Techniques are provided to ensure that a terminal device is able to perform measurements efficiently when an on/off scheme is used by network nodes, particularly in a heterogeneous network environment. An example method, implemented in a network node, comprises obtaining a discovery signal window pattern, the discovery signal window pattern defining one or more discovery signal windows during which each of a plurality of cells is to transmit a corresponding discovery signal, and sending an indication of the discovery signal window pattern to a terminal device.