基于三种调制模式下的turbo码光无线通信系统分析

从分析大气对光无线通信系统的影响出发,研究了大气信道特性,建立了大气信道信噪比和能见度的关系.为降低系统误码率,提出了基于OOK、BPSK、BPPM三种调制模式的turbo码的编码方案,推导出三种不同方案对应的turbo码迭代MAP算法.应用建立的信噪比关系,分析和计算了基于三种不同方案的系统的误码率.结果表明,基于BPSK的turbo码系统比OOK和BPPM系统的信噪比降低约3dB,且在高的信噪比情况下,BPSK系统能显著降低系统的误码率.因此,基于BPSK的turbo码方案较适合光无线通信系统.

Analysis of Turbo Coded Optical Wireless Communication Based on Three Different Modulated Modes

The atmospheric influence on optical wireless communication system and the character of atmospheric channel were analyzed, and the signal-to-noise ratio of atmospheric channel versus the weather visibility was deduced. In order to decrease the bit-error-rate of system, the scheme of system based on turbo code of OOK, BPPM and BPSK was proposed, and three different iterated MAP algorithm of turbo code were deduced. Apply to the function of SNR, the BER of system based on three schemes were analyzed and calculated. The results show that the scheme of turbo code based on BPSK can degrade SNR 3 dB compared with that of BPSK and BPPM, and the scheme of BPSK is efficient to degrade the BER of system when the SNR is high. So the turbo coding scheme based on BPSK is very suitable for the optical wireless system.