# US 2018/0324840 A1 · Method for transmitting and receiving uplink acknowledgement signal in wireless lan system and apparatus therefor

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- Number: US 2018/0324840 A1
- Document ID: US20180324840A1
- Status: Published application
- Kind: A1
- Application number: 15/772,799
- Filed: 2017-01-16
- Published: 2018-11-08
- Earliest claimed: 2016-02-17
- Assignees: LG Electronics Inc.
- Applicants: LG Electronics Inc.
- Inventors: Jeongki KIM; Kiseon RYU; Hangyu CHO
- Web page: https://patentgrep.com/patent/US20180324840A1

## CPC

- H04L 27/2602: {Signal structure}
- H04L 1/00: Arrangements for detecting or preventing errors in the information received {(correcting synchronisation H04L7/00)}
- H04L 1/0025: {Transmission of mode-switching indication}
- H04L 1/16: in which the return channel carries supervisory signals, e.g. repetition request signals
- H04L 1/1614: {using bitmaps}
- H04L 1/1861: {Physical mapping arrangements (for ACK signaling see also H04L5/0053)}
- H04L 1/1896: {ARQ related signaling}
- H04L 5/0055: {Physical resource allocation for ACK/NACK (for physical mapping arrangements in ARQ protocols H04L1/1861)}
- H04L 5/0092: {Indication of how the channel is divided}
- H04L 27/26: Systems using multi-frequency codes (H04L27/32 takes precedence)
- H04L 27/2646: {using feedback from receiver for adjusting OFDM transmission parameters, e.g. transmission timing or guard interval length}
- H04W 72/23: in the downlink direction of a wireless link, i.e. towards a terminal
- H04W 84/12: WLAN [Wireless Local Area Networks]
- H04B 7/0452: Multi-user MIMO systems
- H04L 1/0003: {by switching between different modulation schemes}
- H04L 2001/125: {Arrangements for preventing errors in the return channel}
- 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)
- H04B: TRANSMISSION

## Abstract

Disclosed is a method for transmitting an acknowledgement signal in response to downlink data by a station (STA) in a wireless local area network (WLAN) system. To this end, the STA receives a downlink physical protocol data unit (PPDU) including a control information subfield for uplink scheduling information and downlink data from an access point (AP) and transmits, to the AP, an uplink PPDU including an acknowledgement signal in response to the downlink data according to the uplink scheduling information. In this case, the control information subfield may include length information of the uplink PPDU, resource unit (RU) allocation information for the uplink PPDU, modulation and coding scheme (MCS) information for the uplink PPDU, transmit power of the AP, and target receive signal strength indicator (RSSI) information of the AP.

## Claims

### Claim 1

A method for transmitting an acknowledgement signal in response to downlink data by a station, STA, in a wireless local area network, WLAN, system, the method comprising:
receiving a downlink physical protocol data unit, PPDU, including:
a control information subfield for uplink scheduling information, and
downlink data
from an access point, AP; and
transmitting, to the AP, an uplink PPDU including an acknowledgement signal in response to the downlink data according to the uplink scheduling information,
wherein the control information subfield includes:
length information of the uplink PPDU,
resource unit, RU, allocation information for the uplink PPDU,
modulation and coding scheme, MCS, information for the uplink PPDU,
transmit power of the AP, and
target receive signal strength indicator, RSSI, information of the AP,
wherein when the downlink PPDU is received, the processor is configured to disable spatial reuse of the uplink PPDU by assuming that the control information subfield does not include spatial reuse information.

### Claim 2

(canceled)

### Claim 3 (depends on 1)

The method of claim 1, wherein when receiving the downlink PPDU, the STA is configured to change a cyclic prefix, CP, and long training field, LTF, structure into one of two structures:
(1) a structure in which a 4× LTF and a 3.2 us CP are used; and
(2) a structure in which a 2× LTF and a 1.6 us CP are used.

### Claim 4 (depends on 1)

The method of claim 1, wherein the control information subfield does not include dual carrier modulation, DCM, information, and wherein the STA is configured to determine whether to apply DCM to the uplink PPDU in consideration of an MCS of the downlink PPDU.

### Claim 5 (depends on 1)

The method of claim 1, wherein the control information subfield does not include bandwidth information, and wherein the STA is configured to set a bandwidth of the uplink PPDU to be identical to a bandwidth of the downlink PPDU.

### Claim 6 (depends on 1)

The method of claim 1, wherein the control information subfield does not include information on a multi-user multi-input multi-output long training field, MU MIMO LTF, mode, a space time block code, STBC, the number of streams, a stream allocation, and a coding type, and wherein when receiving the downlink PPDU, the STA is configured to set parameters for the MU MIMO LTF mode, the STBC, the number of streams, the stream allocation, and the coding type to 0.

### Claim 7 (depends on 1)

The method of claim 1, wherein the MCS information has a length of 2 bits, and wherein the STA is configured to select an MCS level corresponding to the MCS information from four lowest MCS levels among a plurality of predetermined MCS levels.

### Claim 8 (depends on 1)

The method of claim 1, wherein the uplink PPDU includes one of an individual acknowledgement signal, a block acknowledgement, BA, signal, and a multi-STA BA signal in response to the downlink data.

### Claim 9 (depends on 1)

The method of claim 1, wherein the control information subfield has a length of 30 bits by additionally including 4 bits of control ID information, and wherein the length information of the uplink PPDU has a length of 5 bits.

### Claim 10

A station, STA, for transmitting an acknowledgement signal in response to downlink data in a wireless local area network, WLAN, system, the STA comprising:
a transceiver configured to receive a downlink physical protocol data unit, PPDU, including:
a control information subfield for uplink scheduling information, and
downlink data
from an access point, AP; and
a processor configured to process the uplink scheduling information and control the transceiver to transmit an uplink PPDU including an acknowledgement signal in response to the downlink data to the AP,
wherein the processor is configured to process the uplink scheduling information by assuming that the control information subfield includes:
length information of the uplink PPDU,
resource unit (RU) allocation information for the uplink PPDU,
modulation and coding scheme (MCS) information for the uplink PPDU,
transmit power of the AP, and
target receive signal strength indicator (RSSI) information of the AP,
wherein when the downlink PPDU is received, the processor is configured to disable spatial reuse of the uplink PPDU by assuming that the control information subfield does not include spatial reuse information.

### Claim 11

(canceled)

### Claim 12 (depends on 10)

The STA of claim 10, wherein when the downlink PPDU is received, the processor is configured to change a cyclic prefix, CP, and long training field, LTF, structure into one of two structures:
(1) a structure in which a 4× LTF and a 3.2 us CP are used; and
(2) a structure in which a 2× LTF and a 1.6 us CP are used.

### Claim 13 (depends on 10)

The STA of claim 10, wherein the processor is configured to determine whether to apply dual carrier modulation, DCM, to the uplink PPDU in consideration of an MCS of the downlink PPDU by assuming that the control information subfield does not include DCM information.

### Claim 14

A method for receiving an acknowledgement signal in response to downlink data from a station, STA, by an access point, AP, in a wireless local area network, WLAN, system, the method comprising:
transmitting a downlink physical protocol data unit, PPDU, including:
a control information subfield for uplink scheduling information, and
downlink data
to the STA; and
receiving, from the STA, an uplink PPDU including an acknowledgement signal in response to the downlink data according to the uplink scheduling information,
wherein the control information subfield includes:
length information of the uplink PPDU,
resource unit, RU, allocation information for the uplink PPDU,
modulation and coding scheme, MCS, information for the uplink PPDU,
transmit power of the AP, and
target receive signal strength indicator, RSSI, information of the AP,
wherein the control information subfield does not include spatial reuse information, and wherein the AP process signals from the STA assuming that the STA is configured to disable spatial reuse in response to receiving the downlink PPDU.

### Claim 15

(canceled)