Alamouti coding for indoor optical wireless communications using ACO-OFDM

This paper describes the use of Alamouti coding in indoor optical wireless systems using asymmetrically clipped optical OFDM. The performance is compared with systems in which the same signal is simultaneously transmitted from both transmitters. Expressions are calculated for the signal to noise ratio as a function of distance between the transmitters and receivers for the case where there is line of sight between transmitters and receivers. It is shown that while the performance of Alamouti coding is independent of the difference in delay for the two paths, the performance of repetition coding depends on the delay and the OFDM subcarrier frequency.