KR102150037B1 - Frame transmitting method for uplink mu-mimo communication - Google Patents

Abstract

A frame transmission/reception method for multi-user-multi-input multi-out (MU-MIMO) communication in an access point (AP) is disclosed. The frame transmission/reception method according to an embodiment includes the steps of determining at least one transmitting station, transmitting an uplink multi-user poll (UL MU Poll) frame requesting a data frame to the at least one transmitting station, the at least It may include simultaneously receiving a data frame from one transmitting station and transmitting an Ack frame corresponding to the data frame reception to the at least one transmitting station.

Description

Frame transmission method for Ｕｐｌｉｎｋ ＭＵ-ＭＩＭＯ communication {FRAME TRANSMITTING METHOD FOR UPLINK MU-MIMO COMMUNICATION}

The present disclosure relates to a protocol of a wireless LAN, and in particular, to a method of transmitting a frame using an Uplink MU-MIMO technology.

In recent wireless communication systems, MIMO technology for transmitting and receiving data using two or more antennas has become common. The IEEE 802.11n standard allows the use of two or more transmit antennas in the wireless LAN, but up to four antennas can be used in 802.11n and eight antennas in 802.11ac. In addition, when multiple transmit antennas are used, data may be transmitted using a transmit beamforming technique in order to improve signal reception performance.

In IEEE 802.11ac, which is currently undergoing standardization, in order to use frequency resources more efficiently, an access point (AP) simultaneously transmits a beamformed data frame to several STAs. In addition, studies on Uplink MU-MIMO technology in which several STAs simultaneously transmit data frames to the AP, and the AP separately receive data frames transmitted by several STAs simultaneously for each stream are being conducted. .

An example of an operation when two or more stations want to transmit data to an AP using a conventional WLAN technology is shown in FIG. 1A. Station 1 (STA 1) and station 1 (STA 2) start a random backoff when the channel becomes idle, and in FIG. 1A, station 1 (STA 1), which has been backed off first, sends the first data to the AP. The frame (Data frame 1) is transmitted, and the first ACK (Ack 1) is received. At this time, since station 1 (STA 2) can listen to the frames transmitted by station 1 (STA 1), the backoff is stopped, and after the first ACK frame is over, the station 1 (STA 2) backs off again to the AP. Transmit a data frame (Data frame 2).

Here, an example of operation when the Uplink MU-MIMO technology is applied is shown in FIG. 1B.

As in FIG. 1A, when the channel becomes idle, the station 1 (STA 1) and the station 1 (STA 2) start random backoff, and the station 1 (STA 1), which has finished backoff first, starts beamforming first data. The frame (Data frame 1) is transmitted to the AP. However, since this frame is beamformed, the station 1 (STA 2) cannot hear this frame, so after continuing backoff, the beamformed second data frame (Data frame 2) is transmitted to the AP.

However, from the point of view of the AP, if the second data frame 2 is received while the first data frame 1 is being received, the PHY layer cannot properly receive data. According to the published research results, Uplink MU-MIMO frames can be received only when they are temporally synchronized within an error of 100 ns or less.

Therefore, it is impossible to receive Uplink MU-MIMO data using the conventional method.

According to an embodiment, a frame transmission/reception method for multi-user-multi-input multi-out (MU-MIMO) communication in an access point (AP) includes: determining at least one transmitting station, and transmitting data to the at least one transmitting station. Transmitting an uplink multi-user poll (UL MU Poll) frame requesting a frame, simultaneously receiving a data frame from the at least one transmitting station, and an ac corresponding to receiving a data frame to the at least one transmitting station ( Ack) may include the step of transmitting the frame.

The uplink multi-user poll frame may include identification information of each of the at least one transmission station.

The identification information of each of the at least one transmitting station may include at least one of a MAC address, an AID, and partial AID information in IEEE 802.11ac.

The uplink multi-user poll frame may include at least one of the number of transmission stations and transmission period information.

The step of transmitting an uplink multi-user poll (UL MU Poll) frame may be performed based on a multi-user multi-input multi-out (MU MIMO) technique or may be transmitted in a non-beamformed state.

The receiving of the data frame may include receiving the data frame based on a multi-user multi-input multi-out (MU MIMO) technique.

The transmitting of the ACK frame may include transmitting a Group Ack frame including at least one of identification information of the at least one transmitting station and a bitmap in which each of the at least one transmitting station is mapped to one bit. I can.

In the transmitting of the ACK frame, the group ACK may be transmitted without beamforming.

In the transmitting of the ACK frame, each of the at least one ACK frame including identification information of each of the at least one transmission station may be transmitted.

In the transmitting of the ACK frame, the at least one ACK frame may be transmitted based on a multi-user multi-input multi-out (MU MIMO) technique.

On the other hand, the frame transmission/reception method for multi-user-multi-input multi-out (MU-MIMO) communication in a transmitting station according to another embodiment is an uplink multi-user poll (UL) requesting a data frame from an access point (AP). MU Poll) receiving a frame, receiving the UL MU Poll frame and transmitting a data frame to the access point after a predetermined time (SIFS), and corresponding to the reception of the data frame It may include the step of receiving an Ack frame.

The uplink multi-user poll frame may include identification information of each of the at least one transmission station.

The identification information of each of the at least one transmitting station may include at least one of a MAC address, an AID, and partial AID information in IEEE 802.11ac.

The uplink multi-user poll frame may include at least one of the number of transmission stations and transmission period information.

The step of receiving an uplink multi-user poll (UL MU Poll) frame may be received based on a multi-user multi-input multi-out (MU MIMO) technique or may be received in a non-beamformed state.

In the transmitting of the data frame, the data frame may be transmitted based on a multi-user multi-input multi-out (MU MIMO) technique.

In the receiving of the ACK frame, a Group Ack frame including at least one of identification information of the transmitting station and a bitmap in which each of the transmitting stations is mapped to one bit may be received.

The receiving of the ACK frame may include receiving the group ACK without beamforming.

In the receiving of the ACK frame, an ACK frame including identification information of the transmitting station may be received.

The receiving of the ACK frame may include receiving the ACK frame based on a multi-user multi-input multi-out (MU MIMO) technique.

An access point for multi-user-multi-input multi-out (MU-MIMO) communication according to another embodiment includes a control unit for determining at least one transmitting station and an uplink multi-user requesting a data frame from the at least one transmitting station And a communication unit that transmits a UL MU Poll frame, simultaneously receives data frames from the at least one transmitting station, and transmits an Ack frame corresponding to data frame reception to the at least one transmitting station. I can.

A transmitting station for multi-user-multi-input multi-out (MU-MIMO) communication according to another embodiment receives an uplink multi-user poll (UL MU Poll) frame requesting a data frame from an access point (AP). And a control unit for controlling the communication unit to receive the UL MU Poll frame and transmit a data frame to the access point after a preset time (SIFS), and the communication unit An Ack frame corresponding to data frame reception may be received.

The communication unit transmits the data frame based on a multi-user multi-input multi-out (MU MIMO) technology, receives a group ACK without beamforming, and multiplies an ACK frame including identification information of the transmitting station. It can be received based on user multi-input multi-out (MU MIMO) technology.

1A and 1B are conceptual diagrams illustrating an operation when two or more stations in the related art attempt to transmit data to an AP.
2 is a block diagram of an AP and a station according to an embodiment.
3 is a timing diagram illustrating operations of an AP and a station according to an embodiment.
4 is a structure of a UL MU Poll frame according to an embodiment.
5 and 6 are structures of group ACKs according to various embodiments.
7 and 8 are conceptual diagrams of a UL MU-MIMO data transmission protocol according to various embodiments.

Hereinafter, some embodiments will be described in detail with reference to the accompanying drawings. However, it is not limited or limited by these embodiments. The same reference numerals in each drawing indicate the same members.

The terms used in the description below have been selected as currently widely used general terms as possible while taking functions of the present invention into consideration, but this may vary according to the intention or custom of a technician working in the art, the emergence of new technologies, and the like.

In addition, in certain cases, there are terms arbitrarily selected by the applicant for better understanding and/or convenience of description, and in this case, detailed meanings will be described in the corresponding description. Therefore, terms used in the following description should be understood based on the meaning of the term and the contents throughout the specification, not just the name of the term.

2 is a block diagram of an AP and a station according to an embodiment.

As shown in FIG. 2, the AP 100 may include a control unit 110 and a communication unit 120.

The control unit 110 may generate a frame transmitted from the communication unit 120. The control unit 110 may process the frame received from the communication unit 120. The controller 110 may control the communication unit 120 to perform communication with at least one of the communication units 220-1, 220-2, and 220-n of the station based on the MIMO method.

Meanwhile, the controllers 210-1, 210-2, and 210-n may process frames received from the communication units 220-1, 220-2, and 220-n or generate frames transmitted by the communication units 220-1, 220-2, and 220-n. . The controllers 210-1, 210-2, 210-n may control the communication units 220-1, 220-2, 220-n so that, for example, a UL MU poll frame is received and a data frame is transmitted after SIFS.

The controller 110 or 210-1,210-2,210-n may be implemented with an IC chip, a microprocessor, a mini computer, or the like, and, for example, the communication unit 120 may determine a station for performing communication. The operation of the control unit 110 or 210-1,210-2,210-n will be described in more detail later.

The communication unit 120 of the AP 100 may communicate with at least one of the communication units 220-1, 220-2, and 220-n of the station 200. The communication unit 120 of the AP 100 includes at least one of the communication units 220-1, 220-2, 220-n of the station 200 and an uplink multi-user poll frame (hereinafter, referred to as UL MU Poll frame). , It is possible to transmit and receive a data frame and an Ack frame. The communication unit 120 may include various communication modules such as an antenna, a demodulator/modulator, a frequency processing device, and a filter device.

3 is a timing diagram illustrating operations of an AP and a station according to an embodiment.

In step 310, the AP 100 may determine a transmitting station to transmit the data frame. For example, the AP 100 may determine at least one of a plurality of stations in the environment shown in FIG. 2 as the transmitting station.

In step 320, the AP 100 may transmit a UL MU Poll frame to the station 200. The UL MU Poll frame may be a frame indicating a transmission station, and may also be a frame indicating a transmission station to transmit a data frame. After receiving the UL MU Poll frame, the transmitting station may be preset to transmit the data frame after a preset time (SIFS). Meanwhile, in another embodiment, the AP 100 may use the RTS/CTS exchange prior to transmission of the UL MU Poll frame for protection.

The structure of the UL MU Poll frame according to an embodiment may be the same as that of FIG. 4. As shown in FIG. 4, the UL MU Poll frame includes a frame control field (Frame Control), an RA field (RA), a TA field (TA), a UL MU-MIMO common information field (UL MU-MIMO Info), and a transmission station. Fields STA1, STA2, and STAn may include an FCS field (FCS). As described above, the UL MU Poll frame may include the transmission station fields STA1, STA2, and STAn, and may include identification information on the transmission station. In an embodiment, the identification information for the transmitting station may include at least one of information such as a MAC address, an AID, and a Partial AID such as in IEEE 802.11ac.

Meanwhile, the UL MU Poll frame may include UL MU-MIMO common information. The UL MU-MIMO common information may include the number of stations that will simultaneously transmit a data frame and an L-LENTGH value included in the L-SIG among the PHY layer overhead. Here, simultaneous may mean the same thing in time or within a preset error range. The transmission period information field (L-LENGTH) may be used as a LENGTH value included in the L-SIG of a beamformed data frame to be transmitted by stations during an uplink MU-MIMO transmission period.

If the PPDU type of the beamformed data frame is HT or VHT PPDU, the LENGTH field of L-SIG is converted to the temporal length of the frame. Accordingly, when the stations transmit a data frame, they can transmit an amount of data corresponding to the temporal length specified in L-LENGTH.

Again, referring to FIG. 3, the station 200 may receive a UL MU Poll frame. The station 200 may determine whether the station itself is a transmitting station by checking identification information on the transmitting station in the UL MU Poll frame.

In step 330, if the station 200 is a transmitting station, it may receive a UL MU Poll frame and transmit a data frame after SIFS. In addition, as other transmitting stations also receive the UL MU Poll frame and transmit the data frame after SIFS, all transmitting stations can simultaneously transmit the data frame to the AP.

In step 340, the AP 100 may transmit an Ack frame to the transmitting station 200. The AP 100 must transmit an Ack frame to all transmitting stations, and for this purpose, a group address indicating a preset UL MU-MIMO group may be used as an RA. An Ack frame including a group address may be referred to as a group Ack.

5 and 6 are structures of group ACKs according to various embodiments. As shown in FIG. 5, it can be seen that the group address (UL MU Group) is included in the RA field. In an embodiment, the group address may include identification information of a transmitting station that has successfully received a data frame, to indicate whether to receive a data frame.

In addition, as shown in FIG. 6, a UL MU Ack bitmap may be further included. Here, the UL MU ACK bitmap may be a bitmap in which one bit is mapped to one STA. The UL MU ACK bitmap may be created based on a list of stations included in the UL MU Poll frame and their order.

At least one of the UL MU Poll frame and the Ack frame according to an embodiment may be transmitted based on a downlink MU-MIMO (down link MU-MIMO) method or may be transmitted without performing beamforming.

7 and 8 are conceptual diagrams of a UL MU-MIMO data transmission protocol according to various embodiments. In more detail, FIG. 7 illustrates a data transmission protocol for a case where UL MU Poll and Group Ack do not use MU-MIMO technology.

Referring to FIG. 7, the AP may use an RTS/CTS exchange prior to transmission of a UL MU Poll frame for protection. In more detail, the AP may perform backoff after a channel busy period. When backoff is performed, the AP may transmit an RTS to the stations STA1 and STA2. When the stations STA1 and STA2 receive the RTS, they may transmit the CTS to the AP after SIFS.

When the AP receives the CTS, it may transmit the UL MU Poll frame to the transmitting stations STA1 and STA2 after SIFS. Transmission of the UL MU Poll frame may be performed without beamforming.

The transmitting stations STA1 and STA2 may transmit data frames (Data frame1, Data frame2) after SIFS from reception of the UL MU Poll frame. Here, the data frames (Data frame 1, Data frame 2) may be transmitted based on the MU-MIMO technology.

The AP may receive data frames (Data frame 1, Data frame 2) and transmit a group acknowledgment frame to the transmitting stations after SIFS. Here, the group acknowledgment frame may be performed without beamforming.

Meanwhile, FIG. 8 is for a case of transmitting UL MU Poll and Ack using Downlink MU-MIMO technology.

Referring to FIG. 8, the AP may use RTS/CTS exchange prior to transmission of the UL MU Poll frame for protection. In more detail, the AP may perform backoff after a channel busy period. When backoff is performed, the AP may transmit an RTS to the stations STA1 and STA2. When the stations STA1 and STA2 receive the RTS, they may transmit the CTS to the AP after SIFS.

When the AP receives the CTS, it may transmit the UL MU Poll frame to the transmitting stations STA1 and STA2 after SIFS. The UL MU Poll frame may be transmitted based on MU-MIMO technology.

The transmitting stations STA1 and STA2 may transmit data frames (Data frame1, Data frame2) after SIFS from reception of the UL MU Poll frame. Here, the data frames (Data frame 1, Data frame 2) may be transmitted based on the MU-MIMO technology.

The AP may receive data frames (Data frame1, Data frame2) and transmit each of the first acknowledgment frame and the second frame to the transmitting stations after SIFS. Here, the first and second ACK frames may be transmitted based on MU-MIMO technology. In this case, each of the first acknowledgment frame and the second frame may include first station identification information and second station identification information.

The apparatus described above may be implemented as a hardware component, a software component, and/or a combination of a hardware component and a software component. For example, the devices and components described in the embodiments include, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable array (FPA), It can be implemented using one or more general purpose computers or special purpose computers, such as a programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications executed on the operating system. In addition, the processing device may access, store, manipulate, process, and generate data in response to the execution of software. For the convenience of understanding, although it is sometimes described that one processing device is used, one of ordinary skill in the art, the processing device is a plurality of processing elements and/or a plurality of types of processing elements. It can be seen that it may include. For example, the processing device may include a plurality of processors or one processor and one controller. In addition, other processing configurations are possible, such as a parallel processor.

The software may include a computer program, code, instructions, or a combination of one or more of these, configuring the processing unit to behave as desired or processed independently or collectively. You can command the device. Software and/or data may be interpreted by a processing device or to provide instructions or data to a processing device, of any type of machine, component, physical device, virtual equipment, computer storage medium or device. , Or may be permanently or temporarily embodyed in a transmitted signal wave. The software may be distributed over networked computer systems and stored or executed in a distributed manner. Software and data may be stored on one or more computer-readable recording media.

The method according to the embodiment may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like alone or in combination. The program instructions recorded on the medium may be specially designed and configured for the embodiment, or may be known and usable to those skilled in computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as CD-ROMs and DVDs, and magnetic media such as floptical disks. -A hardware device specially configured to store and execute program instructions such as magneto-optical media, and ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine language codes such as those produced by a compiler but also high-level language codes that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operation of the embodiment, and vice versa.

As described above, although the embodiments have been described by the limited embodiments and drawings, various modifications and variations are possible from the above description by those of ordinary skill in the art. For example, the described techniques are performed in a different order from the described method, and/or components such as a system, structure, device, circuit, etc. described are combined or combined in a form different from the described method, or other components Alternatively, even if substituted or substituted by an equivalent, an appropriate result can be achieved.

Therefore, other implementations, other embodiments, and claims and equivalents fall within the scope of the claims to be described later.

Claims (20)

In a method for transmitting and receiving a frame for a multi-user (MU) communication by an access point (AP),
Determining at least one transmitting station (Station, STA);
Transmitting an uplink multi-user poll (UL MU poll) frame requesting transmission of an uplink multi-user (UL MU) to the at least one transmitting STA;
Receiving a frame from the at least one transmitting STA in response to the transmitted UL MU poll frame; And
Transmitting an acknowledgment (ACK) frame to the at least one transmitting STA in response to the frame; Including,
The UL MU poll frame includes a common information field including a LENGTH field,
The LENGTH field represents the LENGTH field of the L-SIG of the frame received by the AP,
In the step of transmitting the ACK frame, the AP transmits at least one ACK frame, wherein each of the at least one ACK frame includes identification information of each of at least one transmitting STA transmitting the frame to the AP, How to send and receive frames.
The method of claim 1,
The UL MU poll frame further includes identification information of each of at least one transmitting STA that transmits the frame to the AP.
The method of claim 2,
The identification information of each of the at least one transmitting STA includes at least one of a MAC address, an Association ID (AID), and partial AID information in IEEE 802.11ac.
The method of claim 1,
The UL MU poll frame further includes information on the number of transmitting STAs that transmit the frame to the AP.
The method of claim 1,
Transmitting the UL MU poll frame; is performed on the basis of the MU communication, frame transmission and reception method.
The method of claim 1,
Transmitting the UL MU Poll frame; is performed on the basis of a multi-user-multi-input multi-output (Multi User-Multi Input Multi Output, MU-MIMO), frame transmission and reception method.
The method of claim 1,
Receiving the frame; is performed on the basis of MU-MIMO, frame transmission and reception method.
The method of claim 1,
Transmitting the ACK frame; In
A group ACK frame including at least one of identification information and a bitmap of at least one transmitting STA transmitting the frame to the AP is transmitted,
The bitmap is composed of a plurality of bits,
Each of the plurality of bits is mapped to each of at least one transmitting STA that transmits the frame to the AP.
delete The method of claim 1,
Transmitting the ACK frame; is performed on the basis of MU-MIMO, frame transmission and reception method.
In the method for transmitting and receiving a frame for a transmission station (Station, STA) multi-user (Multi User, MU) communication,
Receiving an uplink multi-user poll (UL MU poll) frame for requesting transmission of an uplink multi-user (UL MU) from an access point (AP);
Transmitting a frame to the AP in response to the received UL MU poll frame; And
Receiving an acknowledgment (ACK) frame from the AP in response to the frame; Including,
The UL MU poll frame includes a common information field including a LENGTH field,
The LENGTH field represents the LENGTH field of the L-SIG of the frame received by the AP,
In the step of receiving the ACK frame, the received ACK frame includes at least one transmitting STA identification information that transmits the frame to the AP.
The method of claim 11,
The UL MU poll frame further includes identification information of the transmitting STA.
The method of claim 12,
The identification information of each of the transmitting STAs includes at least one of a MAC address, an Association ID (AID), and partial AID information in IEEE 802.11ac.
The method of claim 11,
The UL MU poll frame further includes information on the number of transmitting STAs that transmit the frame to the AP.
The method of claim 11,
Receiving the UL MU poll frame; is performed on the basis of the MU communication, frame transmission and reception method.
The method of claim 11,
Receiving the UL MU Poll frame; Multi User-Multi Input Multi Output (Multi User-Multi Input Multi Output, MU-MIMO) is performed on the basis of, frame transmission and reception method.
In an access point (AP) for multi-user (MU) communication,
A transceiver; And
Including a control unit for controlling the transceiver,
The control unit,
Determine at least one transmitting station (Station, STA),
Transmitting an uplink multi-user poll (UL MU poll) frame requesting transmission of an uplink multi-user (UL MU) to the at least one transmitting STA through the transceiver,
Receiving a frame from the at least one transmitting STA in response to the transmitted UL MU poll frame through the transceiver,
Transmitting an acknowledgment (ACK) frame to the at least one transmitting STA in response to the frame through the transceiver,
The UL MU poll frame includes a common information field including a LENGTH field,
The LENGTH field represents the LENGTH field of the L-SIG of the frame received by the AP,
The AP transmits at least one ACK frame, and each of the at least one ACK frame includes identification information of each of at least one transmitting STA transmitting the frame to the AP.
The method of claim 17,
The UL MU poll frame further includes identification information of each of at least one transmitting STA that transmits the frame to the AP.
In a transmitting station (Station, STA) for multi-user (MU) communication,
A transceiver; And
Including a control unit for controlling the transmission and reception unit,
The control unit,
Receiving an UL MU poll frame requesting transmission of an uplink multi-user (UL MU) from an access point (AP) through the transceiver,
Transmitting a frame to the AP in response to the received UL MU poll frame through the transceiver,
An acknowledgment (ACK) frame is received from the AP in response to the frame through the transceiver,
The UL MU poll frame includes a common information field including a LENGTH field,
The LENGTH field represents the LENGTH field of the L-SIG of the frame received by the AP,
The transmission station, wherein the received ACK frame includes at least one transmission STA identification information for transmitting the frame to the AP.
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