Performance analysis of SFBC-FSTD in multiple-input single-output-VLC systems with co-channel interference

The authors investigate space frequency block code (SFBC) with frequency-switched transmit diversity (FSTD) in indoor visible light communications (VLCs) in order to mitigate the co-channel interference (CCI) through a cooperative transmission and thereby improve system reliability. In addition, the authors explore the influence of parameters, the semi-angle at half power and the position of the light emitting diodes (LEDs), on the bit error rate (BER) performance. Although VLC is a promising technology for indoor wireless communications, it is necessary to cope with the CCI that occurs when the coverage areas of multiple LEDs overlap and the LEDs are sending different signals. The desired signal experiences serious interference from other LEDs to the point that it is impossible to recover the signal without coding. They investigate SFBC-FSTD in a multiple-input single-output-VLC system composed of four LEDs and one photodiode. It is effective in this scenario because the data rate is not affected by the code rate. Through computer simulations, SFBC-FSTD exhibits great improvement in the BER performance, requiring a lower signal-to-noise ratio than SFBC and single-input single-output. Furthermore, SFBC-FSTD is more power efficient.