In one non-limiting exemplary embodiment, a method includes: randomly selecting a set of sequences with each sequence having sequence elements, each sequence element having a frequency selected from constellation points on a unit circle in a complex plane, where the selected set of sequences is a candidate set of sequences; calculating a first cubic metric for each sequence of the candidate set of sequences, where the first cubic metric is for single code modulation; and in response to the first cubic metric being larger than at least one threshold, removing the corresponding sequence from the candidate set of sequences to obtain at least one saved sequence.