A method performed by a network node for allocating reference signals to a set of sector carriers provided by the network node for a communication with a UE in a radio network is provided. The network node allocates reference signals to each respective sector carrier, by for each respective sector carrier, allocating a reference signal to the sector carrier, and a parameter representing the sector carrier. The network node transmits the reference signal in each respective sector carrier and evaluates a neighboring relationship between the sector carriers, to identify if two neighboring sector carriers within the one or more cells are allocated the same reference signal. When identified that two neighboring sector carriers are allocated the same reference signal within one or more cells comprising the sector carriers, the network node re-allocates at least one of the two neighboring sector carriers with another available reference signal.