a precise termination condition for the probabilistic packet marking (PPM) algorithm. The PPM algorithm allows routers to encode path information onto packets during a denial of service (DoS) attack, enabling the victim to reconstruct the attack graph. However, the existing PPM algorithm lacks a well-defined termination condition, and cannot handle multiple attackers. The proposed project aims to define a termination condition to ensure the reconstructed graph accurately represents the actual attack paths. It also extends the algorithm to support tracing packets from multiple attackers.
This document summarizes a research paper that proposes improvements to the probabilistic packet marking (PPM) algorithm for detecting the path of distributed denial-of-service attacks. The PPM algorithm allows routers to mark attack packets with identification information based on a predetermined probability. However, its termination condition is not well-defined, which can result in an incorrectly constructed attack path. The paper proposes a modified PPM algorithm called rectified PPM (RPPM) that defines a precise termination condition to guarantee the constructed attack path is correct with a specified level of confidence. An experimental framework is designed to test the RPPM algorithm under different packet marking probabilities and network structures.
An enhanced ip traceback mechanism for tracking the attack source using packe...IAEME Publication
The document discusses an enhanced IP traceback mechanism (EITM) to more efficiently trace the source of distributed denial of service (DDoS) attacks. EITM aims to reduce the number of packets required for traceback by improving existing linear and remainder packet marking schemes. It analyzes challenges in tracing attackers due to the stateless nature of the internet and proposes that an effective traceback scheme minimizes required packets. The main goal is a mechanism that needs a number of packets almost equal to the number of hops to reconstruct the attack path more efficiently.
Energy Saving DSR and Probabilistic Rebroadcast Mechanism are used to Increas...IJTET Journal
Abstract- MANETs are infrastructure less and can be set up anytime anywhere. Due to high mobility of nodes in mobile ad hoc networks (MANETs), there exist frequent link breakages which lead to frequent path failures and route discoveries. The overhead of a route discovery cannot be neglected. In a route discovery, broadcasting is a fundamental and effective data broadcasting mechanism, where a mobile node blindly rebroadcasts the first received route request packets unless it has a route to the destination, and thus it causes the broadcast storm problem and without consider the nodes energy level of route selection it leads to reduce the network lifetime. In this paper proposed to focus is on a two mechanism ESDSR and Neighbor coverage based Probabilistic rebroadcast to overcome those problems. A Energy Saving Dynamic Source Routing in MANETs (ESDSR) which will efficiently utilize the battery power consideration in the route selection time of mobile nodes in such a way that the network will get more life time and Neighbor coverage based Probabilistic rebroadcast mechanism, which can significantly decrease the number of retransmissions so as to reduce the routing overhead, and can also improve the routing performance. The simulation was carried out using the NS-2 network simulator.
A Neighbor Coverage-Based Probabilistic Rebroadcast for Reducing Routing Ove...
Similar to call for papers, research paper publishing, where to publish research paper, journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJEI, call for papers 2012,journal of science and technolog
Simulation of Wimax 802.16E Physical LayermodelIOSR Journals
This document summarizes a simulation of the physical layer of WiMAX 802.16e. It describes the design of a WiMAX PHY layer transmitter and receiver model using MATLAB. The model uses 16-QAM modulation over OFDM with 256 subcarriers. Performance is analyzed by transmitting data over AWGN and Rayleigh fading channels and measuring bit loss and packet loss versus SNR and signal power. The results show that bit loss decreases with increasing SNR and decreasing signal power. A combination of SNR=13dB and signal power of 0.6W provided zero bit loss.
Orthogonal frequency-division multiplexing (OFDM)
[1] is a method of encoding digital data on multiple carrier
frequencies. OFDM[1] has developed into a popular scheme
for wideband digital communication, whether wireless or
over copper wires, used in applications such as digital television
and audio broadcasting, DSL Internet access, wireless networks,
powerline networks, and 4G mobile communications. In the
Several wireless standards such as IEEE 802.11a[2] and
HiperLAN2[3].The orthogonality of the subcarriers is no longer
maintained which results in ICI (Inter carrier Interference)[4]
.ICI reduction techniques achieve a better SNR and BER in
OFDM at zero phase noise variance . This technique will use a
large number of closely spaced orthogonal subcarriers to avoid
phase noise. It provides high data rates with sufficient robustness
to radio channel damages. A major problem in OFDM is carrier
frequency offset error between the transmitted and received
signals. Due to this the orthogonality of the subcarriers is no
longer maintained which results in ICI (Inter carrier
Interference). In this paper, we used the ICI self-cancellation
technique and reduced the ICI and improved the BER and SNR
we are also calculate the SNR=15db and 20db at different phase
noise variance.
Channel estimation for high data rate communication in mobile wi max systemIAEME Publication
1) The document discusses channel estimation techniques for high data rate communication in mobile WiMAX systems. It evaluates the performance of two interpolation schemes: Least Square Error (LSE) and Minimum Mean Square Error (MMSE).
2) Through simulation, it is shown that MMSE outperforms LSE, providing better bit error rate performance closer to the ideal channel condition. MMSE estimation results in symbols that are less scattered than LSE when plotted, indicating it is more robust against noise.
3) The key advantage of MMSE is that it takes into account additional information like signal to noise ratio and channel statistics, allowing it to provide smoother interpolation compared to the simpler LSE technique.
1) The document describes a study on improving channel capacity for radio propagation in ocean vessels using MIMO-OFDM systems.
2) It proposes using 16-QAM modulation, Alamouti SFBC coding, and a Rayleigh fading channel model to increase channel capacity and signal reliability despite metal reflections.
3) Simulation results show MIMO techniques like spatial multiplexing and Alamouti coding improve channel capacity and lower bit error rates compared to SISO in engine room and coupled compartment environments.
Performance of OFDM System under Different Fading Channels and Channel CodingjournalBEEI
Orthogonal frequency division multiplexing (OFDM) is a type of multicarrier modulation (MCM) technique in which larger bandwidth is divided into parallel narrow bands each of which is modulated by different subcarriers. All the subcarriers are orthogonal to each other and hence it reduces the interference among various subcarriers. OFDM technique is an efficient modulation technique used in certain wired and wireless application.In a wireless communication channel, the transmitted signal can travel from transmitter to receiver over multiple reflective paths. This results to multipath fading which causes fluctuations in amplitude, phase and angle of arrival of the received signal. For example, the signal which is transmitted from BTS (base transceiver station) may suffer multiple reflections from the buildings nearby, before reaching the mobile station. Such multipath fading channels are classified into slow fading/fast fading and frequency-selective/flat fading channels. This paper discusses the performance of OFDM system using various fading channels and channel coding. The parameter which is known as Bit error rate (BER) is calculated under different fading channels (AWGN, Rayleigh and Rician) for different digital modulation (BPSK, QPSK and QAM) and Channel coding (linear/Cyclic coding). Matlab Simulink tool is used to calculate the BER parameter.
This document analyzes the performance of the physical layer of IEEE 802.16e WiMAX over different channel models. It first describes key features of the WiMAX PHY layer and OFDM modulation technique. It then provides details on the Stanford University Interim (SUI) channel models, which model different propagation environments. The paper presents the simulation model used to analyze performance over these channels using metrics like bit error rate and SNR. Simulation results showing BER curves for different modulation schemes over various SUI channels are presented and discussed. The paper concludes that modulation type and coding rate impact performance between channels, with lower modulation and coding providing better performance at lower SNR.
The document analyzes the performance of IEEE 802.16d under the Stanford University Interim (SUI) channel model. It investigates the bit error rate of IEEE 802.16d using different SUI channel models and digital modulations like BPSK and QPSK. The results show the BER performance for different SUI channel models and modulations.
BER Analysis of OFDM Systems with Varying Frequency Offset Factor over AWGN a...rahulmonikasharma
The document analyzes the effect of varying frequency offset on the bit error rate (BER) performance of orthogonal frequency division multiplexing (OFDM) systems over additive white Gaussian noise (AWGN) and Rayleigh channels through simulation. The simulations show that as the frequency offset increases, the BER performance of the OFDM system degrades in both channel conditions due to increased inter-carrier interference (ICI). Higher frequency offset values lead to worse performance degradation. An effective technique is needed to mitigate the impact of frequency offset on OFDM system performance.
WC & LTE 4G Broadband Module 2- 2019 by Prof.Suresha VSURESHA V
This document discusses multicarrier modulation techniques used in LTE, focusing on OFDM, OFDMA, and SC-FDMA. It covers the basics of OFDM including how it divides a high-rate data stream into multiple parallel low-rate substreams to mitigate intersymbol interference. The cyclic prefix is discussed as a guard interval to eliminate intercarrier interference. OFDMA and SC-FDMA are described as incorporating frequency division multiple access into OFDM. The document also reviews spatial diversity and multiplexing techniques used in LTE systems.
IRJET- Orthogonal Frequency Division Multiplexing (OFDM) based Uplink Multipl...IRJET Journal
This document discusses Orthogonal Frequency Division Multiplexing (OFDM) for uplink transmission over different channel conditions. It begins by introducing OFDM and how it splits data across multiple narrowband carriers to mitigate intersymbol interference. It then discusses using QPSK modulation with OFDM. Next, it analyzes OFDM performance over additive white Gaussian noise (AWGN) channels and different fading channels like Rayleigh and Rician fading. It finds that BER decreases with increasing SNR in AWGN channels, and the amount of fading impacts BER in fading channels. Simulation results using MATLAB show the effect of different channels on OFDM signals.
This document analyzes the simulation parameters of a pulse shaping FIR filter for WCDMA. It simulates a square root raised cosine pulse shaping filter in MATLAB Simulink with varying group delay parameters. The simulation measures the number of bits, number of errors, and bit error rate at different group delays. It finds that the bit error rate is minimized at a group delay of 6 symbol periods. The optimal values found are a group delay of 6 and a roll off factor of 0.22.
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.
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
Performance Analysis of MIMO-OFDM System Using QOSTBC Code Structure for M-PSKCSCJournals
This document discusses performance analysis of MIMO-OFDM systems using QOSTBC coding for M-PSK modulation. It proposes a QOSTBC code structure for a 4x4 antenna configuration MIMO-OFDM system. It analyzes the performance of the system in AWGN and Rayleigh channels by evaluating BER versus SNR for different M-PSK modulation schemes and antenna configurations. The proposed MIMO-OFDM system with 4x4 QOSTBC coding is shown to have better performance than other systems in terms of lower BER for a given SNR.
The document describes the simulation of an OFDM system using MATLAB. It discusses key aspects of OFDM including how it divides the frequency selective fading channel into narrow flat subchannels. It also discusses the transmitter and receiver blocks including modulation, channel effects, demodulation and error calculation. The MATLAB code simulates transmission of 256 bits using QAM modulation over an AWGN channel. Results show the transmitted and received OFDM signal spectra and constellation diagrams, validating the simulation.
This report discusses the planning Associate in
nursing the implementation of an OFDM system
in several information module schemes like MQPSK,
M-QAM. First, a short introduction is
provided by explaining the background and the
specification of the project. Then the report deals
with the system model, every block of the OFDM
system is represented (IFFT, FFT, Cyclic prefix,
modulation / reception, Channel estimation, bit
error rate). System design is analyzed. The
transmission techniques, further because the
system parameters for transmission and reception
are explained well. Finally, the results are
provided.
This document summarizes research on reducing peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. It discusses using a companding technique with Gaussian distribution to compress the signal before transmission and decompress it upon reception. The key aspects covered are: applying a compander and decompander with Gaussian distribution parameters at the transmitter and receiver; how the central limit theorem allows the sum of subcarriers to approximate a Gaussian distribution for large numbers; and how this technique reduces PAPR by increasing average power while keeping peak power the same. Performance is analyzed by simulating PAPR and bit error rate with and without companding under different parameters.
This document summarizes a simulation of an IEEE 802.16-2004 OFDM physical layer model in MATLAB. The model includes key parameters like modulation type, bandwidth, SNR, delays, and more. By changing these parameters, their effects on performance metrics like BER are observed. Key findings include higher SNR and larger bandwidth resulting in better performance with more widely spaced constellation points and lower BER. Larger cyclic prefix also improves performance by reducing inter-symbol interference. The document concludes the model is viable for analyzing important WiMAX parameters and their impacts.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
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This document discusses the impact of data mining on business intelligence. It begins by defining business intelligence as using new technologies to quickly respond to changes in the business environment. Data mining is an important part of the business intelligence lifecycle, which includes determining requirements, collecting and analyzing data, generating reports, and measuring performance. Data mining allows businesses to access real-time, accurate data from multiple sources to improve decision making. Using business intelligence and data mining techniques can help businesses become more efficient and make better decisions to increase profits and customer satisfaction. The expected results of applying business intelligence include improved decision making through accurate, timely information to support organizational goals and strategic plans.
This document presents a novel technique for solving the transcendental equations of selective harmonics elimination pulse width modulation (SHEPWM) inverters based on the secant method. The proposed algorithm uses the secant method to simplify the numerical solution of the nonlinear equations and solve them faster compared to other methods. Simulation results validate that the proposed method accurately estimates the switching angles to eliminate specific harmonics from the output voltage waveform and achieves near sinusoidal output current for various modulation indices and numbers of harmonics eliminated.
This document summarizes a research paper that designed and implemented a dual tone multi-frequency (DTMF) based GSM-controlled car security system. The system uses a DTMF decoder and GSM module to allow a car to be remotely controlled and secured from a mobile phone. It works by sending DTMF tones from the phone through calls to the GSM module in the car. The decoder interprets the tones and a microcontroller executes commands to disable the ignition or control other devices. The system was created to improve car security and accessibility through remote monitoring and control with DTMF and GSM technology.
This document presents an algorithm for imperceptibly embedding a DNA-encoded watermark into a color image for authentication purposes. It applies a multi-resolution discrete wavelet transform to decompose the image. The watermark, encoded into DNA nucleotides, is then embedded into the third-level wavelet coefficients through a quantization process. Specifically, the watermark nucleotides are complemented and used to quantize coefficients in the middle frequency band, modifying the coefficients. The watermarked image is reconstructed through inverse wavelet transform. Extraction reverses these steps to recover the watermark without the original image. The algorithm aims to balance imperceptibility and robustness through this wavelet-based, blind watermarking scheme.
1) The document analyzes the dynamic saturation point of a deep-water channel in Shanghai port based on actual traffic data and a ship domain model.
2) A dynamic channel transit capacity model is established that considers factors like channel width, ship density, speed, and reductions due to traffic conditions.
3) Based on AIS data from the channel, the average traffic flow is calculated to be 15.7 ships per hour, resulting in a dynamic saturation of 32.5%, or 43.3% accounting for uneven day/night traffic volumes.
The document summarizes research on the use of earth air tunnels and wind towers as passive solar techniques. Key findings include:
- Earth air tunnels circulate air through underground pipes to take advantage of the stable temperature 4 meters below ground for cooling in summer and heating in winter. Testing showed the technique can reduce ambient temperatures by up to 14 degrees Celsius.
- Wind towers circulate air through tall shafts to cool air entering buildings at night and provide downward airflow of cooled air during the day.
- Experimental testing of an earth air tunnel system over multiple months found maximum temperature reductions of 33% in spring and minimum reductions of 15% in summer.
The document compares the mechanical and physical properties of low density polyethylene (LDPE) thin films and sheets reinforced with graphene nanoparticles. LDPE/graphene thin films were produced via solution casting, while sheets were made by compression molding. Testing showed that the thin films had enhanced tensile strength, lower melt flow index, and higher thermal stability compared to sheets. The tensile strength of thin films increased by up to 160% with 1% graphene, while sheets increased by 70%. Melt flow index decreased more for thin films, indicating higher viscosity. Thin films also showed greater improvement in glass transition temperature. These results demonstrate that processing technique affects the properties of LDPE/graphene nanocomposites.
The document describes improvements made to a friction testing machine. A stepper motor and PLC control system were added to automatically vary the load on friction pairs, replacing the manual method. Tests using the improved machine found that the friction coefficient decreases as the load increases, and that abrasive and adhesive wear increased with higher loads. The improved machine allows more accurate and convenient testing of friction pairs under varying load conditions.
This document summarizes a research article that investigates the steady, two-dimensional Falkner-Skan boundary layer flow over a stationary wedge with momentum and thermal slip boundary conditions. The flow considers a temperature-dependent thermal conductivity in the presence of a porous medium and viscous dissipation. Governing partial differential equations are non-dimensionalized and transformed into ordinary differential equations using similarity transformations. The equations are highly nonlinear and cannot be solved analytically, so a numerical solver is used. Numerical results are presented for the skin friction coefficient, local Nusselt number, velocity and temperature profiles for varying parameters like the Falkner-Skan parameter and Eckert number.
An improvised white board compass was designed and developed to enhance the teaching of geometrical construction concepts in basic technology courses. The compass allows teachers to visually demonstrate geometric concepts and constructions on a white board in an engaging, hands-on manner. It supports constructivist learning principles by enabling students to observe and emulate the teacher. The design process utilized design and development research methodology to test educational theories and validate the practical application of the compass. The improvised compass was found to effectively engage students and improve their performance in learning geometric constructions.
The document describes the design of an energy meter that calculates energy using a one second logic for improved accuracy. The meter samples voltage and current values using an ADC synchronized to the line frequency via PLL. It calculates active and reactive power by averaging the sampled values over each second. The accumulated active power for each second is multiplied by one second to calculate energy, which is accumulated and converted to kWh. Test results showed the meter achieved an error of 0.3%, within the acceptable limit for class 1 meters. Considering energy over longer durations like one second helps reduce percentage error in the calculation.
This document presents a two-stage method for solving fuzzy transportation problems where the costs, supplies, and demands are represented by symmetric trapezoidal fuzzy numbers. In the first stage, the problem is solved to satisfy minimum demand requirements. Remaining supplies are then distributed in the second stage to further minimize costs. A numerical example demonstrates using robust ranking techniques to convert the fuzzy problem into a crisp one, which is then solved using a zero suffix method. The total optimal costs from both stages provide the solution to the original fuzzy transportation problem.
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1. International Journal of Engineering Inventions
ISSN: 2278-7461, www.ijeijournal.com
Volume 1, Issue 3 (September 2012) PP: 06-11
Bit Error Rate of Mobile Wimax (Phy) Under Different
Communication Channels and Modulation Technique
T.Manochandar1, R.Krithika2
1
Department of Electronics and Communication Engineering, VRS College of engineering and technology,
Villupuram- 607 107.TamilNadu
2
Department of Electronics and Communication Engineering, E.S College of engineering and technology,
Villupuram-605 602.TamilNadu
Abstract––Mobile Wimax is a broadband wireless solution that enables the convergence of mobile and fixed broadband
network, through a common wide area broadband radio access technology and flexible network architecture. The
Performance of mobile Wimax under varying channel is one of the interesting research interests. Most of the most
existing systems, based on performance and evaluation under channel condition are limited to AWGN, ITU etc in mobile
Wimax. In this paper the performance of mobile Wimax (PHY layer) under SUI channel models in addition to different
data rates and modulation techniques were analyzed. The simulation covers important performance parameters like Bit
Error Rate and Signal to Noise Ratio.
Keywords––Wimax, BER, SNR, BPSK, OFDMA
I. INTRODUCTION
IEEE802.16e is a global broadband wireless access standard capable of delivering high data rates to fixed users as
well as portable and mobile ones over long distance [1].In mobile Wimax air interface adopts orthogonal frequency division
multiple access (OFDMA) for improved multi-path performance in non-line-of sight (NLOS) environment. Mobile Wimax
extends the OFDM PHY layer to support terminal mobility and multiple–access. The resulting technology is Scalable
OFDMA. Data streams to and from individual users are multiplexed to groups of sub channel on the downlink and uplink.
By adopting Scalable PHY architecture, mobile Wimax is able to support a wide range of bandwidths.
The performance of the WiMAX (Worldwide Interoperability for Microwave Access) can be evaluated by using
the Stanford University Interim (SUI) channel models which has a set of six channels for terrain types [3].With different data
rates, coding schemes and modulation techniques.
The mobile WiMAX standard builds on the principles of OFDM by adopting a Scalable OFDMA-based PHY
layer (SOFDMA) [4]. SOFDMA supports a wide range of operating bandwidths to flexibly address the need for various
spectrum allocation and application requirements.
The simulation done in the paper covers important performance such as Bit Error Rate and Signal to Noise Ratio.
II. WIMAX PHYSICAL LAYER
This project deals with the performances of Bit Error Rate and Signal to Noise Ratio in mobile WiMAX physical
layer. The block diagram of the physical layer of mobile WiMAX diagram is given in Figure 1. The transferring of data or
receiving the data is done through the physical layer of WiMAX. So the uplink and the downlink of the message were done
on the physical layer of WiMAX. There are three levels in the physical layer of mobile WiMAX physical layer are
Bit level processing
OFDM symbol level processing
Digital IF processing
Each levels of physical layer of WiMAX consist of certain processes for transferring the data at uplink region and
receiving of data at downlink region consists of encoder, decoder, symbol mapper and randomizer etc., Every processes were
done in order to improve the performance of the mobility condition of mobile wimax. In this paper the performance was
analyzed by the signal to noise ratio and the bit error rate
6
2. Bit Error Rate Of Mobile Wimax (Phy) Under Different Communication…
.
Figure: 1. Block Diagram of Wimax Physical Layer
Table.1 Parameter of mobile wimax physical layer
Parameter Value
FFT size 128 512 1024 2048
Channel 1.25 5 10 20
Bandwidth(MHz)
Subcarrier Frequency
spacing 10.94
(KHz)
Useful Symbol Period
91.4
Guard Time 1/32,1/8,1/6,1/4
III. CHANNEL
The medium between the transmitting antenna and the receiving antenna is said to be the channel. The profile of
received signal can be obtained from that of the transmitted signal, if we have a model of the medium between the two. The
model of the medium is called channel model.
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3. Bit Error Rate Of Mobile Wimax (Phy) Under Different Communication…
Y (f) =X (f) H (f) +n (f)
Where,
Y (f) ->output signal
H (f) ->channel response
X (f) ->input signal
A. Stanford University Interim (SUI) Channel Models:
It is a set of six channel models representing three terrain types and a variety of Doppler spreads, delay spread and
mainly the line-of-sight/non-line-of-site conditions that are typical of the continental. The terrain type A, B, C is same
as those defined in Erceg model [10]. The multipath fading is modeled as a tapped delay line with 3 taps with non-uniform
delays. The gain associated with each tap is characterized by a Rician Distribution and the maximum Doppler frequency.
In a multipath environment, the received power r has a Rician distribution, whose Pdf is given by:
Pdf(r)=r/σ2e(-r2/2σ2) 0≤r≤∞
A is zero if there is no LOS component and the pdf of the power becomes
Pdf(r)=r/σ2e[-frac2+A2σ2]Io(rA/σ2) 0 ≤ r ≤ ∞
This is also known as Raleigh distribution.
The ratio K=A2/ (2σ2) in the Rician case represents the ratio of LOS component to NLOS component and is called the "K-
Factor" or "Rician Factor."
The general structure for the SUI channel model is as shown below in figure. This structure is for Multiple Input
Multiple Output (MIMO) channels and includes other configurations like Single Input Single Output (SISO) and Single
Input Multiple Output (SIMO) as subsets.
Tapped Output
Delay Mixing
Input
Line Matrix
Mixing Matrix
Matrix
Figure 2.SUI Channel Model
Power Distribution For each tap a set of complex zero-mean Gaussian distributed numbers is generated with a
variance of 0.5 for the real and imaginary part, so that the total average power of this distribution is 1. This yields a
normalized Rayleigh distribution (equivalent to Rice with K=0) for the magnitude of the complex coefficients. If a Rician
distribution (K>0 implied) is needed, a constant path component m is added to the Rayleigh set of coefficients. The ratio of
powers between this constant part and the Rayleigh (variable) part is specified by the K-factor. For this general case, we
show how to distribute the power correctly by first stating the total power P of each tap:
P=|m2|+σ2
Where m is the complex constant and σ2 the variance of the complex Gaussian set. Second, the ratio of powers is K=m2/|σ2|.
Table 2: Terrain type and Doppler spread for SUI channel model
Channel Terrain Doppler Spread LOS
Type spread
SUI-1 C Low Low High
SUI-2 C Low Low High
SUI-3 B Low Low Low
SUI-4 B High Moderate Low
SUI-5 A Low High Low
SUI-6 A High High High
8
4. Bit Error Rate Of Mobile Wimax (Phy) Under Different Communication…
In the SUI channel model, parameter for the SUI 1 and SUI 2 channel model has been tabulated in 3 and 4
respectively for the reference. BER performance is evaluated in this channel models. Depending on the performance
parameter for the SUI channel, the performances of wimax physical layer are evaluated through the performance graph.
.
For a 300 antenna beam width, 2.3 times smaller RMS delay spread is used when compared to an omnidirectional
antenna RMS delay spread. Consequently, the 2nd tap power is attenuated additional 6 dB and the 3rd tap power is
attenuated additional 12 dB (effect of antenna pattern, delays remain the same). The simulation results for all the six
channels are evaluated. The above experiments are done using the simulation in Matlab communication tool box.
IV. SIMULATION RESULTS
The output for the performance of mobile WiMAX was estimated by the BER and the SNR plot using the
MATLAB coding with BPSK modulation. The bandwidth used in the experiment was 3.5 MHz
9
5. Bit Error Rate Of Mobile Wimax (Phy) Under Different Communication…
Figure3.BER curve for BPSK modulation
The output for the performance of mobile WiMAX was estimated by the Bit Error Rate and the Signal to Noise
Ratio plot using the MATLAB coding with Quadrature Phase Shift Keying modulation technique is given below in figure 4.
Figure 4. BER curve for QPSK modulation
The output for the performance of mobile WiMAX was estimated by the BER and the SNR plot using the
MATLAB coding with 16QAM modulation. It is illustrated in the figure5.
Figure5. BER curve for 16QAM modulation
10
6. Bit Error Rate Of Mobile Wimax (Phy) Under Different Communication…
The output for the performance of mobile Wimax was estimated by the BER and the SNR plot using the
MATLAB coding with 64QAM modulation and graphical illustration done as in figure 6.
Figure6. BER curve for 64QAM modulation
V. CONCLUSION
In this paper, the performance of mobile WIMAX physical layer for OFDMA on different channel condition
assisted by Mobile IP(Internet protocol) for mobility management was analyzed. The analysis demonstrated that the
modulation and coding rate had a greater impact on the relative performance between the different SUI channel conditions.
The performance was analyzed under SUI channel models with different modulation techniques for mobility management. It
is found from the performance graphs that SUI channel 5 and 6 performs better than the conventional ones.
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