无线光通信双幅度脉冲位置调制

无线光通信脉冲位置调制(PPM)的功率利用率虽然很高,但带宽需求也非常高,在无线光通信系统中,应当充分考虑带宽需求和功率利用率的平衡问题。针对该问题,提出了一种新的双幅度脉冲位置调制(DAPPM)。在给出了其符号结构之后,分析了其带宽利用率。然后,推导了弱湍流信道模型下DAPPM的误时隙率和误包率,并与OOK、PPM、DPIM和DAPIM等调制方式进行了比较。结果表明,在相同的位分辨率条件下,DAPPM的误包率虽然高于PPM和DPIM,但明显优于OOK和DAPIM。同时,DAPPM去除了PPM中冗余的时隙,且平均长度比DPIM短,从而获得了比DPIM更高的带宽利用率。

A Novel Low Density Parity Check Coded Differential Amplitude and Pulse Position Modulation Free-Space Optical System for Turbulent Channel

Based on the proposed partly equidifferent mapping and its specific Differential Amplitude and Pulse Position Modulation(DAPPM) demodulation, a modified FSO scheme for turbulent channel is designed and analyzed. The novel Low Density Parity Check(LDPC) coded 4×4 and 4×8 DAPPM Free-Space Optical communication(FSO) system is constructed. The Monte Carlo simulation results show approximately 2d B transmit power reduction against classical LDPC-DAPPM at the identical Bit-Error-Rate in strong turbulent channel. The proposed partly equidifferent mapping is compatible with other modulations, so it enables widespread adoption in other coded FSO systems.