The present invention relates to a method for generating a downlink frame includes: generating a first short sequence and a second short sequence indicating cell group information; generating a first scrambling sequence determined by a first synchronization signal; generating a second scrambling sequence determined by a group to which the first short sequence belongs, the wireless communication system using a plurality of short sequences and the plurality of short sequence being divided into a plurality of groups; scrambling the first short sequence with the first scrambling sequence; scrambling the second short sequence with at least the second scrambling sequence; and mapping a second synchronization signal including the scrambled first short sequence and the scrambled second short sequence in the frequency domain.