Which constant modulus criterion is better for blind adaptive filtering: CM(1,2) or CM(2,2)? [equalizer example]

The two most important constant modulus criteria are studied and compared, exploiting recently obtained results. A theoretical analysis of the performance is provided and excess output MSE figures are derived. The answer to the title question is found to depend on the output error power. In applications where the lower bound for the output signal-to-noise ratio is small, typically less than 8 dB, the CM(2,2) criterion can be employed. Otherwise, the CM(1,2) criterion is preferable. This result can be of great help to system designers, to select the constant modulus criterion that best suits their application and their performance objectives.