Method and apparatus for generating training signal by using binary sequence in wireless LAN system
Disclosed are a method and apparatus for generating a short training field (STF) sequence that can be used in a wireless LAN system. The STF signal is included in a field used to improve AGC estimation of MIMO transmission. Some of the STF signals may be used for uplink transmission and may be used for uplink MU PPDU transmitted from a plurality of STAs. For example, the STF signal is used for an 80 MHz band or a 160 MHz band and may be generated based on a sequence having a preset repeated M sequence. The preset M sequence may represent a binary sequence of a length having 15 bits.
1. A method in a wireless LAN system for supporting a plurality of frequency bands including a first frequency band and a second frequency band, the method comprising:
generating a Short Training Field (STF) related to the first frequency band by a transmitting apparatus; and
transmitting an STF sequence related to the first frequency band to a receiver by the transmitting apparatus,
wherein a guard tone and a DC tone of a sequence located at the second frequency band in the STF sequence related to the first frequency band,
when the second frequency band is located at a first sub-band of the first frequency band, the STF sequence related to the second frequency band is defined based on a preset M sequence as {M, 1, −M, 0, −M, 1, −M}*(1+j)/sqrt(2), where sqrt( ) represents a square root, and the preset M sequence represents a binary sequence of a length having 15 bits and is defined as M={−1, −1, −1, 1, 1, 1, −1, 1, 1, 1, −1, 1, 1, −1, 1}.
2. The method of claim 1 , wherein an STF sequence related to the first frequency band is disposed at 16 tone intervals from a lowest tone having a tone index −496 to a highest tone having a tone index +496.
3. The method of claim 1 , wherein a tone having a tone index −384 in an STF sequence related to the first frequency band is set as null.
4. The method of claim 1 , wherein when the second frequency band is located at a second sub-band of the first frequency band, an STF sequence related to the first frequency band is defined as {M, 0, −M, 0, −M, 1, −M}*(1+j)/sqrt(2) based on a preset M sequence, and
a tone having a tone index −128 in an STF sequence related to the first frequency band is set as null.
5. The method of claim 1 , wherein when the second frequency band is located at a third sub-band of the first frequency band, an STF sequence related to the first frequency band is defined as {M, 1, −M, 0, −M, 1, −M}*(1+j)/sqrt(2) based on a preset M sequence, and
a tone having a tone index 128 in an STF sequence related to the first frequency band is set as null.
6. The method of claim 1 , wherein when the second frequency band is located at a fourth sub-band of the first frequency band, an STF sequence related to the first frequency band is defined as {M, 1, −M, 0, −M, 0, −M}*(1+j)/sqrt(2) based on a preset M sequence, and,
a tone having a tone index 384 in an STF sequence related to the first frequency band is set as null.
7. The method of claim 1 , wherein the first frequency band comprises a 80 MHz band, and the second frequency band comprises a 20 MHz band, and
a first sub-band of the first frequency band comprises the 20 MHz band.
8. The method of claim 1 , wherein an STF sequence related to the first frequency band is used to improve automatic gain control (AGC) estimation in multiple input multiple output (MIMO) transmission.
9. A transmitting apparatus in a wireless LAN system, the transmitting apparatus comprising:
a transceiver; and
a processor configured to control the transceiver,
wherein the processor generates a Short Training Field (STF) related to the first frequency band by a transmitting apparatus; and
transmits an STF sequence related to the first frequency band to a receiver by the transmitting apparatus,
wherein a guard tone and a DC tone of a sequence located at the second frequency band in the STF sequence related to the first frequency band,
when the second frequency band is located at a first sub-band of the first frequency band, the STF sequence related to the second frequency band is defined based on a preset M sequence as {M, 1, −M, 0, −M, 1, −M}*(1+j)/sqrt(2), where sqrt( ) represents a square root, and
the preset M sequence represents a binary sequence of a length having 15 bits and is defined as M={−1, −1, −1, 1, 1, 1, −1, 1, 1, 1, −1, 1, 1, −1, 1}.