Patent ID: 7787519

Claim:
A preamble transmission method according to which, in an uplink transmission from each of a plurality of mobile stations to a base station, to which a direct sequence code division multiple access system that employs a plurality of carriers, is applied, the mobile stations transmit a preamble to the base station before transmitting an information symbol sequence, comprising: a first carrier selection step in which the mobile stations select at least two carriers from among the plurality of carriers; a transmission control step in which the preamble is repeatedly transmitted by the at least two selected carriers from each mobile station until a preamble receipt confirmation signal is received at each of the mobile station from the base stations for the associated transmitted preamble with a predetermined maximum number of preamble transmissions serving as an upper limit number as to each selected preamble transmission; a power control step in which the mobile stations repeatedly vary the transmission power used for the repeated transmissions of the preamble of each selected carrier on the basis of at least one of total transmitted packet volume and transmitted packet volume by each carrier reported by the base station, a priority level and information volume of the transmitted information symbol sequence, and the number of carriers transmitting a preamble; a second carrier selection step in which the mobile stations further select a symbol sequence carrier for transmitting the information symbol sequence from among each of the plurality of carriers for which the preamble receipt confirmation signal has been received from the base station; and an information symbol sequence transmission step in which the mobile stations transmit the information symbol sequence by the selected symbol sequence carrier.