Constant modulus blind equalisation algorithms under soft constraint satisfaction
Oguz Tanrikulu, B. Baykal, Anthony George Constantinides, Jonathon A. Chambers · 2002
New constant modulus (CM) algorithms are presented that are based on soft constraint satisfaction. The stationary points of an algorithm in this family are studied for an AR(p) channel and it is shown that Ding-type undesirable local solutions (ULS) do not exist. This is due to the normalisation of the gradient vector and the soft nonlinearity used in these algorithms. Error performance surfaces (EPS) and convergence trajectories from arbitrary initialisations are presented for various channels that support the analytical findings.