Subcarrier intensity modulated optical wireless communications in atmospheric turbulence with pointing errors

An optical wireless communication system using subcarrier intensity modulation is analyzed for gamma-gamma turbulence channels with pointing errors. We study the error rate performance of such a system employing M-ary phase-shift keying, differential phase-shift keying, and noncoherent frequency-shift keying. Highly accurate error rate approximations are derived using a series expansion approach. Furthermore, outage probability expressions are obtained for such a system. Asymptotic error rate and outage probability analyses are also presented. Our asymptotic analysis reveals some unique transmission characteristics of such a system. Our findings suggest that pointing error compensation is necessary as pointing errors can severely degrade the error rate and outage probability performance of an uncompensated system.