# US 10,320,590 B2 · Method and apparatus for generating STF signal using binary sequence in wireless LAN system

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- Number: US 10,320,590 B2
- Document ID: US10320590B2
- Status: Granted
- Kind: B2
- Application number: 15/516,346
- Filed: 2016-08-05
- Published: 2017-10-26
- Granted: 2019-06-11
- Earliest claimed: 2015-08-06
- Assignees: LG Electronics Inc.
- Applicants: LG Electronics Inc.
- Inventors: Eunsung Park; Jinsoo Choi; Hangyu Cho
- Web page: https://patentgrep.com/patent/US10320590B2

## CPC

- H04L 1/0031: {Multiple signaling transmission (H04L1/1664, F15 take precedence)}
- H04L 1/001: {applied to control information}
- H04L 5/0048: {Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091)}
- H04L 25/03: Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L 27/2613: {Structure of the reference signals}
- H04L 27/34: Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
- H04W 84/12: WLAN [Wireless Local Area Networks]
- H04L 5/0007: {the frequencies being orthogonal, e.g. OFDM(A) or DMT}
- H04L 5/0037: {Inter-user or inter-terminal allocation}
- H04L 27/26132: {using repetition}
- H04L 27/2666: {Acquisition of further OFDM parameters, e.g. bandwidth, subcarrier spacing, or guard interval length}
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

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.

## Claims

### Claim 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}.

### Claim 2 (depends on 1)

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.

### Claim 3 (depends on 1)

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.

### Claim 4 (depends on 3)

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.

### Claim 5 (depends on 3)

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.

### Claim 6 (depends on 1)

The method of claim 1, wherein the transmission frequency band is an 80 MHz band.

### Claim 7 (depends on 1)

The method of claim 1, wherein elements in the STF sequence are defined in a unit of 78.125 kHz.

### Claim 8 (depends on 1)

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.

### Claim 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}.

### Claim 10 (depends on 9)

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.

### Claim 11 (depends on 9)

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.

### Claim 12 (depends on 11)

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.

### Claim 13 (depends on 11)

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.

### Claim 14 (depends on 9)

The transmitting apparatus of claim 9, wherein the transmission frequency band is an 80 MHz band.

### Claim 15 (depends on 9)

The transmitting apparatus of claim 9, wherein elements in the STF sequence are defined in a unit of 78.125 kHz.

### Claim 16 (depends on 9)

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.