Embodiments are provided to support device-to-device (D2D) communications in a time-division duplexing (TDD) communications system, and ensure that D2D discovery signals are transmitted by user devices on an uplink subframe when there is a TDD frame configuration change. In an embodiment, a user device receives form the network a TDD frame configuration selected from a set of available TDD frame configurations according to the TDD configuration. The device further receives a D2D discovery configuration for a discovery time interval. The user device then allocates a transmission resource a D2D discovery signal within the discovery time interval according to the D2D discovery configuration. The user device is also configured to receive from another device a second D2D discovery signal during the discovery time interval in accordance with the TDD configuration and the D2D discovery configuration.