Comparative Study of Digital Modulation Techniques in WIMAX

The migration to 4G networks will bring a new level of expectation to wireless communications. As after digital wireless revolution made mobile phones available for everyone, the higher speeds and packet delivery of 4G networks will make high quality multimedia available everywhere. The key to achieving this higher level of service delivery is a new air interface. Orthogonal Frequency Division Multiplexing (OFDM) is an alternative wireless modulation technology to CDMA. OFDM has the potential to surpass the capacity of CDMA systems and provide the wireless access method for 4G systems. OFDM is a digital modulation and multiplexing technique. In this paper, we have discussed various digital modulation techniques such as BPSK (2bits), QPSK (4 bits), 8-PSK and 16-PSK. We have designed simulation environment in MATLAB with various configurations of OFDM technique.

Journal of Electrical Engineering, Electronics, Control and Computer Science, 2021

At the present era of communication technology, every user wants a communication system that has higher data transmission capability and reliability. Orthogonal Frequency Division Multiplexing (OFDM) is a frequency division multiplexed multi carrier transmission method and each multiplexed signal is orthogonal to each other. This technology is known as core technology of the new generation wireless mobile communication systems. This technology has higher data transmission capability and reliability as well as has the ability to combat frequency selective fading or narrowband interference while maintaining high spectrum utilization. The aim of this paper is to analyze the performance of the OFDM technology using different modulation techniques. This paper is mainly focused on the calculation of the Bit Error Rate (BER) to analyze the performance of OFDM systems. In this paper, we considered BPSK, QPSK, 64-QAM, 128-QAM and 256-QAM modulation techniques. All the simulations has been accomplished by using the MATLAB framework.

Communications on Applied Electronics, 2016

OFDM is a multicarrier technique for transmission, which divides the available spectrum into many carriers with each one of them being modulated by a data stream of low rate. OFDM is similar to FDMA in the sense that the multiple user access is achieved by further dividing the available bandwidth to multiple channels. These sub channels are then allocated to the users. But in OFDM, the spectrum is used much more efficiently by spacing the channels much close to one another. This is achieved by making all the carriers orthogonal to one another, preventing interference between these carriers. The digital data in serial form to be transmitted is split into different data streams, and each one of them is modulated by a separate carrier in the allotted bandwidth. The modulation done can be any one of the forms of modulation applied to digital data, but the most commonly used are quadrature phase shift keying (QPSK), and quadrature amplitude modulation (QAM). When these modulators are used, their outputs are summed linearly, and the output signal is sent to the channel. In this paper we will analyze the performance of different modulation techniques in AWGN channel. We conclude that a different modulation scheme has different bit error rate.

IOSR Journal of Engineering, 2012

The telecommunication industries insisted on new technology with high transmission abilities standardized by IEEE 802.16 also referred as WiMAX .It has two patterns fixed (802.16d-2004) and mobile (802.16d-2005) which are based on OFDM. This paper is about study and implementation of Convolutional coded WiMAX system comparing different modulation schemes such as BPSK and QAM . The performance has been concluded based on BER and SNR through MATLAB Simulation.

2016

Orthogonal frequency division multiplexing (OFDM) is a type of multicarrier modulation technique in which available bandwidth is divided into narrow bands at different frequencies. It is used to compress a large amount of data into a small amount of bandwidth. This is possible by dividing a large amount of data into smaller parts, then sending that data simultaneously over a number of frequencies. OFDM allows a large amount of data to be transmitted quickly and reliably, with a minimum of loss or interference. As OFDM is used in various applications like Wi-Fi, 4G, DAB & WiMax, so its performance is an important factor and for this Bit Error ratio (BER) is calculated.This paper deals with the comparison between DWT based OFDM and FFT based OFDM for various digital modulation techniques and channel coding in terms of Bit error rate calculation. Simulation results shows that FFT based OFDM have better results as compared to DWT based OFDM.

The next generation wireless communications systems need to be of a higher standard in order to provide the customers with the multitude of high quality services they demand. Orthogonal frequency division multiplexing (OFDM) is a key technique for achieving high data rates and spectral efficiency requirements for wireless communication systems OFDM is becoming the chosen modulation technique for wireless communications. OFDM can provide large data rates with sufficient robustness to radio channel impairments. The purpose of this paper is to implement the basic processing involved in the transmission and reception of an OFDM technique. The implementation of OFDM is done in MATLAB.

The demand for high-speed mobile wireless communications is rapidly growing. Orthogonal Frequency Division Multiplexing (OFDM) technology promises to be a key technique for achieving the high data capacity and spectral efficiency requirements for wireless communication systems in the near future. An Orthogonal Frequency Division Multiplexing (OFDM) scheme offers high spectral efficiency and better resistance to fading environments. In OFDM the data is modulated using multiple numbers of sub-carriers that are orthogonal to each other because of which the problems associated with other modulation schemes such as Inter Symbol Interference (ISI) and Inter Carrier Interference (ICI) is reduced. This paper deals with the analysis of OFDM System utilizing different modulation techniques over Rayleigh, Rician and Additive White Gaussian Noise (AWGN) fading environments with the use of pilot aided arrangement and finally the results are conveyed. The aim of this thesis is to provide practical solutions for OFDM communication system by showing its better performance on different channel using different modulation technique. We applied different channel like AWGN, Rayleigh and Rician over OFDM system. We analyzed the performance of OFDM system regarding different channel. We analyzed the performance and showed the most suitable channel for OFDM communication system. Moreover, we also applied different modulation scheme over OFDM system to show which modulation technique is more efficient for OFDM system. Here we used BPSK, QPSK, 16-QAM and 64-QAM modulation technique. From our experiment we found that, among AWGN & the fading channels (Rayleigh & Rician), AWGN channel has less BER and P(e) than others. So we can say that, for OFDM system, AWGN channel is most suitable. We also found that, in all environments BPSK shows better performance than QPSK, 16QAM & 64QAM. When modulation level increased, corresponding BER & Probability of error P(e) also increased.

The Orthogonal Frequency Division Multiplexing (OFDM) is a practical application of both amplitude and phase modulation scheme and has taking its place in Multiplexing Techniques where a number of independent message signal are at the same time transmitted over a single channel. OFDM is beneficial in transmission with high data rate and better performance. High data rates are achieved by the use of multiple carriers and performance improvement. This paper is based on the QPSK and QAM of Different Modulation order. The performance Evaluation is done using the Bit Error Rate (BER) Against the Signal to Noise Ratio (SNR) parameters which shows a low BER to High SNR. At the end of the work, it was found out that the QPSK has more better performance in OFDM system than the QAM. QPSK has lower BER than the QAM in AWGN, Rayleigh and Rician channel. The performance of QPSK in OFDM is better than the QAM in the OFDM system. The simulation was done using MATLAB/SIMULINK. 1. Introduction All electrical signals exist in continuous wave nature at a given time. Analog communication was the order of the day until recently, a digital form of communication has replaced it due to significant advantages over the analog means of communication. The most important features are the digital modulation techniques adopted by the digital communication systems. Some of the advantages of the techniques includes greater noise immunity and its robust channel impairment, easier multiplexing of various forms of information, accommodation of larger amount of digital error control codes with detection and correction transmission errors and implementation of digital modulation and demodulation scheme and techniques. The type of MODEM adopted depends largely on quality factors such as provision of low bit error rate at low received signal to noise ratio, good performance in an interference, multipath and fading environments, minimum bandwidth occupation and lastly easy and probably cost effective in implementation. This paper in based on BER and SNR analysis using the Digital Communication M-array Modulation Scheme such as PSK and QAM. The binary scheme of a digital data consists of only two symbols i.e. 1 and 0. The distinct waveform known as pulse is assign to these two symbols and transmitted over a channel and detected at the receiving end after converting it back to binary data. In an M-array scheme, a symbol consists of more than one binary digits of either 0 and 1 or both. OFDM as a transmission scheme is adopted by the broadband radio systems and its current used in a well-known standard IEEE 802.16 hence the part which determines the performance in a combination of the dynamic sub-carrier allocation, transmission power allotment, and adaptive modulation (Sivanagaruju & Siddiah, 2014). OFDM is beneficial in transmission with high data rate and better performance. High data rates are achieved by the use of multiple carriers and performance improvement caused by interference ISI which disports the expected signal (Mousumi et al. 2014). Other benefits include increase in spectral efficiency and also minimizes multipath distortion. In this paper, a total number of 128 subcarriers is used at a cyclic prefix of 32. The Maximum bit error is at 100 at 1e7 maximum number of errors. OFDM baseband signal is typically the sum of number of orthogonal sub-carriers, of which each subcarrier is modulated independently by its own data either QAM or PSK. As the name implies, simultaneous transmission is allowed without interference on a lot of sub-carrier from each other. The simplest form of PSK in the binary scheme BPSK. Though the QPSK will be used in this evaluation in detail. The BPSK like QAM overlap without interference other form of PSK is QPSK (Quadrature phase shift keying). QPSK is often used in the evaluation of the Bit Error rate (BER) due to its improved spectral efficiency requirement and for a given bit rate 1/T b, a QPSK system requires just half the bandwidth required for a BPSK system. Hence, QPSK is bandwidth efficient. The QPSK uses the points constellation diagram. QPSK encodes two bits per symbol. In this paper, QAM and PSK will be used in the analysis of the BER as they modulate both phase modulation and

IJRET, 2012

The migration to 4G networks will bring a new level of expectation to wireless communications. As after digital wireless revolution made mobile phones available for everyone, the higher speeds and packet delivery of 4G networks will make high quality multimedia available everywhere. The key to achieving this higher level of service delivery is a new air interface, OFDM, which is in turn enabled by the high level of performance. OFDM provides a robust signal that requires relatively little power yet uses bandwidth very efficiently. Carriers will benefit from greater flexibility by using OFDM, since in the same spectrum they will be able to offer more channels, including higher ‘bandwidth channels, with more types of services. Currently these systems are still being defined and prototyped. Achieving higher data rates requires OFDM systems to make more efficient use of the bandwidth than CDMA systems. One method of achieving this higher efficiency is through the use of higher order modulation. In this paper we have compared two digital modulation techniques 32QAM and 64QAM used for digital transmission of data. Our main objective to develop this configuration is to compare the performance of each modulation techniques. Comparison is done by Bit Error Rate analysis of both modulation techniques. We have developed existing configurations and improved them with high quality senders and receivers using MATLAB technology. In this paper we have also considered how OFDM can improve the real time video streaming over the wireless network. We have considered the problem of multiuser video streaming over OFDM. OFDM is a multi carrier modulation. The growing interest in Multicarrier Transmission by researchers and product developers motivated us to propose this topic for a special issue of Wireless Video transmission and Communications.

Communications on Applied Electronics, 2015

Orthogonal frequency division multiplexing (OFDM) is a form of digital modulation used in a wide array of communication systems. This paper presents a comprehensive performance analysis of orthogonal frequency division multiplexing system. We investigate the basic principle of OFDM system and through computer simulation we present the Bit error rate(BER) and peak-to-average power ratio(PAPR) of OFDM system for different modulation techniques.