WO2020027634A1 - Method and device for transmitting traffic in wireless lan system - Google Patents

Abstract

A method and a device for transmitting traffic in a wireless LAN system are presented. Particularly, an AP generates first traffic to third traffic. The AP performs carrier sensing on a multi-band, and transmits first traffic to a first STA through the multi-band on the basis of the carrier sensing result. In the multi-band, a first band and a second band are combined. The carrier sensing is performed on the basis of a first BC value for the first band. The carrier sensing is performed on the basis of a second BC value for the second band. The AP and the first STA support the multi-band.

Description

Method and apparatus for transmitting traffic in WLAN system

The present disclosure relates to a technique for transmitting traffic in a WLAN system, and more particularly, to a method and apparatus for performing carrier sensing for multiple bands in a WLAN system.

Discussion is underway for the next generation wireless local area network (WLAN). In next-generation WLANs: 1) enhancements to the Institute of Electronic and Electronics Engineers (IEEE) 802.11 physical layer (PHY) and medium access control (MAC) layers in the 2.4 GHz and 5 GHz bands, and 2) spectral efficiency and area throughput. aims to improve performance in real indoor and outdoor environments, such as in environments where interference sources exist, dense heterogeneous network environments, and high user loads.

The environment mainly considered in next-generation WLAN is a dense environment with many access points and STAs, and improvements in spectral efficiency and area throughput are discussed in such a dense environment. In addition, in the next generation WLAN, there is an interest in improving practical performance not only in an indoor environment but also in an outdoor environment, which is not much considered in a conventional WLAN.

Specifically, in the next-generation WLAN, there is a great interest in scenarios such as wireless office, smart home, stadium, hotspot, building / apartment, and AP based on the scenario. And STA are discussing about improving system performance in a dense environment with many STAs.

In addition, in the next-generation WLAN, there will be more discussion about improving system performance in outdoor overlapping basic service set (OBSS) environment, improving outdoor environment performance, and cellular offloading, rather than improving single link performance in one basic service set (BSS). It is expected. The directionality of these next-generation WLANs means that next-generation WLANs will increasingly have a technology range similar to that of mobile communications. Considering the recent situation in which mobile communication and WLAN technologies are discussed together in the small cell and direct-to-direct (D2D) communication area, the technical and business convergence of next-generation WLAN and mobile communication is expected to become more active.

The present specification proposes a method and apparatus for transmitting traffic in a WLAN system.

One example of the present specification proposes a method of transmitting traffic.

This embodiment may be performed in a network environment in which a next generation WLAN system is supported. The next generation WLAN system is a WLAN system that improves the 802.11ax system and may satisfy backward compatibility with the 802.11ax system. The next generation WLAN system may correspond to an Extreme High Throughput (ETH) WLAN system or an 802.11be WLAN system.

This embodiment proposes a method for performing band-specific (or link) EDCA in a multi-band (or multi-link) environment in a next-generation wireless LAN system such as EHT.

This embodiment is performed in an AP, and the receiving apparatus of this embodiment may correspond to an STA supporting an Extremely High Throughput (ETH) wireless LAN system.

An access point (AP) generates first to third traffic.

The AP performs carrier sensing on multi-bands.

The AP transmits the first traffic to the first STA through the multi-band based on the result of the carrier sensing.

The multi band is aggregated with a first band and a second band. The first band includes a first primary channel and the second band includes a second primary channel.

If the multiple bands are combined into only two bands, the first band may be a 2.4 GHz or 5 GHz band, and the second band may be a 6 GHz band. If the third band is further combined with the third band, the first band may be a 2.4 GHz band, the second band may be a 5 GHz band, and the third band may be a 6 GHz band. However, the above-described configuration of the band is just one example, and the WLAN system may support various numbers of bands and channels.

The carrier sensing may be performed separately while simultaneously performing the first and second bands. In detail, the carrier sensing is performed based on a first backoff count (BC) value for the first band. The carrier sensing is performed based on a second BC value for the second band.

In addition, the carrier sensing may include physical carrier sensing and virtual carrier sensing. The physical carrier sensing may correspond to carrier sensing such as clear channel assessment (CCA), and the virtual carrier sensing may correspond to carrier sensing such as NAV (Network Allocation Vector) configuration. The physical carrier sensing and the virtual carrier sensing may be performed on the first and second primary channels.

In this case, the AP and the first STA support the multi-band.

When the first BC value becomes 0, the first traffic may be transmitted through the first band. When the second BC value becomes 0, the second traffic may be transmitted through the second band. That is, the AP may first transmit data (or traffic) to the STA through the band for the BC value which becomes 0. For example, if the first BC value becomes 0 first, the AP may perform carrier sensing for the second band even while transmitting the first traffic to the first STA. When the channel of the second band is idle, the second BC value is decreased, and when the second BC value is 0, the AP can transmit the second traffic to the first STA through the second band. have.

Carrier sensing for the first and second bands may correspond to carrier sensing for the first and second primary channels. Hereinafter, an embodiment in which the first traffic is transmitted based on carrier sensing in the first and second primary channels.

When it is determined that the first primary channel is idle, the first BC value may decrease. If it is determined that the second primary channel is idle, the second BC value may decrease. When the first and second BC values become zero, the first traffic may be transmitted through the first and second primary channels.

In addition, the AP may transmit traffic by performing carrier sensing to an STA that supports only a single band.

The AP may transmit the second traffic to a second STA based on a result of the carrier sensing. In addition, the AP may transmit the third traffic to a third STA based on a result of the carrier sensing.

When the first BC value becomes 0, the second traffic may be transmitted to the second STA through the first band. When the second BC value becomes 0, the third traffic may be transmitted to the third STA through the second band.

In this case, the second STA may support only the first band, and the third STA may support only the second band.

According to the embodiment described above, when the first BC value becomes 0, the AP may transmit the second traffic to the second STA through the first band. However, when performing the EDCA between the AP and the second STA, there may be a case where the second BC value becomes zero before the first BC value. Hereinafter, an EDCA method between the AP and the second STA will be described in consideration of the priority of the second traffic with other traffic.

If the second BC value becomes zero before the first BC value, if the second traffic has a higher priority than the third traffic, the first BC value is zero until the first BC value becomes zero. The 2 BC value can be reset. That is, the second traffic should be transmitted before the third traffic, but since the first BC value is not zero, the second traffic cannot be sent yet. In addition, the second traffic may not be transmitted to the second STA through the second band. Accordingly, the AP may randomly extract the second BC value again until the first BC value becomes zero.

When the second BC value becomes zero before the first BC value, if the second traffic has no priority with the third traffic, the third traffic may be transmitted before the second traffic. In other words, if there is no priority of traffic, it should be able to transmit any traffic first if it is ready to transmit regardless of traffic order. Accordingly, the AP may transmit the third traffic to the third STA before the second traffic. However, for fairness with terminals such as a second STA using only the first band, when the third traffic is sent, the first band and the second band are not aggregated even when the first band is idle. And transmits the third traffic using only the second band. Accordingly, the transmission opportunity of the STA using only the first band can be balanced with the transmission opportunity of the STA using the first and second bands at the same time.

The first to third traffic may be buffered for each access category (AC). The AC may include AC_VO (Voice), AC_VI (Video), AC_BE (Best Effort), and AC_BK (Background) as previously defined. For each AC the BC value can be set per band.

In addition, a new AC may be defined as follows by newly defining an EDCA Parameter Set element considering multi-band (or multi-link) operation. The first traffic may be buffered in AC for the multiple bands. The second traffic may be buffered in AC for the first band. The third traffic may be buffered in AC for the second band. The BC value for the AC for the multi-band can be set for each band. A first BC value may be set for AC for the first band. A second BC value may be set for the AC for the second band.

Hereinafter, a signaling scheme for multi-band aggregation will be described. In the present embodiment, it has been described as receiving configuration information for multiple bands, and signaling may be performed by using an FST configuration scheme.

The transmitter may transmit the multi-band setup request frame to the receiver. The transmitter may receive a multi-band setup response frame from the receiver.

The transmitter may transmit a multi-band Ack request frame to the receiver. The transmitter may receive a multi-band Ack response frame from the receiver.

The transmitter may include a first station management entity (SME), a first MAC layer management entity (MLME), and a second MLME. The receiver may include a second SME, a third MLME, and a fourth MLME.

The first MLME and the third MLME may be an entity supporting the first band, and the second MLME and the fourth MLME may be an entity supporting the second band.

The multi-band configuration request frame and the multi-band configuration response frame may be transmitted and received between the first MLME and the third MLME. The multi-band Ack request frame and the multi-band Ack response frame may be transmitted and received between the second MLME and the fourth MLME.

The first and second SMEs may generate primitives including multi-band parameters. The multiband parameter may include a channel number, an operating class, and a band identifier designated in the multiband. The primitive may be delivered to the first to fourth MLME.

When the multi-band method employs the FST setting method, the multi-band method includes four states, and includes rules on how to move from one state to the next state. The four states are Initial, Setup Completed, Transition Done, and Transition Confirmed.

In the Initial state, the transmitter and the receiver communicate in the old band / channel. At this time, when the FST setting request frame and the FST setting response frame are transmitted / received between the transmitter and the receiver, the apparatus moves to the Setup Complete state, and the transmitter and the receiver are ready to change the currently operating band / channel (s). do. FST sessions may be delivered in whole or in part to other bands / channels.

When the value of the LLT included in the FST setup request frame is 0, the LLT moves from the Setup Complete state to the Transition Done state, and enables the transmitter and the receiver to operate in different bands / channels.

Both the transmitter and receiver must successfully communicate on the new band / channel to reach the Transition Confirmed state. At this time, when the FST Ack request frame and the FST Ack response frame are transmitted / received between the transmitter and the receiver, the UE moves to the Transition Confirmed state, and the transmitter and the receiver form a complete connection in a new band / channel.

According to the embodiment proposed in the present specification, a new carrier sensing method for transmitting traffic for multiple bands may be performed to reduce collision probability and enable efficient data transmission.

1 is a conceptual diagram illustrating a structure of a wireless local area network (WLAN).

2 is a diagram illustrating an example of a PPDU used in the IEEE standard.

3 is a diagram illustrating an example of a HE PPDU.

4 is a diagram illustrating an arrangement of resource units (RUs) used on a 20 MHz band.

5 is a diagram illustrating an arrangement of resource units (RUs) used on a 40 MHz band.

6 is a diagram illustrating an arrangement of resource units (RUs) used on an 80 MHz band.

7 is a diagram illustrating another example of the HE-PPDU.

8 is a block diagram showing an example of the HE-SIG-B according to the present embodiment.

9 shows an example of a trigger frame.

10 illustrates an example of subfields included in a per user information field.

11 is a block diagram showing an example of a control field and a data field constructed according to the present embodiment.

12 is a diagram illustrating an example of a HE TB PPDU.

13 shows a number of channels allocated in the 5 GHz band.

14 shows four states of the FST setting protocol.

15 shows a procedure of an FST setting protocol.

16 shows an example of multi-band aggregation using a 2.4 GHz band and a 5 GHz band.

17 illustrates an example in which a primary channel exists in each band (or RF) when multi-band aggregation is performed.

FIG. 18 shows an example of applying the BC decrement rule of the method B-2) when the 2.4 GHz, 5 GHz, and 6 GHz bands are aggregated.

19 shows an example of a BSS that simultaneously supports multi-band using band 1 and band 2.

20 shows an example of segmenting EDCA traffic by band.

21 shows another example of segmenting EDCA traffic by band.

22 illustrates multi-band aggregation and flexible DL / UL scheme.

FIG. 23 illustrates a relationship between AC and BC for each AC used when a terminal having multi-band capability transmits data.

24 illustrates an example in which EDCAs in various cases are performed in a BSS that simultaneously supports multi-band using band 1 and band 2.

25 illustrates an example in which EDCA between an AP having a multi-band capability and an STA is performed.

FIG. 26 illustrates an example in which EDCA is performed between an AP having a multi band capability and an STA having a single band capability.

FIG. 27 shows another example in which EDCA is performed between an AP having a multi band capability and an STA having a single band capability.

28 shows an example of AC defined in a multi-band environment.

29 is a flowchart illustrating a procedure of transmitting traffic according to the present embodiment.

30 is a flowchart illustrating a procedure of receiving traffic according to the present embodiment.

FIG. 31 illustrates an apparatus for implementing the method as described above.

32 illustrates a more detailed wireless device implementing an embodiment of the present invention.

1 is a conceptual diagram illustrating a structure of a wireless local area network (WLAN).

1 shows the structure of the infrastructure basic service set (BSS) of the Institute of Electrical and Electronic Engineers (IEEE) 802.11.

Referring to the top of FIG. 1, the WLAN system may include one or more infrastructure BSSs 100 and 105 (hereinafter, BSS). The BSSs 100 and 105 are a set of APs and STAs such as an access point 125 and a STA1 (Station 100-1) capable of successfully synchronizing and communicating with each other, and do not indicate a specific area. The BSS 105 may include one or more STAs 103-1 and 105-2 that can be coupled to one AP 130.

The BSS may include at least one STA, APs 125 and 130 for providing a distribution service, and a distribution system (DS) 110 for connecting a plurality of APs.

The distributed system 110 may connect several BSSs 100 and 105 to implement an extended service set (ESS) 140 which is an extended service set. The ESS 140 may be used as a term indicating one network in which one or several APs 125 and 230 are connected through the distributed system 110. APs included in one ESS 140 may have the same service set identification (SSID).

The portal 120 may serve as a bridge for connecting the WLAN network (IEEE 802.11) to another network (eg, 802.X).

In the BSS as shown in the upper part of FIG. 1, a network between the APs 125 and 130 and a network between the APs 125 and 130 and the STAs 100-1, 105-1 and 105-2 may be implemented. However, it may be possible to perform communication by setting up a network even between STAs without the APs 125 and 130. A network that performs communication by establishing a network even between STAs without APs 125 and 130 is defined as an ad-hoc network or an independent basic service set (BSS).

1 is a conceptual diagram illustrating an IBSS.

Referring to the bottom of FIG. 1, the IBSS is a BSS operating in an ad-hoc mode. Since IBSS does not contain an AP, there is no centralized management entity. That is, in the IBSS, the STAs 150-1, 150-2, 150-3, 155-4, and 155-5 are managed in a distributed manner. In the IBSS, all STAs 150-1, 150-2, 150-3, 155-4, and 155-5 may be mobile STAs, and are not allowed to access a distributed system, and thus are self-contained. network).

A STA is any functional medium that includes medium access control (MAC) and physical layer interface to a wireless medium that is compliant with the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. May be used to mean both an AP and a non-AP STA (Non-AP Station).

The STA may include a mobile terminal, a wireless device, a wireless transmit / receive unit (WTRU), a user equipment (UE), a mobile station (MS), a mobile subscriber unit ( It may also be called various names such as a mobile subscriber unit) or simply a user.

On the other hand, the term "user" may be used in various meanings, for example, may also be used to mean an STA participating in uplink MU MIMO and / or uplink OFDMA transmission in wireless LAN communication. It is not limited to this.

2 is a diagram illustrating an example of a PPDU used in the IEEE standard.

As shown, various types of PHY protocol data units (PPDUs) have been used in the IEEE a / g / n / ac standard. Specifically, the LTF and STF fields included training signals, the SIG-A and SIG-B included control information for the receiving station, and the data fields included user data corresponding to the PSDU.

This embodiment proposes an improved technique for the signal (or control information field) used for the data field of the PPDU. The signal proposed in this embodiment may be applied on a high efficiency PPDU (HE PPDU) according to the IEEE 802.11ax standard. That is, the signals to be improved in the present embodiment may be HE-SIG-A and / or HE-SIG-B included in the HE PPDU. Each of HE-SIG-A and HE-SIG-B may also be represented as SIG-A, SIG-B. However, the improved signal proposed by this embodiment is not necessarily limited to the HE-SIG-A and / or HE-SIG-B standard, and controls / control of various names including control information in a wireless communication system for transmitting user data. Applicable to data fields.

3 is a diagram illustrating an example of a HE PPDU.

The control information field proposed in this embodiment may be HE-SIG-B included in the HE PPDU as shown in FIG. 3. The HE PPDU according to FIG. 3 is an example of a PPDU for multiple users. The HE-SIG-B is included only for the multi-user, and the HE-SIG-B may be omitted in the PPDU for the single user.

As shown, a HE-PPDU for a multiple user (MU) includes a legacy-short training field (L-STF), a legacy-long training field (L-LTF), a legacy-signal (L-SIG), High efficiency-signal A (HE-SIG-A), high efficiency-signal-B (HE-SIG-B), high efficiency-short training field (HE-STF), high efficiency-long training field (HE-LTF) It may include a data field (or MAC payload) and a PE (Packet Extension) field. Each field may be transmitted during the time period shown (ie, 4 or 8 ms, etc.).

Detailed description of each field of FIG. 3 will be described later.

4 is a diagram illustrating an arrangement of resource units (RUs) used on a 20 MHz band.

As shown in FIG. 4, resource units (RUs) corresponding to different numbers of tones (ie, subcarriers) may be used to configure some fields of the HE-PPDU. For example, resources may be allocated in units of RUs shown for HE-STF, HE-LTF, and data fields.

As shown at the top of FIG. 4, 26-units (ie, units corresponding to 26 tones) may be arranged. Six tones may be used as the guard band in the leftmost band of the 20 MHz band, and five tones may be used as the guard band in the rightmost band of the 20 MHz band. In addition, seven DC tones are inserted into the center band, that is, the DC band, and there may be 26 units corresponding to each of 13 tones to the left and right of the DC band. In addition, other bands may be allocated 26-unit, 52-unit, 106-unit. Each unit can be assigned for a receiving station, ie a user.

On the other hand, the RU arrangement of FIG. 4 is utilized not only for the situation for a plurality of users (MU), but also for the situation for a single user (SU), in which case one 242-unit is shown as shown at the bottom of FIG. It is possible to use and in this case three DC tones can be inserted.

In the example of FIG. 4, various sizes of RUs, that is, 26-RU, 52-RU, 106-RU, 242-RU, etc., have been proposed. Since the specific sizes of such RUs can be expanded or increased, the present embodiment Is not limited to the specific size of each RU (ie, the number of corresponding tones).

5 is a diagram illustrating an arrangement of resource units (RUs) used on a 40 MHz band.

Just as RUs of various sizes are used in the example of FIG. 4, the example of FIG. 5 may also use 26-RU, 52-RU, 106-RU, 242-RU, 484-RU, and the like. In addition, five DC tones can be inserted at the center frequency, 12 tones are used as the guard band in the leftmost band of the 40 MHz band, and 11 tones are in the rightmost band of the 40 MHz band. This guard band can be used.

Also, as shown, the 484-RU may be used when used for a single user. Meanwhile, the specific number of RUs may be changed as in the example of FIG. 4.

6 is a diagram illustrating an arrangement of resource units (RUs) used on an 80 MHz band.

Just as RUs of various sizes are used in the example of FIGS. 4 and 5, the example of FIG. 6 may also use 26-RU, 52-RU, 106-RU, 242-RU, 484-RU, 996-RU, and the like. have. In addition, seven DC tones can be inserted in the center frequency, 12 tones are used as the guard band in the leftmost band of the 80 MHz band, and 11 tones in the rightmost band of the 80 MHz band. This guard band can be used. You can also use 26-RU with 13 tones each located to the left and right of the DC band.

Also, as shown, when used for a single user, a 996-RU may be used, in which case five DC tones may be inserted.

Meanwhile, the specific number of RUs may be changed as in the example of FIGS. 4 and 5.

7 is a diagram illustrating another example of the HE-PPDU.

7 is another example illustrating the HE-PPDU block of FIG. 3 in terms of frequency.

The illustrated L-STF 700 may include a short training orthogonal frequency division multiplexing symbol. The L-STF 700 may be used for frame detection, automatic gain control (AGC), diversity detection, and coarse frequency / time synchronization.

The L-LTF 710 may include a long training orthogonal frequency division multiplexing symbol. The L-LTF 710 may be used for fine frequency / time synchronization and channel prediction.

L-SIG 720 may be used to transmit control information. The L-SIG 720 may include information about a data rate and a data length. In addition, the L-SIG 720 may be repeatedly transmitted. That is, the L-SIG 720 may be configured in a repeated format (for example, may be referred to as an R-LSIG).

The HE-SIG-A 730 may include control information common to the receiving station.

Specifically, the HE-SIG-A 730 may include 1) a DL / UL indicator, 2) a BSS color field which is an identifier of a BSS, 3) a field indicating a remaining time of a current TXOP interval, 4) 20, Bandwidth field indicating whether 40, 80, 160, 80 + 80 MHz, 5) field indicating the MCS scheme applied to HE-SIG-B, 6) dual subcarrier modulation for HE-SIG-B for MCS ( field indicating whether the module is modulated by a dual subcarrier modulation scheme, 7) a field indicating the number of symbols used for the HE-SIG-B, and 8) a field indicating whether the HE-SIG-B is generated over the entire band. Field, 9) field indicating the number of symbols in the HE-LTF, 10) field indicating the length and CP length of the HE-LTF, 11) field indicating whether additional OFDM symbols exist for LDPC coding, 12) A field indicating control information about a packet extension (PE), and 13) a field indicating information on a CRC field of the HE-SIG-A. have. Specific fields of the HE-SIG-A may be added or omitted. In addition, some fields may be added or omitted in other environments where the HE-SIG-A is not a multi-user (MU) environment.

In addition, the HE-SIG-A 730 may be composed of two parts, HE-SIG-A1 and HE-SIG-A2. HE-SIG-A1 and HE-SIG-A2 included in the HE-SIG-A may be defined in the following format structure (field) according to the PPDU. First, the HE-SIG-A field of the HE SU PPDU may be defined as follows.

In addition, the HE-SIG-A field of the HE MU PPDU may be defined as follows.

In addition, the HE-SIG-A field of the HE TB PPDU may be defined as follows.

The HE-SIG-B 740 may be included only when it is a PPDU for a multi-user (MU) as described above. Basically, the HE-SIG-A 750 or the HE-SIG-B 760 may include resource allocation information (or virtual resource allocation information) for at least one receiving STA.

8 is a block diagram showing an example of the HE-SIG-B according to the present embodiment.

As shown, the HE-SIG-B field includes a common field at the beginning, and the common field can be encoded separately from the following field. That is, as shown in FIG. 8, the HE-SIG-B field may include a common field including common control information and a user-specific field including user-specific control information. In this case, the common field may include a corresponding CRC field and may be coded into one BCC block. Subsequent user-specific fields may be coded into one BCC block, including a "user-feature field" for two users and a CRC field corresponding thereto, as shown.

The previous field of HE-SIG-B 740 on the MU PPDU may be transmitted in duplicated form. In the case of the HE-SIG-B 740, the HE-SIG-B 740 transmitted in a part of the frequency band (for example, the fourth frequency band) is the frequency band (ie, the fourth frequency band) of the Control information for a data field and a data field of another frequency band (eg, the second frequency band) except for the corresponding frequency band may also be included. In addition, the HE-SIG-B 740 of a specific frequency band (eg, the second frequency band) duplicates the HE-SIG-B 740 of another frequency band (eg, the fourth frequency band). It can be one format. Alternatively, the HE-SIG-B 740 may be transmitted in encoded form on all transmission resources. The field after the HE-SIG-B 740 may include individual information for each receiving STA that receives the PPDU.

The HE-STF 750 may be used to improve automatic gain control estimation in a multiple input multiple output (MIMO) environment or an OFDMA environment.

The HE-LTF 760 may be used to estimate a channel in a MIMO environment or an OFDMA environment.

The size of the FFT / IFFT applied to the field after the HE-STF 750 and the HE-STF 750 may be different from the size of the FFT / IFFT applied to the field before the HE-STF 750. For example, the size of the FFT / IFFT applied to the fields after the HE-STF 750 and the HE-STF 750 may be four times larger than the size of the IFFT applied to the field before the HE-STF 750. .

For example, at least one of L-STF 700, L-LTF 710, L-SIG 720, HE-SIG-A 730, HE-SIG-B 740 on the PPDU of FIG. When a field of s is called a first field, at least one of the data field 770, the HE-STF 750, and the HE-LTF 760 may be referred to as a second field. The first field may include a field related to a legacy system, and the second field may include a field related to a HE system. In this case, the FFT (fast Fourier transform) size / inverse fast Fourier transform (IFFT) size is N times the FFT / IFFT size used in the conventional WLAN system (N is a natural number, for example, N = 1, 2, 4) can be defined. That is, an FFT / IFFT of N (= 4) times size may be applied to the second field of the HE PPDU compared to the first field of the HE PPDU. For example, 256 FFT / IFFT is applied for a bandwidth of 20 MHz, 512 FFT / IFFT is applied for a bandwidth of 40 MHz, 1024 FFT / IFFT is applied for a bandwidth of 80 MHz, and 2048 FFT for a bandwidth of 160 MHz continuous or discontinuous 160 MHz. / IFFT can be applied.

In other words, the subcarrier spacing / subcarrier spacing is 1 / N times the size of the subcarrier space used in the conventional WLAN system (N is a natural number, for example, 78.125 kHz when N = 4). Can be. That is, a subcarrier spacing of 312.5 kHz, which is a conventional subcarrier spacing, may be applied to the first field of the HE PPDU, and a subcarrier space of 78.125 kHz may be applied to the second field of the HE PPDU.

Alternatively, the IDFT / DFT period applied to each symbol of the first field may be expressed as N (= 4) times shorter than the IDFT / DFT period applied to each data symbol of the second field. . That is, the IDFT / DFT length applied to each symbol of the first field of the HE PPDU is 3.2 μs, and the IDFT / DFT length applied to each symbol of the second field of the HE PPDU is 3.2 μs * 4 (= 12.8 μs). Can be expressed as The length of an OFDM symbol may be a value obtained by adding a length of a guard interval (GI) to an IDFT / DFT length. The length of the GI can be various values such as 0.4 μs, 0.8 μs, 1.6 μs, 2.4 μs, 3.2 μs.

For convenience of description, although the frequency band used by the first field and the frequency band used by the second field are represented in FIG. 7, they may not exactly coincide with each other. For example, the main bands of the first fields L-STF, L-LTF, L-SIG, HE-SIG-A, and HE-SIG-B corresponding to the first frequency band are the second field HE-STF. , HE-LTF, Data) is the same as the main band, but in each frequency band, the interface may be inconsistent. 4 to 6, since a plurality of null subcarriers, DC tones, guard tones, etc. are inserted in the process of arranging the RU, it may be difficult to accurately match the interface.

The user, that is, the receiving station, may receive the HE-SIG-A 730 and may be instructed to receive the downlink PPDU based on the HE-SIG-A 730. In this case, the STA may perform decoding based on the changed FFT size from the field after the HE-STF 750 and the HE-STF 750. On the contrary, when the STA is not instructed to receive the downlink PPDU based on the HE-SIG-A 730, the STA may stop decoding and configure a network allocation vector (NAV). The cyclic prefix (CP) of the HE-STF 750 may have a larger size than the CP of another field, and during this CP period, the STA may perform decoding on the downlink PPDU by changing the FFT size.

Hereinafter, in the present embodiment, data (or frame) transmitted from the AP to the STA is called downlink data (or downlink frame), and data (or frame) transmitted from the STA to the AP is called uplink data (or uplink frame). Can be expressed in terms. In addition, the transmission from the AP to the STA may be expressed in terms of downlink transmission, and the transmission from the STA to the AP may be expressed in terms of uplink transmission.

In addition, each of the PHY protocol data units (PPDUs), frames, and data transmitted through downlink transmission may be expressed in terms of a downlink PPDU, a downlink frame, and downlink data. The PPDU may be a data unit including a PPDU header and a physical layer service data unit (PSDU) (or MAC protocol data unit (MPDU)). The PPDU header may include a PHY header and a PHY preamble, and the PSDU (or MPDU) may be a data unit including a frame (or an information unit of a MAC layer) or indicating a frame. The PHY header may be referred to as a physical layer convergence protocol (PLCP) header in another term, and the PHY preamble may be expressed as a PLCP preamble in another term.

In addition, each of the PPDUs, frames, and data transmitted through the uplink transmission may be represented by the term uplink PPDU, uplink frame, and uplink data.

In the WLAN system to which the present embodiment is applied, the entire bandwidth may be used for downlink transmission to one STA and uplink transmission of one STA based on single (or single) -orthogonal frequency division multiplexing (SUDM) transmission. Do. In addition, in the WLAN system to which the present embodiment is applied, the AP may perform downlink (DL) multi-user (MU) transmission based on MU MIMO (multiple input multiple output), and such transmission is DL MU MIMO transmission. It can be expressed as.

In addition, in the WLAN system according to the present embodiment, an orthogonal frequency division multiple access (OFDMA) based transmission method is preferably supported for uplink transmission and / or downlink transmission. That is, uplink / downlink communication may be performed by allocating data units (eg, RUs) corresponding to different frequency resources to the user. In more detail, in the WLAN system according to the present embodiment, the AP may perform DL MU transmission based on OFDMA, and such transmission may be expressed by the term DL MU OFDMA transmission. When DL MU OFDMA transmission is performed, the AP may transmit downlink data (or downlink frame, downlink PPDU) to each of the plurality of STAs through each of the plurality of frequency resources on the overlapped time resources. The plurality of frequency resources may be a plurality of subbands (or subchannels) or a plurality of resource units (RUs). DL MU OFDMA transmission can be used with DL MU MIMO transmission. For example, DL MU MIMO transmission based on a plurality of space-time streams (or spatial streams) on a specific subband (or subchannel) allocated for DL MU OFDMA transmission is performed. Can be.

In addition, in the WLAN system according to the present embodiment, UL MU transmission (uplink multi-user transmission) may be supported for a plurality of STAs to transmit data to the AP on the same time resource. Uplink transmission on the overlapped time resource by each of the plurality of STAs may be performed in a frequency domain or a spatial domain.

When uplink transmission by each of the plurality of STAs is performed in the frequency domain, different frequency resources may be allocated as uplink transmission resources for each of the plurality of STAs based on OFDMA. Different frequency resources may be different subbands (or subchannels) or different resource units (RUs). Each of the plurality of STAs may transmit uplink data to the AP through different frequency resources allocated thereto. The transmission method through these different frequency resources may be represented by the term UL MU OFDMA transmission method.

When uplink transmission by each of the plurality of STAs is performed on the spatial domain, different space-time streams (or spatial streams) are allocated to each of the plurality of STAs, and each of the plurality of STAs transmits uplink data through different space-time streams. Can transmit to the AP. The transmission method through these different spatial streams may be represented by the term UL MU MIMO transmission method.

The UL MU OFDMA transmission and the UL MU MIMO transmission may be performed together. For example, UL MU MIMO transmission based on a plurality of space-time streams (or spatial streams) may be performed on a specific subband (or subchannel) allocated for UL MU OFDMA transmission.

In a conventional WLAN system that did not support MU OFDMA transmission, a multi-channel allocation method was used to allocate a wider bandwidth (for example, a bandwidth exceeding 20 MHz) to one UE. The multi-channel may include a plurality of 20 MHz channels when one channel unit is 20 MHz. In the multi-channel allocation method, a primary channel rule is used to allocate a wide bandwidth to the terminal. If the primary channel rule is used, there is a constraint for allocating a wide bandwidth to the terminal. Specifically, according to the primary channel rule, when a secondary channel adjacent to the primary channel is used in an overlapped BSS (OBSS) and 'busy', the STA may use the remaining channels except the primary channel. Can't. Therefore, the STA can transmit the frame only through the primary channel, thereby being restricted to the transmission of the frame through the multi-channel. That is, the primary channel rule used for multi-channel allocation in the existing WLAN system may be a big limitation in obtaining high throughput by operating a wide bandwidth in the current WLAN environment where there are not many OBSS.

In this embodiment, to solve this problem, a wireless LAN system supporting the OFDMA technology is disclosed. That is, the above-described OFDMA technique is applicable to at least one of downlink and uplink. In addition, the above-described MU-MIMO technique may be additionally applied to at least one of downlink and uplink. When OFDMA technology is used, a plurality of terminals may be used simultaneously instead of one terminal without using a primary channel rule. Therefore, wide bandwidth operation is possible, and the efficiency of operation of radio resources can be improved.

As described above, when uplink transmission by each of a plurality of STAs (eg, non-AP STAs) is performed in the frequency domain, the AP has different frequency resources for each of the plurality of STAs based on OFDMA. It can be allocated as a link transmission resource. In addition, as described above, different frequency resources may be different subbands (or subchannels) or different resource units (RUs).

Different frequency resources for each of the plurality of STAs are indicated through a trigger frame.

9 shows an example of a trigger frame. The trigger frame of FIG. 9 allocates resources for uplink multiple-user transmission and may be transmitted from the AP. The trigger frame may consist of a MAC frame and may be included in a PPDU. For example, it may be transmitted through the PPDU shown in FIG. 3, through the legacy PPDU shown in FIG. 2, or through a PPDU specifically designed for the corresponding trigger frame. If transmitted through the PPDU of FIG. 3, the trigger frame may be included in the illustrated data field.

Each field shown in FIG. 9 may be partially omitted, and another field may be added. In addition, the length of each field may be varied as shown.

The frame control field 910 of FIG. 9 includes information about the version of the MAC protocol and other additional control information, and the duration field 920 may include time information for NAV configuration or an identifier of a terminal (eg, For example, information about AID may be included.

In addition, the RA field 930 includes address information of a receiving STA of a corresponding trigger frame and may be omitted as necessary. The TA field 940 includes address information of an STA (for example, an AP) that transmits the corresponding trigger frame, and the common information field 950 is common applied to a receiving STA that receives the corresponding trigger frame. Contains control information. For example, a field indicating the length of the L-SIG field of the uplink PPDU transmitted in response to the trigger frame, or the SIG-A field of the uplink PPDU transmitted in response to the trigger frame (that is, HE-SIG-A). Information to control the content of the field). In addition, the common control information may include information about the length of the CP of the uplink PPDU transmitted in response to the trigger frame or information about the length of the LTF field.

In addition, it is preferable to include per user information fields 960 # 1 to 960 # N corresponding to the number of receiving STAs receiving the trigger frame of FIG. 9. The individual user information field may be called an "assignment field".

In addition, the trigger frame of FIG. 9 may include a padding field 970 and a frame check sequence field 980.

Each of the per user information fields 960 # 1 to 960 # N shown in FIG. 9 preferably includes a plurality of subfields.

10 shows an example of a subfield included in a common information field. Some of the subfields of FIG. 10 may be omitted, and other subfields may be added. In addition, the length of each illustrated subfield may be modified.

The trigger type field 1010 of FIG. 10 may indicate the trigger frame variant and the encoding of the trigger frame variant. The trigger type field 1010 may be defined as follows.

The UL BW field 1020 of FIG. 10 indicates a bandwidth in the HE-SIG-A field of a HE trigger based (TB) PPDU. The UL BW field 1020 may be defined as follows.

The Guard Interval (GI) and LTF Type fields 1030 of FIG. 10 indicate the GI and HE-LTF types of the HE TB PPDU response. The GI and LTF type fields 1030 may be defined as follows.

In addition, when the GI and LTF type field 1030 has a value of 2 or 3, the MU-MIMO LTF mode field 1040 of FIG. 10 indicates an LTF mode of a UL MU-MIMO HE TB PPDU response. In this case, the MU-MIMO LTF mode field 1040 may be defined as follows.

If the trigger frame allocates an RU that occupies the entire HE TB PPDU bandwidth and the RU is assigned to one or more STAs, the MU-MIMO LTF mode field 1040 may indicate a HE single stream pilot HE-LTF mode or a HE masked HE-LTF sequence mode. It is directed to either.

If the trigger frame does not allocate an RU that occupies the entire HE TB PPDU bandwidth and the RU is not allocated to one or more STAs, the MU-MIMO LTF mode field 1040 is indicated in the HE single stream pilot HE-LTF mode. The MU-MIMO LTF mode field 1040 may be defined as follows.

11 illustrates an example of subfields included in a per user information field. Some of the subfields of FIG. 11 may be omitted, and other subfields may be added. In addition, the length of each illustrated subfield may be modified.

The User Identifier field (or AID12 field, 1110) of FIG. 11 indicates an identifier of a STA (ie, a receiving STA) to which per user information corresponds. An example of the identifier is all or the AID. It can be part of it.

In addition, the RU Allocation field 1120 may be included. That is, when the receiving STA identified by the user identifier field 1110 transmits an uplink PPDU in response to the trigger frame of FIG. 9, the corresponding uplink PPDU through the RU indicated by the RU Allocation field 1120. Send. In this case, the RU indicated by the RU Allocation field 1120 preferably indicates the RU shown in FIGS. 4, 5, and 6. The configuration of the specific RU allocation field 1120 will be described later.

The subfield of FIG. 11 may include a (UL FEC) coding type field 1130. The coding type field 1130 may indicate a coding type of an uplink PPDU transmitted in response to the trigger frame of FIG. 9. For example, when BCC coding is applied to the uplink PPDU, the coding type field 1130 is set to '1', and when LDPC coding is applied, the coding type field 1130 is set to '0'. Can be.

The subfield of FIG. 11 may include a UL MCS field 1140. The MCS field 1140 may indicate an MCS scheme applied to an uplink PPDU transmitted in response to the trigger frame of FIG. 9.

In addition, the subfield of FIG. 11 may include a trigger dependent user info field 1150. When the trigger type field 1010 of FIG. 10 indicates a basic trigger variant, the trigger dependent user information field 1150 may include an MPDU MU Spacing Factor subfield (2 bits), a TID Aggregation Limit subfield (3 bits), and a Reserved sub. Field (1 bit) and a Preferred AC subfield (2 bits).

Hereinafter, the present specification proposes an example of improving the control field included in the PPDU. The control field improved by the present specification includes a first control field including control information required for interpreting the PPDU and a second control field including control information for demodulating the data field of the PPDU. do. The first and second control fields may be various fields. For example, the first control field may be the HE-SIG-A 730 illustrated in FIG. 7, and the second control field may be the HE-SIG-B 740 illustrated in FIGS. 7 and 8. Can be.

Hereinafter, a specific example of improving the first or second control field will be described.

In the following example, a control identifier inserted into a first control field or a second control field is proposed. The size of the control identifier may vary, for example, may be implemented with 1-bit information.

The control identifier (eg, 1 bit identifier) may indicate whether 242-RU is allocated, for example when 20 MHz transmission is performed. As shown in FIGS. 4-6, RUs of various sizes may be used. These RUs can be largely divided into two types of RUs. For example, all of the RUs shown in FIGS. 4 to 6 may be divided into 26-type RUs and 242-type RUs. For example, a 26-type RU may include 26-RU, 52-RU, 106-RU, and the 242-type RU may include 242-RU, 484-RU, and larger RUs.

The control identifier (eg, 1 bit identifier) may indicate that 242-type RU has been used. That is, it may indicate that 242-RU is included or 484-RU or 996-RU is included. If the transmission frequency band to which the PPDU is transmitted is a 20 MHz band, 242-RU is a single RU corresponding to the full bandwidth of the transmission frequency band (ie, 20 MHz) band. Accordingly, the control identifier (eg, 1 bit identifier) may indicate whether a single RU corresponding to the full bandwidth of the transmission frequency band is allocated.

For example, if the transmission frequency band is a 40 MHz band, the control identifier (eg, 1 bit identifier) is assigned a single RU corresponding to the entire band (ie, 40 MHz band) of the transmission frequency band. Can be indicated. That is, it may indicate whether the 484-RU has been allocated for the transmission of 40MHz.

For example, if the transmission frequency band is an 80 MHz band, the control identifier (eg, 1 bit identifier) is assigned a single RU corresponding to the entire band (ie, 80 MHz band) of the transmission frequency band. Can be indicated. That is, it may indicate whether the 996-RU has been allocated for the transmission of 80MHz.

Various technical effects can be achieved through the control identifier (eg, 1 bit identifier).

First, when a single RU corresponding to the entire band of the transmission frequency band is allocated through the control identifier (for example, 1 bit identifier), it is possible to omit allocation information of the RU. That is, since only one RU is allocated to all bands of the transmission frequency band instead of the plurality of RUs, it is possible to omit allocation information of the RU.

It can also be used as signaling for full-band multi-user full bandwidth MU-MIMO. For example, when a single RU is allocated over the full bandwidth of the transmission frequency band, multiple users may be allocated to the single RU. That is, signals for each user are not spatially and spatially distinct, but other techniques (eg, spatial multiplexing) may be used to multiplex the signals for multiple users in the same single RU. Accordingly, the control identifier (eg, 1 bit identifier) may also be used to indicate whether to use the full-band multi-user MIMO as described above.

The common field included in the second control field HE-SIG-B 740 may include an RU allocation subfield. According to the PPDU bandwidth, the common field may include a plurality of RU allocation subfields (including N RU allocation subfields). The format of the common field may be defined as follows.

The RU allocation subfield included in the common field of the HE-SIG-B is configured with 8 bits, and can be indicated as follows for a 20 MHz PPDU bandwidth. The RU allocation to be used in the data portion in the frequency domain indicates the size of the RU and the placement of the RU in the frequency domain as an index. The mapping of the 8-bit RU allocation subfield for the RU allocation and the number of users per RU may be defined as follows.

The user-specific field included in the second control field HE-SIG-B 740 may include a user field, a CRC field, and a tail field. The format of the user-specific field may be defined as follows.

In addition, the user-specific field of the HE-SIG-B is composed of a plurality of user fields. Multiple user fields are located after the common fields of the HE-SIG-B. The location of the RU assignment subfield of the common field and the user field of the user-specific field together identify the RU used to transmit data of the STA. Multiple RUs designated as a single STA are not allowed in the user-specific field. Thus, the signaling that enables the STA to decode its data is carried in only one user field.

As an example, assume that the RU allocation subfield is indicated by 8 bits of 01000010 to indicate that one 26-tone RU is followed by five 26-tone RUs, and that the 106-tone RU includes three user fields. . At this time, the 106-tone RU may support multiplexing of three users. The eight user fields contained in the user-specific fields are mapped to six RUs, the first three user fields are assigned MU-MIMO in the first 106-tone RU, and the remaining five user fields are five 26- It may indicate that it is allocated to each of the tone RU.

The user field included in the user-specific field of the HE-SIG-B may be defined as follows. First, the user field for non-MU-MIMO allocation is as follows.

User fields for MU-MIMO allocation are as follows:

12 is a diagram illustrating an example of a HE TB PPDU. The PPDU of FIG. 12 indicates an uplink PPDU transmitted in response to the trigger frame of FIG. 9. At least one STA receiving the trigger frame from the AP may check the common information field and the individual user information field of the trigger frame and simultaneously transmit the HE TB PPDU with the other STA that received the trigger frame.

As shown, the PPDU of FIG. 12 includes various fields, each field corresponding to the fields shown in FIGS. 2, 3, and 7. Meanwhile, as shown, the HE TB PPDU (or uplink PPDU) of FIG. 12 may include only the HE-SIG-A field and not the HE-SIG-B field.

One. CSMA Carrier sense multiple access / collision avoidance (CA)

In IEEE 802.11, communication is fundamentally different from wired channel environments because the communication occurs on a shared wireless medium. For example, in a wired channel environment, communication was possible based on carrier sense multiple access / collision detection (CSMA / CD). For example, once a signal is transmitted in Tx, the channel environment does not change so much that Rx does not suffer significant signal attenuation. At this time, if two or more signals collided, detection was possible. This is because the power sensed at the Rx stage is momentarily larger than the power transmitted at Tx. However, in a wireless channel environment, various factors (e.g., attenuation of the signal may be large or may experience deep fading momentarily depending on the distance) affect the channel. Tx cannot accurately sense carrier. Therefore, 802.11 introduced a distributed coordination function (DCF), a carrier sense multiple access / collision avoidance (CSMA / CA) mechanism. This performs a clear channel assessment (CCA) that senses the medium for a certain duration (eg DIFS: DCF inter-frame space) before STAs with data to transmit. At this time, if the medium is idle, the STA can transmit using the medium. However, if the medium is busy, assuming that several STAs are already waiting to use the medium, data can be transmitted after waiting for an additional random backoff period in addition to DIFS. In this case, the random backoff period allows collision avoidance, because assuming that there are several STAs for transmitting data, each STA has a different backoff interval value and thus different transmission time. to be. When one STA starts transmission, the other STAs cannot use the medium.

The following briefly describes the random backoff time and procedure. When a certain medium changes from busy to idle, several STAs start preparing to send data. At this time, STAs that want to transmit data to minimize collision select random backoff counts and wait for the slot time. The random backoff count is a pseudo-random integer value that selects one of the uniformly distributed values in the [0 CW] range. CW stands for contention window. The CW parameter takes the CWmin value as the initial value, but if the transmission fails, the value is doubled. For example, if an ACK response is not received for a transmitted data frame, a collision can be considered. If the CW value has a CWmax value, the CWmax value is maintained until the data transmission is successful, and the data transfer succeeds and is reset to the CWmin value. At this time, CW, CWmin, CWmax is preferable to maintain 2 ⁿ -1 for convenience of implementation and operation. On the other hand, when the random backoff procedure starts, the STA selects a random backoff count in the [0 CW] range and continuously monitors the medium while the backoff slot counts down. In the meantime, if the medium is busy, it stops counting down and when the medium becomes idle again, it resumes counting down the remaining backoff slots.

2. PHY  procedure

The PHY transmit / receive procedure in Wi-Fi may have a different packet configuration method, but is as follows. It looks like this: For simplicity, we will use only 11n and 11ax as examples, but 11g / ac follows a similar procedure.

That is, the PHY transmit procedure converts the MAC protocol data unit (MPDU) or A-MPDU (Aggregate MPDU) from the MAC stage into a single PSDU (PHY service data unit) at the PHY stage, and preamble and tail bits and padding bits (if necessary). Is transmitted by inserting the

The PHY receive procedure usually looks like this: When energy detection and preamble detection (L / HT / VHT / HE-preamble detection for each Wifi version), the information on the PSDU configuration is obtained from the PHY header (L / HT / VHT / HE-SIG) to read the MAC header and data Read

3. Multi-band (or Multi-link) aggregation

WLAN 802.11 system considers the transmission of increased stream by using wider band or using more antennas than 11ax to increase peak throughput. It also considers how to aggregate and use various bands.

In the present specification, in a situation in which wide bandwidth and multi-band (or multi-link) aggregation are considered, a method of simultaneously transmitting data of HE STAs and EHT STAs using one same MU PPDU is proposed.

13 shows a number of channels allocated in the 5 GHz band.

Hereinafter, the "band" may include, for example, the 2.4 GHz, 5 GHz, and 6 GHz bands. For example, in the 11n standard, the 2,4 GHz band and the 5 GHz band were supported, and in the 11ax standard, the 6 GHz band was also supported. For example, in the 5 GHz band, a plurality of channels as shown in FIG. 13 may be defined. .

In the WLAN system to which the technical features of the present disclosure are applied, multi-band may be supported. That is, the transmitting STA transmits the PPDU on any channel (eg, 20/40/80/80 + 80/160 MHz, etc.) on the first band (eg, 5 GHz), for example, It is possible to transmit a PPDU on any channel (eg 20/40/80/80 + 80/160/240/320 MHz, etc.) on the second band (eg 6 GHz). (In this specification, a 240 MHz channel may be a continuous 240 MHz channel or a combination of discontinuous 80/160 MHz channels. Also, a 320 MHz channel may be a continuous 320 MHz channel or a discontinuous 80/160 MHz channel. For example, in this document, a 240 MHz channel may mean a continuous 240 MHz channel, an 80 + 80 + 80 MHz channel, or an 80 + 160 MHz channel).

In addition, the multi-band described in this document can be interpreted in various ways. For example, the transmitting STA sets any one of the 20/40/80/80 + 80/160/240/320 MHz channels on the 6 GHz band as the first band and another 20/40/80 on the 6 GHz band. Any one of the / 80 + 80/160/240/320 MHz channels may be set as the second band, and multi-band transmission (that is, transmission supporting both the first band and the second band at the same time) may be performed. For example, the transmitting STA may transmit the PPDU simultaneously on the first band and the second band or may transmit on only one band at a specific time.

At least one of the primary 20 MHz and the secondary 20/40/80/160 MHz channels described below may be transmitted in the first band, and the remaining channels may be transmitted in the second band. Alternatively, all channels may be transmitted in the same one band.

The term "band" herein may be replaced with "link".

The following describes a control signaling method for multi-band aggregation. The control signaling method may employ a fast session transfer (FST) setting method, and the FST setting protocol will be described below.

The FST setting protocol consists of four states and rules about how to move from one state to the next. The four states are Initial, Setup Completed, Transition Done, and Transition Confirmed. In the Initial state, the FST session runs on one or two bands / channels. In the Setup Complete state, the initiator and responder are ready to change the currently operating band / channel (s). FST sessions may be delivered in whole or in part to other bands / channels. The Transition Done state allows the initiator and responder to operate in different bands / channels when the LLT (Link Loss Timeout) is 0. Both the initiator and the responder must successfully communicate on the new band / channel to reach the Transition Confirmed state. A state transition diagram of the FST setting protocol is shown in FIG.

14 shows four states of the FST setting protocol.

15 shows a procedure of an FST setting protocol.

FIG. 15 shows the procedure of the FST setting protocol for driving the state machine shown in FIG. 15 is an example of a basic procedure and does not cover all possible uses of the protocol. In FIG. 15, MAC Layer Management Entity (MLME) 1 and MLME 2 represent any two MLMEs of a multi-band capable device according to the reference model described in the reference model for multi-band operation. As will be described later, the exchange of the FST Setup Request and FST Setup Response frames is repeated as necessary until the FST initiator and the FST responder successfully move to the Setup Completed state. 15 illustrates the operation of the procedure of the FST setting protocol.

In order to establish an FST session in the Initial state and deliver it to the Setup Completed state of the FST configuration protocol, the initiator and the responder must exchange the FST Setup Request and FST Setup Response frames. An FST session exists in the Setup Completed state, Transition Done state, or Transition Confirmed state. In the Initial state and the Setup Completed state, the old band / channel represents the frequency band / channel to which the FST session is to be delivered, and the new band / channel represents the frequency band channel to which the FST session is to be delivered. In the Transition Done state, the new band / channel represents the frequency band / channel through which the FST Ack Request and FST Ack Response frames are transmitted, and the old band / channel represents the frequency band / channel through which the FST session is delivered.

If the Responder accepts the FST Setup Request, the Status Code field is set to SUCCESS and the Status Code is set to REJECTED_WITH_SUGGESTED_CHANGES so that one or more parameters in the FST installation request frame are invalid and should suggest alternative parameters. In addition, the responder sets the Status Code field to PENDING_ADMITTING_FST_SESSION or PENDING_GAP_IN_BA_WINDOW to indicate that the FST setting request is pending, and sets the Status Code field to REQUEST_DECLINED to reject the FST Setup Request frame.

The responder, which is an enabling STA, indicates that the FST Setup Request frame has been rejected because it was initialized by the subordinate STA requesting the switch to the frequency band to which the DSE procedure is applied by setting the status code to REJECT_DSE_BAND. In this case, when the responder is an enabling STA for the subordinate STA, the responder may indicate a period in the TU before starting the FST setup with the subordinate STA by including a Timeout Interval element in the FST Setup Response frame. The Timeout Interval Type field in the Timeout Interval element shall be set to 4. The Responder may use the parameters in the FST Setup Request frame received from the subordinate STA to initiate FST setup with the initiator.

Subordinate STAs and non-capable respondents should reject all received FST Setup Request frames for switching to frequency bands subject to the DSE procedure, except when the transmitter of the FST Setup Request frame is the enabling STA of the subordinate STA. .

4. Examples applicable to the present invention

16 shows an example of multi-band aggregation using a 2.4 GHz band and a 5 GHz band.

Referring to FIG. 16, an AP and an STA may transmit and receive data by aggregation of 2.4 GHz and 5 GHz bands. Such multi-band aggregation can be aggregated in any band from 1 to 7.125 GHz as well as 2.4 / 5 GHz, and can be aggregated using multiple RFs in the same band (eg, 5 GHz). Thus, by using multi-band aggregation or multiple RFs in the same band, there is an opportunity to use not only the bandwidth used by 802.11 but also the bandwidth of 160 MHz or more (eg 320 MHz).

In the structure as shown in FIG. 16, in order to perform contention as in the prior art, a backoff is performed for one 20 MHz primary channel (Primary 20 or P20) determined regardless of multi-bands, and at the moment when transmission is possible in P20 (backoff count = 0) Before that, IDLE / BUSY of the secondary channel during PIFS (or DIFS) is determined to determine the transmission bandwidth.

However, as a fairly wide bandwidth of 160 MHz or more is available, secondary channels having a wide bandwidth such as 160 MHz secondary channel (Secondary 160), 320 MHz secondary channel (Secondary 320), and the like may exist. In particular, in dense environments, the availability of these secondary channels is highly likely to be BUSY. In addition, when CCA is performed on the secondary channel according to the existing CCA rule (Primary 20-> Secondary 20-> Secondary 40…), a band aggregation combination (for example, 120 MHz (40) is used instead of the 20/40/80/160/320 MHz unit size. +80), 240MHz (80 + 160), etc., you can not use the existing rule.

Therefore, in this specification, in order to solve the problems described above, a method of contention is provided by placing a primary channel for each band (or RF).

5. Proposed Example

17 illustrates an example in which a primary channel exists in each band (or RF) when multi-band aggregation is performed.

When aggregation of 160 MHz of 5 GHz and 160 MHz of 6 GHz as shown in FIG. 17, P20 exists in each band, and P20 may exist regardless of the bandwidth size applied to each band (or RF) (except 20 MHz). .

Basically, the Wi-Fi system performs contention based on one P20.In the EDCA function (EDCAF), a backoff is randomly selected between the contention window (CW) value and 0 ~ CW for contention for each access category (AC). count (BC) is required. Therefore, when multiple primary channels exist, that is, when primary channels exist in each band (or RF), a new contention rule is required for frame transmission, and CW and BC can be applied as follows.

A. Common CW for all P20s, separate BC for each P20

In case of method A, the BC decrement rule for each primary channel can be flexibly applied as before, but more processing overhead is required. In addition, the CW adjustment method for the transmission success of each band is additionally required.

B. Apply common CW and BC for all P20

In case of B method, one CW and BC can be maintained regardless of the number of primary channels, but a new BC decrement rule is required according to the channel state of each P20.

C. Have a separate CW for each P20 and apply a separate BC for each P20

In the case of the C method, the BC decrement rule for each primary channel and the CW adjustment method according to the transmission success can be flexibly applied as in the conventional method, but more processing overhead is required.

If the B method is applied, the BC decrement rule can be applied as follows.

1) Decrease BC value when all P20 channel status is IDLE

Viewing all P20s in an integrated way reduces the probability of collision, but can increase transmission latency.

2) Decrease BC value when at least one channel state of all P20s is IDLE

-> 1) The transmission latency can be reduced compared to the method, but the collision probability can be increased because other P20s ignore the BUSY case.

FIG. 18 shows an example of applying the BC decrement rule of the method B-2) when the 2.4 GHz, 5 GHz, and 6 GHz bands are aggregated.

In this example, to show a simple process, the CCA during BUSY and IFS is omitted and only the process of decreasing the backoff count is shown. In FIG. 16, a common BC value is initially selected as 3, and BC is decreased according to the channel state of each P20. In Slot 1, Slot 3, and Slot 4, one or more P20s are IDLE, reducing BC, and in Slot 2, they are all BUSY, so we maintain BC.

This specification deals with a method for efficiently applying enhanced distributed channel access (EDCA) when using multi-band (or multi-link) in a WLAN system. EDCA is an operation mode of a hybrid coordination function (HCF) based on competition. The HCF is capable of transmitting Quality of Service (QoS) data during a contention period controlled by a DCF (Distributed Coordination Function) and a non contention period controlled by a Point Coordination Function (PCF). QoS is implemented through the HCF method to improve the DCF and PCF methods.

19 shows an example of a BSS that simultaneously supports multi-band using band 1 and band 2.

Referring to FIG. 19, band 1 (Band 1) may be 2.4 GHz, and band 2 (Band 2) may be 5 GHz. In addition, as shown in FIG. 19, the AP and the STA may operate while using both band 1 and band 2 simultaneously or using only one. 19 is only one example, the multi-band simultaneously supported by the AP or the STA may be two or more, and may extend to bands other than the 2.4 GHz and 5 GHz bands (for example, the 6 GHz band). The expansion method is performed in the same manner as in the following embodiment.

5.1. The BSS configuration is configured such that terminals having various band capacities can operate in one BSS.

AP has the ability to support multi-band at the same time.

-STA1 has the ability to support multi-band at the same time as the AP.

STA2 may operate in band 1 with a single band capacity.

STA3 may operate in band 2 with a single band capability.

5.2. One BSS primary channel exists for each band, and therefore, an AP and an STA that support multi-band have a multi-primary channel. A STA supporting a single band has one primary channel.

-AP and STA having a multi-primary channel performs full carrier sensing (ie, physical CS and virtual CS) through a primary channel defined in each band.

An STA operating using a single primary channel performs full carrier sensing through a primary channel within a single band.

5.3. The operation of EDCA in BSS supporting multi-primary channel is as follows.

20 shows an example of segmenting EDCA traffic by band.

-In case of AP or STA that supports multi-band, when traffic comes down from the upper layer before transmitting data, the busy degree is determined by determining the traffic load of each band or channel status by band. EDCA traffic can be divided into bands for transmission through the lowest band.

Therefore, EDCA traffic configured in each band operates with one BC (backoff counter value) and contention window (CW) for each access category (AC).

-Each traffic can be transmitted only through the set band. If the primary channel of the set band is idle, it can be transmitted through multi-band aggregation if the channel state of another band not set is idle during PIFS.

In this method, the complexity is reduced because it operates with one BC value and CW in applying the EDCA channel access method to the multi-primary channel environment, and judges the load of traffic per band or the channel status per band. In this way, the offloading effect is excellent because the traffic is distributed by band.

21 shows another example of segmenting EDCA traffic by band.

-In case of an AP or STA that supports multi-band, when traffic comes down from the upper layer before transmitting data, carrier sensing is performed using multi-band simultaneously, and traffic is first transmitted through a band to which an idle primary channel belongs. Will be sent.

Therefore, each EDCA traffic operates with BC value and CW per band. First, if there is a BC value that comes with zero, the other BC value is considered 0 or discarded. Referring to FIG. 21, when BC 1 of band 1 becomes 0, EDCA traffic 6 having the highest priority may be transmitted through band 1, so that EDCA traffic 6 of band 2 does not need to be transmitted. have.

-This method increases complexity because it works with BC value and CW as the number of bands to support EDCA channel access method in multi-primary channel environment, but transmits data through idle band as soon as possible. This is an excellent method for improving channel utilization.

5.4. STAs operating in a multi-primary channel within one BSS and configuring the BSS have various band capabilities as shown in FIG. 19 as shown in the foregoing example, and thus, flexible DL / UL data transmission / reception is possible. In addition, since the AP has a multi-band capacity, multi-band aggregation may be performed when transmitting and receiving data with the UE having the multi-band capability.

22 illustrates multi-band aggregation and flexible DL / UL scheme.

Multi-band aggregation

The AP having the multi-band capability can transmit data to STA1 having the multi-band capability through two idle bands according to the EDCA scheme described above.

-Flexible DL / UL

The AP may transmit data to the STA 2 operating in band 1 while having a single band capacity if idle through carrier sensing for a primary channel in band 1.

At the same time, STA 3 having a single band capability and operating in band 2 may transmit data to the AP if idle through carrier sensing for a primary channel in band 2.

AP has multi-band capability and supports multi-primary channel at the same time, so full carrier sensing of primary channel in each band is possible and thus flexible DL / UL transmission is possible.

5.5 How to apply EDCA channel access

A. Use existing access categories

An AP or STA with multi-band capability has two BCs for each AC when performing the EDCA. BC 1 is used to send data in band 1 and BC 2 is used to send data in band 2.

B. In each AC buffer, traffic has priority according to user priority (UP), and the priority of the traffic unit through a field or element including a traffic identifier (TID) subfield. Can be explicitly stated. In addition, even the same traffic can be divided into traffic with priority and traffic without priority.

FIG. 23 illustrates a relationship between AC and BC for each AC used when a terminal having multi-band capability transmits data.

As illustrated in FIG. 23, there are traffic 1 / traffic 2 / traffic 3 waiting to be transmitted to AC_VO as illustrated in FIG. 23. And, the priority of the traffic is traffic 1, traffic 2, traffic 3 in order. That is, there is a priority of the traffic, and whether there is a priority for each traffic.

Traffic 1 to 3 of FIG. 23 assumes the BSS environment of FIG. 19.

In Case a of FIG. 19, traffic 1 is traffic for the AP to transmit to STA1.

In Case b of FIG. 19, traffic 2 is traffic for the AP to transmit to STA2.

In Case c of FIG. 19, traffic 3 is traffic for the AP to transmit to STA3.

5.6. EDCA channel access application embodiment

24 illustrates an example in which EDCAs in various cases are performed in a BSS that simultaneously supports multi-band using band 1 and band 2.

EDCA channel access method that can be applied when an AP with multi-band capability transmits data to a STA having multi-band capability (STA 1 of FIG. 24) or a STA having only single-band capability ( STA 2, 3 of FIG. 24) Suggest. The same EDCA channel access method proposed herein applies even when an STA having multi-band capability transmits data to an AP having multi-band capability or an AP having only a single band capability.

When an AP with multi-band capability transmits data to STAs having various band capabilities and operating bands as shown in the above figure, we propose a channel access method by dividing into case a, case b, and case c. . The scenario as shown in FIG. 24 may be performed in one BSS or may be performed in multiple BSSs.

A. Case a

25 illustrates an example in which EDCA between an AP having a multi-band capability and an STA is performed.

EDCA traffic 1 may be sent from the AP (with multiband capability) to STA1 (with multiband capability) (or EDCA traffic 1 may be received from STA1).

Referring to FIG. 25, when the AP determines that the band 1 and the band 2 are idle by performing carrier sensing simultaneously, the AP decreases the value of BC 1 or BC 2. First, the AP transmits data to the STA through the band corresponding to BC which becomes 0. First, even during data transmission through a band in which the BC value becomes 0, the AP may perform CS (carrier sensing or channel sensing) through other bands. If the CS determines that it is idle, the AP can reduce the BC value and, when it reaches 0, can transmit data through other bands.

In addition, the AP can operate in the RX mode through the other band because full carrier sensing can be performed in another band even while data is transmitted through the band where the BC value becomes zero first. Therefore, the AP may operate in the TX mode and the RX mode for each band at the same time (ie, may operate in full duplex radio (FDR)).

B. Case b

FIG. 26 illustrates an example in which EDCA is performed between an AP having a multi band capability and an STA having a single band capability.

EDCA traffic 2 may be sent from the AP (with multiband capability) to STA2 (with single band capability (band 1)) (or EDCA traffic 2 may be received from STA2).

Referring to FIG. 26, Method 1 and Method 2 may be proposed as follows.

Method 1) At the same time, carrier sensing is performed through band 1 and band 2 separately, and when band 1 is idle, the value of BC 1 is decreased, and when band 2 is idle, the value of BC 2 is decreased.

1-1) When BC 1 becomes 0, traffic 2 is transmitted.

1-2) When the value of BC 2 becomes 0 before the value of BC 1, the following embodiments may be performed.

If traffic 2 is traffic with the above-mentioned priority, then traffic 2 must be sent before traffic 3 (because traffic 2 is higher than traffic 3). However, since traffic 2 cannot be sent to band 2, the value of BC 2 is randomly extracted again. This process is repeated until BC 1 is zero.

-Or, if traffic 2 is traffic having no priorities as described above, first, traffic 3 is transmitted before traffic 2 through band 2 where the BC value becomes zero. That is, traffic 3 may first be transmitted to STA 3 through band 2. If the AC_VO buffer has no traffic to transmit through band 2, such as traffic 3, as shown in the example above, the BC in band 2 waits until there is traffic that can transmit to band 2 and enters the buffer and starts a new BC procedure. .

-Or, transmit traffic 3 before traffic 2 through band 2 where the BC value becomes zero. That is, traffic 3 may first be transmitted to STA 3 through band 2. In this case, when the traffic 3 is sent for the fairness of the UEs using only the band 1, the traffic 3 is transmitted using only the band 2 without aggregation of the band 1 and the band 2 even when the band 1 is idle. Thus, the transmission opportunities of the terminal using only band 1 can be balanced with the transmission opportunities of the terminal using band 1 and band 2 simultaneously.

Method 2) Because traffic 2 is traffic that can only be sent through band 1, it decreases BC 1 only through band 1 and does not reduce BC 2.

Regardless of whether the traffic 2 has priority or not, if the value of BC 1 becomes 0, traffic 2 is transmitted. (Traffic 2 is traffic transmitted to STA 2 operating only in band 1, so it is not necessary to use band 2 to transmit traffic 2.)

C. Case c

FIG. 27 shows another example in which EDCA is performed between an AP having a multi band capability and an STA having a single band capability.

EDCA traffic 3 may be sent from the AP (with multiband capability) to STA 3 (with single band capability (band 2)) (or EDCA traffic 3 may be received from STA 3).

Referring to FIG. 27, Method 1 and Method 2 may be proposed as follows.

Method 1) At the same time, carrier sensing is performed through band 1 and band 2 separately, and when band 1 is idle, the value of BC 1 is decreased, and when band 2 is idle, the value of BC 2 is decreased.

1-1) When BC 2 reaches 0, traffic 3 is transmitted.

1-2) When the value of BC 1 becomes 0 before the value of BC 2, the following embodiments may be performed.

If traffic 3 is the traffic with the above-mentioned priority, since traffic 3 has a lower priority than traffic 2, it first transmits traffic 2 before traffic 3 on band 1, where the BC value becomes zero. If the AC_VO buffer has no traffic to transmit through band 1, such as traffic 2, as shown in the example above, the BC in band 1 waits until there is traffic that can transmit to band 1 in the buffer and then starts a new BC procedure. .

-Or, if traffic 3 is traffic having no priority as described above, first, traffic 2 is transmitted before traffic 3 through band 1 where the BC value becomes 0. If the AC_VO buffer has no traffic to transmit through band 1, such as traffic 2, as shown in the example above, the BC in band 1 waits until there is traffic that can be sent to band 1 in the buffer and then starts a new BC procedure. .

-Or, transmit traffic 2 before traffic 3 through band 1 where the BC value becomes zero. That is, traffic 2 may first be transmitted to STA 2 through band 1. At this time, when the traffic 2 is sent for the fairness of the UEs using only the band 2, the traffic 2 is transmitted using only the band 1 without aggregation of the band 1 and the band 2 even when the band 2 is idle. Thus, the transmission opportunities of the terminal using only band 2 can be balanced with the transmission opportunities of the terminal using band 1 and band 2 simultaneously.

Method 2) Because traffic 3 is traffic that can only be sent through band 2, it decreases BC 2 only through band 2 and does not decrease BC 1.

Regardless of whether the priority of traffic 3 is prior, when the value of BC 2 becomes 0, traffic 3 is transmitted. (Traffic 3 is traffic sent to STA 3 operating only in band 2, so it is not necessary to use band 1 to transmit traffic 3).

5.7. EDCA channel access method 2 (define new AC)

When the terminal supporting the multi-band is applied to the EDCA channel access, a new access category (AC) may be defined by newly defining an EDCA parameter set element considering multi-band operation.

28 shows an example of AC defined in a multi-band environment.

28 is an example of a new AC classification for VO (voice) among four ACs. This classification applies equally to video (VI), best effort (BE), and background (BK).

-Traffic 1 is EDCA in AC_multi-band VO because the traffic is transmitted to UE with multi-band capability.

-Traffic 2 is EDCA in AC_band 1 VO because the traffic 2 is traffic to be transmitted to a terminal operating in band 1 among terminals having a single band capability.

-Traffic 3 is EDCA in AC_band 2 VO because it is traffic to be transmitted to a terminal operating in band 2 among terminals with single band capability.

At the same time and separately, carrier sensing is performed through band 1 and band 2, when band 1 is idle, the value of BC 1 is decreased, and when band 2 is idle, the value of BC 2 is decreased, and then the band where the BC value becomes 0 is selected. Transmit the corresponding traffic through.

Hereinafter, the above-described embodiment will be described with reference to FIGS. 13 to 28.

29 is a flowchart illustrating a procedure of transmitting traffic according to the present embodiment.

29 may be performed in a network environment in which a next generation WLAN system is supported. The next generation WLAN system is a WLAN system that improves the 802.11ax system and may satisfy backward compatibility with the 802.11ax system. The next generation WLAN system may correspond to an Extreme High Throughput (ETH) WLAN system or an 802.11be WLAN system.

This embodiment proposes a method for performing band-specific (or link) EDCA in a multi-band (or multi-link) environment in a next-generation wireless LAN system such as EHT.

An example of FIG. 29 is performed in an AP, and the receiving apparatus of FIG. 29 may correspond to an STA that supports an Extremely High Throughput (ETH) wireless LAN system.

In step S2910, the access point (AP) generates the first to third traffic.

In step S2920, the AP performs carrier sensing on a multi-band.

In step S2930, the AP transmits the first traffic to the first STA through the multi-band based on a result of the carrier sensing.

The multi band is aggregated with a first band and a second band. The first band includes a first primary channel and the second band includes a second primary channel.

If the multiple bands are combined into only two bands, the first band may be a 2.4 GHz or 5 GHz band, and the second band may be a 6 GHz band. If the third band is further combined with the third band, the first band may be a 2.4 GHz band, the second band may be a 5 GHz band, and the third band may be a 6 GHz band. However, the above-described configuration of the band is just one example, and the WLAN system may support various numbers of bands and channels.

The carrier sensing may be performed separately while simultaneously performing the first and second bands. In detail, the carrier sensing is performed based on a first backoff count (BC) value for the first band. The carrier sensing is performed based on a second BC value for the second band.

In addition, the carrier sensing may include physical carrier sensing and virtual carrier sensing. The physical carrier sensing may correspond to carrier sensing such as clear channel assessment (CCA), and the virtual carrier sensing may correspond to carrier sensing such as NAV (Network Allocation Vector) configuration. The physical carrier sensing and the virtual carrier sensing may be performed on the first and second primary channels.

In this case, the AP and the first STA support the multi-band.

When the first BC value becomes 0, the first traffic may be transmitted through the first band. When the second BC value becomes 0, the second traffic may be transmitted through the second band. That is, the AP may first transmit data (or traffic) to the STA through the band for the BC value which becomes 0. For example, if the first BC value becomes 0 first, the AP may perform carrier sensing for the second band even while transmitting the first traffic to the first STA. When the channel of the second band is idle, the second BC value is decreased, and when the second BC value is 0, the AP can transmit the second traffic to the first STA through the second band. have.

Carrier sensing for the first and second bands may correspond to carrier sensing for the first and second primary channels. Hereinafter, an embodiment in which the first traffic is transmitted based on carrier sensing in the first and second primary channels.

When it is determined that the first primary channel is idle, the first BC value may decrease. If it is determined that the second primary channel is idle, the second BC value may decrease. When the first and second BC values become zero, the first traffic may be transmitted through the first and second primary channels.

In addition, the AP may transmit traffic by performing carrier sensing to an STA that supports only a single band.

The AP may transmit the second traffic to a second STA based on a result of the carrier sensing. In addition, the AP may transmit the third traffic to a third STA based on a result of the carrier sensing.

When the first BC value becomes 0, the second traffic may be transmitted to the second STA through the first band. When the second BC value becomes 0, the third traffic may be transmitted to the third STA through the second band.

In this case, the second STA may support only the first band, and the third STA may support only the second band.

According to the embodiment described above, when the first BC value becomes 0, the AP may transmit the second traffic to the second STA through the first band. However, when performing the EDCA between the AP and the second STA, there may be a case where the second BC value becomes zero before the first BC value. Hereinafter, an EDCA method between the AP and the second STA will be described in consideration of the priority of the second traffic with other traffic.

If the second BC value becomes zero before the first BC value, if the second traffic has a higher priority than the third traffic, the first BC value is zero until the first BC value becomes zero. The 2 BC value can be reset. That is, the second traffic should be transmitted before the third traffic, but since the first BC value is not zero, the second traffic cannot be sent yet. In addition, the second traffic may not be transmitted to the second STA through the second band. Accordingly, the AP may randomly extract the second BC value again until the first BC value becomes zero.

When the second BC value becomes zero before the first BC value, if the second traffic has no priority with the third traffic, the third traffic may be transmitted before the second traffic. In other words, if there is no priority of traffic, it should be able to transmit any traffic first if it is ready to transmit regardless of traffic order. Accordingly, the AP may transmit the third traffic to the third STA before the second traffic. However, for fairness with terminals such as a second STA using only the first band, when the third traffic is sent, the first band and the second band are not aggregated even when the first band is idle. And transmits the third traffic using only the second band. Accordingly, the transmission opportunity of the STA using only the first band can be balanced with the transmission opportunity of the STA using the first and second bands at the same time.

The first to third traffic may be buffered for each access category (AC). The AC may include AC_VO (Voice), AC_VI (Video), AC_BE (Best Effort), and AC_BK (Background) as previously defined. For each AC the BC value can be set per band.

In addition, a new AC may be defined as follows by newly defining an EDCA Parameter Set element considering multi-band (or multi-link) operation. The first traffic may be buffered in AC for the multiple bands. The second traffic may be buffered in AC for the first band. The third traffic may be buffered in AC for the second band. The BC value for the AC for the multi-band can be set for each band. A first BC value may be set for AC for the first band. A second BC value may be set for the AC for the second band.

Hereinafter, a signaling scheme for multi-band aggregation will be described. In the present embodiment, it has been described as receiving configuration information for multiple bands, and signaling may be performed by using an FST configuration scheme.

The transmitter may transmit the multi-band setup request frame to the receiver. The transmitter may receive a multi-band setup response frame from the receiver.

The transmitter may transmit a multi-band Ack request frame to the receiver. The transmitter may receive a multi-band Ack response frame from the receiver.

The transmitter may include a first station management entity (SME), a first MAC layer management entity (MLME), and a second MLME. The receiver may include a second SME, a third MLME, and a fourth MLME.

The first MLME and the third MLME may be an entity supporting the first band, and the second MLME and the fourth MLME may be an entity supporting the second band.

The multi-band configuration request frame and the multi-band configuration response frame may be transmitted and received between the first MLME and the third MLME. The multi-band Ack request frame and the multi-band Ack response frame may be transmitted and received between the second MLME and the fourth MLME.

The first and second SMEs may generate primitives including multi-band parameters. The multiband parameter may include a channel number, an operating class, and a band identifier designated in the multiband. The primitive may be delivered to the first to fourth MLME.

When the multi-band method employs the FST setting method, the multi-band method includes four states, and includes rules on how to move from one state to the next state. The four states are Initial, Setup Completed, Transition Done, and Transition Confirmed.

In the Initial state, the transmitter and the receiver communicate in the old band / channel. At this time, when the FST setting request frame and the FST setting response frame are transmitted / received between the transmitter and the receiver, the apparatus moves to the Setup Complete state, and the transmitter and the receiver are ready to change the currently operating band / channel (s). do. FST sessions may be delivered in whole or in part to other bands / channels.

When the value of the LLT included in the FST setup request frame is 0, the LLT moves from the Setup Complete state to the Transition Done state, and enables the transmitter and the receiver to operate in different bands / channels.

Both the transmitter and receiver must successfully communicate on the new band / channel to reach the Transition Confirmed state. At this time, when the FST Ack request frame and the FST Ack response frame are transmitted / received between the transmitter and the receiver, the UE moves to the Transition Confirmed state, and the transmitter and the receiver form a complete connection in a new band / channel.

30 is a flowchart illustrating a procedure of receiving traffic according to the present embodiment.

30 may be performed in a network environment in which a next generation WLAN system is supported. The next generation WLAN system is a WLAN system that improves the 802.11ax system and may satisfy backward compatibility with the 802.11ax system. The next generation WLAN system may correspond to an Extreme High Throughput (ETH) WLAN system or an 802.11be WLAN system.

This embodiment proposes a method for performing band-specific (or link) EDCA in a multi-band (or multi-link) environment in a next-generation wireless LAN system such as EHT.

An example of FIG. 30 may be performed by a receiving apparatus and correspond to an STA that supports an Extremely High Throughput (ETH) wireless LAN system. The transmitter of FIG. 30 may correspond to an AP.

In step S3010, a station (STA) receives first to third traffic through a multi-band from an access point (AP). The STA may include first to third STAs.

In step S3020, the STA decodes the first to third traffic. In this case, the first to third traffic is transmitted based on a result of carrier sensing for the multiple bands.

The multi band is aggregated with a first band and a second band. The first band includes a first primary channel and the second band includes a second primary channel.

If the multiple bands are combined into only two bands, the first band may be a 2.4 GHz or 5 GHz band, and the second band may be a 6 GHz band. If the third band is further combined with the third band, the first band may be a 2.4 GHz band, the second band may be a 5 GHz band, and the third band may be a 6 GHz band. However, the above-described configuration of the band is just one example, and the WLAN system may support various numbers of bands and channels.

The carrier sensing may be performed separately while simultaneously performing the first and second bands. In detail, the carrier sensing is performed based on a first backoff count (BC) value for the first band. The carrier sensing is performed based on a second BC value for the second band.

In addition, the carrier sensing may include physical carrier sensing and virtual carrier sensing. The physical carrier sensing may correspond to carrier sensing such as clear channel assessment (CCA), and the virtual carrier sensing may correspond to carrier sensing such as NAV (Network Allocation Vector) configuration. The physical carrier sensing and the virtual carrier sensing may be performed on the first and second primary channels.

In this case, the AP and the first STA support the multi-band.

When the first BC value becomes 0, the first traffic may be transmitted through the first band. When the second BC value becomes 0, the second traffic may be transmitted through the second band. That is, the AP may first transmit data (or traffic) to the STA through the band for the BC value which becomes 0. For example, if the first BC value becomes 0 first, the AP may perform carrier sensing for the second band even while transmitting the first traffic to the first STA. When the channel of the second band is idle, the second BC value is decreased, and when the second BC value is 0, the AP can transmit the second traffic to the first STA through the second band. have.

Carrier sensing for the first and second bands may correspond to carrier sensing for the first and second primary channels. Hereinafter, an embodiment in which the first traffic is transmitted based on carrier sensing in the first and second primary channels.

When it is determined that the first primary channel is idle, the first BC value may decrease. If it is determined that the second primary channel is idle, the second BC value may decrease. When the first and second BC values become zero, the first traffic may be transmitted through the first and second primary channels.

In addition, the AP may transmit traffic by performing carrier sensing to an STA that supports only a single band.

The AP may transmit the second traffic to a second STA based on a result of the carrier sensing. In addition, the AP may transmit the third traffic to a third STA based on a result of the carrier sensing.

When the first BC value becomes 0, the second traffic may be transmitted to the second STA through the first band. When the second BC value becomes 0, the third traffic may be transmitted to the third STA through the second band.

In this case, the second STA may support only the first band, and the third STA may support only the second band.

According to the embodiment described above, when the first BC value becomes 0, the AP may transmit the second traffic to the second STA through the first band. However, when performing the EDCA between the AP and the second STA, there may be a case where the second BC value becomes zero before the first BC value. Hereinafter, an EDCA method between the AP and the second STA will be described in consideration of the priority of the second traffic with other traffic.

If the second BC value becomes zero before the first BC value, if the second traffic has a higher priority than the third traffic, the first BC value is zero until the first BC value becomes zero. The 2 BC value can be reset. That is, the second traffic should be transmitted before the third traffic, but since the first BC value is not zero, the second traffic cannot be sent yet. In addition, the second traffic may not be transmitted to the second STA through the second band. Accordingly, the AP may randomly extract the second BC value again until the first BC value becomes zero.

When the second BC value becomes zero before the first BC value, if the second traffic has no priority with the third traffic, the third traffic may be transmitted before the second traffic. In other words, if there is no priority of traffic, it should be able to transmit any traffic first if it is ready to transmit regardless of traffic order. Accordingly, the AP may transmit the third traffic to the third STA before the second traffic. However, for fairness with terminals such as a second STA using only the first band, when the third traffic is sent, the first band and the second band are not aggregated even when the first band is idle. And transmits the third traffic using only the second band. Accordingly, the transmission opportunity of the STA using only the first band can be balanced with the transmission opportunity of the STA using the first and second bands at the same time.

The first to third traffic may be buffered for each access category (AC). The AC may include AC_VO (Voice), AC_VI (Video), AC_BE (Best Effort), and AC_BK (Background) as previously defined. For each AC the BC value can be set per band.

In addition, a new AC may be defined as follows by newly defining an EDCA Parameter Set element considering multi-band (or multi-link) operation. The first traffic may be buffered in AC for the multiple bands. The second traffic may be buffered in AC for the first band. The third traffic may be buffered in AC for the second band. The BC value for the AC for the multi-band can be set for each band. A first BC value may be set for AC for the first band. A second BC value may be set for the AC for the second band.

Hereinafter, a signaling scheme for multi-band aggregation will be described. In the present embodiment, it has been described as receiving configuration information for multiple bands, and signaling may be performed by using an FST configuration scheme.

The transmitter may transmit the multi-band setup request frame to the receiver. The transmitter may receive a multi-band setup response frame from the receiver.

The transmitter may transmit a multi-band Ack request frame to the receiver. The transmitter may receive a multi-band Ack response frame from the receiver.

The transmitter may include a first station management entity (SME), a first MAC layer management entity (MLME), and a second MLME. The receiver may include a second SME, a third MLME, and a fourth MLME.

The first MLME and the third MLME may be an entity supporting the first band, and the second MLME and the fourth MLME may be an entity supporting the second band.

The multi-band configuration request frame and the multi-band configuration response frame may be transmitted and received between the first MLME and the third MLME. The multi-band Ack request frame and the multi-band Ack response frame may be transmitted and received between the second MLME and the fourth MLME.

The first and second SMEs may generate primitives including multi-band parameters. The multiband parameter may include a channel number, an operating class, and a band identifier designated in the multiband. The primitive may be delivered to the first to fourth MLME.

When the multi-band method employs the FST setting method, the multi-band method includes four states, and includes rules on how to move from one state to the next state. The four states are Initial, Setup Completed, Transition Done, and Transition Confirmed.

In the Initial state, the transmitter and the receiver communicate in the old band / channel. At this time, when the FST setting request frame and the FST setting response frame are transmitted / received between the transmitter and the receiver, the apparatus moves to the Setup Complete state, and the transmitter and the receiver are ready to change the currently operating band / channel (s). do. FST sessions may be delivered in whole or in part to other bands / channels.

When the value of the LLT included in the FST setup request frame is 0, the LLT moves from the Setup Complete state to the Transition Done state, and enables the transmitter and the receiver to operate in different bands / channels.

Both the transmitter and receiver must successfully communicate on the new band / channel to reach the Transition Confirmed state. At this time, when the FST Ack request frame and the FST Ack response frame are transmitted / received between the transmitter and the receiver, the UE moves to the Transition Confirmed state, and the transmitter and the receiver form a complete connection in a new band / channel.

6. Device Configuration

FIG. 31 illustrates an apparatus for implementing the method as described above.

The wireless device 100 of FIG. 31 is a transmission device capable of implementing the above-described embodiment and may operate as an AP STA. The wireless device 150 of FIG. 31 is a reception device capable of implementing the above-described embodiment and may operate as a non-AP STA.

The transmitter 100 may include a processor 110, a memory 120, and a transceiver 130, and the receiver device 150 may include a processor 160, a memory 170, and a transceiver 180. can do. The transceivers 130 and 180 may transmit / receive radio signals and may be executed in a physical layer such as IEEE 802.11 / 3GPP. The processors 110 and 160 are executed at the physical layer and / or the MAC layer and are connected to the transceivers 130 and 180.

The processors 110 and 160 and / or the transceivers 130 and 180 may include an application-specific integrated circuit (ASIC), another chipset, a logic circuit, and / or a data processor. The memory 120, 170 may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium and / or other storage unit. When an embodiment is executed by software, the method described above can be executed as a module (eg, process, function) that performs the functions described above. The module may be stored in the memories 120 and 170 and may be executed by the processors 110 and 160. The memories 120 and 170 may be disposed inside or outside the processes 110 and 160, and may be connected to the processes 110 and 160 by well-known means.

The processors 110 and 160 may implement the functions, processes, and / or methods proposed herein. For example, the processors 110 and 160 may perform operations according to the above-described embodiment.

The operation of the processor 110 of the transmitting device is as follows. The processor 110 of the transmitting device generates first to third traffic and performs carrier sensing for multiple bands. In addition, the processor of the transmitter transmits traffic to the receiver through the multi-band based on the result of the carrier sensing.

The operation of the processor 160 of the receiving apparatus is as follows. The processor 160 of the receiving apparatus receives the first to third traffic transmitted based on the result of carrier sensing for multiple bands from the transmitting apparatus, and decodes the traffic.

32 illustrates a more detailed wireless device implementing an embodiment of the present invention. The present invention described above with respect to the transmitting apparatus or the receiving apparatus can be applied to this embodiment.

The wireless device includes a processor 610, a power management module 611, a battery 612, a display 613, a keypad 614, a subscriber identification module (SIM) card 615, a memory 620, a transceiver 630. ), One or more antennas 631, speakers 640, and microphones 641.

Processor 610 may be configured to implement the proposed functions, procedures, and / or methods described herein. Layers of the air interface protocol may be implemented in the processor 610. The processor 610 may include an application-specific integrated circuit (ASIC), another chipset, a logic circuit, and / or a data processing device. The processor may be an application processor (AP). The processor 610 may include at least one of a digital signal processor (DSP), a central processing unit (CPU), a graphics processing unit (GPU), and a modem (modulator and demodulator). Examples of processor 610 include SNAPDRAGONTM series processors manufactured by Qualcomm®, EXYNOSTM series processors manufactured by Samsung®, A Series processors manufactured by Apple®, HELIOTM series processors manufactured by MediaTek®, INTEL® It may be an ATOMTM series processor or a corresponding next generation processor manufactured by.

The power management module 611 manages power of the processor 610 and / or the transceiver 630. The battery 612 supplies power to the power management module 611. The display 613 outputs the result processed by the processor 610. Keypad 614 receives input to be used by processor 610. Keypad 614 may be displayed on display 613. SIM card 615 is an integrated circuit used to securely store an international mobile subscriber identity (IMSI) and its associated keys used to identify and authenticate subscribers in mobile phone devices such as mobile phones and computers. You can also store contact information on many SIM cards.

The memory 620 is operatively coupled with the processor 610 and stores various information for operating the processor 610. The memory 620 may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium, and / or other storage device. When an embodiment is implemented in software, the techniques described herein may be implemented as modules (eg, procedures, functions, etc.) that perform the functions described herein. The module may be stored in the memory 620 and executed by the processor 610. The memory 620 may be implemented inside the processor 610. Alternatively, the memory 620 may be implemented outside the processor 610 and communicatively connected to the processor 610 through various means known in the art.

The transceiver 630 is operatively coupled with the processor 610 and transmits and / or receives a radio signal. The transceiver 630 includes a transmitter and a receiver. The transceiver 630 may include a baseband circuit for processing radio frequency signals. The transceiver controls one or more antennas 631 to transmit and / or receive wireless signals.

The speaker 640 outputs a sound related result processed by the processor 610. The microphone 641 receives a sound related input to be used by the processor 610.

In the case of a transmitting apparatus, the processor 610 generates first to third traffic and performs carrier sensing for multiple bands. In addition, the processor of the transmitter transmits the traffic to the receiver through the multi-band based on the result of the carrier sensing.

In the case of a receiving apparatus, the processor 610 of the receiving apparatus receives the first to third traffic transmitted based on a result of carrier sensing for multiple bands from the transmitting apparatus, and decodes the traffic. .

The multi band is aggregated with a first band and a second band. The first band includes a first primary channel and the second band includes a second primary channel.

If the multiple bands are combined into only two bands, the first band may be a 2.4 GHz or 5 GHz band, and the second band may be a 6 GHz band. If the third band is further combined with the third band, the first band may be a 2.4 GHz band, the second band may be a 5 GHz band, and the third band may be a 6 GHz band. However, the above-described configuration of the band is just one example, and the WLAN system may support various numbers of bands and channels.

The carrier sensing may be performed separately while simultaneously performing the first and second bands. In detail, the carrier sensing is performed based on a first backoff count (BC) value for the first band. The carrier sensing is performed based on a second BC value for the second band.

In addition, the carrier sensing may include physical carrier sensing and virtual carrier sensing. The physical carrier sensing may correspond to carrier sensing such as clear channel assessment (CCA), and the virtual carrier sensing may correspond to carrier sensing such as NAV (Network Allocation Vector) configuration. The physical carrier sensing and the virtual carrier sensing may be performed on the first and second primary channels.

In this case, the AP and the first STA support the multi-band.

When the first BC value becomes 0, the first traffic may be transmitted through the first band. When the second BC value becomes 0, the second traffic may be transmitted through the second band. That is, the AP may first transmit data (or traffic) to the STA through the band for the BC value which becomes 0. For example, if the first BC value becomes 0 first, the AP may perform carrier sensing for the second band even while transmitting the first traffic to the first STA. When the channel of the second band is idle, the second BC value is decreased, and when the second BC value is 0, the AP can transmit the second traffic to the first STA through the second band. have.

Carrier sensing for the first and second bands may correspond to carrier sensing for the first and second primary channels. Hereinafter, an embodiment in which the first traffic is transmitted based on carrier sensing in the first and second primary channels.

When it is determined that the first primary channel is idle, the first BC value may decrease. If it is determined that the second primary channel is idle, the second BC value may decrease. When the first and second BC values become zero, the first traffic may be transmitted through the first and second primary channels.

In addition, the AP may transmit traffic by performing carrier sensing to an STA that supports only a single band.

The AP may transmit the second traffic to a second STA based on a result of the carrier sensing. In addition, the AP may transmit the third traffic to a third STA based on a result of the carrier sensing.

When the first BC value becomes 0, the second traffic may be transmitted to the second STA through the first band. When the second BC value becomes 0, the third traffic may be transmitted to the third STA through the second band.

In this case, the second STA may support only the first band, and the third STA may support only the second band.

According to the embodiment described above, when the first BC value becomes 0, the AP may transmit the second traffic to the second STA through the first band. However, when performing the EDCA between the AP and the second STA, there may be a case where the second BC value becomes zero before the first BC value. Hereinafter, an EDCA method between the AP and the second STA will be described in consideration of the priority of the second traffic with other traffic.

If the second BC value becomes zero before the first BC value, if the second traffic has a higher priority than the third traffic, the first BC value is zero until the first BC value becomes zero. The 2 BC value can be reset. That is, the second traffic should be transmitted before the third traffic, but since the first BC value is not zero, the second traffic cannot be sent yet. In addition, the second traffic may not be transmitted to the second STA through the second band. Accordingly, the AP may randomly extract the second BC value again until the first BC value becomes zero.

When the second BC value becomes zero before the first BC value, if the second traffic has no priority with the third traffic, the third traffic may be transmitted before the second traffic. In other words, if there is no priority of traffic, it should be able to transmit any traffic first if it is ready to transmit regardless of traffic order. Accordingly, the AP may transmit the third traffic to the third STA before the second traffic. However, for fairness with terminals such as a second STA using only the first band, when the third traffic is sent, the first band and the second band are not aggregated even when the first band is idle. And transmits the third traffic using only the second band. Accordingly, the transmission opportunity of the STA using only the first band can be balanced with the transmission opportunity of the STA using the first and second bands at the same time.

The first to third traffic may be buffered for each access category (AC). The AC may include AC_VO (Voice), AC_VI (Video), AC_BE (Best Effort), and AC_BK (Background) as previously defined. For each AC the BC value can be set per band.

In addition, a new AC may be defined as follows by newly defining an EDCA Parameter Set element considering multi-band (or multi-link) operation. The first traffic may be buffered in AC for the multiple bands. The second traffic may be buffered in AC for the first band. The third traffic may be buffered in AC for the second band. The BC value for the AC for the multi-band can be set for each band. A first BC value may be set for AC for the first band. A second BC value may be set for the AC for the second band.

Hereinafter, a signaling scheme for multi-band aggregation will be described. In the present embodiment, it has been described as receiving configuration information for multiple bands, and signaling may be performed by using an FST configuration scheme.

The transmitter may transmit the multi-band setup request frame to the receiver. The transmitter may receive a multi-band setup response frame from the receiver.

The transmitter may transmit a multi-band Ack request frame to the receiver. The transmitter may receive a multi-band Ack response frame from the receiver.

The transmitter may include a first station management entity (SME), a first MAC layer management entity (MLME), and a second MLME. The receiver may include a second SME, a third MLME, and a fourth MLME.

The first MLME and the third MLME may be an entity supporting the first band, and the second MLME and the fourth MLME may be an entity supporting the second band.

The multi-band configuration request frame and the multi-band configuration response frame may be transmitted and received between the first MLME and the third MLME. The multi-band Ack request frame and the multi-band Ack response frame may be transmitted and received between the second MLME and the fourth MLME.

The first and second SMEs may generate primitives including multi-band parameters. The multiband parameter may include a channel number, an operating class, and a band identifier designated in the multiband. The primitive may be delivered to the first to fourth MLME.

When the multi-band method employs the FST setting method, the multi-band method includes four states, and includes rules on how to move from one state to the next state. The four states are Initial, Setup Completed, Transition Done, and Transition Confirmed.

In the Initial state, the transmitter and the receiver communicate in the old band / channel. At this time, when the FST setting request frame and the FST setting response frame are transmitted / received between the transmitter and the receiver, the apparatus moves to the Setup Complete state, and the transmitter and the receiver are ready to change the currently operating band / channel (s). do. FST sessions may be delivered in whole or in part to other bands / channels.

When the value of the LLT included in the FST setup request frame is 0, the LLT moves from the Setup Complete state to the Transition Done state, and enables the transmitter and the receiver to operate in different bands / channels.

Both the transmitter and receiver must successfully communicate on the new band / channel to reach the Transition Confirmed state. At this time, when the FST Ack request frame and the FST Ack response frame are transmitted / received between the transmitter and the receiver, the UE moves to the Transition Confirmed state, and the transmitter and the receiver form a complete connection in a new band / channel.

Claims (17)

1. In a method for transmitting traffic in a WLAN system,

   Generating, by an access point, first to third traffic;

   Performing, by the AP, carrier sensing on multi-bands; And

   The AP transmitting the first traffic to the first STA through the multi-band based on a result of the carrier sensing;

   The multi-band is the first band and the second band is combined,

   The carrier sensing is performed based on a first backoff count (BC) value for the first band,

   The carrier sensing is performed based on a second BC value for the second band, and

   The AP and the first STA to support the multi-band

   Way.
2. The method of claim 1,

   When the first BC value becomes 0, the first traffic is transmitted through the first band,

   When the second BC value becomes zero, the second traffic is transmitted through the second band.

   Way.
3. The method of claim 2,

   The first band comprises a first primary channel,

   The second band includes a second primary channel,

   The carrier sensing includes physical carrier sensing and virtual carrier sensing,

   The physical carrier sensing and the virtual carrier sensing are performed for the first and second primary channels.

   Way.
4. The method of claim 2,

   If it is determined that the first primary channel is idle, the first BC value decreases,

   If it is determined that the second primary channel is idle, the second BC value decreases,

   When the first and second BC values become zero, the first traffic is transmitted through the first and second primary channels.

   Way.
5. The method of claim 1,

   Transmitting, by the AP, the second traffic to a second STA based on a result of the carrier sensing; And

   The AP further comprises the step of transmitting the third traffic to a third STA based on the result of the carrier sensing,

   When the first BC value becomes 0, the second traffic is transmitted to the second STA through the first band,

   When the second BC value becomes 0, the third traffic is transmitted to the third STA through the second band,

   The second STA supports only the first band,

   The third STA supports only the second band

   Way.
6. The method of claim 5,

   When the second BC value becomes zero before the first BC value,

   If the second traffic has a higher priority than the third traffic, the second BC value is reset until the first BC value becomes zero.

   Way.
7. The method of claim 5,

   When the second BC value becomes zero before the first BC value,

   If the second traffic has no priority with the third traffic, the third traffic is transmitted before the second traffic.

   Way.
8. The method of claim 1,

   The first to third traffic is buffered for each access category (AC), or

   The first traffic is buffered in AC for the multi-band,

   The second traffic is buffered in AC for the first band,

   The third traffic is buffered in AC for the second band.

   Way.
9. In an access point (AP) for transmitting traffic in a WLAN system, the AP,

   Memory;

   Transceiver; And

   A processor operatively coupled with the memory and the transceiver, the processor comprising:

   Generate first to third traffic;

   Perform carrier sensing on multi-bands; And

   The first traffic is transmitted to the first STA through the multi-band based on the carrier sensing result.

   The multi-band is the first band and the second band is combined,

   The carrier sensing is performed based on a first backoff count (BC) value for the first band,

   The carrier sensing is performed based on a second BC value for the second band, and

   The AP and the first STA to support the multi-band

   Wireless device.
10. The method of claim 9,

    When the first BC value becomes 0, the first traffic is transmitted through the first band,

    When the second BC value becomes zero, the second traffic is transmitted through the second band.

    Wireless device.
11. The method of claim 10,

    The first band comprises a first primary channel,

    The second band includes a second primary channel,

    The carrier sensing includes physical carrier sensing and virtual carrier sensing,

    The physical carrier sensing and the virtual carrier sensing are performed for the first and second primary channels.

    Wireless device.
12. The method of claim 10,

    If it is determined that the first primary channel is idle, the first BC value decreases,

    If it is determined that the second primary channel is idle, the second BC value decreases,

    When the first and second BC values become zero, the first traffic is transmitted through the first and second primary channels.

    Wireless device.
13. The method of claim 9,

    The processor sends the second traffic to a second STA based on a result of the carrier sensing; And

    The processor may transmit the third traffic to a third STA based on a result of the carrier sensing.

    When the first BC value becomes 0, the second traffic is transmitted to the second STA through the first band,

    When the second BC value becomes 0, the third traffic is transmitted to the third STA through the second band,

    The second STA supports only the first band,

    The third STA supports only the second band

    Wireless device.
14. The method of claim 13,

    When the second BC value becomes zero before the first BC value,

    If the second traffic has a higher priority than the third traffic, the second BC value is reset until the first BC value becomes zero.

    Wireless device.
15. The method of claim 13,

    When the second BC value becomes zero before the first BC value,

    If the second traffic has no priority with the third traffic, the third traffic is transmitted before the second traffic.

    Wireless device.
16. The method of claim 9,

    The first to third traffic is buffered for each access category (AC), or

    The first traffic is buffered in AC for the multi-band,

    The second traffic is buffered in AC for the first band,

    The third traffic is buffered in AC for the second band.

    Wireless device.
17. In the method for receiving traffic in a WLAN system,

    Receiving, by a station (STA), first through third traffic over a multi-band from an access point (AP); And

    Decoding, by the STA, the first to third traffic;

    The first to third traffic is transmitted based on the results of carrier sensing for the multi-band,

    The multi-band is the first band and the second band is combined,

    The carrier sensing is performed based on a first backoff count (BC) value for the first band,

    The carrier sensing is performed based on a second BC value for the second band, and

    The AP and the first STA to support the multi-band

    Way.

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