WO2022219856A1

WO2022219856A1 - Communication device and communication method

Info

Publication number: WO2022219856A1
Application number: PCT/JP2021/048694
Authority: WO
Inventors: 龍一平田; 健田中; 茂菅谷
Original assignee: ソニーグループ株式会社
Priority date: 2021-04-12
Filing date: 2021-12-27
Publication date: 2022-10-20

Abstract

Provided is a communication device that performs wireless communication using a plurality of links, such that the difference between the transmission end times for the links is within a prescribed range.　This communication device comprises: a first communication unit that performs communication through a first link; a second communication unit that performs communication through a second link; and a control unit that controls communication operations, by the first communication unit and the second communication unit, using the first link and the second link. The control unit controls the transmission timing at the second link of the second communication unit when the first communication unit starts transmission first through the first link.

Description

Communication device and communication method

The technology disclosed in this specification (hereinafter referred to as "this disclosure") relates to a communication device and a communication method that perform wireless communication using a plurality of links.

Wireless communication using multiple links (Multi-link Operation: MLO) is being considered as a method to support high-resolution image data such as 8K and high transmission speed requirements such as XR (general term for VR, AR, MR, and SR). It is A "link" as used herein is a wireless transmission path through which data can be transmitted between two communication devices. When performing MLO, individual links are selected from among a plurality of mutually independent radio transmission paths, for example, divided in the frequency domain. Specifically, channels selected from among a plurality of channels included in one of frequency bands such as the 2.4 GHz band, 5 GHz band, 6 GHz band, and 920 MHz band are used.

A communication device that supports MLO is called an MLD (Multi-link Device). MLD is a logical entity containing one or more communication terminals (STation: STA), and has only one SAP (Service Access Point) to an upper layer. An MLD in which each STA included is an access point (AP) is called an AP MLD. Also, an MLD that is a STA that is not an access point, that is, a non-AP STA is called a non-AP MLD.

MLD uses multiple links for transmission, but due to factors such as the proximity of frequencies between links, the transmitted signal on one link leaks, causing strong interference with the received signal on other links and degrading communication quality. sometimes. A pair of links in which simultaneous transmission and reception on a plurality of links is thus restricted is called an NSTR (Non-Simultaneous Transmit and Receive) link pair. On the other hand, a link pair that does not have restrictions when signals are simultaneously transmitted and received between links, such as the power leakage between links not affecting communication quality, is called a STR (Simultaneous Transmit and Receive) link pair. In this specification, when AP MLD and non-AP MLD communicate using a certain link pair, that link pair is STR link pair for AP MLD, but NSTR link pair for non-AP MLD. , AP MLD is defined as STR AP MLD, and non-AP MLD is defined as NSTR non-AP MLD.

For example, when AP MLD sends DL (Downlink) PPDU (PLCP (Physical Layer Convergence Protocol) Protocol Data Unit) to NSTR non-AP MLD over multiple links, NSTR non-AP MLD will send If an ACK is returned on a terminated link, the transmitted signal may leak and interfere with received signals on other links for which transmission has not yet terminated, degrading communication quality.

For this reason, in Non-Patent Document 1, when AP MLD transmits DL PPDU to NSTR non-AP MLD over multiple links, the DL PPDU is sent to NSTR non- If the PPDU requests an immediate response from the AP MLD, the DL on each link is set so that the reception of the DL PPDU in NSTR non-AP MLD and the transmission of the immediate response after the SIFS that has completed the DL PPDU reception do not occur at the same time. It is determined that PPDUs should be transmitted so that the difference between the transmission end times of the PPDUs is within a predetermined range.

An object of the present invention is to provide a communication device and a communication method that perform wireless communication using a plurality of links so that the difference between the transmission end times of each link is within a predetermined range.

The present disclosure has been made in consideration of the above problems, and the first aspect thereof is
a first communication unit that communicates over a first link;
a second communication unit that communicates over a second link;
a control unit that controls communication operations using the first link and the second link by the first communication unit and the second communication unit;
and
The control unit controls transmission timing on the second link of the second communication unit when the first communication unit starts transmission on the first link first.
A communication device.

The control unit controls transmission timing on the second link based on information regarding transmission data that the first communication unit has started transmission and information regarding transmission data that is scheduled to be transmitted by the second communication unit. . The information about the transmission data includes at least OFDM symbol length, number of OFDM symbols, transmission start time (including scheduled transmission start time).

When a difference between a transmission end time on the first link by the first communication unit and a scheduled transmission end time on the second link by the second communication unit is equal to or greater than a predetermined value, the control unit The transmission timing is controlled such that the difference between the transmission end time and the expected transmission end time is less than a predetermined value.

A second aspect of the present disclosure is a communication method in which a communication device communicates using a first link and a second link,
initiating transmission on the first link first;
controlling the transmission timing on the second link so that the difference between the transmission end time on the first link and the scheduled transmission end time on the second link is less than a predetermined value;
is a communication method having

Advantageous Effects of Invention According to the present disclosure, it is possible to provide a communication device and a communication method that, when performing wireless communication using a plurality of links, align the transmission end times of each link by adjusting the transmission timing on a specific link. .

It should be noted that the effects described in this specification are merely examples, and the effects brought about by the present disclosure are not limited to these. In addition, the present disclosure may have additional effects in addition to the effects described above.

Further objects, features, and advantages of the present disclosure will become apparent from more detailed descriptions based on the embodiments described later and the accompanying drawings.

FIG. 1 is a diagram showing a configuration example of a communication system. FIG. 2 is a diagram showing a functional configuration example of the communication device 200. As shown in FIG. FIG. 3 is a flow chart showing a processing procedure for implementing MLO so that the transmission end times of a plurality of links are aligned. FIG. 4 is a diagram showing a configuration example of a frame including Capability information. FIG. 5 is a diagram showing a communication sequence in which AP MLD adjusts transmission timing on a specific link in order to align transmission end times between links. FIG. 6 is a diagram showing OFDM symbols used in the PPDU format before IEEE 802.11ax and OFDM symbols used in the PPDU format after IEEE 802.11ax.

The present disclosure will be described in the following order with reference to the drawings.

A. System configurationB. Device configuration of communication deviceC. Send operationD. Communication sequence exampleE. effect

A. System Configuration FIG. 1 schematically shows a configuration example of a communication system to which the present disclosure is applied. The illustrated communication system consists of AP MLD and Non-AP MLD, and implements MLO. The AP MLD is a communication device equivalent to a base station that supports MLO. Also, the Non-AP MLD is a communication device equivalent to a terminal compatible with MLO. Non-AP MLDs are connected to AP MLDs by multiple links. In FIG. 1, the solid and broken lines drawn between the AP MLD and the non-AP MLD respectively indicate different links (link1, link2) wirelessly connecting the AP MLD and the non-AP MLD.

The links used in the communication system shown in FIG. 1 are radio transmission lines that can transmit data between two communication devices, and each link is a plurality of independent radio transmission lines divided in the frequency domain, for example. (channel). A link can be two channels selected from the same frequency band or two channels selected from different frequency bands. Also, the number of links used between AP MLD and Non-AP MLD is not limited to two, and communication may be performed using three or more links.

In this embodiment, it is also assumed that data frames in formats with different OFDM (Orthogonal Frequency Division Multiplexing) symbol lengths are transmitted for each link. For example, on one link, non-HE PPDU based on the format before IEEE802.11ax (hereinafter also referred to as "non-HE (High-Efficiency) PPDU") is transmitted, and on the other link, IEEE802.11ax or later Format-based HE/EHT PPDU (HE PPDU or EHT (Extreme High Throughput) PPDU, hereinafter referred to as "HE/EHT PPDU") (see Non-Patent Document 2) is transmitted I assume.

B. Device Configuration of Communication Device FIG. 2 shows an example of the internal configuration of the communication device 200 . The communication device 200 is a communication device compatible with MLO, and is assumed to operate as AP MLD or Non-AP MLD in the communication system shown in FIG. The communication device 200 mainly includes a communication section 210 , a control section 220 , a storage section 230 and an antenna 240 . The communication unit 210 includes a communication control unit 211, a communication storage unit 212, a data processing unit including a common data processing unit 213 and an individual data processing unit 214, a signal processing unit 215, and a wireless interface (IF) unit 216. , and an amplifier 217 .

An individual data processing unit 214, a signal processing unit 215, a radio interface (IF) unit 216, an amplifier unit 217, and an antenna 240 are provided for each link. It is assumed that communication device 200 implements MLO using two links, a first link and a second link. For example, an individual data processing unit 214-1, a signal processing unit 215-1, a wireless interface unit 216-1, an amplifier unit 217-1, and an antenna 240-1 are set as an individual communication set for transmission/reception processing in the first link, Separate data processing unit 214-2, signal processing unit 215-2, wireless interface unit 216-2, amplifier unit 217-2, and antenna 240-2 are used as another separate communication set for transmission/reception processing on the second link. . For example, one dedicated communication set transmits and receives non-HE PPDUs based on IEEE 802.11ax and earlier formats on the first link, and the other dedicated communication set transmits and receives IEEE 802.11ax and later formats on the second link. based HE/EHT Send and receive PPDU.

The communication control unit 211 controls the operation of each unit in the communication unit 210 and information transmission between the units. Further, the communication control unit 211 transfers control information and management information to be notified to other communication devices to the data processing units (common data processing unit 213, individual data processing unit 214-1 and individual data processing unit 214-2). control.

In the present disclosure, the communication control unit 211 includes a first individual control unit and a second individual control unit that control each individual communication set, a common data processing unit, and common control for each individual communication set. A common control exists. Each individual control unit conveys control information (OFDM symbol length, etc.) regarding the transmission data unit to the other individual control units. At this time, it may be transmitted via the common control unit.

The communication storage unit 212 holds information used by the communication control unit 211. Further, the communication storage unit 212 holds data transmitted by the communication device 200 and data received by the communication device 200 .

At the time of transmission, the common data processing unit 213 performs sequence management of the data held in the communication storage unit 212 and the control information and management information received from the communication control unit 211, and performs encryption processing and the like to generate data units. , to the individual data processing units 214-1 and 214-2. Also, the common data processing unit 213 performs decoding processing and reordering processing of the data unit at the time of reception.

At the time of transmission, the individual data processing units 214-1 and 214-2 perform channel access operations based on carrier sense on the respective corresponding links, and add MAC (Media Access Control) headers and error detection codes to data to be transmitted. , and multiple concatenation processing of data units. In addition, the individual data processing units 214-1 and 214-2 perform decoupling processing, analysis and error detection, and retransmission request operation of the MAC headers of the data units received on the respective corresponding links at the time of reception.

The operations of the common data processing unit 213 and the individual data processing units 214-1 and 214-2 are not limited to the above. 2, one of the individual data processing units 214-1 and 214-2 performs at least part of the operation of the common data processing unit 213, and one of the individual data processing units 214-1 and 214-2 performs It is also possible to perform the other operation.

At the time of transmission, the signal processing units 215-1 and 215-1-2 perform encoding, interleaving, modulation, etc. on data units, add physical headers, and generate symbol streams. Also, upon reception, the signal processing units 215-1 and 215-2 analyze the physical header, demodulate, deinterleave, and decode the symbol stream, and generate data units. Signal processing sections 215-1 and 215-2 also perform complex channel characteristic estimation and spatial separation processing as necessary.

At the time of transmission, the radio interface units 216-1 and 216-2 perform digital-analog signal conversion, filtering, up-conversion, and phase control on the symbol stream to generate transmission signals. Also, the radio interface units 216-1 and 216-2 perform down-conversion, filtering, and analog-to-digital signal conversion on the received signals at the time of reception to generate symbol streams.

The amplification sections 217-1 and 217-2 power-amplify the signals input from the wireless interface sections 216-1 and 216-2 during transmission. Further, amplifiers 217-1 and 217-2 perform low-noise amplification on signals input from antennas 240-1 and 240-2 during reception. Part of the amplifying units 217-1 and 217-2 may be components outside the communication unit 210. FIG. Also, part of the amplification units 217-1 and 217-2 may be included in the radio interface units 216-1 and 216-2.

The control unit 220 controls the communication unit 210 and the communication control unit 211. Also, the control unit 220 may perform part of the operation of the communication control unit 211 instead. Also, the communication control unit 211 and the control unit 220 may be configured as one block.

The storage unit 230 holds information used by the communication unit 210 and the control unit 220. Storage unit 230 may perform part of the operation of communication storage unit 212 instead. Storage unit 230 and communication storage unit 212 may be configured as one block.

The individual data processing unit 214-1, the signal processing unit 215-1, the wireless interface unit 216-1, the amplifier unit 217-1, and the antenna 240-1 are regarded as one individual communication set, and wireless communication is performed on the first link. do. Further, the individual data processing unit 214-2, the signal processing unit 215-2, the wireless interface unit 216-2, the amplifier unit 217-2, and the antenna 240-2 are used as another individual communication set, and wireless communication is performed on the second link. to implement. Although only two individual communication sets are depicted in FIG. 2, three or more individual communication sets may be components of communication device 200, each individual communication set performing wireless communication on a respective link. can also Also, memory 230 or communication memory 212 may be included in each individual communication set.

A link is a radio transmission line that can transmit data between two communication devices, and each link is selected from among a plurality of mutually independent radio transmission lines (channels) divided in the frequency domain, for example. . The links used by each individual communication set may be two channels selected from the same frequency band or two channels selected from different frequency bands. Alternatively, the individual data processing unit 214 and the signal processing unit 215 may be set as one set, and two or more sets may be connected to one common wireless interface unit 216 .

The wireless interface unit 216, the amplifier unit 217, and the antenna 240 may be one set, and two or more sets may be components of the communication device 200.

The communication unit 210 can also be configured by one or more LSIs (Large Scale Integration).

The common data processing unit 213 is also called Upper MAC or Higher MAC, and the individual data processing unit 214 is also called Lower MAC. A set of the individual data processing unit 214 and the signal processing unit 215 is also called an AP entity or a non-AP entity. The communication control unit 211 is also called an MLD management entity.

Also, in this specification, functional blocks (or individual communication sets) from the antenna 240 to the individual data processing unit 214 and individual control unit are collectively referred to as STA.

In this embodiment, it is also assumed that the communication device 200 transmits data frames in formats with different OFDM symbol lengths for each link. For example, non-HE PPDUs based on IEEE802.11ax and earlier formats are transmitted on the first link, and HE/EHT PPDUs based on IEEE802.11ax and later formats are transmitted on the second link.

C. For example, when AP MLD transmits DL PPDU (Physical layer Protocol Data Unit) to NSTR non-AP MLD through multiple links, NSTR non-AP MLD sends ACK ( If an attempt is made to return "immediate response", the transmitted signal may leak and interfere with received signals on other links for which transmission has not yet been completed, degrading communication quality.

For this reason, in Non-Patent Document 1, when AP MLD transmits DL PPDU to NSTR non-AP MLD over multiple links, the DL PPDU is sent to NSTR non- If the PPDU requests an immediate response from the AP MLD, the DL PPDU is sent so that the NSTR non-AP MLD does not receive the DL PPDU and send the immediate response after the SIFS that has completed the DL PPDU reception at the same time. The difference between the end times should be within 8 microseconds (however, if the frame requests the return of the PPDU to the destination and includes a frame that requests carrier sense before the transmission of the PPDU to the destination (specifically, If the DL PPDU contains a Trigger frame, the CS Required subfield in the Trigger frame is set to 1, and carrier sense is requested before sending the PPDU induced by the Trigger), it is possible to send the difference within 4 microseconds). It is decided.

However, the OFDM symbol length differs between the PPDU transmitted in the format before IEEE802.11ax and the PPDU transmitted in the format after IEEE802.11ax. FIG. 6 shows OFDM symbols used in the PPDU format before IEEE 802.11ax and OFDM symbols used in the PPDU format after IEEE 802.11ax. Specifically, the non-HE PPDU has a GI (Guard Interval) of 0.4 microseconds or 0.8 microseconds inserted into an OFDM symbol of 3.2 microseconds, and the length per symbol is 3.2 microseconds. It will be either 6 microseconds or 4.0 microseconds (see FIGS. 6A and 6B). On the other hand, in the data portion of HE/EHT PPDU, GI of 0.8 microseconds, 1.6 microseconds or 3.2 microseconds is inserted into OFDM symbols of 12.8 microseconds. The length of one symbol is either 13.6 microseconds, 14.4 microseconds, or 16.0 microseconds (see FIGS. 6(C)-(E)). For this reason, non-HE PPDU based on IEEE802.11ax format or earlier are transmitted on one link, and HE/EHT PPDU based on IEEE802.11ax or later format are simultaneously transmitted on the other link to align the transmission end times. In some cases, a deviation of 8 microseconds (or 4 microseconds) or more occurs due to the difference in the number of symbols. For example, even if the number of MPDUs to be aggregated in non-HE PPDU based on the IEEE802.11ax format or earlier is adjusted or padding is performed, the HE/EHT PPDU transmission end time based on the IEEE802.11ax or later format It is assumed that there will be a situation in which the transmission end time is earlier than 8 microseconds (or 4 microseconds) or more.

Therefore, in the present disclosure, for example, in the communication system that implements MLO shown in FIG. 1, when AP MLD transmits PPDU with different OFDM symbol lengths to non-AP MLD, the transmission end time Information on the transmission start time of the previously transmitted PPDU and the number of OFDM symbols is shared between the links so that they are aligned. Therefore, according to the present disclosure, the AP MLD can adjust the transmission timing of the PPDU on the other link so that the transmission ends at the same time as the PPDU that started transmission earlier, based on the information shared between the links. . As a result, if the destination non-AP MLD is NSTR, the communication quality will deteriorate due to the interference between the transmitted signal sent back on the link that has completed transmission earlier and the received signal on other links that have not yet completed transmission. Deterioration can be prevented.

FIG. 3 shows, in the form of a flowchart, a processing procedure for the communication device 200 (for example, AP MLD) to implement MLO so that the transmission end times of a plurality of links are aligned.

First, Capability information is exchanged between MLDs (step S301).

Next, when a certain STA within the MLD acquires the transmission right and starts transmitting the PPDU, the STAs within the MLD exchange information regarding the length of the PPDU (step S302).

Next, using the information on the transmission PPDU and the information on the scheduled transmission PPDU, it is determined whether or not to control the transmission end time of the PPDU of other STAs (step S303).

Then, in preceding step S303, when it is determined that the PPDU transmission end time of the other STA is to be controlled (Yes in step S303), the PPDU transmission timing of the other STA is controlled (step S304).

Next, each step in the flowchart shown in FIG. 3 will be described in detail.

Step S301: Capability information exchange The capability information exchanged in step S301 includes the following information.

(1) Whether or not the PPDU transmission timing can be controlled in order to adjust the PPDU transmission end time.
(2) whether or not the pair of links can transmit and receive simultaneously (either STR or NSTR);
(3) Number of links available (4) Number of radios available

The following can be cited as places to describe the above Capability information. Also, FIG. 4 shows a configuration example of a frame including capability information.

(1) In the MLD common Info field that stores information about MLD in the multi-link element.
(2) In the STAn Info field that stores information for each STA in the Multi-Link element.

In addition, the timing for exchanging Capability information is as follows.

(1) At connection establishment between MLDs.
(2) When transmitting/receiving a beacon.
(3) When sending data.

Step S302: Exchanging information about PPDU length In step S302, when a certain STA in the MLD acquires the transmission right and starts transmitting the PPDU, the STAs in the MLD exchange information about the PPDU length. . Information regarding the length of the PPDU exchanged between STAs in the MLD includes the following.

(1) Number of OFDM symbols (2) OFDM symbol length (guard interval length)
(3) Transmission start time (may be scheduled transmission start time)
(4) Length of Padding The length of Padding is, for example, the following length.
(4-1) Length of Paddig field in Trigger frame (4-2) Length of Post-EOF A-MPDU (MAC Protocol Data Unit) padding (4-3) Length of Packet extension field (5) MCS (Modulation and Coding Scheme)
(6) Number of aggregated MPDUs (7) Transmission bandwidth (8) Number of transmission streams (9) Coding method (10) PPDU format (11) In a frame requesting the return of PPDU to the destination , whether or not a frame requesting carrier sense is included before transmission of the destination PPDU.
(11-1) Whether or not a Trigger frame with CS Required subfield=1 is included (11-2) Whether or not RTS (Request To Send) (12) Transmission power (13) Whether or not there is a Signal extension ( 14) How many LTFs (Long Training Fields) are included (15) Whether high priority frames are included

Step S303: Determining execution of transmission end time control In step S303, it is determined whether or not to control the transmission end time of PPDUs of other STAs using the information on the transmission PPDU and the information on the scheduled transmission PPDU.

The following can be cited as information about the PPDU scheduled to be transmitted, which is used for determining whether to control the PPDU transmission end time.

(1) Number of OFDM symbols (2) OFDM symbol length (guard interval length)
(3) Transmission start time (may be scheduled transmission start time)
(4) Length of Padding The length of Padding is, for example, the following length.
(4-1) Length of paddig field in trigger frame (4-2) Length of Post-EOF A-MPDU padding (4-3) Length of packet extension field (5) MCS (Modulation and Coding Scheme)
(6) Number of aggregated MPDUs (7) Transmission bandwidth (8) Number of transmission streams (9) Coding method (10) PPDU format (11) In a frame requesting the return of PPDU to the destination , whether or not a frame requesting carrier sense is included before transmission of the destination PPDU.
(11-1) Whether or not a Trigger frame with CS Required subfield=1 is included (11-2) Whether or not RTS (Request To Send) (12) Transmission power (13) Whether or not there is a Signal extension ( 14) How many LTFs are included (15) Whether high priority frames are included (16) Number of frames in the buffer for each access category (17) Number of retransmissions (18) PPDU transmission Information about access delays on planned links

The determination of whether to control the PPDU transmission end time is made based on at least one of the information on the Capability information acquired in step S301, the information on the transmission PPDU acquired in step S302, and the information on the scheduled transmission PPDU.

As a prerequisite for the AP MLD to control the PPDU transmission end time, the AP MLD itself must have the capability to control the PPDU transmission timing in order to adjust the PPDU transmission end time.

Also, the fact that the pair of links on which MLO is performed is an NSTR link pair for the non-AP MLD of the destination may also be a prerequisite for implementing control of the PPDU transmission end time. If it is a STR link pair for non-AP MLD, even if the transmission end times of link1 and link2 do not match, the communication quality will not deteriorate due to inter-link interference. This is because there is no need to adjust the time.

Then, basically, the transmission end time of the transmission PPDU is calculated based on the information on the transmission PPDU, and the scheduled transmission end time of the transmission PPDU is calculated based on the information on the transmission PPDU. The time difference is calculated, and if the time difference is equal to or greater than a predetermined time difference, it is determined that PPDU transmission timing control should be performed. If the frame that requests the return of the PPDU to the destination includes a frame that requests the carrier sense before the transmission of the PPDU to the destination, the predetermined time difference is set to 4 microseconds; sets the predetermined time difference to 8 microseconds.

Here, the types of frames included in the transmission PPDU or the transmission-scheduled PPDU may be determined to determine whether or not to perform PPDU transmission timing control. For example, if the transmission PPDU whose transmission ends earlier includes a frame with a higher priority, it may be determined not to perform the transmission timing control of the PPDU. This is to avoid a delay in the transmission end time of a high-priority frame due to adjustment of transmission timing due to unnecessary padding or the like.

Step S304: Transmission timing control When it is determined in step S303 that control of the PPDU transmission end time of another STA is to be performed, PPDU transmission timing control is performed.

Basically, as a method of controlling the transmission timing of PPDU, after another STA acquires the transmission right of the link, the time to start transmitting PPDU is delayed, and transmission by each STA (that is, each link) is performed. Ensure that the difference between the end times is within a predetermined time. If the frame requesting the transmission destination to return the PPDU includes a frame requesting carrier sense before the transmission of the PPDU to the transmission destination, the predetermined time is 4 microseconds. Time is set to 8 microseconds.

Also, after another STA acquires the transmission right and before it transmits the PPDU, a signal may be transmitted on that link to suppress acquisition of the transmission right on that link by another MLD. Signals to be transmitted include the following.

(1) CTS (Clear To Send)-to-self frame (2) RTS frame (3) Busy tone

D. Communication sequence example In this section D, the PPDU to be transmitted first by the AP MLD is the EHT/HE PPDU, the PPDU to be subsequently transmitted is the non-HE PPDU, the transmission start time of the EHT/HE PPDU, the OFDM symbol length and the number of OFDM symbols are shared between links to adjust the transmission start time of non-HE PPDU.

FIG. 5 shows a communication sequence in which AP MLD adjusts the transmission timing on a specific link in order to align the transmission end times between links. Specifically, FIG. 5 shows a communication sequence example when the STR AP MLD containing STA1 and STA2 transmits DL PPDU to the NSTR non-AP MLD. However, the link used by STA1 is link1, and the link used by STA2 is link2. It is also assumed that the PPDU transmitted by STA1 is EHT/HE PPDU (PPDU1) and the PPDU transmitted by STA2 is non-HE PPDU (PPDU2). It is assumed that the PPDU transmitted first by STA1 does not include a high-priority frame.

Before the start of the communication sequence shown in FIG. 5, for example, when the AP MLD is connected to the destination non-AP MLD, the pair of link1 and link2 is the STR link pair for the AP MLD and the NSTR link pair for the non-AP MLD. Capability information indicating that is is exchanged. Furthermore, Capability information indicating whether or not it is possible to delay the transmission start time of the PPDU and to transmit or receive it is exchanged. For non-AP MLD, if the pair of link1 and link2 is not an NSTR link pair (that is, it is a STR link pair), even if the transmission end times of link1 and link2 do not match, the communication quality due to inter-link interference Therefore, there is no need to share information between links or adjust transmission start times.

In the communication sequence shown in FIG. 5, first, PHY-TXSTART. Send a primitive called request (TXVECTOR) to request the start of PSDU (Physical layer Service Data Unit) transmission.

At the time of this transmission start request, PHY-TXSTART. In PHY-TXSTART.request, TIME_OF_DEPARTURE_REQUESTED=true is set, and information about the transmission start time is sent from PHY sublayer #1 to MAC lower sublayer #1. Set as described in confirm(TXSTATUS).

The PHY sublayer #1 of STA1 uses PHY-TXSTART. The MAC Lower Sublayer #1 is notified of information about the transmission start time by confirm (TXSTATUS). Here, the information regarding transmission start is TIME_OF_DEPARTURE, TIME_OF_DEPARTURE_ClockRate, and TX_START_OF_FRAME_OFFSET. TIME_OF_DEPARTURE is a value in the range 0 to 2 ³² −1 in units of 1/TIME_OF_DEPARTURE_ClockRate and indicates the time when the energy of the frame was sent out from the antenna. TIME_OF_DEPARTURE_ClockRate is a value in the range 0 to 2 ¹⁶ -1 expressed in MHz. TX_START_OF_FRAME_OFFSET is a value in the range 0 to 2 ³² −1 expressed in units of 10ns and is an estimate of the time when the preamble started to be transmitted from the antenna and the time until this primitive is sent to MAC lower sublayer #1. is. As a result, the MAC lower sublayer #1 of STA1 can accurately know the time when the PHY sublayer #1 started transmitting the frame.

Next, MAC lower sublayer #1 of STA1 notifies MAC lower sublayer #2 of STA2 of information about the PPDU (PPDU1 in FIG. 5) that STA1 is sending through Common entity. The information about PPDU1 includes the number of OFDM symbols in PPDU1, the length of one OFDM symbol, the length of PE (Packet Extension) field, the transmission start time, and the trigger frame with CS required=1 in PPDU1. This is information indicating whether or not the

MAC lower sublayer #2 of STA2 determines the transmission end time of PPDU1 ( T ₁ ) can be calculated. When the MAC lower subscriber #2 of STA2 transmits PPDU2 at the scheduled time to acquire the transmission right, the transmission end time (T ₂ ) of PPDU2 is set to be within a predetermined time after the transmission end time (T ₁ ) of PPDU1. Adjust the number of MPDUs aggregated into and perform padding. The predetermined time here means 8 microseconds if the trigger frame with CS required=1 is not included in PPDU1 (that is, the transmission end time T ₂ of PPDU2 is within T ₁ +8 microseconds). If so, it is 4 microseconds (that is, the transmission end time T ₂ of PPDU2 is within T ₁ +8 microseconds).

Then, when the number of MPDUs to be aggregated is adjusted and padding is performed, and PPDU2 is configured so that the transmission of PPDU2 is completed within _a predetermined time after the transmission end time T1 of PPDU1, STA2: PPDU2 is transmitted as it is without controlling the transmission timing in link2.

On the other hand, even if the number of MPDUs to be aggregated is adjusted and padding is performed, the transmission end time T ₂ of PPDU 2 is earlier than the transmission end time T ₁ of PPDU 1 by a predetermined time or more, and only a short PPDU 2 can be configured (within PPDU 1 If the Trigger frame with CS required = 1 is not included in T ₁ -8 microseconds or less, and if it is included, only a PPDU with a length of T ₁ -4 microseconds or less can be configured), Control the transmission timing in link2.

Specifically, after MAC lower subscriber # ₂ of STA2 acquires the transmission right on link2, after the transmission end time T2 of _PPDU2 is shorter than the transmission end time T1 of PPDU1 by a predetermined time (CS If the Trigger frame with required=1 is not included, after T ₁ -8 microseconds, if it is included, after T ₁ -4 microseconds), PHY-TXSTART. Send request(TXVECTOR) to PHY sublayer #2.

By implementing such transmission timing control, the time at which PHY subscriber #2 of STA2 starts transmitting PPDU2 is delayed. As a result, it is possible to perform transmission so that the difference between the transmission end time of PPDU2 and the transmission end time of PPDU1 is within a predetermined time.

Although not shown in FIG. 5, while waiting for transmission on link2, a CTS-to-self frame, an RTS frame, or a busy tone is transmitted to acquire the transmission right for link2 by another MLD. You may make it suppress.

Also, although not shown in FIG. 5, when the PPDU to be transmitted first is the non-HE PPDU and the PPDU to be subsequently transmitted is the HE/EHT PPDU, in the same manner as above, the MAC of STA2 Lower sublayer #2 can also adjust the transmission end time of PPDU2 in accordance with the transmission end time of PPDU1.

E. Effects This section E summarizes the effects brought about by the present disclosure.

According to the present disclosure, sharing information about the length of PPDU to be transmitted on a certain link within the MLD so that transmission of non-HE PPDU (or HE/EHT PPDU) transmitted later ends at the same time. Transmission timing can be adjusted. Therefore, even when transmitting PPDUs with different OFDM symbol lengths to NSTR MLD, PPDUs can be generated and transmitted so as to meet the end time alignment requirements, and reception failure due to inter-link interference in NSTR MLD can be prevented. can be prevented.

Specifically, when MLO is performed between AP MLD and non-AP MLD, when AP MLD transmits PPDUs with different OFDM symbol lengths to non-AP MLD, the transmission end times are aligned between links. , the transmission start time and the number of OFDM symbols of the previously transmitted PPDU are shared among the links. Therefore, based on the shared information, it is possible to adjust the transmission timing of the PPDU whose transmission starts later on the other link so that the transmission ends at the same time as the PPDU whose transmission started earlier on the other link. Therefore, the NSTR non-AP MLD on the receiving side can avoid a situation in which the other link fails to receive the DL PPDU due to simultaneous transmission of the immediate response on one link.

The present disclosure has been described in detail above with reference to specific embodiments. However, it is obvious that those skilled in the art can modify or substitute the embodiments without departing from the gist of the present disclosure.

In this specification, multi-link operation is performed by pairing a link on which non-HE PPDU based on IEEE 802.11ax format or earlier is transmitted and a link on which HE/EHT PPDU based on IEEE 802.11ax or later format is transmitted. Although the embodiment in which the present disclosure is applied to a communication system has been mainly described, the gist of the present disclosure is not limited to this. The effect of applying the present disclosure to various types of communication systems that perform multilink operation by pairing links that transmit data frames of different formats, and similarly aligning the transmission end times between the links through transmission timing adjustment. can be obtained.

In short, the present disclosure has been described in the form of an example, and the content of the specification should not be construed in a restrictive manner. In order to determine the gist of the present disclosure, the scope of the claims should be considered.

It should be noted that the present disclosure can also be configured as follows.

(1) a first communication unit that communicates over a first link;
a second communication unit that communicates over a second link;
a control unit that controls communication operations using the first link and the second link by the first communication unit and the second communication unit;
and
The control unit controls transmission timing on the second link of the second communication unit when the first communication unit starts transmission on the first link first.
Communication device.

(2) The control unit determines transmission timing on the second link based on information on transmission data that the first communication unit has started transmission and information on transmission data scheduled to be transmitted by the second communication unit. to control the
The communication device according to (1) above.

(3) the information about the transmission data includes at least OFDM symbol length, number of OFDM symbols, transmission start time (including scheduled transmission start time);
The communication device according to (2) above.

(4) When the difference between the transmission end time on the first link by the first communication unit and the scheduled transmission end time on the second link by the second communication unit is equal to or greater than a predetermined value, the control unit and controlling the transmission timing so that the difference between the transmission end time and the scheduled transmission end time is less than a predetermined value.
The communication device according to any one of (1) to (3) above.

(5) determining the predetermined value based on whether or not the frame requesting the transmission destination to return the frame includes a frame requesting carrier sense before transmission of the transmission destination frame;
The communication device according to (4) above.

(6) The control unit controls the transmission timing based on whether the first communication unit or the second communication unit has the capability to control the transmission timing for adjusting the transmission end time. determine whether to implement
The communication device according to any one of (1) to (5) above.

(7) The control unit determines whether or not to control the transmission timing based on the capability information of the communication device to which data is transmitted using the first link and the second link. ,
The communication device according to any one of (1) to (6) above.

(8) The control unit controls the transmission timing when the first link and the second link are a pair of links that imposes restrictions on simultaneous transmission and reception for the communication device of the transmission destination. determine whether to
The communication device according to (7) above.

(9) The control unit receives information about transmission data that the first communication unit has previously started transmitting on the first link, or transmission that the second communication unit is scheduled to transmit on the second link. Determining whether to control the transmission timing based on information about the data;
The communication device according to any one of (1) to (8) above.

(10) The control unit controls the type of transmission data that the first communication unit has previously started transmission over the first link or the transmission data that the second communication unit is scheduled to transmit over the second link. Determining whether to control the transmission timing based on the type;
The communication device according to (9) above.

(11) The control unit determines not to control the transmission timing when the transmission data whose transmission ends earlier includes data with a higher priority.
The communication device according to (10) above.

(12) The control unit controls the transmission timing by delaying the time to start transmission after the second communication unit acquires the transmission right on the second link.
The communication device according to any one of (1) to (11) above.

(13) The control unit causes the second communication unit to transmit a signal over the second link after the second communication unit acquires the transmission right over the second link and before it starts transmitting.
The communication device according to (12) above.

(14) one of the first communication unit or the second communication unit transmits HE/EHT PPDUs, and the other transmits non-HE PPDUs;
The communication device according to any one of (1) to (13) above.

(15) A communication method in which a communication device communicates using a first link and a second link,
initiating transmission on the first link first;
controlling the transmission timing on the second link so that the difference between the transmission end time on the first link and the scheduled transmission end time on the second link is less than a predetermined value;
communication method.

DESCRIPTION OF SYMBOLS 200... Communication apparatus 210... Communication part 211... Communication control part 212... Communication memory part 213... Common data processing part 214... Individual data processing part 215... Signal processing part 216... Wireless interface part 217... Amplifier, 220... Control unit 230... Storage unit 240... Antenna

Claims

a first communication unit that communicates over a first link;
a second communication unit that communicates over a second link;
a control unit that controls communication operations using the first link and the second link by the first communication unit and the second communication unit;
and
The control unit controls transmission timing on the second link of the second communication unit when the first communication unit starts transmission on the first link first.
Communication device.
The control unit controls transmission timing on the second link based on information regarding transmission data that the first communication unit has started transmission and information regarding transmission data that is scheduled to be transmitted by the second communication unit. ,
A communication device according to claim 1 .
The information about the transmission data includes at least OFDM symbol length, number of OFDM symbols, transmission start time (including scheduled transmission start time),
3. A communication device according to claim 2.
When a difference between a transmission end time on the first link by the first communication unit and a scheduled transmission end time on the second link by the second communication unit is equal to or greater than a predetermined value, the control unit controlling the transmission timing so that the difference between the transmission end time and the expected transmission end time is less than a predetermined value;
A communication device according to claim 1 .
determining the predetermined value based on whether or not a frame requesting a frame to be returned to the destination includes a frame requesting carrier sense before transmission of the frame to the destination;
5. A communication device according to claim 4.
The control unit controls the transmission timing based on whether the first communication unit or the second communication unit has the capability to control the transmission timing for adjusting the transmission end time. determine whether or not
A communication device according to claim 1 .
The control unit determines whether or not to control the transmission timing based on the capability information of the communication device to which the data is transmitted using the first link and the second link.
A communication device according to claim 1 .
The control unit determines whether or not to control the transmission timing when the first link and the second link are a pair of links that imposes restrictions on simultaneous transmission and reception for the communication device of the transmission destination. determine whether
8. A communication device according to claim 7.
The control unit provides information about transmission data that the first communication unit has previously started transmitting on the first link, or information about transmission data that the second communication unit is scheduled to transmit on the second link. Determining whether to control the transmission timing based on
A communication device according to claim 1 .
Based on the type of transmission data that the first communication unit has previously started transmission over the first link or the type of transmission data that the second communication unit is scheduled to transmit over the second link to determine whether or not to control the transmission timing;
A communication device according to claim 9 .
The control unit determines not to control the transmission timing when the transmission data whose transmission ends first includes data with a high priority.
11. A communication device according to claim 10.
The control unit delays the time to start transmission after the second communication unit acquires the transmission right on the second link, and controls the transmission timing.
A communication device according to claim 1 .
The control unit causes a signal to be transmitted on the second link after the second communication unit acquires the transmission right on the second link and before it starts transmission.
13. A communication device according to claim 12.
One of the first communication unit or the second communication unit transmits HE/EHT PPDUs, and the other transmits non-HE PPDUs;
A communication device according to claim 1 .
A communication method in which a communication device communicates using a first link and a second link,
initiating transmission on the first link first;
controlling the transmission timing on the second link so that the difference between the transmission end time on the first link and the scheduled transmission end time on the second link is less than a predetermined value;
communication method.