针对载波频率偏差导致变换域通信系统的接收信号幅度下降并产生载波间干扰的问题,通过建立系统模型,推导出了载波频偏存在情况下系统误码率的解析式,在此基础上,分析了子载波个数、频谱使用率以及载波频偏与系统输出信噪比的关系,以信噪比损失为度量,定量地给出了载波频偏对系统性能的影响,最后进行了仿真验证,仿真结果与数值分析高度吻合。仿真结果表明:频偏显著影响系统性能,且归一化载波频偏大于0.6时与误码率之间会出现地板效应;为避免系统性能恶化,归一化频偏应控制在0.05的范围内。
Considering the situation that the received signals magnitude is decreased and inter-carrier interference (ICI) is induced by the carrier frequency offsets (CFO), through establlslalng matnemancat mouel, the analytical expression for the Bit Error Rate (BER), which is derived from Transform Domain commu- nication system (TDCS), is obtained. Furthermore, the relationships between the BER and the correlated parameters are studied, as well as, the Signal Noise Ratio (SNR) loss. Finally, the analysis conclusions are verified by the simulation, the simulation result agrees well with the analysis conclusion. The quantitative analysis of the system performance caused by the frequency error of carrier is given. These researches illustrate that the frequency offset affect the BER performance seriously and there is error floor on the BER when the normalized frequency offset is more than 0.6. To keep the system work around, the normalized frequency offset has to be less than O. 05.