Method and apparatus for generating training signal using predetermined binary sequence in wireless LAN system
Disclosed are a method and an apparatus for generating an STF signal usable in a wireless LAN system. The STF signal is included in a field used to improve AGC estimation of a MIMO transmission. A portion of the STF signal is used to transmit an uplink, and can be used for uplink MU PPDUs transmitted from a plurality of STAs. The STF signal that is disclosed, for example, is used for a 40 MHz band or an 80 MHz band, is desirably usable for the 40 MHz band, and can be generated based on a sequence in which a predetermined M sequence is repeated. The predetermined M sequence can be a binary sequence of which the length is 15 bits.
1. A method of transmitting a packet in a wireless local area network (LAN) system supporting a first frequency band and a second frequency band, the method performed by a transmitting apparatus and comprising:
selecting a short training field (STF) sequence in which a predetermined M sequence is repeated from a plurality of predetermined sequences;
generating an STF signal corresponding to the first frequency band based on the selected STF sequence; and
transmitting a physical protocol data unit (PPDU) including the generated STF signal to a receiving apparatus,
wherein the selected STF sequence is defined as {M, −1, −M, 0, M, −1, M}*(1+j)/sqrt(2),
wherein sqrt( ) denotes a square root,
wherein the predetermined M sequence corresponds to a binary sequence having a length of 15 bits and is defined as M={−1, −1, −1, 1, 1, 1, −1, 1, 1, 1, −1, 1, 1, −1, 1},
wherein the first frequency band is a 40 MHz band, and
wherein the second frequency band is an 80 MHz band.
2. The method of claim 1 , wherein:
the selected STF sequence is positioned at intervals of 8 tones starting from a lowest tone having a tone index of −248 to a highest tone having a tone index of +248; and
elements corresponding to the −248 and 284 tone indexes are processed as null elements.
3. The method of claim 1 , further comprising:
selecting a first frequency tone interval or a second frequency tone interval; and
configuring the generated STF signal according to the selected first or second frequency tone interval.
4. The method of claim 3 , wherein the first frequency tone is selected if the PPDU is an uplink multi-user PPDU corresponding to a trigger frame received from an access point.
5. The method of claim 3 , wherein:
the first frequency tone interval is; and
the second frequency tone interval is 16.
6. The method of claim 1 , wherein elements in the selected STF sequence are defined in a unit of 78.125 kHz.
7. The method of claim 1 , wherein the STF sequence Hs selected such that automatic gain control estimation is improved when transmitting the PPDU.
8. A transmitting apparatus of a wireless local area network (LAN) system supporting multiple frequency bands including a first frequency band and a second frequency band, the apparatus comprising:
a radio frequency (RF) unit configured to transmit and receive radio signals; and
a processor configured to:
select a short training field (STF) sequence in which a predetermined M sequence is repeated from a plurality of predetermined sequences;
generate an STF signal corresponding to the first frequency band based on the selected STF sequence; and
control the RF unit to transmit a physical protocol data unit (PPDU) including the generated STF signal to a receiving apparatus,
wherein the selected STF sequence is defined as {M, −1, −M, 0, M, −1, M}*(1+j)/sqrt(2),
wherein sqrt( ) denotes a square root,
wherein the predetermined M sequence corresponds to a binary sequence having a length of 15 bits and is defined as M={−1, −1, −1, 1, 1, 1, −1, 1, 1, 1, −1, 1, 1, −1, 1},
wherein the first frequency band is a 40 MHz band, and
wherein the second frequency band is an 80 MHz band.
9. The apparatus of claim 8 , wherein:
the selected STF sequence is positioned at intervals of 8 tones starting from a lowest tone having a tone index of −248 to a highest tone having a tone index of +248; and
elements corresponding to the −248 and 284 tone indexes are processed as null elements.
10. The apparatus of claim 8 , wherein the processor is further configured to:
select a first frequency tone interval or a second frequency tone interval; and
configure the generated STF signal according to the selected first or second frequency tone interval.
11. The apparatus of claim 10 , wherein the first frequency tone is selected if the PPDU is an uplink multi-user PPDU corresponding to a trigger frame received from an access point.
12. The apparatus of claim 10 , wherein:
the first frequency tone interval is; and
the second frequency tone interval is 16.
13. The apparatus of claim 8 , wherein elements in the selected STF sequence are defined in a unit of 78.125 kHz.
14. The apparatus of claim 8 , wherein the STF sequence is selected such that automatic gain control estimation is improved when transmitting the PPDU.