An IAB node performs a method for determining a periodicity of a SSB and/or a RMSI for use in an IAB backhaul link. The method may comprise one or more of: using a predetermined periodicity value; determining a periodicity value based on at least one different parameter; receiving a signaling message indicating a periodicity value and using the indicated periodicity value for the IAB backhaul link; and selecting a periodicity value from a plurality of permitted periodicity values.