A unified frame structure is scalable to meet the 5G new radio requirements, to support flexible TDD configurations, to support multiple numerologies, and to adapt to the channel properties of different spectrums up to 100 GHz. Multiple numerologies with 15 KHz subcarrier spacing and its integer or 2m multiple are proposed, where m is a positive integer. Under the unified frame structure, each radio frame is a basic operation time unit in higher layer and comprises a plurality of slots, and each slot within a radio frame is a basic scheduling time unit in physical layer and comprises a predefined number of OFDM symbols. A semi-static configuration configures DL-only slot type via system information or higher-layer signaling, while a physical layer signaling is used to dynamically configure flexible slot types.