DC-informative modulation for visible light communications under lighting constraints

Visible light communication employs low-cost intensity modulation and direct detection, where positive time-domain baseband signals are generated to drive LEDs through addition of a DC bias. However, the non-informative bias in this straightforward and easy-to-implement approach significantly reduces the system energy efficiency. In this article, new energy-efficient modulation schemes leveraging informative DC-bias are introduced. Under some lighting constraints, a convex optimization problem is formulated. Optimal constellations are constructed in either the time domain or frequency domain by compact sphere packing. Several DC-informative system architectures are then discussed. Finally, technical implementation challenges are investigated.