Subcarrier dqpsk modulated optical wireless communications in atmospheric turbulence

Bit error rate (BER) performance is studied for a subcarrier differential quadrature phase-shift keying modulated optical wireless communication system over the Gamma-Gamma turbulence channels. A closed-form BER expression is derived using a series expansion approach. Asymptotic analysis shows that the diversity order of the considered system depends only on the smaller channel parameter.