Provided is a base station. The base station includes a transceiver, a frequency allocation unit, and an orthogonal code allocation unit. The transceiver communicates with a terminal. The frequency allocation unit allocates a frequency resource to the terminal through the transceiver. The orthogonal code allocation unit generates an orthogonal code index table including a plurality of orthogonal code combinations, and allocates one of the orthogonal code combinations included in the orthogonal code index table to each terminal, to which the frequency resource has been allocated for a service request of the terminal, through the transceiver not to multiply be allocated. At least one of a plurality of orthogonal codes included in the orthogonal code combination is orthogonal to at least one of a plurality of orthogonal codes included in an orthogonal code combination allocated to another terminal.