Method and apparatus for random access resource selection in mobile wireless communication system

Abstract

A wireless device may receive system information block 1 (SIB1) message of a cell. The SIB1 message may indicate a plurality of configuration parameters comprising a common uplink configuration of an uplink bandwidth part (BWP). The common uplink configuration of the uplink BWP may comprise: a common random access channel (RACH) configuration; a first threshold for determining whether to select a resource associated with a first message 1 (msg1) repetition number, wherein msg1 corresponds to physical random access channel (PRACH) preamble; a second threshold for determining whether to select a resource associated with a second msg1 repetition number; and a second RACH configuration associated with feature combination. The second RACH configuration may comprise a first feature combination preamble parameter that indicates the first msg1 repetition number. The wireless device may determine, based on the first threshold, the first msg1 repetition number, and repeatedly transmit, based on the determined first msg1 repetition number, a PRACH preamble of a random access procedure associated with the first feature combination preamble parameter.