his step involves selecting which User Equipment (UEs) out of the set of UEs with data available for scheduling will be scheduled. A common approach for UE selection is to define a utility function, a term used in economics to define the level of satisfaction received by a consumer from consumption of a good or a service. A simple utility function is defined by the PF scheduling metric according to the following formula: where R represents the historical average rate, which is calculated as (exponential average filtering) follows: Rit=Ti,t+((Ri,t-1-Ti,t)/Tc) and Ti is the current achievable rate, according to the average signal-to-interference and noise ratio across all subchannels. Tc is the filtering time constant. Note: Eligible UEs are those for which M(i) is highest (arg max(Mi)). Another algorithm that considers both the delay and the QoS is given by the following equation [Modified Largest Weighted Delay First (M-LWDF)): The first factor (log(8)) represents the QoS class, the second factor represents the PF por- tion, and the last factor (Di(t)/Ai) represents the Head of Line Packet Delay/Due Delay, which ranges from 0 to 1 as the packet delay approaches the due delay. 252 Open Radio Access Network (O-RAN) Systems Architecture and Design The following is a generalization/extension of this algorithm: With A, B, C presenting a scheduling factor (e.g., the QoS class, the PF Head of Line Packet Delay, and others), and A, 3, and V weights associated with each fairness factor. A, B, and C can each be a rate averaged metric or other. A PF scheduler implementation that includes active UE filtering is shown in Fig. 7-9. Frequency allocation (frequency-domain scheduling) Frequency-domain scheduling involves the allocation of frequency-domain resources to the time- domain scheduled users (or, more precisely, a subset of the time-domain defined group of eligible users). Goal is to allocate frequency-domain resources to the different users in such a way that the users are using the subset of the frequency domain that p