  Cell-free massive MIMO (CF-mMIMO) represent a deeply investigated evolution
from the conventional multicell co-located massive MIMO (MC-mMIMO) network
deployments. Anticipating a gradual integration of CF-mMIMO systems alongside
pre-existing MC-mMIMO network elements, this paper considers a scenario where
both deployments coexist, in order to serve a large number of users using a
shared set of frequencies. The investigation explores the impact of this
coexistence on the network's downlink performance, considering various degrees
of mutual cooperation, precoder selection, and power control strategies.
Moreover, to take into account the effect of the proposed cooperation scenarios
on the fronthaul links, this paper also provides a fronthaul-aware heuristic
association algorithm between users and network elements, which permits
fulfilling the fronthaul requirement on each link. The research is finally
completed by extensive simulations, shedding light on the performance outcomes
associated with the diverse cooperation levels and several solutions delineated
in the paper.
