KR20150139392A - Method and apparatus for transmitting and receiving data based on aggressive spatial reuse - Google Patents

Abstract

A method and an apparatus for transmitting and receiving data based on aggressive spatial reuse (ASR) are disclosed. The method for wirelessly transmitting data through a first mobile terminal comprises the steps of: transmitting a disruptive request to send (dRTS) frame to generate an ASR list; performing a channel access to a particular channel, based on an ASR backoff procedure; transmitting the srDATA frame from the particular channel to a second mobile terminal, based on the ASR list; and receiving the srACK(acknowledgement) frame in response to the srDATA frame from the second mobile terminal. The particular channel is a channel which a third mobile terminal transmits and receives a data frame; the srDATA frame and the data frame are transmitted from the particular channel at a predetermined time; and the ASR list may be information on a mobile terminal which does not conflict with the data frame, when the first mobile terminal transmits the srDATA frame and receives the srACK frame.

Description

TECHNICAL FIELD [0001] The present invention relates to an ASR-based wireless data transmission method and apparatus,

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

Compared to the early days when the notebook was plugged into a wireless LAN card at the end of the 1990s, now wireless LANs are being installed in a variety of smart devices such as smart phones and smart pads, including notebooks and PCs. In addition to being used in various devices, it has various uses, so Internet access through wireless LAN is basic, various services based on wireless LAN such as file and data transmission between devices and high-quality video streaming are utilized in real life. In recent years, the use of wireless LAN has been expanding to applications that could not have been imagined, such as protecting the safety of the home based on the wireless LAN and contributing to lowering the electricity rate of the customer by operating the home appliances not only in the house but also outside.

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

IEEE 802.11af is a database-based technology in which wireless LANs share TV idle bandwidth. It is down-clocked based on the 5GHz IEEE 802.11ac PHY layer (physical layer). IEEE 802.11af is heavily influenced by frequency regulation on TV idle bandwidth, and recently the US FCC has announced a reverse auction on the TV idle band, and the outcome will be decided in 2015 Attention is attracted.

IEEE 802.11ah enables wide area wireless LAN service using radio wave distance increase based on frequency band characteristics below 1GHz. In addition, a number of low-power sensors operating in a power saving mode are supported, and cellular off-loading is also available. Preamble and beacon signals are designed to suit these service applications, and TIM (Traffic Indication MAP) is also designed in a hierarchical structure.

IEEE 802.11ai is MAC technology for shortening wireless LAN connection time. Filtering the probe response in active scanning shortens the connection time in congestion situations, and shortens the connection time 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 aggressive spatial reuse (ASR).

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

According to an aspect of the present invention, there is provided a wireless data transmission method of a first wireless terminal, the method comprising: transmitting a disruptive request to send (dRTS) frame to an aggressive spatial reuse (ASR) Generating a list, performing channel access to a specific channel based on an ASR backoff procedure, transmitting an srDATA frame from the particular channel to a second wireless device based on the ASR list; And receiving an acknowledgment (SRACK) frame from the second wireless device in response to the srDATA frame, wherein the specific channel is a channel through which the third wireless device transmits and receives data frames, Wherein the data frame is transmitted on the specific channel at a specific time and the ASR list is information about 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. Wherein the ASR backoff procedure comprises selecting a random number N (N is a natural number) within the ASR contention window to determine an ASR backoff time, measuring noise power as the ASR backoff time is reduced, And performing the channel access when the noise power does not exceed the threshold value until the off-time becomes zero. The first transmission end time of the srDATA frame and the second transmission end time of the data frame are set to be equal to each other, and when the second transmission end time is longer than the first transmission end time, . ≪ / RTI > The information on the second transmission end time may be acquired based on a duration field included in an RTS (request to send) frame transmitted by the third wireless device. The ASR list may be updated by deleting the specific wireless device if the first wireless device fails to receive a response frame more than a certain number of times from the specific wireless device that transmitted the frame. Wherein the first wireless device transmits a dRTS frame to generate an ASR list includes determining whether a collision has occurred in a data frame transmitted from another wireless device due to the dRTS frame, And if so, including the other wireless device in the ASR list.

According to an aspect of the present invention, there is provided a first wireless device for transmitting wireless data, the first wireless device including a radio frequency (RF) part; And a processor operatively coupled to the RF unit. The processor generates an aggressive spatial reuse (ASR) list by transmitting a disruptive request to send (dRTS) frame, To transmit an srDATA frame from the specific channel to the second wireless device based on the ASR list and to receive an acknowledgment (SRACK) 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, the srDATA frame and the data frame are transmitted on the specific channel at a particular point in time, and the ASR list indicates that the first wireless device is a srDATA frame And upon receipt of an SRACK frame, transmits a data frame to a wireless device that does not collide with the data frame. Can be seen. Wherein the ASR backoff procedure determines an ASR backoff time by selecting a random number N (N is a natural number) in the ASR contention window, measures the noise power as the ASR backoff time is reduced, The channel access can be performed when the noise power does not exceed the threshold value. The first transmission end time of the srDATA frame and the second transmission end time of the data frame are set to be equal to each other, and when the second transmission end time is longer than the first transmission end time, . ≪ / RTI > The information on the second transmission end time may be acquired based on a duration field included in an RTS (request to send) frame transmitted by the third wireless device. The ASR list may be updated by deleting the specific wireless device if the first wireless device fails to receive a response frame more than a certain number of times from the specific wireless device that transmitted the frame. The processor is configured 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 no collision occurs in the data frame .

As described above, by using the ASR-based wireless data transmission method and apparatus according to the embodiment of the present invention, space resources can be more positively reused than existing wireless LANs, and the effect of increasing the data transmission efficiency in the wireless LAN can be obtained.

1 is a conceptual diagram illustrating a channel access method of a STA based on DCF.
2 is a conceptual diagram showing 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 illustrating a method of transmitting wireless data according to an embodiment of the present invention.
5 is a conceptual diagram illustrating 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 illustrating an ASR list generation method according to an embodiment of the present invention.
10 is a block diagram illustrating a wireless device to which an embodiment of the present invention may be applied.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing.

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

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Hereinafter, the same reference numerals will be used for the same constituent elements in the drawings, and redundant explanations for the same constituent elements will be omitted.

In the embodiment of the present invention, the STA includes a medium access control (MAC) protocol conforming to IEEE (Institute of Electrical and Electronics Engineers) 802.11 standard and a physical layer interface And may be used in a broad sense to include both an AP (access point) and a non-AP STA (Non-AP Station).

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

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

In general, in a channel access method based on DCF (Distributed Coordination Function), if the medium is not in use over the DIFS (DCF inter frame space) period (that is, the channel is idle during DIFS) An impending MPDU (MAC protocol data unit) can be transmitted. If the STA determines that the medium is in use by a carrier sensing mechanism, the STA may determine the size of the contention window (CW) by a random backoff algorithm and perform a backoff procedure have. The STA sets the CW to perform the backoff procedure and selects any timeslot within the CW. The selected time slot is called the backoff time. The STA selecting the relatively short backoff time among the backoff times selected by the plurality of STAs can connect to the medium preferentially over the STA selecting the long backoff time. The remaining STAs can stop the remaining backoff time and wait until the transmission of the STA that is transmitting the frame is completed. After the frame transmission of the STA is completed, the remaining STAs can compete with the remaining backoff time to acquire the medium.

That is, when the STA accesses the channel using the DCF, the STA can detect the channel state for a predetermined time. Specifically, the STA attempts to transmit after a random backoff time if the channel idle during DIFS. The DCF-based transmission method can prevent a collision that occurs when a plurality of STAs transmit frames at the same time, thereby avoiding a collision.

The random backoff time is the time the STA waits before the channel waits for a period of time (e.g., DIFS) and then forwards the frame. The STA can determine the CW based on the minimum CW time CWmin and the maximum CW time CWmax. The STA can calculate the backoff time based on the determined CW.

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

Referring to FIG. 2, a backoff slot may occur after the 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 during the backoff slot that the medium is busy, the STA may not reduce the backoff time. The frame transmission of the STA can be performed when the set backoff timer becomes zero.

Also, in the DCF transmission method, an RTS / CTS access mode in which control frames (request to send (RTS) frames and clear to send (CTS) frames) are exchanged and channels are occupied in advance may be used before data frames are transmitted. This method can reduce the waste of the channel by replacing the collision that may occur when the STA transmits the data frame with the collision caused by the relatively short control frame.

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

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

Referring to FIG. 3, the interval between two frames may be referred to as IFS. The STA can use the carrier sensing method to determine whether the channel is used for a predetermined time period of the IFS. The MAC layer using DCF defines various IFSs. The priority of the STA that occupies the wireless medium by the IFS can be determined. The intervals between frames according to IFS type are as follows.

(1) SIFS (short inter frame symbol): Used for RTS / CTS, ACK frame transmission. Highest priority

(2) PIFS (PCF IFS): Used when transmitting PCF frames

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

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

In the case where only a DCF is used as a method for a plurality of STAs to share a wireless medium in the MAC layer, various problems may occur. For example, when a DCF is used, when a plurality of STAs try to perform initial access to the AP at the same time, a lot of collisions occur between a plurality of STAs. Also, because there is no concept of transmission priority in the DCF, quality of service (QoS) for traffic data transmitted from the STA can not be guaranteed. To solve these problems, 802.11e defines a new coordination function, HCF (hybrid coordination function), to improve the channel access performance of existing DCF and HCF. HCF defines two channel access schemes, HCFC controlled channel access (HCCA) and enhanced distributed channel access (EDCA), similar to those defined in existing 802.11 MACs.

In EDCA and HCCA, traffic categories, which are transmission priorities, can be defined and the priority of access to a channel can be determined based on this. That is, the CW and the IFS are defined according to the category of the traffic data transmitted by the STA, so that the channel access priority according to the type of the traffic data can be determined.

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

If EDCA is used, traffic data with higher priority may have a greater chance of being transmitted relative to lower priority traffic data. Also, on average, an STA with high priority traffic can have less latency than an STA with low priority traffic before sending a packet. In EDCA, transmission priority is assigned by assigning a shorter CW to higher priority traffic than lower priority traffic and by allocating an arbitration inter-frame space (AIFS), which is an IFS shorter than IFS, which is the frame interval defined in DCF. . The EDCA also allows the STA to connect to the channel without contention for a period of time called TXOP (Transmit Opportunity). As long as the TXOP period does not exceed the maximum duration, the STA can transmit as many packets as possible. If one frame is too long and can not be transmitted during one TXOP, it can be cut into small frames and transmitted. The use of TXOP can reduce the situation in which the STA having a low data rate, which is a problem of existing 802.11 DCF MAC, occupies an excessive channel.

In the existing IEEE 802.11 based wireless LAN, data collision occurs because a plurality of STAs or APs transmit data to each other competitively. In order to prevent this, the STA which wants to transmit data confirms whether the corresponding channel is used by other STAs and transmits the frame only when it is confirmed that no channel is used, .

However, the distance between the STAs is more than a certain distance, so that even if a frame is transmitted and received between different APs and STAs at the same time, data can be normally received without collision between frames. In a case where a collision between frames does not occur, the overall data transmission efficiency in the wireless LAN can be increased.

In the embodiment of the present invention, it is possible to check whether a collision between frames occurs in a situation where another node (STA or AP) occupies the corresponding channel to transmit the frame, and transmit the frame. That is, even if a frame is spaced apart from a node transmitting and receiving a current frame, it is possible to transmit a frame after confirming a case where another node does not cause a collision with a frame transmitted and received. By using such a frame transmission method, the overall data transmission efficiency in the wireless LAN can be increased.

For example, in order to positively recycle space, an STA may artificially cause a collision when transmitting data, and a case where an artificial collision does not affect data transmission can be utilized positively.

In the embodiment of the present invention, unlike a conventional WLAN, a specific STA and / or another AP adjacent to another AP may transmit and receive data simultaneously on the same channel. Hereinafter, the operation of the AP and the STA will be described separately for the sake of convenience of explanation. However, as described above, the STA includes both an access point (AP) and a non-AP STA Can be used to mean. For example, in the case of wifi-direct, the STAs may all be interpreted as non-AP STAs. That is, hereinafter, the STA to be published in the embodiment of the present invention can be interpreted as an access point (AP) or a non-AP STA (Non-AP Station).

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

4A shows the positions 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, even when transmission and reception of data between different STAs are performed according to the location of a specific STA, it is possible to determine whether a specific STA collides with data and transmit and receive data through the same channel .

Referring to FIG. 4B, the STA C 430 posts a case in which the STA X 400 transmits a dRTS (request to send) frame while transmitting and receiving a data frame with the STA D 440. When the STA X 400 determines that a collision of a data frame occurs during transmission and reception of a data frame between the STA C 430 and the STA D 440, the transmission frame is referred to as a Disruptive RTS (dRTS) frame (or a stabbing RTS frame).

The dRTS frame transmitted by the STA X 400 may collide with the data frame transmitted by the STA C 430. The collision may prevent the STA C 430 from receiving an ACK frame from the STA D 440 in response to the data frame.

If the STA C 430 fails to receive the ACK for the transmitted data frame, the STA C 430 can retransmit the data frame. The MAC header of the retransmitted data frame may be set to a RET field. The STA X 400 can recognize a situation in which the STA D 440 does not send an ACK to the STA C 430 but can not transmit the dRTS frame when the STA C 430 retransmits the data frame . The STA D 440 may transmit an ACK to the STA C 430 with respect to the data frame retransmitted by the STA C 430. STA X 400 can determine that transmission and reception of ASR-based data is impossible based on this procedure.

FIG. 4C shows a case where the dRTS frame transmitted by the STA B 420 does not collide with the data frame transmitted by the STA C 430. In this case, the STA D 440 may transmit an ACK frame in response to the data frame received from the STA C 430. That is, when the STA is away from another STA by a certain distance, the influence of the dRTS frame is insignificant, so that the data frame transmitted by the STA C 430 can be correctly received without being broken. Unlike STA X 400, STA D 440 can transmit an ACK after SIFS to STA C 430. If the STA B 420 receives the ACK transmitted by the STA D 440 or if it is confirmed that the STA C 430 does not retransmit the data frame, the STA B 420 determines that the STA C 430 is in an area capable of transmitting and receiving data based on ASR . Hereinafter, it is assumed that an ACK frame other than a NACK frame is received in response to a data frame for convenience of description.

Thus, the STA or the AP that desires to perform the ASR can determine whether or not the ASR can be performed through the relationship with the neighboring AP and / or the neighboring STAs. For example, an STA that wishes to perform an ASR can generate an ASR list to which an ASR strategy can be applied based on the relationship with the neighboring APs and / or neighboring STAs. The ASR list may include information related to the STA and / or the APs with which the STA can perform the ASR. A method of generating the ASR list will be described later.

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

In FIG. 5, the STA B 520 and the STA E 550 both use the ASR and start to transmit the srDATA frame. The term srDATA frame may be used to distinguish transmitted and received data frames from existing data frames based on the ASR method.

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

That is, if a collision occurs between the first srDATA frame transmitted from the STA B 520 to the STA A 510 and the second srDATA frame transmitted from the STA E 550 to the STA A 510, the STA A 510 It may not receive the first srDATA frame and the second srDATA frame.

In order to prevent the collision problem between the SRDATA frames, channel resources may be acquired based on a back-off procedure even when frames are transmitted based on the ASR. Even when transmitting a frame based on the ASR, the back-off procedure can be performed differently from the conventional back-off procedure.

The existing random back-off procedure operates when the 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 the channel is in a busy state.

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

And stores information on the current noise power (Pn).

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

If the measured current noise power exceeds a certain threshold value as the ASR backoff time is decreased, another STA is considered to be transmitting an ASR-based frame by winning the ASR-based back-off competition, It may not perform transmission for the frame.

On the contrary, when the ASR backoff time is reduced, the value becomes 0 and the ASR backoff time becomes 0. When the measured current noise power does not exceed the predetermined threshold value, the STA can perform transmission for the ASR frame.

That is, according to an embodiment of the present invention, a frame transmitted by another STA or another AP may be detected in a channel on which the STA operates, and it may be determined 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 ASR frames (e.g., srDATA and dRTS frames).

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

STA B 620 can simultaneously access channels through which STA C 430 and STA D 640 transmit and receive frames through the ASR-based back-off procedure described above. The STA B 620 may perform the ASR and transmit the srDATA frame to the STA A 610 without causing a collision on the data frame transmitted by the STA C 630.

In this case, the STA A 610 responds to the srDATA frame transmitted by the STA B 620 with an SRACK frame, and may collide with a data frame transmitted by another AP and / or STA in the corresponding channel.

For example, STA B 620 may transmit an srDATA frame to STA A 610 while STA C 630 is transmitting a data frame to STA D 640. If the transmission time of the SRDATA frame transmitted by the STA B 620 is relatively faster than the transmission time of the data frame of the STA C 630, In this case, the SRACK transmitted by the STA A 610 to the STA B 620 may collide with the data frame transmitted by the STA C 630. In this case, STA B 620 can not receive the SRACK transmitted from STA A 610. In order to solve this problem, the STA B 420 must be able to transmit the size of the srDATA frame in accordance with the size of the data frame transmitted by the STA C 430.

Therefore, according to the embodiment of the present invention, in order to solve this problem, it is possible to set the time for the STA C 430 to terminate the transmission of the data frame and the time for the STA B 420 to terminate the transmission of the srDATA frame .

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

7 shows a method of setting the time at which the STA and / or the AP transmitting the srDATA frame ends the transmission of the srDATA frame and the time at which the other STA and / or the other AP transmitting the data frame terminate the transmission of the data frame Lt; / RTI &gt;

7, the STA B 720 performing the ASR checks whether the second end time of the transmission of the srDATA frame is the same as the second end time of the transmission of the data frame transmitted by the STA C 730 Can be set.

The STA B 720 can set the same size of the data frame transmitted by the STA B 720 and the srDATA frame transmitted by the STA B 720 to set the second end time to be equal to the first end time . For example, in consideration of the modulation and channel coding method, the STA B 720 may transmit the ASR data frame to the STA B 720 so that the transmission end time of the data frame is equal to the end time of transmission of the ASR data frame. The time to transmit can be determined. By using this method, the STA A 710 can prevent a collision with a frame transmitted by another AP and / or another STA when transmitting a srACK frame for an srDATA frame.

The STA B 720 transmits a data frame transmitted by the STA C 730 before the data frame transmission of the STA C 730 in order to ensure that the transmission time of the STA C 730 is the same as the time at which transmission of the data frame ends, Information on the transmission end time of the data frame of the STA C 730 can be obtained based on the Duration field of the RTS frame to be transmitted before transmission. The STA B 720 may set the transmission end time of the srDATA frame to be the same based on the information on the transmission end time of the data frame of the STA C 730. For example, the srDATA frame may perform zero padding to set the transmission end time to be the same. 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). The MPDU is aggregated to transmit the data frame, and the null padding can transmit only the sub-frame header of the A-MPDU.

By using this method, the SRACK frame transmitted from the STA A 710 may not collide with the data frame transmitted by the STA C 730 in a temporal manner. If the SRACK frame collides with the data frame transmitted by the STA C 730 in time, interference may occur between them, and an error may occur in data reception. Thus, using this method, STA B 720 can receive the srACK frame from STA A 710 without interference of data frames.

However, even if the STA A 710 transmits an SRACK frame based on such a method, the STA 710 may transmit the SRACK frame to another STA or another AP (for example, the STA D 740) The srACK frame 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 the second STA transmits an SRACK frame based on the method described in FIG. 7, a solution to the case where an ACK frame transmitted by the second STA conflicts with an ACK frame transmitted by another STA or another AP . If the ACK frame transmitted by the second STA conflicts with the ACK frame transmitted by another STA or another AP, the ASR procedure can be stopped according to a certain determination.

8, STA (E), STA (G), and STA (J), which are a plurality of STAs, communicate with STA (F), STA (H), and STA (I), respectively. The STA A to STA I posted in FIG. 8 can be assumed to be the STA located at the posted position in FIG.

STA C 800 can transmit and receive frames with STA D 850. [ In this situation, at least one STA of the STA (E), the STA (G) and the STA (J) performs an ASR-based random backoff procedure to transmit the srDATA frame to the STA (F), the STA (H) To at least one STA among the plurality of STAs. As described above, the srDATA frame may perform zero padding to set the time at which transmission of the data frame transmitted by the STA C 800 ends and the time at which transmission of the srDATA frame ends.

When transmitting an srDATA frame, at least one STA of STA (F), STA (H) and STA (I) can transmit a srACK frame in response thereto. The SRACK frame may cause a collision with the ACK frame transmitted by the STA D 810.

To prevent this 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 illustrating an ASR list generation method according to an embodiment of the present invention.

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

In the following description, it is assumed that the AP transmits a dRTS frame for convenience of description, but the STA may transmit the dRTS frame. In FIG. 9, the node H, the node J, the node F, the node E, the node G, and the node I are assumed to be STAs for convenience of explanation, but the specific STAs may be interpreted as APs as described above.

First, the STA C 900 which desires to perform the ASR can transmit the dRTS frame. the STA D 950 may transmit the dCTS frame in response to the dRTS frame.

In this case, other STAs and / or other APs located in the vicinity of STA C 900 and STA D 950 may receive dRTS frames and / or dCTS frames. For example, STA (H), STA (J), and STA (F) adjacent to STA C 900 and STA D 950 can receive a dRTS frame and a dCTS frame. In this case, even when an STA (H), STA (J), and STA (F) receive an srDATA frame from one STA of STA (E), STA I can not. That is, when the STA C 900 and the STA D 950 perform the ASR, the AP or the STA receiving the dRTS frame and the dCTS frame, which are located within the transmission coverage of the STA C 900 and the STA D 950, Based data transmission and reception procedures.

Also, an AP or a STA that is not located within the transmission coverage of the STA C 900 and the STA D 950 and has not received the dRTS frame or the dCTS frame determines whether or not the reception of the srACK response frame for its own srDATA frame has been received, Based data transmission and reception procedures.

For example, one STA of STA (E), STA (G) and STA (I) can transmit an srDATA frame to STA (H), STA (J), STA (F). it is possible to determine whether or not the srACK frame is received in response to the srDATA frame after a predetermined 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 the SRACK frame is not received in response to the srDATA frame after a predetermined time (SIFS) after transmitting the ASR data frame, the SRACK frame may not be received. This is because STA (H), STA (J) and STA (F) have not already responded to the srDATA frames of STA (E), STA (G) and STA (I) as described above. 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 is disadvantageous in the competition of the ASR backoff, so that it is possible to increase the probability that the data transmission of another AP or another STA is terminated when the ASR data frame is transmitted.

After increasing the size of the ASR contention window, the srDATA frame can be retransmitted. If the STA continues to retransmit the srDATA frame for more than a predetermined number of times, the STA receiving the srDATA frame may be deleted from the ASR list. For example, if STA (H), STA (J), and STA (F) receive a dRTS frame and a dCTS frame and do not transmit a srACK frame for an srDATA frame, STA (H) STA (J), STA (F) can be deleted from the ASR list.

10 is a block diagram illustrating a wireless device to which an embodiment of the present invention may 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.

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

The RF unit 1060 may communicate with the processor 1020 to transmit / receive a radio signal.

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

For example, if 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.

Also, if the wireless device is a STA, the processor 1020 may similarly be implemented to transmit a dRTS frame or a dCTS frame by an ASR backoff procedure and manage the ASR list.

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 baseband signals and radio signals. Memory 1040 may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and / or other storage devices. RF section 1060 may include one or more antennas for transmitting and / or receiving wireless signals.

When the embodiment is implemented in software, the above-described techniques may be implemented with modules (processes, functions, and so on) that perform the functions described above. The module may be stored in memory 1040 and executed by processor 1020. [ The memory 1040 may be internal or external to the processor 1020 and may be coupled to the processor 1020 in a variety of well known means.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims. It will be possible.

Claims (12)

A wireless data transmission method of a first wireless device,
generating an ASR (aggressive spatial reuse) list by transmitting a disruptive request to send (dRTS) frame;
Performing channel access to a specific channel based on an ASR backoff procedure;
Transmitting an srDATA frame from the particular channel to a second wireless device based on the ASR list; And
Receiving an acknowledgment (SRACK) frame in response to the srDATA frame from the second wireless device,
The particular channel is the channel through which the third wireless device transmits and receives data frames,
Wherein the srDATA frame and the data frame are transmitted on the specific channel at a particular point in time,
Wherein the ASR list is 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. The method according to claim 1,
The ASR backoff procedure operates in a congested channel state,
Selecting a random number N (N is a natural number) within the ASR contention window to determine an ASR backoff time;
Measuring noise power as the ASR backoff time is reduced; And
And performing the channel access if the noise power does not exceed the threshold value until the ASR backoff time becomes zero. The method according to claim 1,
The first transmission end time of the srDATA frame and the second transmission end time of the data frame 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,
Wherein 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 third wireless device. The method according to claim 1,
Wherein the ASR list is updated by deleting the specific wireless device if the first wireless device fails to receive a response frame more than a certain number of times from the specific wireless device that transmitted the frame. 2. The method of claim 1, wherein the first wireless device transmits a dRTS frame to generate an ASR list,
Determining whether a collision has occurred in a data frame transmitted from another wireless device due to the dRTS frame; And
And if the collision does not occur in the data frame, including the other wireless device in the ASR list. A first wireless device for transmitting wireless data, the first wireless device comprising:
A radio frequency (RF) unit for transmitting and receiving a radio signal; And
And a processor operatively coupled to the RF unit,
The processor generates an aggressive spatial reuse (ASR) list by transmitting a disruptive request to send (dRTS) frame,
Performs channel access to a specific channel based on an ASR backoff procedure,
Transmitting an srDATA frame from the particular channel to a second wireless device based on the ASR list,
An acknowledgment (SRACK) frame in response to the srDATA frame from the second wireless device,
The particular channel is the channel through which the third wireless device transmits and receives data frames,
Wherein the srDATA frame and the data frame are transmitted on the specific channel at a particular point in time,
Wherein the ASR list is 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. 8. The method of claim 7,
The ASR backoff procedure operates in a congested channel state,
The ASR backoff time is determined by selecting a random number N (N is a natural number) in the ASR contention window,
Measuring the noise power as the ASR backoff time is decreased,
And performs the channel access if the noise power does not exceed a threshold value until the ASR backoff time becomes zero. 8. The method of claim 7,
The first transmission end time of the srDATA frame and the second transmission end time of the data frame 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. 10. The method of claim 9,
Wherein the information on the second transmission end time is acquired based on a duration field included in an RTS (request to send) frame transmitted by the third wireless device. 8. The method of claim 7,
Wherein the ASR list is updated by deleting the specific wireless device when the first wireless device fails to receive a response frame more than a predetermined number of times from the specific wireless device transmitting the frame. 8. The apparatus of claim 7,
Determines whether a collision has occurred in a data frame transmitted from another wireless device due to the dRTS frame,
And if the collision does not occur in the data frame, the other wireless device is included in the ASR list.

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