1. An operation method of a base station in a communication system, comprising:transmitting, to a terminal, first downlink control information (DCI) including a system information-radio network temporary identifier (SI-RNTI) through a first physical downlink control channel (PDCCH);
transmitting, to the terminal, system information (SI) which includes information indicating a format of second DCI for a random access procedure and sequence information of a random access preamble through a physical downlink shared channel (PDSCH) configured by the SI-RNTI;
transmitting, to the terminal, the second DCI, indicated by the SI, which includes resource information of a physical random access channel (PRACH) in which the random access preamble is transmitted, a transmission period of the random access preamble, and a transmission number of the random access preamble through a second PDCCH; and
receiving, from the terminal, the random access preamble based on the SI and the second DCI.