LTE-U终端发射机信号EVM测量算法研究

EVM Measurement Algorithm of LTE-U Terminal Transmitter Signal

针对LTE-U协议的PUSCH(上行业务信道),提出了一种有效的EVM算法,可以简单、快速、精确地测量EVM。该算法中,对解调前的数据定时同步后直接进行频偏、相偏与I/Q不平衡参数的估计与补偿,以减小测量信号误差,再经过解调与再调制准确恢复参考信号,并最终实现EVM的测量。仿真和实验结果表明,该算法EVM的仿真结果与理论值接近,可满足测试的精度要求,可以为LTE-U射频一致性测试系统提供理论基础。

Aiming at the PUSCH(uplink traffic channel)of the LTE-U protocol,an effective EVM(error vector magnitude)algorithm is proposed,which can easily,quickly and accurately measure EVM.In this algorithm,the frequency offset,phase offset,and I/Q imbalance parameters are estimated and compensated directly after timing synchronization of the data before demodulation to reduce the measurement signal error.Then,the demodulation and re-modulation accurately recover the reference signal,and finally realize the measurement of EVM.Simulation and experimental results indicate that the simulation results of the algorithm EVM are close to the theoretical values,which can meet the test accuracy requirements,and can provide a theoretical basis for the LTE-U RF compliance test system.