Patent ID: 8477799

Claim:
A BS (base station) of an OFDMA (orthogonal frequency division multiple access)-based cognitive radio system comprising: a band allocator allocating a channel band of unused channel bands having a bandwidth that is a natural number times a bandwidth resolution to a CPE (customer premises equipment) of a secondary user, the unused channel bands being channel bands among a range of frequencies allowed to but not used by a primary user, wherein the bandwidth resolution is a predetermined bandwidth smaller than a bandwidth of a broadcast channel band; and a transmitter transmitting an OFDMA-based signal comprising a preamble sequence that comprises band allocation information indicating information regarding the allocated channel band, wherein the band allocation information comprises at least one of fractional bandwidth mode information and channel bonding information, wherein the band allocator allocates a fraction of the broadcast channel band as a channel band for the CPE according to fractional bandwidth mode information, or allocates a channel band formed by bonding together a bundle of broadcast channel bands as the channel band for the CPE according to the channel bonding information, or allocates a plurality of fractions of broadcast channel bands as the channel band for the CPE according to the channel bonding information.