If you are using the hLoadConfiguration helper function, you can use the following line afterwards:
nodeConfigs(nodeIdx).BandAndChannel = {[Band1, Channel1] [Band2, Channel2] [Bandn, Channeln]};
where nodeIdx is the node identifier and each interface is defined by a [Band, Channel] vector. You can select the bands and channels according to your needs.
You can also modify the BandAndCHannel field in the wlanNodeConfig.mat file to turn it into a 1xn cell array, where each cell contains the corresponding [Band, Channel] vector.
