基于白光发光二极管室内可见光通信系统的调制带宽有限, 在调制带宽受限的条件下, 如何进一步提升通信速率成为研究难点。文章设计了一种多进制变幅度变周期的调制技术, 给出了调制符号结构及符号参数配置, 详细分析、对比了该调制方式与开关键控、脉冲位置调制和数字脉冲间隔调制方式的带宽需求、传输容量、平均发射功率和误包率。仿真结果表明, 相对于常用的数字基带调制方式, 多进制变幅度变周期的调制技术占用调制带宽低、符号传输容量高且无需符号同步, 提高了调制效率, 也有效地提高了系统的通信速率。

The modulation bandwidth of the white-light Light Emitting Diode (LED) indoor visible light communication system is limited. Under the condition that the modulation bandwidth is limited, how to further increase the communication speed becomes a hot research topic. A Multi-ary Variable Amplitude & Period Modulation(MVAPM) technique is designed. The modulation symbol structure and its symbol parameter configuration are given. The modulation methods based on On-Off Key (OOK), Pulse Position Modulation (PPM) and Digital Pulse Interval Modulation (DPIM) are analyzed and compared in terms of bandwidth requirements, transmission capacity, average transmit power, and packet error rate. The theoretical analysis and simulation results show that compared with the commonly used digital baseband modulation method, MVAPM has the characteristics of lower modulation bandwidth, higher symbol transmission capacity, symbol-free synchronization, higher modulation efficiency, which effectively improves the communication rate of the system.