Method and apparatus for generating STF signal using 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 that is suggested, for example, is used for a 40 MHz band or an 80 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 in a wireless local area network (LAN) system, the method comprising:
selecting, by a transmitting apparatus, a short training field (STF) sequence from a plurality of predetermined sequences, wherein the selected STF sequence includes a predetermined M sequence;
generating, by the transmitting apparatus, an STF signal used for a transmission frequency band based on the selected STF sequence; and
transmitting, by the transmitting apparatus, a physical protocol data unit (PPDU) including the generated STF signal to a receiving apparatus,
wherein the selected STF sequence is defined as shown below:
{M, −1, M, −1, −M, −1, M, 0, −M, 1, M, 1, −M, 1, −M}*(1+j)/sqrt(2), wherein sqrt( ) denotes a square root, and
wherein the predetermined M sequence is a sequence having a length of 15 bits and is defined as shown below:
M={−1, −1, −1, 1, 1, 1, −1, 1, 1, 1, −1, 1, 1, −1, 1}.
2. The method of claim 1 ,
wherein the {M, −1, M, −1, −M, −1, M, 0, −M, 1, M, 1, −M, 1, −M}*(1+j)/sqrt(2) sequence is positioned at intervals of 8 tones starting from a lowest tone having a tone index of −504 and up to a highest tone having a tone index of +504, and
wherein, elements corresponding to tone indexes −504 and 504 in the {M, −1, M, −1, −M, −1, M, 0, −M, 1, M, 1, −M, 1, −M}*(1+j)/sqrt(2) sequence are processed to be null elements.
3. The method of claim 1 , wherein the transmitting apparatus selects a first frequency tone interval or a second frequency tone interval, and wherein the transmitting apparatus generates the STF signal based on the selected frequency tone interval.
4. The method of claim 3 , wherein, in case the PPDU is an uplink MU PPDU corresponding to a trigger frame received from an access point (AP), the first frequency tone is selected.
5. The method of claim 3 , wherein the first frequency tone interval is equal to 8, and wherein the second frequency tone interval is equal to 16.
6. The method of claim 1 , wherein the transmission frequency band is an 80 MHz band.
7. The method of claim 1 , wherein elements in the STF sequence are defined in a unit of 78.125 kHz.
8. The method of claim 1 , wherein the STF sequence is selected by the transmitting apparatus from the plurality of predetermined sequences to improve automatic gain control (AGC) estimation in transmission from the transmitting apparatus.
9. A transmitting apparatus of a wireless local area network (LAN) system, comprising:
a radio frequency (RF) unit transmitting or receiving radio signals; and
a processor controlling the RF unit,
wherein the processor is configured:
to select a short training field (STF) sequence from a plurality of predetermined sequences, wherein the selected STF sequence includes a predetermined M sequence;
to generate an STF signal used for a transmission frequency band based on the selected STF sequence; and
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 shown below:
{M, −1, M, −1, −M, −1, M, 0, −M, 1, M, 1, −M, 1, −M}*(1+j)/sqrt(2), wherein sqrt( ) denotes a square root, and
wherein the predetermined M sequence is a sequence having a length of 15 bits and is defined as shown below:
M={−1, −1, −1, 1, 1, 1, −1, 1, 1, 1, −1, 1, 1, −1, 1}.
10. The transmitting apparatus of claim 9 ,
wherein the {M, −1, M, −1, −M, −1, M, 0, −M, 1, M, 1, −M, 1, −M}*(1+j)/sqrt(2) sequence is positioned at intervals of 8 tones starting from a lowest tone having a tone index of −504 and up to a highest tone having a tone index of +504, and
wherein, elements corresponding to tone indexes −504 and 504 in the {M, −1, M, −1, −M, −1, M, 0, −M, 1, M, 1, −M, 1, −M}*(1+j)/sqrt(2) sequence are processed to be null elements.
11. The transmitting apparatus of claim 9 , wherein the transmitting apparatus selects a first frequency tone interval or a second frequency tone interval, and wherein the transmitting apparatus generates the STF signal based on the selected frequency tone interval.
12. The transmitting apparatus of claim 11 , wherein, in case the PPDU is an uplink multi user (MU) PPDU corresponding to a trigger frame received from an access point (AP), the first frequency tone is selected.
13. The transmitting apparatus of claim 11 , wherein the first frequency tone interval is equal to 8, and wherein the second frequency tone interval is equal to 16.
14. The transmitting apparatus of claim 9 , wherein the transmission frequency band is an 80 MHz band.
15. The transmitting apparatus of claim 9 , wherein elements in the STF sequence are defined in a unit of 78.125 kHz.
16. The transmitting apparatus of claim 9 , wherein the STF sequence is selected by the transmitting apparatus from the plurality of predetermined sequences to improve automatic gain control (AGC) estimation in transmission from the transmitting apparatus.