针对脉冲位置调制(PPM)和数字脉冲间隔调制(DPIM),以及定长数字脉冲间隔调制(FDPIM)等方法存在的问题,提出了一种新的双脉冲间隔调制(DP-PIM)。在给出其符号结构的基础上,分析了带宽需求、传输容量和平均发射功率,推导出了弱湍流信道下的误包率模型,并与PPM,DPIM,FDPIM和开关键控(OOK)调制等方法进行了比较。结果表明,DP-PIM不仅比FDPIM和PPM显著缩短了符号长度,提高了带宽效率和传输容量,而且与DPIM,双头脉冲间隔调制(DH-PIM)和双幅度脉冲间隔调制(DAPIM)一样具有内置符号同步能力,同时通过固定符号长度,克服了缓存器可能出现的冗位或溢位等问题,因而在无线光通信系统中将具有一定的应用前景。

A new modulation scheme called dual pulse-pulse interval modulation (DP-PIM) is proposed for optical wireless communication systems by resolving the problems which exist in fixed-length digital pulse interval modulation (FDPIM),pulse position modulation (PPM),and digital pulse interval modulation (DPIM). Based on given symbol structure,bandwidth requirement,average transmission power and capacity are studied. Meanwhile,the packet error rate is derived based on weak turbulence channel model. After compared with on-off keying (OOK),PPM,DPIM and FDPIM,the theoretical and simulation results show that DP-PIM has no problem such as overflow and underflow in the buffer by fixing the symbol length. DP-PIM also has built-in symbol synchronization as same as DPIM and FDPIM,meanwhile offers higher bandwidth efficiency and transmission capacity by reducing the average symbol duration for the given parameters. Hence,DP-PIM is superior in optical wireless communication systems.