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针对脉冲位置调制(PPM)和数字脉冲间隔调制(DPIM)等方法存在的问题,提出了一种新的双宽脉冲位置调制(DD-PPM)方式。在给出其符号结构的基础上,分析了带宽需求、传输容量和平均功率,推导出弱湍流信道下的误包率模型,并将其与开关键控调制(OOK),PPM和DPIM等典型调制方式进行了比较。理论分析和仿真结果表明,DD-PPM不仅比OOK具有更高的功率利用率和更好的差错性能,比PPM具有更高的带宽效率和传输容量,比DPIM具有相近甚至略好的差错性能,而且因符号长度固定,解调时不存在等待或缓存器溢出等问题,较DPIM更易工程实现。因而作为一种折中的调制方式,DD-PPM在无线光通信中有一定的应用场合。
Aiming at the existing problems of pulse position modulation (PPM) and digital pulse interval modulation (DPIM), a new double-wide pulse position modulation (DD-PPM) method is proposed. Based on the symbol structure, the bandwidth demand, transmission capacity and average power are analyzed, and the packet error rate model is deduced under weak turbulence channel, and then compared with OOK, PPM and DPIM Modulation is compared. The theoretical analysis and simulation results show that DD-PPM not only has higher power efficiency and better error performance than OOK, but also has higher bandwidth efficiency and transmission capacity than PPM and has similar or even slightly better error performance than DPIM. Moreover, because of the fixed length of the symbol, there is no problem of waiting or buffer overflow when demodulating, which is easier to implement than DPIM. Therefore, as a compromise modulation method, DD-PPM has certain applications in wireless optical communications.