In this paper, we investigate the impact of multiple-antenna
deployment at access points (APs) and users on the performance
of cell-free massive multiple-input multiple-output
(MIMO). The transmission is done via time-division duplex
(TDD) protocol. With this protocol, the channels are first
estimated at each AP based on the received pilot signals
in the training phase. Then these channel information will
be used to decode the symbols before sending to all users.
The simple and distributed conjugate beamforming technique
is deployed. We derive a closed-form expression for the
downlink spectral efficiency taking into account the imperfect
channel state information (CSI), non-orthogonal pilots,
and power control. This spectral efficiency can be achieved
without the knowledge of instantaneous CSI at the users. In
addition, the effects of the number antennas per APs and per
users are analyzed in the case of using mutual orthogonal
pilot sequences and data power control.