为提高随机极性的修正连续相位扩展二元相移键控(MCP-EBPSK)调制信号的传输性能,对比了AWGN信道上自适应门限判决、BP神经网络和支持向量机(SVM)判决3种解调方式的解调性能,并引入了RS码和规则LDPC码来进行改善.根据随机极性MCP-EBPSK调制原理和数字冲击滤波器特殊滤波机理,设计了基于自适应门限判决、BP神经网络和SVM的解调器.同时,在这3种解调方式性能均不佳时,对RS码和规则LDPC编码的随机极性MCP-EBPSK传输性能进行了仿真.仿真结果表明:在AWGN信道上,自适应门限判决、BP神经网络和SVM三种解调方式的解调性能相差不大;当采用自适应门限判决且误码率为10-4时,RS码和规则LDPC码的编码增益分别约为4 dB和7 dB.因此,引入信道编码可显著改善随机极性MCP-EBPSK的传输性能.
In order to improve the transmission performance of random polar and modified extended binary phase shift keying with continuous phase(MCP-EBPSK) modulated signal,the demodulation performance of the adaptive threshold discrimination,BP neural network,and support vector machine(SVM) in additive white Gaussian noise(AWGN) channel is compared,then Reed-Solomon(RS) code and regular low-density parity-check(LDPC) code are introduced.According to the principle of MCP-EBPSK with random polar and the special filtering mechanism of digital impacting filter,the demodulators are designed based on adaptive threshold discrimination,BP neural network,and SVM.Meanwhile,when the demodulation performance of these demodulators is poor,the RS and regular LDPC coded MCP-EBPSK with random polar is also simulated.Simulation results show that in AWGN channel,the demodulation performance of adaptive threshold discrimination,BP neural network and SVM is almost the same;when adaptive threshold discrimination is used and BER is 10-4,the coding gain of RS code and regular LDPC is about 4 dB and 7 dB,respectively.Therefore,channel code can be introduced to significantly improve the transmission performance of MCP-EBPSK with random polar.