  A novel generalized coordinated multi-point transmission (GCoMP)-enabled
non-orthogonal multiple access (NOMA) scheme is proposed. In particular, the
traditional joint transmission CoMP scheme is generalized to be applied for all
user-equipments (UEs), i.e. both cell-centre and cell-edge users within the
coverage area of cellular base stations (BSs). Furthermore, every BS applies
NOMA for all UEs associated to it using the same frequency sub-band (i.e. all
UEs associated to a BS forms a single NOMA cluster). To evaluate the proposed
scheme, we derive a closed-form expression for the probability of outage for a
UE with different orders of BS cooperation. Important insights on the proposed
system are extracted by deriving an approximate (asymptotic) expressions for
the probability of outage and outage capacity. Furthermore, an optimal
transmission power allocation scheme that jointly allocates transmission power
fractions from all cooperating BSs to all connected UEs is developed and
investigated for the proposed system. Findings show that NOMA with a large
number of UEs is feasible when the GCoMP technique is used over all UEs within
the network coverage area. Also, the performance degradation caused by a large
NOMA cluster size is significantly mitigated by increasing the number of
cooperating BSs. In addition, for given feasible system parameters and a given
NOMA cluster, the lower the available power budget, the higher is the number of
BSs that apply NOMA for their cluster members and the lower the number of BSs
that use water-filling for power allocation.
