Exact BER analysis of subcarrier QAM and PSK intensity modulations in strong turbulence

Bit-error rate analysis is investigated for subcarrier intensity modulations employing general order rectangular quadrature amplitude modulation and M-ary phase-shift keying over the K-distributed strong turbulence channels. Bit-error rate expressions are derived using a series expansion of the modified Bessel function of second kind and a moment generating function approach. Truncation error analysis and asymptotic bit-error rate analysis are also presented. Our asymptotic bit-error rate analysis reveals that the diversity order of the subcarrier intensity modulations over the K-distributed turbulence channels is 0.5. Numerical results demonstrate that our series based bit-error rate expressions are highly accurate and efficient.