Base station

A base station of a radio communication system including the base station and one or more mobile stations that communicate with the base station, the base station comprising:

• a receiver that receives, from each of the one or more mobile stations, a signal of a specific random access sequence of a plurality of random access sequences;
• and
• an identifier that identifies the specific random access sequence of the plurality of random access sequences and a receiving direction in which the signal of the specific random access sequence is received, based on absolute values of a plurality of total values, each of the plurality of total values being obtained by calculating correlation values for combinations between signals in a respective plurality of reception directions to which weights corresponding to the plurality of reception directions are applied and the plurality of random access sequences, and by adding the correlation values for the combinations corresponding to one random access sequence of the plurality of random access sequences.