A wireless communication system (100) is disclosed in which UEs (120a-120c) can operate in a cellular mode wherein data is transmitted from one UE to another via one or more access nodes in a cellular network, and at least some UEs (120c) are D2D-UEs which can also operate in a direct communication mode wherein a pair of D2D-UEs transmit data directly from one to the other, wherein D2D-UEs operating in the direct communication mode maintain control signaling connection with the network and periodically change to the cellular mode and send CSI to the network, and the network uses CSI and/or network available geographical location information for D2D-UEs in determining whether to cause D2D-UEs to operate in the direct communication mode or the cellular mode.