Network node and UE, and methods therein for signaling system information, SI, to UEs. The method in the network node comprises transmitting SI to one or more UEs, where the SI comprises multiple alternative sets, where each set assigns different values to one or multiple radio system parameters. The method further comprises determining which set, out of the multiple alternative sets, that should currently be applied for a UE, and transmitting an SI selection signal to the UE, the SI selection signal indicating the determined set,thus enabling the UE to apply currently appropriate radio system parameters also in unfavorable radio conditions. The UE may be an MTC device (Machine Type Communication).