Adaptive Transmitter Regulation for Linear Optical Wireless Communications

Over the last decade, higher and higher record data rates have been demonstrated in the field of optical wireless communications (OWC) by using modulation schemes like orthogonal frequency-division multiplexing (OFDM). Record-breaking transceivers are optimized for peak data rate but feature drawbacks like a low link range, which makes them impractical for real-world scenarios. This work introduces an adaptive transmitter (ATX) that solves the trade-off between the peak data rate and the link range by a control of the transmission power depending on tolerable nonlinear distortions. We prove the concept with a bidirectional transceiver with off-the-shelf LEDs and demonstrate a range improvement by a factor of 3.8 from 3.3 m to 12.5 m, compared to a transmitter with fixed power and a peak data rate of 1.23 Gbit/s. In our experiment, we employ DC-bias optical OFDM (DCO-OFDM), but the approach is compatible with other linear modulation schemes and faster emitters to reach even higher data rates. The implementation requires at least a digital-to-analog converter (DAC). Thereby, the ATX can bring systems with record data rates into practical applications.