CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage application under 35 U.S.C. § 371 of International Application No. PCT/KR2019/010661, filed on Aug. 22, 2019, which claims the benefit of Korean Patent Application Nos. 10-2018-0098869, filed on Aug. 23, 2018, and 10-2018-0099503, filed on Aug. 24, 2018. The disclosures of the prior applications are incorporated by reference in their entirety.

BACKGROUND

Technical Field

The present specification relates to a technique for transmitting and receiving data in wireless communication and, more particularly, to a method and a device for forwarding information about the size of a resource unit for an uplink in a wireless local area network (WLAN) system.

Related Art

Institute of Electrical and Electronics Engineers (IEEE) 802.11 is a technology used in wireless computer networking for a wireless local area network, commonly referred to as a WLAN or Wi-Fi. Specifically, IEEE 802.11 refers to a standard developed by the eleventh working group of the IEEE LAN Standards Committee (IEEE 802).

IEEE 802.11 is a technology designed to compensate for the shortcomings of Ethernet as a wired LAN. IEEE 802.11 is deployed at the end of an Ethernet network and is widely used to minimize unnecessary wiring and maintenance costs.

WLAN technology has evolved through IEEE 802.11/11b/11a/11g/11n in early stages. For example, IEEE 802.11n(i.e., a high throughput or HT standard) is known as a communication standard employing a 2.4 GHz band and a 5 GHz band and supporting a speed of up to 600 Mbps.

The WLAN has been further developed through IEEE 802.11ac (i.e., a very high throughput or VHT standard). For example, IEEE 802.11ac (VHT standard) supports a 160 MHZ channel, supports up to eight spatial streams (SSs) through improved multiple-input multiple-output (multi-user multiple-input multiple-output (MU-MIMO)), and supports MU-MIMO for a downlink (DL).

The WLAN has been further developed through IEEE 802.11ax (or high-efficiency or HE standard). IEEE 802.11ax supports a combination of orthogonal frequency-division multiple access (OFDMA) and downlink MU-MIMO. Further, IEEE 802.11ax also supports MU communication for an uplink (UL).

The present specification proposes technical features to improve a legacy WLAN or to be utilized in a new communication standard. For example, the technical features of the present specification may further improve IEEE 802.11ax. Alternatively, the technical features of the present specification can further improve IEEE 802.11be (i.e., extremely high throughput (ETH)) standard).

SUMMARY

When a STA exists at the boundary of a basic service set (BSS), when a problem occurs in a channel environment, or when surrounding interference is strong, the STA may have a problem in uplink communication. Specifically, the station STA may have difficulty in contention-based uplink communication. An example of contention-based uplink communication may be uplink communication based on enhanced distributed channel access (EDCA). For example, when the STA is located at the edge of a BSS, the STA may have difficulty in contention-based uplink transmission due to insufficient transmission power. Further, even though an access point (AP) performs scheduling through a trigger frame, it may be difficult to optimize scheduling depending on the STA.

In order to solve these problems, the present specification proposes an improved technique for controlling uplink communication.

An embodiment of the present specification relates to a method and/or a device for a wireless local area network (WLAN) system. The embodiment of the present specification may be applied to various STAs including an AP or a non-AP.

For example, an AP according to an embodiment of the present specification may receive a control message for link adaptation including a first field for a recommended resource unit (RU) of a station (STA), a second field for a recommended modulation and coding scheme (MCS) of the STA, and a third field related to an RU size for uplink multi-user (UL MU) communication of the STA from the STA.

For example, the AP may transmit a trigger frame to trigger the UL MU communication of the STA.

In this case, the size of an uplink RU allocated by the trigger frame may be determined based on a value of the third field.

The third field may have a first value, and the size of the uplink RU may be set equal to or smaller than a size of the recommended RU

An embodiment of the present specification provides an effect of controlling contention-based uplink communication. For example, an embodiment of the present specification proposes a function of disabling/inactivating contention-based uplink access. Accordingly, a STA performs uplink communication through an uplink multi-user (UL MU) scheme based on a trigger frame. As a result, the STA may normally perform uplink communication even in a situation where contention-based access is difficult.

In addition, an embodiment of the present specification proposes transmitting identification information about whether to use uplink communication using a narrowband and information about a resource unit for narrowband uplink communication. Accordingly, an AP may schedule uplink communication with a width equal to or less than a preferred/recommended size transmitted by a STA, thereby increasing the success rate of uplink communication.

