For an example embodiment, a method for a communication device operating in a synchronous communication system is described. The method includes performing a listen-before-talk (LBT) procedure prior to the start of a downlink subframe of a synchronous frame and determining if a transmission from another communication device of another communication system is detected during the LBT procedure. In the case that a transmission is detected during the LBT procedure, the communication device refrains from transmitting during the downlink subframe. In the case that a transmission is not detected during the LBT procedure, the communication device transmits during the downlink subframe.