英语翻译MC-CDMA inherits the interference rejection capability o

英语翻译
MC-CDMA inherits the interference rejection capability of CDMA,and the potential of mitigating multipath propagation effects of orthogonal frequency division multiplexing
(OFDM).MC-CDMA with its frequency diversity is an attractive modulation scheme for multi-user high data rate wireless communication system.However on OFDM and MCCDMA sub-channel decomposition cannot be achieved without adding guard band or cyclic prefix,where a copy of the end part of the data symbol block is transmitted.Due to the relationship between circular and linear convolutions in discrete Fourier transform (DFT),
the residual inter symbol interference (ISI) is eliminated by dropping the guard interval part in the receiver.This method needs transmitting extra guard interval signals that introduces
overhead and thus leads to spectral inefficiency and performance degradation.An efficient scheme which not only counters the degrading effects of ISI but also conserves the bandwidth is the application of discrete wavelet packet transform (DWPT) based MCCDMA.In this paper we replace Fourier based complex exponential carriers of MC-CDMA with an orthonormal wavelets packets,such as daubechies,haar,biorthogonal,discrete
meyer and coiflets to compare the performance of MC-CDMA based discrete fourier transform (DFT) and MC-CDMA based discrete wavelet packet transform(DWPT).
Wireless communications using MC-CDMA offer tremendous opportunity to support high data rate and combat the inter-symbol interference (ISI) due to the multipath propagation effects,inherently present in the wireless channel.The use of single carrier modulation scheme may prove to be unfruitful,since the channel induced inter-symbol interference,can easily distort the data carried by a single carrier.Multi-carrier
modulation (MCM) offers the advantage of spreading out a frequency selective fading over many symbols,which effectively randomizes burst errors caused by fading or impulse noise,so that instead of several adjacent symbols being completely destroyed; many symbols are only slightly distorted.However,the quest for better solution in terms of modulation techniques that could accommodate high data rates,continued and an idea of
combining MCM with code division multiple access (CDMA) was born in 1993 [1].It combines the advantages of CDMA such as interference rejection,frequency reuse etc.,with the advantage of OFDM such as robustness against multipath and impulse noise [2].However,the problem of frequency offset is considered one
of the main drawback of MC-CDMA systems [3],[4],resulting from Doppler’s shift which introduced signal distortion and power loss.In recent years discrete Fourier transform based MC-CDMA is being replaced by a wavelet packet waveforms which have the property of localization in both time and frequency domain [5],[6],[7],[8].

MC-CDMA继承CDMA的干涉拒绝能力和缓和正交频率分割多元化的多重通道的传播作用潜力
(OFDM).MC-CDMA以它的频率分集是多用户高数据速率无线通信系统的一份有吸引力的模块化计划.然而在OFDM和MCCDMA子通道分解不可能达到不增加防护频带或循环前缀,数据标志块的末端零件的拷贝被传送.由于圆和线性卷积之间的关系在分离傅立叶变换(DFT),投下在接收器的卫兵间隔时间零件消灭the残余的相互标志干涉(ISI).介绍的这个方法需要传送额外卫兵间隔时间信号
overhead和因而导致鬼无效用和性能退化.不仅抵抗ISI的贬低的作用的一份高效率的计划,而且保存带宽是分离小波小包的应用变换(DWPT)基于MCCDMA.在本文我们用替换傅立叶MC-CDMA基底杂岩指数载体规格化正交的小波小包,例如daubechies,haar,biorthogonal,分离 比较MC-CDMA基于分离傅立叶变换(DFT)和MC-CDMA基于分离小波小包表现的meyer和coiflets变换(DWPT).使用MC-CDMA的Wireless通信提供巨大机会支持高数据速率和与码元窜扰(ISI)交战由于多重通道的传播作用,本质上地礼物在无线渠道.使用唯一载体模块化计划也许证明无效的,因为渠道导致了码元窜扰,可能容易地变形一个唯一载体运载的数据.多载体
modulation (MCM)提供延长一频率有选择性退色的好处在许多标志,有效地随机化退色或脉冲噪声造成的猝发错误,因此而不是完全地被毁坏的几个毗邻标志; 许多标志少许被变形.然而,对更好的解答的寻求根据可能容纳高数据速率的模块化技术,被继续和想法 与代码区分多存取(CDMA)的combining MCM在1993年出生[1].它与OFDM的好处结合CDMA的好处例如干涉拒绝,频率再用等,例如强壮反对多重通道和脉冲噪声[2].然而,频率偏移的问题被考虑一个
of主要缺点MC-CDMA系统[3],[4],起因于介绍信号畸变和功率损失的Doppler’s转移.近年来分离傅立叶变换基于MC-CDMA被有地方化物产在时间和频域的小波小包信号波形替换[5],[6],[7],[8].