Adaptive Sigma Delta Modulators for Fading Channels

In this paper we present a single loop higher order sigma delta modulator with adaptive input gain to the fading channel variation. The power of the received signal is measured periodically in block of samples to determine the fading level and corresponding gain values are used to compensate for the effect of the fading channel. The signal is multiplied with the chosen gain to achieve the approximately constant signal level while meeting the stability requirement of the modulator. The results show that the proposed adaptive system significantly outperforms the fixed gain modulator in terms of the bit error rate (BER).