A base station that monitors one or more channel conditions of an unlicensed carrier to detect whether there is an interfering signal in the unlicensed carrier. The base station may detect an interfering signal that, for instance, is hidden from and difficult to detect by a WCD that has UL data to send. If the base station detects an interfering signal on the unlicensed carrier, it proceeds with transmitting a UL grant message to the WCD, however, the base station may configure the transmission of the UL grant message to the WCD based on the interfering signal. For instance, the base station may determine, based on the interfering signal, when to transmit the UL grant message, or may determine, based on the interfering signal, UL transmission parameter values to include in the UL grant message, or any combination thereof.