Effect of data asymmetry on unbalanced QPSK signals with noisy phase reference

The combined effects of data asymmetry and a noisy carrier phase reference on the bit error rate performance of an unbalanced QPSK system are examined. The results are presented in terms of the SNR loss for a nominal error rate of 0.00001, parameterized by the mean and variance of the reference phase error at the receiver. The effect of asymmetry on the carrier tracking loop is not included. The results show a considerable sensitivity in performance of both channels to asymmetry, the lower data rate channel being, as expected, more prone to degradation.