KR20200104272A - Method of transmitting request of uplink mu-mimo for uplink mu-mimo communication - Google Patents

Abstract

Disclosed is a frame transmission and reception method for multi user-multi input multi output (MU-MIMO) communication in an access point (AP). According to an embodiment of the present invention, a frame transmission and reception method comprises the steps of: transmitting an uplink (UL) MU request frame requesting data frame transmission to a plurality of stations; and receiving a data frame from the plurality of stations with the same reception strength for the same period. The UL MU request frame may include at least one of a transmission period of the data frame and reception strength information at the AP of the data frame.

Description

UPLINK MU-MIMO transmission request method for UPLINK MU-MIMO communication {METHOD OF TRANSMITTING REQUEST OF UPLINK MU-MIMO FOR UPLINK MU-MIMO COMMUNICATION}

The present disclosure relates to a MAC protocol of a wireless LAN, and in particular, to a structure of a frame required to transmit a frame using Uplink MU-MIMO technology.

In recent wireless communication systems, a multi-input multi-output (MIMO) technology that transmits and receives 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.

IEEE 802.11ac, which is being standardized recently, includes Downlink MU-MIMO technology in which an access point (AP) simultaneously transmits beamformed data frames to several STAs in order to use frequency resources more efficiently. In addition, studies on Uplink MU-MIMO technology in which multiple stations (STAs) simultaneously transmit beamformed data frames to APs are being conducted.

An example of a protocol used to transmit data using Uplink MU-MIMO is shown in FIG. 1.

Stations (STAs) that want to transmit data using Uplink MU-MIMO need to simultaneously transmit Beamformed Data frames, so a process for the AP to inform when to start transmission is required. This process is the UL MU Request sequence of FIG. 1. After this process is completed, the stations (STAs) transmit a beamformed data frame after a predetermined time. After the AP receives the Beamformed Data frame from several STAs, it sends an Ack or BA to each STA, which is the Ack sequence of FIG. 1. If necessary, a protection sequence for preventing channel access of other STAs in the BSS may be included before the UL MU Request sequence.

However, in order for the AP to safely receive beamformed data frames transmitted by several stations (STAs) simultaneously, the temporal length of the beamformed data frames transmitted by each station (STA), that is, the transmission period, is It should be the same, the strength of the received signal should be almost the same, and the number of spatial steams (Nss) used by each station (STA) for transmission should be known.

A frame transmission/reception method for multi-user-multi-input multi-out (MU-MIMO) communication in an access point (AP) according to an embodiment is an uplink multi-user request (UL) requesting data frame transmission to a plurality of stations. MU Request) transmitting a frame and receiving the data frame with the same reception strength for the same period from the plurality of stations, wherein the uplink multi-user request frame includes a transmission period of the data frame and the data frame It may include at least one of the reception strength information of the access point.

The uplink multi-user request frame may include identification information of each of the plurality of stations, and the identification information includes at least one of MAC address, AID, and partial AID information in IEEE 802.11ac. It can contain one.

The uplink multi-user request frame may further include information on the number of transmission stations.

A frame transmission/reception method for multi-user-multi-input multi-out (MU-MIMO) communication in a station according to another embodiment includes, from an access point, an uplink multi-user request (UL MU Request) frame requesting data frame transmission. Receiving, determining a transmission period of the data frame based on the uplink multi-user request frame, and transmitting the data frame to the access point during the determined transmission period, the uplink multi-user The request frame may include a transmission period of the data frame.

The uplink multi-user request frame may include identification information of each of the stations, and the identification information includes at least one of MAC address, AID, and partial AID information in IEEE 802.11ac. It may include.

In another embodiment, a frame transmission/reception method for multi-user-multi-input multi-out (MU-MIMO) communication in a station is an uplink multi-user request (UL MU Request) frame requesting data frame transmission from an access point. Receiving, determining a transmission strength of the data frame based on the uplink multi-user request frame, and transmitting the data frame to the access point with the determined transmission strength, and the uplink multi-user request frame The user request frame may include reception strength information at the access point of the data frame.

In the determining of the transmission strength of the data frame, the transmission strength of the data frame may be determined based on information on the reception strength of the data frame at the access point.

The uplink multi-user request frame may further include transmission strength information of the uplink multi-user request frame at the access point.

The frame transmission/reception method may further include determining a reception strength of the uplink multi-user request frame at the station.

The determining of the transmission strength of the data frame may include calculating a path loss based on the reception strength of the uplink multi-user request frame at the station and the transmission strength information of the uplink multi-user request frame at the access point. It may include the step of.

In the determining of the transmission strength of the data frame, the transmission strength of the data frame may be determined based on the path loss and reception strength information at the access point of the data frame.

According to another embodiment, a station for multi-user-multi-input multi-out (MU-MIMO) communication includes: a communication unit for receiving an uplink multi-user request (UL MU Request) frame requesting data frame transmission from an access point; And a control unit for determining a transmission period of the data frame based on the uplink multi-user request frame, and controlling the communication unit to transmit the data frame to the access point during the determined transmission period, and the uplink multi-user request frame The user request frame may include a transmission period of the data frame.

The uplink multi-user request frame may include identification information of each of the stations.

According to another embodiment, a station for multi-user-multi-input multi-out (MU-MIMO) communication includes a communication unit for receiving an uplink multi-user request (UL MU Request) frame requesting data frame transmission from an access point, and the And a control unit configured to control the communication unit to determine a transmission strength of the data frame based on an uplink multi-user request frame and transmit the data frame to the access point at the determined transmission strength, and the uplink multi-user request The frame may include information on the reception strength of the data frame at the access point.

The control unit may determine the transmission strength of the data frame based on the reception strength information of the data frame at the access point.

The uplink multi-user request frame may further include transmission strength information of the uplink multi-user request frame at the access point.

The control unit determines the reception strength of the uplink multi-user request frame at the station, and the reception strength of the uplink multi-user request frame at the station and the uplink multi-user request frame at the access point. Path loss can be calculated based on the transmission strength information.

The control unit may determine the transmission strength of the data frame based on the path loss and reception strength information of the data frame at the access point.

1 is an example of a protocol used to transmit data using Uplink MU-MIMO.
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 flowchart of a method for transmitting and receiving frames in an AP according to an embodiment.
5A is a structure of a UL MU request frame according to an embodiment.
5B is a structure of a VHT PPDU according to an embodiment.
5C is a structure of an embodiment in which VHT-SIG-A to be used for UL MU-MIMO transmission is included in a UL-MU request frame.
6 and 7 are flowcharts illustrating a method of transmitting and receiving frames at a station 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 determine at least one of a data frame transmission period and a transmission strength, for example, from the UL MU request frame. The controllers 210-1, 210-2 and 210-n may control the communication units 220-1, 220-2 and 220-n to transmit a data frame based on at least one of the determined transmission period and transmission intensity.

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 request frame (hereinafter referred to as UL MU request frame). And it can transmit and receive a data frame (data 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 transmit a UL MU request frame to the station 200. The UL MU request 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 request 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 request frame for protection. In an embodiment, the UL MU request frame may include at least one of transmission period and reception strength information of the data frame. For example, the UL MU request frame may include at least one of a UL MU request frame transmission strength of the AP 100 and a reception strength when a data frame is received by the AP 100.

In step 320, the station 200 may determine at least one of a transmission period and a transmission strength of the data frame based on the UL MU request frame.

In step 330, the station 200 may transmit the data frame based on at least one of the determined transmission period and the transmission strength.

4 is a flowchart of a method for transmitting and receiving frames in an AP according to an embodiment.

In step 410, the AP may determine transmission times of a plurality of stations.

In step 420, the AP may determine a reception strength at the AP when a plurality of stations transmit data frames.

In step 430, the AP may transmit a UL MU request frame including at least one of the determined transmission period and reception strength information to the station. For example, the structure of the UL MU request frame according to an embodiment may be the same as that of FIG. 5A.

As shown in FIG. 5A, the UL MU request 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). The UL MU request 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-MIMO common information field (UL MU-MIMO Info) includes a transmission period information field (L-LENGTH) of a data frame, an AP transmission strength information field (Tx power level), and a request reception strength information field (Requested Tx power). level) and a station number information field (# of STAs).

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.

Meanwhile, the AP transmission strength information field (Tx power level) may include information on transmission strength when the AP transmits the UL MU request frame. In addition, the requested reception strength information field (Requested Tx power level) may include information on requested reception strength when the AP receives a data frame.

The station number information field (# of STAs) indicates the number of stations that will transmit data frames during the uplink MU-MIMO transmission period. In the UL MU Request frame, the STA info field of this value is included.

In step 440, the AP may receive a data frame. The plurality of stations may transmit the data frame to the AP during the same period. In addition, a plurality of data frames transmitted by each of the plurality of stations may be received by the AP with the same strength. Here, the meaning of the same may mean that the same is temporally or intensified, or within a preset error range.

On the other hand, using Uplink MU-MIMO technology, a part of the preamble of the PHY layer constituting the PPDU transmitted by multiple STAs must be exactly the same before the AP can receive. The structure of the VHT PPDU may be the same as 5b. Among them, L-SIG, VHT-SIG-A, and VHT-SIG-B contain PHY layer control information, and VHT-SIG-B is supposed to contain different information for each spatial steam, and L-SIG and In VHT-SIG-A, all spatial streams must contain the same information.

The elements constituting the L-SIG are L-LENGTH and L-DATARATE, and the L-DATARATE of the VHT-PPDU is fixed at 6 Mbps. Therefore, the same L-SIG is provided by the method proposed in FIG. It is possible to make. In order to make the VHT-SIG-A the same, the VHT-SIG-A to be used for UL MU-MIMO transmission may be included in the UL-MU request frame, and the structure is as shown in FIG. 5C.

6 is a flowchart of a method for transmitting and receiving frames at a station according to an embodiment.

In step 610, the station may receive a UL MU request frame from the AP. The UL MU request frame may include a transmission period of a data frame.

In step 620, the station may determine a data frame transmission period from the UL MU request frame.

In step 630, the station may transmit a data frame to the AP during the determined transmission period. In addition, a plurality of stations may transmit data frames to the AP during the same period. Accordingly, the AP may receive a data frame from a plurality of stations for the same period, and stable beamforming data frame transmission and reception may be possible.

7 is a flowchart illustrating a method of transmitting and receiving frames at a station according to an embodiment.

In step 710, the station may receive a UL MU request frame from the AP. The UL MU request frame may include reception strength information of the data frame. In more detail, the UL MU request frame may include transmission strength information of the UL MU request frame at the AP and data frame reception strength information at the requested AP side.

In step 720, the station may check the transmission strength of the UL MU request frame in the AP from the UL MU request frame.

In step 730, the station may check the actual reception strength of the UL MU request frame.

In step 740, the station may calculate the path loss based on the transmission strength and the actual reception strength of the UL MU request frame at the AP.

In step 750, the station may determine the transmission strength of the data frame based on the calculated path loss. For example, the station may determine the transmission strength of the data frame at the station in consideration of the reception strength and path loss of the data frame requested from the AP.

In step 760, the station may transmit a data frame to the AP according to the determined transmission strength.

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 may 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 (12)

In the frame transmission/reception method for multi-user-multi-input multi-out (MU-MIMO) communication in an access point (AP),
Transmitting, to a plurality of stations, an uplink multi-user request (UL MU Request) frame for requesting data frame transmission; And
Receiving the data frame based on the same reception strength from the plurality of stations; Including,
The uplink multi-user request frame includes a transmission power field (Tx power field) and a requested reception power field (Requested Rx power field),
The transmission power field includes information on transmission strength applied when the access point transmits the uplink multi-user request frame, and
The requested reception power field includes information on a reception strength requested when the access point receives the data frame.
The method of claim 1,
The uplink multi-user request frame includes identification information of each of the plurality of stations.
The method of claim 2,
The identification information includes at least one of MAC address, AID, and partial AID information in IEEE 802.11ac.
The method of claim 1,
The uplink multi-user request frame further includes information on the number of transmission stations.
In a frame transmission and reception method for multi-user-multi-input multi-out (MU-MIMO) communication in a station (Station, STA),
Receiving an uplink multi-user request (UL MU Request) frame requesting data frame transmission from an access point (AP);
Determining the data frame transmission strength based on the uplink multi-user request frame; And
Transmitting the data frame based on the determined transmission strength to the access point; Including,
The uplink multi-user request frame includes a transmission power field (Tx power field) and a requested reception power field (Requested Rx power field),
The transmission power field includes information on transmission strength applied when the access point transmits the uplink multi-user request frame, and
The requested reception power field includes information on a reception strength requested when the access point receives the data frame.
The method of claim 5,
Determining the transmission strength;
Determining, at the access point, the data frame transmission strength based on information on the data frame reception strength.
The method of claim 6,
The uplink multi-user request frame further includes information on transmission strength of the uplink multi-user request frame.
The method of claim 7,
Determining the reception strength of the uplink multi-user request frame at the station;
The method of claim 8,
The step of determining the transmission strength of the data frame,
And calculating a path loss based on the reception strength of the uplink multi-user request frame at the station and the transmission strength information of the uplink multi-user request frame at the access point.
The method of claim 9,
The step of determining the transmission strength of the data frame,
A frame transmission/reception method for determining a transmission strength of the data frame based on the path loss and reception strength information at the access point of the data frame.
In an access point (AP) performing frame transmission and reception for multi-user-multi-input multi-out (MU-MIMO) communication,
A transceiver; And
Including a processor for controlling the transceiver,
The processor,
Transmitting an uplink multi-user request (UL MU Request) frame requesting data frame transmission to a plurality of stations through the transceiver,
Receiving the data frame based on the same reception strength from the plurality of stations through the transceiver,
The uplink multi-user request frame includes a transmission power field (Tx power field) and a requested reception power field (Requested Rx power field),
The transmission power field includes information on transmission strength applied when the access point transmits the uplink multi-user request frame, and
The requested reception power field includes information on a reception strength requested when the access point receives the data frame.
In a station (Station, STA) performing frame transmission and reception for multi-user-multi-input multi-out (MU-MIMO) communication,
A transceiver; And
Including a processor for controlling the transceiver,
The processor,
Receives an uplink multi-user request (UL MU Request) frame requesting data frame transmission from an access point (AP) through the transceiver,
Determine the data frame transmission strength based on the uplink multi-user request frame; And
Transmitting the data frame based on the determined transmission strength to the access point through the transceiver,
The uplink multi-user request frame includes a transmission power field (Tx power field) and a requested reception power field (Requested Rx power field),
The transmission power field includes information on transmission strength applied when the access point transmits the uplink multi-user request frame, and
The requested reception power field includes information on a reception strength requested when the access point receives the data frame.

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