scholarly journals Frame Synchronization for the DTMB Systems with the Multiple-Antenna Receivers

2012 ◽  
Vol 6-7 ◽  
pp. 434-438
Author(s):  
Zi Wei Zheng
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Orthogonal Frequency Division Multiplexing ◽  
Wide Band ◽  
Multipath Fading ◽  
Spectrum Efficiency ◽  
Digital Television ◽  
Multiple Antenna ◽  
Frame Synchronization ◽  
Receiver System

Faced with the challenges of modern communication, high data throughput requirements, extensive research has been paid to broadband modulation. The multi-carrier modulation is one of the most important wide band modulation techniques. Orthogonal frequency division multiplexing (OFDM) is an effective blow to the broadcast channel multipath fading and high bit rate transmission multi-carrier modulation technology of wireless channels, it is widely used in modern digital television terrestrial broadcasting (DTTB) system to support performance bandwidth-efficient multimedia services with the aid of inverse fast Fourier transform and fast Fourier transform operation. Multiple-antenna transmitter and receiver technology allows several times to achieve data transmission rates and spectrum efficiency and the use of multiple transmit antennas and multiple receive antennas through spatial processing. The Digital Terrestrial Multimedia Broadcasting (DTMB) system with the multiple-antenna receiver is considered in this paper. Digital Terrestrial Multimedia Broadcasting (DTMB) has three kinds of Frame Head mode with PN420/PN595/PN945 as training sequences for the time domain synchronous OFDM (TDS-OFDM). At the receiver side with multiple antennas, Frame Head mode detection should be done. In this paper, the frame synchronization scheme is proposed for the DTMB systems with the multiple-antenna receiver. System performance studies under different channel situations are used to verify the efficiency of the proposed scheme for the DTMB systems with the multiple-antenna receiver.

scholarly journals Iterative Channel Estimation Scheme for the WLAN Systems with the Multiple-Antenna Receivers

2012 ◽  
Vol 6-7 ◽  
pp. 871-875
Author(s):  
Zi Wei Zheng
Keyword(s):  
Fourier Transform ◽  
Channel Estimation ◽  
Fast Fourier Transform ◽  
Orthogonal Frequency Division Multiplexing ◽  
Multipath Fading ◽  
Spectrum Efficiency ◽  
Frequency Division Multiplexing ◽  
Multiple Antenna ◽  
Frequency Division ◽  
Estimation Scheme

Alleviate the multipath delay spread and suitable for broadband transmission efficiency, orthogonal frequency division multiplexing wireless local area network (WLAN) is widely used to assist inverse fast Fourier transform and fast Fourier transform operation domain. Orthogonal frequency division multiplexing is a blow to the broadcast channel multipath fading and high data throughput, transmission, wireless fading channel method, which is widely used to support high performance bandwidth-efficient wireless multimedia services. Several times in the transmitter and receiver antenna technology allows data transfer rate and spectrum efficiency and the use of multiple transmit antennas and multiple receive antennas through spatial processing. High-precision channel estimation scheme is very important wideband multi-carrier orthogonal frequency complex WLAN systems use multiple antenna receiver based division of labor and the overall multi-carrier orthogonal frequency multiplexing division of performance-based WLAN system is to crucial antenna to receive the symbol error rate. In this article, the iterative channel estimation scheme proposed multi-carrier orthogonal frequency division multiplexed using multiple antennas receiver-based WLAN system.

scholarly journals Iterative Channel Estimation for the Chinese Digital Television Terrestrial Broadcasting Systems with the Multiple-Antenna Receivers

2012 ◽  
Vol 6-7 ◽  
pp. 439-444
Author(s):  
Zi Wei Zheng
Keyword(s):  
Fourier Transform ◽  
Channel Estimation ◽  
Fast Fourier Transform ◽  
Orthogonal Frequency Division Multiplexing ◽  
Multipath Fading ◽  
Wireless Channel ◽  
Digital Television ◽  
Frequency Division Multiplexing ◽  
Multiple Antenna ◽  
Frequency Division

Orthogonal frequency division multiplexing is an effective against multipath fading and high data throughput wireless channel transmission technology. Assistance with the inverse fast Fourier transform and fast Fourier transform operation, orthogonal frequency division multiplexing modulation and demodulation operations of the system convenient and convenient hardware implementation, orthogonal frequency division multiplexing, so in the modern digital television terrestrial broadcasting the system is widely used to support high performance bandwidth-efficient multimedia services. Broadband multi-carrier orthogonal frequency division multiplexing with multi-antenna and multi-antenna receiving system, to increase the diversity gain and improve the capacity of the system in different multipath fading channel. Accurate channel estimation in a simple channel equalization and decoding of broadband multi-carrier orthogonal frequency division multiple-antenna receiver and channel estimation accuracy and multiplexing system is very important, is the key to the performance of the overall broadband multi-carrier orthogonal frequency division multiplexing system in the multi-antenna receiver bit error rate. In this paper, iterative channel estimation to plan for digital terrestrial television broadcasting broadband multi-carrier orthogonal frequency division multiple antenna receiver multiplexing system proposal.

Symbol Synchronization for OFDM Receivers with FFT Transport Delay Compensation

2015 ◽  
Vol 24 (05) ◽  
pp. 1550076
Author(s):  
Diego Pinto Dos Santos ◽  
Candice Müller ◽  
Fabio D'Agostini ◽  
Maria Cristina F. De Castro ◽  
Fernando C. De Castro
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Orthogonal Frequency Division Multiplexing ◽  
Time Synchronization ◽  
Smith Predictor ◽  
Initial Time ◽  
Digital Television ◽  
Television System ◽  
Loop Control ◽  
Phase Rotation

This paper proposes a new blind approach for time synchronization of orthogonal frequency division multiplexing (OFDM) receivers (RX). It is largely known that the OFDM technique has been successfully applied to a wide variety of digital communications systems over the past several years — IEEE 802.16 WiMax, 3GPP-LTE, IEEE 802.22, DVB T/H, ISDB-T, to name a few. We focus on the synchronization for the ISDB-T digital television system, currently adopted by several South American countries. The proposed approach uses the coarse synchronization to estimate the initial time reference and then, the fine synchronization keeps tracking the transmitter (TX) time reference. The innovation on the proposed approach regards to the closed loop control stabilization of the fine synchronization. It uses a smith predictor and a differential estimator, which estimates the difference between TX and RX clock frequencies. The proposed method allows the RX to track the TX time reference with high precision ([Formula: see text] sample fraction). Thus, the carriers phase rotation issue due to incorrect time reference is minimized, and it does not affect the proper RX IQ symbols demodulation process. The RX internal time reference is adjusted based on pilot symbols, called scattered pilots (SPs) in the context of the ISDB-T standard, which are inserted in the frequency domain at the inverse fast Fourier transform (IFFT) input in the TX. The averaged progressive phase rotation of the received SPs at the fast Fourier transform (FFT) output is used to compute the time misalignment. This misalignment is used to adjust the RX fine time synchronism. Furthermore, the proposed method has been implemented in an ISDB-T RX. The FPGA-based receiver has been evaluated over several multipath, Doppler and AWGN channel models.

scholarly journals Channel estimation of OFDM in C-band communication systems under different distribution conditions

2021 ◽  
Vol 23 (3) ◽  
pp. 1778
Author(s):  
Heba Abdul-Jaleel Al-Asady ◽  
Hassan Falah Fakhruldeen ◽  
Mustafa Qahtan Alsudani
Keyword(s):  
Fourier Transform ◽  
Channel Estimation ◽  
Fast Fourier Transform ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Ofdm System ◽  
High Data ◽  
High Efficient

<p>Orthogonal frequency division multiplexing (OFDM) is a transmission system that uses multiple orthogonal carriers that are sent out at the same time. OFDM is a technique for mobile and wireless communication that has high-efficient frequency utilization, high data-rate transmission, simple and efficient implementation using the fast Fourier transform (FFT) and the inverse fast Fourier transform (IFFT), and reduces inter symbol interference (ISI) by inserting cyclic prefix (CP). One of the most important approaches in an OFDM system is channel estimation. In this paper, the orthogonal frequency division multiplexing system with the Rayleigh channel module is analyzed for different areas. The proposed approach used large numbers of subcarriers to transmit the signals over 64-QAM modulation with pilot add channel estimation. The accuracy of the OFDM system is shown in the measuring of the relationships of peak power to the noise ratio and bit error rate.</p>

scholarly journals A Novel Noise Suppression Channel Estimation Method Based on Adaptive Weighted Averaging for OFDM Systems

Symmetry ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 997 ◽  
Author(s):  
Zhang ◽  
Zhou ◽  
Wang
Keyword(s):  
Fourier Transform ◽  
Channel Estimation ◽  
Fast Fourier Transform ◽  
Orthogonal Frequency Division Multiplexing ◽  
Noise Suppression ◽  
Estimation Method ◽  
Weighted Averaging ◽  
Doppler Spread ◽  
Estimation Methods ◽  
Ofdm Systems

Orthogonal frequency division multiplexing (OFDM) systems have inherent symmetric properties, such as coding and decoding, constellation mapping and demapping, inverse fast Fourier transform (IFFT) and fast Fourier transform (FFT) operations corresponding to multi-carrier modulation and demodulation, and channel estimation is a necessary module to resist channel fading in the OFDM system. However, the noise in the channel will significantly affect the accuracy of channel estimation, which further affects the recovery quality of the final received signals. Therefore, this paper proposes an efficient noise suppression channel estimation method for OFDM systems based on adaptive weighted averaging. The basic idea of the proposed method is averaging the last few channel coefficients obtained from coarse estimation to suppress the noise effect, while the average frame number is adaptively adjusted by combining Doppler spread and signal-to-noise ratio (SNR) information. Meanwhile, to better combat the negative effect brought by Doppler spread and inter-carrier interference (ICI), the proposed method introduces a weighting factor to correct the weighted value of each frame in the averaging process. Simulation results show that the proposed channel estimation method is effective and provides better performance compared with other conventional channel estimation methods.

scholarly journals High-resolution wide-band fast Fourier transform spectrometers

2012 ◽  
Vol 542 ◽  
pp. L3 ◽  
Author(s):  
B. Klein ◽  
S. Hochgürtel ◽  
I. Krämer ◽  
A. Bell ◽  
K. Meyer ◽  
...  
Keyword(s):  
Fourier Transform ◽  
High Resolution ◽  
Fast Fourier Transform ◽  
Wide Band

scholarly journals Enhancing Performance of Orthogonal Frequency Division Multiplexing (OFDM) Based On Fast Fourier Transform (FFT) In Wireless Communication System

2019 ◽  
Vol 8 (3) ◽  
pp. 2003-2008
Keyword(s):  
Fourier Transform ◽  
Wireless Communication ◽  
Fast Fourier Transform ◽  
Communication System ◽  
Orthogonal Frequency Division Multiplexing ◽  
Modulation Method ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Multicarrier Transmission ◽  
Wireless Communication System

Orthogonal Frequency Division Multiplexing (OFDM) is one of the multicarrier transmission techniques used in wireless communication system. It has many benefits such as robust in channel fading and has high spectral density. The main objective of OFDM implementation in wireless communication system is to achieve less or zero Bit Error Rate (BER). However, OFDM design complexity, requirement and selection of the suitable modulation method are among the current issues. Thus, this paper aims to investigate the performance of OFDM in wireless communication by developing two OFDM based system designs. The transmitter, channel and receiver are designed based on OFDM system principles. Forward Error Correction (FEC) method is applied to reduce the BER. Both OFDM designs produce less BER with zero BER for the second OFDM design. The investigation study shows that the performance of OFDM can be enhanced by applying Fast Fourier Transform (FFT) technique. Zero BER can be achieved if the suitable modulation scheme is applied in the system. The developed designs are not complex, suitable to be applied for IEEE 802.11 standard. The BER performance can be influenced by the types of channels, signal to noise ratio (SNR) and various modulation schemes. Thus, this study can be used as a guidance to implement the OFDM in the current or future wireless communication system.

scholarly journals Simulation of Memory-Based 1024-Point Fast Fourier Transform for Broadband Wireless Access Technology on FPGA

2017 ◽  
Vol 1 (02) ◽  
pp. 28-36 ◽  
Author(s):  
Dinda Pramanta ◽  
Denny Darlis ◽  
Iswahyudi Hidayat
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Power Efficiency ◽  
Orthogonal Frequency Division Multiplexing ◽  
Wireless Access ◽  
Computational Time ◽  
Broadband Wireless Access ◽  
Access Technology ◽  
Broadband Wireless ◽  
Flip Flop

The limited radio frequency spectrum that can be used for transmission leads to bandwidth and power efficiency being a key requirement in the development of wireless access technology from 3G to 5G today. Data communication technology also requires this as mentioned on high speed network standards such as DSL, WLAN and WMAN with its products ADSL, WiFi and Wimax. In the last few decades we have seen the evolution of the Orthogonal Frequency Division Multiplexing (OFDM) modulation technique used in the technologies mentioned earlier to this day. This technique is regarded as a standard technology for broadband wireless access technology. In hardware implementation, the most preferred by many researchers is the Field Programmable Gate Array chip, as it can be reconfigured. The OFDM technique can be easily implemented because it uses Fast Fourier Transform (FFT) algorithms that are coding and programming capable of reducing the computational time of Discrete Fourier Transform. This paper discusses the implementation of the memory-based 1024-point IFFT / FFT for BWA communications. The design is focused on synthesizing and implementing the system block FFT 1024-point radix-4 using Decimation in Frequency (DIF) method. Implementation for IFFT / FFT 1024-point resource usage slice number 1%, the number of slice flip-flop 1%, the number 4 LUT (Look Up Table) 1%, and the number of IOB 27%. of the FPGA are used.

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