There is provided a method and a network node for allocating and transmitting Mobility Reference Signals, MRS, for a communication device to measure beam signal quality in a wireless communication network. The network node obtains information on one or more of a frequency diversity, a time diversity of a channel between the network node and the communication device, an antenna spatial diversity of the communication device. The network node selects an MRS pattern out of a set of candidate patterns based on the received information, signals the selected MRS pattern to the communication device and transmits the MRS according to the selected MRS pattern.