Multilink operation with triggered frame alignment

Abstract

The present application relates to multi-link operation with triggered frame alignment. A multi-link device may be configured to initiate transmission of a first data unit on a first wireless link of a first multi-link device and request a trigger to be transmitted from a second multi-link device on a second wireless link. In response to receiving the trigger, the multi-link device may align a last symbol end time of a response transmission on the second wireless link with a last symbol end time of the first data unit being transmitted on the first multi-link device.

Description

[0001] Cross reference to application

[0002] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 62 / 952,127, filed on December 20, 2020, which is incorporated herein by reference in its entirety for all purposes. Technical Field

[0003] The present description relates generally to wireless communication systems, and more particularly to wireless local area network communications. Background Art

[0004] Wireless local area network (WLAN) devices communicate with each other over wireless links. WLAN devices may have multiple radio devices and media access control functions (MAC) built in to operate over multiple wireless links. Some devices may have interference coupling generated between wireless links that occurs during transmission. Simultaneous transmission and reception operations over these multiple wireless links may result in a decrease in system throughput and overall performance. Summary of the invention

[0005] In various aspects of the present disclosure, a method is provided, the method comprising: initiating transmission of a first data unit on a first wireless link of a first multi-link device; requesting, on the first wireless link, with a trigger request frame, transmission of a trigger from a second multi-link device on either or both of the first wireless link and a second wireless link, or on neither the first wireless link nor the second wireless link; and aligning a last symbol end time of a response transmission on the second wireless link with a last symbol end time of a response transmission on the first wireless link in response to receiving the trigger on both links.

[0006] In aspects of the present disclosure, a method is provided, the method comprising: receiving a first data unit on a first wireless link of a first multi-link device; receiving a second data unit on a second wireless link of the first multi-link device; determining an end time of the first data unit and an end time of the second data unit; and aligning an end time of a first response data unit on the first wireless link with an end time of a second response data unit on the second wireless link if the end time of the first data unit matches the end time of the second data unit.

[0007] In aspects of the present disclosure, a method is provided that includes indicating, by an associated access point multi-link device, requesting synchronization alignment within a basic service set.

[0008] In aspects of the disclosure, a method is provided that includes indicating, by a first multi-link device, media state information of a second wireless link within a frame transmitted over a first wireless link to a second multi-link device.

[0009] In aspects of the present disclosure, a method is provided, the method comprising: determining reception of a first data unit on a first wireless link of a first multi-link device; and communicating, by the first multi-link device to a second multi-link device on a second wireless link, a trigger causing transmission of a response frame with its end time aligned with an end time of the reception on the first wireless link.

[0010] In various aspects of the present disclosure, a method is provided, the method comprising: determining, by a first device, a future time at which frame exchange will not be possible; and transmitting a response frame indicating the future time at which frame exchange will not be possible in response to receiving a send request or an MU send request or a request for a trigger transmitted by a second device.

[0011] In aspects of the present disclosure, a method is provided, the method comprising: receiving, at a first multi-link device, on a first wireless link one or more frames providing future channel occupancy information for the link; initiating a first transmission by the first multi-link device on a second wireless link during a period of future channel occupancy of the first wireless link; and initiating a second transmission by the first multi-link device on the first wireless link a short amount of time after expiration of the future channel occupancy indication on the first wireless link, provided that the first transmission is still in progress at the time.

[0012] In aspects of the present disclosure, a method is provided, the method comprising: responding to a received send request transmitted by a first multi-link device with a send clear containing a duration field value indicating a time value that will cause physical layer protocol data units transmitted after the send clear to be aligned with physical layer protocol data units being received on another link. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Certain features of the inventive technology are set forth in the appended claims. However, for purposes of illustration, several embodiments of the inventive technology are set forth in the following drawings.

[0014] Figure 1 An example wireless communication environment is shown in which aspects of the present technology may be implemented.

[0015] Figure 2 is a block diagram illustrating components of an electronic system that may be used to implement aspects of the present technology.

[0016] Figure 3 is a schematic diagram illustrating a request to send (RTS) triggering sequence according to aspects of the present disclosure.

[0017] Figure 4 is a schematic diagram illustrating a delayed triggering sequence according to aspects of the present disclosure.

[0018] Figure 5 is a schematic diagram illustrating a short physical layer protocol data unit triggering sequence according to aspects of the present disclosure.

[0019] Figure 6 is a schematic diagram illustrating an enhanced distributed channel access sequence according to aspects of the present disclosure.

[0020] Figure 7 is a schematic diagram illustrating a synchronized transmitter enhanced distributed channel access sequence according to aspects of the present disclosure.

[0021] Figure 8 is a schematic diagram illustrating the content of a frame carrying cross-link information according to aspects of the present disclosure.

[0022] Fig. 9 is a schematic diagram illustrating a basic TX RX case according to aspects of the present disclosure.

[0023] Fig.10 is a schematic diagram illustrating an advanced TX RX case according to aspects of the present disclosure.

[0024] Fig.11 is a schematic diagram illustrating a UTA TX TX trigger case according to aspects of the present disclosure.

[0025] Fig.12 is a schematic diagram illustrating a TX TX RTS triggering case according to aspects of the present disclosure.

[0026] Fig.13 is a schematic diagram illustrating another TX TX RTS triggering case according to aspects of the present disclosure.

[0027] Fig.14 is a schematic diagram illustrating a UTA TX TX trigger swap case according to aspects of the present disclosure.

[0028] Fig.15 is a schematic diagram illustrating a TX TX priority access case according to aspects of the present disclosure.

[0029] Fig.16 is a schematic diagram showing an example of an RX operation with a reception scheme according to aspects of the present disclosure.

[0030] Fig.17 is a schematic diagram illustrating an uncorrelated transmit alignment case according to aspects of the present disclosure.

[0031] Fig.18 is a schematic diagram showing a UTA RX RX with a T case according to aspects of the present disclosure.

[0032] Fig.19FIG. 2 is a schematic diagram showing an example of RX operation with two reception schemes according to aspects of the present disclosure.

[0033] Fig. 20 is a schematic diagram illustrating a UTA RX TX uncorrelated case according to aspects of the present disclosure.

[0034] Fig.21 is a schematic diagram illustrating a UTA RX TX related case according to aspects of the present disclosure.

[0035] Fig. 22 is a schematic diagram illustrating a UTA TX RX unrelated case according to aspects of the present disclosure.

[0036] Fig.23 is a schematic diagram illustrating another UTA TX RX unrelated case according to aspects of the present disclosure.

[0037] Fig.24 is a schematic diagram illustrating a UTA TX RX related case according to aspects of the present disclosure.

[0038] Fig.25 is a schematic diagram illustrating a case where a UTA with a T MU DL uses a CTA according to aspects of the present disclosure.

[0039] Fig.26 is a schematic diagram illustrating a case where an AP needs to align transmission according to aspects of the present disclosure.

[0040] Fig. 27 is a schematic diagram showing an example of a SYT indication in a PHY header according to aspects of the present disclosure.

[0041] Fig.28 is a schematic diagram showing a case where the SYT is indicated in the MAC header according to aspects of the present disclosure.

[0042] Fig.29 is a schematic diagram illustrating a trigger request case according to aspects of the present disclosure.

[0043] Fig.30 is a schematic diagram illustrating another TX TX RTS triggering case according to aspects of the present disclosure.

[0044] Fig.31 is a schematic diagram illustrating a non-AP STA triggering sequence according to aspects of the present disclosure.

[0045] Fig.32 is a schematic diagram illustrating expected interference triggering cases according to aspects of the present disclosure. DETAILED DESCRIPTION

[0046] The detailed description set forth below is intended as a description of various configurations of the present invention technology, and is not intended to represent the only configuration in which the present invention technology can be practiced. The accompanying drawings are incorporated herein and constitute a part of the detailed description, which includes specific details that provide a thorough understanding of the present invention technology. However, the present invention technology is not limited to the specific details set forth herein, and can be practiced without one or more of the specific details. In some cases, structures and components are shown in block diagram form to avoid confusing the concepts of the present invention technology.

[0047] WLAN devices may have multiple radios and MACs built in to operate on multiple wireless links simultaneously. However, when there is a transmission occurring on one link, near-end crosstalk may cause deafness on another link, which may cause the reliability of the determination of the media state on the link to be significantly reduced. If the media state is incorrectly determined or cannot be determined, resulting in the loss of the correct media state, the transmitter may be out of MAC media state synchronization with other competing WLAN devices on the link, all of which use the media state of the link to determine when they can be allowed to access the media. When MAC media state synchronization fails, the media access mechanism fails and system throughput and performance may be reduced.

[0048] The present technology proposes a solution for ensuring that media state is not lost on a deaf link by forcing the transmissions on different links to align. The deafness on a link is temporary and can be directly related to the transmission on another link. According to aspects of the present technology, when the deafness disappears, the media state condition can be correctly confirmed within a relatively short period of time, thereby maintaining overall system MAC synchronization and system throughput.

[0049] According to aspects of the present technology, a first multi-link device may be configured to initiate transmission of a first data unit on a first wireless link of the first multi-link device and request a trigger from a second multi-link device to be transmitted on one or more of the first and second wireless links. In response to receiving the trigger, the multi-link device may align a last symbol end time of a response transmission on the second wireless link with a last symbol end time of a first data unit being transmitted on the first multi-link device.

[0050] According to aspects of the present technology, a first multi-link device may be configured to receive a first data unit on a first wireless link of the first multi-link device and receive a second data unit on a second wireless link of the first multi-link device. The first multi-link device may determine an end time of the first data unit and an end time of the second data unit. If the end time of the first data unit matches the end time of the second data unit, the first multi-link device may align an end time of a first response data unit on the first wireless link with an end time of a second response data unit on the second wireless link.

[0051] According to aspects of the present technology, a first multi-link device may be configured to initiate transmission of a first data unit on a first wireless link of the first multi-link device, and determine that transmission of a second data unit on a second wireless link of the first multi-link device is in progress. The first multi-link device may be configured to align an end of a last symbol of the first data unit transmitted on the first wireless link with an end of a last symbol of the second data unit transmitted on the second wireless link.

[0052] According to aspects of the present technology, a first multi-link device may be configured to initiate transmission of a first data unit on a first wireless link of the first multi-link device, and determine that transmission of a second data unit on a second wireless link of the first multi-link device is in progress. The first multi-link device may be configured to trigger alignment of a response data unit to the first data unit on the first wireless link with a response to the second data unit on the second wireless link.

[0053] Figure 1 An example wireless communication environment in which aspects of the present invention described herein and in the appendix are implemented is shown. In a wireless communication network 100 such as a wireless WLAN, a basic service set (BSS) includes multiple wireless communication devices (e.g., WLAN devices). In one aspect, a BSS refers to a set of sites (STAs) that can communicate synchronously, rather than a concept indicating a specific area. In this example, the wireless communication network 100 includes wireless communication devices 111-115, which may be referred to as STAs. Each of the wireless communication devices 111-115 includes a radio frequency (RF) transmitter and an RF receiver. The RF transmitter converts symbols into RF signals and transmits the RF signals via an antenna. The RF receiver receives the RF signals via an antenna and converts the RF signals into one or more symbols for processing.

[0054] Each of the wireless communication devices 111-115 may include a MAC layer and a physical (PHY) layer in accordance with the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard or other wireless communication standards (including draft revision IEEE 802.11ax). In this example, at least one wireless communication device (e.g., device 111) is an access point (AP). An AP may be referred to as an AP STA or an AP device. Other wireless communication devices (e.g., devices 112-115) may be non-AP STAs. Alternatively, all wireless communication devices 111-115 may be non-AP STAs in a dedicated networking environment.

[0055] AP STA and non-AP STA may be collectively referred to as STA. However, for simplicity of description, in some aspects, only non-AP STA may be referred to as STA. AP may be, for example, a centralized controller, a base station (BS), a node-B, a base transceiver system (BTS), a site controller, a network adapter, a network interface card (NIC), a router, etc. Non-AP STA (e.g., a client device that can be operated by a user) may be, for example, a device with wireless communication capabilities, a terminal, a wireless transmit / receive unit (WTRU), a user equipment (UE), a mobile station (MS), a mobile terminal, a mobile subscriber unit, a laptop computer, a non-mobile computing device (e.g., a desktop computer with wireless communication capabilities), etc. In one or more aspects, a non-AP STA may act as an AP (e.g., a wireless hotspot).

[0056] In one aspect, an AP is a functional entity for providing associated STAs with access to a distribution system via a wireless medium. For example, an AP may provide access to the Internet for one or more STAs that are wirelessly and communicatively connected to the AP. Figure 1 In the present invention, wireless communication between non-AP STAs is formed with the help of AP. However, when a direct link is established between non-AP STAs, STAs can communicate directly with each other (without using AP).

[0057] Figure 2 Conceptually, an electronic system that can be used to implement aspects of the present invention described herein and in the appendix is ​​shown. For example, the electronic system 200 can be a network device, a media client, an Internet Protocol (IP) set-top box (STB), a desktop computer, a laptop computer, a tablet computer, a server, a switch, a router, a base station, a receiver, a phone, or any electronic device that transmits a signal via a network in general. This electronic system 200 includes different types of computer-readable media and interfaces for various other types of computer-readable media. The electronic system 200 includes a bus 208, one or more processors 212, a system memory 204, a read-only memory (ROM) 210, a permanent storage device 202, an input device interface 214, an output device interface 206, and a network interface 216, or a subset and variation thereof.

[0058] The bus 208 collectively represents all system buses, peripheral buses, and chipset buses that communicatively connect the many internal devices of the electronic system 200. In one or more embodiments, the bus 208 communicatively connects the one or more processors 212 with the ROM 210, the system memory 204, and the permanent storage device 202. The one or more processors 212 retrieve instructions to execute and data to process from these various memory units in order to perform the processes of the present disclosure. In different embodiments, the one or more processors 212 can be a single processor or a multi-core processor. In one or more embodiments, the one or more processors 212 can implement various processes and methods of the present technology. The one or more processors 212 can also implement Figure 2 The functionality of the first blocks 220 and 240.

[0059] ROM 210 stores static data and instructions required by the one or more processors 212 and other modules of the electronic system. On the other hand, permanent storage 202 is a read and write memory device. Permanent storage 202 is a non-volatile memory that stores instructions and data even when the electronic system 200 is turned off. One or more embodiments of the present disclosure use a mass storage device (e.g., a magnetic disk or optical disk and its corresponding magnetic disk drive) as permanent storage 202.

[0060] Other embodiments use removable storage devices (e.g., floppy disks, flash drives, and their corresponding disk drives) as permanent storage devices 202. Similar to permanent storage devices 202, system memory 204 is a read and write memory device. However, unlike permanent storage devices 202, system memory 204 is a volatile read and write memory, such as random access memory. System memory 204 stores any of the instructions and data required by the one or more processors 212 at run time. In one or more embodiments, the processes of the present disclosure are stored in system memory 204, permanent storage devices 202, and / or ROM 210. The one or more processors 212 retrieve instructions to execute and data to process from these various memory units in order to perform the processes of one or more embodiments.

[0061] The bus 208 is also connected to an input device interface 214 and an output device interface 206. The input device interface 214 enables a user to transmit information to the electronic system and select commands to the electronic system. The input device used with the input device interface 214 includes, for example, an alphanumeric keyboard and a pointing device (also referred to as a cursor control device). For example, the output device interface 206 enables the display of images generated by the electronic system 200. The output device used with the output device interface 206 includes, for example, a printer and a display device, such as a liquid crystal display (LCD), a light emitting diode (LED) display, an organic LED display, a flexible display, a flat panel display, a solid-state display, a projector, or any other device for outputting information. One or more embodiments include a device that acts as both an input and an output device, such as a touch screen. In these embodiments, the feedback provided to the user can be any form of sensory feedback, such as visual or tactile feedback; and the input from the user can be received in any form, including sound waves, voice, or tactile input.

[0062] Finally, if Figure 2 As shown in FIG. 1 , bus 208 also couples electronic system 200 to one or more networks (not shown) via one or more network interfaces 216. In this manner, the computer may be part of one or more networks of computers (e.g., a LAN), a wide area network (WAN), or an intranet, or a network of networks (e.g., the Internet). Any or all components of electronic system 200 may be used in conjunction with the present disclosure.

[0063] Extremely high throughput (EHT) non-AP STA devices will have operating conditions where there are restrictions on transmit (TX) and receive (RX) behavior (e.g., simultaneous TX / RX may be limited for specific link channel combinations for non-AP STAs, also referred to as synchronous mode, also referred to as NSTR (non-simultaneous transmit and receive) links). When a synchronous STA starts TX on a first link (e.g., Link1), the media state of the second link (e.g., Link2) is lost, and the pair of links is referred to as NSTR. In various aspects of the present disclosure, mechanisms and rules are provided to maintain Link2 media state during Link1 TX operation. For example, one mechanism is to synchronize physical layer protocol data units (PPDUs) on both links.

[0064] Terms used throughout this document are defined below.

[0065] A multi-link device (MLD) is a device that can transmit and receive on more than one radio interface link.

[0066] An asynchronous multi-link device (AMLD) is an MLD that is capable of evaluating the medium conditions on at least one other link during transmission on one link according to the required performance constraints of the receiver minimum sensitivity, that is, those two links are asynchronous links.

[0067] A Synchronous Multi-Link Device (SMLD) is an MLD that is unable to evaluate the medium conditions on at least one other link during transmission on one link according to the required performance constraints of the receiver minimum sensitivity, that is, those two links are synchronous links.

[0068] An MLD may have N links, where the relationship between any two links may be synchronous or asynchronous.

[0069] Enhanced Distributed Channel Access (EDCA).

[0070] An EDCA Backoff Suspended Link (EBSL) is a link for which an MLD has suspended EDCA because transmissions by the same MLD on another link have made it impossible to evaluate the media conditions on this link within the required performance limits of receiver minimum sensitivity.

[0071] An Extremely High Throughput Station Set (EHT STA) is a STA that complies with the Extremely High Throughput definition of 802.11TGbe.

[0072] The Synchronous Link Base Station Subsystem (SLBSS) is the BSS in which the MLDs are instructed to attempt to create synchronized transmissions between links.

[0073] Media Access Control Protocol Data Unit (MPDU).

[0074] In aspects of the present disclosure, the rules described herein will assume the case of N links, where N = 2. In aspects of the present disclosure, the rules can be extended to cover more cases of N. The following rule sets are A rules on alignment, B rules on backoff, and C rules on Clear to Send (CTS) and CTA.

[0075] In A Rule 1, the MLD will advertise whether it is operating as an SMLD or an AMLD for a given pair of links, where the advertisement is dynamic (e.g., the relationship can change). Also, the AP MLD will indicate whether any sync-mode MLDs are operating in the BSS. Here, the AP will indicate the condition in beacons and probe responses, the presence of which invokes the use of A, B, and C rules, and the mode of operation is SLBSS.

[0076] In A Rule 2, an MLD transmitting a PPDU to an MLD on a link may request the MLD to transmit a trigger on another link, thereby inducing a response from the MLD on the other link, wherein the MLD receiving the request for the trigger may send this trigger. Also, an MLD receiving a PPDU from an SMLD on Link1 may send a trigger to the same SMLD on Link2. Here, the trigger will include an uplink (UL) length field value that induces a response transmission, the last symbol end time of the response transmission matches the last symbol end time of the PPDU on Link1, and the trigger may induce a single user (SU) PPDU or a high efficiency trigger-based (HE TB) PPDU.

[0077] In A Rule 3, a non-AP MLD may transmit at most one trigger per link, addressed to one user per link, including a TRS type trigger. Also, an MLD that has received two PPDUs with the same end time on two links from one or more MLDs should ensure that the transmitted response PPDUs have the same end time. Furthermore, an MLD that transmits a response to an MLD may include in the response a trigger that causes a PPDU from a different MLD or from the same MLD, with the intent of causing the caused PPDUs to align.

[0078] In A rule 4, for example, if the MLD's associated AP MLD has indicated that synchronization alignment is requested within the BSS, the MLD that initiates the transmission of a PPDU on a link shall attempt to align the last symbol of the transmission with the end of the last symbol of any ongoing transmission on another link. Also, the AP MLD will indicate that synchronization alignment of the transmission is requested within the BSS if at least one associated MLD is operating in synchronization mode. Here, the indication is a dynamic indication and will appear in the operational information of the beacon and probe response.

[0079] In A rule 5, an MLD that initiates transmission of a PPDU on one link during an ongoing transmission on another link should attempt to trigger the response to the PPDU to align with the response to the ongoing transmission, for example, by predicting the response length of the ongoing transmission and by examining the trigger information from the ongoing transmission and using the trigger information to directly determine the length of the response transmission on the other link.

[0080] In A Rule 6, the MLD initiating the transmission of a response PPDU on a link shall attempt to align the last symbol of the transmission with the end of the last symbol of any ongoing transmission on the other link. This occurs if the MLD's associated AP MLD has indicated that synchronization alignment is requested within the BSS, and includes alignment with its own transmissions.

[0081] In A Rule 7, the Insert Trigger should be repeated in multiple MPDUs within a PPDU to allow third parties a chance to receive the information and use it for alignment of their transmissions. The Insert Trigger should also be included as a separate Trigger MPDU at the beginning of the PPDU to be identified earlier when decoding is possible. The Insert Trigger should also be indicated in the New PHY Header field Response Length.

[0082] In A Rule 8, a first new PHY header field is added (eg, Response Length), and a second new PHY header field is added (eg, "Transmit MLD is Sync Mode MLD").

[0083] In A Rule 9, everything becomes simpler if one link just always operates as a trigger-only. Here, the STA that is transmitting a trigger can only transmit a trigger if it knows the conditions on the other link and it creates a trigger that causes the PPDU on the triggered link to align with the ongoing PPDU on the non-triggered link.

[0084] In A rule 10, an MLD that has received two PPDUs with different end times on two links from one or more MLDs should attempt to ensure that the transmitted response PPDUs have the same end time.

[0085] In B Rule 1, the SMLD will suspend the EDCA backoff countdown on a link when transmission by the same SMLD on another link has made it impossible to evaluate the media conditions on this link within the required performance limit of the receiver minimum sensitivity. Here, the network allocation vector (NAV) counter and the BUSY indication based on the PHY length will not be suspended, and the link is called EBSL.

[0086] In B Rule 2, the EBSL of the SMLD shall remain paused until the near-end crosstalk (NEXT) disappears, and 1) the minimum media observation time (MMOT) is executed, or 2) a BUSY media indication is detected using frame detection or energy detection or received media status information before the MMOT time has elapsed, where the media observation time of a link is the time during which there is no transmission on the interfering link and during which attempts are made to confirm the status of the media through detection of frame transmissions from other devices and energy detection (ED).

[0087] In B Rule 3, the SMLD monitors the media on both Link1 and Link2 while not transmitting on either link. Here, if the SMLD begins transmitting on Link1, then on Link2: 1) the In-NAV counter and the Base NAV counter continue to count down if not already at zero, 2) any BUSY indication asserted as a result of the PHY Length field value is maintained per the PHY Length field value, and 3) if the Link1 to Link2 NEXT allows ED operation on Link2 according to the ED threshold, then ED operation continues on Link2 (e.g., if NEXT is above the ED threshold, Link2 will be indicated as BUSY for the duration of the NEXT). In B Rule 3, there is also an optional transmit enable. Here, if both Link2 NAV and Basic NAV are at or reach 0 and any BUSY indication based on the PHY length field value has recovered to IDLE and NEXT is below the ED threshold and ED indicates IDLE, the SMLD may transmit a PPDU from the AC with the lowest current backoff countdown value on Link2 at the Distributed Coordination Function (DCF) Inter-Frame Space (DIFS) after transitioning from BUSY to IDLE of the last of the aforementioned items to obtain its zero or IDLE state.

[0088] In B rule 4, a STA performing EDCA on a link for which the MLO synchronization rule is enabled shall: 1) suspend EDCA function if the start of a preamble is detected on another link of the set of synchronous operations, and 2) restart EDCA function after the PHY header length information has been decoded or failed to be encoded, wherein at this restart, it is not necessary to perform AIFS before restarting the countdown of the IDLE slot. And, if the STA does not suspend its EDCA function on another link of the set of synchronous operations at the start of the preamble, the STA shall use RTS-CTS or RTS-CTA or RTS-trigger when accessing the media on the link, and comply with the timing constraints received in those frames.

[0089] In B rule 5, the MLD operating synchronously may provide media status information to another STA.

[0090] In C Rule 1, an EHT STA receiving a CTS in response to an RTS shall ensure that the sum of 2xSIFS plus (e.g., the time length of the data PPDU it transmits in response to receiving the CTS and the length of the PPDU triggered in response to the data PPDU) is equal to the value of the DUR field of the CTS, where the duration (DUR) field value of the CTS is not equal to the RTS DUR field value minus 2xSIFS (short interframe space) minus the CTS time (e.g., where the CTS time is the amount of time required to transmit the PPDU containing the CTS). Here, a value of 0 may be included in the CTS to indicate: 1) the RTS receiver cannot accept the expected data PPDU at this time, 2) the RTS transmitter should not exhibit a collision failure or a bit error rate (BER) failure. And / or 3) the RTS transmitter may maintain the current contention window (CW) in the backoff process in response to a CTS failure, rather than incrementing the CW.

[0091] In C Rule 2, a CTA response to an RTS is allowed. Here, the CTA contains specific information like the DUR field in the CTS and the subsequent frames, including the PPDU duration, MCS, TX power, other parameters that would normally be found in a trigger frame, and the duration of the BA or other triggered response frame. And, the CTA receiver transmits a PPDU based on the triggered information, including a trigger in the PPDU that triggers a response corresponding to the response duration from the CTA.

[0092] In C Rule 3, the RTS receiver may respond with: 1) a trigger instead of a CTS or CTA, and 2) the choice to respond with a trigger may be made based on the RTS RA value, where i) the RA is set to the RTS receiver's unique MLD address (i.e., an RTS transmitter that addresses an RTS to the MLD address is able to receive a trigger in response), and / or ii) the RTS receiver may choose to attempt to transmit a trigger in response to the RTS without knowing the RTS transmitter's ability to receive such a sequence (e.g., it may just be able to).

[0093] Figure 3 An RTS trigger sequence 300 is shown where the potential loss of MPDUs 310 in Link1 is not a concern and EDCA 320 is shown at the start of the transmission of RTS on Link2 (RTS is the frame marked "R"). In the trigger response to RTS marked "T", the Link1 receiver wins the contention on Link2 and transmits a data PPDU that matches the duration of the Link1 transmission (not shown) or receives an RTS from some other STA and responds with a trigger to force the STA transmission to align with the Link1 PPDU, as shown. The frame marked "C" is a CTS. "BA" is a block acknowledgment frame. "BA+T" is a block acknowledgment combined with a trigger. RA is the receiver address of the frame. TA is the transmitter address of the frame.

[0094] Considering Trigger and TRS, all discussion referring to Trigger Frame can be extended to TRS, where TRS is a shortened form of the Trigger contained in the A-Control field.

[0095] In various aspects of the present disclosure, a trigger modification of the trigger frame described in the IEEE 802.11ax draft revision is provided. For example, any STA is allowed to transmit a trigger in response to an RTS or an initial PPDU as a transmit opportunity (TXOP) (e.g., not just the AP is allowed to transmit a trigger). The trigger should include parameters that cause the triggered PPDU to align with a PPDU on another link. The trigger is modified to include a field indicating that the response to the trigger is a SU PPDU (e.g., not a HE TB PPDU). The existing MU trigger can still be used for this purpose. The trigger may trigger more than one user response, in which case the response will be a HE TB PPDU, not a SU PPDU.

[0096] As another example, the trigger is modified to allow the trigger to specify: allow the receiver to select some parameters of the trigger response PPDU (e.g., the trigger includes some means to signal specific parameters to be selected by the trigger receiver, parameters such as MCS, received signal strength indicator (RSSI) target, spatial reuse, however, the PPDU duration must be present and must be used by the trigger receiver in order to align the PPDU with PPDUs on other link(s). Also, CS is not required for a response to a trigger that is a response to an RTS because when RTS is used to request a trigger, both the RTS and the trigger check the medium before TX so that the CS requirement is already met.

[0097] Thus, the RTS trigger sequence 300 may be useful. For example, the Long Training, Short Training, Legacy Signal (LSIG) fields need to be correctly received from a DATA PPDU on one link to determine the PPDU length, thereby allowing the device to synchronize the PPDU end time on the other link. However, this may not be possible if 1) the RTS transmitter only sees a CTS and not a DATA PPDU, or 2) the two link MACs of the RTS transmitter do not talk to each other (e.g., so that the RTS transmitter does not have information that allows it to synchronize its Link2 PPDU end time with the PPDU end time of Link1. Although the use of triggers solves these problems, an ignore period should be considered between the start of the exchange on Link1 and the determination of the duration of the DATA PPDU on Link1. During this time period, the device that is transmitting the trigger on Link2 does not have enough information to determine the correct value to be included in the trigger to create the desired alignment duration.

[0098] Furthermore, when the RTS DUR field value causes the NAV to be set at a third-party STA, the trigger may not allow a transmission covering the entire NAV duration set by the RTS, and thus the third-party STAs may be stuck with NAV<>0 after the triggered exchange is completed (e.g., those STAs are locked out of the channel due to the difference between the RTS DUR field value and the trigger amount of time after the triggered exchange is completed). To avoid this problem, the RTS DUR field value should be a shorter value, and the trigger response and subsequent DATA PPDUs may provide a longer DUR field value to provide the correct NAV setting, since the trigger response will indicate the final duration. However, the disadvantage is that the RTS receiver does not know how much time the RTS transmitter needs because the DUR is shorter. If a Link1 RTS-CTS exchange is observed before the exchange on Link2 begins, the Link2 RTS should use the same NAV as the Link1 exchange, taking into account the time that has passed between receiving the Link1 RTS and transmitting the Link2 RTS.

[0099] In various aspects of the present disclosure, Figure 4 A delayed trigger sequence 400 is shown where the potential loss of MPDU 410 in Link1 is not a concern because the triggered transmitter on Link2 is operating with an asynchronous link and the EDCA backoff process 420 determines the next transmitter before the frame exchange of Link2 as shown. As shown, if the Link2 EDCA backoff of the STA waiting to transmit the RTS expires in the window from the start of Link1 of the RTS to the completion of the Link1 data PPDU LSIG field, the Link1 PPDU LSIG length is not available in the trigger frame on Link2 within the window 430. Therefore, the responder to the RTS can use techniques to delay the triggered transmission until it has the LSIG length information at point 440 to allow it to determine the appropriate value of the duration to include in the trigger. For example, once the LSIG length is known and can be used to correctly determine the desired aligned trigger frame uplink (UL) length field value that will create the PPDU transmitted in response to the trigger, the responder may send a null data packet (NDP) or two, or otherwise keep the Link2 media BUSY for a duration long enough to reach point 440 and then transmit the trigger.

[0100] In various aspects of the present disclosure, Figure 5 A short PPDU triggering sequence 500 is shown, where the potential loss of MPDU 510 in Link1 is not a concern, and an EDCA backoff process 520 is shown at the beginning of a frame exchange on Link2. Figure 4, the Link1 PPDU LSIG length is not available in window 530, and the LSIG length information becomes available to the trigger transmitter only at point 540. However, here a short trigger 550 is provided in response to the RTS (e.g., a trigger that causes a short response). This is followed by an alignment trigger 560 that matches the remainder of the Link1 PPDU (e.g., a trigger that forces alignment with another link). The short trigger allows the medium to be utilized during the time required by the triggered transmitter in order to obtain information from Link1 to then determine the desired aligned trigger frame UL length field value to create a PPDU transmitted in response to the trigger.

[0101] In various aspects of the present disclosure, when the AP indicates the SLBSS mode of operation, all STAs associated with the AP should initiate a TXOP with an RTS. This may be optional, for example, if the initiating STA has received PPDU length information from a link that is synchronized with the link on which it is initiating a TXOP. In this case, the initiating STA may align its transmission end time with the ongoing PPDU end time without assistance from a trigger.

[0102] In various aspects of the present disclosure, conflict resolution is provided. For example, when STA1 tries to force STAx to align, STAx may have its own TX / RX problems and may want to force STA1 to align. To resolve the conflict, the first frame transmitted in time determines the priority of alignment. This means that no request is converted into a requirement, and each STA receiving the instruction can decide for itself whether to comply.

[0103] In various aspects of the present disclosure, rules are provided that assume a PPDU SMLD indication. These rules are written assuming that each PPDU carries an indication of whether the transmitter of the PPDU is an SMLD. Here, if 1) Link1 transmission indicates that the transmission source is an SMLD or 2) the transmitter on Link2 is an SMLD, then MLD will enforce alignment of the PPDU end time of the new transmission on Link2 with the PPDU end time of the ongoing transmission on Link1.

[0104] In various aspects of the present disclosure, any of the aforementioned information of the PHY header or other information for triggering may be placed in 1) the A-Control field of the MPDU, 2) within a trigger frame, 3) within a new frame, or 4) within a PHY header.

[0105] As discussed above, an EHT non-AP STA device (e.g., a device compliant with IEEE draft 802.11be) will have operating conditions where there are restrictions on TX / RX behavior such that when a sync STA starts TX on Link 1, the ability to correctly determine the media state of Link 2 is significantly impaired. In various aspects of the present disclosure, a mechanism to maintain the Link 2 media state during Link 1 TX operation is that the receiver of Link 1 TX supplies Link 2 state information to the transmitter of Link 1 TX.

[0106] For example, if Figure 6 As shown in , there is often a synchronous transmitter EDCA problem to be overcome, as shown in the frame exchange sequence 600 mediated by EDCA. Here, the dark gray box is STA1 TX, and all other boxes are STA1 RX. As shown, STA1 non-AP STA is the first TXOP winner as shown, where STA1 starts TX frame exchange to STAw on Link1. When STAx attempts to transmit to STAw during STA1 Link1 TX, STA1Link1 TX NEXT causes RX failure at STA1 Link2. At the end of TX on Link1, STA1 recognizes Link2 as IDLE unless the received energy of TX on Link2 is greater than -62dBm at STA1's location, but there is no rule regarding STA1 Link2 idle channel assessment (CCA) sensitivity during Link1 TX. Here, assuming that the received energy of TX on Link2 is less than -62dBm, the STA1 Link2EDCA backoff quickly restarts at point 610 and counts down to 0, allowing a new TXOP attempt by STA1 on Link2, which begins with an RTS transmission marked "R". STA1 TX of RTS to STAw on Link2 causes an error in the reception of the existing Link2 PPDU at the receiving STAw (e.g., STAw=AP) at point 630. This error may cause a moderate loss of DATA because a long PPDU may contain multiple separately verified data blocks. But if the interference caused by the RTS transmission at point 620 causes an incorrect decoding of a BA (block acknowledgement) frame, the entire previous DATA PPDU will be considered lost, resulting in severe degradation of system performance.

[0107] In various aspects of the present disclosure, Link2 Media Status Information (MSI) is provided to the MAC function operating on Link1. Here, the AP (STAw) knows that Link1 transmitter STA1 is a synchronous mode STA, potentially as indicated by a bit contained in the PHY header of the PPDU that the AP is receiving on Link1, so that the AP does not have to look up the information based on the TA value of the MPDU in the PPDU. Although the AP is Figure 6 , but STAw may be any asynchronously operated device (e.g., non-AP). The AP provides media state information for Link2 to STA1 in response to STA1 TX to the AP. For example, the AP provides duration / end time information of the simultaneous Link2 PPDU and duration / end time information of the simultaneous Link2 NAV in its BA response to STA1 on Link1 or in a PPDU containing the Ba response. Thus, the MSI delivery may be a new PPDU constructed to hold this MSI information, an empty data PPDU with an A-Control field containing the MSI information, and / or in a PHY header field constructed to hold the MSI information.

[0108] like Figure 7 As shown, a synchronous transmitter EDCA sequence 700 illustrates a solution according to aspects of the present disclosure. Here again, the dark gray box is STA1 TX, and all other boxes are STA1 RX. As shown, STA1 receives MSI with the BA on Link1. For example, STA1 cannot accurately determine the Link2 media condition as IDLE until it has MSI information, STA1 Link2 deafness disappears at the end of STA1 TX PPDU, STA1 MSI information is determined at the end of STA1 RX PPDU BA+MSI, and STA1 should suspend EDCA at the end of RX PPDU BA+MSI until MSI information is available (e.g., L2 EDCA HOLD, as shown). Figure 6 Therefore, STA1 uses MSI to adjust the Link2 media state (eg, setting CRS, setting NAV for Link2), and subsequent operations are performed based on normal EDCA.

[0109] The MSI latency may cause problems. Because the MSI information is in the response frame, it is not available when Link2 goes deaf for the first time, and if Link2 is IDLE at the time, STA1 is performing unnecessary EDCA maintenance (e.g., as long as MSI is not yet available).

[0110] According to aspects of the present disclosure, the Link2 IDLE indication may be included in the PHY header. For example, when Link2 is IDLE at the end time of Link1 PPDU according to information obtained at the BA transmitter location, the Link2 IDLE indication may be asserted in the PHY header of the BA+MSI. Therefore, this information is available much earlier in the RX PPDU, and this shortens the waiting time for Link2 EDCA resynchronization.

[0111] In some aspects of the present disclosure, the MSI time in the PHY header may transform the link IDLE information into a full wait time (e.g., simply placing the Link2 BUSY duration in the PHY header of the response frame). Here, a value of 0 indicates Link2 IDLE, and a non-zero value is equivalent to supplying a Link2 remaining PPDU length and / or a Link2 remaining DUR NAV value (e.g., equivalent to a PHY header TXOP value but referring to another link, equivalent to a PHY header MSI, or a subset of the MSI).

[0112] like Figure 8 As shown, the MSI is carried in an MSI frame as an MPDU 800. Here, the MSI control contains a bitmap indicating the presence or absence of per-link media status information, where a "1" in the bitmap indicates that the MSI is present for a link having a link identification (LinkID) corresponding to the position of the bit in the bitmap, and a "0" indicates that the MSI is not present for the corresponding link. The MSI block contains N copies of the per-link MSI, where N is equal to the number of bits equal to "1" in the MSI control bitmap, and the per-link MSI fields that are present are arranged in ascending order of LinkID.

[0113] Each link MSI may contain three subfields. The first subfield, MSI_NAV_INTRA, contains the predicted value of the intra-frame NAV of the MSI MPDU transmitter of the corresponding link at the end of the last symbol of the PPDU carrying the MSI MPDU. The second subfield, MSI_NAV_BASIC, contains the predicted value of the basic NAV of the MSI MPDU transmitter of the corresponding link at the end of the last symbol of the PPDU carrying the MSI MPDU. The third subfield, MSI_LEN (length), contains the predicted value of a counter at the transmitter of the MSI MPDU that counts down the PHY length field value after receiving a valid PHY header containing PHY length field information for the corresponding link (e.g., the remaining PHY length value at the MSI transmitter of the specified link at the end of the PPDU carrying the MSI).

[0114] The subfields may all have unsigned positive values, with a minimum value of 0, where values ​​may be expressed in microseconds or some larger time unit. Alternatively, the subfields may have positive or negative values. A positive value indicates a future time when the indicated media state variable is expected to change from BUSY to IDLE, starting from the end of the PPDU containing the MSI. A negative value indicates a time before the end of the PPDU when the indicated media state is expected to have changed from BUSY to IDLE. If a negative value is used, the receiver may use the negative value to adjust its relevant EDCA parameters downward relative to the magnitude of the value.

[0115] In various aspects of the present disclosure, the PHY header may contain a bit per link indicating MSI IDLE. For example, one bit per link indicates MSI IDLE or BUSY. Therefore, if this bit indicates link BUSY, the receiving MLD should check the received MPDU in the same PPDU for more detailed information, such as MSI_NAV_BASIC, MSI_NAV_INTRA, MSI_LEN (e.g., "1" indicates IDLE). The PHY header may contain a more complete MSI field per link (e.g., MSI_NAV_BASIC, MSI_NAV_INTRA, MSI_LEN, as described in the MSI frame). The IDLE state is indicated by all fields having a value of 0.

[0116] In aspects of the present disclosure, MSI receiver behavior may be provided. For example, an MLD operating in synchronous mode will suspend EDCA operation on any other link on which the MLD is unable to evaluate the media state according to the performance requirements of the receiver minimum sensitivity during transmission on the link. Here, suspending EDCA means operating as if the affected link is experiencing a media BUSY state. With respect to the MSI receiver MSI_LEN counter, the MLD operating in synchronous mode will support MSI exchanges and implement an MSI_LEN counter for each operating link, wherein the MSI_LEN counter for a link will be set to the value of the received MSI_LEN field of that link, and will count down the appropriate time units starting at the end of the last symbol of the received PPDU containing the MSI_LEN field, and will (although non-zero) imply a BUSY condition on that link in accordance with the IDLE state indication previously described.

[0117] In various aspects of the present disclosure, a STA receiving the MSI for a particular link shall, for that link: 1) replace the intra-frame NAV counter value with the received MSI_NAV_INTRA value after appropriate scaling, provided that the scaled received value is greater than the intra-frame NAV value at the end of the last symbol of the PPDU containing the MSI MPDU, and 2) replace the basic NAV counter value with the received MSI_NAV_BASIC value after appropriate scaling, provided that the scaled received value is greater than the basic NAV value at the end of the last symbol of the PPDU containing the MSI MPDU.

[0118] In aspects of the present disclosure, after a transmission by the MLD on a link that requires suspending EDCA on another link, the MLD may resume EDCA operation on the link on which it was suspended, for example, 1) at the end of a valid PHY SIGNAL field of a PPDU received on the link on which it was previously transmitting, when the received PHY SIGNAL field contains an MSI indication for the suspended link (e.g., complete MSI information or an indication that the suspended link is IDLE), 2) at the end of the last symbol of a PPDU received on the link on which it was previously transmitting, when the received PPDU contains an MPDU that includes an MSI for the suspended link, and 3) at any time after the end of transmission, provided that it receives any valid PPDU PHY header on the suspended link.

[0119] In various aspects of the present disclosure, if an MSI parameter for a link is received with a negative value in a PPDU, the receiver of the MSI may perform adjustments to its backoff process on the affected link (e.g., the backoff should be calculated at the end of receiving the PPDU containing the MSI, assuming that the magnitude of the negative value of the parameter is effectively the amount of IDLE time that has elapsed before the end of the PPDU). For example, if all MSI parameters indicate zero or a negative value, then at the end of reception of the PPDU, the receiver determines the earliest time from the end of the PPDU when all parameters have reached zero, indicating a summed IDLE indication for the link, and the amount of time from that point forward in time to the end of the PPDU is the considered amount of IDLE time for the link that can be used to determine the current state of EDCA for the link. This assumes that the EDCA of the link has already resumed operation when the link is determined to be IDLE (e.g., if the earliest time from the end of a PPDU determined to be IDLE according to the values ​​MSI_INTRA_NAV == -70, MSI_BASIC_NAV == -140, MSI_LEN == -110, then the earliest IDLE later in time from the end of a received PPDU containing MSI information is 70 microseconds from the end of the PPDU). The receiver may then adjust the backoff process to account for the fact that 70 microseconds of IDLE media have elapsed before the end of PPDU reception. If the result of the adjustment is that the existing backoff function of the link will have reached 0 before the end of the received PPDU containing the MSI value, the receiver may use ED and preamble detection to check the current media conditions within a period of one SLOT. If the media is IDLE during the SLOT, the receiver may initiate transmission. If the media is BUSY during that SLOT, the receiver SHOULD restart each expired backoff function by picking a new backoff number either 1) randomly, or 2) by using a number equal to the number of backoff slots between the calculated IDLE media start time and the end of the received PPDU, where this number may be different for each backoff function due to potential differences in the value of the Arbitration Inter-Frame Space Number (AIFSN) for each backoff function.

[0120] In various aspects of the present disclosure, after a transmission is performed by the MLD on a link (e.g., Link1) that requires suspending EDCA on another link (e.g., Link2), if the MSI includes MSI_LEN information for Link2, the MLD will perform an extended interframe space (EIFS) on Link2, starting from a zero time point of a time value determined according to the MSI_LEN value. Here, the MSI_LEN zero point may be in the past (e.g., MSI_LEN may have a negative value) or it may be in the future.

[0121] In various aspects of the present disclosure, a synchronous transmitter indication should be included in the PHY header of a PPDU so that the receiver of this PPDU can prepare the MSI to be included in the response. The indication in the PHY header may be a single bit indicating that the PPDU transmitter is operating using synchronous mode.

[0122] In various aspects of the present disclosure, uncorrelated transmission alignment (UTA) is provided. EHT non-AP STA devices may have operating conditions where there are restrictions on TX and RX behavior (e.g., simultaneous TX / RX may be limited for a specific link channel combination of a non-AP STA, also known as a synchronization mode). Non-AP STAs may attempt to control the timing of the start and / or end of transmission, but cannot control the start and / or end of reception (i.e., to minimize destructive overlapping activities). UTA helps create alignment of the start and / or end times of uncorrelated transmissions to reduce destructive overlap.

[0123] In various aspects of the present disclosure, there are several EDCA rules for deaf links (i.e., links for which devices are unable to correctly determine media conditions or states). 1) Link1 STA initiates TX, i.e., Link1 backoff == 0. 2) Link2 NO synchronous TX is possible (e.g., Link2 backoff == 0 does not occur at the same time). 3) Link2 EDCA is deaf on Link2 (i.e., unable to correctly determine media conditions or states), which is due to Link1 TX inter-device interference. Here, Link2 indicates media BUSY due to NEXT (near-end crosstalk) during Link1 TX, and Link2 EDCA is in SUSPEND due to the BUSY indication. In some aspects of the present disclosure, different implementations may not indicate BUSY. 4) Link1 TX is completed, so the question is, what happened on Link2? For example, if Link2 EDCA gets out of sync with any other Link2 activity, can Link2 EDCA be restarted immediately, or is a waiting time required (e.g., similar to the waiting time recommended when a device transitions from a DOZE state to an AWAKE state). 5) Note that for devices with inter-device interference, Link2 becomes deaf during each Link1 TX, and the resulting EDCA on Link2 is not "true EDCA" and is undesirable because it is a "partial EDCA" because the media conditions on Link2 are only temporarily and partially correctly determined, i.e., only during those time periods when no transmissions occur on Link1. For example, this is considered worse than quasi-asynchronous mode (i.e., completely deaf vs. partially deaf, i.e., there is a partial ability to determine some aspects of the media conditions on Link2 during transmissions on Link1, for example, the ED may continue to operate in a smaller received energy range between the interference level from Link1 TX and the ED threshold).

[0124] In various aspects of the present disclosure, techniques for PPDU alignment between Link1 and Link2 make EDCA deafness non-critical. That is, when PPDU alignment occurs, Link2 is required to indicate BUSY during Link1 TX, and then when Link2 hearing is restored (i.e., deafness ends), the preamble may start or the medium has become idle (i.e., once PPDU alignment is achieved, deafness Link2 EDCA remains synchronized because Link1 and Link2 PPDUs are in sync).

[0125] These techniques assume a STA with N links, with most discussions assuming N == 2. TX TX indicates that a given STA is transmitting on Link1 and transmitting on Link2 simultaneously, but not necessarily completely overlapping (e.g., the start and end times of the transmissions are not assumed to be aligned, at least initially). In some aspects of the present disclosure, alignment of TX start and / or end times may exist for various scenarios. TX RX indicates TX on one link, RX on the other link, not necessarily aligned. RX RX indicates RX on both links. RX TX indicates RX on one link, TX on the other link, the difference between TX RX and RX TX is related to which event started first in time.

[0126] The desired result of these techniques is to keep EDCA working effectively on all links, even in the presence and in the presence of synchronous mode STAs. This is easier for two links and more difficult for three links. And, with these techniques, synchronous mode STAs are able to use two (or N) links simultaneously, which can achieve significant increases in throughput and reduced latency. Here, the primary target is the TX TX and RX RX scenarios, and the secondary target is the TX RX and RX TX scenarios.

[0127] Fig. 9 A basic TX RX case 900 in various aspects of the present disclosure is shown. The dark gray area indicates STA1 TX, and all other areas indicate STA1 RX. Here, STA1 non-AP STA is the first TXOP winner and starts TX on Link1. STA2 attempts to transmit to STAx during STA1 Link1 TX, where STA1 Link1 TX NEXT causes RX on Link2 to go deaf. And, this is a typical infrastructure UL (uplink) case (e.g., STAx is the AP of STA1, STA2, so the transmission is all uplink to AP). STA1 Link2 becomes EDCA asynchronous, and STA1 may start a new TX on Link2 while STA2 is still transmitting effectively on Link2. As shown, the detection indicator 910 indicates the point of STA1 potential failure to detect PPDU, and the idle indicator 920 shows where STA1 indicates media IDLE, assuming that the received energy of the PPDU detected by STA1 at the idle indicator 920 is lower than the ED threshold (e.g., a typical value of -62dBm).

[0128] Fig.10An advanced TX RX case 1000 in various aspects of the present disclosure is shown. The dark grey area indicates STA1 TX, and all other areas indicate STA1 RX. Here, STA1 non-AP STA is the first TXOP winner and starts TX on Link1. STAw attempts to transmit to STA1 during STA1 Link1 TX, where STA1 receives RTS, sends CTS, but Link1 TXNEXT causes RX failure of Link2 data PPDU. If STAw is the AP of STA1, STAw will usually simply not start the indicated Link2 PPDU TX (i.e., if Link1 TX RA == STA1's AP, then the AP checks the TA and should not TX to STA1 on Link2), but in some examples, the AP function of Link2 is unaware of the reception on Link1, or the information identifying the transmitter of the PPDU on Link1 is not available at the time of the RTS transmission on Link2. However, for the tunnel direct link setup (TDLS) case, the transmitter of Link2RTS is not the AP, but some STA2 and STA2 may not be aware of STA1's Link1 TX. In either case, STA1 may choose not to respond to the RTS being transmitted by STA2, knowing that it is likely to fail to receive the subsequent data PPDU. Here, the RTS may be retried in vain due to the missing CTS, the STAw (or STA2) CW increases due to the wrong reason (i.e., the missing CTS is usually considered to be due to contention, in which case the CW should be increased, but in this case, congestion is not the cause of the failure), and / or STAw (or STA2) believes that the MCS is incorrect or that STA1 has disappeared (i.e., no longer operating on Link2). As shown, segment 1010 indicates that the RTS may be lost due to Link1NEXT, segment 1020 indicates the potential loss of the MPDU, and segment 1030 shows that STA1 indicates media IDLE.

[0129] In various aspects of the present disclosure, it is implemented to have a synchronous mode STA use two links at a time (e.g., TX TX, RXRX). For example, for the TX TX case, TX+TX will not suffer from the harmful effects from self-interference, and when the non-AP STA1 acquires one link, say Link1 (e.g., STA1 Link1 TX starts), the problem here is how STA1 can use EDCA on Link2 to simultaneously acquire Link2 for TX (i.e., when Link1 TX is active, Link2 EDCA becomes deaf / BUSY). The solution is to be triggered by other STAw, where EDCA is checked at Link2 by the triggering STAw (e.g., STAw is asynchronous and does not experience EDCA deafness on Link2 when transmitting on Link1), and allow the AP (STAw) and non-AP STA to perform as Fig.11 Double trigger operation shown.

[0130] Fig.11A UTA TX TX trigger case 1100 is shown. The dark grey area indicates STA1 TX, and all other areas indicate STA1 RX. Segment 1110 indicates frame exchange on Link1, segment 1120 indicates STAw EDCA, and segment 1130 indicates potential loss of MPDU, i.e., loss of trigger PPDU at STA1 due to STA1 Link1 TX. For this UTA ​​TX TX trigger case, STA1 is the first TXOP winner and starts TX on Link1, where STA1 Link2 EDCA indicates BUSY due to NEXT from Link1 TX (e.g., STA1 Link2 EDCA must be paused), and STA1 may include a trigger request in its TX PPDU. And, STAw continues to perform EDCA on Link2 as indicated at 1120 (i.e., STAw is asynchronous mode MLD), where STAw completes EDCA backoff and transmits the trigger indicated at 1130 (e.g., the trigger indicates MCS, with PPDU LENGTH, which should synchronize the end time of the triggered PPDU with the end time of the ongoing Link1 TX). In addition, STA1 transmission on Link1 may include a request for triggering on other links, where the trigger is not always receivable due to NEXT. Therefore, the trigger request may take NEXT into account (e.g., if the trigger will fail to RX, then the trigger request is not sent), and the request may include an MCS suggestion for the trigger or a suggestion for no trigger at all. When a trigger is transmitted to STA1, where an AP or non-AP STA (e.g., TDLSSTA) optionally transmits a trigger, it should transmit a trigger only if it knows that the trigger is receivable (e.g., signal-to-noise-and-interference ratio (SINR) estimate + MCS), transmit only if it knows that the synchronization mode STA1 can perform the CS required check (e.g., Link1->Link2 NEXT level allows STA1 Link2 to perform a -72dBm CS check), and include a triggered PPDU duration (UL length) that matches the ongoing Link1 TX to synchronize the PPDU. When STA1 does not request a trigger, STAw may transmit a trigger to STA2, which does not transmit on Link1 and therefore does not have a NEXT on Link2 that would cause a failure to receive the trigger. In this case, the trigger includes a triggered PPDU duration (UL length) that matches the ongoing Link1 TX to synchronize the PPDU.

[0131] Additional UTA TX TX considerations include STA1 sending the requested trigger. Here, STA1 may send the request without full knowledge of the probability of receiving the trigger (i.e., assuming the trigger transmitter makes the decision), where 1) if the trigger is transmitted to STA1, it may not be received, 2) if the trigger is received, it may be that STA1 does not respond due to other considerations such as new interference, and 3) the trigger transmitter may postpone the trigger transmission to a later time or transmit the trigger to a different STA. And, instead of responding to the trigger request with a trigger, the requested device may transmit a CTS addressed to STA1, thus providing a similar result to providing STA1 with permission to transmit.

[0132] Fig.12 A TX TX RTS trigger case 1200 is shown. Segment 1210 indicates that STA1 EDCA counts down to 0 and starts TXOP with RTS transmission, segment 1220 indicates that STAw EDCA counts down to 0, and segment 1230 indicates data PPDU. For this TX TXRTS trigger case, the MLD AP has declared Link2 as triggered only to make it easier to predict the future results of Link2 EDCA backoff countdown, but this is not necessary, and STA1 is the first TXOP winner and starts TX on Link1 with RTS. Here, 1) STAw estimates the time when backoff == 0 on Link2 (e.g., possibly after RTS reception), 2) STAw prepares the Link1 triggered response to RTS based on the expected start time of the trigger on Link2, which is the time when Link2 EDCA backoff reaches 0, so that the triggered PPDU end time is aligned (e.g., to create a Link1 trigger that is longer than required, but whose length accommodates the completion of Link2 EDCA backoff and the subsequent transmission of the trigger on Link2), and 3) STAw prepares Link1 and Link2 triggers to have the same triggered response PPDU end time, i.e., with the same UL length field value. Therefore, due to the trigger-only limited operation on Link2, the Link2 EDCA backoff == 0 time is completely predictable. And, the data PPDU potentially requires TRS or triggers to ensure that the BA response PPDU duration is equal for those cases where additional PPDUs are transmitted in the TXOP on the link.

[0133] Fig.13Another TX TX RTS triggering case 1300 is shown. Segment 1310 indicates that STA1 EDCA counts down to 0, segment 1320 indicates that STAw EDCA counts down to 0, and segment 1330 indicates that STAw chooses to delay transmission on Link2. For this TX TX RTS triggering case, the MLD AP has declared Link2 as trigger-only in order to more easily predict the future results of Link2 EDCA backoff countdown, but this is not necessary, and STA1 is the first TXOP winner and starts TX on Link1 with RTS. Here, 1) STAw sees the start of RTS transmission, 2) STAw Link2 backoff expires during or even before RTS reception (e.g., the backoff on Link2 may have expired long before Link1 RTS reception starts), where in any case, STAw optionally waits for the results of RTS reception and then transmits on Link2, 3) STAw detects the opportunity for parallel triggers to STA1 on Link1 and Link2, and 4) STAw transmits parallel triggers to STA1 on Link1 and Link2.

[0134] For these TX TX RTS triggering cases 1200, 1300, in general, 1) the AP wins contention on Link1 and Link2 simultaneously, or by delaying transmission on the first link on which it won contention, and starts parallel synchronous transmissions to one or more receivers, or 2) a non-AP STA wins contention on Link1 and the AP responds to an RTS or request for trigger (RFT) transmitted by the winning STA with a trigger on Link1 and optionally on Link2. This second option includes triggering with a common end time, where the trigger on Link1 is sent to the RTS / RFT transmitter, and the trigger on Link2 is sent to the RTS / RFT transmitter or another STA, and the AP optionally transmits data on Link2 to the other STA in a PPDU with an end time synchronized with the end time of the Link1 transmission (e.g., TX RX case). Here, synchronization in this case means a common start and end time of the PPDU, or at least a common end time. It is typically preferred to perform contention only on Link1 and trigger Link2 only for the uplink (i.e., data transmitted by a non-AP to the AP), where the AP has normal access to the downlink on Link2 but typically attempts to synchronize those downlink PPDU end times with the end time of the PPDU on Link1.

[0135] Some additional TX TX rules may include that only one link follows normal EDCA operation for non-AP STAs (e.g., only trigger other links (i.e., the number of links may be greater than 2.) and that any STA is allowed to TX trigger (i.e., not only APs), such as where non-APs only send modified triggers (i.e., no MU response PPDUs, only SU PPDU transmissions in response to triggers transmitted by non-AP STAs). In addition, it is generally preferred to maintain PPDU alignment between links (e.g., common start and end times of PPDUs, at least common end times). And, create an alternative to RTS (e.g., RFT trigger request), which is similar to RTS but also includes information in RFT about: 1) whether the RFT transmitter requires triggers on any other links, and if so, which links; and 2) the desired length of the trigger-induced transmission. In some cases, the response to a triggered Link2 PPDU may not match the length of the response to the Link1 PPDU, in which case the technique may provide response length information in the trigger to ensure that the two responses match, but this is not necessary if the responder is the same on both links (e.g., if the responder is the same, then the responder should align with the end time of the response PPDU).

[0136] In various aspects of the present disclosure, a case of switching TXOP owner is provided, where if the AP estimates that the Link1 transmitter will not receive a trigger, the AP will most likely trigger a different STA. Here, if the AP triggers a different STA, the AP aligns the link transmissions using the trigger parameters. And, at the end of the aligned Link1 and Link2 transmissions, the AP responds with a BA on each link. Here, the AP may change the TXOP owner on Link2, where the AP may be encouraged to do so through a trigger request (e.g., an immediate trigger to the requester is not possible, so switching the TXOP owner is a delayed response to the trigger request).

[0137] Fig.14A UTA TX TX triggered swap case 1400 is shown. The dark grey area indicates STA1 TX, and all other areas indicate STA1 RX. Segment 1410 indicates a frame exchange in a TXOP initiated by STA1, segment 1420 indicates STAw EDCA, segment 1430 indicates a BA transmission with RA==STA1, and T is a trigger included in a PPDU containing a BA, where the trigger is for STA1, and segment 1440 indicates a BA transmission with RA==STA2, but T indicates that the accompanying trigger within the PPDU containing the BA is for STA1. For this UTA ​​TX TX triggered swap case, STAw initially triggers STA2 on Link2 because the triggered reception will fail for STA1 on Link2 due to the interference at STA1 Link2 caused by the ongoing STA1 TX on Link1. Here, STA1 resumes monitoring Link2 at the end of Link1TX, the STAw BA response on Link2 includes a trigger for STA1 (ie, a delayed response to the optional trigger request), and STA1 is now transmitting synchronously on Link1 and Link2.

[0138] In various aspects of the present disclosure, TX TX priority access is provided. For example, the media access rules may allow the Link1 transmitter to initiate transmission on Link2 when the previously obtained NAV and PHY header LENGTH information on Link2 has expired before the end of transmission on Link1 (i.e., Link2NAV, CRS LENGTH is obtained before TX on Link1 starts), and without considering the backoff countdown. Here, the media access rules may optionally allow only intra-BSS NAV to be used when making a decision to transmit on Link2 when Link2 NAV and LENGTH expire during transmission on Link1 (i.e., ignoring inter-BSS NAV). And, when the last Link2 NAV, LENGTH expires, 1) any fully active EDCA STA competing on Link2 will restart its backoff (i.e., not start TX), and 2) STA1 can access Link2 after LIFS without restarting backoff. Due to this combination of conditions, there is no other contention for Link2 because everyone else has a non-zero backoff, and there is only one TX priority access STA from Link1 (i.e., STA1) because there is only one winner on Link1. Optionally, priority access is allowed only if the PPDU active on Link2 during the NAV of Link2 is indicated as having the same BSS color as STA1 transmitting on Link1.

[0139] Fig.15TX TX priority access case 1500 is shown. The dark gray area indicates STA1 TX, and all other areas indicate STA1 RX. Segment 1510 indicates STA1 EDCA, segment 1520 indicates STA1 NAV, segment 1530 indicates STA1 LIFS, and segment 1540 indicates the observed STA1 BSS color (optional). LIFS has a link IFS (e.g., delay [SIFS, SIFS+2xSLOT]) without checking the media. Here, Link2 RTS CTS is missing, where RTS CTS exchange is not possible because STA1 cannot RX CTS on Link2. TXTX priority access may be allowed only when the previous occupied PPDU on Link2 is an intra-BSS PPDU (e.g., a STA1 BSS color match is observed in a PPDU within a previous Link2 exchange). The previous Link2 exchange may be a longer sequence. For example, the BA may be followed by another data PPDU (e.g., the NAV value does not anticipate another transmission). Here, it may add a bit to the PHY header to indicate whether another PPDU will follow (i.e., a bit indicating that this PPDU is the second to last PPDU of the sequence, this bit is set to "1" in the PHY header of the data PPDU, where TA=STAw). If the bit is present, then optionally, the priority access rule may only allow priority access when the discovery bit is set to "1".

[0140] In various aspects of the present disclosure, RX RX cases with one receiver are provided. For the useful case, the RX on Link1 does not interfere with the RX on Link2, however, there is a response transmission triggered by the receive that will create a TX RX case. For the simple case, 1) an asynchronously capable AP acquires Link1, initiates TX to STA1, and 2) during AP TX on Link1 to STA1, the AP acquires Link2 (e.g., the AP may cause the TX PPDU on Link2 to align with Link1 TX to avoid undesirable overlap). For the more difficult case, the PPDU reception at STA1 on Link1 and Link2 is from unrelated sources.

[0141] Fig.16RX RX operation has one reception scenario example 1600. The dark gray area indicates STA1 TX, and all other areas indicate STA1 RX. Segment 1610 indicates STAx EDCA, segment 1620 indicates potential loss of MPDUs, and segment 1630 indicates potential loss of PHY headers and all MPDUs contained within the entire PPDU to which the PHY header belongs. For this RX RX operation has one reception scenario example 1600, STA1 receives misaligned PPDUs from unrelated transmitters on two links. And, some interference is more damaging than other interference (e.g., a lost PHY header means that the entire PPDU is lost, interference occurring in the middle of a PPDU causes some bit errors, but if the PPDU contains an aggregated MPDU (AMPDU), only those MPDUs of the AMPDU that have bit errors caused by interference will fail due to interference.). Aligned RX PPDU end times will prevent this loss.

[0142] Fig.17 An uncorrelated transmit alignment case 1700 is shown. Segment 1710 indicates STAx EDCA, segment 1720 indicates a potential loss of an MPDU, segment 1730 indicates a duration of 2000, and segment 1740 indicates a duration of 3000. For this uncorrelated transmit alignment case 1700, Link2 RTS DUR == 9500 and Link2 CTS DUR == 3000 (e.g., negotiated DUR). Also, CTS indicates the amount of time available for PPDU+BA to create an alignment operation with activity on Link1, where STAx follows the CTS DUR in its subsequent PPDU transmissions, rather than the initially indicated RTS DUR, thereby causing RX / TX alignment. In some aspects of the present disclosure, STAx may read the PHY LEN from Link1 TX (e.g., use the PHY LEN to create alignment). In addition, BA+Q is an AMPDU containing BA+Quality of Service (QoS) data, where there are enough symbols to align the next transmissions in the sequence (e.g., force TXOP sharing).

[0143] Fig.18A UTA RX RX with T case 1800 is shown. Segment 1810 indicates STAx EDCA, segment 1820 indicates potential loss of MPDU, segment 1830 indicates duration of 2000, segment 1840 indicates duration of 3000, segment 1850 indicates T, and segment 1860 indicates same transmitter. For this UTA ​​RX RX with T case 1800, BA+T contains AMPDU BA information plus a trigger containing time / DUR information, where the time / DUR information indicates the exact duration of the next PPDU requested by the trigger. Other information similar to the trigger is also included (e.g., TX power, target RSSI, MCS, etc., as optionally required), as well as the recommended BA duration (e.g., in this example, it is the same BA transmitter on both links, so they should be aligned). Also, a trigger (T) is present in a PPDU containing a BA MPDUS only if there is a next PPDU, since the extra T information is intended to create alignment for the subsequent PPDU, whereas if there is no subsequent PPDU, T is not required.

[0144] In some aspects of the present disclosure, BA responses may not initially have the same length. Here, if the response transmissions are from the same transmitter, the transmitter of the responses should ensure that the end times of the responses on different links are aligned. This alignment can be achieved in various ways, including modifying either or both frames via the following operations: 1) adding or subtracting patches, 2) adding or subtracting frame delimiters, 3) modifying the MCS or other encoding to change the duration of the response by changing the bit rate of the frame, 4) adding information bytes to the response frame, 5) subtracting information bytes from the response frame, where preferably the shorter frame is extended. Therefore, in general, all STAs should always try to ensure that the end of any transmitted PPDU is aligned with the end of any ongoing PPDU on the other link(s). This may apply to other cases besides the RX RX case.

[0145] In various aspects of the present disclosure, for the RX RX case, any STA monitoring Link1 and Link2 may be able to determine 1) the RA of the first PPDU on Link1, and 2) avoid starting a TX on Link2 to the same RA, or may synchronize the Link2 TX PPDU end time with the PPDU end time on Link1. This can only be achieved when the Link2 transmitter can determine the RA of the Link1 RX PPDU in the MAC header, where the SINR, MCS may not allow this information to be decoded correctly. Therefore, an AID value may be used, which may be present in the PHY header that needs to decode the lower SINR correctly, and where the AID value with the accompanying MAC address value should be delivered to all STAs in the BSS, which requires a lookup operation AID->MAC address. And, a simple solution is to always synchronize any new TX with any ongoing TX to avoid such lookup operations.

[0146] In various aspects of the present disclosure, there are several RX RX rules. For example, any STA monitoring Link1 and Link2 should determine whether Link1 transmitter STA1 is synchronized, such as by checking the indication in the PHY header of the Link1 PPDU that "I am a synchronous mode STA", or by checking other information in the MAC header (e.g., TA is combined with the capability information previously exchanged in other connection establishment and capability announcement frames). If the Link1 transmitter is synchronized, any STA transmitting on Link2 should create an alignment with the PPDU on Link1, regardless of the source and destination PPDUs on Link1. This allows STA1 to remain synchronized with the EDCA channel conditions on Link2, even when it is deaf on Link2 due to the NEXT from Link1 TX. An example easier rule is that all STAs always align their TX end time with any existing "other link" TX PPDU end time, which means that there is no need for an "I am a synchronous mode STA" indication. This applies to all combinations of RX, TX. As another example, the AP may set such a rule or recommendation for the BSS, or not do so (e.g., always align or not align based on known membership of the BSS, or just to be safe), and announce the need for the rule or recommendation by transmitting an indication within a beacon.

[0147] In aspects of the present disclosure, for RX RX response frames, the response frames to the RX frames may not be synchronized. For example, if the same receiver is generating parallel responses on >1 link, the receiver should add symbols to the shorter response to make it the same length as the longer response to maintain alignment of the PPDUs on both links. This is independent of the source of the initiating frame and independent of the multi-rate rules for response rate selection (i.e., the resulting shortest response frame should increase in length to match the longer response frame, thereby making the shorter response frame an exception to the existing rule).

[0148] Fig.19 RX RX operation with two receive scenarios example 1900 is shown. Segment 1910 indicates STAw EDCA, segment 1920 indicates undesired loss of EDCA synchronization with Link2 media conditions at STA1, segment 1930 indicates Link2 EDCA synchronization recovery at STA1, and segment 1940 indicates BA length difference due to MCS BS, etc. of different transmitters. For this RX RX operation with two receive scenarios example 1900, there are two receivers from the same source (e.g., STAw asynchronous, such as APMLD). Here, the transmitter STA2 should create alignment of the transmission, but sometimes this is not possible, in which case the response causes the alignment to be lost. Differences in MCS, BW, etc. between the links may cause the responses to have different lengths, where the transmitter can provide a trigger to induce responses of the same length. If a different receiver will generate a response, the transmitter starting on the second link (e.g., Link2) should predict the length of the response that will be on Link1, align the initial Link2 PPDU with the end time of the Link1 PPDU, and insert a trigger into the Link2 PPDU that will create a response on Link2 to match the response on Link1.

[0149] In various aspects of the present disclosure, an RX TX case is provided. For example, STA1 may want to try RX TX. STA1 can decide whether it wants to do this, but some basic behaviors should be followed to create alignment. For related RX, when RX is intended for STA1, it is unlikely to want to start TX. For unrelated RX, when RX is not intended for STA1, starting TX is normal operation because EDCA continues on another link, but alignment should still be implemented.

[0150] Fig. 20A UTA RX TX unrelated case 2000 is shown. Segment 2010 indicates EDCA, segment 2020 indicates an unconcerned potential loss of an MPDU because the MPDU is intended to be received by a different STA, and segment 2030 indicates T. For this UTA ​​RXTX unrelated case 2000, STA1 is receiving a PPDU on Link1, RA<>STA1, with STA1 EDCA continuing on Link2. And, STA1 is the next TXOP winner on Link2. In addition, STA1 aligns the Link2 PPDU with the Link1 PPDU. Here, STA1 determines the expected Link1 BA response length, STA1 includes the recommended BA length information T to continue alignment to include alignment of the PPDU containing the BA, STA1 reads the BA T information from Link1 to determine the next PPDU length, and when UL == 1, STA1 knows that this alignment worked.

[0151] UTA RX TX Unrelated Case 2000 can use the response time field to create alignment (i.e., provide "T" information, such as Fig. 20 It can also use AMPDU aggregation to pad the response to the appropriate length (i.e., including "Q" data, such as Fig. 20 ). It may also add an uplink indication bit (e.g., UL bit) in the PHY header, where it assumes that there is a color and if the AP advertises asynchronous behavior and UL == 1, the STA may transmit frames to the AP on another link (e.g., if it can tell which STA is transmitting, it may be able to transmit to another STA, so including the AID in the PHY header will help determine this information).

[0152] Fig.21 A UTA RX TX related case 2100 is shown. Segment 2110 indicates EDCA, segment 2120 indicates potential loss of MPDU, and segment 2130 indicates T. For this UTA ​​RX TX related case 2100, STA1 is receiving a PPDU on Link1, RA == STA1. Also, STA1 is the next TXOP winner on Link2, coinciding with the ongoing Link1 RX at STA1 to STA1. In addition, STA1 adjusts the TX power and MCS of Link2 TX to reduce the impact on Link1 RX. Here, the TX power and MCS may be adjusted to different values ​​(i.e., increased TX power, increased MCS) in the later aligned PPDU.

[0153] UTA RX TX Related Case 2100 can use the response time field to create alignment (i.e., provide "T" information, such as Fig.21It can also use AMPDU aggregation to pad the response to the appropriate length (i.e., including "Q" data, such as Fig.21 ). It may also add an uplink indication bit (e.g., UL bit) in the PHY header, where it assumes that there is a color and if the AP advertises asynchronous behavior and UL == 1, the STA may transmit frames to the AP on another link (e.g., if it can tell which STA is transmitting, it may be able to transmit to another STA, so including the AID in the PHY header will help determine this information).

[0154] In various aspects of the present disclosure, a TX RX case is provided. Here, STA1 cannot control the possible initiation of the TX RX case, but STA1 can try to control the alignment.

[0155] Fig. 22 A UTA TX RX unrelated case 2200 is shown. Segment 2210 indicates STAx EDCA, segment 2220 indicates a potential loss of an MPDU by STA1, segment 2230 indicates that STA1 Link2 EDCA media status is correct, segment 2240 indicates that STA1 Link2 EDCA media status is incorrect, segment 2250 indicates that STAx aligns the Link2 PPDU with the Link1 PPDU, segment 2260 indicates the same transmitter used for both links, and segment 2270 indicates that the STAx Link2 PPDU is not aligned with the Link1 PPDU. For this UTA ​​TX RX unrelated case 2200, STA1 is the first TXOP winner and starts TX on Link1, where RX starts on Link2 during Link1 TX. And, STAx continues EDCA on Link2, reaching Backoff == 0, where STAx should align the PPDU and use the PHY header from the Link1 transmission. Furthermore, the BA responses are from the same transmitter, so these can be aligned if STAw deems it necessary.

[0156] Fig.23Another UTA TX RX unrelated case 2300 is shown. Segment 2310 indicates STAx EDCA, segment 2320 indicates potential loss of MPDU by STA1, segment 2330 indicates STA1 Link2 EDCA media status is correct, segment 2340 indicates STA2 combines trigger with BA to continue alignment, segment 2350 indicates STAx aligns Link2 PPDU with Link1 PPDU, segment 2360 indicates the same transmitter for both links, and segment 2370 indicates STAx Link2 PPDU is aligned with Link1 PPDU. For this UTA ​​TX RX unrelated case 2300, STAw combines BA with trigger to force the next PPDU on both links to align. Here, STA1 and STAx include buffer status and / or trigger request information to assist STAw in generating a trigger to be included with the BA.

[0157] In various aspects of the present disclosure, the UTA TX RX unrelated case 2300 may occur when Link1 activity details are not visible to the transmitter on Link2 (e.g., STAx is a single link STA). If STAx is tuned to Link1 and can decode the TA of Link1 TX, and STAx knows that STA1 is only synchronized (e.g., TDLS STAs should know the capabilities), then STAx should not TX to STA1 on Link2. However, STAx may not be able to decode the TA of Link1 TX (i.e., the TX RX case is possible), so the STA ID may be added within the PHY header (e.g., adding AID information to the TDLS setup).

[0158] Fig.24 A UTA TX RX related case 2400 is shown. Segment 2410 indicates STAx EDCA, and segment 2420 indicates a potential loss of an MPDU. For this UTA ​​TX RX related case 2400, STA1 is the first TXOP winner and starts TX on Link1, where RX starts on Link2 during Link1 TX. And, STAx checks the RTS on Link2, where if the RTS is from an EHT STA, STA1 may send a CTS or CTA that specifies PPDU parameters (e.g., MCS, PPDU DUR, end of Link1 TX) that allow RX TX. If the RTS is from a non-EHT STA, STA1 may choose not to respond to the RTS.

[0159] In various aspects of the present disclosure, the UTA TX RX related case 2400 may occur when Link1 activity details are not visible to the transmitter on Link2 (e.g., STAx is a single link STA). If STAx is tuned to Link1 and can decode the TA of Link1 TX, and STAx knows that STA1 is only synchronized (e.g., TDLS STA should know the capability), then STAx should not TX to STA1 on Link2. However, STAx may not be able to decode the TA of Link1 TX (i.e., the TX RX case is possible), so the STA ID may be added within the PHY header (e.g., adding AID information to the TDLS setup).

[0160] In various aspects of the present disclosure, CTA can be used as an additional mechanism. For non-EHT RTS transmitters, the existing CTS is used with non-EHT RTS transmitters, where it cannot affect the alignment of non-EHT PPDUs with CTS. For EHT RTS transmitters, the EHTSTA sends RTS using RA == MAC MLD address (ADDR), and the RA value identifies the RTS transmitter as EHT. This allows the EHTRTS receiver to respond with either a CTS with a DUR for the PPDU restrictions or a CTA frame with more specific explicit information (e.g., PPDU duration, MCS, TX power, etc., BA duration).

[0161] Fig.25 A UTA with T MU DL using CTA case 2500 is shown. Segment 2510 indicates a MU CTS CTA for STA1, segment 2520 indicates a potential loss of an MPDU, segment 2530 indicates a duration of 2000, segment 2540 indicates a duration of 3000, and segment 2550 indicates T. For this UTA ​​with T MU DL using CTA case 2500, there is a MU RTS / MUCTS exchange. Here, the MU CTS response is modified to allow CTA instead of NON HT CTS (e.g., for one user currently active on Link1). Also, the MU RTS transmitter adjusts the DL Orthogonal Frequency Division Multiple Access (OFDMA) PPDU per CTA response. Assuming only one exchange is occurring on Link1, there is only one CTA response to the MU RTS to N users, thereby allowing the MU RTS transmitter to meet the requirement for DL ​​OFDMA PPDU DUR value from only one user, while the remaining MU RTS responders are still sending NON HT CTS.

[0162] In various aspects of the present disclosure, a mechanism for resolving conflicts is provided. For example, STA1 attempts to force alignment by STAx, where STAx may have its own TX / RX problems and may want to force alignment by STA1. Here, the first frame transmitted in time determines the priority. To resolve this issue, no request is converted to a requirement, and each STA receiving the instruction can decide for itself whether to comply.

[0163] In various aspects of the present disclosure, the proposed behavior is provided. For example, the parameters of the non-AP STA indication mode may include a synchronization mode for a given link channel combination, a NEXT level at Link2 when transmitting on Link1, and a TX power indication (e.g., a list of powers per MCS, a current TX power setting that allows non-AP STAs to adjust the level to allow for ED required checks for triggered TX operations). As another example, the AP uses the non-AP STA parameters to determine if and when which DL TX during UL TX is normal, determine if and when a trigger to a STA during UL TX is normal, and synchronize TX end times to the same STA on different links when they have different start times. As yet another example, non-AP STAs are allowed to send triggers (e.g., addressed to a single STA).

[0164] Another example is requiring the STA to synchronize the end time of any TX on a link when other links have started. Here, there is no need to check the AID or MAC address or any content of the ongoing PPDU, restrictions within the BSS (e.g., the AP indicates the required alignment in the BSS), and restrictions on PPDUs for synchronized TX STAs (e.g., a signal in the PHY header "I am a synchronized TXSTA"). Another example is additional link request signaling, which includes adding a signaling bit to request an additional link, which allows the responder to add to the response transmission to align the PPDU. Another example is next frame signaling, which allows the responder to indicate the next frame duration to force alignment.

[0165] In various aspects of the present disclosure, BSS behavior indications are provided. Here, the AP is allowed to indicate that all associated STAs that are capable of aligning transmissions align their transmissions. This is achieved by adding a signaling bit that can be transmitted within beacons and other management frames and by requiring receiving STAs that understand the operating rules to follow the rules (i.e., align transmissions on one link with transmissions on another link). The requirement can only be applied to intra-BSS PPDUs.

[0166] Fig.26The AP needs to align transmission case 2600 is shown. Section 2610 indicates that it is repeated for each link that the AP can support. For this AP needs to align transmission case 2600, the beacon transmitted by the AP contains an indication of the requirement for alignment of transmissions on various links (e.g., Link1, Link2 transmissions should be aligned). Here, the information contains the LINKID plus a mapping to indicate which links must be aligned to the link with this LINKID (e.g., bits set to "1" in the bitmap indicate those links should have aligned PPDUs), and the mapping is arranged in LINKID order.

[0167] In various aspects of the present disclosure, a synchronous STA indication PHY is provided. Here, 1 bit is added to the PHY header, Synchronous Transmitter (SYT) STA to indicate that the transmitting STA is a synchronous STA. If the STA receives a PPDU with SYT == 1, the listening receiver should align the end time of any transmission on the affected link with the end time of the transmission of this PPDU on this link, provided that they share the same BSS COLOR (i.e., non-overlapping basic service set (OBSS)). It is not necessary to align to the OBSS, but it may be preferred. In addition, an active link bit may be added to the PHY header to indicate other links that the synchronous STA has enabled (i.e., the PPDU end time of other links above should be aligned with the PPDU on this link).

[0168] Fig. 27 Example 2700 of SYT indication in the PHY header is shown. For SYT=Synchronous Transmitter STA, SYT==1 indicates that the transmitting STA is a synchronous mode STA, and SYT==0 indicates that the transmitting STA is not a synchronous mode STA. Also, the Other EHT Signal (ESIG) and More ESIG fields contain other information (e.g., MCS, length, AID, encoding, BSS color, etc.). In addition, the ESIG may also include an indication of which other links are in use by the transmitter of this PPDU (e.g., Link In Use subfield, a bitmap of links arranged in increasing frequency (FREQ) order, 1==in use, 0==not in use).

[0169] In various aspects of the present disclosure, a synchronous STA indication MAC is provided. Here, 1 bit is added to the MAC header and / or frame to indicate that the transmitting STA is a synchronous STA. If the STA receives a PPDU with SYT==1, the listening receiver should align the end time of any transmission on the affected link with the end time of the transmission of this PPDU on this link, provided that they share the same BSS COLOR (i.e., non-OBSS). It is not necessary to align to the OBSS, but it may be preferred. In addition, an active link bit may be added to the MAC header and / or frame to indicate other links that the synchronous STA has enabled (i.e., the PPDU end time of other links above should be aligned with the PPDU on this link).

[0170] Fig.28 Example 2800 of SYT indication in the MAC header is shown. For SYT=Synchronous Transmitter STA, SYT==1 indicates that the transmitting STA is a synchronous mode STA, and SYT==0 indicates that the transmitting STA is not a synchronous mode STA. And, other EHT and more ESIG fields contain other information (e.g., MCS, length, AID, encoding, BSS color, etc.). In addition, ESIG may also include an indication of which other links are in use by the transmitter of this PPDU (e.g., Link In Use subfield, bitmap of links arranged in increasing FREQ order, 1==in use, 0==not in use). A STA with an enabled link but currently in an inactive state (e.g., DOZE power saving state) should set the bit corresponding to the inactive state link to "0" to indicate that the link is not currently in use.

[0171] In various aspects of the present disclosure, TX rules are provided. For example, a STA receives an indication from its AP that TX alignment should be performed for a link with LINKID X relative to LINKID Y, as indicated by the presence of a "1" in the link Y position of the bitmap for LINKID X (e.g., align any TX PPDU on link X with any ongoing PPDU on link Y). As another example, a STA that receives an RX PPDU and a PHY header indication that the transmitter of the PPDU is a synchronized transmitter (SYT == 1) should align any TX PPDU with the ongoing RX PPDU, provided that the TX PPDU will be transmitted on the affected link, as indicated in the "Link In Use" field of the PHY header of the RX PPDU. Also, the rule may have an additional condition, namely, the BSS color of the RX PPDU must match the BSS color of the TX STA.

[0172] In various aspects of the present disclosure, other changes are provided. For example, to force TXOP sharing (e.g., all STAs), the BA receiver may be required to accept BA+QoS data instead of just BA (e.g., BA+QoS data extends the BA PPDU duration to force the start of the next RX PPDU to align). Also, for CTS negotiated DUR (e.g., EHT STA), the CTS receiver may be required to adjust the PPDU duration based on the received CTS DUR value. In addition, for the indicated RX PPDU duration (e.g., EHT STA), BA+T forces the end of the next RX PPDU to align by forcing the duration of the next RX PPDU (e.g., the T field is new information only understood by new STAs).

[0173] In various aspects of the present disclosure, trigger request conditions are provided. For example, adding two bits to the MPDU may mean requesting triggering of a specific link (e.g., a bitmap of link identification (LINKID), where "1" means triggering me in the corresponding link). As another example, adding two bits to the MPDU may mean requesting triggering of a specific AC or higher. In yet another example, a non-AP STA may be allowed to trigger another STA, where it is subject to request, limited to N==1, and the response is a SU PPDU instead of a HETB PPDU.

[0174] Fig.29 A trigger request case 2900 is shown. For TLQ = Trigger Link Request, the bitmap of the links is arranged in LINKID order, a "1" in the bitmap corresponds to a LINKID indicating a request to trigger on the link corresponding to the LINKID, and a "0" in the bitmap corresponds to a LINKID indicating a request not to trigger on the link corresponding to the LINKID. Here, TLQ AC is the requested preferred AC value for the trigger frame, TLQ MCS is the recommended MCS for the trigger PPDU, and TLQ RLEN is the length of the response to the trigger, which is optional because the receiver of the trigger should synchronize the triggered response.

[0175] In various aspects of the present disclosure, a trigger request option is provided. For example, the trigger request may be an MPDU (i.e., a complete frame with a PHY header, a MAC header, a trigger field plus optionally the AID of the STA requesting the trigger as described earlier, and a synchronization mode parameter (SMP), which is: 1) indicating the value of the noise floor at the trigger request transmitting STA on the link on which the trigger is requested, and 2) the SMP may be specified per link, since the trigger request bitmap TLQ may contain more than one trigger request for more than one link). Optionally, the AID information will need to be made available to all STAs within the BSS by the AP. The trigger request may be incorporated into an existing frame using, for example, A-Control.

[0176] In various aspects of the present disclosure, modified trigger frames and responses are provided. For example, a trigger frame or TRS is modified to allow a single user to be triggered to send a non-TB frame (e.g., any SU PPDU), as opposed to the existing response to the trigger being a HETB PPDU (i.e., an explicit indication to the trigger recipient to respond with a SU PPDU instead of a HE TB PPDU). Here, the modification may be based only on the TA of the trigger frame (i.e., if the TA of the trigger frame <> BSS identification (BSSID), then this is a trigger for a SU PPDU, not a HE TB PPDU).

[0177] In various aspects of the present disclosure, trigger and TRS modification are provided. For example, any STA is allowed to transmit a trigger / TRS in response to an RTS or as the initial PPDU of a TXOP (e.g., not just the AP is allowed to transmit a trigger). As another example, the trigger / TRS should include parameters that cause the triggered PPDU to align with another link PPDU. In yet another example, the trigger / TRS is modified to include a field indicating that the response to the trigger is a SU PPDU (e.g., rather than a HE TB PPDU). As another example, the trigger / TRS may trigger more than one user response, in which case the response will be a HE TB PPDU rather than a SU PPDU. In another example, the trigger / TRS is modified to allow the trigger receiver to select some parameters (e.g., MCS, RSSI target, spatial reuse) of the trigger response PPDU (e.g., CS is not required because the trigger is requested using RTS, so the media IDLE condition is already met). However, the PPDU duration must exist and must be used by the trigger receiver in order to align the PPDU with the PPDUs on other links.

[0178] In various aspects of the present disclosure, a next frame duration mechanism is provided. For example, signaling is added in the MAC portion of the frame to indicate the next frame duration in order to maintain alignment. This may be included in any PPDU (e.g., a bitmap containing a BA, containing QoS data, and a LinkID for which information is applied). The information may be included in a separate new MPDU constructed for this purpose, or may be included in a field within an existing frame, such as the A-Control field. The receiving STA should use this information for its next PPDU transmission on the affected link as identified in the bitmap (e.g., regardless of the destination of the PPDU). As another example, the next frame duration may be in the form of a trigger with a modified format, such as to allow a SU PPDU response to the trigger, and to allow the trigger recipient to select an MCS, including a bitmap of the LinkID for which information is applied. Here, the receiving STA should use this information for its next PPDU transmission on the affected link as identified in the bitmap, regardless of the destination of the PPDU.

[0179] In various aspects of the present disclosure, QoS data may be included in the response. For example, the BA response is allowed to increase in length to meet alignment requirements by adding QoS data or other information to increase the payload symbols and requiring the receiving STA to accept the combination rather than just the BA response.

[0180] In various aspects of the present disclosure, the TX AID may be added to the PHY header. For example, the TX AID plus "this transmitter is synced", where this is collectively a request to other STAs to avoid transmitting to the STA corresponding to the TX AID, thereby avoiding TX / RX combinations that will fail RX, and with the exchange of AID information between TDLS peers. This applies to both RX / TX and TX / RX.

[0181] In various aspects of the present disclosure, an RTS CTS exchange mechanism is provided. For example, a STA receives a CTS in response to an RTS, wherein if the CTS DUR value is less than the value expected according to the standard rule of RTS DUR-SIFS-CTS_duration, the RTS transmitter limits the duration of the PPDU after the CTS to the duration specified in the CTS, or the RTS transmitter limits the duration of the PPDU after the CTS plus the expected BA PPDU to the duration specified in the CTS. As another example, a STA receiving a CTA in response to an RTS uses the information provided in the CTA to determine the next PPDU transmission parameters and sets the next PPDU duration parameter in the next PPDU.

[0182] In various aspects of the present disclosure, a CTS zero mechanism is provided. For example, a CTS response may contain DUR==0 to indicate that no transmission should follow (i.e., RTS is rejected, or the RTS receiver is not ready to receive data PPDUs at the current time). If a CTS with DUR==0 is received, the RTS transmitter knows that there is no collision failure, there is no BER failure, and the RTS transmitter is not required to modify the CW as it would if it failed to receive the CTS. Also, the RTS transmitter should send a CF-END to cancel the NAV, or may use the reserved time to transmit to another STA.

[0183] In various aspects of the present disclosure, an RTS TA or RA value mechanism is provided. For example, the RTS TA value may be set to the MLD ADDR value of the RTS transmitter to indicate that the RTS transmitter understands the CTA frame, where the CTA may be transmitted in response to the RTS when the MLD ADDR is present in the TA field of the RTS. As another example, the RTS TA value may be set to the MLD ADDR value of the RTS receiver to indicate that the RTS transmitter understands the CTA frame, where the CTA may be transmitted in response to the RTS when the MLD ADDR is present in the RA field of the RTS.

[0184] In various aspects of the present disclosure, all discussions herein assume that the number of links involved may be greater than 2. For example, it may be necessary to perform alignment for transmissions on 3 or 4 or more links, rather than just on 2 links.

[0185] In various aspects of the present disclosure, a TX TX RTS triggering case 3000 is provided, such as Fig.30 As shown. Segment 3010 indicates that STA1 EDCA counts down to 0, and segment 3020 indicates the data PPDU. Here, the MLD AP has declared Link2 to be trigger-only, which is optional, and some STA2 are using Link2. STAw forces STA1 TX to align by sending a trigger in response to RTS (i.e., STA1 does not have the opportunity to do dual-trigger multi-link UL TX). This helps NSTR STA1 recover from deafness during LINK1 TX operation, where no deafness recovery protocol needs to be modified, but forcing alignment makes the protocol work better because the previously deaf STA is likely to work normally, i.e., what STA1 thought was IDLE is actually IDLE. Also, STAw should make the two BAs have the same length.

[0186] In various aspects of the present disclosure, a non-AP STA trigger sequence 3100 is provided, such as Fig.31 As shown. Segment 3110 indicates EDCA, and segment 3120 indicates AP TX. Here, the trigger response to RTS includes Link1 (e.g., AP DL TX to STAX) and Link2 (e.g., AP DL TX to STAY). And, STAY responds to AP RTS with a trigger aligned to DL TX (e.g., AP does not have cross-link information). In addition, STAA should attempt to align BA, where STAA can include a trigger in the data PPDU for non-cross-link APs.

[0187] In various aspects of the present disclosure, an expected interference trigger case 3200 is provided, such as Fig.32As shown. Segment 3210 indicates that STA1 EDCA counts down to 0, segment 3220 indicates data PPDU, and segment 3230 indicates that the receiver expects future internal / local interference events. Here, STAw knows the upcoming local / internal interference / resource issues (e.g., time periods for antenna sharing with other communication technologies, time periods sensitive to other communication technologies, channel switching for scheduled P2P exchanges, or other scheduled non-existence events). And, the trigger request DATA phase will operate within the constraints of the upcoming interference / commitment. This is not limited to MLD, and it can be used for single-link devices. For some scenarios, BA transmission may occur during local events. And, the trigger may specify separate RX and TX completion deadlines and subsequent interference end times.

[0188] In various aspects of the present disclosure, additional uses of the triggered SU PPDU are provided. For example, for polled UL triggering (e.g., AP obtains access and lends TXOP to selected STA). Here, various parameters of UL TX can be kept as options for the triggered STA (e.g., length, MCS, number of spatial streams (NSS), etc.). As another example, for use in P2P exchanges (e.g., when an AP obtains TXOP and lends it to a STA for P2P use, when one peer has intermittent availability, the trigger is effectively a notification of availability. Again, various parameters of UL TX can be kept as options for the triggered STA (e.g., length, MCS, NSS, etc.).

[0189] In aspects of the present disclosure, in some cases, the STA transmitting the trigger may specify some strict parameters, and the exact value is kept as an option for the triggered STA or some parameters within a range of values.

[0190] In various aspects of the present disclosure, trigger-only link restrictions are provided. For example, if the AP has declared LinkB as trigger-only (e.g., the AP does not have to deal with MyBSS contention), the probability of being able to transmit a trigger on more than one link is enhanced. The limitations of trigger-only links are: 1) it reduces the ability of any STA to obtain the lowest latency UL access (i.e., a non-AP STA cannot obtain the latency advantage of having multiple links on which to contend for access when it is not allowed to contend for more than one link), and 2) if the non-AP STA is allowed to contend on the triggered link (when it is not in use), the latency performance can be restored, as seen in the trigger-limited link definition below. Trigger-limited links include trigger-only restrictions that only apply until one link is occupied, wherein when only one link is occupied, the trigger restrictions are relaxed to allow EDCA to access the unoccupied trigger-limited link. The condition is that the winner of the TXOP on the trigger-limited link performs alignment with the occupied link. Here, EDCA access is delayed until it is known whether both links will be triggered (e.g., triggering EDCA access on the restricted link starts P interframe spaces (PIFS) after the start of the triggered PPDU on the occupied link, when the triggering aligned PPDU would have occurred but has not yet occurred).

[0191] In various aspects of the present disclosure, a comparison with waiting slots is provided. For waiting slots, 1) a synchronization (also called NSTR) STA optionally maintains a link's backoff count at or near zero to wait for another link's backoff to reach zero, 2) simultaneous aligned PPDU transmissions on multiple links are achieved, 3) indicating that the probability of acquiring more than one link decreases rapidly as load increases, and 4) in the case of misalignment, as load increases, the winning NSTR transmitter is effectively penalized after each transmission, waiting to realign on the deaf channel (e.g., losing the latency benefit of having multiple channels). Here, the RTS triggering method with triggered restricted access rules allows multi-link access to be acquired under higher load conditions, where the enforcement of PPDU alignment makes operation more efficient for small contending node counts (e.g., recovering latency benefits). And, the centralized decision on the number of links occupied by NSTR contenders allows centralized decisions on the tradeoff between throughput and latency.

[0192] In various aspects of the present disclosure, the following rules may be included in the description of media access: 1) there will be a trigger message that can be transmitted by the AP or non-AP STA and trigger a SU PPDU, 2) there will be a frame exchange sequence that allows triggered frame transmission in response to receiving an RTS, and 3) the AP can indicate that the link is trigger-limited so that UL access on the link is limited to triggered access, with the exception that i) if the PPDU is transmitted on a non-trigger-limited link, then EDCA access can be performed on the trigger-limited link when the PPDU has a PHY LENGTH indication >= 0.50ms after the start of the PPDU on the non-trigger-limited link, and ii) any PPDU transmitted by a non-AP STA on the trigger-limited link will terminate at or before the end of the aligned PPDU on the other link.

[0193] Embodiments of the scope of the present disclosure may be implemented in part or in whole using a tangible computer-readable storage medium (or multiple tangible computer-readable storage media of one or more types) encoding one or more instructions. The tangible computer-readable storage medium may also be non-transitory in nature.

[0194] Computer-readable storage media can be any storage media that can be read, written, or otherwise accessed by a general or special purpose computing device (which includes any processing electronics and / or processing circuits capable of executing instructions). For example, but not limitation, computer-readable media can include any volatile semiconductor memory, such as RAM, DRAM, SRAM, T-RAM, Z-RAM, and TTRAM. Computer-readable media can also include any non-volatile semiconductor memory, such as ROM, PROM, EPROM, EEPROM, NVRAM, flash memory, nvSRAM, FeRAM, FeTRAM, MRAM, PRAM, CBRAM, SONOS, RRAM, NRAM, particle track memory, FJG, and millipede memory.

[0195] Furthermore, the computer-readable storage medium may include any non-semiconductor memory, such as optical disk storage, magnetic disk storage, magnetic tape, other magnetic storage devices, or any other medium capable of storing one or more instructions. In some implementations, the tangible computer-readable storage medium may be directly coupled to the computing device, while in other implementations, the tangible computer-readable storage medium may be indirectly coupled to the computing device, for example, via one or more wired connections, one or more wireless connections, or any combination thereof.

[0196] Instructions may be directly executable or may be used to develop executable instructions. For example, instructions may be implemented as executable or non-executable machine code, or as instructions in a high-level language that can be compiled to produce executable or non-executable machine code. In addition, instructions may also be implemented as or may include data. Computer executable instructions may also be organized in any format, including routines, subroutines, programs, data structures, objects, modules, applications, applets, functions, etc. As recognized by those skilled in the art, details including but not limited to the number, structure, sequence, and organization of instructions may vary significantly without changing the underlying logic, functionality, processing, and output.

[0197] Although the above discussion primarily relates to microprocessors or multi-core processors that execute software, one or more implementations are performed by one or more integrated circuits, such as application specific integrated circuits (ASICs) or field programmable gate arrays (FPGAs). In one or more implementations, such integrated circuits execute instructions stored on the circuits themselves.

[0198] The previous description is provided to enable those skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applicable to other aspects. Therefore, the claims are not intended to be limited to the aspects shown herein, but will be given a full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean "there is and only one" (unless explicitly stated), but rather "one or more". Unless otherwise specifically stated, the term "some" refers to one or more. Pronouns for males (e.g., his) include females and neutral genders (e.g., her and its), and vice versa. Titles and subtitles, if present, are used only for convenience and do not limit the present disclosure.

[0199] The assertions "configured to," "operable to," and "programmed to" do not imply any specific tangible or intangible modification of the subject matter, but are intended to be used interchangeably. For example, a processor configured to monitor and control an operation or component may also mean that the processor is programmed to monitor and control the operation, or that the processor is operable to monitor and control the operation. Likewise, a processor configured to execute code may be understood to be a processor programmed to execute code or operable to execute code.

[0200] Phrases such as "aspects" do not imply that such aspects are essential to the present invention or that such aspects apply to all configurations of the present invention. Disclosures related to aspects may apply to all configurations, or one or more configurations. Phrases such as "on one hand" may refer to one or more aspects and vice versa. Phrases such as "configuration" do not imply that such configurations are essential to the present invention or that such configurations apply to all configurations of the present invention. Disclosures related to a configuration may apply to all configurations, or one or more configurations. Phrases such as "configuration" may refer to one or more configurations and vice versa.

[0201] The word “example” is used herein to mean “serving as an example or illustration.” Any aspect or design described herein as an “example” is not necessarily to be construed as preferred or advantageous over other aspects or designs.

[0202] All structural and functional equivalents of the elements of the various aspects described throughout this disclosure that are known or will become known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be covered by the appended claims. In addition, nothing disclosed herein is intended to be dedicated to the public, regardless of whether the disclosure is explicitly stated in the claims. Claim elements should not be interpreted under the terms of Chapter VI of 35 U.S.C. § 112 unless the element is explicitly described using the phrase "component for..." or, in the case of a method claim, the element is described using the phrase "step for..." In addition, to the extent that the terms "including," "having," or similar terms are used in the specification or claims, such terms are intended to be inclusive in a manner similar to the term "including," as explained when "including" is used as a transitional word in the claims.

[0203] Those skilled in the art will appreciate that the various illustrative blocks, modules, elements, components, methods, and algorithms described herein may be implemented as electronic hardware, computer software, or a combination of both. To illustrate this interchangeability of hardware and software, various illustrative blocks, modules, elements, components, methods, and algorithms have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. Those skilled in the art may implement the described functionality in different ways for each specific application. The various components and blocks may be arranged in different ways (e.g., arranged in different orders, or partitioned in different ways) without departing from the scope of the present invention.

Claims

1. A method comprising: Initiating transmission of a first data unit on a first wireless link of a first multi-link device; requesting, using a request frame on the first wireless link, that a trigger from a second multi-link device be transmitted on either or both of the first wireless link and the second wireless link, or on neither the first wireless link nor the second wireless link; as well as aligning a last symbol end time of a response transmission on the second wireless link with a last symbol end time of a response transmission on the first wireless link in response to receiving a trigger on both the first wireless link and the second wireless link; characterised in that if the first multi-link device initiates transmission of the first data unit on the first radio link during an ongoing transmission on the second radio link, triggering a response to the request frame to be aligned to a response to the ongoing transmission by checking trigger information from the ongoing transmission and using the trigger information to determine a length of the response transmission on the second radio link.

2. The method of claim 1, wherein the trigger comprises an uplink length field value.

3. The method of claim 1, wherein the trigger causes a single user physical layer protocol data unit.

4. The method of claim 1, wherein the trigger causes an efficient trigger-based physical layer protocol data unit. The method of claim 1 , wherein the second multi-link device is a non-access point multi-link device. The method of claim 1 , wherein the trigger is a TRS type trigger. The method according to claim 1 , wherein the request frame is a sending request frame or a trigger request frame.

8. An apparatus adapted to perform the method according to any one of claims 1 to 7.

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