Description: 本文首先概述了OFDM 的原理、特征和关键技术，介绍了系统需要的几种同步。然后就同步误差对系统性能的影响进行了简单的分析，表明定时偏差和采样频率偏差将会引入码间干扰，载波频率偏差导致载波间干扰的发生。因此，在OFDM系统接收机中定时的确定、载波频率偏差和采样频率偏差的纠正是信号恢复的关键。之后对OFDM系统同步的几种实现方法进行了介绍，分析了各同步方法的性能。-The paper first outlines the principles of OFDM, features and key technologies, the system needs to introduce several synchronization. Synchronization error and then the impact on system performance for a simple analysis, show that the timing deviation and the sampling frequency deviation will introduce inter-symbol interference, the carrier frequency deviation led to the occurrence of ICI. Therefore, in OFDM system receiver to determine the timing, carrier frequency offset and sampling frequency offset correction signal to restore the key. After the OFDM system to achieve synchronization of several methods of introduction, an analysis of the performance of the synchronization method. Platform: |
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Author:dajinyu |
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Description: In this simulink model , baseband binary detection is simulated .A rectangular pulse shaped signal is given as input to the detector.The received signal is matched filtered and down-sampled .The effects of symbol timing offset can be seen by varying the phase of down-sampling operation.The binary signal transmitted is recovered
at the detector output.-In this simulink model , baseband binary detection is simulated .A rectangular pulse shaped signal is given as input to the detector.The received signal is matched filtered and down-sampled .The effects of symbol timing offset can be seen by varying the phase of down-sampling operation.The binary signal transmitted is recovered
at the detector output. Platform: |
Size: 7168 |
Author:quail |
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Description: In this simulink model , baseband 8-ary PAM detection is simulated .A half-sine pulse shaped PAM signal is given as input to the detector.The received signal is matched filtered and down-sampled .The effects of symbol timing offset
can be seen by varying the phase of down-sampling
operation.The 8-ary PAM signal transmitted is recovered
at the detector output. Platform: |
Size: 8192 |
Author:quail |
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Description: In this simulink model , 16-QAM modulation and demodulation is simulated .A square root raised cosine pulse shaped signal is modulated and given as input to the demodulator.The received signal
is demodulated and given to the detector where it is matched filtered and down-sampled .The effects of symbol timing offset
can be seen by varying the phase of down-sampling
operation.The signal transmitted is recovered
at the detector output.-In this simulink model , 16-QAM modulation and demodulation is simulated .A square root raised cosine pulse shaped signal is modulated and given as input to the demodulator.The received signal
is demodulated and given to the detector where it is matched filtered and down-sampled .The effects of symbol timing offset
can be seen by varying the phase of down-sampling
operation.The signal transmitted is recovered
at the detector output. Platform: |
Size: 9216 |
Author:quail |
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Description: In this simulink model , QPSK modulation and demodulation is simulated .A square root raised cosine pulse shaped signal is modulated and given as input to the demodulator.The received signal
is demodulated and given to the detector where it is matched filtered and down-sampled .The effects of symbol timing offset can be seen by varying the phase of down-sampling operation.The signal transmitted is recovered at the detector output.-In this simulink model , QPSK modulation and demodulation is simulated .A square root raised cosine pulse shaped signal is modulated and given as input to the demodulator.The received signal
is demodulated and given to the detector where it is matched filtered and down-sampled .The effects of symbol timing offset can be seen by varying the phase of down-sampling operation.The signal transmitted is recovered at the detector output. Platform: |
Size: 8192 |
Author:quail |
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Description: OFDM通信系统调制解调 包括数字前端处理、卷积编码、峰均值抑制、符号定时、频偏检测、信道估计、相位补偿等-OFDM modulation and demodulation communication system including digital front-end processing, convolution coding, the mean peak inhibition, symbol timing, frequency offset detection, channel estimation, phase compensation Platform: |
Size: 119808 |
Author:宋巍 |
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Description: 为了减少无线信道中存在的多径和频偏对中国移动多媒体广播(CMMB)系统传输信号同步的影响，本文结合CMMB标准协议规定的具体帧结构，分析了符号同步对系统的影响，讨论了传统最大似然(ML)算法的优缺点，并基于文献中的无数据辅助算法，提出了一种适合该系统并且复杂度较低的粗符号定时同步算法。仿真结果表明，在AWGN及多径信道环境下，新算法可以有效克服传统算法相关峰不明显的缺陷，其估计性能更好-In order to reduce the influence for synchronization of signals in CMMB (China Mobile Multimedia Broadcasting) system, which caused by multi-path and frequency offset in wireless channel. This paper combined the specific frame structure of CMMB standard protocol, analyzed the impact of symbol synchronization, discussed advantages and disadvantages of the traditional ML (Maximum Likelihood) algorithm, and based on the non-data auxiliary algorithm in literature, proposed a coarse symbol timing synchronization algorithm, it is suitable for the system and its complexity is very low. Simulation results show that the new algorithmof signals in CMMB Platform: |
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Author:JFS |
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Description: 文章介绍了平坦衰落下的频偏和同步联合恢复技术，能够有效应对时变的信道，并且不需要训练序列，给出了详细的仿真和分析，供大家学习-Two open-loop algorithms are developed for esti-
mating jointly frequency offset and symbol timing of a linearly
modulated waveform transmitted through a frequency-fl at fading
channel. The methods exploit the received signal’s second-order
cyclostationarity and, with respect to existing solutions: 1) they
take into account the presence of time-selective fading effects 2)
they do not need training data 3) they do not rely on the Gaussian
assumption of the complex equivalent low-pass channel process
and 4) they are tolerant to additive stationary noise of any color
or distribution. Platform: |
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Author:caiyh |
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Description: A fully digital feedforward MSK demodulator with joint frequency offset and symbol timing estimation for burst mode mobile radio Platform: |
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Author:邓杰 |
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Description: 一种新的符号定时和载波频率同步算法,该算法将OFDM符号分成几部分。它使用相关性和积累在几个OFDM
符号获得估计函数。当部分的长度小于ISI自由地区,该算法可以识别它。然后估计的最优符号定时和载波频率偏移可以获得。计算机仿真结果表明,该算法不仅可以跟踪时变信道变化但也有较小的MSE比ML估计算法。-A new symbol timing and carrier frequency synchronization algorithm is presented and the algorithm divides the OFDM symbol into several parts. It uses correlation and accumulation in several OFDM
symbols to acquire estimation function. When the length of part is smaller than that of ISI free region , the algorithm can distinguish it. Then the estimation of optimal symbol timing and carrier frequency offset can be acquired .The computer simulation results show that the proposed algorithm not only can track time varying channel change but also has smaller MSE than that of ML
estimation algorithm. Platform: |
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Author:wujueying |
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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: |
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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: OFDM系统中符号定时偏差的估计仿真，基于cp-The estimate of the OFDM symbol timing offset in the system simulation based on cp Platform: |
Size: 2048 |
Author:易需 |
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Description: 基于CP的最大似然估计仿真图，两幅图，分别是符号定时偏差，以及频偏，从图中可以看出在符号定时估计最大处，相应的频偏估计值也是最接近的-CP-based maximum likelihood estimate simulation map, two maps, are a symbol timing offset, and frequency offset, it can be seen the figure in the symbol timing estimation is maximum, the corresponding value is also the closest frequency estimation Platform: |
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Author:小粉 |
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Description: 接收端采用的算法和程序流程与发送端发送的OFDM符号的帧结构有关系。具体的帧结构，以及定时估计，频偏估计，剩余误差跟踪的算法可参考算法说明文档。这里对程序的流程进行说明。
首先根据短训练字的特性进行相关运算，进行信号到达检测，当检测到相关值大于门限一定次数后，认为有信号到达。然后根据长训练字的特性，进行相关运算，进行OFDM符号FFT窗口起始位置的估计。估计出FFT窗口的位置后，先在时域进行小频偏的估计，将两个长训练字进行小频偏补偿后，进行FFT运算，根据FFT运算的结果进行整数倍频偏的估计。这些参数估计完成后，就可以进行数据解调了。先对数据部分进行完整的频偏补偿，然后根据估计的FFT窗口位置进行FFT运算得到频域的数据，进行解调。然后在对应于导频的子载波位置上提取出导频信息，根据导频信息估计出剩余定时误差以及剩余的信道响应误差，将误差量送入环路进行跟踪。当收到所有数据后，重新回到信号到达检测状态，进行下一次信号到达的检测和信号接收。
-The receiving end uses the algorithm and the program flow and the frame structure of the OFDM symbol transmitted by the sending end. Specific frame structure, and timing estimation, frequency offset estimation, residual error tracking algorithm can refer to the documentation. Here to illustrate the process of the program.
First, according to the characteristics of the short training word correlation operation, the signal reaches the detection, when the correlation value is greater than the threshold of a certain number of times, that there is a signal to reach. Then, according to the characteristics of the long training word, the correlation operation is carried out, and the initial position of the OFDM symbol FFT is estimated. The estimated position of the FFT window, first in the time domain for small frequency offset estimation, two long training word for small frequency offset compensation, the FFT operation. According to the result of FFT for integer frequency bias estimation. Af Platform: |
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Author:shinfer |
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Description: ：LTE(Long Term Evolution，长期演进)系统中的小区初始搜索过程通过分别检测主同步信号(Primary Synchronization Signal，PSS)和辅同步信号(Secondary Synchronization Signal，SSS)来完成，搜
索结果包括小区组ID、符号定时、频偏估计、组内小区ID以及帧定时[1]。然而，若接收信号 1IDN 2IDN
中存在整数倍频偏，则由于时域的相位旋转，主同步信号将很难用传统的相关算法检测到。提出一种主同步信号与整数倍频偏联合检测的方法，即使存在整数倍频偏，也能得到正确的符号定时。辅同步信号采用的是非相干的差分相关检测[2]，仿真表明，与传统的匹配滤波算法相比，可以有效的对抗信道时延扩展和载波频偏，适用于高速场景下时分双工(Time Division Duplex，TDD)LTE系统的同步。-In LTE systems, the initial cell search process is completed by detecting the primary synchroniza-tion signal and the secondary synchronization signal. The searching results include cell ID group, symbol timing, frequency offset estimation, intra group cell ID and frame timing[1]. However, if integer frequency offset presents in the received signal, due to time-domain phase rotation, the primary synchronization signal will be difficult to detected using the conventional correlation algorithm. A new joint detection method for integer frequency offset and primary synchronization signal is proposed, which can get the correct symbol timing even if the presence of integer frequency offset. Secondary synchronization signal is processed using the differential non-coherent correlation detection method[2]. Simulations show that compared with the tradi-tional matched filtering algorithms, it can effectively combat the channel delay spread and carrier frequency offset and especially suitable for Platform: |
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Author:imc_lte |
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Description: ofdm符号定时与频偏估计的Matlab实现程序(Matlab implementation program for OFDM symbol timing and frequency offset estimation) Platform: |
Size: 2048 |
Author:老朋友1214
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Search - symbol timing offset