Adaptive 2.5 Gbit/s Optical Wireless Systems Employing a Two Dimensional Beam Clustering Method and Imaging Diversity Receivers

In this paper, we propose and evaluate a novel optical wireless (OW) configuration that employs a two dimensional adaptive beam clustering method (2DABCM) in conjunction with imaging diversity receivers. Our goal is to reduce the effect of intersymbol interference and to improve the signal-to-noise ratio (SNR) when the system operates under the constraints of background noise (BN) and multipath dispersion. In the conventional diffuse system, an SNR improvement of 22 dB and an increase in the bandwidth from 38 MHz to 200 MHz approximately, is achieved when an imaging receiver is implemented. Furthermore, the new methods introduced (transmit power adaptation, beam clustering, and diversity imaging) increase the bandwidth from 38 MHz to 5.56 GHz. Previous optical wireless systems operated typically at 30 to 100 Mbit/s and here we report a system that operates at 2.5 Gbit/s. Our results indicate that the new 2.5 Gbit/s 2DABCM transmitter with a new imaging diversity receiver (with select best (SB)) demonstrates an SNR improvement of 16 dB over the non-imaging CDS system operating at 30 Mbit/s. The results also show that the proposed system (imaging 2DABCM at a bit rate of 2.5 Gbit/s) produces an SNR improvement of 10 dB when maximum ratio combining (MRC) replaces SB.