Group waveform-coded pulse width position modulation(PWPM) for vehicular visible light communications

We propose a new VLC scheme based on group waveform-coded pulse width position modulation for vehicular visible light communications. Proposed modulation scheme can determine two groups of waveform-coded signal. Then, each multi-level value of waveform-coded signal is converted to pulse width and position which results in not only an improved data rate, but also a processing gain in reception. In addition, by introducing average duty ratio and cyclic shift concept in PWM, dimming for LED light illumination can be supported without any degradation in performance. We show the availability of our proposed method through simulation results under the vehicular channel environment.