Low-Complexity Layered ACO-OFDM for Power-Efficient Visible Light Communications

Commercially available LED luminaires demand both low-complexity and high power efficiency from visible light communication (VLC) deployments. Layered asymmetrically clipped optical orthogonal frequency division multiplexing (LACO-OFDM) is attracting increasing interest due to the high spectral efficiency and high power efficiency. However, these advantages come at the price of high computational complexity at both transmitter and receiver. In this paper, we propose a low-complexity LACO-OFDM (L-LACO) to generating identical signals to conventional systems while employing a half-size IFFT/FFT and possessing low implementation complexity. The required number of real-valued multiplication operations and real-valued addition operations are quantified and compared to conventional LACO-OFDM. The saved power corresponding to the reduction in arithmetic operations is also estimated, which is shown to increase logarithmically with number of subcarriers, and to increase linearly with modulation bandwidth. Numerical results show that the proposed L-LACO requires about half the number of arithmetic operations as LACO-OFDM for both the transmitter and the receiver. The BER performance of L-LACO is estimated by Monte Carlo simulations under a VLC line-of-sight (LOS) channel and under a VLC dispersive channel that is shown to be identical to LACO-OFDM.