Improving Bandwidth Efficiency of Indoor Visible Light Communication by M-ary Return-to-zero Optical Pulse Amplitude Modulation

In order to solve the limitation of data rate caused by long rise and fall time of light emitting diodes, m-ary return-to-zero optical pulse amplitude modulation is proposed in this paper for improving the bandwidth efficiency of indoor visible light communication. M-ary return-to-zero optical pulse amplitude modulation transmits information through a subtle change of illumination intensity and supports both flicker mitigation and dimming control functions. An indoor communication link establishing process is introduced as a parameter training method based on the principle of successive approximation. Theoretical analysis shows that, m-ary return-to-zero optical pulse amplitude modulation can be used to achieve higher bandwidth efficiency without sacrificing the symbol error rate and bit error rate performance of an indoor visible light communication system. When the ratio of a_slot-a_BS is 0.1, then m-ary return-to-zero optical pulse amplitude modulation can provide 1.47 times bandwidth efficiency than that of on-off keying, 3.5 times than that of digital pulse interval modulation and 5.9 times than that of pulse position modulation. M-ary return-to-zero optical pulse amplitude modulation can be used as a candidate bandwidth efficiency modulation scheme to improving data rate of an indoor visible light communication system.