Abstract
Over the last two decades, indoor optical wireless (OW) systems have operated typically at 30 Mbit/s to 155 Mbit/s. Here, we propose and evaluate for the first time a mobile OW system that operates at 5 Gbit/s and 10 Gbit/s. The improvements in data rates and channel bandwidth are achieved through the introduction of three approaches: angle diversity, beam angle and beam power adaptation. We propose a mobile OW system that employs beam angle and beam power adaptation in a line strip multibeam spot diffusing system configuration in conjunction with an angle diversity receiver (APA-LSMS) to mitigate the degradation due to ambient light noise, multipath dispersion and mobility. The performance of our proposed system was investigated through channel and noise modelling. Our results show that the proposed APA-LSMS at a bit rate of 30 Mbit/s achieves about 45 dB signal-to-noise ratio (SNR) gain over a power adaptive line strip multibeam system (PA-LSMS) and offers 60 dB SNR gain over a conventional diffuse system (CDS) at a 6 m horizontal separation between the transmitter and the receiver. The SNR is independent of the transmitter location and when our methods (angle diversity, beam angle and beam power adaptations) are implemented, the SNR can be maximized at the receiver for every transmitter location. The results show an increase in channel bandwidth from 36 MHz (CDS) to approximately 7.2 GHz in our proposed system (APA-LSMS). These improvements enhance our system and enable it to operate at higher data rates of 5 Gbit/s and 10 Gbit/s.