scholarly journals Performance Analysis of Associate Radix-2, Radix- 4 and Radix-8 based FFT using Folding Technique

2021 ◽  
Vol 9 (10) ◽  
pp. 1489-1494
Author(s):  
Pankaj Kumar Singh
Keyword(s):  
Mobile Communications ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
New Technology ◽  
Data Communication ◽  
Multipath Fading ◽  
Ieee 802.16E ◽  
Multipath Fading Channel ◽  
Ieee 802.11A

Abstract : In recent years, as a result of advancing VLSI technology, Orthogonal Frequency Division Multiplexing (OFDM) has received a great deal of attention and has been adopted in many new generation wideband data communication systems such as IEEE 802.11a, IEEE 802.16e, HiPerLAN/2, Digital Audio/Video Broadcasting (DAB/DVB), and for 4G Radio mobile communications. This is because of its high bandwidth efficiency as the use of orthogonal waveforms with overlapping spectra. The immunity to multipath fading channel and the capability for parallel signal processing make it a promising candidate for the next generation mobile communication systems. The modulation and demodulation of OFDM based communication systems can be efficiently implemented with an FFT and IFFT, which has made the FFT valuable for those communication systems. The complexity of an OFDM system highly depends upon the computation of Fast Fourier Transform (FFT) algorithm. With the advent of new technology in the fields of VLSI and communication, there is also an ever growing demand for high speed processing and low area design. It is also a well-known fact that the multiplier unit forms an integral part of processor design. Due to this regard, high speed multiplier architectures become the need of the day.

scholarly journals Development of mobile communication systems for high-speed railway

2021 ◽  
Vol 1 (1) ◽  
pp. 29-34
Author(s):  
Nedžad Branković ◽  
Aida Kalem ◽  
Adisa Medić
Keyword(s):  
Mobile Communication ◽  
Mobile Communications ◽  
Traffic Management ◽  
Communication Systems ◽  
High Speed ◽  
Data Communication ◽  
Mobile Communication Systems ◽  
Transport Services ◽  
Traffic Management System ◽  
Set Up

Development of high-speed railways set up challenges for new communication technologies. With the increase in speed, new requirements for communication systems have emerged that HSR requires greater reliability, capacity and shorter response time for efficient and safe operations. Mobile communication systems are crucial for the competitiveness of the railway industry and therefore have become one of the priorities addressed by the participants in the railway system to take advantage of technological opportunities to improve operational processes and the quality of provided transport services. The European Rail Traffic Management System (ERTMS) uses the Global System for Mobile Communications for Railways (GSM-R) for voice and data communication to communicate between trains and control centers. The International Railway Union is exploring new ways of communicating for high-speed railways because as speed increases this system becomes unreliable in information transmission. This paperwork presents an analysis of the evolution of communications on European railways since the usage of GSM-R. In addition, an overview of the various alternative solutions proposed during the time (LTE-R, Future Railway Mobile Communication System) as possible successors to GSM-R technology is given.

Improved Clipping Technique for PAPR Reduction in OFDM

2014 ◽  
Vol 548-549 ◽  
pp. 1420-1423
Author(s):  
M.R. Anjum ◽  
M.A. Shaheen ◽  
Farhan Manzoor ◽  
Mussa A. Dida
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Average Power ◽  
Multipath Fading ◽  
Papr Reduction ◽  
Major Drawback ◽  
Multipath Fading Channel ◽  
Peak Magnitude ◽  
Ofdm Signal ◽  
Clipping Technique

Multicarrier modulation technique also known as Orthogonal Frequency Division Multiplexing (OFDM) is considered to be the most rapidly growing technique for 4th Generation wireless communication system. Due to its high speed data rate and its ability of multipath fading channel robustness. OFDM becomes an attractive technique and it is widely adopted in many wireless communications system. OFDM signal carries its major drawback of high Peak to Average Power Ratio (PAPR) problem. Out of band radiation and in band distortion produced due to its high PAPR. Mobile phone communication suffer severe drawback during its amplification. When OFDM employed a non linear Power Amplifier (PA), it produces the fluctuation in amplitude of OFDM signal. This paper discusses the method to overcome PAPR in terms of its performance by using improved clipping technique for PAPR reduction. This method is easy to implement and reduces the amount of PAPR by clipping the peak of the maximum power signal. We present an improved method for PARR reduction for reducing peak magnitude of OFDM signal. This scheme simultaneously minimizes the peak magnitude of PAPR in OFDM signal.

Improving OFDM Carrier Frequency Synchronization Using Cyclic Prefix

2013 ◽  
Vol 411-414 ◽  
pp. 779-783
Author(s):  
Ju Peng Zhang ◽  
Ming Jiang Wang
Keyword(s):  
Carrier Frequency ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Multipath Fading ◽  
Cyclic Prefix ◽  
Packet Transmission ◽  
Frequency Synchronization ◽  
Carrier Frequency Synchronization ◽  
Improved Algorithm

Orthogonal Frequency Division Multiplexing (OFDM) is the key technology of high speed communication systems which are widely used today. Small carrier frequency offset can make OFDM system performance fell sharply. So it needs very effective carrier frequency synchronization to make sure that the system works perfect. Seen from a large number of simulations, typical algorithm requires strict symbol timing. According to this characteristic, we proposed an improved carrier frequency synchronization algorithm using cyclic prefix. The improved algorithm can achieve better performance than typical algorithm in multipath fading channel. The precision of the improved algorithm under the same Signal Noise Ratio (SNR) is about 3 orders of magnitude higher than typical algorithm. We found that improved algorithm has more excellent performance in burst packet transmission mode.

BER Improvement in OFDM Systems Using Wavelet Transform Based on Kalman Filter

2020 ◽  
pp. 102-124
Author(s):  
Sajjan Singh
Keyword(s):  
Kalman Filter ◽  
Wavelet Transform ◽  
Fading Channels ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Performance Enhancement ◽  
Average Power ◽  
Discrete Wavelet ◽  
Rate Analysis

Orthogonal frequency division multiplexing (OFDM) is an efficient method of data transmission for high speed communication systems over multipath fading channels. However, the peak-to-average power ratio (PAPR) is a major drawback of multicarrier transmission systems such as OFDM is the high sensitivity of frequency offset. The bit error rate analysis (BER) of discrete wavelet transform (DWT)-OFDM system is compared with conventional fast Fourier transform (FFT)-OFDMA system in order to ensure that wavelet transform based OFDMA transmission gives better improvement to combat ICI than FFT-based OFDMA transmission and hence improvement in BER. Wavelet transform is applied together with OFDM technology in order to improve performance enhancement. In the proposed system, a Kalman filter has been used in order to improve BER by minimizing the effect of ICI and noise. The obtained results from the proposed system simulation showed acceptable BER performance at standard SNR.

An Improved Data-Aided Symbol Timing Algorithm for OFDM Systems

2011 ◽  
Vol 403-408 ◽  
pp. 1568-1571
Author(s):  
Xiao Yan Zhao
Keyword(s):  
Fading Channel ◽  
Orthogonal Frequency Division Multiplexing ◽  
Signal To Noise Ratio ◽  
Multipath Fading ◽  
Ofdm Systems ◽  
Multipath Fading Channel ◽  
Symbol Synchronization ◽  
Timing Errors ◽  
Symbol Timing ◽  
Training Symbol

Synchronization is very important to orthogonal frequency division multiplexing (OFDM) systems. Taking aim at the problem that the timing inaccuracy of the S&C method and the indistinct peak of the timing metric produced by Park method under the low signal-to-noise ratio (SNR) and fading channel, a new symbol synchronization algorithm based on the training symbol is proposed in this paper. The new algorithm exploits the training symbol proposed by S&C to correlate the received signal with the known training symbol again at the receiving end to identify the start point of the OFDM symbol. The result of the simulation shows that the proposed method’s timing metric is of the impulse-shaped peak under the condition of the lower SNR and multipath fading channel, and has smaller timing errors compared with the conventional method in terms of mean-square error (MSE) of the timing estimator.

scholarly journals Palm Date Leaf Clipping: A New Method to Reduce PAPR in OFDM Systems

Information ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 190 ◽  
Author(s):  
Brahim Bakkas ◽  
Reda Benkhouya ◽  
Idriss Chana ◽  
Hussain Ben-Azza
Keyword(s):  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Average Power ◽  
Papr Reduction ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Leaf Clipping ◽  
Hyperbolic Cosine ◽  
Transmitted Signal

Orthogonal frequency division multiplexing (OFDM) is the key technology used in high-speed communication systems. One of the major drawbacks of OFDM systems is the high peak-to-average power ratio (PAPR) of the transmitted signal. The transmitted signal with a high PAPR requires a very large linear range of the Power Amplifier (PA) on the transmitter side. In this paper, we propose and study a new clipping method named Palm Clipping (Palm date leaf) based on hyperbolic cosine. To evaluate and analyze its performance in terms of the PAPR and Bit Error Rate (BER), we performed some computer simulations by varying the Clipping Ratio (CR) and modulation schemes. The obtained results show that it is possible to achieve a gain of between 7 and 9 dB in terms of PAPR reduction depending on the type of modulation. In addition, comparison with several techniques in terms of PAPR and BER shows that our method is a strong alternative that can be adopted as a PAPR reduction technique for OFDM-based communication systems.

scholarly journals Channel Estimation in DCT-Based OFDM

2014 ◽  
Vol 2014 ◽  
pp. 1-6
Author(s):  
Yulin Wang ◽  
Gengxin Zhang ◽  
Zhidong Xie ◽  
Jing Hu
Keyword(s):  
Channel Estimation ◽  
Orthogonal Frequency Division Multiplexing ◽  
Multipath Fading ◽  
Wireless Channel ◽  
Least Square ◽  
System Throughput ◽  
Multipath Fading Channel ◽  
Channel Response ◽  
Coherent Demodulation ◽  
And Performance

This paper derives the channel estimation of a discrete cosine transform- (DCT-) based orthogonal frequency-division multiplexing (OFDM) system over a frequency-selective multipath fading channel. Channel estimation has been proved to improve system throughput and performance by allowing for coherent demodulation. Pilot-aided methods are traditionally used to learn the channel response. Least square (LS) and mean square error estimators (MMSE) are investigated. We also study a compressed sensing (CS) based channel estimation, which takes the sparse property of wireless channel into account. Simulation results have shown that the CS based channel estimation is expected to have better performance than LS. However MMSE can achieve optimal performance because of prior knowledge of the channel statistic.

ELECTRONICS FOR HIGH SPEED, BURST MODE OPTICAL COMMUNICATIONS

1990 ◽  
Vol 01 (03n04) ◽  
pp. 223-243 ◽  
Author(s):  
R.G. SWARTZ ◽  
Y. OTA
Keyword(s):  
Communication Systems ◽  
High Speed ◽  
Data Communication ◽  
Optical Fiber Communication ◽  
Digital Data ◽  
Optical Data ◽  
Data Link ◽  
Fiber Communication ◽  
Burst Mode ◽  
Multiple Channel

Electronics for burst mode data communication over an optical data link will contribute to wider acceptance of photonic technology. This paper describes the concepts and difficulties inherent in burst mode optical communication systems, and proposes a new solution employing an ultra-high speed, high accuracy peak detector. Sensitivity penalties associated with this technique are reviewed. The method was implemented in an optical receiver with dc to 500 Mb/s operation, and at 200 Mb/s, demonstrates an isolated pulse sensitivity of −29.5 dBm, and pulse width distortion less than lns. An example application, the Multiple channel Optical Data LINK (MODLINK), is described: a fully dc-coupled, 12 parallel channel digital data link system designed for high speed optical fiber communication at bit rates ranging from dc to 200 Mb/s per channel, applicable at distances of centimeters to over 3 km.

scholarly journals ICI Cancellation in OFDM Systems by Frequency Offset Reduction

2014 ◽  
Vol 513-517 ◽  
pp. 3987-3991
Author(s):  
Naveed Ur Rehman ◽  
Lei Zhang ◽  
Muhammad Zahid Hammad ◽  
Emmanuel Anania Mwangosi
Keyword(s):  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Video Data ◽  
Modulation Scheme ◽  
Ofdm Systems ◽  
Receiver Side ◽  
High Data ◽  
Redundant Data ◽  
Wide Range

The rapid growth within the field of digital communication during the recent years expanded the need for high-speed data transmission to support a wide range of services such as: video, data and voice in wireless communication systems, etc. Orthogonal frequency division multiplexing (OFDM) and a multicarrier modulation scheme are employed to achieve the high data rates. Since OFDM is very much sensitive to carrier frequency offsets, which cause the Inter-carrier Interference (ICI) leads to mitigation of this ICI is necessary. The objectives of this paper are to, proposed an efficient ICI self-cancellation scheme to mitigate the effect of ICI on OFDM systems. For this purpose, a redundant data is transmitted onto adjacent sub-carriers such that the ICI between adjacent sub-carriers cancels out at the receiver side. One data symbol is modulated into a group of adjacent sub carriers with a group of weighting coefficients. At the receiver side, the received signals are linearly combined on these sub carriers with proposed coefficients. The residual ICI contained in the received signals can then be further reduced. This study provides significant carrier-to-interference power ratio (CIR) improvement, which has been studied theoretically and supported by simulations. Since no channel equalization is required to reduce ICI, so the proposed scheme doesnt increase the system complexity.

scholarly journals PAPR reduction in OFDM system for DVB-S2

2020 ◽  
Vol 17 (1) ◽  
pp. 317
Author(s):  
Zainab M Abid ◽  
Awatif A Jaffaar ◽  
Suha Q Hadi
Keyword(s):  
Fading Channels ◽  
Power Amplifier ◽  
Spectral Efficiency ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Average Power ◽  
Multipath Fading ◽  
Papr Reduction ◽  
Major Drawback ◽  
Ofdm Signal

<p>A special form of multicarrier modulation is Orthogonal Frequency Division Multiplexing (OFDM) which is offer high spectral efficiency for high speed data transmission through multipath fading channels. Many advantages can be achieved by using OFDM in addition to spectral efficiency like its robustness against intersymbol interference and multipath effect. One of a major drawback of OFDM is high Peak-to-Average Power Ratio (PAPR) of the transmitted signal which leads to a distortion in the power amplifier and causes decreasing the efficiency of power amplifier. To reduce PAPR of OFDM signal many of promising solutions have been proposed and implemented. In this paper, a joint Low Density Parity Check code (LDPC), Discrete Cosine Transform (DCT) and μ-law companding is proposed to reduce PAPR of OFDM signal at transmitter. Comparison of these PAPR reduction techniques is done based on CCDF performance of the system.</p>

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