Description: This project aim was to build wireless software modem for data communication
between two computers using an acoustic interface in the voice frequency range (20Hz–
20,000Hz). The transmitting antenna is a speaker (frequency response of: 90Hz –
20,000Hz) and the receiving antenna is a microphone (frequency response of: 100Hz –
16,000Hz). The test files used as information files were text files.
This goal was attained both in an incoherent scheme and in a coherent scheme.
Build under Matlab code, our modem uses OFDM (orthogonal frequency division
multiplexing) modulation, synchronization by LMS sequence, channel estimation (no
equalizer) via pilot tones. The symbols are either PSK or ASK for a constellation size of
2 or 4. To optimize the probability of error, these symbols were mapped using Gray
mapping.
Report Platform: |
Size: 559541 |
Author:buyop |
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Description: OFDM同步算法分析比较，用于个人学习使用 -Analysis and comparison of OFDM synchronization algorithm, used for personal learning Platform: |
Size: 3072 |
Author:祝捷 |
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Description: Part II presents the fundamental concepts andMATLAB programs for simulation ofOFDM
transmission techniques including OFDM basics, synchronization, channel estimation,
peak-to-average power ratio reduction, and intercell interference mitigation Platform: |
Size: 6810624 |
Author:Estifanos Yohannes |
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Description: A major challenge to MIMO-OFDM systems is how to obtain the channel state in-
formation accurately and promptly for coherent detection of information symbols and
channel synchronization.,A major challenge to MIMO-OFDM systems is how to obtain the channel state in-
formation accurately and promptly for coherent detection of information symbols and
channel synchronization. Platform: |
Size: 581632 |
Author:Nirupa |
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Description: A major challenge to MIMO-OFDM systems is how to obtain the channel state in-
formation accurately and promptly for coherent detection of information symbols and
channel synchronization.,A major challenge to MIMO-OFDM systems is how to obtain the channel state in-
formation accurately and promptly for coherent detection of information symbols and
channel synchronization. Platform: |
Size: 1074176 |
Author:Nirupa |
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Description: parie1: ICI Study generated by a synchronization error frequency in OFDM
partie2:Study of an Algorithm for Time Synchronization and Frequency in OFDM -parie1: ICI Study generated by a synchronization error frequency in OFDM
partie2:Study of an Algorithm for Time Synchronization and Frequency in OFDM Platform: |
Size: 102400 |
Author:takwa |
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Description: 中国数字地面电视标志的同步帧头的420点FFT算法。用于OFDM的调制和解调。因为是非基2，基4类的算法，所以还是有很大的参考性。-Chinese digital terrestrial television synchronization header logo 420-point FFT algorithm. For OFDM modulation and demodulation. Because the non-group 2, group 4 class algorithm, so it is still a great informative. Platform: |
Size: 173056 |
Author:林竞力 |
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Description: Three Timing Synchronization Methods Based on Two Same Preambles for OFDM Systems
The purpose of this paper is to propose two fast timing synchronization methods of OFDM System which has two preamble symbols, the two preamble symbols are used for SNR estimation for OFDM systems. The synchronization techniques are examined in Multipath fading environments for comparison. The results of the performance
comparison are presented in terms of mean obtained by simulations. Platform: |
Size: 268288 |
Author:Mohamed |
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Description: A Novel Time and Frequency Synchronization Scheme for OFDM Systems
A new training symbol is designed and a novel
time and frequency synchronization scheme for orthogonal frequency division multiplexing systems is proposed. The time synchronization is accomplished by using the symmetric conjugate of the training symbol in time domain and the frequency synchronization is finished by utilizing the good
autocorrelation of the training symbol in frequency domain.
The simulation results show that compared with conventional schemes, the proposed scheme gives a more accurate estimate of symbol timing and carrier frequency offset and provides a
wider acquisition range for the carrier frequency offset.1 Platform: |
Size: 321536 |
Author:Mohamed |
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Description: Time and Frequency Synchronization Techniques for
OFDM Systems operating in Gaussian and Fading
Channels: A Tutorial
The aim of this paper is to survey and compare
previous methods for Data-aided timing and frequency
synchronization of OFDM System. In the sequel, we propose a fast
and accurate FFT-based frequency offset estimation. The
synchronization techniques are examined in Gaussian andMultipath fading environments for comparison. The results of the
performance comparison are presented in terms of mean andmean-square error (MSE) obtained by simulations. The timing
offset estimator with best performance is chosen for system timingsynchronization. The FFT-based frequency offset estimation
method has significantly smaller MSE than others can beperformed using the same timing training symbol. Therefore,there is only one training symbol needed as preamble in whole
synchronization process.
Platform: |
Size: 340992 |
Author:Mohamed |
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Description: Frequency Synchronization in OFDM System
An accurate frequency synchronization method using the zadoff-chu (ZC) constant envelop preamble is analyzed, and a new preamble weighted by pseudo-noise sequence is used for orthogonal frequency division multiplexing (OFDM) systems. Using this method, frequency offset estimator range is greatly enlarged with no loss in accuracy. The range of the frequency estimation is ±30 of subcarrier spacing using ZC sequence as preamble. Simulations in the MATLAB for an AWGN channel show that the proposed method achieves superior performance to existing techniques in terms of frequency accuracy and range. Platform: |
Size: 349184 |
Author:Mohamed |
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Description: ofdm 传输与接受的各项例子
-OFDM Receiver
1. Initalize the USRP setting the RX parameters and moving the LO outside the transmission band.
2. Generate random data bits (PN Sequence) (125 bits)
3. Use the Van De Beek algorithm to detect the cyclic prefix locatoins for synchronization and estimate frequency offset
4. Remove the cyclic prefix
5. Remove the frequency offset the incoming signal
6. Compute the FFT convertin the time domain OFDM symbol to the frequency domain
7. Separate data bits, reference bits, and remove zero padding
8.Compute equalization coefficients using a linear fit for both I and Q based on reference symbols
9. Apply the equalization to the data symbols
10. Convert data symbol mapping back to data bits Platform: |
Size: 460800 |
Author:kai |
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Description: 正交频分复用(OFDM)技术是一种可以有效对抗符号间干扰(ISI)的高速数据传输技术。OFDM是一种特殊的多载波调制方式，它的基本思想是将高速传输的数据流通过串/并转换，变成在若干个正交的窄带子信道上并行传输的低速数据流。OFDM接收机有三个关键技术：信道估计技术，降低峰均比(PAPR)技术和同步技术。OFDM技术能有效的对抗多径衰落等，有着诸多的优点，但是OFDM有一个发展瓶颈，即OFDM信号的峰均功率比很大，很容易导致OFDM信号的交调失真和系统性能的下降。因而如何降低OFDM信号的峰均功率比一直是OFDM技术的一个研究热点问题。论文针对上述问题，重点研究了降低OFDM信号的峰均功率比的SLM与PTS算法，并利用Matlab对算法进行了仿真研究，并对仿真结果进行了分析。-Orthogonal frequency division multiplexing (OFDM) is a high-speed data transmission technology that can effectively combat inter-symbol interference (ISI). OFDM is a special multi-carrier modulation method, its basic idea is to high-speed transmission of data stream through the serial/parallel conversion, in a number of orthogonal narrowband sub-channel parallel transmission of low-speed data stream. OFDM receivers have three key technologies: channel estimation techniques, reduced peak-to-average ratio (PAPR) techniques and synchronization techniques. OFDM technology can effectively combat multipath fading, etc., there are many advantages, but OFDM has a bottleneck in development, that is, OFDM signal peak power ratio is large, it is easy to lead to OFDM signal intermodulation distortion and system performance degradation. Therefore, how to reduce the peak-to-average power ratio of OFDM signal has been a hot topic in OFDM technology. In this paper, the SLM and PTS algorithms for reduc Platform: |
Size: 142336 |
Author:num113 |
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Description: 6. 在三条径的瑞利信道中，对于OFDM：
(1) 请设计一种具体的导引辅助的信道估计方法，用Simulink进行仿真。画出比特信噪比与信道估计均方误差的关系曲线和比特信噪比与误码率的关系曲线。
(2) 设频率已同步，请设计OFDM一种具体的采用循环前缀进行时间同步方法，用Simulink进行仿真，画出比特信噪比与捕获概率的关系曲线。
(3) 设时间已同步，请设计OFDM一种具体的采用循环前缀进行频率同步方法，用Simulink进行仿真，画出比特信噪比与频率同步误差的关系曲线。(6. In the three-path Rayleigh channel, for OFDM:
(1) please design a specific navigation-assisted channel estimation method and use Simulink for simulation.The relation curves of bit signal-noise ratio and channel estimation mean square error and the relation curves of bit signal-noise ratio and bit error rate are drawn.
(2) if the frequency has been synchronized, please design a specific method of time synchronization using cyclic prefix in OFDM. Simulink is used for simulation to draw the relationship curve between bit-snr and acquisition probability.
(3) if time has been synchronized, please design a specific method of frequency synchronization using cyclic prefix in OFDM. Simulink is used for simulation to draw the relationship curve between bit signal-to-noise ratio and frequency synchronization error.) Platform: |
Size: 318464 |
Author:kmdcdy |
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Description: One of the major challenges which prevents the coordinated multipoint (CoMP) communications concept from being widely deployed in new cellular systems is timing synchronization. In order to achieve the gains promised by CoMP systems, the user equipments’ (UEs) signals in uplink (UL) or the base stations’ (BSs) signals in downlink (DL) should be synchronized such that the time difference of arrivals (TDOAs) do not exceed the cyclic prefix (CP) length of the transmitted signals; Otherwise the system suffers from unavoidable integer time offsets. These offsets lead to asynchronous interference in terms of inter-carrier, inter-block and inter-symbol interference (ISI). This limits the percentage of area within a cell which can be covered by cooperation and imposes an upper bound on this area. In this paper, we investigate this problem in the UL and by using geometrical and semi-analytical approaches, we define this upper bound. Also, by characterizing an accurate mathematical model for the asynchronous interference in Rayleigh fading channels, we were be able to employ a standard MMSE-based receiver that mitigates this interference. Furthermore, a typical joint channel and delay estimation block is incorporated into the receiver to examine its performance with estimation errors. Platform: |
Size: 1869319 |
Author:ahamza |
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Search - Synchronization for OFDM