According to  from our publication, Hanning filter has better performance than Hamming and Chebyshev flter (Figure 3).
So, in the simulator we use Hanning due to the best side lobe attenuation.
Of course, you can easily implement any of these filters within UFMC.
In the current implementation it is not possible to dynamically allocate different size of subbands within one user.
If you want to change the number of subcarriers per subband, you can manually predefined obj.Nr.Subbands and the scStr.modulation.nSubcarriersPerSubband within each subband. In that situation you have to be aware of the subband filtering, and check whether it is enough accurate or not (for further information about this see Nokia’s proposal about UFMC).
If you have two or more users, you can use different size of subcarriers per subband, simply adding the desired number in scStr.modulation.nSubcarriersPerSubband = [12, 6];, meaning that for the first user you have 12 subcarriers per subband, while for the second 6 subcarriers per subband.