Patent ID: 8295266

Claim:
A method for setting RACH (Random Access Channel) transmission of a user equipment (UE) to prepare for a frequency offset, the method comprising: setting a first RACH setup condition for a highspeed UE and a second RACH setup condition for a low-speed UE; and transmitting information about at least the first RACH setup condition or the second RACH setup condition via a downlink, wherein the first RACH setup condition and the second RACH setup condition include at least a first condition for RACH structures for use in each of the high-speed UE and the low-speed UE, a second condition for preamble structures applied to each of the high-speed UE and the low-speed UE in the same RACH structure, or a third condition for sequence sets for each of the high-speed UE and the low-speed UE, and wherein the condition for sequence sets for each of the high-speed UE and the low-speed UE is set to a set of CAZAC sequences and the sequence set for the high-speed UE is set to a Zero Correlation Zone (ZCZ) sequence set in which a CAZAC index is within an initial predetermined range or within a last predetermined range if the third condition is set.