具有连续相位的8PSK调制  

8PSK Modulation With Continuous Phase

作　　者：琚瑛珏[1,2] 朱江[1] 付永明[1] 

机构地区：[1]国防科技大学电子科学与工程学院 [2]解放军61062部队

出　　处：《信号处理》2011年第10期1571-1575,共5页Journal of Signal Processing

摘　　要：连续相位的QPSK信号具有恒定包络,这解决了传统QPSK信号由于相位跳变带来的包络起伏问题,但其频带利用率没有8PSK高,为提高频带利用率,提出了连续相位8PSK(CP8PSK)调制。本文首先将8PSK表示为连续相位调制(CPM)的形式,然后利用差分编码来表征一个符号周期的相位变化,再使用频率脉冲对其相位进行脉冲整形,得到连续相位,最终得到CP8PSK。为了降低系统的整体复杂度,本文还对CP8PSK进行了Laurent分解。根据理论分析CP8PSK信号应当具有恒定包络,而且比连续相位的QPSK调制要有更高的带宽效率和更平滑的频谱,通过MATLAB进行仿真之后,得到的CP8PSK具有恒定包络,且带宽效率在同等情况下要高于整形的交错QPSK(SOQPSK)和8PSK,频谱也更加平滑,抗误码性能与理想8PSK相比损失也不大。QPSK signal which has continuous phase solves the issue of envelope fluctuations bought by phase jump,but its bandwidth efficiency is lower than conventional 8PSK.To improve the bandwidth efficiency,the continuous phase 8PSK（CP8PSK） is proposed.After representing 8PSK signal as continuous phase modulation（CPM）,differential coding rule is used to indicate the phase change in one symbol,then pulse shaping method is used to shape the phase,which makes the phase continuous,finally,the CP8PSK expression is concluded.In order to reduce the system＇s complexity,Laurent decomposition of CP8PSK is deduced.Theoretical analysis proves that CP8PSK signal has constant envelope,and has higher bandwidth efficiency,better power spectrum than QPSK signal which has continuous phase.Matlab simulation results also show that CP8PSK signal has constant envelope and has higher bandwidth efficiency, more smooth power spectrum than shaped offset QPSK（SOQPSK） and 8PSK in the same condition,and the probability of symbol error of CP8PSK is little worse than the theoretical value of 8PSK.

关 键 词：连续相位调制 恒定包络 带宽效率 脉冲整形方法 LAURENT分解 

分 类 号：TN911[电子电信—通信与信息系统]