Method for allocating frequency resources in wireless communication system, and apparatus using the same

A wireless device for allocating frequency resources in a wireless communication system having a first orthogonal frequency division multiplexing (OFDM) system and a second OFDM system multiplexed in a frequency domain, the wireless device comprising:

• a transceiver configured to transmit and receive radio signals;
• and
• a processor operatively connected to the transceiver,
• wherein the processor is configured to:
• determine frequency resource sizes of the first OFDM system and the second OFDM system,
• wherein the first OFDM system includes an inverse discrete Fourier transform (IDFT) block and a Cyclic Prefix (CP) inserting unit being connected to the IDFT block, and
• wherein the second OFDM system includes an IDFT block performing IDFT in frequency resource block units and a filter filtering output signals of the IDFT block in frequency resource block units,
• to allocate frequency resources of the first OFDM system and the second OFDM system based on the determined frequency resource sizes,
• wherein a guard subcarrier is allocated to an adjacent subcarrier where the frequency resources of the first and second OFDM systems are adjacent, and
• wherein control data and user data are not transmitted in the guard subcarrier, and
• transmit information on the frequency resources to a receiver,
• information indicating allocation of any one of the guard subcarrier and the null data wherein, in case a Cell-specific Reference Signal (CRS) is not positioned in the adjacent subcarrier, the guard subcarrier is allocated to the adjacent subcarrier, and
• wherein, in case a CRS is positioned in the adjacent subcarrier, the guard subcarrier is allocated to a subcarrier that is shifted as much as one subcarrier from the adjacent subcarrier.