A carrier recovery method of the power spectrum center difference adapting to the mobile channel of the MC CDMA system with serious Doppler shift using double pilots is presented. In the transmitter, two pilots o...A carrier recovery method of the power spectrum center difference adapting to the mobile channel of the MC CDMA system with serious Doppler shift using double pilots is presented. In the transmitter, two pilots of equal frequency distance to the carrier with one putting on the left position and the other on the right position of the carrier frequency are used. Even if a continuous sine wave is transmitted, the power spectrum is expanded to a Doppler band in the receiver owing to the multi path transmission and the Doppler shift. The pilot spectrum is made to pass through two narrow band filters which are transformed to the base band with local carrier wave in the receiver. The frequency difference between the local carrier and the transmitter carrier is obtained when the difference of the gravity centers of the two pilot spectra is computed.展开更多
提出了一种M IM O(m u ltip le inpu tm u ltip le ou tpu t)-OFDM(orthogona l frequency d iv is ion m u ltip lex-ing)系统前导结构以及基于相关的帧/符号同步、载波频率同步方案,详细介绍了同步算法,并给出高斯白噪声信道和频率选...提出了一种M IM O(m u ltip le inpu tm u ltip le ou tpu t)-OFDM(orthogona l frequency d iv is ion m u ltip lex-ing)系统前导结构以及基于相关的帧/符号同步、载波频率同步方案,详细介绍了同步算法,并给出高斯白噪声信道和频率选择性衰落信道中的仿真结果.结果表明,这种同步方案算法复杂度低,具有较高的精度和较大的实用价值.展开更多
This paper analyzed the structure of Orthogonal Frequency Division Multiplex （OFDM） system and presented a new Carrier Frequency Offset （CFO） tracking algorithm, which depends on comparability between the decision...This paper analyzed the structure of Orthogonal Frequency Division Multiplex （OFDM） system and presented a new Carrier Frequency Offset （CFO） tracking algorithm, which depends on comparability between the decision data and the original data to correct carrier frequency offset. Therefore it is robust during the normal communization process since the Bit Error Rate （BER） of the decision data is low. We can utilize pilot data in time domain for channel estimation to track CFO without reducing system efficient and to enhance the tracking scope largely. Simulation results denote the presented algorithm can track the frequency offset and control it under ± 1% using only 1 frame if the original frequency offset is within ±8% .展开更多
针对载波频偏引起的子载波间干扰问题,提出一种基于独立分量分析的OFDM(orthogonal frequency division multiplexing)载波频率同步算法。本算法直接实现载波频率同步,可以避免基于导频机制的频偏估计和由频偏估计误差带来的频谱效率降...针对载波频偏引起的子载波间干扰问题,提出一种基于独立分量分析的OFDM(orthogonal frequency division multiplexing)载波频率同步算法。本算法直接实现载波频率同步,可以避免基于导频机制的频偏估计和由频偏估计误差带来的频谱效率降低与性能损失。首先建立含频偏OFDM独立分量分析模型,然后从最大似然原则得到分离的代价函数,结合自然梯度优化得到OFDM源信号实现载波频率同步。理论分析表明,提出的算法不仅具有基于最大似然的频偏补偿性能而且提高了系统的输出信噪比。最后,仿真分析证明了算法的有效性。展开更多
通过研究最大相似性(Maximum Likelihood,ML)算法,并将其应用到正交频分复用(OFDM,Orthogonal Frequency Division Multiplexing)系统中,对其性能进行分析。OFDM系统较其他无线通信系统有明显的优势,但是也存在着对同步误差敏感的缺点,...通过研究最大相似性(Maximum Likelihood,ML)算法,并将其应用到正交频分复用(OFDM,Orthogonal Frequency Division Multiplexing)系统中,对其性能进行分析。OFDM系统较其他无线通信系统有明显的优势,但是也存在着对同步误差敏感的缺点,而ML算法可以解决OFDM系统的这一缺点。ML算法是利用OFDM码元中循环前缀所携带的冗余信息,并对其进行最大似然估计算法进行计算,尽而来完成码元定时同步和载波频率同步的一种算法。ML算法相对于其他同步算法,可以一步完成初始捕获和同步跟踪,因此被广泛应用于OFDM系统中。展开更多
基金Theworkissupportedbythenationalnaturalsciencefund! (No .6 9872 0 0 8)
文摘A carrier recovery method of the power spectrum center difference adapting to the mobile channel of the MC CDMA system with serious Doppler shift using double pilots is presented. In the transmitter, two pilots of equal frequency distance to the carrier with one putting on the left position and the other on the right position of the carrier frequency are used. Even if a continuous sine wave is transmitted, the power spectrum is expanded to a Doppler band in the receiver owing to the multi path transmission and the Doppler shift. The pilot spectrum is made to pass through two narrow band filters which are transformed to the base band with local carrier wave in the receiver. The frequency difference between the local carrier and the transmitter carrier is obtained when the difference of the gravity centers of the two pilot spectra is computed.
文摘提出了一种M IM O(m u ltip le inpu tm u ltip le ou tpu t)-OFDM(orthogona l frequency d iv is ion m u ltip lex-ing)系统前导结构以及基于相关的帧/符号同步、载波频率同步方案,详细介绍了同步算法,并给出高斯白噪声信道和频率选择性衰落信道中的仿真结果.结果表明,这种同步方案算法复杂度低,具有较高的精度和较大的实用价值.
基金This work is supported by National Natural Science Fundation of China(60372099) , and National "863" High Technology Projects of China(2001AA123016) .
文摘This paper analyzed the structure of Orthogonal Frequency Division Multiplex （OFDM） system and presented a new Carrier Frequency Offset （CFO） tracking algorithm, which depends on comparability between the decision data and the original data to correct carrier frequency offset. Therefore it is robust during the normal communization process since the Bit Error Rate （BER） of the decision data is low. We can utilize pilot data in time domain for channel estimation to track CFO without reducing system efficient and to enhance the tracking scope largely. Simulation results denote the presented algorithm can track the frequency offset and control it under ± 1% using only 1 frame if the original frequency offset is within ±8% .
文摘针对载波频偏引起的子载波间干扰问题,提出一种基于独立分量分析的OFDM(orthogonal frequency division multiplexing)载波频率同步算法。本算法直接实现载波频率同步,可以避免基于导频机制的频偏估计和由频偏估计误差带来的频谱效率降低与性能损失。首先建立含频偏OFDM独立分量分析模型,然后从最大似然原则得到分离的代价函数,结合自然梯度优化得到OFDM源信号实现载波频率同步。理论分析表明,提出的算法不仅具有基于最大似然的频偏补偿性能而且提高了系统的输出信噪比。最后,仿真分析证明了算法的有效性。
文摘通过研究最大相似性(Maximum Likelihood,ML)算法,并将其应用到正交频分复用(OFDM,Orthogonal Frequency Division Multiplexing)系统中,对其性能进行分析。OFDM系统较其他无线通信系统有明显的优势,但是也存在着对同步误差敏感的缺点,而ML算法可以解决OFDM系统的这一缺点。ML算法是利用OFDM码元中循环前缀所携带的冗余信息,并对其进行最大似然估计算法进行计算,尽而来完成码元定时同步和载波频率同步的一种算法。ML算法相对于其他同步算法,可以一步完成初始捕获和同步跟踪,因此被广泛应用于OFDM系统中。
