解调环路非理想特性对预失真系统的影响

借助半实物仿真平台研究了环路器件的非理想特性对预失真器性能的影响.给出了预失真器的模型及所用到的自适应算法，分析了这些器件的非理想特性以及它们对传输信号的影响，并通过测试平台评估了不同器件传输特性对信号邻信道功率比（ACPR）及误差向量幅度（EVM）的影响.结果表明非理想特性中相偏或相位抖动对系统影响较小，而IQ不均衡度大及量化位数少对系统性能有较大影响，并对硬件实现提出了一些有用的技术参数要求. 

Effect of Demodulation Loop Non-Ideal Characteristics on the Pre-Distortion System

In this paper, the effects of non-ideal characteristics of the loop devices on the performance of pre-distortion were studied using the semi-physical simulation platform. First, a pre-distortion model and adaptive algorithm to be employed were presented, and then non-ideal characteristics of these devices and their effects on the transmission signal were analyzed. The effects of the non-ideal characteristics of different components on the adjacent channel power ratio (ACPR) and error vector magnitude (EVM) of transmitted signal were evaluated through a practical experimental platform. The results show that phase offset and jitter have a small effect on the system performance, while larger IQ imbalance and small number of quantization bits can cause much performance degradation. Some useful technical requirements are given for implementation consideration as well.