Disclosed are a communication method for merging, with IoT technology, a 5G communication system for supporting a data transmission rate higher than that of a 4G system, and a system therefor. The disclosure can be applied to intelligent services (for example, smart home, smart building, smart city, smart car or connected car, healthcare, digital education, retail, security and safety-related services, and the like) on the basis of a 5G communication technology and IoT-related technology. In addition, disclosed in the specification are: an adaptive retransmission method and device for delay reduction; a method and a device for selecting radio resource allocation and data size; and a method and a device for performing setting so as to enable different channels to share DMRS with each other.