PERFORMANCE EVALUATION OF FSK AND CPFSK OPTICAL COMMUNICATION-SYSTEMS- A STABLE AND ACCURATE METHOD

The modified moments method for evaluating the performance of coherent optical FSK and CPFSK systems is presented. Since the classical proce dure becomes ill-conditioned as the order of the moments increases, we consider the construction of Gaussian quadrature rules (GQR) from the modified moments, The analysis accounts for the influences of IF band width, transmitter and local oscillator laser phase noise, postdetecti on filters, and additive Gaussian noise. It is found that the proposed approach is a highly reliable and efficient method for calculating th e error probability. A comparison with results obtained from the Gauss ian quadrature rule, Gaussian approximation method, and analytical app roximation formulas shows that this technique is very accurate. Analyt ical expressions are derived for FSK and CPFSK receivers which include polarization and phase diversity techniques. The use of numerical pro gramming to avoid many unnecessary computations is discussed. This eva luation method can be used to account for the effects of crosstalk in multichannel systems and the influence of error-control codes.