弱湍流信道中的调制技术  

Modulation Technologies under Weak Atmospheric Turbulence Channel

作　　者：贾科军[1] 薛建彬[1] 彭铎[1] 张玺君[1] 

机构地区：[1]兰州理工大学计算机与通信学院,甘肃兰州730050

出　　处：《中国激光》2009年第3期569-573,共5页Chinese Journal of Lasers

摘　　要：基于弱湍流的无线光通信系统信道模型,对开关键控(OOK)、脉冲位置调制(PPM)、差分脉冲位置调(DPPM)、数字脉冲间隔调制(DPIM)和双头脉冲间隔调制(DH-PIM)调制方式的符号结构、发射功率、传输带宽以及误包率进行了理论推导和对比分析。结果表明,PPM必须需要符号同步和时隙同步,而DPIM、DPPM、DH-PIM调制只要求时隙同步。OOK的平均发射功率最大,PPM的平均发射功率最小,DH-PIM比OOK小但是比DPIM和DPPM大,DPIM发射功率特性略优小于DPPM。当M=6时与OOK调制平均发射功率比较,PPM调制节约功率约15 dB,DPPM和DPIM调制节约功率约12 dB,当α=2时DH-DPIM调制节约功率约10 dB。OOK带宽需求最小,PPM带宽需求最大,DPIM的带宽特性略大于DPPM,DH-PIM带宽需求大于OOK但小于DPPM。当M=6时与OOK带宽比较,PPM带宽需求约为OOK的11倍,DPPM和DPIM的带宽需求约为OOK的6倍,当α=2时DH-DPIM带宽需求为OOK的3倍。在相同平均背景光子和相同平均光脉冲接收光子的条件下PPM、DPIM、DPPM、DH-PIM和OOK调制方式的误包率依次增大。Based on the model of wireless optical communication system channel under weak atmospheric turbulence, theoretically deduction and comparatively analysis are done on modulation symbol structure, transmission power, bandwidth requirement and packet error rate of the five digital modulation schemes (OOK, PPM, DPPM, DPIM and DH-PIM). The results show that PPM need both symbol and slot synchronization, while DPIM, DPPM and DH-PIM just need slot synchronization. OOK offers the biggest average transmission power, while PPM offers the smallest transmission power, the average transmission power of DH-PIM is smaller than that of OOK, while bigger than that of DPIM and DPPM. And the transmission power characteristic of DPIM is slightly smaller than that of DPPM. When M=6, comparing to average transmission power of OOK modulation scheme, PPM can save about 15 dB, DPPM and DPIM can save 12 dB, DH-DPIM can save about 10 dB with α=2. OOK offers the smallest bandwidth requirement, while PPM offers the biggest bandwidth requirement, the bandwidth requirement of DPIM is slightly bigger than that of DPPM. And the bandwidth requirement of DH-PIM is bigger than that of OOK, while smaller than that of DPPM. When M=6, the bandwidth requirement of PPM modulation is eleven times of that of OOK, and that of DPPM and DPIM is six times of OOK, that of DH-DPIM with α=2 is three times of OOK. Under the condition of the same mean number of absorbed background photons and the same mean number of absorbed signal photons per pulse, the packet error rates increase in order of PPM, DPIM, DPPM, DH-PIM and OOK.

关 键 词：无线光通信 调制技术 弱湍流信道 误包率 

分 类 号：TN929.12[电子电信—通信与信息系统]