Mobile Multigigabit Indoor Optical Wireless Systems Employing Multibeam Power Adaptation and Imaging Diversity Receivers

In this paper, we introduce two novel methods (beam power adaptation and diversity imaging) to the design of optical wireless systems to improve link performance. The aim is to reduce the effect of intersymbol interference and to enhance the signal-to-noise ratio (SNR), thus enabling the system to achieve mobility while operating at high bit rates. In good agreement with previous work, the results show that the imaging conventional diffuse system (CDS) with maximum ratio combining (MRC) offers 20 dB better SNR than the nonimaging CDS. The new adaptive line strip multibeam system (ALSMS) with a new imaging diversity receiver provides an SNR improvement of 39 dB over the imaging diversity CDS when both systems employ MRC and operate at 30 Mbits/s. This result illustrates the SNR improvement achieved through the use of our adaptive algorithm coupled with spot diffusing. The lower bit rate (30 Mbits/s) facilitates comparison with previous work. The results also indicate that the combination of transmit power adaptation and spot diffusing coupled with imaging diversity receivers can enable fully mobile 2.5 Gbit/s optical wireless communication. Such a 2.5 Gbit/s system (imaging MRC ALSMS) achieved an SNR improvement of 27 dB over a lower data rate (30 Mbits/s) nonimaging CDS.