KR102216010B1 - Method and apparatus for transmitting and receiving data based on aggressive spatial reuse - Google Patents

Abstract

A method and apparatus for transmitting and receiving data based on ASR are disclosed. The wireless data transmission method of a first wireless device (mobile terminal) is a step of generating an aggressive spatial reuse (ASR) list by transmitting a disruptive request to send (dRTS) frame, and channel access to a specific channel based on an ASR backoff procedure. Performing, transmitting an srDATA frame to a second wireless device in the specific channel based on the ASR list; And receiving an srACK (acknowledgement) frame in response to the srDATA frame from the second wireless device, wherein the specific channel is a channel through which a third wireless device transmits and receives data frames, and the srDATA frame and The data frame is transmitted on the specific channel at a specific time, and the ASR list may be information on a wireless device that does not collide with the data frame when the first wireless device transmits the srDATA frame and receives the srACK frame. have.

Description

ASR-based wireless data transmission method and apparatus {METHOD AND APPARATUS FOR TRANSMITTING AND RECEIVING DATA BASED ON AGGRESSIVE SPATIAL REUSE}

The present invention relates to wireless communication, and more particularly, to a method and apparatus for transmitting data over a wireless channel.

Compared to the early days when a wireless LAN card was inserted into a notebook in the late 90s, wireless LAN is now basically installed in various smart devices such as smart phones and smart pads, including notebooks and PCs. Since it is not only used in various devices, but also has various uses, Internet access through a wireless LAN is basic, and various services based on wireless LAN such as file and data transfer between devices, and high-definition video streaming are used in real life. In recent years, the use of wireless LAN is expanding to unimaginable uses, such as protecting home safety based on wireless LAN, controlling home appliances as well as externally, and contributing to lowering customers' electricity bills in connection with power companies.

The IEEE 802.11ac standard enables gigabit transmission rates in the 5GHz band based on wireless LAN. In addition to ultra-high-speed transmission, various service scenarios using wireless LAN are possible. In particular, standardization of IEEE 802.11ah and IEEE 802.11af technologies that extend wireless LAN coverage by using a frequency band below 1GHz or by sharing the frequency band used by TVs. Is actively underway. In addition, IEEE 802.11ai standardization is in progress to reduce wireless LAN access time in congested areas.

IEEE 802.11af is a technology used by wireless LANs based on a database based on an idle TV band. 5GHz IEEE 802.11ac PHY layer (physical layer) is basically used by down-clocking. In the case of IEEE 802.11af, it is greatly affected by the frequency regulation on the TV idle band, and the FCC recently announced a reverse auction for the TV idle band, and the result is expected to be decided in 2015. The ear is attention.

IEEE 802.11ah enables a wide area wireless LAN service by using an increase in the radio wave reach based on the characteristics of a frequency band below 1 GHz. In addition, it supports a number of low-power sensors operating in a power saving mode, and can be used for cellular offloading. Preamble and beacon signals are designed to be suitable for these service applications, and TIM (Traffic Indication MAP) is also designed in a hierarchical structure.

IEEE 802.11ai is a MAC technology for reducing wireless LAN access time. The access time in congestion is shortened by filtering the probe response in active scanning, and the access time is shortened by designing a new discovery frame and simplifying the security level.

A first object of the present invention is to provide a method for transmitting wireless data based on ASR (aggressive spatial reuse).

A second object of the present invention is to provide an apparatus for transmitting wireless data based on ASR.

The wireless data transmission method of a first wireless device (mobile terminal) according to an aspect of the present invention for achieving the first object of the present invention described above is by transmitting a disruptive request to send (dRTS) frame to achieve aggressive spatial reuse (ASR). Generating a list, performing channel access to a specific channel based on an ASR backoff procedure, and transmitting an srDATA frame from the specific channel to a second wireless device based on the ASR list; And receiving an srACK (acknowledgement) frame in response to the srDATA frame from the second wireless device, wherein the specific channel is a channel through which a third wireless device transmits and receives data frames, and the srDATA frame and The data frame is transmitted on the specific channel at a specific time, and the ASR list may be information on a wireless device that does not collide with the data frame when the first wireless device transmits the srDATA frame and receives the srACK frame. have. The ASR backoff procedure includes determining an ASR backoff time by selecting a random number N (N is a natural number) within an ASR contention window, measuring noise power as the ASR backoff time decreases, and measuring the ASR backoff time. It may include performing the channel access when the noise power does not exceed a threshold value until the off time becomes zero. When the first transmission end time of the srDATA frame and the second transmission end time of the data frame are set equally, the srDATA frame is zero padded data when the second transmission end time is longer than the first transmission end time It may include. The information on the second transmission end time may be obtained based on a duration field included in a request to send (RTS) frame transmitted by the third wireless device. The ASR list may be updated by deleting the specific wireless device when the first wireless device does not receive a response frame more than a certain number of times from the specific wireless device that transmitted the frame. The step of generating an ASR list by transmitting the dRTS frame by the first wireless device includes determining whether a collision has occurred in a data frame transmitted from another wireless device due to the dRTS frame, and no collision occurs in the data frame. If not, including the other wireless device in the ASR list.

In a first wireless device for transmitting wireless data according to an aspect of the present invention for achieving the second object of the present invention described above, the first wireless device comprises: a radio frequency (RF) for transmitting and receiving a radio signal. part; And a processor selectively connected to the RF unit to operate, wherein the processor transmits a disruptive request to send (dRTS) frame to generate an aggressive spatial reuse (ASR) list, and a specific channel based on the ASR backoff procedure It is implemented to perform channel access, transmit an srDATA frame to a second wireless device on the specific channel based on the ASR list, and receive an srACK (acknowledgement) frame in response to the srDATA frame from the second wireless device. , The specific channel is a channel through which a third wireless device transmits and receives a data frame, the srDATA frame and the data frame are transmitted on the specific channel at a specific time point, and the ASR list includes the first wireless device as an srDATA frame. When transmitting and receiving an srACK frame, it may be information on a wireless device that does not collide with the data frame. In the ASR backoff procedure, the ASR backoff time is determined by selecting a random number N (N is a natural number) in the ASR contention window, and noise power is measured as the ASR backoff time is reduced, and the ASR backoff time When the noise power does not exceed a threshold value until the value reaches zero, the channel access may be performed. When the first transmission end time of the srDATA frame and the second transmission end time of the data frame are set equally, the srDATA frame is zero padded data when the second transmission end time is longer than the first transmission end time It may include. The information on the second transmission end time may be obtained based on a duration field included in a request to send (RTS) frame transmitted by the third wireless device. The ASR list may be updated by deleting the specific wireless device when the first wireless device does not receive a response frame more than a certain number of times from the specific wireless device that transmitted the frame. The processor may be implemented to determine whether a collision has occurred in a data frame transmitted from another wireless device due to the dRTS frame, and to include the other wireless device in the ASR list if there is no collision in the data frame. I can.

As described above, by using the ASR-based wireless data transmission method and apparatus according to an embodiment of the present invention, spatial resources can be more actively recycled than the existing wireless LAN, thereby increasing data transmission efficiency in the wireless LAN.

1 is a conceptual diagram illustrating a channel access method of an STA based on DCF.
2 is a conceptual diagram illustrating a backoff procedure of a plurality of STAs.
3 is a conceptual diagram showing an inter frame space (IFS).
4A, 4B and 4C are conceptual diagrams showing a method of transmitting wireless data according to an embodiment of the present invention.
5 is a conceptual diagram showing an ASR method according to an embodiment of the present invention.
6 is a conceptual diagram illustrating a method of transmitting wireless data based on ASR according to an embodiment of the present invention.
7 is a conceptual diagram illustrating a method of transmitting wireless data based on ASR according to an embodiment of the present invention.
8 is a conceptual diagram illustrating a method of transmitting wireless data based on ASR according to an embodiment of the present invention.
9 is a conceptual diagram showing a method of generating an ASR list according to an embodiment of the present invention.
10 is a block diagram showing a wireless device to which an embodiment of the present invention can be applied.

In the present invention, various modifications may be made and various embodiments may be provided, and specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to a specific embodiment, it is to be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention. In describing each drawing, similar reference numerals have been used for similar elements.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. These terms are used only for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. The term and/or includes a combination of a plurality of related listed items or any of a plurality of related listed items.

When a component is referred to as being "connected" or "connected" to another component, it is understood that it is directly connected to or may be connected to the other component, but other components may exist in the middle. Should be. On the other hand, when a component is referred to as being "directly connected" or "directly connected" to another component, it should be understood that there is no other component in the middle.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof, does not preclude in advance.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings. Hereinafter, the same reference numerals are used for the same elements in the drawings, and duplicate descriptions for the same elements are omitted.

Hereinafter, in the embodiment of the present invention, the STA includes a medium access control (MAC) and a physical layer interface for a wireless medium in accordance with the IEEE (Institute of Electrical and Electronics Engineers) 802.11 standard. As a functional medium of, it may be used in a broad sense to include both an access point (AP) and a non-AP station (STA).

The STA includes a mobile terminal, a wireless device, a wireless transmit/receive unit (WTRU), a user equipment (UE), a mobile station (MS), and a mobile subscriber unit ( Mobile Subscriber Unit) or simply user.

1 is a conceptual diagram illustrating a channel access method of an STA based on DCF.

In general, in a channel access method based on a distributed coordination function (DCF), when a medium is not in use for more than a DCF inter frame space (DIFS) period (that is, when the channel is idle during DIFS), the STA cannot transmit. An impending MAC protocol data unit (MPDU) can be transmitted. When the STA determines that the medium is in use by the carrier sensing mechanism, the STA can determine the size of the contention window (CW) by using a random backoff algorithm and perform a backoff procedure. have. The STA configures the CW to perform the backoff procedure and selects a random time slot within the CW. The selected time slot is called the backoff time. An STA that selects a relatively short backoff time among the backoff times selected by each of the plurality of STAs may preferentially access the medium than the STA that selects the long backoff time. The remaining STAs may stop the remaining backoff time and wait until transmission of the STA transmitting the frame is completed. After the frame transmission of the STA is completed, the remaining STAs may compete with the remaining backoff time to obtain a medium.

That is, when the STA accesses the channel using the DCF, the STA may detect the channel state for a predetermined time. Specifically, when the channel is idle during DIFS, the STA attempts to transmit after a random backoff time. Such a DCF-based transmission method serves to prevent a collision occurring when a plurality of STAs simultaneously transmit frames, thereby avoiding collision.

The random backoff time is the time the STA waits before transmitting the frame after the channel waits for a predetermined time (eg, DIFS). The STA may determine the CW based on the minimum CW time CWmin and the maximum CW time CWmax. The STA may calculate the backoff time based on the determined CW.

2 is a conceptual diagram illustrating a backoff procedure of a plurality of STAs.

Referring to FIG. 2, a backoff slot may occur after a medium is determined to be idle for a DIFS period. If the media activity is not detected after the DIFS period, the STA may reduce the backoff time based on aSlotTime. If it is determined that the medium is in use during the backoff slot, the STA may not reduce the backoff time. Frame transmission of the STA may be performed when the configured backoff timer becomes 0.

In addition, the DCF transmission method may use an RTS/CTS access mode in which a control frame (request to send (RTS) frame, clear to send (CTS) frame) is exchanged before transmitting a data frame to occupy a channel in advance. This method can reduce channel waste by replacing collisions that may occur when the STA transmits data frames with collisions caused by relatively short control frames.

The MAC layer may use a point coordination function (PCF) as another method for a plurality of STAs to share a wireless medium. In the case of the aforementioned DCF, since it is based on a carrier sense multiple access (CSMA)/collision avoid (CA) scheme, real-time transmission of data transmitted between the STA and the AP cannot be guaranteed. On the other hand, PCF is a contention-free transmission method, and can be used as a method to ensure quality of service (QoS) when transmitting real-time data. PCF, also referred to as a contention-free transmission service, does not exclusively use the entire transmission period of the medium, but can be used alternately with the contention-based service of the DCF method. The PCF may control the authority for each STA to occupy the medium by using a polling method by a point coordinator implemented in the AP of the BSS. By setting PIFS, an inter-frame space (IFS) in the PCF, to a value smaller than DIFS, an IFS of DCF, priority can be given over DCF when transmitting a frame. IFS indicates an interval between frames and may be used to set a priority for an STA to access a medium. IFS can be specifically defined as follows.

3 is a conceptual diagram showing an inter frame space (IFS).

Referring to FIG. 3, an interval between two frames may be referred to as an IFS. The STA may determine whether a channel is used during a predetermined time period of the IFS using the carrier detection method. The MAC layer using DCF defines various IFSs. Priority of the STA occupying the wireless medium may be determined by the IFS. The interval between frames according to the IFS type is as follows.

(1) SIFS (short inter frame symbol): Used when transmitting RTS/CTS, ACK frames. Highest priority

(2) PIFS (PCF IFS): Used for PCF frame transmission

(3) DIFS(DCF FIS): Used for DCF frame transmission

(4) EIFS (extended IFS): Used only when a frame transmission error occurs, not a fixed interval

When a plurality of STAs use only DCF as a method for sharing a wireless medium in the MAC layer, various problems may occur. For example, in the case of using DCF, when a plurality of STAs simultaneously attempt to perform initial access to an AP, a lot of collisions have occurred between the plurality of STAs. In addition, since there is no concept of transmission priority in DCF, quality of service (QoS) for traffic data transmitted from the STA cannot be guaranteed. To solve this problem, 802.11e defined a new coordination function, a hybrid coordination function (HCF), to improve the channel access performance of the existing DCF and HCF. HCF defines two channel access methods similar to those defined in the existing 802.11 MAC, HCCA (HCF controlled channel access) and EDCA (enhanced distributed channel access).

In EDCA and HCCA, a traffic category, which is a transmission priority, can be defined, and the priority for accessing a channel can be determined based on this. That is, channel access priority according to the type of traffic data may be determined by defining CW and IFS with each other according to the category of traffic data transmitted from the STA.

For example, when the traffic data is email, the data may be assigned to a low priority class. As another example, when the traffic data is voice communication through a wireless LAN, since real-time data transmission is required, the traffic data may be allocated to a high transmission priority class to perform channel access.

When EDCA is used, traffic data having a high priority may have more chances to be transmitted relative to traffic data having a low priority. In addition, on average, an STA having high priority traffic may have less waiting time than an STA having low priority traffic before transmitting a packet. In EDCA, transmission priority is implemented by allocating a shorter CW to higher priority traffic than lower priority traffic, and by allocating an argument inter-frame space (AIFS) that is shorter than IFS, which is a frame interval defined in DCF. Can be. In addition, the EDCA may allow the STA to access the channel without contention during a period called TXOP (Transmit Opportunity). The STA may transmit as many packets as possible during the specified TXOP period as long as the maximum period of the TXOP is not exceeded. If one frame is too long to be transmitted during one TXOP, it can be cut into smaller frames and transmitted. The use of TXOP can reduce a situation in which an STA having a low transmission rate, which is a problem with the existing 802.11 DCF MAC, excessively occupies a channel.

In the existing IEEE 802.11-based wireless LAN, data collision occurs because a plurality of STAs or APs competently transmit data. To prevent this, the STA that wants to transmit data checks whether the corresponding channel is used by other STAs, and transmits the frame only when it is confirmed that no one is using the corresponding channel, thereby avoiding collisions between frames. Guaranteed.

However, since a distance between STAs is separated by a predetermined distance or more, data may be normally received without collision between frames even when frames are transmitted and received between different APs and STAs at the same time. When using the case where no collision between frames occurs, the overall data transmission efficiency in the wireless LAN can be increased.

In an embodiment of the present invention, when another node (STA or AP) occupies a corresponding channel to transmit a frame, it is possible to check whether a collision between frames occurs and transmit the frame. In other words, it is possible to check a case in which a frame is transmitted and does not cause a collision with a frame transmitted and received by another node because it is spatially separated from a node transmitting and receiving the current frame, and transmits the frame. By using such a frame transmission method, it is possible to increase overall data transmission efficiency in a wireless LAN.

For example, in order to actively recycle space, when a certain STA transmits data, a collision is artificially caused, and an artificial collision does not affect data transmission.

In an embodiment of the present invention, unlike a conventional WLAN, a specific STA and/or other STAs adjacent to a specific AP and other APs may simultaneously transmit and receive data on the same channel. Hereinafter, in an embodiment of the present invention, the operation of the AP and the STA are classified for convenience of description, but as described above, the STA includes both an access point (AP) and a non-AP STA (Non-AP Station) in a broad sense. It can be used as a meaning. For example, in the case of wifi-direct, all STAs may be interpreted as non-AP STAs. That is, hereinafter, the STAs posted in the embodiment of the present invention may be interpreted as either an access point (AP) or a non-AP station (non-AP STA).

4A, 4B, and 4C are conceptual diagrams illustrating a frame transmission and reception method according to an embodiment of the present invention.

4A shows the locations of STA A 410, STA B 420, STA C 430, STA D 440, and STA X 400. Hereinafter, according to an embodiment of the present invention, a method for transmitting and receiving data through the same channel by a specific STA determining whether data collides even when data transmission and reception between other STAs is performed according to the location of a specific STA Post about.

Referring to FIG. 4B, STA C 430 posts a case in which STA X 400 transmits a dRTS (request to send) frame while transmitting and receiving data frames with STA D 440. As described above, in order to determine whether a collision for a data frame occurs during transmission and reception of a data frame between STA C 430 and STA D 440, the transmitted frame is transmitted by the STA X 400 in a disruptive RTS. It can also be expressed in terms of (dRTS) frame (or poke RTS frame).

The dRTS frame transmitted by the STA X 400 may collide with the data frame transmitted by the STA C 430. Due to collision, STA C 430 may not be able to receive an ACK frame from STA D 440 in response to a data frame.

When the STA C 430 does not receive an ACK for the transmitted data frame, the STA C 430 may retransmit the data frame. The MAC header of the retransmitted data frame may set the RET field. STA X (400) can determine a situation where STA D (440) has to transmit an ACK to STA C (430) but could not send it, and when STA C (430) retransmits a data frame, it may not transmit a dRTS frame. . STA D 440 may transmit an ACK to STA C 430 for the data frame retransmitted by STA C 430. The STA X 400 may determine that transmission and reception of ASR-based data is impossible based on this procedure.

FIG. 4C publishes a case where the dRTS frame transmitted by STA B 420 does not collide with the data frame transmitted by STA C 430. In this case, STA D 440 may transmit an ACK frame in response to a data frame received from STA C 430. That is, when the STA is separated from another STA by a predetermined distance or more, the dRTS frame has a negligible effect, so that the data frame transmitted by the STA C 430 may be properly received without being broken. Unlike the case of STA X400, STA D 440 may transmit an ACK to STA C 430 after SIFS. When STA B 420 receives the ACK transmitted by STA D 440 or when it is confirmed that STA C 430 does not retransmit the data frame, it may determine that it is in an area where ASR-based data transmission and reception is possible. I can. Hereinafter, in the embodiment of the present invention, for convenience of description, it is assumed that an ACK frame other than a NACK frame is received in response to a data frame.

As described above, the STA or AP that intends to perform the ASR may determine whether or not the ASR can be performed through the relationship with the neighboring AP and/or the neighboring STA. For example, an STA wishing to perform ASR may generate an ASR list to which an ASR strategy can be applied based on a relationship with a neighboring AP and/or a neighboring STA. The ASR list may include information related to an STA and/or an AP capable of performing ASR by the STA. A method of generating the ASR list will be described later.

5 is a conceptual diagram illustrating a channel congestion back-off method according to an embodiment of the present invention.

In FIG. 5, a case where both STA B 520 and STA E 550 can use ASR and transmit an srDATA frame is disclosed. The term srDATA frame may be used to distinguish a data frame transmitted and received based on the ASR method from an existing data frame.

Referring to FIG. 5, for example, it may be assumed that STA B 520 and STA E 550 are both capable of ASR and attempt to simultaneously transmit an srDATA frame to STA A 510. As described above, STA A 510 may also be interpreted as an AP. In this case, a collision may occur between the srDATA frame transmitted by the STA B 520 and the STA E 550.

That is, when a collision occurs between the first srDATA frame transmitted by STA B 520 to STA A 510 and the second srDATA frame transmitted by STA E 550 to STA A 510, STA A 510 ) May not receive the first srDATA frame and the second srDATA frame.

In order to prevent such a collision problem between srDATA frames, even when a frame is transmitted based on ASR, channel resources may be obtained based on a back-off procedure. Even when a frame is transmitted based on the ASR, a back-off procedure may be performed differently from a conventional back-off procedure.

The conventional random back-off procedure operates when a channel is in an idle state, but the ASR-based back-off procedure according to an embodiment of the present invention can operate even when a channel is in a busy state.

The ASR-based back-off procedure can be specifically performed through the following procedure. When described based on the STA, the STA randomly selects one number N among the numbers in the ASR-contention window in order to perform the ASR-based back-off procedure. In the ASR-based back-off procedure, an ASR contention window can be defined as a contention window, and an ASR backoff time can be determined by selecting a random number N within the corresponding ASR contention window.

It stores information about the current noise power (Pn).

Without considering the channel state, the ASR backoff time can be reduced, and information on the current noise power can be updated as the ASR backoff time is reduced.

If, as the ASR backoff time decreases, the measured current noise power exceeds a certain threshold, another STA wins the ASR-based back-off competition and is considered to be transmitting an ASR-based frame, and the STA The frame may not be transmitted.

Conversely, when the current noise power measured when the ASR backoff time decreases and becomes 0 and the ASR backoff time does not exceed a certain threshold value, the STA may transmit the ASR frame.

That is, according to an embodiment of the present invention, a frame transmitted by another STA or another AP is detected in a channel in which the STA operates, and it is possible to determine whether to transmit the ASR frame according to whether the noise power is equal to or greater than a predetermined value.

<Table 1>

This ASR-based back-off procedure may be used to transmit an ASR frame (eg, an srDATA frame and a dRTS frame).

6 is a conceptual diagram illustrating a method of transmitting and receiving data based on ASR according to an embodiment of the present invention.

Referring to FIG. 6, while STA C 630 transmits a data frame to STA D 640, STA B 620 may transmit an srDATA frame to STA A 610. STA B 420 and STA C 430 may also be interpreted as APs.

STA B 620 may simultaneously access a channel through which STA C 430 and STA D 640 transmit and receive frames through the aforementioned ASR-based back-off procedure. STA B 620 may perform ASR to transmit the srDATA frame to STA A 610 without causing a collision with respect to the data frame transmitted by STA C 630.

In this case, STA A 610 responds with an srACK frame to the srDATA frame transmitted by STA B 620, and collisions may occur with data frames transmitted by other APs and/or STAs in the corresponding channel.

For example, while STA C 630 transmits a data frame to STA D 640, STA B 620 may transmit an srDATA frame to STA A 610. If, the transmission time of the srDATA frame transmitted by STA B 620 may be terminated relatively faster than the transmission time of the data frame of STA C (630). In this case, srACK transmitted by STA A 610 to STA B 620 may collide with a data frame transmitted by STA C 630. In this case, STA B 620 cannot receive the srACK transmitted from STA A 610. In order to solve this problem, STA B 420 must be able to transmit the size of the srDATA frame according to the size of the data frame transmitted by STA C 430.

Therefore, according to an embodiment of the present invention, in order to solve this problem, the time when STA C 430 ends transmission of the data frame and the time when STA B 420 ends transmission of the srDATA frame can be set equally. Should be.

7 is a conceptual diagram illustrating a method of transmitting and receiving data based on ASR according to an embodiment of the present invention.

In FIG. 7, a method of setting the same time when the STA and/or AP transmitting the srDATA frame ends transmission of the srDATA frame and the time when the other STA and/or other AP transmitting the data frame ends transmission of the data frame. It discloses about.

Referring to FIG. 7, so that the second end time when the transmission of the srDATA frame ends and the second end time when the transmission of the data frame transmitted by the STA C 730 ends is the same as the STA B 720 performing the ASR. Can be set.

STA B 720 may set the same size of the srDATA frame transmitted by STA B 720 and the data frame transmitted by STA B 720 in order to set the second end time to be the same as the first end time. . For example, STA B 720 considers the modulation and channel coding method, etc., so that the time at which the transmission of the data frame ends is the same as the time at which the transmission of the ASR data frame ends. You can decide when to send. By using this method, when STA A 710 transmits an srACK frame for an srDATA frame, it is possible to prevent collision with a frame transmitted by another AP and/or another STA.

Alternatively, in order to ensure that the time at which the transmission of the data frame ends is the same as the time at which the transmission of the srDATA frame ends, the STA B 720 transmits the data frame transmitted by the STA C 730 before transmitting the data frame. Before transmission, information on the transmission end time of the data frame of the STA C 730 may be obtained based on the duration field of the transmitted RTS frame. STA B 720 may set the same transmission end time of the srDATA frame based on information about the transmission end time of the data frame of STA C 730. For example, the srDATA frame may perform zero padding to set the same transmission end time. For example, zero padding (or null padding) may be implemented in the MAC layer and may be implemented in the form of an aggregated MAC protocol data unit (A-MPDU). MPDU is aggregated to transmit a data frame, and null padding may transmit only the subframe header of the A-MPDU.

By using this method, the srACK frame transmitted by STA A 710 may not collide with the data frame transmitted by STA C 730 in time. When the srACK frame temporally collides with the data frame transmitted by the STA C 730, interference may occur with each other, and an error may occur in data reception. Therefore, by using this method, STA B 720 can receive an srACK frame from STA A 710 without interference of data frames.

However, based on this method, even when STA A 710 transmits an srACK frame, an STA or another AP (eg, STA D 740) different from the srACK frame transmitted by STA A 710 transmits srACK frames may collide.

8 is a conceptual diagram illustrating a method of transmitting and receiving data based on ASR according to an embodiment of the present invention.

In FIG. 8, even when a second STA transmits an srACK frame based on the method described above in FIG. 7, a solution method when an ACK frame transmitted by a second STA and an ACK frame transmitted by another STA or another AP collide. Start. When the ACK frame transmitted by the second STA and the ACK frame transmitted by another STA or another AP collide with each other, the ASR procedure may be stopped according to a certain determination.

Referring to FIG. 8, in a situation in which STA C 800 and STA D 850 communicate, a plurality of STAs, such as STA (E), STA (G), and STA (J), are STA (F) and STA, respectively. (H), indicates a case to transmit a frame to the STA (I) based on the ASR. STAs A through I posted in FIG. 8 may be assumed to be STAs located at the locations posted in FIG. 9.

STA C 800 may transmit and receive frames with STA D 850. In this situation, at least one of the STA(E), STA(G), and STA(J) performs an ASR-based random backoff procedure to transfer the srDATA frame to STA(F), STA(H), and STA(I). It may be assumed that transmission is transmitted to at least one of the STAs. As described above, the srDATA frame performs zero padding so that the time when transmission of the data frame transmitted by the STA C 800 is terminated and the time when the transmission of the srDATA frame is terminated may be set equally.

When transmitting the srDATA frame, at least one of the STA(F), STA(H), and STA(I) may transmit the srACK frame in response thereto. This srACK frame may collide with the ACK frame transmitted by the STA D 810.

In order to prevent such a case, the STA and/or the AP may determine whether to perform the ASR procedure based on the ASR list.

9 is a conceptual diagram showing a method of generating an ASR list according to an embodiment of the present invention.

Referring to FIG. 9, when an srACK frame cannot be received in response to an srDATA frame in order to prevent frame collision when performing ASR, a data transmission and reception procedure based on ASR may not be performed.

Hereinafter, in the embodiment of the present invention, it is assumed that the AP transmits the dRTS frame for convenience of description, but the STA may transmit the dRTS frame. In addition, in FIG. 9, for convenience of description, it is assumed that node H, node J, node F, node E, node G, and node I are STAs, but as described above, a specific STA may be interpreted as an AP.

First, STA C 900 to perform ASR may transmit a dRTS frame. In response to the dRTS frame, the STA D 950 may transmit the dCTS frame.

In this case, another STA and/or another AP located in the vicinity of STA C 900 and STA D 950 may receive the dRTS frame and/or dCTS frame. For example, STA (H), STA (J), and STA (F) adjacent to STA C 900 and STA D 950 may receive the dRTS frame and the dCTS frame. In this case, each STA (H), STA (J), and STA (F) transmits an srACK frame even when an srDATA frame is received from one of STA (E), STA (G) and STA (I). I can't. That is, when STA C 900 and STA D 950 perform ASR, the AP or STA that is located within the transmission coverage of STA C 900 and STA D 950 and receives the dRTS frame and dCTS frame Based on data transmission and reception procedures may not be performed.

In addition, an AP or STA that has not received a dRTS frame or a dCTS frame because it is not located within the transmission coverage of STA C 900 and STA D 950 determines whether to receive an srACK response frame for its srDATA frame, Based on data transmission and reception procedures may not be performed.

For example, one of the STA(E), STA(G), and STA(I) may transmit the srDATA frame to the STA(H), STA(J), and STA(F). It may be determined whether or not the srACK frame is received in response to the srDATA frame after a certain time (SIFS) after transmitting the srDATA frame. When the srACK frame is received, data transmission and reception procedures based on the STA and the ASR can be performed.

If, after a certain time (SIFS) after transmitting the ASR data frame, there may be a case where the srACK frame is not received in response to the srDATA frame. This is because, as described above, STA(H), STA(J), and STA(F) are not already configured to respond to srDATA frames of STA(E), STA(G), and STA(I). In this case, the STA may increase the size of the ASR contention window used to perform the ASR back-off procedure. By increasing the size of the ASR contention window, it becomes disadvantageous in ASR backoff contention, and thus the probability of terminating data transmission of other APs and other STAs when transmitting an ASR data frame may be increased.

After increasing the size of the ASR contention window, the srDATA frame may be retransmitted. If the STA continues to fail the retransmission of the srDATA frame more than a certain number of times, the STA receiving the srDATA frame may be deleted from the ASR list. For example, as described above, when the STA (H), STA (J), and STA (F) receive the dRTS frame and the dCTS frame and do not transmit the srACK frame for the srDATA frame, STA (H), STA(J) and STA(F) may be deleted from the ASR list.

10 is a block diagram showing a wireless device to which an embodiment of the present invention can be applied.

Referring to FIG. 10, the wireless device 1000 is an STA capable of implementing the above-described embodiment, and may be an AP or a non-AP STA (non-AP station).

The wireless device 1000 includes a processor 1020, a memory 1040, and a radio frequency unit 1060.

The RF unit 1060 may transmit/receive radio signals by connecting to the processor 1020.

The processor 1020 implements the functions, processes and/or methods proposed in the present invention. For example, the processor 1020 may be implemented to perform the operation of the wireless device according to the embodiment of the present invention described above.

For example, when the wireless device is an AP, it may be implemented to transmit a dRTS frame or a dCTS frame by an ASR backoff procedure and manage the ASR list.

In addition, when the wireless device is an STA, the processor 1020 may be implemented to transmit a dRTS frame or a dCTS frame and manage the ASR list according to the ASR backoff procedure.

The processor 1020 may include an application-specific integrated circuit (ASIC), another chipset, a logic circuit, a data processing device, and/or a converter for converting a baseband signal and a radio signal to each other. The memory 1040 may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium, and/or other storage device. The RF unit 1060 may include one or more antennas for transmitting and/or receiving radio signals.

When the embodiment is implemented as software, the above-described technique may be implemented as a module (process, function, etc.) that performs the above-described functions. The module is stored in the memory 1040 and may be executed by the processor 1020. The memory 1040 may be inside or outside the processor 1020, and may be connected to the processor 1020 by various well-known means.

Although described with reference to the above embodiments, those skilled in the art will understand that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention described in the following claims. I will be able to.

Claims (12)

In the wireless data transmission method of the first wireless device,
Data frame between the second and third wireless devices over a specific channel
Transmitting a first disruptive request to send (dRTS) frame through the specific channel for determining whether data communication between the second wireless device and the third wireless device is interrupted during the transmission;
If it is determined that collision does not occur in the data frame after the first dRTS frame is transmitted, generating an ASR (aggressive spatial reuse) list including information on a fourth wireless device;
Performing channel access to the specific channel based on an ASR backoff procedure when the specific channel is in use;
Transmitting a spatial reuse DATA (srDATA) frame to the fourth wireless device through the specific channel based on the ASR list; And
The fourth wireless device does not receive the second dRTS frame transmitted through the specific channel in order to determine whether the fifth wireless device and the sixth wireless device to communicate based on the ASR interfere with data communication between other wireless devices. If not, including the step of receiving an srACK (acknowledgement) frame for the srDATA frame from the fourth wireless device,
And when the fourth wireless device receives the second dRTS frame, the fourth wireless device does not transmit the srACK frame to the first wireless device. The method of claim 1,
Performing the channel access comprises:
Selecting a random number in the ASR contention window to determine an ASR backoff time;
Measuring noise power as the ASR backoff time decreases; And
And performing the channel access when the noise power does not exceed a threshold value until the ASR backoff time becomes zero. The method of claim 1,
The first transmission end time at which the transmission of the srDATA frame ends and the second transmission end time at which the transmission of the data frame ends are set to be the same,
Wherein the srDATA frame includes zero padded data when the second transmission end time is longer than the first transmission end time. The method of claim 3,
The information on the second transmission end time is obtained based on a duration field included in a request to send (RTS) frame transmitted by the second wireless device. The method of claim 1,
When the first wireless device does not receive a response frame from the specific wireless device after repeatedly transmitting a frame for a set number of times to a specific wireless device, the ASR list including information on the specific wireless device is Wireless data transmission method, characterized in that updated by deleting information on the wireless device. The method of claim 1,
The step of generating the ASR list
Determining whether a collision has occurred in a data frame transmitted from another wireless device due to the first dRTS frame; And
And if the collision does not occur in the data frame, including the other wireless device in the ASR list. In the first wireless device for transmitting wireless data, the first wireless device,
A radio frequency (RF) unit for transmitting and receiving radio signals; And
Including a processor selectively connected to the RF unit and operating,
The processor is
A first disruptive request to send (dRTS) for determining whether data communication between the second wireless device and the third wireless device is interrupted while a data frame is transmitted between the second wireless device and the third wireless device through a specific channel ) Transmit a frame through the specific channel,
If it is determined that collision does not occur in the data frame after the first dRTS frame is transmitted, an aggregated spatial reuse (ASR) list including information on a fourth wireless device is generated, and
Performing channel access to the specific channel based on the ASR backoff procedure,
Transmitting an srDATA (spatial reuse DATA) frame to the fourth wireless device through the specific channel based on the ASR list,
The fourth wireless device does not receive the second dRTS frame transmitted through the specific channel to determine whether the fifth wireless device and the sixth wireless device to communicate based on ASR interfere with data communication between other wireless devices. If not, implemented to receive an srACK (acknowledgement) frame for the srDATA frame from the fourth wireless device,
The first wireless device, wherein the fourth wireless device does not transmit the srACK frame to the first wireless device upon receiving the second dRTS frame. The method of claim 7,
The ASR backoff procedure is performed while the channel is congested,
ASR backoff time is determined by selecting a random number within the ASR contention window,
As the ASR backoff time decreases, noise power is measured,
The first wireless device, wherein the channel access is performed when the noise power does not exceed a threshold value until the ASR backoff time becomes zero. The method of claim 7,
The first transmission end time at which the transmission of the srDATA frame ends and the second transmission end time at which the transmission of the data frame ends are set to be the same,
The first wireless device, wherein the srDATA frame includes zero padded data when the second transmission end time is longer than the first transmission end time. The method of claim 9,
The information on the second transmission end time is obtained based on a duration field included in a request to send (RTS) frame transmitted by the second wireless device. The method of claim 7,
When the first wireless device does not receive a response frame from the specific wireless device after repeatedly transmitting a frame for a set number of times to a specific wireless device, the ASR list including information on the specific wireless device is The first wireless device, characterized in that updated by deleting information on the wireless device. The method of claim 7,
The processor is implemented to determine whether a collision has occurred in a data frame transmitted from another wireless device due to the first dRTS frame, and to include the other wireless device in the ASR list when there is no collision in the data frame. The first wireless device, characterized in that.

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