An operation method of a CP may comprise: requesting a status report from each of terminals and receiving the status report; determining switching from basic transmission mode to cell-free massive MIMO transmission mode for at least part of the terminals based on the status reports; instructing the at least part of the terminals and at least one AN to perform cell-free massive MIMO transmission for the at least part of the terminals to configure cell-free massive MIMO transmission mode; determining analog beam(s) and/or digital precoder(s) to be applied by the at least one AN to the at least part of the terminals based on channel qualities between the at least part of the terminals and the at least one AN; and allowing the at least one AN to perform cell-free massive MIMO transmission to the at least part of the terminals using the analog beam(s) and/or digital precoder(s).