WO2018038354A1 - 무선랜 시스템에서 프레임을 송신하는 방법 및 이를 이용한 무선단말 - Google Patents
무선랜 시스템에서 프레임을 송신하는 방법 및 이를 이용한 무선단말 Download PDFInfo
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Definitions
- the present disclosure relates to wireless communication, and more particularly, to a method for transmitting a frame in a WLAN system and a wireless terminal using the same.
- next-generation WLANs 1) enhancements to the Institute of Electronics and Electronics Engineers (IEEE) 802.11 physical physical access (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.
- IEEE Institute of Electronics and Electronics Engineers
- PHY physical physical access
- MAC medium access control
- next-generation WLAN The environment mainly considered in the next-generation WLAN is a dense environment having many access points (APs) and a station (STA), and improvements in spectral efficiency and area throughput are discussed in such a dense environment.
- 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.
- scenarios such as a wireless office, a smarthome, a stadium, and a hotspot are of interest in the next generation WLAN.
- a discussion of performance improvement of a WLAN system in an environment in which APs and STAs are concentrated is in progress.
- An object of the present specification is to provide a method for transmitting a frame in a WLAN system having an improved performance and a wireless terminal using the same.
- the present specification relates to a method for transmitting a frame in a WLAN system.
- a time parameter indicating a time used for transmission of a wireless terminal is compared with a preset allowable time and an AP (access) is accessed through an EDCA. point), adding a first request time for transmission of the first frame to a time parameter, receiving a trigger frame from the AP for multi-user uplink (MU UL) transmission, and Performing data processing for the second frame transmitted in response to the trigger frame, wherein the second request time for transmission of the second frame does not add up to a time parameter.
- MU UL multi-user uplink
- a method for transmitting a frame in a WLAN system having improved performance and a wireless terminal using the same are provided.
- FIG. 1 is a conceptual diagram illustrating a structure of a WLAN system.
- FIG. 2 is a diagram illustrating an example of a PPDU used in the IEEE standard.
- FIG. 3 is a diagram illustrating an example of a HE PPDU.
- 4 is a diagram illustrating an arrangement of resource units used on a 20 MHz band.
- 5 is a diagram illustrating an arrangement of resource units used on a 40 MHz band.
- 6 is a diagram illustrating an arrangement of resource units used on an 80 MHz band.
- FIG. 7 is a diagram illustrating another example of the HE-PPDU.
- FIG. 8 is a block diagram illustrating an example of HE-SIG-B.
- FIG. 9 shows an example of a trigger frame.
- FIG 11 shows an example of subfields included in individual user information fields.
- FIG. 12 is a diagram illustrating a conceptual diagram of an STA inside an EDCA procedure in a WLAN system according to the present embodiment.
- FIG. 13 is a conceptual diagram illustrating a backoff procedure according to an EDCA procedure of the present embodiment.
- FIG. 14 is a view illustrating a backoff period and a frame transmission procedure in a wireless LAN system of the present specification.
- 15 is a diagram illustrating a method for transmitting a frame in a WLAN system performed by a wireless terminal according to an embodiment of the present invention.
- 16 is a flowchart illustrating a method of transmitting a frame in a WLAN system performed by a wireless terminal according to an embodiment of the present invention.
- 17 is a block diagram illustrating a wireless terminal to which the present embodiment can be applied.
- FIG. 1 is a conceptual diagram illustrating a structure of a WLAN system.
- FIG. 1A shows the structure of an infrastructure network of the Institute of Electrical and Electronic Engineers (IEEE) 802.11.
- IEEE Institute of Electrical and Electronic Engineers
- the WLAN system 10 of FIG. 1A may include at least one basic service set (hereinafter, referred to as 'BSS', 100, 105).
- the BSS is a set of access points (APs) and stations (STAs) that can successfully synchronize and communicate with each other, and is not a concept indicating a specific area.
- APs access points
- STAs stations
- the first BSS 100 may include a first AP 110 and one first STA 100-1 coupled with the first AP 110.
- the second BSS 105 may include a second AP 130 and one or more STAs 105-1 and 105-2 coupled with the second AP 130.
- the infrastructure BSS may include at least one STA, AP (110, 130) providing a distribution service (Distribution Service) and a distribution system (DS, 120) connecting a plurality of APs. have.
- the distributed system 110 may connect the plurality of BSSs 100 and 105 to implement an extended service set 140 which is an extended service set.
- the ESS 140 may be used as a term indicating one network to which at least one AP 110 or 130 is connected through the distributed system 120.
- At least one AP included in one ESS 140 may have the same service set identification (hereinafter, referred to as SSID).
- the portal 150 may serve as a bridge for connecting the WLAN network (IEEE 802.11) with another network (for example, 802.X).
- a network between APs 110 and 130 and a network between APs 110 and 130 and STAs 100-1, 105-1, and 105-2 may be implemented. Can be.
- FIG. 1B is a conceptual diagram illustrating an independent BSS.
- the WLAN system 15 of FIG. 1B performs communication by setting a network between STAs without the APs 110 and 130, unlike FIG. 1A. It may be possible to.
- a network that performs communication by establishing a network even between STAs without the APs 110 and 130 is defined as an ad-hoc network or an independent basic service set (BSS).
- BSS basic service set
- the IBSS 15 is a BSS operating in an ad-hoc mode. Since IBSS does not contain an AP, there is no centralized management entity. Thus, in the IBSS 15, the STAs 150-1, 150-2, 150-3, 155-4, and 155-5 are managed in a distributed manner.
- All STAs 150-1, 150-2, 150-3, 155-4, and 155-5 of the IBSS may be mobile STAs, and access to a distributed system is not allowed. All STAs of the IBSS form a self-contained network.
- the STA referred to herein includes a medium access control (MAC) conforming to the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard and a physical layer interface to a wireless medium.
- MAC medium access control
- IEEE Institute of Electrical and Electronics Engineers 802.11
- any functional medium it can broadly be used to mean both an AP and a non-AP Non-AP Station (STA).
- the STA referred to herein includes a mobile terminal, a wireless device, a wireless transmit / receive unit (WTRU), a user equipment (UE), and a mobile station (MS). It may also be called various names such as a mobile subscriber unit or simply a user.
- WTRU wireless transmit / receive unit
- UE user equipment
- MS mobile station
- FIG. 2 is a diagram illustrating an example of a PPDU used in the IEEE standard.
- PPDUs PHY protocol data units
- LTF and STF fields included training signals
- SIG-A and SIG-B included control information for the receiving station
- 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 or SIG-B.
- 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.
- FIG. 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 may be included only for the multi-user, and the HE-SIG-B may be omitted in the PPDU for the single user.
- a HE-PPDU for a multiple user 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)
- L-STF legacy-short training field
- L-SIG-A High efficiency-signal A
- HE-SIG-B high efficiency-signal-B
- HE-STF high efficiency-long training field
- HE-LTF High efficiency-long training field
- 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.
- resource units (RUs) used on a 20 MHz band.
- resource units (RUs) corresponding to different numbers of tones may be used to configure some fields of the HE-PPDU.
- resources may be allocated in units of RUs shown for HE-STF, HE-LTF, and data fields.
- 26-units ie, units corresponding to 26 tones
- 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.
- seven DC tones are inserted into the center band, that is, the DC band, and 26-units corresponding to each of the 13 tones may exist to the left and right of the DC band.
- other bands may be allocated 26-unit, 52-unit, 106-unit. Each unit can be assigned for a receiving station, i. E. A user.
- 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.
- FIG. 5 is a diagram illustrating an arrangement of resource units (RUs) used on a 40 MHz band.
- the example of FIG. 5 may also use 26-RU, 52-RU, 106-RU, 242-RU, 484-RU, and the like.
- 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.
- 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.
- FIG. 6 is a diagram illustrating an arrangement of resource units (RUs) used on an 80 MHz band.
- the example of FIG. 6 may also use 26-RU, 52-RU, 106-RU, 242-RU, 484-RU, 996-RU, and the like. have.
- seven or five DC tones can be inserted at the center frequency, and 12 tones are used as the guard band in the leftmost band of the 80 MHz band, and in the rightmost band of the 80 MHz band. Eleven tones can be used as guard bands.
- 996-RU may be used when used for a single user. Meanwhile, the specific number of RUs may be changed as in the example of FIGS. 4 and 5.
- FIG. 7 is a diagram illustrating another example of the HE-PPDU.
- FIG. 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.
- AGC automatic gain control
- 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.
- the L-SIG 720 may be repeatedly transmitted. That is, the L-SIG 720 may be configured in a repeating 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.
- 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 40, 80, 160, 80 + 80 Mhz, 5) Field indicating MCS scheme applied to HE-SIG-B, 6) HE-SIB-B is dual subcarrier modulation for MCS ( field indicating whether it is modulated by dual subcarrier modulation), 7) field indicating the number of symbols used for HE-SIG-B, and 8) indicating whether HE-SIG-B is generated over the entire band.
- PE Packet Extension
- CRC field of the HE-SIG-A and the like.
- 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.
- MU multi-user
- 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 730 or the HE-SIG-B 740 may include resource allocation information (or virtual resource allocation information) for at least one receiving STA.
- the HE-SIG-B 740 is described in more detail with reference to FIG. 8 described below.
- the previous field of the HE-SIG-B 740 on the MU PPDU may be transmitted in duplicated form.
- the HE-SIG-B 740 transmitted in a part of the frequency band (for example, the fourth frequency band) is the frequency band (that is, 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 be included.
- 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.
- the HE-SIG-B 740 may be transmitted in an 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 orthogonal frequency-division multiple access (OFDMA) environment.
- MIMO multiple input multiple output
- OFDMA orthogonal frequency-division multiple access
- 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.
- 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.
- 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
- the second field may include a field related to a HE system.
- 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
- 2048 FFT for a bandwidth of 160 MHz continuous or discontinuous 160 MHz.
- / IFFT can be applied.
- spacing may be applied to a subcarrier having a size of 312.5 kHz, which is a conventional subcarrier spacing, and space may be applied to a subcarrier having a size of 78.125 kHz, as a second field of the HE PPDU.
- 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 ⁇ s, 0.8 ⁇ s, 1.6 ⁇ s, 2.4 ⁇ s, 3.2 ⁇ s.
- 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.
- the main band of the first field L-STF, L-LTF, L-SIG, HE-SIG-A, HE-SIG-B
- HE-STF the main band of the first field
- HE-LTF, Data the second field
- 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 may receive the HE-SIG-A 730 and may be instructed to receive the downlink PPDU based on the HE-SIG-A 730.
- the STA may perform decoding based on the changed FFT size from the field after the HE-STF 750 and the HE-STF 750.
- the STA may stop decoding and configure a network allocation vector (NAV).
- NAV network allocation vector
- 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.
- data (or frame) transmitted from the AP to the STA is downlink data (or downlink frame), and data (or frame) transmitted from the STA to the AP is called uplink data (or uplink frame).
- downlink data or downlink frame
- uplink data or uplink frame
- the transmission from the AP to the STA may be expressed in terms of downlink transmission
- the transmission from the STA to the AP may be expressed in terms of uplink transmission.
- 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)).
- PSDU physical layer service data unit
- MPDU MAC protocol data unit
- the PPDU header may include a PHY header and a PHY preamble
- 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
- the PHY preamble may be expressed as a PLCP preamble in another term.
- each of the PPDUs, frames, and data transmitted through uplink transmission may be represented by the term uplink PPDU, uplink frame, and uplink data.
- the entire bandwidth may be used for downlink transmission to one STA and uplink transmission to one STA based on single (or single) -orthogonal frequency division multiplexing (SUDM) transmission.
- 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.
- orthogonal frequency division multiple access (OFDMA) based transmission method is preferably supported for uplink transmission and downlink transmission. That is, uplink / downlink communication may be performed by allocating data units (eg, RUs) corresponding to different frequency resources to the user.
- the AP performs OFDMA.
- DL MU transmission may be performed based on the above, and such transmission may be expressed in terms of DL MU OFDMA transmission.
- the AP may transmit downlink data (or downlink frame, downlink PPDU) to each of the plurality of STAs through 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) is performed on a specific subband (or subchannel) allocated for DL MU OFDMA transmission. Can be.
- UL MU transmission uplink multi-user transmission
- a plurality of STAs transmit data to an AP on the same time resource.
- Uplink transmission on the overlapped time resource by each of the plurality of STAs may be performed in the frequency domain or the spatial domain.
- different frequency resources may be allocated as uplink transmission resources for each of the plurality of STAs based on OFDMA.
- the 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 allocated frequency resources.
- the transmission method through these different frequency resources may be represented by the term UL MU OFDMA transmission method.
- each of the plurality of STAs When uplink transmission by each of the plurality of STAs is performed in 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.
- 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.
- 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.
- 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.
- 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.
- OBSS overlapped BSS
- the STA can transmit the frame only through the primary channel, thereby being limited 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.
- a WLAN system supporting the OFDMA technology supporting the OFDMA technology. That is, the above-described OFDMA technique is applicable to at least one of downlink and uplink.
- the above-described MU-MIMO technique may be additionally applied to at least one of downlink and uplink.
- 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 the operation of radio resources can be improved.
- the AP 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 may 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).
- OFDMA orthogonal frequency division multiple access
- Different frequency resources for each of the plurality of STAs may be indicated through a trigger frame.
- FIG. 8 is a block diagram illustrating an example of HE-SIG-B.
- 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.
- 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-specific field" for two users (2 users), a CRC field corresponding thereto, and the like, as shown.
- the trigger frame of FIG. 9 allocates resources for uplink multiple-user transmission and can 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 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 includes time information for setting the NAV described below.
- Information about an identifier (eg, association identifier, hereinafter 'AID') of the terminal may be included.
- 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 a corresponding trigger frame, and the common information field 950 is common to be applied to a receiving STA that receives the corresponding trigger frame. Contains control information.
- 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 referred to as a "RU assignment field.”
- 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.
- FIG. 10 shows an example of 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 illustrated length field 1010 has the same value as the length field of the L-SIG field of the uplink PPDU transmitted corresponding to the trigger frame, and the length field of the L-SIG field of the uplink PPDU indicates the length of the uplink PPDU.
- the length field 1010 of the trigger frame may be used to indicate the length of the corresponding uplink PPDU.
- the cascade indicator field 1020 indicates whether a cascade operation is performed.
- the cascade operation means that downlink MU transmission and uplink MU transmission are performed together in the same TXOP. That is, after downlink MU transmission is performed, it means that uplink MU transmission is performed after a predetermined time (eg, SIFS).
- a predetermined time eg, SIFS.
- only one transmitting device (eg, AP) for downlink communication may exist, and a plurality of transmitting devices (eg, non-AP) for uplink communication may exist.
- the CS request field 1030 indicates whether the state of the radio medium, the NAV, or the like should be considered in a situation in which the receiving apparatus receiving the trigger frame transmits the corresponding uplink PPDU.
- the HE-SIG-A information field 1040 may include information for controlling the content of the SIG-A field (ie, the HE-SIG-A field) of the uplink PPDU transmitted in response to the corresponding trigger frame.
- the CP and LTF type field 1050 may include information about the length of the LTF and the CP length of the uplink PPDU transmitted in response to the corresponding trigger frame.
- the trigger type field 1060 may indicate the purpose for which the corresponding trigger frame is used, for example, normal triggering, triggering for beamforming, a request for Block ACK / NACK, and the like.
- FIG. 11 illustrates an example of subfields included in an individual 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 1110 of FIG. 11 indicates an identifier of an STA (ie, a receiving STA) to which per user information corresponds.
- An example of the identifier may be all or part of an AID. have.
- 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.
- the RU indicated by the RU Allocation field 1120 preferably indicates the RUs shown in FIGS. 4, 5, and 6.
- the subfield of FIG. 11 may include a 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 an 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. 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.
- FIG. 12 is a diagram illustrating a conceptual diagram of an STA inside an EDCA procedure in a WLAN system according to the present embodiment.
- an STA may perform an enhanced distributed channel access (EDCA) procedure based on a plurality of predefined user priorities for buffered traffic data.
- the buffered traffic data may be a Quality of Service (QoS) frame based on a plurality of user priorities.
- QoS Quality of Service
- EDs access categories for the EDCA procedure may be defined as AC_BK (background), AC_BE (best effort), AC_VI (video), and AC_VO (voice).
- AC_BK background
- AC_BE best effort
- AC_VI video
- AC_VO voice
- the STA performing the EDCA procedure arrives from the logical link control (LLC) layer to the medium access control (MAC) layer, that is, maps traffic data such as a MAC service data unit (MSDU) to a specific AC as shown in Table 1 below. can do.
- LLC logical link control
- MAC medium access control
- Table 1 is an exemplary table showing the mapping between user priority and AC.
- a transmission queue and a channel access parameter set may be defined for each AC.
- a plurality of user priorities may be implemented based on a channel access parameter set differently set for each AC.
- the STA may replace the conventional parameter set (eg, DCF interframe space (DIFS), CWmin and CWmax) according to a conventional distributed coordination function (DCF).
- DIFS DCF interframe space
- CWmin and CWmax DCF interframe space
- DCF distributed coordination function
- a channel access parameter set eg, arbitration interframe space (AIFS) [AC], CWmin [AC], and CWmax [AC]
- AIFS arbitration interframe space
- the EDCA parameter set element can be an important means used to differentiate channel access of STAs transmitting QoS traffic with differential user priorities. For example, as the values of AIFS [AC] and CWmin [AC] corresponding to each AC are smaller, the delay time for channel access is shorter, and thus differential user priority may be implemented.
- the EDCA parameter set element included in the beacon frame may include a channel access parameter set (ie, AIFS [AC], CWmin [AC], CWmax [AC]) for each AC.
- the channel access parameter set used for each AC may be set to a default value in the STA.
- the differential backoff procedure may be performed separately for each AC. Properly setting the set of channel access parameters for each AC can optimize network performance while increasing transmission performance based on traffic priority.
- a user priority predefined for traffic data may be referred to as a traffic identifier (hereinafter, 'TID'). Transmission priority of traffic data may be determined based on user priority.
- the traffic identifier (TID) of the traffic data having the highest user priority may be set to '7'. That is, traffic data in which the traffic identifier (TID) is set to '7' may be understood as traffic having the highest transmission priority.
- one STA (or AP) 1200 may include a virtual mapper 1210, a plurality of transmission queues 1220-1250, and a virtual collision processor 1260.
- the virtual mapper 1210 of FIG. 12 may map an MSDU received from a logical link control (LLC) layer to a transmission queue corresponding to each AC according to Table 1 above.
- LLC logical link control
- the transmission queue 1220 of the AC VO type of FIG. 12 may include one frame 1221 for a second STA (not shown).
- the transmission queue 1230 of the AC VI type has three frames 1231 to 1233 for the first STA (not shown) and one frame 1234 for the third STA (not shown) according to the order to be transmitted to the physical layer. ) May be included.
- the transmission queue 1240 of the AC BE type of FIG. 12 includes one frame 1241 for the second STA (not shown) and one frame for the third STA (not shown) according to the order to be transmitted to the physical layer. 1242 and one frame 1243 for a second STA (not shown).
- the AC BE type transmission queue 1250 may not include a frame to be transmitted to the physical layer.
- the plurality of transmission queues 1220-1250 of FIG. 12 may operate as individual competition entities in the EDCA procedure within the STA to determine traffic to be transmitted over the wireless medium in one STA (or AP).
- the transmission queue 1220 of the AC VO type, the transmission queue 1230 of the AC VI type, and the transmission queue 1240 of the AC BE type having the buffered traffic in the transmission queue of FIG. Can be understood as an entity.
- the transmission queue 1220 of the AC VO type, the transmission queue 1230 of the AC VI type, and the transmission queue 1240 of the AC BE type include a channel access parameter set for each AC (i.e., AIFS [AC], CWmin [ AC], CWmax [AC]) can be used to perform the EDCA procedure.
- AIFS [AC], CWmin [ AC], CWmax [AC] can be used to perform the EDCA procedure.
- the specific transmission queue that obtained the channel access through the EDCA procedure inside the STA may be referred to as primary AC.
- Traffic included in the primary AC may be transmitted to another entity (eg, another STA or AP) during a transmission opportunity (TXOP).
- another entity eg, another STA or AP
- the collision between the ACs may be adjusted through a virtual collision handler 1260 in the STA.
- a frame buffered in an AC with a higher priority may be transmitted first.
- Other ACs may also increase the contention window value and update the value set in the backoff count.
- TXOP may be initiated when the STA accesses the wireless medium based on the rules of the EDCA procedure. If two or more frames are included in one AC, if a TXOP is obtained by the STA, the STA may attempt to transmit a plurality of frames through the MAC layer.
- the STA may attempt to transmit the next frame after an SIFS time interval. do.
- the TXOP limit value may be set as a default value for the AP and the STA, or a frame associated with the TXOP limit value may be transferred from the AP to the STA. If the size of the data frame to be transmitted exceeds the TXOP limit value, the STA may split the frame into several smaller frames. The divided frame may be transmitted within a range not exceeding the TXOP limit value.
- the backoff procedure for generating a new backoff count of the STA is understood based on the existing backoff procedure of the DCF. Can be.
- each STA may individually determine a frame to be transmitted in each STA through an internal backoff procedure associated with a plurality of internal transmission queues.
- Each STA may set a backoff time in a backoff counter for each STA based on an individually determined frame.
- Each STA may perform a contention-based back-off procedure with another STA based on the backoff counter. In this case, the STA whose first backoff time is '0' may acquire a transmission opportunity (TXOP).
- TXOP transmission opportunity
- traffic data (or traffic) to be transmitted in an STA may be transmitted according to a contention-based EDCA procedure according to user priority.
- the priority given to each traffic data may be set to any one of the eight user priorities of Table 1 above.
- one STA may include four output queues (ie, transmission queues). Each output queue can individually perform channel access operations according to the rules of the EDCA procedure. Each output queue may transmit traffic data based on an Arbitration Interframe Space (AIFS) value that is differentiated according to user priority instead of a previously used DCF Interframe Space (DIFS).
- AIFS Arbitration Interframe Space
- DIFS DCF Interframe Space
- the WLAN system may minimize the occurrence of collision between STAs by adjusting the transmission of the traffic having high user priority.
- each STA may set a backoff time (Tb [i]) to the backoff timer.
- the backoff time Tb [i] may be calculated using the following Equation 1 as a pseudo-random integer value.
- Random (i) is a function that generates a random integer between 0 and CW [i] using a uniform distribution.
- CW [i] is the contention window between the minimum contention window CWmin [i] and the maximum contention window CWmax [i], and i may indicate user priority.
- Equation 2 When the STA performing the EDCA procedure transmits a frame, when a collision occurs in a relationship with another STA and retransmission is required, Equation 2 below may be used. That is, each time a collision occurs, a new contention window CW new [i] may be calculated using the previous window CW old [i].
- the PF value may be calculated according to the procedure defined in the IEEE 802.11e standard.
- the CWmin [i], CWmax [i], AIFS [i] and PF values included in the channel access parameter set may be set as default values for each STA (or AP).
- the channel access parameter set may be received from the AP through a QoS parameter set element included in a management frame or a beacon frame.
- the terminal may be a device capable of supporting both the WLAN system and the cellular system. That is, the terminal may be interpreted as a UE supporting the cellular system or an STA supporting the WLAN system.
- the backoff procedure of the EDCA procedure may be performed based on Equations 1 and 2 above.
- the AC VI type transmission queue 1230 of FIG. 12 is a transmission opportunity for accessing a wireless medium.
- 'TXOP' can be obtained.
- the AP 1200 of FIG. 12 may determine the transmission queue 1230 of the AC VI type as the primary AC, and the remaining transmission queues 1220, 1240, and 1250 may be determined as the secondary AC.
- a process of determining the transmission queue in which the backoff procedure is completed first as the primary AC by performing the backoff procedure on the plurality of transmission queues 1220 to 1250 is referred to herein as a primary AC rule. May be referred to.
- a transmission opportunity period for a transmission opportunity may be determined based on the primary AC determined by the primary AC rule.
- frames included in the secondary AC may be transmitted together in a transmission opportunity period determined based on the primary AC.
- the EDCA procedure of the user STA may be activated or deactivated in the WLAN system according to the present embodiment. For example, whether to activate the EDCA procedure may be determined in the association phase or negotiation phase of the STA and the AP. Alternatively, whether to activate the EDCA procedure may be signaled to the AP through a separate frame (eg, an OMI frame) after being determined by the STA.
- a separate frame eg, an OMI frame
- the horizontal axes t1 to t5 for the first to fifth STAs 1410 to 1450 may represent time axes.
- the vertical axis for the first to fifth STAs 1410 to 1450 may indicate a backoff time transmitted.
- a plurality of STAs may attempt data (or frame) transmission.
- each STA selects the backoff time (Tb [i]) of Equation 1 and waits for the corresponding slot time (slot time) before transmitting. You can try
- each STA may count down the selected backoff count time in slot time units. Each STA may continue to monitor the medium while counting down. If the medium is monitored as occupied, the STA may stop counting down and wait. If the medium is monitored in an idle state, the STA can resume counting down.
- the third STA 1430 may check whether the medium is idle during DIFS. Subsequently, when the medium is determined to be idle during DIFS, the third STA 1430 may transmit a frame to an AP (not shown).
- IFS inter frame space
- a frame may reach the MAC layer of each of the first STA 1410, the second STA 1420, and the fifth STA 1450. If the medium is identified as idle, each STA may wait for DIFS and then count down the individual backoff time selected by each STA.
- the second STA 1420 selects the smallest backoff time and the first STA 1410 selects the largest backoff count value.
- the remaining backoff time of the fifth STA 1450 is the remaining back of the first STA 1410 at the time T1 after completing the backoff procedure for the backoff time selected by the second STA 1420 and starting the frame transmission. A case shorter than the off time is shown.
- the first STA 1410 and the fifth STA 1450 may suspend and wait for the backoff procedure. Subsequently, when the media occupation of the second STA 1420 ends (that is, the medium is idle again), the first STA 1410 and the fifth STA 1450 may wait as long as DIFS.
- the first STA 1410 and the fifth STA 1450 may resume the backoff procedure based on the remaining remaining backoff time.
- the fifth STA 1450 may complete the backoff procedure before the first STA 1410. Can be.
- a frame for the fourth STA 1440 may reach the MAC layer of the fourth STA 1440.
- the fourth STA 1440 may wait as much as DIFS. Subsequently, the fourth STA 1440 may count down the backoff time selected by the fourth STA 1440.
- the remaining backoff time of the fifth STA 1450 may coincide with the backoff time of the fourth STA 1440. In this case, a collision may occur between the fourth STA 1440 and the fifth STA 1450. When a collision occurs between STAs, neither the fourth STA 1440 nor the fifth STA 1450 may receive an ACK, and may fail to transmit data.
- the fourth STA 1440 and the fifth STA 1450 may separately calculate a new contention window CW new [i] according to Equation 2 above. Subsequently, the fourth STA 1440 and the fifth STA 1450 may separately perform countdowns for the newly calculated backoff time according to Equation 2 above.
- the first STA 1410 may wait. Subsequently, when the medium is idle, the first STA 1410 may resume backoff counting after waiting for DIFS. When the remaining backoff time of the first STA 1410 elapses, the first STA 1410 may transmit a frame.
- the CSMA / CA mechanism may include virtual carrier sensing in addition to physical carrier sensing in which the AP and / or STA directly sense the medium.
- Virtual carrier sensing is intended to compensate for problems that may occur in media access, such as a hidden node problem.
- the MAC of the WLAN system uses a Network Allocation Vector (NAV).
- NAV Network Allocation Vector
- the NAV is a value that indicates to the other AP and / or STA how long the AP and / or STA currently using or authorized to use the medium remain until the medium becomes available.
- the value set to NAV corresponds to a period in which the medium is scheduled to be used by the AP and / or STA transmitting the frame, and the STA receiving the NAV value is prohibited from accessing the medium during the period.
- the NAV may be set according to a value of a duration field of the MAC header of the frame.
- 15 is a diagram illustrating a method for transmitting a frame in a WLAN system performed by a wireless terminal according to an embodiment of the present invention.
- the horizontal axis of the AP 1510 of FIG. 15 may represent a time t1 and the vertical axis may be associated with the existence of a frame transmitted by the AP 1510.
- the horizontal axis of the STA 1520 of FIG. 15 may represent time t2, and the vertical axis may be associated with the presence of a frame transmitted by the STA 1520.
- the STA 1520 may be understood as a reception terminal of a trigger frame in which a plurality of resource units for uplink transmission of a plurality of user STAs are individually allocated.
- the STA 1520 may maintain two parameters (used_time and admitted_time) for each of the ACs AC_VO, AC_VI, AC_BE, and AC_BK illustrated in FIG. 12.
- the STA 1520 may include a plurality of first time parameters corresponding to an admitted_time for each AC (AC VO, AC VI, AC BE, AC BK), and a plurality of first time parameters corresponding to the used time (used_time).
- the second time parameter of may be maintained.
- the plurality of first time parameters may include a first time parameter for an allowed time of AC VO, a first time parameter for an allowed time of AC VI, a first time parameter for an allowed time of AC BE, and It can be understood as a concept including a first time parameter for the allowable time of AC BK.
- the plurality of second time parameters include a second time parameter for the usage time of the AC VO, a second time parameter for the usage time of the AC VI, a second time parameter for the usage time of the AC BE, and AC BK. It can be understood as a concept including a second time parameter for the use time of.
- the STA 1520 of FIG. 15 transmits traffic data included in a specific AC of four ACs in order to transmit a frame through the contention-based EDCA referred to in FIGS. 12 to 14. If desired), a first time parameter and a second time parameter corresponding to an AC including the corresponding frame may be compared.
- the plurality of first time parameters corresponding to the allowed time (admitted_time) and the plurality of second time parameters corresponding to the used time (used_time) may be set to initial values (i.e., in the association (or recombination) step between the user STA and the AP. For example, it may be set to '0'.
- the plurality of first time parameters corresponding to the allowed time may be understood as values preset by the AP.
- the plurality of first time parameters corresponding to the allowed time may be calculated based on Equation 3 below.
- the value set in the admitted_time ' may indicate the time allowed from the AP for the user STA before each AC.
- the value corresponding to 11EDCAAveragingPeriod and the value corresponding to the medium time of TSPEC are based on an add traffic stream (ADDTS) response frame received from the AP in the session establishment step. It may be set to.
- ADDTS add traffic stream
- the add traffic stream (ADDTS) response frame may be a frame received in response to an ADDTS request frame transmitted by the user STA to form a session of the user STA.
- a TSPEC element (traffic specification) may be included in an add traffic stream (ADDTS) response frame.
- a value corresponding to the medium time of the TSPEC may be set for each AC based on a TSPEC element (traffic specification).
- the plurality of second time parameters corresponding to the usage time used_time may indicate a time used for transmission of the user STA.
- a plurality of second time parameters corresponding to the usage time used_time may be calculated based on Equation 4 below.
- a value set in used_time ' may indicate a time used by the user STA before each AC.
- the value set in MPDUExchangeTime is a first processing time required for transmission of a frame of a specific AC to be transmitted currently, and a first processing time required for reception of an acknowledgment frame for a frame of a specific AC to be currently transmitted. 2 can be understood as the sum of the processing time and the time corresponding to SIFS.
- the user STA sets a value set in MPDUExchangeTime for the specific AC at a time (used_time ') used by the user STA before the specific AC according to equation (4). By summing, it is possible to update the second time parameter corresponding to the usage time (used_time) of the specific AC.
- the STA 1520 may use a first time parameter corresponding to an admitted_time of a specific AC and a use time of a specific AC to transmit a frame corresponding to a specific AC through an EDCA. Compare a second time parameter corresponding to.
- the STA 1520 may use the specific AC through the EDCA. May transmit a frame corresponding to the AP 1510.
- the STA 1520 may display a frame corresponding to the specific AC. It may not transmit.
- the STA 1520 Even if the STA 1520 according to the present embodiment acquires a transmission opportunity (TXOP) for transmission of a frame included in a specific AC through EDCA, the second time parameter of the specific AC exceeds the first time parameter of the specific AC. If so, the STA 1520 may give up transmission of a frame included in a specific AC that has acquired a transmission opportunity (TXOP).
- TXOP transmission opportunity
- the STA 1520 may transmit a transmission opportunity (TXOP) for a specific AC (eg, AC VO) through a competition-based EDCA with another STA (not shown) and the AP 1510. )
- TXOP transmission opportunity
- the first uplink frame UL # 1 of FIG. 15 may be understood as a frame included in the AC VO of FIG. 12.
- the STA 1520 may have a second time parameter maintained for the AC VO and a first time parameter corresponding to the preset allowed time (admitted_time) for the specific AC (ie, AC VO). By comparing, it may be determined whether to transmit the first UL frame UL # 1.
- the value of the second time parameter held for the specific AC ie, AC VO
- the value of the second time parameter held for the specific AC is smaller than the value of the first time parameter.
- the STA 1520 of FIG. 15 may transmit the first uplink frame UL # 1 to the AP 1510 through EDCA.
- the first uplink frame UL # 1 may be a QoS data frame or a QoS null frame.
- the second section T1 to T2 may be understood as a section required for receiving the acknowledgment frame ACK # 1 for the first uplink frame UL # 1.
- the third section T3 to T4 may be SIFS.
- the STA 1520 may or may not receive an acknowledgment frame ACK # 1 (that is, the first uplink frame UL # 1).
- a second time parameter corresponding to the usage time (used_time) of a specific AC ie, AC VO
- AC VO usage time
- the STA 1520 adds the MPDUExchangeTime for the first uplink frame UL # 1 to the usage time (used_time ') of the existing specific AC (ie, AC VO) based on Equation 4,
- the second time parameter of AC (ie, AC VO) can be newly calculated.
- the value of MPDUExchangeTime for the first uplink frame UL # 1 may be a first processing time required for transmission of the first uplink frame UL # 1 (that is, T1 to T2 of FIG. 15),
- the second processing time (ie, T2 to T3 of FIG. 15) and SIFS (that is, T3 to T4 of FIG. 15) required for reception of the acknowledgment frame ACK # 1 may be set.
- the AP 1510 and the STA 1520 may wait.
- the STA 1520 may receive a trigger frame TF for transmitting a multi-user uplink from the AP 1510.
- the trigger frame TF may include an uplink resource unit for the STA 1520.
- the sixth section T6 to T7 may be SIFS.
- the STA 1520 may transmit the trigger-based uplink frame UL # 2 to the AP 1510 in response to the trigger frame TF.
- the trigger based uplink frame UL # 2 may be understood as a frame included in the AC VO of FIG. 12.
- a second time parameter corresponding to the usage time (used_time) of a specific AC may not be newly calculated.
- the STA 1520 may not add the MPDUExchangeTime for the trigger-based uplink frame UL # 2 to the existing usage time (used_time ') of the specific AC (ie, AC VO) based on Equation 4.
- MPDUExchangeTime of Equation 4 may not be considered.
- the trigger-based uplink frame UL # 2 allows a second time parameter corresponding to an existing usage time (used_time ') of a specific AC (ie, AC VO) and allowance of a specific AC (ie, AC VO). It can be transmitted regardless of the result of the comparison of the value of the first time parameter corresponding to the time admitted_time (ie, even if the second time parameter exceeds the first time parameter).
- the eighth section T8 to T9 may be SIFS.
- the STA 1520 may receive an acknowledgment frame ACK # 2 from the AP 1510 for indicating successful reception of the trigger based uplink frame UL # 2.
- the section corresponding to MPDUExchangeTime of Equation 4 may be understood as the seventh section (T7 ⁇ T8) to the ninth section (T9 ⁇ T10). have.
- the seventh period (T7 ⁇ T8) to the seventh period in the existing use time (used_time ') of a specific AC for example, AC VO
- the values corresponding to the nine sections T9 to T10 are not summed.
- a value (ie, MPDUExchangeTime) corresponding to the seventh period T7 to T8 to the ninth period T9 to T10 is exemplary, and is limited thereto. It will be understood.
- MPDUExchangeTime of Equation 4 may indicate a time corresponding to a section associated with transmission of the trigger-based uplink frame UL # 2.
- a value obtained by adding SIFS to a seventh period T7 to T8 to a ninth period T9 to T10 is set to MPDUExchangeTime of Equation 4. It will be understood.
- response frame ACK # 2 of FIG. 15 may be a frame transmitted to the plurality of STAs to inform the successful reception of the plurality of uplink frames transmitted from the plurality of STAs.
- the AP 1510 and the STA 1520 may wait.
- the STA 1520 receives a transmission opportunity (TXOP) for a specific AC (eg, AC VO) through a competition-based EDCA with another STA (not shown) and the AP 1510.
- TXOP transmission opportunity
- the third uplink frame UL # 3 of FIG. 15 may be understood as a frame included in the AC VO of FIG. 12.
- the STA 1520 may determine a second time parameter and a specific AC (ie, AC VO) of a specific AC newly calculated during the transmission of the first uplink frame UL # 1.
- the first time parameter corresponding to the allowed time (admitted_time) of the AC VO may be compared to determine whether to transmit the third uplink frame UL # 3.
- 16 is a flowchart illustrating a method of transmitting a frame in a WLAN system performed by a wireless terminal according to an embodiment of the present invention.
- the user STA may determine whether a frame to be transmitted is a frame to be transmitted through EDCA.
- operation S1610 if it is determined that the frame to be transmitted by the user STA is not a frame to be transmitted through the EDCA, operation S1620 may be performed.
- the frame to be transmitted may be understood as a trigger-based frame that is a response to a trigger frame for multi-user uplink (MU UL) transmission received from the AP.
- MU UL multi-user uplink
- step S1620 when the trigger-based frame is transmitted, the user STA sends a request time for the trigger-based frame to the second time parameter of the specific AC indicating the existing usage time (used_time ') associated with the specific AC according to Equation 4. May not add up.
- the second time parameter corresponding to the usage time (used_time) of the specific AC is not updated, and the user STA may maintain a value corresponding to the existing usage time (used_time ') of the specific AC. have.
- Trigger-based frame may be transmitted in response to the received trigger frame.
- operation S1610 if it is determined that the frame to be transmitted by the user STA is a frame to be transmitted through the EDCA, operation S1630 may be performed.
- the user STA may compare the first time parameter for the allowable time of the specific AC of the frame to be transmitted through the EDCA and the second time parameter for the use time of the specific AC.
- the user STA may be understood as a wireless terminal obtaining a transmission opportunity for a frame of a specific AC through competition-based EDCA with other STAs and APs.
- step S1630 if the second time parameter maintained at the existing value for the specific AC does not exceed the first time parameter of the specific AC, step S1640 may be performed.
- the user STA may transmit a frame of a specific AC to the AP through EDCA.
- the user STA may use the usable time of the specific AC.
- the second time parameter corresponding to may be newly calculated (or updated).
- the request time for a frame of a specific AC through EDCA may indicate the first processing time required for transmission of a sequence included in a frame to be transmitted via EDCA, the reception of an acknowledgment frame for a frame to be transmitted via EDCA. It may be a sum of time required for second processing time and short-inter frame spacing (SIFS) required.
- SIFS short-inter frame spacing
- step S1630 if the second time parameter maintained at the existing value for the specific AC exceeds the first time parameter of the specific AC, step S1650 may be performed.
- step S1650 the user STA may not transmit the frame through the EDCA.
- a procedure performed based on an EDCA and a procedure performed based on a trigger frame may be treated as separate independent procedures.
- a case where the transmission of the trigger-based frame fails may be reduced due to the effect of the procedure performed based on the EDCA.
- the failure of the EDCA-based transmission may be reduced due to the effect of the procedure performed based on the trigger frame.
- a WLAN system having improved performance may be provided.
- 17 is a block diagram illustrating a wireless terminal to which the present embodiment can be applied.
- a wireless terminal may be an STA that may implement the above-described embodiment and may be an AP or a non-AP STA.
- the wireless terminal may correspond to the above-described user or may correspond to a transmitting terminal for transmitting a signal to the user.
- the AP 1700 includes a processor 1710, a memory 1720, and a radio frequency unit 1730.
- the RF unit 1730 may be connected to the processor 1710 to transmit / receive a radio signal.
- the processor 1710 may implement the functions, processes, and / or methods proposed herein. For example, the processor 1710 may perform an operation according to the above-described exemplary embodiment. The processor 1710 may perform an operation of the AP disclosed in the present embodiment of FIGS. 1 to 16.
- the non-AP STA 1750 includes a processor 1760, a memory 1770, and an RF unit 1780.
- the RF unit 1780 may be connected to the processor 1760 to transmit / receive a radio signal.
- the processor 1760 may implement the functions, processes, and / or methods proposed in the present embodiment.
- the processor 1760 may be implemented to perform the non-AP STA operation according to the present embodiment described above.
- the processor 1760 may perform an operation of the non-AP STA disclosed in the present embodiment of FIGS. 1 to 16.
- Processors 1710 and 1760 may include application-specific integrated circuits (ASICs), other chipsets, logic circuits, data processing devices, and / or converters to convert baseband signals and wireless signals to and from each other.
- the memories 1720 and 1770 may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and / or other storage devices.
- the RF unit 1730 and 1780 may include one or more antennas for transmitting and / or receiving a radio signal.
- the above-described technique may be implemented as a module (process, function, etc.) for performing the above-described function.
- the module is stored in the memories 1720 and 1770 and may be executed by the processors 1710 and 1760.
- the memories 1720 and 1770 may be inside or outside the processors 1710 and 1760, and may be connected to the processors 1710 and 1760 by various well-known means.
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Abstract
Description
Claims (10)
- 무선단말에 의해 수행되는 무선랜 시스템에서 프레임을 송신하는 방법에 있어서,상기 무선단말의 송신을 위해 사용된 시간을 지시하는 시간 파라미터와 미리 설정된 허용시간(admitted time)을 비교하여, EDCA(Enhanced Distributed Channel Access)를 통해 제1 프레임을 AP(access point)로 송신하는지 여부를 결정하는 단계;상기 시간 파라미터에 상기 제1 프레임의 송신을 위한 제1 요구시간을 합산하는 단계;다중 사용자 상향링크(multi-user uplink) 송신을 위한 트리거 프레임을 상기 AP로부터 수신하는 단계; 및상기 트리거 프레임에 대한 응답으로 송신되는 제2 프레임을 위한 데이터 처리를 수행하되, 상기 제2 프레임의 송신을 위한 제2 요구시간은 상기 시간 파라미터에 합산되지 않는, 단계를 포함하는 방법.
- 제1 항에 있어서,상기 합산된 시간 파라미터와 상기 허용시간을 비교하여, 상기 EDCA를 통해 제3 프레임을 상기 AP로 송신하는지 여부를 결정하는 단계; 및상기 합산된 시간 파라미터에 상기 제3 프레임의 송신을 위한 제3 요구시간을 합산하는 단계를 더 포함하는 방법.
- 제1 항에 있어서,상기 제1 프레임을 AP로 송신하는지 여부를 결정하는 단계는,상기 시간 파라미터가 상기 허용시간을 초과하면, 상기 제1 프레임을 송신하지 않는 단계; 및상기 시간 파라미터가 상기 허용시간을 초과하지 않으면, 상기 제1 프레임을 송신하는 단계를 더 포함하는 방법.
- 제1 항에 있어서,상기 제2 프레임은 상기 합산된 시간 파라미터가 상기 허용시간을 초과하는지 여부와 관계 없이 송신되는 프레임인 방법.
- 제1 항에 있어서,상기 허용시간은 세션(session) 형성을 위해 상기 무선단말에 의해 송신된 ADDTS(add traffic stream) 요청 프레임에 대한 응답으로 상기 AP로부터 수신된 ADDTS 응답 프레임에 포함된 TSPEC 요소(traffic specification)를 기반으로 설정되는 값인 방법.
- 제1 항에 있어서,상기 제1 요구시간은 상기 제1 프레임에 포함된 시퀀스의 송신을 위해 요구되는 제1 처리시간, 상기 제1 프레임에 대한 응신 프레임의 수신을 위해 요구되는 제2 처리시간 및 SIFS(Short-Inter Frame Spacing)에 상응하는 시간을 합산한 시간인 방법.
- 제1 항에 있어서,상기 제1 요구시간은 상기 제1 프레임의 송신에 대한 응답으로 상기 AP로부터 응신 프레임이 수신되는지 여부와 관계 없이 상기 시간 파라미터에 합산되는 시간인 방법.
- 제1 항에 있어서,상기 제1 요구시간은 상기 제1 프레임의 송신 시도 이후에 상기 시간 파라미터에 합산되는 값인 방법.
- 제1 항에 있어서,상기 제2 요구시간은 상기 제2 프레임에 포함된 시퀀스의 송신을 위해 요구되는 제3 처리시간, SIFS(Short-Inter Frame Spacing)에 상응하는 시간 및 상기 제2 프레임에 대한 응신 프레임의 수신을 위해 요구되는 제4 처리시간을 합산한 시간인 방법
- 무선랜 시스템에서 프레임을 송신하는 방법을 이용하는 무선단말에 있어서, 상기 무선단말은,무선신호를 송수신하는 송수신기; 및상기 송수신기에 연결되는 프로세서를 포함하되, 상기 프로세서는, 상기 무선단말의 송신을 위해 사용된 시간을 지시하는 시간 파라미터와 미리 설정된 허용시간(admitted time)을 비교하여, EDCA(Enhanced Distributed Channel Access)를 통해 제1 프레임을 AP(access point)로 송신하는지 여부를 결정하도록 구현되고,상기 시간 파라미터에 상기 제1 프레임의 송신을 위한 제1 요구시간을 합산하도록 구현되고,다중 사용자 상향링크(multi-user uplink) 송신을 위한 트리거 프레임을 상기 AP로부터 수신하도록 구현되고,상기 트리거 프레임에 대한 응답으로 송신되는 제2 프레임을 위한 데이터 처리를 수행하도록 구현되되, 상기 제2 프레임의 송신을 위한 제2 요구시간은 상기 시간 파라미터에 합산되지 않는 무선단말.
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