In case the UE selects multiple RAP TX Beams, the UE may transmit different RAPs on different RAP TX Beams or the UE may repeat transmitting the same RAP on different RAP TX Beams.

FIG. 10 shows another example of random access procedure of one embodiment of the present invention.

As like in FIG. 9, each beam is associated with a specific RACH resource. For example, Beam1, Beam2, Beam3, Beam4, and Beam5 are associated with RACH resource on subframe5/10/ . . . , subframe1/6/11/ . . . , subframe2/7/12 . . . , subframe3/8/ . . . , and subframe4/9/ . . . , respectively.

The beam quality is decreasing in order of Beam2, Beam3, Beam1, Beam4, and Beam5. I.e., Beam2 has the best beam quality while Beam5 has the worst beam quality from the UE perspective. Thus, the UE considers that Beam2 is a serving beam. Among 5 beams, the UE is to consider 3 beams as candidate beams in decreasing order of beam quality, i.e., the UE determines that Beam1, Beam2, and Beam3 are candidate beams.

In FIG. 10, the UE triggers a RA procedure on subframe2 (S1010), and the UE is able to transmit a RAP from subframe8 due to 6 ms of processing time (S1020).

In this case, the UE can select Beam1 as RAP TX beam because Beam1 can be used for transmitting a RAP at the earliest point in time domain among the candidate beams, i.e., subframe10. So, the UE transmits a RAP on subframe10 by using Beam1.

Apparatus for Candidate Beams Based Random Access