There is provided a frame structure for a cellular communication system. According to an embodiment, there is provided a first radio frame configuration defining a frame structure of a radio frame comprising at least one sub-frame dedicated only for downlink transmission. There is also provided a second radio frame configuration defining a frame structure of a radio frame comprising at least one flexible special sub-frame configurable as either a flexible downlink sub-frame or as a flexible uplink sub-frame, wherein the flexible downlink sub-frame and the flexible uplink sub-frame both comprise an uplink part and a downlink part, and wherein both the uplink part and the downlink part carry at least one of control information and a reference signal. Amongst a set of radio frame configurations comprising at least the first and second radio frame configuration, a radio frame configuration is selected and a radio signal carrying an information element indicating the selected radio frame configuration is exchanged in order to configure the selected radio frame configuration for use in the cellular communication system.