A method (10) performed in a wireless communications system (10) for establishing usefulness of remote units is provided. The wireless communications system (10) monitors one or more remote units (2i, 2j, . . . , 2N) of a distributed antenna system (1). The method (10) comprises: establishing (11), per remote unit (2i, 2j, . . . , 2N), received signal strength of a wireless communication; establishing (12), per remote unit (2i, 2j, . . . , 2N), a quantity related to the obtained received signal strength; and establishing (13) a measure on usefulness of each of two or more remote units (2i, 2j, . . . , 2N) based on the received signal strength and on the quantity. A corresponding wireless communications system, computer programs, and computer program products are also provided.