伪随机调制序列的CP-EBPSK通信系统

为了紧缩通信系统的信号频谱,减少其线谱能量,引入了一种伪随机序列调制方法.该方法通过对连续相位扩展的二元相移键控(CP-EBPSK)通信系统进行改进,使发射端键控调制时段的相位变化受控于伪随机序列,从而使CP-EBPSK调制指数的符号随机化,同时保持CP-EB-PSK通信系统其他组成部分不变.仿真结果表明,该方法可使调制信号占用的带宽仅为CP-EB-PSK通信系统带宽的一半,显著提高了频谱的利用率.即使在-60 dB带宽的苛刻要求下,当信号载频分别为30 MHz和2.4 GHz时,伪随机序列调制的CP-EBPSK通信系统以约35 dB的信噪比为代价,获得超过200 bit/(s.Hz)的频谱利用率,大幅度紧缩了频谱,提高了系统整体性能.同时,接收机冲击滤波器的特殊滤波效果导致解调器可不受调制符号随机化的影响,从而使得解调器的解调性能基本不变.

Pseudo-random modulated CP-EBPSK communication system

To tighten the signal spectrum of a communication system and reduce the spectral energy,a pseudo-random modulation method is introduced.In this method,the continue phase extended binary phase shift keying(CP-EBPSK) communication system is modified to make the phase changes of the transmitter’s modulation to be controlled by the pseudo random sequence.The symbols of the modulation indexes of the CP-EBPSK are randomized while the other parts of the CP-EBPSK communication system keep unchanged.The simulation results show that by this method the bandwidth occupied by the modulation signal is half of that of the primitive CP-EBPSK communication system,and the spectrum efficiency is remarkably improved.Even in the harsh condition of the-60dB bandwidth,when the carrier frequencies are 30MHz and 2.4 GHz,the spectrum efficiency of the non-coding pseudo-random modulated CP-EBPSK communication system is more than 200bit/(s·Hz) at the cost of about 35dB signal-to-noise ratio and the spectrum is narrowed,which improve the system’s overall performance.Besides,the special filter effect of the impact filter in receivers makes the demodulator free from the influence of the randomization of the modulation symbols,which keeps the demodulation performance unchanged.