The present disclosure relates to a communication method and system for converging a 5th-Generation (5G) communication system for supporting higher data rates beyond a 4th-Generation (4G) system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. A downlink transmission method performed by user equipment and user equipment are provided. The downlink transmission method performed by the user equipment includes: receiving a predefined downlink signal in a predefined downlink resource, and performing ACK feedback according to the received downlink signal, thereby implementing the performing of downlink data transmission in an RRC idling or inactive state, or establishing RRC connection more rapidly.