As shown in FIG. 7, in the second exemplary embodiment of the present invention, an association between an SS burst set and RA preamble resources of a PRACH resource set according to beam grouping is defined. The SS burst set includes a plurality of SS bursts, and each SS burst includes SS blocks that are located consecutively. The PRACH resource includes a plurality of PRACH resources, and each PRACH resource may have a structure as shown in (a) of FIG. 4. Each SS burst corresponds to a PRACH resource. SS blocks of a SS burst correspond to different RA preamble resources of a PRACH resource.

The method according to the first exemplary embodiment of the present invention as noted above may be applied to the second exemplary embodiment of the present invention.

FIG. 8 shows a flowchart of a method for random access according to a second exemplary embodiment of the present invention.

As shown in FIG. 8, a base station 1 transmits SS blocks through a plurality of downlink (DL) Tx beams (S200), a terminal 2 first detects the SS blocks during an initial access (S210). The SS block carries DL beam index information of a base station. Here, the DL beam index information may include a beam group index corresponding to a group index for a PRACH resource and a beam index corresponding to an RA preamble resource index of a PRACH resource according to beam grouping.