A method for cellular network operation includes establishing communications in a cellular network between a given user equipment (UE) and a base station, comprising a virtualization platform and radio transceiver points (R-TP). A central coordinator selects a downlink coordinated transmission mode involving a first and a second R-TP which receive messages, over a control interface between the virtualization platform and each R-TP, including specifications of time-frequency resources to be used for user data and reference signals transmission. The radio processing functions in the communications with the given UE are performed while executing the selected coordinated mode by both selected R-TPs in accordance with the time-frequency resource specifications.