The application pertains to determining a rank of channel loss extent. A base station sends to a terminal a signaling indicating that there are N ranks of channel loss extent. Each rank has a corresponding number of random access preamble repetitions. The base station receives from the terminal device one or more transmissions of a random access preamble in a first number of repetitions of the random access preamble. The base station determines the rank of channel loss extent according to a random access preamble group in which the received random access preamble is located, or the first number of repetitions of the received random access preamble. A channel loss is a reference signal received power (RSRP). After determining the rank of channel loss extent, the base station determines a second number of repetitions corresponding to the determined rank of channel loss extent, for sending or receiving uplink/downlink information.