We consider a user-centric scalable cell-free massive MIMO network with a
total of LM distributed remote radio unit antennas serving K user
equipments (UEs). Many works in the current literature assume LM≫K,
enabling high UE data rates but also leading to a system not operating at its
maximum performance in terms of sum throughput. We provide a new perspective on
cell-free massive MIMO networks, investigating rate allocation and the UE
density regime in which the network makes use of its full capability. The UE
density K approximately equal to 2LM is the range in which the
system reaches the largest sum throughput. In addition, there is a significant
fraction of UEs with relatively low throughput, when serving K>2LM
UEs simultaneously. We propose to reduce the number of active UEs per time
slot, such that the system does not operate at ``full load'', and impose
throughput fairness among all users via a scheduler designed to maximize a
suitably defined concave componentwise non-decreasing network utility function.
Our numerical simulations show that we can tune the system such that a desired
distribution of the UE throughput, depending on the utility function, is
achieved