PERFORMANCE ANALYSIS OF MULTILEVEL CODING SCHEME FOR RAYLEIGH FADING CHANNEL WITH GAUSSIAN-NOISE

To evaluate the coding performance of a multilevel coding scheme for R ayleigh fading channel, a virtual automatic gain control and interleav ing are applied to the scheme. The automatic gain control is assumed o nly for the theoretical evaluation of the performance. It is noted tha t the bit error-rate performance of the scheme for phase shift keying does not change whether the control is assumed or not. By the effect o f the virtual automatic gain control and the interleaving, a fading ch annel with Gaussian noise is theoretically converted into an equivalen t time-invariant channel with non-Gaussian noise. The probability dens ity function of the converted non-Gaussian noise is derived. Then, the function is applied to a formula of the bit error-rate of the scheme for non-Gaussian noise. The formula is derived for phase shift keying by modifying that for pulse amplitude modulation. The coding performan ce for the non-Gaussian noise channel is evaluated by the formula, and the suitable coding with ideal interleaving is searched. As a result, the coding gain of 28 dB is obtained at the bit error-rate of 10(-6) by using BCH code of length 31. This result is confirmed by a simulati on for the fading channel. Then, the effectiveness of the formula for finite interleaving is evaluated. Finally, the usefulness of the formu la, where the noise power is doubled, is shown for a case of a differe ntial detection.