ws: Multicarrier NOMA can be viewed as a variation of NOMA, where the users in a network are divided into multiple groups. The users in each group are served in the same orthogonal resource block following the NOMA principle, and different groups are allocated to New Radio Access Physical Layer Aspects (Part 1) 365 different orthogonal resource blocks. The motivation for employing hybrid NOMA is to reduce the system complexity. For example, assigning all the users in the network to a sin- gle group for the implementation of NOMA in one orthogonal resource block is problem- atic, since the user having the best channel conditions will have to decode all the other users' messages before decoding its own message, which results in high-complexity and high-decoding delay. Hybrid NOMA is an effective approach to make a tradeoff between system performance and complexity. Let's consider multicarrier NOMA as an example. The users in the cell are divided into multiple groups which are not necessarily mutually exclu- sive. The users within one group are assigned to the same subcarrier, and intra-group interference is mitigated using the NOMA principle. Different groups of users are assigned to different subcarriers, which effectively avoids inter-group interference. As a result, overloading the system, which is necessary in order to support more users than the number of available subcarriers and is required to enable massive connectivity, can be realized by the hybrid NOMA scheme. It is noted that, with hybrid NOMA, overloading is realized at reduced complexity since the number of users assigned to each subcarrier is limited [50-52]. The base station scheduler in power-domain NOMA searches and pairs multiple users for simultaneous transmission at each subband. To determine the set of paired users and the allocated power set at each subband, a multi-user proportional fairness (PF) scheduler may be used. The PF scheduling metric attempts to find the candidate user sets U and power sets Ps that maximize the following expression