155Mbps毫米波QAM解调器设计

Design of 155Mbps Millimeter-Wave QAM Demodulator

针对数字毫米波通信设计了一个155Mbps QAM解调器.为比较大容量毫米波通信中峰均比、解调门限和带宽对系统性能的影响,提出了一个新的参量——信号资源优化系数η,根据4-1024 QAM的η值优选了QPSK、16QAM和64QAM作为调制方式.研究了AGC和载波泄露对解调性能的影响;根据小滚降系数奈奎斯特升余弦信号的数字预滤波原理,提出了一种零抖动定时误差检测方法;研究了PFD载波恢复算法在解调高阶QAM信号时出现的星座点捕获错误问题,提出了根据星座点功率自适应调整捕获门限的改进PFD算法.本设计已成功应用于一毫米波链路,算法工作稳定,在比特误码率为1E-8时,解调损失小于2dB.

A 155Mbps QAM demodulator is designed for digital millimeter-wave communication.A novel parameter named signal resource quantity（SRQ） incorporating peak and average power ratio,demodulation threshold and bandwidth was introduced to find out the best order of QAM for high-speed millimeter-wave communication.The 4～64QAMs win in 4～1024QAMs according to their SRQs.How gain deviation of AGC and carrier leakage affect the demodulation performance were studied.A zero-jitter timing recovery detector was implemented by the theories of pre-filtering Nyquist raised sine signal with small roll-off factor.An improved PFD carrier recovery algorithm with adaptive power threshold was proposed to avoid wrongly capturing constellation points in the case of high-order QAM.The design has been applied to a millimeter-wave link successfully,and the algorithms work robustly.The demodulation loss was less than 2dB when the BER was equal to 1E-8.