A method of selecting signatures for a random access in a wireless communication system is presented. The method includes receiving information comprising at least one root sequence index, a cyclic shift parameter, and a configuration parameter that corresponds to different power metric threshold values, providing at least one root sequence table for random access transmission according to the configuration parameter, and accessing the at least one root sequence table is accessed to generate a predetermined number of signatures for accessing the base station, the at least one root sequence table accessed according to the at least one root sequence index and the cyclic shift parameters, wherein the root sequence table comprises a plurality of root sequences arranged in first and second root sequence groups.