Interference aspects of adaptive modems over slow Rayleigh fading channels

Adaptive modulation can achieve channel capacity gains by adapting the number of bits per transmission symbol on a burst-by-burst basis, in harmony with channel quality fluctuations. This is demonstrated in the paper for target bit error rates of 1 and 0.01%, respectively, in comparison to conventional fixed modems. However, the achievable gains depend strongly on the prevalent interference levels and hence interference cancellation is invoked on the basis of adjusting the demodulation decision boundaries after estimating the interfering channel's magnitude and phase. Using the modem-mode switching levels of Table X and with the aid of interference cancellation, target BERs of 1 and 0.01% can be maintained over slow-fading channels for a wide range of channel signal-to-noise ratios (SNR) and signal-to-interference ratios (SIR).