We propose and analyze an optimized Lambertian order (OLO) of light-emitting diode for both indoor cellular optical wireless communication and positioning systems. We carry out analysis for the system consisting of a Lambertian source and a tilted optical receiver, and develop an expression for OLO for four-, six-, and nine-cell configurations. We investigate the channel characteristics including the optical path loss, impulse response, transmission bandwidth, and positioning accuracy for the proposed systems with and without OLO, showing that there is a significant improvement in the transmission bandwidth as well as the positioning accuracy when employing OLO. For example, for a four-cell configuration with the optimum Lambertian order, 99% of cumulative distribution function of the estimation errors is within the Cramer–Rao bound (CRB) accuracy of 6.7 to 26.7 cm, compared to the CRB accuracy of 12.8 to 29.7 cm for the Lambertian order of m=1.
In this paper, two models for diffuse indoor cellular optical wireless communication (OWC) systems with and without a
holographic light shaping diffuser (LSD) are presented. For both models, the power distribution, the impulse response of
the channels and root mean square (RMS) delay are described and analyzed. We perform a computer simulation to
compare the channel characteristics of the typical indoor cellular OWC systems with that employing the holographic
LSD. The results show that the system with the holographic LSD provides a more uniform power distribution and a less
RMS delay spread for the same divergence angles.