A novel Hartley-based U-OFDM dimming control approach

A novel Hartley-based Unipolar orthogonal frequency division multiplexing (HU-OFDM) approach is proposed for visible light communication systems (VLC) with dual function i.e. illumination and communication, in which the fast Hartley transform (FHT) is exploited for the modulation/demodulation processing instead of the conventional fast Fourier transform (FFT) to generate real and positive OFDM symbols transmitted by intensity modulation/direct detection (IM/DD) in an optical link. The FHT-based solution without DC bias adding and Hermitian symmetry constrain has the advantage of lower computational complexity and hardware cost in contrast to those conventional OFDM approaches. Furthermore, by introducing the HU-OFDM into VLC based on pulse width modulation (PWM), a kind of dimming control scheme with power and spectral efficiency for VLC can be obtained. The system performance is also assessed in terms of dimming functionality and BER respectively. The simulation results show that the HU-OFDM dimming control scheme could achieve a wide dimming range in the mean time without sacrificing the BER performance.