KR20170080601A - FDR transmission technique in wireless LAN system and apparatus therefor - Google Patents

Abstract

This document describes a FDR transmission technique and a device therefor in a wireless LAN system.
In a wireless LAN system, a station (STA) is configured to simultaneously transmit data through other subbands in a channel through which data is transmitted by an AP. The sub-band is used by the AP to transmit data based on header information of data transmitted by the AP. It is possible to determine whether or not to use subbands separated by a predetermined guard band from the subbands.

Description

FDR transmission technique in wireless LAN system and apparatus therefor

The following description relates to a FDR transmission technique and a device therefor in a wireless communication system, particularly a wireless LAN system.

Hereinafter, a wireless local area network (WLAN) system will be described as an example of a system to which the present invention can be applied, although the downlink channel proposed below can be applied to various wireless communications.

Recently, various wireless communication technologies have been developed along with the development of information communication technologies. The wireless LAN (WLAN) may be a home network, an enterprise, a home network, a home network, a home network, a home network, a home network, a home network, A technology that enables wireless access to the Internet from a specific service area.

The standard for wireless LAN technology is being developed as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. IEEE 802.11a and b 2.4. GHz or 5 GHz, the IEEE 802.11b provides a transmission rate of 11 Mbps, and the IEEE 802.11a provides a transmission rate of 54 Mbps. IEEE 802.11g employs Orthogonal Frequency-Division Multiplexing (OFDM) at 2.4 GHz to provide a transmission rate of 54 Mbps. IEEE 802.11n employs multiple input multiple output (OFDM), or OFDM (MIMO-OFDM), and provides transmission speeds of 300 Mbps for four spatial streams. IEEE 802.11n supports channel bandwidth up to 40 MHz, which in this case provides a transmission rate of 600 Mbps.

The IEEE 802.11ax standard, which supports a maximum of 160 MHz bandwidth and supports 8 spatial streams, supports a maximum speed of 1 Gbit / s, and discusses IEEE 802.11ax standardization.

Full Duplex Radio (FDR) technology, which is currently under development, has the advantage of simultaneous transmission and reception, so it can be expected to improve performance when applied to various communication systems. In the following description of the present invention, an FDR is applied to an IEEE 802.11 system. However, since the IEEE 802.11 system operates on several channels based on CSMA-CA, there are technical problems to be taken into consideration when applying FDR.

According to an aspect of the present invention, there is provided a method for transmitting data from a first station to a first access point in a wireless LAN system, Band through the first sub-band in the one wireless channel during the first data transmission of the specific AP and transmits the second data to the first AP through the second sub- Wherein the first STA determines whether to select the second subband as a subband separated by a predetermined guard band from the first subband according to the preamble information of the first data, We propose a transmission method.

According to another aspect of the present invention, there is provided a method for transmitting data from a first access point (AP) to a first station (STA) in a wireless LAN system, And transmits the second data to the first STA through the second subband in the one wireless channel during the first data transmission of the specific STA, According to preamble information, the first AP determines whether to select the second subband as a subband separated by a predetermined guard band from the first subband.

According to another aspect of the present invention, there is provided a first station (STA) apparatus for transmitting data to a first access point (AP) in a wireless LAN system, the apparatus comprising: a transceiver configured to simultaneously transmit and receive signals through a single wireless channel; ; And a processor coupled to the transceiver to control operation of the transceiver, wherein when the processor verifies that a particular AP is transmitting first data to a particular STA through a first subband in the one wireless channel, The transceiver controls to transmit the second data to the first AP through the second subband in the one wireless channel during the first data transmission of the specific AP, And determines whether to select the second subband as a subband that is separated by the predetermined guard band from the first subband according to the first subband.

According to another aspect of the present invention, there is provided a first AP apparatus for transmitting data to a first station (STA) in a wireless LAN system, the apparatus comprising: a transceiver configured to simultaneously transmit and receive signals through a wireless channel; And a processor coupled to the transceiver to control operation of the transceiver, wherein if the processor determines that a particular STA is transmitting first data to a particular AP via a first subband in the one wireless channel, The transceiver controls to transmit the second data to the first STA through a second subband in the one wireless channel during the first data transmission of the specific STA, And determines whether to select the second subband as a subband that is separated by a predetermined guard band from the first subband according to the first subband.

As described above, according to the present invention, not only the transmission efficiency can be increased by applying the FDR in the data transmission in the wireless LAN system, but also the problem of inter-device / inter-device interference due to FDR application can be effectively solved.

1 is a diagram showing an example of a configuration of a wireless LAN system.
2 is a diagram showing another example of the configuration of the wireless LAN system.
3 is a diagram for explaining a DCF mechanism in a wireless LAN system.
Figures 4 and 5 are illustrations for explaining the problem of the existing conflict resolution mechanism.
6 is a diagram for explaining a mechanism for solving a hidden node problem using an RTS / CTS frame.
7 is a diagram for explaining a mechanism for solving an exposed node problem using an RTS / CTS frame.
FIG. 8 is a diagram for explaining a method of operating using the RTS / CTS frame as described above.
9 is a conceptual diagram of a terminal supporting a FDR in a wireless communication system and a base station.
10 shows a conceptual diagram of IDI that occurs when a base station uses the FD mode (simultaneous transmission / reception mode using the same frequency) in the same resource.
11 is a diagram for explaining a wireless LAN environment to which an embodiment of the present invention can be applied.
12 and 13 are diagrams for explaining a method of transmitting data to an AP by a terminal according to an embodiment of the present invention.
FIG. 14 shows a method of transmitting data to an AP without using a guard band in the situation shown in FIG.
15 is a diagram for explaining an apparatus for performing data transmission by applying the FDR as described above.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following detailed description, together with the accompanying drawings, is intended to illustrate exemplary embodiments of the invention and is not intended to represent the only embodiments in which the invention may be practiced.

The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, those skilled in the art will appreciate that the present invention may be practiced without these specific details. In some instances, well-known structures and devices are omitted or shown in block diagram form around the core functions of each structure and device in order to avoid obscuring the concepts of the present invention.

In the following description, the term "terminal" is a concept including an STA in a wireless LAN system and a UE in an LTE-A system as an arbitrary user equipment that performs a communication function.

As described above, the following description relates to an FDR transmission technique in a wireless LAN system and an apparatus therefor. To this end, a wireless LAN system to which the present invention is applied will be described in detail.

1 is a diagram showing an example of a configuration of a wireless LAN system.

As shown in FIG. 1, a WLAN system includes one or more Basic Service Sets (BSSs). A BSS is a collection of stations (STAs) that can successfully communicate and synchronize with each other.

An STA is a logical entity that includes a medium access control (MAC) and a physical layer interface to a wireless medium. The STA includes an access point (AP) and a non-AP STA (Non-AP Station) . A portable terminal operated by a user in the STA is a non-AP STA, and sometimes referred to as a non-AP STA. The non-AP STA may be a terminal, a wireless transmit / receive unit (WTRU), a user equipment (UE), a mobile station (MS), a mobile terminal, May also be referred to as another name such as a Mobile Subscriber Unit.

An AP is an entity that provides a connection to a distribution system (DS) via a wireless medium to an associated station (STA). The AP may be referred to as a centralized controller, a base station (BS), a Node-B, a base transceiver system (BTS), a site controller, or the like.

The BSS can be divided into an infrastructure BSS and an independent BSS (IBSS).

The BBS shown in FIG. 1 is an IBSS. The IBSS means a BSS that does not include an AP, and does not include an AP, so a connection to the DS is not allowed and forms a self-contained network.

2 is a diagram showing another example of the configuration of the wireless LAN system.

The BSS shown in FIG. 2 is an infrastructure BSS. The infrastructure BSS includes one or more STAs and APs. In the infrastructure BSS, communication between non-AP STAs is performed via an AP, but direct communication between non-AP STAs is possible when a direct link is established between non-AP STAs.

As shown in FIG. 2, a plurality of infrastructure BSSs may be interconnected via DS. A plurality of BSSs connected through a DS are referred to as an extended service set (ESS). The STAs included in the ESS can communicate with each other, and within the same ESS, the non-AP STA can move from one BSS to another while seamlessly communicating.

The DS is a mechanism for connecting a plurality of APs. It is not necessarily a network, and there is no limitation on the form of DS if it can provide a predetermined distribution service. For example, the DS may be a wireless network such as a mesh network, or may be a physical structure that links APs together.

Based on the above description, the collision detection technique in the wireless LAN system will be described.

As described above, in the wireless environment, various factors affect the channel, so that the transmitting terminal can not accurately perform the collision detection. Therefore, 802.11 introduced a distributed coordination function (DCF), a carrier sense multiple access / collision avoidance (CSMA / CA) mechanism.

3 is a diagram for explaining a DCF mechanism in a wireless LAN system.

The DCF performs clear channel assessment (CCA), which senses the medium for a certain period of time (for example, DIFS: DCF inter-frame space) before STAs with data to be transmitted transmit data. At this time, if the medium is idle, the STA can transmit signals using the medium. However, if the medium is busy, it is possible to transmit data after waiting for an additional random backoff period to the DIFS, assuming that several STAs are already waiting to use the medium. At this time, the random back-off period makes it possible to avoid the collision. Assuming that there are several STAs for transmitting data, each STA has a different backoff interval value stochastically, I have time. When one STA starts transmission, the other STAs will not be able to use the medium.

Here is a brief description of the random backoff time and procedure.

When a particular medium changes from busy to idle, several STAs start preparing to send data. At this time, in order to minimize the collision, each STA which desires to transmit data selects a random backoff count and waits for the slot time. The random backoff count is a pseudo-random integer value and selects one of the uniformly distributed values in the [0 CW] range. CW means 'contention window'.

The CW parameter takes the CWmin value as the initial value, but when the transmission fails, the value doubles. For example, if an ACK response to a transmitted data frame is not received, it can be regarded as a collision. If the CW value has a CWmax value, the CWmax value is maintained until the data transmission is successful, and the data transmission is successful and the CWmin value is reset. At this time, CW, CWmin, and CWmax are preferably maintained at 2 ⁿ - 1 for convenience of implementation and operation.

On the other hand, when the random backoff procedure is started, the STA selects a random backoff count within the [0 CW] range and continuously monitors the medium while the backoff slot counts down. Meanwhile, when the medium becomes busy, the countdown is stopped, and when the medium becomes idle again, the countdown of the remaining backoff slots is resumed.

Referring to FIG. 3, when there are data that a plurality of STAs desire to transmit, the STA 3 transmits data frames immediately since the medium is idle by DIFS, and the remaining STAs wait for the medium to become idle. Since the medium is busy for a while, several STAs will see the opportunity to use the medium. Thus, each STA selects a random backoff count. In FIG. 3, STA 2, which has selected the smallest backoff count at this time, shows that the data frame is transmitted.

After the transmission of the STA2 is finished, the medium becomes idle again, and the STAs resume the countdown of the backoff interval that has stopped again. FIG. 3 shows that STA 5, which had a small random backoff count after STA 2 and stopped countdown when the medium was busy, counted down the remaining backoff slots and then started transmitting data frames, It is shown that a collision occurs due to overlapping with the back-off count value. In this case, since both ACK responses are not received after two STA data transmission, the CW is doubled and the random backoff count value is selected again.

As already mentioned, the most basic of CSMA / CA is carrier sensing. The MS can use physical carrier sensing and virtual carrier sensing to determine whether the DCF medium is busy or idle. Physical carrier sensing is performed at the PHY (physical layer) stage and is performed through energy detection or preamble detection. For example, if the voltage level at the receiving end is measured or it is determined that the preamble has been read, it can be determined that the medium is busy. The virtual carrier sensing is performed by setting a network allocation vector (NAV) so that other STAs can not transmit data, and the value of the duration field of the MAC header is used. On the other hand, we introduced a robust collision detection mechanism to reduce the possibility of collision, which can be seen in the following two examples. For convenience, it is assumed that the carrier sensing range is equal to the transmission range.

Figures 4 and 5 are illustrations for explaining the problem of the existing conflict resolution mechanism.

Specifically, Figure 4 is a diagram for illustrating hidden node issues. In this example, STA A and STA B are communicating and STA C has information to transmit. Specifically, when STA C is transmitting information to STA B, STA C detects a signal transmission of STA A because it is outside the transmission range of STA A when carrier sensing the medium before sending data to STA B. It is possible that the medium is idle. As a result, STA B receives the information of STA A and STA C at the same time, resulting in collision. In this case, STA A is a hidden node of STA C.

Meanwhile, FIG. 5 is a diagram for explaining exposed node issues. Currently, STA B is transmitting data to STA A. At this time, STA C performs carrier sensing. Since STA B is transmitting information, it is detected that the medium is busy. As a result, although the STA C wants to transmit data to the STA D, since the medium is detected as busy, a situation occurs in which the medium is unnecessarily waiting until it becomes idle. That is, although the STA A is outside the CS range of the STA C, the STA C may be prevented from transmitting the information. At this time, STA C becomes an exposed node of STA B.

In order to better utilize the collision avoidance mechanism in the above-mentioned situation, it is possible to oversee the transmission of information between two STAs by introducing short signaling packets such as RTS (request to send) and CTS (clear to send) . That is, when the STA to which data is to be transmitted transmits an RTS frame to the STA receiving the data, the receiving STA can notify that it will receive the data by transmitting the CTS frame to surrounding terminals.

6 is a diagram for explaining a mechanism for solving a hidden node problem using an RTS / CTS frame.

In FIG. 6, both STA A and STA C attempt to transmit data to STA B. When STA A sends RTS to STA B, STA B transmits CTS to both STA A and STA C around it. As a result, STA C waits until data transmission between STA A and STA B is completed, thereby avoiding collision.

7 is a diagram for explaining a mechanism for solving an exposed node problem using an RTS / CTS frame.

In FIG. 7, overhearing of RTS / CTS transmission of STA A and STA B indicates that collision does not occur even if STA C transmits data to another STA. That is, STA B transmits RTS to all the surrounding terminals and only STA A having data to be transmitted transmits CTS. Since STA C only receives RTS and does not receive CTS of STA A, it can be seen that STA A is outside CS range of STC C.

FIG. 8 is a diagram for explaining a method of operating using the RTS / CTS frame as described above.

In FIG. 8, the transmitting STA can transmit an RTS frame to a receiving STA to which a signal after DIFF (Distributed IFS) is to be transmitted. The receiving STA receiving the RTS frame can transmit the CTS to the transmitting STA after SIFS (Short IFS). The transmitting station STA receiving the CTS from the receiving station STA can transmit data after SIFS as shown in FIG. The receiving STA receiving the data may transmit an ACK response to the data received after SIFS.

On the other hand, the STA receiving the RTS / CTS of the transmitting STA among the neighboring STAs other than the transmitting / receiving STA determines whether the medium is busy through the RTS / CTS reception as described above with reference to FIGS. 6 and 7 , And thus a network allocation vector (NAV) can be set. When the NAV period ends, the process for conflict resolution as described above with reference to FIG. 3 can be performed after the DIFS.

Full duplex radio (FDR) refers to a system that simultaneously supports transmission and reception using the same resources in a transmission device. At this time, the same resource can mean the same time, the same frequency.

9 is a conceptual diagram of a terminal supporting a FDR in a wireless communication system and a base station. The system shown in FIG. 9 assumes a system in which LTE or LTE-A based macro base stations (eNB) and small base stations (Femto, Pico / Micro) base stations are mixed.

In this situation, there are two types of interference due to FDR support.

Intra-device interference

A signal transmitted from a transmission antenna at a base station or a terminal is received by a reception antenna and acts as interference.

Inter-device interference

Means that an uplink signal transmitted from a base station or a terminal is received by a neighboring base station or a terminal and acts as interference.

Inter-device interference (IDI) is an interference that occurs only in FDR due to the use of the same resources in a cell.

10 shows a conceptual diagram of IDI that occurs when a base station uses the FD mode (simultaneous transmission / reception mode using the same frequency) in the same resource.

10 is a simple illustration showing two UEs (UE1 and UE2) for ease of description of IDI, and the present invention does not limit the number of UEs.

In a conventional full-duplex communication system, the frequency division duplex (FDD) or the time division duplex (TDD) is used. The interference of neighboring cells on the existing communication system is still valid in the FDR system, but a description thereof will be omitted.

If the FDR is applied to an IEEE 802.11 system, the biggest problem may be interference between DL and UL. In the past, there was only UL or DL at a specific time in one network, but DL and UL exist when FDR is applied. In this case, if the DL and UL channels are adjacent to each other, interference occurs. An embodiment of the present invention will be described below.

11 is a diagram for explaining a wireless LAN environment to which an embodiment of the present invention can be applied.

As described above, the present invention relates to a terminal / STA supporting FDR, but the application of the FDR does not assume that signals are simultaneously transmitted and received through subbands in the same channel. That is, although UL and DL communication are possible in one channel at the same time, it is assumed that UL and DL communicate via different subbands, respectively.

For example, it is assumed that the subband in which the AP in FIG. 11 transmits data to the STA supporting the FDR and the subband in which the STA supporting the FDR transmit data to the AP are different from each other.

Meanwhile, it is assumed that the AP according to the present embodiment supports not only the terminal / STA supporting the FDR but also the terminal / STA not supporting the conventional FDR as shown in FIG.

12 and 13 are diagrams for explaining a method of transmitting data to an AP by a terminal according to an embodiment of the present invention.

In Figures 12-13 and the following description of the embodiments, the "subband" may be a 20 MHz channel in 802.11 or a Resource unit smaller than a 20 MHz channel when OFDMA is applied. The part denoted by "AP- > STA " indicates the DL PPDU being transmitted by the AP, which may be configured to include a PLCP preamble and a header. The part labeled "STA-> AP" indicates the PPDU that the STA is transmitting.

First, the AP can start transmission on a particular subband. The PLCP header of the PPDU transmitted by the AP may include the address of the currently transmitted AP or the BSS color information. Through this information, terminals can know that their own AP is currently transmitting data.

The BSS color information transmitted through the PLCP header is defined in the IEEE 802.11ah standard as information for controlling the receiving operation by distinguishing the BSS from which the receiving terminal transmits data.

At this time, if there is a frame to be transmitted to the AP, the terminal can transmit data using an empty subband. However, since the AP is currently transmitting data, UL / DL interference occurs between adjacent channels when transmitting directly in an adjacent subband. Therefore, it is proposed to transmit a certain guard band (or guard subband).

On the other hand, if the AP currently transmitting data through the information of the PLCP Header is not its own AP, the terminal can transmit without transmitting a guard band as shown in FIG. Since the AP is not transmitting, it is not necessary to consider UL / DL interference between adjacent channels.

The following information may be added to the PLCP header information described in the embodiment of the present invention as described above.

Whether the guard band is used: The terminal can indicate whether the guard band should be used when transmitting the FDR to the remaining subband. If the decoding performance of the AP is good, the guard band may not be needed.

Guard Band Size: It specifies the size of the guard band when the terminal should transmit it. This may vary depending on the performance of the AP and the subband size of the PPDU being transmitted.

As described above, the terminal / STA can determine whether or not the guard band is applied in the FDR operation through the information of the PLCP header. For this, it is desirable that the terminal / STA does not start data transmission to the AP until it receives (decodes) the PLCP header information of the PPDU of the AP as shown in Fig. 12 and Fig. After completing the reception of the PLCP header information, the terminal / STA can initiate data transmission to the AP via the contention step in the corresponding subband as indicated by "backoff ".

FIG. 14 shows a method of transmitting data to an AP without using a guard band in the situation shown in FIG.

As shown in FIG. 14, when no guard band is used, since there is DL / UL interference between adjacent channels, it is necessary to use a slightly more robust MCS (i.e., a lower MCS) desirable. Alternatively, a method of lowering data transmission power is also possible in order to transmit data without a guard band.

In summary, when the guard band is not used, the transmission power is P1, the MCS level is MCS 1, the transmission power when the guard band is used is P2, and the MCS level is MCS 2,

(1) P1 < P2, or

(2) MCS 1 < MCS2

Is satisfied.

It is also possible to transmit the RTS frame to the AP before transmitting the data frame to the AP, measure the interference caused by the RTS while the AP responds with the CTS, and then determine the appropriate MCS. Also, the size of guard band can be informed through CTS.

The description of FIGS. 12 to 14 described above only describes a situation in which UL transmission is performed during DL transmission, but the opposite case is also possible. That is, the AP may determine whether the guard band is used based on the header information of the data transmitted by the STA while the specific STA is transmitting data to the specific AP.

15 is a diagram for explaining an apparatus for performing data transmission by applying the FDR as described above.

The wireless device 800 of FIG. 15 may correspond to the specific STA of the above description, and the wireless device 850 of the above description.

The STA may include a processor 810, a memory 820 and a transceiver 830, and the AP 850 may include a processor 860, a memory 870, and a transceiver 880. The transceivers 830 and 880 transmit / receive wireless signals and may be implemented in a physical layer such as IEEE 802.11 / 3GPP. Processors 810 and 860 are implemented in the physical layer and / or MAC layer and are coupled to transceivers 830 and 880. Processors 810 and 860 may perform the interference control procedures described above.

Processors 810 and 860 and / or transceivers 830 and 880 may include application specific integrated circuits (ASICs), other chipsets, logic circuits, and / or data processors. Memory 820 and 870 may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage media and / or other storage units. When an embodiment is executed by software, the method described above may be executed as a module (e.g., process, function) that performs the functions described above. The module may be stored in memory 820, 870 and executed by processor 810, 860. The memory 820, 870 may be located inside or outside the processes 810, 860 and may be coupled to the processes 810, 860 by well known means.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The foregoing description of the preferred embodiments of the present invention has been presented for those skilled in the art to make and use the invention. While the foregoing is directed to preferred embodiments of the present invention, those skilled in the art will appreciate that various modifications and changes may be made by those skilled in the art from the foregoing description. Accordingly, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Although the present invention has been described on the assumption that the present invention is applied to an IEEE 802.11 based wireless LAN system, the present invention is not limited thereto. The present invention may be applied in a similar manner to various wireless systems requiring interference control between wireless devices.

Claims (11)

A method for transmitting data from a first station (STA) to a first access point (AP) in a wireless LAN system,
Confirms that the specific AP is transmitting the first data to the specific STA through the first subband in one radio channel,
Transmitting the second data to the first AP through the second subband in the one wireless channel during the first data transmission of the specific AP,
Wherein the first STA determines whether to select the second subband as a subband separated by a predetermined guard band from the first subband according to the preamble information of the first data. The method according to claim 1,
When the preamble information of the first data indicates that the specific AP is the first AP, the first STA selects the second subband as a subband separated by a predetermined guard band from the first subband, Transmission method. The method according to claim 1,
Wherein the first STA selects the second subband as a subband adjacent to the first subband if the preamble information of the first data indicates that the specific AP is a second AP rather than the first AP. Data transmission method. The method according to claim 1,
When the preamble information of the first data indicates that the predetermined guard band is not needed, the first STA selects the second subband as a subband adjacent to the first subband. The method according to claim 1,
Wherein when the first STA selects the second subband as a subband adjacent to the first subband, the first transmission power for the second data transmission and the first modulation and coding scheme (MCS)
Comparing the second transmit power and the second MCS level for the second data transmission when the first STA selects the second subband as a subband separated by a predetermined guard band from the first subband,
(1) first transmission power < second transmission power, or
(2) First MCS level < Second MCS level
Lt; / RTI > The method according to claim 1,
Wherein the preamble information of the first data includes information on whether the predetermined guard band is used and information on the size of the predetermined guard band. The method according to claim 1,
Wherein the transmission of the second data to the first AP is performed during the first data transmission of the specific AP, but after the reception of the preamble information of the first data. The method according to claim 1,
Wherein the first data is a PLCP Protocol Data Unit (PPDU) including a Physical Layer Convergence Procedure (PLCP) preamble, a header, and an MPDU (MAC Protocol Data Unit). A method for transmitting data from a first access point (AP) to a first station (STA) in a wireless LAN system,
Confirms that the particular STA is transmitting the first data to the specific AP through the first subband in one radio channel,
Transmitting the second data to the first STA through a second subband in the one wireless channel during the first data transmission of the specific STA,
Wherein the first AP determines whether to select the second subband as a subband separated by a predetermined guard band from the first subband according to the preamble information of the first data. A first station (STA) apparatus for transmitting data to a first access point (AP) in a wireless LAN system,
A transceiver configured to simultaneously transmit and receive signals through one wireless channel; And
And a processor coupled to the transceiver to control operation of the transceiver,
Wherein if the processor confirms that a particular AP is transmitting first data to a particular STA on a first subband in the one wireless channel, Wherein the transceiver controls to transmit the second data to the first AP through a subband,
Wherein the processor determines whether to select the second subband as a subband separated by a predetermined guard band from the first subband according to the preamble information of the first data. A first AP apparatus for transmitting data to a first station (STA) in a wireless LAN system,
A transceiver configured to simultaneously transmit and receive signals through one wireless channel; And
And a processor coupled to the transceiver to control operation of the transceiver,
When the processor confirms that a particular STA is transmitting first data to a specific AP through a first subband in the one wireless channel, The transceiver controls to transmit the second data to the first STA through a subband,
Wherein the processor determines whether to select the second subband as a subband separated by a predetermined guard band from the first subband according to the preamble information of the first data.

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