10 Gb/s Indoor Optical Wireless Systems Employing Beam Delay, Power, and Angle Adaptation Methods With Imaging Detection

In this paper, we propose a mobile optical wireless system that employs beam delay adaptation, and makes use of our previously introduced beam angle and power adaptation multi-beam spot diffusing configuration in conjunction with an imaging receiver. Our ultimate goal is to improve the bandwidth, reduce the effect of intersymbol-interference, and increase the signal-to-noise ratio (SNR) when the transmitter operates at a higher data rate under the impact of multipath dispersion, background noise, and mobility. A significant reduction in the delay spread can be achieved compared to a conventional diffuse system (CDS) when an imaging receiver replaces a nonimaging receiver at the room´s corner, where the delay spread is reduced from 2.4 ns to about 0.35 ns. Our proposed system, beam delay, angle, and power adaptation in a line strip multibeam spot diffusing configuration (BDAPA- LSMS), offers a reduction in delay spread by a factor of more than 10 compared with only the beam angle and power adaptation LSMS. An increase in channel bandwidth from 36 MHz (CDS) to about 9.8 GHz can be achieved when our methods of beam delay, angle, and power adaptation coupled with an imaging receiver are employed. These improvements enhance our system and enable it to operate at a higher data rate of 10 Gb/s. At a bit rate of 30 Mb/s, our proposed BDAPA-LSMS achieves about 50 dB SNR gain over conventional diffuse systems that employ a nonimaging receiver (CDS). Moreover, our simulation results show that the proposed BDAPA-LSMS at a bit rate of 10 Gb/s achieves about 32.3 dB SNR at the worst communication path under the presence of background noise and mobility while achieving a bit error rate below 10^-9.