κ−μ阴影衰落信道下非数据辅助的误差矢量幅度性能分析

摘要

κ?μ 阴影衰落信道下系统性能预测是无线通信中一个具有挑战性的问题,严重影响着传输机制设计.针对此问题,提出一种采用非数据辅助的误差矢量幅度(NDA-EVM,nondata-aided error vector magnitude)对κ?μ 阴影衰落信道进行性能分析的理论方法.选取NDA-EVM作为反映信道变化的评估参量,采用最大似然准则推导阴影衰落信道下不同调制阶数NDA-EVM统一的计算模型,并以衰落因子为中间变量,建立NDA-EVM与κ?μ 分布的联系,据此推导NDA-EVM 在κ?μ 阴影衰落信道的理论下限,并化简给出几种典型信道的性能界限.对所得结论进行理论分析和数值仿真模拟,结果表明:相较传统的DA-SNR(data-aided signal to noise ratio)和DA-EVM(data- aided error vector magnitude),NDA-EVM对κ?μ 阴影衰落信道的评估具有最小均方根误差;推导的下限与理论值有很高的吻合度,特别是在低SNR时为紧下界;下限与κ?μ 阴影衰落信道参数均呈负相关特性,对信道变化非常敏感.%The performance prediction of wireless system over κ?μ shadowed fading channels was a challenging problem of wireless communications, which affects transmission scheme design seriously. To solve this problem, a novel method of quantifying the κ?μ shadowed fading channels performance based on nondata-aided error vector magnitude(NDA-EVM) was proposed.NDA-EVM was considered as a new metric to evaluate the change of the channels.The unified model to calculate different modulation order of NDA-EVM was analytically derived by maximum likelihood criterion.Moreover,the relationship between the κ?μ distribution and the NDA-EVM was built by using the attenuation factor of the channel as intermediate variable.Thereafter,the lower bounds of the NDA-EVM over the κ?μ shadowed fading channels were formulated,which was also simplified for various typical channels. The theoretical analysis was taken, moreover, numerical results were also con-ducted to verify the effectiveness of the derived formulation.It shows that NDA-EVM estimation has the lest root mean square error than data-aided signal to noise ratio (DA-SNR) estimation and error vector magnitude (DA-EVM) estimation over the κ?μ shadowed fading channels.The derived lower bounds closely match the theoretical values,especially at low SNR.In ad-dition,the lower bounds are negatively related to all of the parameters of the κ?μ shadowed fading channels,which make it sensitive to the change of the fading channels.