RA 码及其在通信系统中的应用研究确良：重复累积码；简化译码算法；高斯估计；比特交织编码调制；光纤通 信；码率兼容码；Turbo 码交织器-RA Code and Its Application in Communication System does good: repeat accumulate codes simplify the decoding algorithm Gaussian estimation Bit-Interleaved Coded Modulation op