COMMUNICATION DEVICE AND COMMUNICATION METHOD

A communication device that performs multi-link and multi-user communication is provided. A communication device includes a communication unit capable of wirelessly communicating on a plurality of links, a communication processing unit that performs processing of simultaneously transmitting data to a plurality of reception-side communication devices, and a control unit that performs control to transmit data using an optimum link to each of the plurality of reception-side communication devices. The control unit performs control to transmit a trigger request signal for requesting information regarding a reception opportunity from the plurality of reception-side communication devices on a link on which a transmission opportunity has been acquired, and determine an optimum link for each reception-side communication device on the basis of a request response signal from the plurality of reception-side communication devices.

TECHNICAL FIELD

The technology disclosed in the present description (hereinafter, “the present disclosure”) relates to a communication device and a communication method for performing wireless communication.

BACKGROUND ART

With an increase in use of a wireless local area network (LAN) system and an increase in content capacity, communication of a predetermined data amount is getting insufficient in a case where a channel of only one frequency band is used. Therefore, as a technical study for a successor standard of IEEE 802.11ax, a method of performing higher-density data communication using a plurality of frequency bands (links) in parallel, specifically, a multi-link operation (MLO) technology of collectively transmitting a group of contents using a plurality of frequency bands (links) is studied in a task group TG be of IEEE.

In this multi-link operation, there is a demand for a technology that regards a plurality of frequency bands (links) as one transmission path and uses the transmission path for communication. In the technology, although a device of Enhanced Multi-Link Multi Radio (EMLMR) is assumed as a device including a plurality of wireless communication units so that transmission and reception can be performed simultaneously on all links, a device of Enhanced Multi-Link Single Radio (EMLSR) is also assumed as a configuration of a communication device that can perform only transmission or reception on one link. In a network of an actual wireless LAN system, it is also assumed that these two types are mixed.

In conventional multi-link operation, a configuration in which both an access point and a communication terminal simultaneously perform communication using the same plurality of links is assumed.

On the other hand, in an existing wireless LAN system, multi-user multiplex communication has been put into practical use. For example, there has been proposed a wireless LAN system that multiplexes and transmits more data by simultaneously transmitting and receiving a plurality of streams on one frequency channel. Specifically, any resource is allocated from an access point to each of a plurality of communication terminals and transmitted, and each communication terminal on the reception side can receive desired data by separating and decoding each resource. That is, in conventional downlink multi-user (DL MU) communication, even in a case where data is unilaterally multiplexed and transmitted from an access point, all communication terminals perform reception on the frequency channels (links), and data for each user can be obtained by separation on the basis of information described in header information of a received frame.

In IEEE 802.11ax, regarding resource allocation in multiplex communication, in a case of performing uplink and downlink multi-user multiplex communication, an access point (AP) performs notification of Bandwidth Query Report Poll (BQRP) Trigger Frame, communication terminals (STAs), in response to this, return Bandwidth Query Report (BQR) including available channel information in Bandwidth Query Report Control Subfield, and the AP performs resource allocation on the basis of the BQR from the STAs (see, for example, Non-Patent Document 1).

CITATION LIST

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

An object of the present disclosure is to provide a communication device and a communication method for performing wireless communication with a plurality of users using a plurality of frequency bands.

Solutions to Problems

The present disclosure has been made in view of the issue described above, and a first aspect thereof isa communication device includinga communication unit capable of wirelessly communicating on a plurality of links,a communication processing unit that performs processing of simultaneously transmitting data to a plurality of reception-side communication devices, anda control unit that performs control to transmit data using an optimum link to each of the plurality of reception-side communication devices.

The control unit performs control to transmit a trigger request signal for requesting information regarding a reception opportunity from the plurality of reception-side communication devices on a link on which a transmission opportunity has been acquired, and determine an optimum link for each reception-side communication device on the basis of a request response signal from the plurality of reception-side communication devices.

Furthermore, the control unit performs control to transmit an allocation signal including information regarding a link allocated to each reception-side communication device and information regarding multi-user multiplex communication.

Furthermore, the control unit controls simultaneous data transmission to the plurality of reception-side communication devices using the plurality of links on the basis of information regarding a link allocated to each reception-side communication device and information regarding multi-user multiplex communication.

Furthermore, a second aspect of the present disclosure isa communication method in a communication device capable of wirelessly communicating on a plurality of links, the method includinga step of determining an optimum link for each of the plurality of reception-side communication devices, anda step of simultaneously transmitting data to a plurality of reception-side communication devices using an optimum link of each reception-side communication device.

Furthermore, a third aspect of the present disclosure isa communication device including acommunication unit capable of wirelessly communicating on a plurality of links,a communication processing unit that performs processing of receiving data addressed to the communication device among data simultaneously transmitted from a transmission-side communication device to a plurality of reception-side communication devices, anda control unit that notifies the transmission-side communication device of a reception opportunity of a link available to the communication device, and performs control to receive data on a link designated by the transmission-side communication device.

The control unit performs control to return a request response signal on a link on which a reception opportunity can be acquired on an all link on which a reception opportunity has been able to be acquired in response to reception of a trigger request signal from the transmission-side communication device.

Furthermore, the control unit performs control to wait for reception of data addressed to a plurality of reception-side communication devices from the transmission-side communication device on a link on which the request response signal has been transmitted.

Furthermore, a fourth aspect of the present disclosure is a communication method in a communication device capable of wirelessly communicating on a plurality of links, the method includinga step of notifying a transmission-side communication device of information regarding a reception opportunity of a link available to the communication device, anda step of receiving data addressed to the communication device among data simultaneously transmitted from the transmission-side communication device to a plurality of reception-side communication devices on a link designated by the transmission-side communication device.

Effects of the Invention

According to the present disclosure, a communication device and a communication method for performing wireless communication with a plurality of users using a plurality of links can be provided.

Note that the effects described in the present specification are merely examples, and the effects brought by the present disclosure are not limited thereto. Furthermore, the present disclosure may further provide additional effects in addition to the effects described above.

Still another object, feature, and advantage of the present disclosure will become clear by further detailed description with reference to an embodiment to be described below and the attached drawings.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present disclosure will be described in the following order with reference to the drawings.A. OverviewB. Network ConfigurationC. Downlink Multi-User Multiplex Communication Applied to MLOD. Usage Detection Statuses of Multi-Links in AP and STAE. Implementation Example in Which Downlink Multi-User Communication is Applied to Multi-LinksF. Sequence of Downlink Multi-User MultiplexCommunication of Each LinkG. Configuration of Wireless Communication DeviceH. Frame ConfigurationI. Operation Example of Downlink CommunicationJ. Effects

From the viewpoint of securing compatibility with a conventional wireless LAN system, in a case where a transmission path is being used on one of a plurality of frequency bands (links), there are an issue that transmission using the frequency band (link) cannot be performed and an issue that timing at which transmission is possible differs for each of the frequency bands (links). Furthermore, random backoff needs to be set for each of the frequency bands (links), but there is also an issue that transmission is not simultaneously started on each of the frequency bands (links) depending on a set value of the random backoff even if the transmission path is in an empty state.

Moreover, even if a link is available in a certain communication device, the link may not be available in another communication device, and thus, there is also an issue that simultaneously transmitting data addressed to a plurality of communication devices is difficult. For example, in a case where an access point uses three links from a first link to a third link for multi-link operation, the first link and the second link may be available in a certain communication terminal connected to the access point, but the first link and the third link may be available in another communication terminal.

Regarding multi-link operation, as communication terminals that cannot simultaneously receive a plurality of links, devices that are Enhanced Single Radio also exist on a network. Therefore, a technology that does not contradict operation of these communication devices is required to be established.

In conventional downlink multi-user communication, all reception-side communication devices perform reception on the frequency channels (links). Here, in a case where another basic service set (BSS) that exists in an overlapping manner in the vicinity, that is, an overlapping basic service set (OBSS) exists, there is a high possibility that some reception-side communication devices of multi-link operation cannot correctly receive header information of a received frame.

However, in BQRP Trigger Frame standardized in IEEE 802.11ax, there is an issue that the setting to STAs is performed only for requesting return of BQR and notification of a detailed parameter cannot be performed.

Furthermore, there is an issue that, in BQR Control Subfield standardized in IEEE 802.11ax, only short information can be returned, and only about 8 pieces of available channel information can be continuously transmitted.

Moreover, channel availability determination is made on the basis of a detection result of clear channel assessment (CCA). For this reason, there is an issue that, even in a state where a network allocation vector (NAV) is set at the time of receiving a signal from an OBSS STA in advance, it is determined that a channel is available if a signal is not actually detected, and in a case where the channel is allocated from an access point, the NAV is actually set and transmission cannot be performed.

Issues in establishing multi-user communication in multi-link operation will be summarized.

First, there is an issue that, in a case where a communication device on the transmission side acquires a transmission right, links available to each of a plurality of communication devices on the reception side cannot be grasped at that time. That is, in a case where the communication device on the transmission side acquires a transmission opportunity (TXOP) on all links or a plurality of links and data transmission is performed without the usage statuses of these links in each of the communication devices on the reception side being grasped, the communication devices on the reception side cannot correctly receive the data.

Furthermore, since it is difficult for a device of Enhanced Single Radio to operate on a plurality of links, there is an issue that reception cannot be simultaneously performed on a plurality of links in multi-link operation. Therefore, in Enhanced Single Radio, an available link needs to be preferentially caused to be used.

Therefore, at the time of multi-link operation, each of a plurality of communication devices on the reception side that are multi-users notifies a communication device on the transmission side of information of a reception opportunity (RXOP) on an available link, and the communication device on the transmission side needs to determine to which link data addressed to the communication devices on the reception side is to be allocated and transmitted according to the RXOP status of each of the communication devices on the reception side.

Next, according to the present disclosure, a method in which communication devices on the reception side exchange RXOP information in a case of performing multi-user communication in multi-link operation, and a method in which an AP that is TXOP Holder grasps RXOP for each STA, determines availability for each STA, and performs control to appropriately allocate each link of multi-links will be described.

Downlink multi-user communication by multi-link operation (MLO) from an access point (AP) to a plurality of subordinate communication terminals (STAs) is performed by the following procedure.

(1) The AP transmits MU-MLO Trigger Request to each of the STAs on the reception side on a link on which transmission can be performed.

(2) Each of the STAs returns MU-MLO Request Response including RXOP information on multi-links to the AP.

(3) The AP sets a downlink resource to be used for reception for each of the STAs from the RXOP information received from each of the STAs on the reception side.

(4) If necessary (or optionally), the AP transmits MU-MLO Allocation to the STAs to notify the STAs of links to be used.

(5) The STAs perform waiting operation on all links on which the MU-MLO Request Response has been returned.

(6) Upon receiving the MU-MLO Allocation from the AP, the STAs receive data from the AP only on links allocated to the STAs.

(7) Upon returning Block ACK to the AP, the STAs continue to return Block ACK including RXOP information indicating the availability.

(8) Upon receiving the Block Ack returned from the STAs, the AP performs notification of retransmission of undelivered data by Allocation (optional).

(9) Even if there is no MU-MLO Request Response, the AP may transmit urgent data using a remaining link.

Furthermore, the AP may repeatedly perform downlink MLO including operation of (1) to (9) described above over time during which TXOP is obtained. In addition, in a case where reverse direction, that is, uplink data transmission is required, the AP may continue to allocate parameters for uplink multi-user communication, or may allocate new parameters.

B. Network Configuration

FIG.1illustrates states of networks of a wireless LAN system to which the present disclosure is applied. In the illustrated example, a plurality of communication terminals (STAs11to14) is connected to a Basic Service Set1(BBS1) that is a network operated by an access point (AP10).

Furthermore, another BBS (OBSS) exists in the neighborhood of the BBS1in an overlapping manner. In the example illustrated inFIG.1, there are an OBSS2operated by an AP20and an OBSS3operated by an AP30. Then, an STA21and an STA22are connected to the OBSS2, and an STA31and an STA32are connected to the OBSS3.

Note that, inFIG.1, radio wave coverage of each access point AP10, AP20, and AP30is indicated by an ellipse drawn using a dotted line, and this indicates the range of each network.

In the states of networks illustrated inFIG.1, the STA12can grasp a signal from the AP20of the BSS2, and the STA13can grasp a signal from the AP30of the BSS3. Therefore, in the BSS1, a network configuration is adopted in which interference is received or given from or to each other in a case where the same link as that of each adjacent OBSS is used.

In the present embodiment, for example, it is assumed that multi-link operation is performed in the BBS1. Furthermore, it is assumed that the multi-link operation is performed even in an environment in which an EMLMR device and an EMLSR device are mixed in the BBS1.

FIG.2illustrates an example of frequency bands and channel allocation used in the wireless LAN system to which the present disclosure is applied. In the drawing, an example of channel allocation on each of the frequency bands of a 2.4 GHz band, a 5 GHz band, and a 6 GHz band that available to the wireless LAN is illustrated. In each of the frequency bands, the horizontal axis is a frequency axis.

In the 2.4 GHz band, in a case of applying to a wireless signal of an orthogonal frequency division multiplexing (OFDM) method with a 20 MHz bandwidth in the IEEE 802.11g standard, frequencies for at least two channels are set.

Furthermore, in the 5 GHz band, a plurality of channels to be applied to a wireless signal of the OFDM method with the 20 MHz bandwidth can be secured for a standard of IEEE 802.11a and the like. However, operation in the 5 GHz band is provided with conditions for determining an available frequency range, transmission power, and transmission possibility by the legal systems of respective countries. In the 5 GHz band, channel numbers are assigned along the horizontal axis. In Japan, 8 channels from a channel 36 to a channel 64 and 11 channels from a channel 100 to a channel 140 can be used. Note that, in other countries and regions, a channel 32, a channel 68, a channel 96, and a channel 144 can also be used, and further, in the frequency band thereabove, channels 149 to 173 can be used.

Furthermore, standardization is currently in progress so that the 6 GHz band can also be used. According to the standard content, 25 channels can be arranged in the UNii-5 band of the 6 GHz band A, five channels can be arranged in the UNii-6 band of the 6 GHz band B, 17 channels can be arranged in the UNii-7 band of the 6 GHz band C, and 12 channels can be arranged in the UNii-8 band of the 6 GHz band D.

In the multi-link operation described in this specification, one link is formed by one or a combination of two or more channels in the channel configuration illustrated inFIG.2. Furthermore, one link may be formed by two or more channels that are continuous on the frequency axis, or one link may be formed by two or more channels that are not continuous on the frequency axis.

C. Downlink Multi-User Multiplex Communication Applied to MLO

FIG.3illustrates an example in which downlink multi-user multiplex communication (DL MU) is applied to the MLO.FIG.3illustrates data transmission and reception states viewed from the viewpoint of the AP in a case where downlink multi-user multiplex communication is performed on each link of links1to4in order from the top. Provided that the horizontal axes are assumed as the time axes, data transmission and reception states of the links1to4are illustrated. In each of the time axes, a state of upward protrusion represents a state in which the AP performs transmission operation on the corresponding link, and a state of downward protrusion represents a state in which the AP performs reception operation on the corresponding link.

The AP transmits Trigger Request (TR) to each of the STAs in which data that is a sending destination exists on all available links. In a case where all the links are available and TXOP has been able to be acquired, the AP transmits TR using the links1to4, but may transmit TR only on a link that has gotten available at that time.

On the other hand, each of the STAs that is on the reception side receives the TR from the AP on all the available links. The STAs return Request Response (RR) if the links on which the TR is received are available. The AP receives the RR from the STAs on each of the links.

Here, on a link on which a signal from an adjacent OBSS is detected or a link on which an NAV of the OBSS is set, the STAs do not return RR on the link so as not to interfere with communication of the OBSS. That is, the STAs that are on the reception side transmit RR including information indicating that RXOP in the links is obtained.

Note that the STAs may return RR on all available links as long as the devices are EMLMR devices. On the other hand, if the STAs are EMLSR devices, the STAs may return RR only on links on which the STAs perform reception operation. That is, resources for returning RR are allocated to STAs required to perform returning. For example, a plurality of STAs may return RR using a mechanism of uplink multi-user multiplex communication.

The AP can grasp available links capable of multi-user multiplex communication for each of the STAs according to the reception status of the RR returned from each of the STAs. Then, the AP transmits Allocation (AL) to each of the STAs to notify each of the STAs in advance of links to be used for downlink multiplex communication. Note that the AP may transmit data of later down multi-user multiplex communication using available links in notification by the STAs in RR without transmitting the AL.

Here, in a case where the STAs can receive the AL from the AP, the STAs receive data on links designated on the basis of the information. Furthermore, even if the STAs cannot receive the AL from the AP, the STAs may perform reception on the corresponding links and receive data of later multi-user multiplex communication.

In the example illustrated inFIG.3, the AP performs DL MU transmission of Downlink User Data1and Downlink User Data2on the link1, DL MU transmission of Downlink User Data3and Downlink User Data4on the link2, DL MU transmission of Downlink User Data5and Downlink User Data6on the link3, and DL MU transmission of Downlink User Data7and Downlink User Data8on the link4.

In this way, the AP can transmit data addressed to each of the STAs by downlink multi-user multiplex communication.

Moreover, each of the STAs that has received the data by the downlink multi-user multiplex communication returns Block ACK (BA) as necessary. At that time, the AP may designate in advance resources for returning BA using, for example, the mechanism of uplink multi-user multiplex communication, and the STAs may return BA using the resources. Furthermore, the STAs may return BA including RXOP information indicating that reception can be continuously performed thereafter on the links.

In a case where retransmission is necessary according to the reception statuses of the BA from the STAs, the AP may retransmit the data by later downlink multi-user multiplex communication.

Furthermore, in a case where there is a remaining time in the TXOP in each of the links, the AP may transmit AL to each of the STAs again, or may not transmit the AL. Then, the AP performs downlink multi-user communication continuously on each of the links. Moreover, each of the STAs may be formed to return BA after performing downlink multi-user communication.

In the example illustrated inFIG.3, the AP transmits AL to each of the STAs again, and then performs DL MU transmission of Downlink User Data9and Downlink User Data10on the link1, DL MU transmission of Downlink User Data11and Downlink User Data12on the link2, DL MU transmission of Downlink User Data13and Downlink User Data14on the link3, and DL MU transmission of Downlink User Data15and Downlink User Data16on the link4. Then, each of the STAs returns BA.

FIG.3illustrates an example in which such a series of operation is simultaneously performed on each of the links, but may be performed asynchronously in each of the links.

FIG.4illustrates a modification in which downlink multi-user multiplex communication (DL MU) is applied to the MLO. InFIG.4, in a case where the AP performs downlink multi-user multiplex communication, the STAs return Clear To Send: CTS (CS) and reliably perform communication. In this case, a state of data transmission and reception viewed from the viewpoint of each of devices (STAs) of EMLSR and EMLMR that are data transmission destinations is illustrated. Provided that the horizontal axes are assumed as the time axes, a state of upward protrusion on the same time axis represents a state in which the STAs of EMLSR and EMLMR perform transmission operation on a link N, and a state of downward protrusion represents a state in which the STAs of EMLSR and EMLMR perform reception operation on the link N.

The EMLSR STA is formed to return, upon receiving a TR signal from the AP, Clear to Send: CTS (CS) to clearly indicate that the EMLSR STA operates on the link instead of RR. In this case, the EMLSR STA can inform devices of an overlapping network (OBSS) that setting of an NAV is performed by clearly returning the CS. Moreover, for example, in a case where retransmission is necessary, the EMLSR STA can indicate an intention to continuously use the link by also sending a frame corresponding to the CS at the time of returning BA.

The example illustrated inFIG.4illustrates a state in which the EMLSR STA returns BA and CS following reception of Downlink Multi-User Data A from the AP on the link N designated by AL from the AP, and then returns BA following reception of Downlink Multi-User Data B from the AP. As a result, a method of, even if the AP operates in multi-link operation, effectively performing multi-user multiplex communication even in the EMLSR STA that can use a link in a limited manner can be obtained.

Similarly, the EMLMR STA is formed to return, upon receiving a TR signal from the AP, CS to clearly indicate that the EMLMR STA operates on the link instead of RR. In this case, since RXOP can be set on other links in a case of the EMLMR STA, a resource is not necessarily allocated on the link on which the CS has been returned. In a case where AL in which multi-user multiplex communication is performed is not received from the AP on the link, or in a case where communication of the EMLMR STA is not included in the AL, the EMLMR STA may transmit Contention Free End (CF-End) (CE) indicating that reception is ended.

Note that, also for CS from the EMLSR STA, in a case where AL in which multi-user multiplex communication is performed is not received from the AP on the link, or in a case where communication of the EMLSR STA is not included in the AL, the EMLSR STA may transmit a CE frame corresponding to CF-End indicating that reception is ended.

FIG.5illustrates another modification in which downlink multi-user multiplex communication (DL MU) is applied to the MLO.FIG.5illustrates a state of data transmission and reception from the viewpoint of an STA after the STA receives a TR signal from the AP on the link N. Provided that the horizontal axis is assumed as the time axis, a state of upward protrusion on the same time axis represents a state in which the STA performs transmission operation on the link N, and a state of downward protrusion represents a state in which the STA performs reception operation on the link N.

The STA returns Clear to Send: CTS (CS) on a link on which TR has been received from the AP, similarly to the above example illustrated inFIG.4. In the example illustrated inFIG.5, the STA returns BA following reception of the Downlink Multi-User Data A from the AP on the link N designated by AL from the AP.

Any STA can notify the devices of the OBSS that setting of an NAV is performed by transmitting CS after receiving AL on any link. Therefore, the STA can reliably receive downlink multi-user multiplex communication even if the STA is not an EMLSR STA.

FIG.6illustrates a modification in which uplink multi-user multiplex communication (UL MU) is performed after downlink multi-user multiplex communication (DL MU) to which the MLO is applied.FIG.6illustrates a state of data transmission and reception from the viewpoint of the AP after the AP transmits a TR signal on the link N. Provided that the horizontal axis is assumed as the time axis, a state of upward protrusion on the same time axis represents a state in which the AP performs transmission operation on the link N, and a state of downward protrusion represents a state in which the AP performs reception operation on the link N.

On a link on which TR has been transmitted, RR is returned from the transmission destination STA to the AP. Then, the AP transmits AL according to the reception status of the RR returned from each STA, and then can transmit data addressed to each STA by downlink multi-user multiplex communication (the same as above). In the example illustrated inFIG.6, the AP performs the Downlink User Data A and the Downlink User Data B as downlink multi-user multiplex communication for STAs on the link N. BA is returned from STAs that have received the data from the AP.

Thereafter, the AP allocates a resource for uplink multi-user multiplex communication on the link N and transmits AL on the link N. Then, transmission of Uplink User Data C and Uplink User Data D is performed on the link N as uplink multi-user multiplex communication (UL MU) from the STAs to the AP, and the AP receives the uplink multi-user multiplexed transmitted data. Note that the AP may return BA to the transmission source STAs after the uplink multi-user multiplex communication.

D. Usage Detection Statuses of Multi-Links in AP and STA

FIG.7illustrates an example of usage detection statuses of the multi-links in the AP10of the wireless LAN system illustrated inFIG.1. In the example illustrated inFIG.7, in a case where the AP10intends to perform the MLO using the links1to4, only the link2cannot be used since a signal from another network is detected, and is in a Busy state.

FIG.8illustrates an example of usage detection statuses of the multi-links in the STA11subordinate to the AP10. In the example illustrated inFIG.8, in a case where the STA11intends to perform the MLO using the links1to4, all the links can be used since a signal from another network is not detected.

FIG.9illustrates an example of usage detection statuses of the multi-links in the STA12subordinate to the AP10. In the example illustrated inFIG.9, in a case where the STA12intends to perform the MLO using the links1to4, the link1cannot be used since a signal from another network is detected intermittently, and is in a Busy state.

FIG.10illustrates an example of usage detection statuses of the multi-links in the STA13subordinate to the AP10. In the example illustrated inFIG.10, in a case where the STA13intends to perform the MLO using the links1to4, the links3and4cannot be used since a signal from another network is detected, and are in a Busy state. Specifically, the STA13first detects a signal from another network on the link3that then enters a Busy state, and thereafter, detects a signal from another network also on the link4that then enters a Busy state.

FIG.11illustrates an example of usage detection statuses of the multi-links in the STA14subordinate to the AP10. In the example illustrated inFIG.11, the STA14operates as an EMLSR device, and is in a state of setting RXOP of data using only the link1among the links1to4.

As illustrated inFIGS.7to11, a case where the AP and each of the STAs subordinate thereto each have different available links, in other words, a case where performing multi-link operation using all the links is difficult is assumed. Furthermore, a case where an EMLSR device is included in the STAs subordinate to the AP is assumed.

E. Implementation Example in Which Downlink Multi-User Communication is Applied to Multi-Links

FIG.12illustrates an implementation example in which downlink multi-user communication is applied to multi-links in the AP10of the wireless LAN system illustrated inFIG.1. Here, operation of the AP10is illustrated in which a case where downlink multi-user communication as illustrated inFIG.3is applied under the usage detection statuses of the multi-links illustrated inFIG.7is assumed. Provided that the horizontal axes are assumed as the time axes, data transmission and reception states of the links1to4are illustrated. In each of the time axes, a state of upward protrusion represents a state in which the AP10performs transmission operation on the corresponding link, and a state of downward protrusion represents a state in which the AP10performs reception operation on the corresponding link.

The AP10cannot perform DL MU communication since a signal from the OBSS is detected on the link2that then enters a Busy state. Therefore, the AP10transmits TR to the STAs11to14in which data that is a sending destination exists on links1,3, and4, and starts a series of operation of DL MU communication.

On the other hand, the STAs11to14that are on the reception side receive the TR from the AP10on the links1,3, and4. The STAs11to14return RR including RXOP information at that time to the AP10on the links1,3, and4.

The AP10can grasp links that are capable of multi-user multiplex communication and available to each of the STAs11to14according to the reception statuses of the RR returned from the STAs11to14. Then, the AP transmits AL to the STAs11to14on the links1,3, and4to notify the STAs11to14in advance of links to be used for DL MU.

Next, the AP10performs DL MU communication addressed to the STAs11to14on each of the links1,3, and4on the basis of the AL. Specifically, the AP10transmits the Downlink User Data1and the Downlink User Data2on the link1, transmits the Downlink User Data5and the Downlink User Data6on the link3, and transmits the Downlink User Data7and the Downlink User Data8on the link4.

Thereafter, in order to return BA from the STAs11to14, the AP10may allocate resources for returning the BA in advance using an uplink multi-user multiplex technique. The STAs11to14may return BA using the resources. As a result, the AP10can determine the presence or absence of undelivered data that needs to be retransmitted according to the reception statuses of the BA from the STAs11to14.

In a case where there is a remaining time in the TXOP in each of the links1,3, and4, the AP10can transmit AL to the STAs11to14again. In the example illustrated inFIG.12, the AP10performs DL MU communication addressed to the STAs11to14on each of the links1,3, and4on the basis of the AL. Specifically, the AP10transmits the Downlink User Data9and the Downlink User Data10on the link1, transmits the Downlink User Data13and the Downlink User Data14on the link3, and transmits the Downlink User Data15and the Downlink User Data16on the link4. Note that, in the example illustrated inFIG.12, data transmission is performed on all available links, but data transmission may be performed using only some of the links depending on the amount of the data.

Then, similarly to the above, in order to return BA from the STAs11to14, the AP10may allocate resources for returning the BA in advance using the uplink multi-user multiplex technique. The STAs11to14may return BA using the resources. The AP10can determine the presence or absence of undelivered data that needs to be retransmitted according to the reception statuses of the BA from the STAs11to14.

FIG.13illustrates an implementation example in which downlink multi-user communication is applied to the multi-links in the STA11subordinate to the AP10. Here, operation of the STA11is illustrated in which a case where downlink multi-user communication as illustrated inFIG.3is applied under the usage detection statuses of the multi-links illustrated in FIG.8is assumed. Provided that the horizontal axes are assumed as the time axes, data transmission and reception states of the links1to4are illustrated. In each of the time axes, a state of upward protrusion represents a state in which the STA11performs transmission operation on the corresponding link, and a state of downward protrusion represents a state in which the SAT11performs reception operation on the corresponding link.

Since the STA11has not detected a signal from the OBSS on all of the links1to4, the STA11receives TR from the AP10on the links1,3, and4, and starts a series of operation of DL MU communication.

Then, the STA11returns RR including RXOP information at that time to the AP10on the links1,3, and4. Since there is a possibility that DL MU communication is performed thereafter on the links1,3, and4on which the RR has been returned, the STA11waits for data from the AP10on all these links.

Thereafter, the STA11receives AL from the AP10on the links1,3, and4. In the example illustrated inFIG.13, since a resource for DL MU communication is allocated to the STA11by AL of the link3, the STA11receives data of DL MU communication addressed to the STA11(Downlink User Data6) on the link3.

Next, the STA11returns BA in which the data reception statuses are described to the AP10. The STA11returns BA on the link3on which the data has been received, but may return BA on another link as necessary. In the example illustrated inFIG.13, the STA11returns BA in each of the links1,3, and4.

In a case where the AP10has a remaining time in TXOP in each of the links1,3, and4, there is a possibility that DL MU communication is performed thereafter. Therefore, the STA11may be formed to wait for data on each of the links1,3, and4.

Then, in a case where the STA11receives AL from the AP10again on any of the links1,3, and4, the STA11confirms the description content of the AL and waits for data. In the example illustrated inFIG.13, since a resource for DL MU communication is allocated to the STA11by AL of the links3and4, the STA11receives data of DL MU communication addressed to the STA11(Downlink User Data14, Downlink User Data16) on the links3and4.

Then, the STA11returns BA in which the data reception statuses on the links3and4are described to the AP10on each link.

FIG.14illustrates an implementation example in which downlink multi-user communication is applied to the multi-links in the STA12subordinate to the AP10. Here, operation is illustrated in which a case where the STA12applies downlink multi-user communication as illustrated inFIG.3under the usage detection statuses of the multi-links illustrated inFIG.9is assumed.

Provided that the horizontal axes are assumed as the time axes, data transmission and reception states of the links1to4are illustrated. In each of the time axes, a state of upward protrusion represents a state in which the STA12performs transmission operation on the corresponding link, and a state of downward protrusion represents a state in which the STA12performs reception operation on the corresponding link.

Since the STA12has detected a signal from the OBSS on the link1, the STA12receives TR from the AP10on the links3and4, and starts a series of operation of DL MU communication. Then, the STA12returns RR including RXOP information at that time to the AP10on the links3and4. Since there is a possibility that DL MU communication is performed thereafter on the links3and4on which the RR has been returned, the STA12waits for data from the AP10on these links.

Thereafter, the STA12receives AL from the AP10on the links3and4. In the example illustrated inFIG.14, since a resource for DL MU communication is allocated to the STA12by AL of the links3and4, the STA12receives data of DL MU communication addressed to the STA12(Downlink User Data5) on the link3and receives data of DL MU communication addressed to the STA12(Downlink User Data8) on the link4.

Next, the STA12returns BA in which the data reception statuses are described to the AP10. The STA12returns BA on the links3and4on which the data has been received, but may return BA on another link as necessary.

In a case where the AP10has a remaining time in TXOP in each of the links3and4, there is a possibility that DL MU communication is performed thereafter. Therefore, the STA12may be formed to wait for data in each of the links3and4.

Then, in a case where the STA12receives AL from the AP10again in any of the links3and4, the STA12confirms the description content of the AL and waits for data. In the example illustrated inFIG.14, since a resource for DL MU communication is allocated to the STA12by AL of the links3and4, the STA12receives data of DL MU communication addressed to the STA12(Downlink User Data13, Downlink User Data15) on each of the links3and4.

Then, the STA12returns BA in which the data reception statuses on the links3and4are described to the AP10on each link.

FIG.15illustrates an implementation example in which downlink multi-user communication is applied to the multi-links in the STA13subordinate to the AP10. Here, operation is illustrated in which a case where the STA13applies downlink multi-user communication as illustrated inFIG.3under the usage detection statuses of the multi-links illustrated inFIG.10is assumed.

Provided that the horizontal axes are assumed as the time axes, data transmission and reception states of the links1to4are illustrated. In each of the time axes, a state of upward protrusion represents a state in which the STA13performs transmission operation on the corresponding link, and a state of downward protrusion represents a state in which the STA13performs reception operation on the corresponding link.

Since the STA13has detected a signal from the OBSS on the link3, the STA13receives TR from the AP10on links1and4, and starts a series of operation of DL MU communication. Then, the STA13returns RR including RXOP information at that time to the AP10on the links1and4. Since there is a possibility that DL MU communication is performed thereafter on the links1and4on which the RR has been returned, the STA13waits for data from the AP10on these links.

Thereafter, the STA13receives AL from the AP10on the links1and4. In the example illustrated inFIG.15, a resource for DL MU communication is allocated to the STA13by AL of the links1and4. Therefore, the STA13receives data of DL MU communication addressed to the STA13(Downlink User Data2) on the link1and receives data of DL MU communication addressed to the STA13(Downlink User Data7) on the link4.

However, the STA13detects a signal from the OBSS while receiving the Downlink User Data7on the link4, and some data is undelivered. Therefore, the STA13describes BA in which the data reception statuses on the links1and4are described in BA returned on the link1, and returns the BA to the AP10.

In a case where the AP10has a remaining time in TXOP in each of the links1and4, there is a possibility that retransmission of the undelivered data described above is performed thereafter as DL MU communication. Therefore, the STA13waits for data on all the links.

At this time, since the STA13has detected a signal from the OBSS on the links3and4, the STA13can receive AL from the AP10only on the link1. Then, upon confirming that a resource addressed to the STA13is allocated by the AL received again from the AP10on the link1, the STA13receives, as data of DL MU communication addressed to the STA13(Downlink User Data10) on the link1, for example, the undelivered data of the retransmitted Downlink User Data7.

Then, the STA13returns BA in which the data reception status on the link1is described to the AP10on the link1.

FIG.16illustrates an implementation example in which downlink multi-user communication is applied to the multi-links of an EMLSR device. Here, similarly to the example illustrated inFIG.11, operation is illustrated in which a case where the STA14subordinate to the AP10operates as an EMLSR device and is in a state of setting RXOP of data using only the link1among the links1to4, and downlink multi-user communication illustrated inFIG.3is applied is assumed. The drawing illustrates a state of data transmission of the link1using the horizontal axis as the time axis, and a state of upward protrusion represents a state in which the STA14performs transmission operation on the link1, and a state of downward protrusion represents a state in which the STA14performs reception operation on the link1.

Upon receiving TR from the AP10on the link1, the STA14returns RR including RXOP information at that time to the AP10on the link1. Since there is a possibility that DL MU communication is performed thereafter on the link1on which the RR has been returned, the STA14waits for data from the AP10on the link1.

Thereafter, the STA14receives AL from the AP10on the link1. In the example illustrated inFIG.16, a resource for DL MU communication is allocated to the STA14by AL of the link1. Therefore, the STA14receives data of DL MU communication addressed to the STA14(Downlink User Data1) on the link1. Then, the STA14returns BA in which the data reception status is described to the AP10on the link1.

Furthermore, in a case where the AP10has a remaining time in TXOP in the link1, there is a possibility that DL MU communication is performed thereafter. Therefore, the STA14waits for data on the link1.

Upon confirming that a resource addressed to the STA14is allocated by the AL received again from the AP on the link1, the STA14receives data of DL MU communication addressed to the STA14(Downlink User Data9) on the link1.

Then, the STA14returns BA in which the data reception status on the link1is described to the AP10on the link1.

F. Sequence of Downlink Multi-User Multiplex Communication of Each Link

In this item F, a sequence of downlink multi-user multiplex communication for each of the links in a case where the usage detection status of each of the links as illustrated inFIGS.7to11is assumed in the AP10of the wireless LAN system illustrated inFIG.1will be described.

FIG.17illustrates a sequence of downlink multi-user multiplex communication on the link1. In the illustrated sequence, control information and user data are exchanged between the AP10and the STAs11to14subordinate to the AP10.

First, DL MU MLO Trigger Request (TR) that triggers the start of the MLO to which DL MU communication is applied is transmitted from the AP10to the STAs11to14subordinate to the AP10.

Next, the STAs11,13, and14that have been able to receive the TR from the AP10return DL MU MLO Request Response (RR) in which RXOP information is described to the AP10.

Here, the AP10allocates resources of DL MU communication on the basis of the information of the RXOP of each of the STAs11,13, and14, and transmits AL (DL MU MLO Resource Allocation) to the STAs13and14to be multiplexed on the link1as necessary.

Then, the AP10transmits multiplexed data (DL User Data) to each of the STAs13and14on the link1. As illustrated inFIGS.15and16, the Downlink User Data2is transmitted to the STA13, and the Downlink User Data1is transmitted to the STA14.

Upon receiving the multiplexed data (DL User Data), the STAs13and14each return BA (DL MLO Block Ack) in which the reception status is described to the AP10on the link1.

FIG.18illustrates a sequence of downlink multi-user multiplex communication on the link4. In the illustrated sequence, control information and user data are exchanged between the AP10and the STAs11to14subordinate to the AP10.

First, DL MU MLO Trigger Request (TR) that triggers the start of the MLO to which DL MU communication is applied is transmitted from the AP10to the STAs11to14subordinate to the AP10.

Next, the STAs11to13that have been able to receive the TR from the AP10return DL MU MLO Request Response (RR) in which RXOP information is described to the AP10.

Here, the AP10allocates resources of DL MU communication to the STAs12and13on the basis of the information of the RXOP of each of the STAs11to13, and transmits AL (DL MU MLO Resource Allocation) to the STAs12and13to be multiplexed on the link4as necessary.

Then, the AP10transmits multiplexed data (DL User Data) to each of the STAs12and13on the link4.

Upon receiving the multiplexed data (DL User Data), the STAs12and13return BA in which the reception status is described to the AP10on the link4. As illustrated inFIGS.14and15, the Downlink User Data8is transmitted to the STA12, and the Downlink User Data7is transmitted to the STA13. However, the STA13detects a signal from the OBSS while receiving the Downlink User Data7, and some data is undelivered. Therefore, the STA13describes BA in which the data reception statuses on the links1and4are described in BA returned on the link1, and returns the BA to the AP10.

The STAs12and13each return BA (DL MLO Block Ack) in which the reception status of the multiplexed data (DL User Data) is described to the AP10on the link4. At this time, the STA13describes in the BA that some data has been undelivered.

G. Configuration of Wireless Communication Device

FIG.19schematically illustrates a functional configuration of a wireless communication device1900to which the present disclosure is applied. The illustrated wireless communication device1900can operate as an access point (AP) in the wireless LAN system illustrated inFIG.1, for example. Needless to say, the wireless communication device1900may operate as a communication terminal (STA) subordinately to any access point.

The illustrated communication device1900includes each functional module of a network connection module1901, an information input module1902, a device control module1903, an information output module1904, and a wireless communication module1905. Note that the communication device1900may further include other functional modules that are not illustrated, but the modules are not essential to implement the present disclosure and are not illustrated.

For example, in a case where the wireless communication device1900operates as an access point, the network connection module1901has a configuration in which a function as a communication modem or the like for connecting to a wide-area communication network such as the Internet is mounted. For example, the network connection module1901connects a public communication line and the Internet via an Internet service provider.

The information input module1902is a module for inputting information indicating an instruction from the user, and includes, for example, a push button, a keyboard, a touch panel, a mouse, and other input devices.

The device control module1903corresponds to a portion that performs control to operate a communication device intended by the user as an access point.

The information output module1904is a portion that specifically displays an operation state of the wireless communication device1900and information obtained via the network, includes, for example, a display element such as a light emitting diode (LED) display, a liquid crystal panel, or an organic electro-luminescence (EL) display, a speaker that outputs voice or music, and the like, and can display and notify the user of necessary information as necessary.

The wireless communication module1905is a functional module for processing wireless communication. The present disclosure is basically implemented by a function provided by the wireless communication module1905.

FIG.20illustrates an internal configuration of the wireless communication module1905that is one of the functional modules included in the wireless communication device1900illustrated inFIG.19, in detail. The illustrated wireless communication module1905includes an interface2001, a transmission buffer2002, a transmission sequence management unit2003, a transmission frame construction unit2004, a network management unit2005, a multi-link management unit2006, a multi-user multiplexing processing unit2007, a multi-link access control unit2008, a transmission unit2009, an antenna control unit2010, an antenna unit2011, a detection unit2012, a reception unit2013, a reception frame analysis unit2014, a reception sequence management unit2015, and a reception buffer2016.

The interface2001is connected to other modules (device control module1903and the like) in the wireless communication device1900, and exchanges various types of information and data.

The transmission buffer2002temporarily stores, for example, data received from other modules and to be transmitted wirelessly.

The transmission sequence management unit2003grasps data to be transmitted for each destination and manages the transmission sequence. The transmission frame construction unit2004constructs a transmission frame for each destination.

The network management unit2005manages each of information of an access point that belongs to a network of the wireless communication device1900(BSS) and information of a communication terminal. The multi-link management unit2006manages operation of the MLO.

The multi-user multiplexing processing unit2007performs processing for multi-user multiplex communication.

The multi-link access control unit2008controls transmission and reception on the basis of a predetermined access control procedure on each link of multi-links.

The transmission unit2009performs transmission processing of data to be transmitted. The transmission unit2009includes a plurality of (the number corresponding to the number of the multi-links of) transmission units A to D in order to individually transmit each link of the multi-links and user multiplexed data. Note that, inFIG.20, the four transmission units A to D are illustrated for convenience, but the number of transmission units may be three or less or five or more. However, in a case where the wireless communication device1900is an EMLSR device, the transmission unit2009may be only one transmission unit.

The antenna control unit2010controls the antenna unit2011that transmits and receives wireless signals. The antenna unit2011includes an antenna element that actually performs transmission and reception operation. As the antenna unit2011, the number of antennas A to D corresponding to the number of the multi-links is prepared as necessary, but may be three or less or five or more.

The detection unit2012detects a signal received by the antenna unit2011. The detection unit2012includes a plurality of (the number corresponding to the number of the multi-links of) detection units A to D. Note that, inFIG.20, the four detection units A to D are illustrated for convenience, but the number of detection units may be three or less or five or more. Provided that, even in a case where the wireless communication device1900is an EMLSR device, detection units corresponding to the number of the links are prepared.

The reception unit2013performs reception processing of data received via the antenna unit2011and the detection unit2012. The reception unit2013includes a plurality of (the number corresponding to the number of the multi-links of) reception units A to D in order to individually receive each link of the multi-links and user multiplexed data. Note that, inFIG.20, the four reception units A to D are illustrated for convenience, but the number of reception units may be three or less or five or more. However, in a case where the wireless communication device1900is an EMLSR device, the transmission unit2009may be only one reception unit.

The reception frame analysis unit2014decodes predetermined data from a signal received by each of the reception units A to D to construct reception data. The reception sequence management unit2015extracts a portion of data (payload) from a received frame and manages a received sequence. The reception buffer2016temporarily stores received data.

In a case where the wireless communication device1900operates as an access point, transmission processing of TR and AL is instructed by the multi-link management unit2006, and the TR and AL are each constructed as a transmission frame by the transmission frame construction unit2004.

Furthermore, in a case where the wireless communication device1900operates as an access point, RR and BA transmitted from communication terminals are each processed by each of the reception units A to D for each individual link and each individual user, and processed as received frames in the reception frame analysis unit2014.

On the other hand, in a case where the wireless communication device1900operates as a communication terminal and receives TR, the reception frame analysis unit2014recognizes the TR, the multi-link management unit2006collects information of RXOP, sets RR to be transmitted to the access point, and the transmission frame construction unit2004constructs an RR frame.

Furthermore, in a case where the wireless communication device1900operates as a communication terminal and receives AL from the access point of the connection destination, the reception frame analysis unit2014recognizes the AL, and the multi-link management unit2006instructs reception processing using a resource of DL MU communication allocated by the AL.

Furthermore, in a case where the wireless communication device1900operates as a communication terminal, a BA frame is constructed according to the reception status of data addressed to the wireless communication device1900in the reception sequence management unit2015, and the transmission frame construction unit2004constructs the BA frame.

H. Frame Configuration

In this item H, a configuration of a frame used in the wireless LAN system to which the present disclosure is applied will be described.

FIG.21illustrates a configuration of a management frame necessary for setting the MLO. The management frame here includes a DL Trigger Request (TR) frame, a DL Request Response (RR) frame, and a DL Allocation (AL) frame.

The frame illustrated inFIG.21includes, as a predetermined media access control (MAC) header, each field of Frame Control for identifying a type of the frame, Duration indicating duration of the frame, Receive Address for designating a reception-side device, and Transmit Address for designating a transmission-side device.

Furthermore, the frame illustrated inFIG.21includes a Multi-User Multi-Link Operation (MU MLO) information element (Information Element) as an MAC payload, and a frame check sequence (FCS) for data error detection is further added to the end of the frame.

As the MU MLO information element, Type indicating the format of the frame of the MU MLO, Length indicating the information length, and a parameter required for actual MLO operation are described. The configuration of the MU MLO information element is different for each management frame. Details of the configuration of the information element in each management frame will be described below.

FIG.22illustrates a correspondence relationship between values described in a Type field of the MU MLO information element and frame formats corresponding to the respective values. In the drawing,1: DL Trigger Request,2: DL Request Response,3: DL Allocation,5: UL Trigger Request,6: UL Request Response, and7: UL Allocation are defined.

FIG.23illustrates a configuration of an MU MLO Information Element field of the DL Trigger Request (TR) frame.

This information element is indicated as an MU MLO information element of the DL Trigger Request assuming Type=01. Moreover, this information element includes Multi-Link Information indicating parameters related to multi-link operation, Multi-User Information indicating parameters related to multi-user communication, TXOP Max. Duration indicating the maximum length of a transmission opportunity of downlink communication, TXOP Min. Duration similarly indicating the minimum necessary length, and other parameters added as necessary. On a communication terminal side that has received a TR frame, a remaining time of a transmission opportunity held by the transmission side can be estimated on the basis of information of the maximum length of the transmission opportunity described in the TXOP Max. Duration. Note that, in addition to this, any parameter Parameter may be described as necessary.

The Multi-Link Information field includes parameters of Multi-Link Counts indicating the number of the multi-links, Request Multi-Link Bitmap for identifying a channel of a requested multi-link in a bitmap format, 1st Link Info to Nth Link Info indicating information of first to Nth links, and the like.

Furthermore, the Multi-User Information field includes parameters of Multi-User Type indicating a multi-user multiplexing method, Number of Streams indicating the number of multiplexing per link, Request Streams indicating the number of request streams requested to be simultaneously received by a reception-side communication terminal, and the like.

FIG.24illustrates a configuration of an MU MLO Information Element field of the DL Request Response (RR) frame.

This information element is indicated as an MU MLO information element of the DL Request Response assuming Type=02. Moreover, this information element includes Multi-Link Information indicating parameters related to multi-link operation, Multi-User Information indicating parameters related to multi-user communication, RXOP Max. Duration indicating the maximum length of a reception opportunity of downlink communication, RXOP Min. Duration similarly indicating the minimum necessary length, and other parameters Parameter added as necessary.

The Multi-Link Information field includes parameters of Multi-Link Counts indicating the number of the multi-links, Available Multi-Link Bitmap for identifying a channel of an available multi-link in a bitmap format, 1st Link Info to Nth Link Info indicating information of first to Nth links, and the like.

Furthermore, the Multi-User Information field includes parameters of Multi-User Type indicating a multi-user multiplexing method, Number of Streams indicating the number of multiplexing per link, Available Streams indicating the number of available streams, and the like.

Furthermore, this information element includes information of EMLSR/EMLMR for identifying whether the communication terminal is EMLSR or EMLMR and the like as other parameters Parameter.

FIG.25illustrates a configuration of an MU MLO Information Element field of the DL Allocation (AL) frame.

This information element is indicated as an MU MLO information element of the DL Allocation assuming Type=03. Moreover, this information element includes parameters of Multi-Link Information indicating parameters related to multi-link operation, Multi-User Information indicating parameters related to multi-user communication, Current TXOP Duration indicating a transmission opportunity of downlink communication in the Allocation frame, Total TXOP Duration indicating a transmission opportunity in a case where usage is continuing, and, as other parameters added as necessary, ACK Policy indicating a method of returning ACK, After Allocation indicating later resource allocation, and the like. The ACK Policy parameter can be used for performing notification of allocation of a resource for receiving block ACK from the reception side.

The Multi-Link Information field includes parameters of Multi-Link Counts indicating the number of the multi-links, Allocate Multi-Link Bitmap for identifying a channel of an allocated multi-link in a bitmap format, Multi-Link Allocation corresponding to parameters of a bandwidth of a link on which the Allocation frame is transmitted and the like, and the like.

Furthermore, the Multi-User Information field includes parameters of Multi-User Allocation indicating a multi-user multiplexing method, Number of Streams indicating the number of multiplexing per link, 1st Used Info to Mth User Info indicating first to Mth user information, and the like. Each piece of user information includes parameters of Resource indicating an allocated resource, a parameter of Device for identifying a device and the like.

FIG.26illustrates a configuration of a downlink Block Acknowledgement (BA) frame. The BA frame has a configuration in which information corresponding to a conventional BA frame is described, includes each field of BA Control and BA Information subsequent to a predetermined MAC header (same as above), and FCS for error detection is added at the end.

The BA Control field includes each parameter of BA Ack Policy, BA Type, MLO Control, and TID_INFO. The BA Type indicates a format of the BA frame.FIG.26also illustrates a correspondence relationship between values described in the BA Type field and BA frame formats corresponding to the respective values. In the present embodiment,12: MU MLO is defined as a new BA Type.

Furthermore, in the present embodiment, an MLO Control parameter is described in a bit portion that has been conventionally Reserved in the BA Control field as necessary. The MLO Control includes parameters of More Data indicating that more data is required, TXOP/RXOP for identifying whether TXOP or RXOP can be set, Multi-Link Counts indicating the number of links capable of multi-link operation, Available Link Bitmap indicating available links in a bitmap format, and the like.

I. Operation Example of Downlink Communication

In this item I, operation performed by an access point and a communication terminal during downlink communication in the wireless LAN system to which the present disclosure is applied will be described.

FIGS.27and28illustrate operation performed by an access point during downlink communication in the form of flowcharts. Here, an operation sequence of activating downlink multi-user multiplex communication according to the present disclosure by transmitting a trigger from the access point as a part of the MLO is illustrated in the form of flowcharts.

First, upon receiving transmission data from the upper layer of the communication protocol (Yes in step S2701), the access point stores the data in the transmission buffer2002(step S2702), and acquires the address of the reception-side communication device (step S2703).

Then, in a case where downlink multi-user communication is performed in multi-links (Yes in step S2704), the access point sets multi-user and multi-link parameters (step S2705), and performs access control on each link that performs multi-link operation (step S2706).

Here, in a case where there is a link available for transmission (Yes in step S2707), the access point transmits a trigger request (Trigger Request: TR) frame on the link (step S2708). Then, in a case where a response (Request Response: RR) frame has been able to be received from a communication terminal (STA) on the link (Yes in step S2709), the access point sequentially stores the STA that has responded and the response parameter together with corresponding link information (step S2710).

Then, returning to step S2707, the access point transmits the TR frame on all links available for transmission.

Thereafter, upon ending reception of the RR frame on all the links available for transmission (No in step S2707), the access point acquires information from an STA that has responded on each of the links (step S2711). Here, in a case where the STA that has responded is a device having large restriction on available links or available resources like an EMLSR device (Yes in step S2712), the access point preferentially allocates a response link to the device (step S2714). Furthermore, in a case where the device is not a device device having large restriction on available links or available resources like EMLSR (No in step S2712) but the response is from an STA in which undelivered data exists (Yes in step S2713), the access point preferentially allocates a response link to the device (step S2714). Then, in a case where the response is from an STA other than that, the access point appropriately allocates a remaining resource (step S2715). In steps S2714and S2715, the access point sets parameters related to multi-link operation on the basis of the allocated resources, and also sets parameters related to multi-user communication.

Upon completing resource allocation for all STAs that have responded to the TR frame (Yes in step S2716), in a case where there is a remainder in the resources (Yes in step S2717), the access point may allocate a resource redundantly for data for which high reliability communication is required as necessary (step S2718).

Then, the access point generates an AL frame in which the parameters related to multi-link operation set in step S2714or S2715and the parameters related to multi-user communication are described, and transmits the AL frame on available links (step S2719). Subsequently, the access point acquires the data stored in the transmission buffer2002in step S2702(step S2720) and performs downlink multi-user communication on each of the links according to the resource allocation described above (step S2721).

Thereafter, the access point receives a BA frame from each of the STA that are reception destinations using resources allocated by the ACK Policy parameter of the AL frame (step S2722). Then, the access point checks whether there is undelivered data on the basis of the reception confirmation status of the BA frame from each of the STAs (step S2723).

In a case where there is no undelivered data (Yes in step S2723), the access point ends this processing.

On the other hand, in a case where there is undelivered data (No in step S2723), the access point checks whether there is a remaining time of the TXOP (S2724).

In a case where there is a remaining time of the TXOP (Yes in S2724), if the access point continuously needs to perform downlink multi-user multiplex communication, the access point can return to step S2705and perform downlink multi-user multiplex communication on each of the links again. Furthermore, in a case where there is no remaining time of the TXOP (No in step S2724), the access point temporarily ends the present processing.

FIGS.29and30illustrate operation performed by a communication terminal during downlink communication in the form of flowcharts. Here, an operation sequence of activating downlink multi-user multiplex communication according to the present disclosure by the communication terminal receiving a trigger from the access point as a part of the MLO is illustrated in the form of flowcharts.

First, the communication terminal performs reception operation on an operation link of multi-link operation (step S2901). The communication terminal may be formed such that detection operation of a predetermined preamble signal is performed in the multi-links even in a case of a device having large restriction on available links or available resources like an EMLSR device.

Here, in a case where a signal addressed to the OBSS or another communication device is received (Yes in step S2902), the communication terminal sets a BUSY state on the link (step S2903). Alternatively, in step S2903, in a case where the communication terminal receives a Request to Send (RTS) or Clear to Send (CTS) frame, or the like, the communication terminal may set a network allocation vector (NAV) for virtual carrier sense according to time information of Duration described therein or the like.

On the other hand, in a case where a trigger request frame for downlink multi-user multiplex communication is received from the access point of the connection destination (Yes in step S2904), the communication terminal acquires parameters for the MLO in DL MO communication from the received frame (S2905), and then, in a case where RXOP can be set in the corresponding link (S2906), the communication terminal sets a reception parameter (step S2907). However, in a case where the NAV is set in the corresponding link, the communication terminal does not set the RXOP in the link.

Next, the communication terminal checks whether the communication terminal is a device having large restriction on available links or available resources like an EMLSR device (step S2908). Then, in a case where the communication terminal is a device having large restriction on available links or available resources like an EMLSR device, and further identifies a link to be used, a CTS frame may be transmitted to the access point as necessary (step S2910). Furthermore, in a case where the communication terminal is not a device having large restriction on available links or available resources like an EMLSR device, or in other cases, the communication terminal transmits an RR frame (step S2909).

Then, the communication terminal waits for data of downlink multi-user communication on the link on which the CTS frame or the RR frame has been transmitted (step S2911).

Here, in a case where an AL frame is received from the access point of the connection destination (step S2712), the communication terminal receives data of later downlink multi-user communication according to the setting (step S2713).

Next, the communication terminal checks whether the data (MAC Protocol Data Unit: MPDU) has been able to be normally received by the MLO in the DL MU communication (step S2914). In a case where the data has been able to be normally received (Yes in step S2914), the access point stores the reception data in the reception buffer2016(step S2915), and stores a received sequence number as ACK information (S2916). Note that in a case where there is an error in the reception data, the reception data is not stored, and the sequence number is not stored as ACK information.

Moreover, in a case where return of a BA frame is requested after all the data is received (Yes in S2917), the communication terminal acquires the ACK information collected in the preceding step S2916(step S2918). Then, in a case where the communication terminal can continue the TXOP of the access point and can set the RXOP in the link (step S2919), such as a case where a signal from the OBSS is not detected or a case where there is no error in the data, the communication terminal continues to set a parameter of a response (Request Response) (S2920).

Then, for example, the communication terminal acquires a parameter of a resource for BA return set continuously to the DL MU communication (S2921), and then the communication terminal transmits a BA frame using a resource designated by an ACK Policy parameter of an AL frame (step S2922).

Then, in a case where reception of all the data addressed to the communication terminal is completed (Yes in step S2923), the communication terminal ends the present processing. Furthermore, in a case where return of a BA frame is not requested (No in S2917) or in a case where reception of all the data addressed to the communication device is not completed (No in step S2923), the processing returns to S2902and the above-described operation is repeatedly performed.

InFIGS.29and30, the operation is described as closed operation by one link, but in a case where the communication terminal performs reception of multi-user communication using a plurality of links, the reception processing may be performed temporally simultaneously on each of the links. In the determination in step S2912, operation of repeating the processing each time a frame is received on each of the links is described.

In this item J, effects brought about by the present disclosure are summarized.

(1) A transmission-side communication device receives reception opportunity (RXOP) information from reception-side communication devices on links on which transmission opportunities (TXOP) have been obtained, so that a link available in multi-links can be identified for each of the reception-side communication devices.

(2) In an environment where an OBSS exists, even in a case where the multi-links are unavailable in all the reception-side communication devices, the transmission-side communication device can perform multi-user communication using links available to the reception-side communication devices each time.

(3) A reception-side communication device that is EMLSR can also return RXOP information to the transmission-side communication device on a link on which reception is currently performed. Therefore, the transmission-side communication device can grasp which link the reception-side communication device that is EMLSR can use to perform communication.

(4) By a communication sequence in which the transmission-side communication device transmits a Trigger Request frame and the reception-side communication devices return Request Response, the transmission-side communication device can identify available links at that time.

(5) The transmission-side communication device can allocate an optimum link to each of the reception-side communication devices on the basis of the reception statuses of Request Response returned from the reception-side communication devices, and can efficiently use multi-links for which transmission opportunities are obtained.

(6) The reception-side communication devices return Block ACK frames as necessary, so that the transmission-side communication device can grasp whether retransmission is necessary. Furthermore, in a case where the transmission-side communication device can continue to use transmission paths, the transmission-side communication device can continuously perform transmission by the reception-side communication devices returning responses in which RXOP information is described.

(7) In short, the transmission-side communication device not only transmits data to one communication terminal on each of the links, but also can obtain a method of performing data communication using a link on which the communication terminal can perform reception using the technology of multi-user multiplex communication, so that transmission paths can be efficiently used by multi-user communication being applied to the MLO.

INDUSTRIAL APPLICABILITY

The present disclosure is heretofore described in detail with reference to the specific embodiment. However, it is obvious that those skilled in the art can make modifications and substitutions of the embodiment without departing from the gist of the present disclosure.

The present disclosure is applied to, for example, a network environment in which using all channels is difficult in multi-link operation, and each communication terminal notifies an access point of a multi-link in which a reception opportunity can be set, and the access point allocates a link on which data is transmitted to each communication terminal on the basis of information in the notification, thereby implementing downlink multi-user multiplex communication applied to the multi-link operation. Furthermore, according to the present disclosure, since the access point sets a reception opportunity of downlink multiplex communication to each subordinate communication terminal and performs data transmission, a resource of a link on which a communication terminal that is EMLSR is operating is also effectively allocated to the communication terminal. That is, according to the present disclosure, throughput in the entire network can be improved by application to a network environment in which multi-link operation using all channels is difficult.

Needless to say, the present disclosure is also applied to a network in which multi-link operation using all channels is easy, and the access point efficiently allocates a resource of a link on which data is transmitted to each communication terminal according to the amount of data to be transmitted and the like, thereby improving the throughput in the entire network.

Furthermore, in the present specification, the embodiment in which the present disclosure is applied to a wireless LAN system based on the IEEE 802.11 standard has been mainly described, but the application range of the present disclosure is not limited to a specific wireless standard, and the present disclosure can be similarly applied to various types of wireless networks.

In short, the present disclosure is heretofore described in a form of an example and the content described in this specification should not be interpreted in a limited manner. In order to determine the gist of the present disclosure, the claims should be taken into consideration.

Note that the present disclosure can have the following configurations.

(1) A communication device includinga communication unit capable of wirelessly communicating on a plurality of links,a communication processing unit that performs processing of simultaneously transmitting data to a plurality of reception-side communication devices, anda control unit that performs control to transmit data using an optimum link to each of the plurality of reception-side communication devices.

(2) The communication device according to (1) described above,in which the control unit performs control to transmit a trigger request signal for requesting information regarding a reception opportunity from the plurality of reception-side communication devices on a link on which a transmission opportunity has been acquired.

(3) The communication device according to (2) described above,in which the control unit performs control to receive a request response signal for responding to the trigger request signal.

(4) The communication device according to (3) described above,in which the control unit determines an optimum link for each reception-side communication device on the basis of a request response signal from the plurality of reception-side communication devices.

(5) The communication device according to (4) described above,in which the control unit determines an optimum link for each reception-side communication device with a request response signal received from a reception-side communication device having large restriction on a communication resource prioritized.

(6) The communication device according to any one of (1) to (5) described above,in which the control unit performs control to transmit an allocation signal including information regarding a link allocated to each reception-side communication device and information regarding multi-user multiplex communication.

(7) The communication device according to (4) described above,in which the control unit controls simultaneous data transmission to the plurality of reception-side communication devices using the plurality of links on the basis of information regarding a link allocated to each reception-side communication device and information regarding multi-user multiplex communication.

(8) The communication device according to any one of (1) to (7) described above,in which the control unit performs control to allocate a resource for receiving block ACK from the plurality of reception-side communication devices.

(9) The communication device according to (6) or (7) described above,in which the control unit repeatedly transmits the allocation signal in a case where there is a remaining time of the transmission opportunity.

(10) A communication method in a communication device capable of wirelessly communicating on a plurality of links, the method includinga step of determining an optimum link for each of the plurality of reception-side communication devices, anda step of simultaneously transmitting data to a plurality of reception-side communication devices using an optimum link of each reception-side communication device.

(11) A communication device includinga communication unit capable of wirelessly communicating on a plurality of links,a communication processing unit that performs processing of receiving data addressed to the communication device among data simultaneously transmitted from a transmission-side communication device to a plurality of reception-side communication devices, anda control unit that notifies the transmission-side communication device of a reception opportunity of a link available to the communication device, and performs control to receive data on a link designated by the transmission-side communication device.

(12) The communication device according to (11) described above,in which the control unit performs control to return a request response signal on a link on which a reception opportunity can be acquired in response to reception of a trigger request signal from the transmission-side communication device.

(13) The communication device according to (12) described above,in which the control unit performs control to return a request response signal on an all link on which a reception opportunity has been able to be acquired.

(14) The communication device according to any one of (11) to (13) described above,in which the control unit performs control to transmit a Clear to Send signal on a link on which reception is performed in a case where the communication unit or the communication processing unit has large restriction on a communication resource.

(15) The communication device according to (12) or (13) described above,in which the control unit performs control to wait for reception of data addressed to a plurality of reception-side communication devices from the transmission-side communication device on a link on which the request response signal has been transmitted.

(15-1) The communication device according to any one of (12) to (14) described above,in which the control unit performs control to wait for reception of data addressed to a plurality of reception-side communication devices from the transmission-side communication device on a link designated by an allocation signal received from the transmission-side communication device.

(16) The communication device according to any one of (11) to (15) described above,in which the control unit performs control to return block ACK to the transmission-side communication device.

(17) The communication device according to (16) described above,in which the control unit performs control to transmit the block ACK using a resource allocated from the transmission-side communication device.

(18) The communication device according to (16) or (17) described above,in which the control unit performs control to perform signal waiting processing in a case where data retransmission from the transmission-side communication device is necessary.

(19) The communication device according to any one of (11) to (18) described above,in which the control unit returns information regarding a reception opportunity of the communication device in a case where there is a remaining time of a transmission opportunity of the transmission-side communication device.

(20) A communication method in a communication device capable of wirelessly communicating on a plurality of links, the method includinga step of notifying a transmission-side communication device of information regarding a reception opportunity of a link available to the communication device, anda step of receiving data addressed to the communication device among data simultaneously transmitted from the transmission-side communication device to a plurality of reception-side communication devices on a link designated by the transmission-side communication device.

REFERENCE SIGNS LIST