Effect of LED emission cross-section in indoor visible light communication systems

Abstract

Visible light communication (VLC) is an optical wireless communication technology that uses visible light emitting diodes (LEDs) as a communication source. Since the LEDs are also used for illumination, the cross-section emission effects of the LEDs need to be analyzed as they apply to indoor VLC channels. In order to evaluate the illumination and communication performance according to the emission cross-section pattern a simple LED model with a quasi-elliptic emission cross-section is proposed and compared to a circular LED model. The spatial distributions of the received optical power and root mean square delay spread are analyzed through calculation and comparison. The LEDs with a quasi-elliptic emission cross-section provide less fluctuation in the illumination and optical power distribution at the receiving plane. However, the RMS delay spread increases and subsequently the maximum data rate decreases for the quasi-elliptic emission cross-section LEDs. The single transmitter VLC system is found to support at least 17 and 24 Mb/s for circular and quasi-elliptic emission cross-section LEDs for the entire receiving plane, respectively. The four-transmitter VLC system is found to support at least at 30 and 33 Mb/s for circular and quasi-elliptic emission cross-section LEDs for the entire receiving plane, respectively. © 2012 Nguyen et al.; licensee Springer licensee InTech.