基于频分的MC-CDMA多用户系统

The Multi - user MC - CDMA System Based on Frequency Division

对多载波码分多址系统的多用户接收进行了研究,提出了基于频分的多载波码分多址(FD—MC—CDMA)系统,它是在MC—CDMA基础上结合FDMA的思想,发射端为每个用户分配一个特定的子载波集进行数据传输,减少相同子栽波上所叠加用户的数目;接收端使用最大似然检测器,利用所有接收信号进行多用户联合检测。该系统与传统的MC-CDMA系统相比有保证频率分集增益的同时降低多址干扰、有效利用多用户信息的优点。经过在Matlab平台上的仿真,结果表明,在频率选择性衰落信道和相同接入用户数的情况下,该系统与传统的MC—CDMA系统相比拥有更低的误码率,并且误码率随着用户数的增加呈阶梯状的缓慢递增。

A research on the multi - user reception in the MC - CDMA system is done, and a scheme of MC - CDMA system based on the frequency division is put forward. The mode is based on the MC - CDMA and the idea of FDMA. A specific sub - carrier is distributed for each user＇s data transmission in the transmitter, reducing the number of users occupying the same sub - carriers. The Maximum Likelihood Detector is used in the receiver for joint detection using all received signals. This scheme has the advantages over the traditional MC - CDMA system that it can obtain the frequency diversity gain and depress the effect of the MAI, and make full use of the multi - users＇ signals. The simulation on the MATLAB shows that this scheme has a lower BER in the circumstance of frequency selective fading channels and the same number of users, and the BER will increase in a staircase shape as the number of users increases.