The present invention relates to a method and apparatus for function testing of a base station system in a wireless communication system, wherein the base station system comprises at least two antennas and at least two transceivers, and said antennas are intended to cover a target area. Function testing of the parts in the base station is based on measurements of performance variations caused by for example bad contact in feeders, misdirected or malfunctioning antennas, malfunctioning feeders, wear and tear of transceivers, and/or corrosion in feeder connections etc. By alternating between TRXs in the base station system for carrying BCCH messages the performance of each TRX is measured at each time period and stored for further analysis. Thereby a decrease or a fault in the base station system is easily detected.