Method and apparatus for configuring a long training field in a wireless local area network system

A transmitting apparatus for configuring a Long Training Field (LTF) in a wireless LAN system, comprising:

• a radio frequency unit (RF unit) configured to transmit or receive radio signals;
• and
• a processor configured to control the RF unit,
• wherein the processor:
• configures a LTF for a second frequency band of a second wireless LAN system by using a LTF sequence for a first frequency band of a first wireless LAN system, and
• transmits the LTF for the second frequency band through a Physical layer Protocol Data Unit (PPDU) including a first field area and a second field area,
• wherein the second field area includes the LTF and a data field for the second frequency band,
• wherein an Inverse Discrete Fourier Transform (IDFT)/Discrete Fourier Transform (DFT) period being applied to each symbol of the first field area is shorter than an IDFT/DFT period being applied to each symbol of the second field area, and
• wherein a bandwidth of the first frequency band is larger than a bandwidth of the second frequency band.