In General, Orthogonal Multiple Access technology are much useful to avoid interference(Intra-cell/interuser). For Example, In a case of two users, if channel gains are equal/symmetric, both the users can achieve the sum rate capacity equally(and will produce linear range). However, for Channel having Asymmetric gains leads to more capacity achievement when used in terms of NOMA concept(i.e power inversely proportional to channel gains).
One code is attached here.
Case: Channel is asymmetric for both the users and NOMA produces more sum rate capacity in the middle range compared to OMA.