A modified constant modulus algorithm (CMA) for joint blind and carrier recovery in two-dimensional digital communication systems

The conventional constant modulus algorithm (CMA) requires a separate carrier recovery system (for example, a phase-locked loop) for phase recovery. This paper analyzes a modified CMA (MCMA) for blind equalization in QAM communication systems. The results indicate that the MCMA alone may be able to remove inter-symbol interference (ISI) and simultaneously correct the phase error because it implicitly incorporates a phase-tracking loop, which automatically recovers carrier phase. Consequently, it may outperform the conventional CMA in terms of convergence speed and residual ISI while both algorithms require an almost identical computational cost.