正子

Carrier Frequency offsets in OFDMA system will introduce InterCarrier Interference and consequently degrade the system performance.

摘要由于载波频偏会给正交频分多址接入OFDMA系统带来子载波之间干扰，从而造成多用户之间的干扰，导致系统性能下降。

However, for mobile applications, channel variations within an OFDM block period destroy the orthogonality between subcarriers; the effect, known as Intercarrier Interference, will degrade the system performance.

然而在行动通讯的应用上，时变通道破坏了子载波间的正交性，造成载波间的互相干扰因而降低系统效能。

With high carrier frequency in future communication systems and long OFDM symbol caused by and large subcarrier number, high mobile velocity that will result in fast-fading channels, will make the OFDM system suffered by the intercarrier interference.

随着未来系统的高移动速度，高载频和大子载波数所导致的长OFDM符号都将使系统的性能正越来越深地受到快速时变多径信道所带来子载波间干扰的影响。

However, OFDM systems can be extremely sensitive to synchronization errors. Minor carrier frequency offset and symbol time offset can cause intersymbol and intercarrier interference and degrade system performance very seriously.

然而，正交分频多工对於对同步错误极为敏感，些许的载波频率偏移与符元时序偏移就能造成符际干扰及子载波干扰，导致系统效能变差。

Doppler frequency offsets in rapid mobile environments result in both the fast fading of radio channels and intercarrier interference in Orthogonal Frequency Division Multiplexing systems. In order to combat the impact of ICI on OFDM systems in fast fading channels, an ICI mitigation technique is proposed in this paper.

针对高速移动环境下多普勒频偏造成移动信道的快衰落和正交频分复用系统中子载波间干扰问题，提出了一种适合快衰落环境的OFDM系统子载波间干扰抑制算法。

Time variations corrupt the orthogonality of the OFDM subcar-rier waveforms so that intercarrier interference occurs.

OFDM系统对时间选择特性信道非常敏感，Doppler频移的出现会造成OFDM系统子载波不再正交，对系统引入载波间干扰。

Inherent inter-symbol and inter-carrier interference elimination ability of orthogonal frequency division multiplexing system attribute to its cyclic prefix. But the case of multipath fading channels whose the channel impulse response length exceeds the duration of cyclic prefix causes intersymbol interference and intercarrier interference, which may degrade system performance severely.

正交频分复用系统中的循环前缀具有一定的抗码间干扰和子载波间干扰的能力，但是当多径衰落信道的最大信道脉冲响应长度超过了循环前缀长度时，OFDM系统的性能将会严重下降。

Due to the fact that the intercarrier spacing in OFDM is relatively small, OFDM transceivers are somewhat more sensitive to phase noise compared to single carrier transceivers. Thus this problem must be carefully considered in designing an OFDMbased system since an accurate prediction of the tolerable phase noise can allow designer to relax system specifications. According to spectrum theorem, two components of phase noise were analyzed: common phase error and intercarrier interference. On the basis of the analysis, the performance of OFDM was given for the case where phase noise has been added to the signal, and an optimal design criterion for OFDM parameters was proposed that allows to improve the phase noise error correcting capabilities in OFDM receiver.

由于采用子载波间相互正交的结构，OFDM系统对于由本地振荡器不稳定性所导致的相位噪声影响非常敏感，针对公共相位误差CPE和载波间干扰ICI两种影响表现形式不同的干扰项，从功率谱密度函数这一独特角度分析了相位噪声对OFDM系统性能的影响，提出了旨在提高接收机抵抗相位噪声能力的OFDM系统关键参数优化与设计准则，可在对所设计OFDM系统性能加以提高的同时，有效降低对接收机前端模拟振荡器件和相位噪声抑制单元的性能指标要求，从而降低接收机硬件实现成本。

These matrices are the inversive constant ones and have the size as the same as the length of the signal.

利用基于推选体制的小波变换实现算法，构造出了与具有紧支集的双正交小波滤波器对应的小波变换和逆小波变换的算子矩阵，这些矩阵是大小与信号长度相等的可逆常数矩阵。

By orthogonal experiment,extraction technique of volatile oils from the fruits of Litsea mollis Hemsl.

采用正交实验法对超临界CO2萃取毛叶木姜子果实挥发油的条件进行了研究。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。