Performance of subcarrier intensity modulated MIMO wireless optical communications

We study the error rate of a subcarrier intensity modulated multiple-input multiple-output wireless optical communication system employing phase-shift keying, differential phase-shift keying, and noncoherent frequency-shift keying over the Gamma-Gamma turbulence channels. Closed-form error rate expressions are derived using a series expansion approach. Truncation error analysis and asymptotic error rate analysis are also presented. Our asymptotic analysis shows that the diversity order of the system and the signal-to-noise ratio penalty factors for noncoherent modulations depend only on the smaller channel parameter. Furthermore, the signal-to-noise ratio penalty factors for noncoherent modulations can be improved using multiple-input multiple-output technique.