A method performed by a network node for determining a mobility criterion related to a wireless communications device in a wireless communications network. The network node obtains an information related to an UL propagation condition associated to the wireless communications device. The network node determines a measure of imbalance between the UL propagation condition and a DL propagation condition associated to the wireless communications device. The measure of imbalance is based on the information related to the UL propagation condition. The network node determines the mobility criterion based on the measure of imbalance between the UL propagation condition and the DL propagation condition.