Channel Access on Non-Concurrent Transmit / Receive Links

Abstract

A wireless communication protocol in which multilink operation increases efficiency, especially in non-simultaneous transmit / receive (NSTR) communication between stations (STAs) of a multilink device (MLD). When MLD1 is the TXOP owner on link 1 and MLD2 accesses the channel on link 2 to transmit to MLD1, if MLD1 is receiving on link 1, MLD2 immediately transmits to MLD1 via link 2. If MLD1 is transmitting on link 1, MLD2 transmits a frame via link 2 to seize the channel, and then, while MLD1 is receiving on link 1, MLD2 transmits another frame to MLD1.

Description

Technical Field

[0001] [Cross - Reference to Related Applications] This application claims priority and the benefit thereof to U.S. Patent Application Serial No. 17 / 847,342, filed on June 23, 2022, which is hereby incorporated by reference in its entirety. This application also claims priority and the benefit thereof to U.S. Provisional Patent Application Serial No. 63 / 223,634, filed on July 20, 2021, which is hereby incorporated by reference in its entirety.

[0002] [Description of Research or Development Sponsored by the Federal Government] Not applicable

[0003] [Notice of Materials Subject to Copyright Protection] Some of the materials in this patent document may be subject to copyright protection under the copyright laws of the United States of America and other countries. The copyright owner does not object to the reproduction of the patent document or patent disclosure by a third party as represented in the public files or records of the United States Patent and Trademark Office, but reserves all copyrights otherwise. The copyright owner does not hereby waive any of its rights to keep this patent document confidential, including, without limitation, rights under 37 C.F.R. § 1.14.

[0004] The technology of this disclosure generally relates to wireless local area networks (WLANs) that use carrier sense multiple access / collision avoidance (CSMA / CA) for channel access, and more specifically, to obtaining channel access rights for stations of non - simultaneous transmit / receive (NSTR) multi - link devices (MLDs).

Background Art

[0005] Current wireless technologies using CSMA / CA focus on high throughput performance of the network but lack sufficient low latency capabilities. Therefore, there is a technology gap because an increasing number of applications, including real-time applications (RTA), require low latency communication capabilities.

[0006] RTA requires low latency communication and uses best-effort communication. Data generated from RTA is called RTA traffic and is packetized as RTA packets at the transmitting STA. On the other hand, data generated from non-time-dependent applications is called non-RTA traffic and is packetized as non-RTA packets at the transmitting STA.

[0007] RTA packets require low latency due to the high timeliness requirement for packet delivery. RTA packets are only valid if they are delivered within a certain time.

[0008] Among the local STAs, some can perform STR as simultaneous transmit and receive (STR) STAs, while others called non-STR STAs cannot perform transmission and reception simultaneously, making these problems even more complex. Summary of the Invention Problems to be Solved by the Invention

[0009] Therefore, a WLAN CSMA / CA protocol that can support RTA communication for both STR STAs and non-STR STAs is needed. The present disclosure provides further advantages while overcoming these problems. Means for Solving the Problems

[0010] A wireless local area network (WLAN) operating under an IEEE 802.11 protocol such as 802.11be that uses carrier sense multiple access / collision avoidance (CSMA / CA) enables a non-simultaneous transmit / receive (NSTR) station (STA) to occupy a channel even when the NSTR STA cannot transmit immediately after acquiring channel access rights. In this protocol, even when the transmit opportunity (TXOP) owners on two links are from different multi-link devices (MLDs), the associated MLDs schedule transmissions over the links simultaneously.

[0011] In the following parts of this specification, further aspects of the techniques described herein will become apparent, and this detailed description is for the purpose of fully disclosing the present technology without limiting the preferred embodiments of the present technology.

[0012] The techniques described herein will be fully understood by reference to the following drawings, which are for illustrative purposes only.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

Figure 23

Figure 24

Figure 25

Figure 26

Figure 27

Figure 28

Figure 29

Figure 30

Figure 31

Figure 32

Figure 33

Figure 34

Figure 35

Figure 36

Figure 37

DETAILED DESCRIPTION OF THE INVENTION

[0014] 1. WLAN Overview 1.1 CSMA / CA WLAN System In a WLAN system, IEEE 802.11 uses Carrier Sense Multiple Access / Collision Avoidance (CSMA / CA) to enable STAs to access the channel for packet transmission and retransmission.

[0015] Figure 1 shows the CSMA / CA channel access process. In a CSMA / CA system, before each transmission and retransmission, the STA needs to sense the channel and set a backoff time to compete for channel access rights. The backoff time is determined by a uniform random variable between zero and the size of the contention window. The STA senses that the channel is idle during contention and decrements the backoff time. When the backoff reaches zero, the STA has acquired the channel for packet transmission. If the STA does not receive an acknowledgment (ACK) before the expiration of the timeout interval, retransmission may be required. Otherwise, the transmission is successful.

[0016] If retransmission is required, the STA checks the number of retransmissions of the packet. If the number of retransmissions exceeds the retry limit, the packet is discarded and retransmission is not scheduled. Otherwise, retransmission is scheduled.

[0017] Before executing retransmission, another backoff time is required to compete for channel access rights. If the size of the contention window (CW) has not reached the upper limit of the CW size, the STA increases the CW size. The STA sets another backoff time according to the new size of the contention window. The STA waits for the backoff time for retransmission and continues this until normal transmission or retransmission is achieved.

[0018] Figure 2 shows the data frame format in a normal WLAN system. The Frame Control field indicates the type of the frame. The Duration field contains the NAV information used for CSMA / CA channel access. The RA field contains the address of the recipient of the frame. The TA field contains the address of the STA that transmitted the frame. The Sequence control field contains the fragment number and sequence number of the packet.

[0019] Figure 3 shows the format of an ACK frame in a normal WLAN system. The Frame Control field indicates the type of the frame. The Duration field contains the NAV information used for CSMA / CA channel access. The RA field contains the address of the recipient of the frame.

[0020] Figure 4 shows the format of a High Efficiency (HE) Single User (SU) Physical Layer Protocol Data Unit (PPDU) used for transmission in IEEE 802.11ax. Note that the PPDU includes at least a preamble field and a data field, and in at least one embodiment has the following fields. The L-STF field is a non-High Throughput (non-HT) short training field. The L-LTF field is a non-HT long training field. The L-SIG field is a non-HT signal field. The RL-SIG field is a repeating non-HT signal field. The HE-SIG-A field is a HE signal A field. The HE-STF field is a HE short training field. The HE-LTF field is a HE long training field. The Data field carries the data of the Physical Layer Convergence Procedure (PLCP) Protocol Data Unit, which is called the Physical Service Data Unit (PSDU). The PE field is a packet extension field.

[0021] Figure 5 shows an example of retransmission in CSMA / CA where the backoff time increases due to retransmission. The data frame and the ACK frame use the formats shown in FIGS. 2 and 3, respectively. These frames are packetized using the packet format shown in FIG. 4. After the transmitting side performs the first packet transmission, it does not receive an ACK by the timeout. As a result, the transmitting side sets another backoff time with the size of the contention window being "n" slots. The transmitting STA retransmits the packet only after waiting for the backoff time. However, in this example, this retransmission also fails. The transmitting STA sets the backoff time again to compete for the channel access right for packet retransmission. However, this time, due to the retransmission, the size of the contention window is 2*n slots, which is twice as large. The expected backoff time also doubles due to this contention window size. The second retransmission is successful because an ACK is received before the timeout.

[0022] Figure 6 shows an example where a packet is discarded after the number of retransmissions exceeds the retry limit. In this example, the retry limit is indicated by "R". The data frame and the ACK frame use the formats shown in FIGS. 2 and 3, respectively. These frames are packetized using the packet format shown in FIG. 4. As shown in FIG. 6, after the transmitting STA fails in the first packet transmission, it retransmits this packet a plurality of times. However, none of the retransmissions are successful. After R retransmissions, the number of retransmissions exceeds the retry limit, and the transmitting STA stops retransmitting the packet, and this packet is discarded.

[0023] 1.2. EDCA System Figure 7 shows a reference model of an (Extended Distributed Channel Access) EDCA queue in IEEE 802.11. The system includes six transmit queues and four access categories (ACs). Each AC competes for the channel access right using the EDCA function (EDCAF) to be able to transmit the packets in the corresponding transmit queue.

[0024] The six transmission queues are Voice (VO), Alternative Voice (A_VO), Alternative Video (A_VI), Video (VI), Best Effort (BE), and Background (BK). Each transmission queue determines the transmission order of the packets within the queue.

[0025] The four ACs are Voice (VO), Video (VI), Best Effort (BE), and Background (BK). Each AC has an Enhanced Distributed Channel Access Function (EDCAF) that provides the function of channel contention. When multiple EDCAFs attempt to access the channel simultaneously, an internal collision avoidance mechanism is used. If an internal collision occurs, the EDCAF with a higher priority acquires the channel access right.

[0026] Table 1 lists the UP-to-AC mapping used in the EDCA queues of IEEE 802.11. The second and third columns represent the user priority of the traffic and its corresponding designation in IEEE 802.1D. In each row, according to the user priority, the traffic is added to the corresponding transmission queue and access category. The priority increases from the top row to the bottom row. The higher the priority of the traffic, the higher the probability of being transmitted earlier.

[0027] Figure 8 shows the channel access procedure of EDCA. As shown in the figure, the EDCA channel access when only the Distributed Coordination Function (DCF) is used is also compared.

[0028] When using only DCF, the STA can immediately access the channel, and the medium is free for a period longer than the DCF Inter-Frame Space (DIFS) time. Otherwise, the STA uses CSMA / CA to compete for access to the channel. After detecting that the channel is idle for the DIFS time, the STA starts counting down the backoff as long as the medium is idle. The number of backoff slots is randomly selected between zero and the contention window. When the STA senses that CCA busy (or medium busy) occurs, e.g., the channel is busy, it pauses the backoff countdown. When the backoff count reaches zero, the STA starts transmitting the packet.

[0029] In EDCA, when the medium is free for a period longer than the DIFS time or for the Arbitration Inter-Frame Spacing (AIFS) time required to acquire the channel access right for the AC, each EDCAF as shown in FIG. 7 can immediately access the channel. Note that AIFS[i] shown in the figure represents the AIFS time of AC i. Otherwise, each EDCAF uses CSMA / CA to compete for the channel for each AC that intends to acquire the channel access right. After detecting that the channel is idle for the AIFS time, each EDCAF starts counting down the backoff while the medium is idle. The number of backoff slots to be counted down is randomly selected between zero and its contention window size. When the STA senses that CCA busy (or medium busy) occurs, i.e., the channel is detected to be busy, it pauses the backoff countdown. When the backoff is counted down to zero, the STA starts transmitting the packet for that AC.

[0030] Note that multiple EDCAs can also compete for channels simultaneously. For example, as shown in FIG. 8, the EDCA of AC i and the EDCA of AC j can compete for channels simultaneously. When an internal collision occurs, the EDCA with a higher priority acquires the channel access right, and the EDCA with a lower priority doubles its contention window. When the AC is VO or VI, they can reserve a non-competing period such as TXOP to transmit packets. The maximum duration of TXOP is called TXOP limit.

[0031] Table 2 shows the default parameter settings for EDCA channel access. Each AC has its own minimum contention window and maximum contention window. AIFSN represents the AIFS period in units of backoff slots. TXOP limit represents the maximum duration of TXOP that each AC can reserve each time.

[0032] 1.3.A - Control Subfield Variants of the Control Subfield FIG. 9 shows the HT control field format of the A - control subfield variant defined in IEEE802.11ax. The Format indication field is used to indicate the format of the HT control field. When bits B0 and B1 are set to 1, this field indicates that the HT control field uses the HE / EHT format. After this field, there is an A - Control field. The A - Control field carries different types of buffer status reports. The Control ID field indicates the type of the control information subfield. For example, when this bit is set to the value "3", the control information field carries BSR information. The control information field carries the control information indicated by the Control ID field.

[0033] FIG. 10 shows the control information subfield format when the control ID field in FIG. 9 indicates that the control information is for BSR.

[0034] FIG. 11 shows a control information subfield format when the control ID field of FIG. 9 indicates that the control information is for the CAS.

[0035] 2. Description of the Problem MLDs can provide the ability of Simultaneous Transmit and Receive (STR). Since these MLDs have low in-device coexistence interference, they can perform reception on any other link while transmitting on one link at the same time. However, non-STR (NSTR) MLDs cannot safely perform these simultaneous transmissions and receptions. However, both STAs of STR-MLD or non-STR MLD can perform simultaneous transmission or reception.

[0036] This disclosure considers channel contention executed via an NSTR link pair by a multi-link device (MLD) using CSMA / CA. In an MLD with high in-device coexistence interference between links of an NSTR link pair, for example, interference caused by an STA of the MLD transmitting a signal on one link of the NSTR link pair may interfere with or prevent another STA of the same MLD from receiving a signal on the other link of the NSTR link pair. Therefore, the MLD should not perform transmission on the other link of the same NSTR link pair while performing reception on one link of the NSTR link pair.

[0037] FIG. 12 shows problems that may occur when an STR MLD communicates with an NSTR MLD via an NSTR link pair of the NSTR MLD. An example of this scenario will be described in a later section. MLD1 is an NSTR MLD, and Link 1 and Link 2 are one NSTR link pair of MLD1.

[0038] Referring to FIG. 12, when STA1 belonging to MLD1 is the TXOP owner on Link 1 and STA4 belonging to MLD2 acquires the channel access right for transmission to STA2 on Link 2, there may be a problem. STA3 can monitor the state of STA1 by determining that STA1 is the TXOP owner on Link 1, for example, determining whether STA1 is transmitting or receiving. If STA1 is transmitting and STA4 immediately accesses the channel to transmit to STA2, there may be a transmission collision due to in-device coexistence interference between the NSTR links. If STA4 does not immediately access the channel, it can no longer access the channel after STA1 finishes transmitting on Link 1. The simplest solution is to prohibit STA4 from accessing the channel on Link 2. However, this conventional technique reduces the transmission efficiency. Therefore, the teachings of the present disclosure enable a non-STR MLD STA (e.g., STA4) to access the channel and communicate with STA2, resulting in an increase in bandwidth, an improvement in throughput, and a reduction in latency. However, there may be problems in this process even with a simple implementation.

[0039] Specifically, there is a problem in the method by which STA4 notifies STA2 or MLD1 that it is the TXOP owner of Link 2. STA4 needs to occupy the channel immediately after accessing the channel. However, when STA4 accesses the channel, STA1 may be transmitting on Link 1. At this time, MLD1 (i.e., STA2 belonging to MLD1) cannot receive communication from STA4.

[0040] Since the TXOP owners are different on Link 1 and Link 2, in-device coexistence interference (IDC) may often occur when the transmission directions of the two links are different. Therefore, the present disclosure will describe the process of arranging transmissions on Link 1 and Link 2.

[0041] 3. Contribution of the Present Disclosure The present disclosure teaches a protocol (apparatus / method) that enables a non-STR MLD's STA (e.g., STA4) to occupy a channel even when transmission (e.g., to STA2) is not permitted immediately after obtaining channel access rights (e.g., on link 2).

[0042] The disclosed CSMA / CA WLAN protocol enables any one of the MLDs (e.g., MLD1 or MLD2) to schedule transmissions over two links simultaneously, even though the TXOP owners on the two links are from different MLDs.

[0043] 4. Hardware Embodiments 4.1. Hardware Configuration of STA and MLD FIG. 13 shows an example embodiment 10 of STA hardware configured to execute the protocol of the present disclosure. An external I / O connection 14 is coupled to an internal bus 16 of the circuit 12, and preferably, a CPU 18 and a memory (e.g., RAM) 20 are connected on the internal bus 16 to execute a (single or multiple) program implementing a communication protocol. The host machine houses at least one modem 22 that supports communication, coupled to at least one RF module 24, 28, each of which is connected to one or more antennas 29, 26a, 26b, 26c - 26n. An RF module having a plurality of antennas (e.g., an antenna array) enables beamforming to be performed during transmission and reception. Thus, the STA can transmit signals using multiple sets of beam patterns.

[0044] Bus 14 can connect various devices such as sensors and actuators to the CPU. On processor 18, instructions from memory 20 are executed to run a program that implements a communication protocol to enable the STA to perform the functions of an access point (AP) station or a normal station (non-AP STA). Also, this programming is configured to operate in different modes (TXOP owner, TXOP shared participant, source, intermediate, destination, first AP, other AP, station related to the first AP, station related to other APs, coordinator, coordinatee, AP within OBSS, and STA within OBSS, etc.) depending on what role it is playing in the current communication situation.

[0045] Accordingly, the illustrated STA HW is composed of at least one modem and associated RF circuitry for providing communication in at least one band. This disclosure is mainly targeted at the sub-6 GHz band.

[0046] It should be understood that this disclosure can be configured using a plurality of modems 22 each coupled to any number of RF circuits. Generally, the more RF circuits used, the wider the coverage of the antenna beam direction. It should be understood that the number of RF circuits and antennas used is determined by the hardware constraints of a particular device. Some of the RF circuits and antennas can be disabled when the STA determines that it does not need to communicate with neighboring STAs. In at least one embodiment, the RF circuitry includes a frequency converter and an array antenna controller, etc., and is connected to a plurality of antennas controlled to perform beamforming for transmission and reception. In this way, the STA can transmit signals using a set of multiple beam patterns where each beam pattern direction is considered an antenna sector.

[0047] Also, multiple instances of the station hardware as illustrated can be combined into a multi-link device (MLD), which typically has a processor and memory to coordinate the activities of the stations.

[0048] Figure 14 shows an example embodiment 40 of the hardware configuration of a multi-link device (MLD). The MLD has two links known as a primary link and a conditional link. The conditional link is a link that forms a non-simultaneous transmission / reception (NSTR) link pair together with several basic links.

[0049] A plurality of STAs belong to the MLD, and each STA operates on a link with a different frequency. The MLD has external I / O access to an application, and this access connects to an MLD management entity 48 having a CPU 62 and a memory (e.g., RAM) 64, enabling the execution of a (single or multiple) program that implements a communication protocol at the MLD level. The MLD can here distribute tasks to each of the connected stations exemplified as STA1 42, STA2 44 to STA N 46 and collect information from them, and share information among the belonging STAs.

[0050] In at least one embodiment, each STA of the MLD has its own CPU 50 and memory (RAM) 52, which are coupled through a bus 58 to at least one modem 54 connected to at least one RF circuit 56 having one or more antennas. In this example, the RF circuit has a plurality of antennas 60a, 60b, 60c to 60n in the form of an antenna array. The modem combined with the RF circuit and the associated (single or multiple) antennas transmits / receives data frames to / from neighboring STAs. In at least one implementation, the RF module includes a frequency converter, an array antenna controller, and other circuits for interlocking with its antennas.

[0051] It should be understood that each STA of the MLD can share resources with each other and / or with the MLD management entity according to a specific MLD implementation, and thus does not necessarily require its own processor and memory. Note that the above MLD diagram is shown as an example and not a limitation, and it should be understood that the present disclosure can operate with a wide range of MLD implementations.

[0052] 4.2 STA Topology of Usage Example FIG. 15 shows an embodiment 70 of a network topology example used to explain the purpose of the present disclosure. Note that since the apparatus and method of the present disclosure are not limited to a specific topology, this topology (and all topologies exemplified in this specification) should be understood as an example rather than a limitation. Also, the specific MLD, STA, and links referred to throughout the present disclosure are merely shown to simplify the understanding of the operation. Note that Link 1 and Link 2 are one NSTR link pair of MLD1.

[0053] A multi-link device (MLD) is a device having a plurality (usually two) of affiliated STAs and one MAC service access point (SAP) to a logical link control (LLC) including one MAC data service. When the STA of the MLD is an AP STA, the MLD is regarded as an AP MLD, while when a non-AP STA belongs to the MLD, the MLD is a non-AP MLD.

[0054] As shown in the example figure, assume that these STAs on two MLDs 74, 76 exist within a structure 72 such as a conference room. STA1 78 and STA2 80 belong to MLD1, and STA3 82 and STA4 84 belong to MLD2. STA1 and STA2 are associated with STA3 and STA4 via Link 1 86 and Link 2 88, respectively.

[0055] In some cases, as illustrated in the demonstration of the operation of the present disclosure in such an NSTR situation, link 1 and link 2 will be recognized as an NSTR link pair such as MLD1. Note that all STAs use CSMA / CA for random channel access on all links. In this specific topology example, MLD1 is regarded as an NSTR MLD and MLD2 is regarded as an STR MLD. Link 1 and link 2 are one NSTR link pair of MLD1. STA1 communicates with STA3 via link 1, and STA2 communicates with STA4 via link 2. The network topology as shown can represent two scenarios: (a) a scenario where MLD2 is an STR AP MLD and MLD1 is an NSTR non-AP MLD, or (b) a scenario where MLD1 is a soft AP and MLD2 is an STR non-AP MLD.

[0056] Note that the term "soft AP" is an abbreviation for "software-enabled access point" or "NSTR mobile AP MLD", where the local hardware can be the same as a normal (non-AP) STA, but software enables the STA to be an AP.

[0057] In the illustrated network topology, since STA3 belonging to MLD2 is transmitting or receiving with STA1 on link 1, it is assumed that MLD2 can determine the transmission and reception status of STA1 on link 1. Also, MLD2 can share the status information of STA1 on link 1 with STA4 belonging to it on link 2.

[0058] 4.3. Channel Access on NSTR Links In this section, a method for STA4 to access the channel on link 2 when STA1 is the TXOP owner of link 1 will be described. Note that to simplify the description, the network topology shown in FIG. 15 is used in the flowchart and communication example.

[0059] 4.3.1. Channel Access Process FIG. 16 shows an example embodiment 90 of channel access by STA4 on link 2 when STA1 is transmitting on link 1.

[0060] When STA1 belonging to MLD1 is transmitting on link 1 (92), STA4 belonging to MLD2 accesses the channel on link 2 and communicates with STA2 belonging to MLD1.

[0061] When link 1 and link 2 are an NSTR link pair of MLD1, STA2 may not be able to receive (sense) from STA4 on link 2 when STA1 is transmitting on link 1. Therefore, in block 94, STA4 transmits a dummy frame such as a short frame not containing a data packet to STA2 in order to reserve the TXOP period on link 2. Note that STA4 can also broadcast the dummy frame. The dummy frame can be created in many forms such as, for example, a request to send (RTS), a multi-user RTS (MU-RTS), a MU-RTS TXOP sharing (TXS) frame, a clear to send (CTS), a CTS-to-Self frame, or other sharing frames as shown in FIG. 23. The reserved TXOP time required by the dummy frame occupies the channel until STA2 can receive from STA4 on link 2, and then STA4 can immediately transmit a frame to STA2.

[0062] In check 96, it is determined whether there is an opportunity (chance) for STA4 to transmit to STA2 before the TXOP reserved by the dummy frame ends (for example, whether STA2 is receiving). If the condition is satisfied, STA4 transmits a packet to STA2 (98).

[0063] Otherwise, STA4 does not send a packet to STA2 (100). As a result, STA4 can immediately start a new backoff, or in some cases, does not start a new backoff until the end of STA1's TXOP, or can start a new backoff when it has packets to send to other STAs, or maintains the backoff count at 0.

[0064] 4.3.2. Link Access Examples In this section, multiple examples are shown where STA4 accesses the channel on Link 2 when STA1 is the TXOP owner on Link 1. This broadens the channel communication bandwidth between the MLDs (MLD1 and MLD2), resulting in improved throughput and reduced latency. Note that the PPDU (from STA4 to STA2) shown in the examples of this section can include an NSTRCrd Request / Indication frame (such as those shown in FIGS. 32 to 34), or a PPDU for starting NSTR coordination where RDG = 1 and the NSTR coordination indication is set to the first state (e.g., "1") as shown in Section 4.4.

[0065] In the examples shown in this section, it is assumed that since STA3 belonging to MLD2 is transmitting or receiving with STA1 on Link 1, MLD2 can determine the transmission and reception status of STA1 on Link 1. Also, MLD2 shares the status information of STA1 on Link 1 with STA4 belonging to it on Link 2.

[0066] FIG. 17 shows Embodiment Example 110 where STA4 reserves a TXOP on Link 2 using a dummy frame. This figure shows MLD2 76 having related STAs 3 82 and STA4 84 communicating with MLD1 74 having related STAs 1 78 and STA2 80.

[0067] STA1 acquires TXOP112 on Link 1 and starts transmission 114 to STA3 on Link 1. Next, while STA1 is transmitting on Link 1, STA4 acquires channel access rights for transmission to STA2. STA4 transmits a dummy frame 116 to reserve a short-term TXOP. STA1 completes its own transmission before the reserved short-term TXOP ends and starts reception 118 from STA3 via Link 1. When STA1 is receiving, STA4 can transmit (single or multiple) PPDUs 120 to STA2 in a state where it is guaranteed that the reception at STA2 is not blocked by in-device coexistence interference.

[0068] Note that PPDU alignment between two links may not be necessary, but the directions of PPDU transmission on the two links should be the same. In other words, the directions of PPDU transmission on the two links should both be UL or both be DL at the same time. The transmission information (preamble and MAC header of the PPDU) on Link 1 can assist STA4 in transmitting a PPDU (from STA4 to STA2) when STA1 is receiving.

[0069] STA4 may need to perform carrier sensing (CS) to detect the channel state during the time between the dummy frame on Link 2 and the PPDU from STA4 to STA2. If the channel becomes busy during this time, STA4 cannot transmit a PPDU from STA4 to STA2 and can start a new channel contention.

[0070] Note that MLD2 is STR MLD. Therefore, STA4 can start and end PPDU transmission to STA2 (which can include multiple PPDUs, for example) during the time when STA4 is receiving on Link 1.

[0071] FIG. 18 shows Embodiment Example 130 in which STA4 reserves a TXOP on Link 2 using a dummy frame, but there is no opportunity to transmit to STA2 during the reserved TXOP. In this case, STA1 is sequentially transmitting a plurality of PPDUs during transmission on Link 1. The MLD, STA, and Link are the same as those in FIG. 17.

[0072] Here too, it can be seen that STA1 acquires a TXOP and starts transmission 114 to STA3 (112). Next, while STA1 is transmitting on Link 1, STA4 acquires the channel access right to Link 2 for transmission to STA2 and transmits a dummy frame to reserve a short-term TXOP (116). Within the reserved short-term TXOP 132, STA1 is still transmitting on Link 1, and thus STA4 cannot transmit a PPDU that can be sensed by STA2 to STA2. Therefore, STA4 does not transmit a PPDU to STA2 during the short-term TXOP and fails to access the channel.

[0073] STA4 can re-contend for the channel after the short-term TXOP. In this case, in at least one embodiment / mode / case, STA4 continues to access the channel without increasing the contention window (CW) for the channel.

[0074] FIG. 19 shows Embodiment Example 150 in which STA4 occupies the channel on Link 2 using a dummy frame. The MLD, STA, and Link are the same as those shown in FIG. 18.

[0075] Here too, it can be seen that STA1 acquires a TXOP and starts transmission 114 to STA3 (112). Next, while STA1 is transmitting on Link 1, STA4 acquires the channel access right to Link 2 for transmission to STA2 and transmits a dummy frame to occupy the channel for transmission to STA2 (152).

[0076] In this example, STA4 makes the end time of the dummy frame 152 coincide with the end time of STA1's transmission. The reason for this is that STA4 can determine the time when STA1 finishes transmitting based on the PPDU length information from STA3, etc. The dummy frame can include padding within the frame to achieve alignment.

[0077] After STA1 finishes transmitting on Link 1 and starts receiving 154, STA4 can transmit a PPDU (or multiple PPDUs) 156 to STA2, and it is guaranteed that there is no in-device coexistence interference that prevents STA2 from sensing this. Note that, for example, when the directions of PPDU transmissions on two links are correctly aligned, the PPDU alignment between the two links when STA4 transmits a (single or multiple) PPDU to STA2 may not be necessary.

[0078] During the time between the dummy frame and the PPDU from STA4 to STA2 on Link 2, STA4 may need to perform carrier sensing (CS) to determine the channel state. If the channel becomes busy during this time, STA4 cannot transmit a (single or multiple) PPDU from STA4 to STA2 and can start a new channel contention.

[0079] FIG. 20 shows an example embodiment 170 in which STA4 transmits a PPDU to STA2 on Link 2 immediately after accessing the channel. The MLD, STA, and Link are the same as those shown in FIG. 19.

[0080] It can be seen that STA1 has obtained the TXOP and has started receiving transmissions from STA3 (112) (172). Then, while STA1 is receiving on Link 1, STA4 obtains the channel access right to Link 2 for transmission to STA2 and transmits a (single or multiple) PPDU 174 to STA2 without the delay required to prevent interference. Therefore, the PPDU from STA4 is immediately received by STA2.

[0081] FIG. 21 shows Embodiment Example 190 in which STA4 reserves a TXOP on Link 2 using a shared frame. The MLD, STA, and Link are the same as those shown in FIG. 17.

[0082] Here too, it can be seen that STA1 has acquired a TXOP and started transmission 114 to STA3 (112). Next, while STA1 is transmitting on Link 1, STA4 acquires channel access rights to Link 2 for transmission to STA2 and transmits a shared frame 192 as shown in FIG. 23 to enable sharing of the TXOP by other STAs. Then, while STA1 is transmitting to STA3 (114), STA4 shares the TXOP with other STAs (194).

[0083] STA4 shares the TXOP with other STAs before transmitting a PPDU to STA2 (i.e., the PPDU from STA4 to STA2 in the figure). That is, other STAs can transmit during the shared TXOP time (i.e., the time between the shared frame and the PPDU from STA4 to STA2). The shared TXOP time can be obtained, for example, from the TXOP sharing time field in the shared frame. The transmission of other STAs cannot exceed the TXOP sharing time. Then, STA4 stops sharing the TXOP and transmits packet 156 to STA2.

[0084] Note that, for example, in a situation where the directions of PPDU transmission on two links match, PPDU alignment between the two links may not be required when STA4 transmits a (single or multiple) PPDU to STA2.

[0085] In at least one embodiment / mode / case, the shared frame is replaced with a multi-user (MU) RTS TXOP sharing (TXS) frame. STA4 can also transmit a trigger frame instead of the shared frame to trigger some transmissions before starting transmission to STA2. STA4 can exchange frames with other STAs before starting transmission to STA2.

[0086] FIG. 22 shows an example embodiment 210 in which STA4 waits in a state where the backoff is zero to communicate with the target receiving side on Link 2. MLD, STA, and the link are the same as those shown in FIG. 17.

[0087] Here too, it can be seen that STA1 has acquired the TXOP and started transmission 114 to STA3 (112). After that, while STA1 is transmitting on Link 1, STA4 counts down the backoff (BO) of Link 2 to zero and maintains the BO count at zero as described with reference to FIG. 23.

[0088] If STA4 can transmit a PPDU to STA2 (i.e., the PPDU from STA4 to STA2 in the figure), STA4 accesses the channel and transmits (214) a (single or multiple) PPDU 156 to STA2.

[0089] Note that when the directions of PPDU transmission on the two links correctly match, etc., PPDU alignment between the two links when STA4 transmits a PPDU to STA2 may not be necessary.

[0090] 3.3.3. Frame Format FIG. 23 shows an example embodiment 230 of a shared frame having the following fields.

[0091] The Frame Control field indicates the type of the frame. The Duration field contains NAV information used for CSMA / CA channel access. The RA field contains the address of the frame recipient. This RA field can also be broadcast. The TA field contains the address of the STA that transmitted the frame.

[0092] TXOP Common Information Field. Other STAs can compete for the channel to obtain a TXOP, but they need to end their own TXOP (not transmit beyond the TXOP) before the TXOP sharing ends. The TXOP sharing Indication field indicates whether TXOP sharing is permitted. This field can consist of a 1-bit indication (flag). For example, if this field is set to the first state (e.g., "1"), TXOP sharing is permitted. If this field is set to the second state (e.g., "0"), TXOP sharing is not permitted. When the receiving STA receives this field, it recognizes that it can transmit during the TXOP sharing time if this field is set to the TXOP sharing state. The TXOP sharing Time field indicates the time that the receiving STA can use for transmission after receiving this frame. The transmission of the receiving STA must not exceed the TXOP sharing time. When the RA is a broadcast, the receiving STA competes for the channel before transmission.

[0093] The Access Class field is also included. The AC constraint field indicates whether only the AC specified in the ACI field can be transmitted during the TXOP sharing time. This field can include a 1-bit indication. For example, when set to the first state (e.g., "1"), the receiving STA can only transmit traffic from the AC specified in the ACI field. Otherwise, the STA can transmit traffic from all ACs. The ACI field indicates the ACs that can transmit traffic during the TXOP sharing time. The format of this field is the same as the ACI bitmap field or the ACI high field shown in FIG. 10.

[0094] 4.4. Cooperation on the Link of the NSTR Link Pair To simplify the description of the embodiments, the network topology shown in FIG. 15 is used in the flowcharts and embodiments.

[0095] In this section, a method called NSTR coordination will be described, in which when STA1 and STA4 are the TXOP owners on Link 1 and Link 2 respectively, STA4 requests cooperation in transmission on both Link 1 and Link 2. When NSTR coordination of transmission occurs, either MLD1 or MLD2 arranges for transmission simultaneously on both links (i.e., performs the function of the TXOP owner). Also, the MLD that arranges for transmission can perform simultaneous transmission or reception on the two links to avoid in-device coexistence (IDC) interference between the two links.

[0096] 4.4.1. NSTR Request Process FIG. 24 shows an example embodiment 250 in which STA4 requests NSTR coordination so that either MLD1 or MLD2 arranges for transmission simultaneously on both Link 1 and Link 2. Note that the numbers of MLDs and STAs are only used for distinguishing MLDs and STAs, and it should be understood that the flowchart is not limited to any specific numbered MLD or STA.

[0097] When STA1 belonging to MLD1 is the TXOP owner on Link 1 (252), STA4 belonging to MLD2 has the right to access the channel on Link 2 and plans to communicate with STA2 belonging to MLD1.

[0098] Next, in block 254, STA4 requests STA2 or MLD1 to let MLD1 (or MLD2) arrange for transmission simultaneously on both Link 1 and Link 2. Note that when STA4 accesses the channel on Link 2, if STA1 is transmitting on Link 1, STA4 may not be able to transmit to STA2 on Link 2. By way of example and not limitation, STA4 can occupy the channel using the method described in Section 4.3 and transmit a packet to STA2 at the correct timing.

[0099] In check 256, it is determined whether MLD (MLD1) has accepted the request. If the condition is satisfied, MLD1 (or MLD2) arranges for simultaneous transmission on both Link 1 and Link 2 (258) in order to eliminate the possibility of in-device coexistence (IDC) interference. Note that in some cases, MLD1 (or MLD2) can stop arranging for transmission when one of the TXOPs on the two links ends.

[0100] On the other hand, if check 256 is not satisfied because the request has not been accepted, in block 260, STA4 stops the current TXOP.

[0101] Figure 25 shows an example embodiment 270 in which STA2 or MLD1 responds to an NSTR coordination request. When STA1 is the TXOP owner on Link 1, STA2 receives from STA4 on Link 2 an NSTR coordination request that enables MLD1 (or MLD2) to arrange for simultaneous transmission on both links (272).

[0102] In check 272, it is determined whether the request has been accepted. If the request has been accepted, in block 276, MLD1 responds to MLD2 indicating that it has accepted the request. Thereafter, MLD1 (or MLD2) begins to arrange for simultaneous transmission on both links (278).

[0103] On the other hand, if it is determined in block 274 that the request has been rejected by STA2 or MLD1, options are determined in block 280. If option 1 is selected (282), STA2 or MLD1 responds to MLD2 indicating that the request has been rejected. On the other hand, if option 2 is selected, STA2 or MLD1 can reject the request without the need to send a response (284).

[0104] 4.4.2. Examples of NSTR Request Operations In this section, a plurality of examples in which, as described in section 4.3, STA4 requests NSTR coordination from MLD1 after accessing the channel will be described in detail.

[0105] Figure 26 shows Embodiment Example 310 in which STA4 requests NSTR cooperation to enable MLD1 to schedule transmissions on the NSTR link. This figure shows MLD2 76 having associated STA3 82 and STA4 84 communicating with MLD1 74 having associated STA1 78 and STA2 80.

[0106] STA1 acquires TXOP112 on Link 1 and starts receiving from STA3 on Link 1 (312). STA4 first transmits an NSTR cooperation request frame (NSTRCrd Req as shown) 314 to STA2 via Link 2 in order to request that MLD1 schedule transmissions on both Link 1 and Link 2. STA4 can also indicate in the NSTR cooperation request frame the NSTR cooperation time for MLD1 to schedule transmissions on both links. The buffer status of STA4 or MLD2 can also be transmitted by the NSTR cooperation request frame. As shown, STA2 can receive the NSTR cooperation request frame simultaneously while STA1 is receiving, even though STA1 is the TXOP owner on Link 1.

[0107] Next, MLD1 accepts the NSTR cooperation request (315) and returns NSTR cooperation response frames (NSTRCrd Res as shown) 316, 318 to MLD2 and associated STA3 and STA4 to accept the sharing request. Note that the transmission of the NSTR cooperation response frame on Link 1 may not be necessary and this frame can also be replaced by any other PPDU transmitted by STA1. On the other hand, MLD1 is scheduling transmissions simultaneously on both links. For example, MLD1 can control transmissions or receptions on both links simultaneously.

[0108] Note that the formats of the NSTR coordination request frame and the NSTR coordination response frame can be the same as those in FIG. 32. In at least one embodiment / mode / case, the NSTR coordination request frame can include a transfer request (RTF) frame as shown in FIG. 33, or a BSR frame as defined in IEEE802.11ax, and the NSTR coordination response frame is a trigger frame as defined in IEEE802.11ax.

[0109] When MLD1 takes over the TXOPs on both links, since these two links belong to the same NSTR link pair, the PPDU transmission directions on these links should be the same. This figure shows that PPDU transmissions 320 and 322 are being executed within the TXOP.

[0110] Note that since the NSTRCrd Res on link 2 (from STA2 to STA4) can provide the result of the NSTR coordination, the NSTRCrd Res on link 1 (from STA1 to STA3) shown in the figure can be replaced by any other PPDU. That is, there is no need to transmit the NSTRCrd Res on link 1 (from STA1 to STA3).

[0111] FIG. 27 shows an example embodiment 330 in which STA4 requests NSTR coordination to enable the transmission arrangement on the NSTR link by MLD2. The MLD, STA, and link are the same as those shown in FIG. 26.

[0112] STA1 acquires TXOP112 on Link 1 and starts receiving from STA3 on Link 1 (312). STA4 transmits an NSTR coordination request frame (NSTRCrd Req as shown in the figure) 314 to request transmission arrangements on both Link 1 and Link 2. STA4 can also indicate in the NSTR coordination request frame the period during which MLD1 should arrange transmissions on both links. The buffer status of STA4 or MLD2 can also be transmitted by the NSTR coordination request frame. As shown in the figure, STA2 can receive a sharing request frame when STA1 is receiving, even though STA1 is the TXOP owner of Link 1.

[0113] Next, MLD1 accepts the NSTR coordination request (315) and returns NSTR coordination response frames (NSTRCrd Res as shown in the figure) 316 and 318 to MLD2 that accept the NSTR coordination request. Note that the transmission of the NSTR coordination response frame on Link 1 may not be necessary, and this frame can also be replaced by any other PPDU transmitted by STA1. Thereafter, MLD2 starts arranging transmissions on both links (319). If MLD2 takes over the TXOPs on both links, since these two links belong to the same NSTR link pair, the PPDU transmission directions on these links should be the same. This figure shows PPDU transmission 332 from STA3 to STA1 and simultaneous PPDU transmission 334 from STA4 to STA2.

[0114] Note that the formats of the NSTR coordination request frame and the NSTR coordination response frame can be the same as those shown in FIG. 32. In at least one embodiment / mode / case, the NSTR coordination request frame includes a transfer request (RTF) frame as shown in FIG. 33, or a BSR frame as defined in IEEE802.11ax, and / or the NSTR coordination response frame is a MU-RTS TXS trigger frame as defined in IEEE802.11be.

[0115] FIG. 28 shows an example embodiment 350 in which MLD1 rejects an NSTR coordination request. The MLD, STA, and link are the same as those shown in FIG. 27.

[0116] STA1 acquires TXOP112 on Link 1 and starts receiving from STA3 on Link 1 (352). At this time, STA4 on Link 2 transmits an NSTR coordination request frame (NSTRCrd Req as shown) 354 to request that either MLD1 or MLD2 schedule transmissions on both Link 1 and Link 2. STA4 can also indicate in the NSTR coordination request frame the time when the MLD should schedule transmissions on both links. The buffer status of STA4 or MLD2 can also be transmitted by the NSTR coordination request frame. As shown, STA2 can receive a share request frame while STA1 is receiving, even though STA1 is the TXOP owner of Link 1.

[0117] MLD1 rejects the NSTR coordination request, and STA2 returns an NSTR coordination response frame (NSTRCrd Res as shown) rejecting the NSTR coordination request to STA4 (358). On the other hand, STA1 can continue transmitting on Link 1 (356). Thereafter, MLD2 can end the TXOP on Link 2 and re-contend for the channel.

[0118] Note that the format of the NSTR coordination request frame can be the same as that shown in FIG. 32.

[0119] FIG. 29 shows an example embodiment 370 in which STA4 permits (requests) MLD1 to schedule transmissions on the NSTR link. The MLD, STA, and link are the same as those shown in FIG. 28.

[0120] STA1 acquires TXOP112 on Link 1 and starts receiving from STA3 on Link 1 (312). At this time, STA4 on Link 2 sends an NSTR coordination indication frame (NSTRCrd Ind as shown in the figure) 314 to STA2, indicating (requesting) that MLD1 should arrange transmissions on both Link 1 and Link 2. STA4 can also choose to indicate in the NSTR coordination indication frame the time when MLD1 should arrange transmissions on both links. It is also possible to send the buffer status of STA4 or MLD2 by the NSTR coordination request frame. As shown in the figure, although STA1 is the TXOP owner of Link 1, STA2 can receive the NSTR coordination indication frame simultaneously when STA1 is receiving.

[0121] After that, MLD1 accepts the request and starts arranging PPDU transmissions on both links. As shown in the figure, STA1 can start sending PPDUs 372 and 376 to STA3 on Link 1, and STA2 can start sending PPDUs 374 and 378 to STA4 on Link 2. When MLD1 arranges transmissions on the two links, it should arrange them so that the transmission directions on the two links are the same. During the transmission on each link, it is also possible to either match the PPDUs or not.

[0122] Note that the format of the NSTR indication frame can be the same as that shown in Figure 32, or it can be a MU-RTS TXS trigger frame as defined in IEEE802.11be.

[0123] Also, the first PPDU on Link 2 (from STA2 to STA4) can carry a confirmation response frame indicating that the NSTRCrd Ind frame has been received normally.

[0124] Figures 30 and 31 show Example Embodiment 390 of reusing a Reverse Direction Grant (RDG) for NSTR coordination. The PPDU of this figure can carry an extended CAS Control subfield as shown in FIG. 34 within its HT control field.

[0125] MLD, STA, and the link are the same as those shown in FIG. 29. STA1 acquires TXOP112 on Link 1 and starts receiving from STA3 on Link 1 (392).

[0126] STA4 sets the RDG to active (e.g., "1") and transmits a PPDU 394 with the NSTR coordination indication set to active (e.g., "1") on Link 2 to indicate that MLD1 can schedule transmissions on both Link 1 and Link 2.

[0127] Thereafter, MLD1 schedules transmissions on both Link 1 and Link 2 using PPDUs 398, 400, 402, 404, 406, 408, 410, and 412. The RDG / More PPDUs field in the PPDU transmitted by MLD1 is set to active (e.g., "1") to indicate ongoing NSTR coordination. An NSTR coordination period 396 defining the boundary of PPDU transmissions is shown.

[0128] The RDG / additional PPDU fields within the PPDU are set to ensure that the PPDU transmission directions on both links are the same. For example, if the RDG is inactive (e.g., "0") on Link 1 and the additional PPDU is active (e.g., "1") on Link 2, the next PPDU on Link 1 and Link 2 is transmitted by MLD1. If the RDG is set to active on Link 1 and at the same time the additional PPDU is set to inactive on Link 2, the next PPDU on Link 1 and Link 2 is transmitted by MLD2. If the additional PPDU is set to active (e.g., "1") on Link 1 and at the same time the RDG is set to inactive (e.g., "0") on Link 2, the next PPDU on Link 1 and Link 2 is transmitted by MLD2. If the additional PPDU is inactive (e.g., "0") on Link 1 and the RDG is active (e.g., "1") on Link 2, the next PPDU on Link 1 and Link 2 is transmitted by MLD1.

[0129] Note that the RDG subfield and the additional PPDU subfield share the same bits within the PPDU. When the STA is the TXOP owner, the STA transmits the RDG field within the PPDU. When the STA is the TXOP responder, the STA transmits the additional data field within the PPDU. When the NSTR coordination indication within the PPDU is inactive, the NSTR coordination ends.

[0130] 4.4.3. NSTR Coordination Format FIG. 32 shows an exemplary embodiment 430 of an NSTR coordination request, response, and indication frame having the following fields. Thus, it should be understood that this frame is utilized for NSTR coordination requests, NSTR coordination responses, and NSTR coordination indications in at least one embodiment.

[0131] The Frame Control field indicates the type of the frame. This frame can indicate whether this frame is an NSTR cooperation request frame, an NSTR cooperation response frame, or an NSTR cooperation indication frame. In at least one embodiment / mode / case, this field only indicates that the frame is carrying NSTR cooperation information, and does not indicate whether it is an NSTR cooperation request frame, an NSTR cooperation response frame, or an NSTR cooperation indication frame. The Duration field contains the NAV information used for CSMA / CA channel access. The RA field contains the address of the recipient of the frame. The TA field contains the address of the STA that sent the frame.

[0132] The NSTRCrd frame type field is set to indicate the type of the NSTR cooperation frame. When this field is set to "Request", the frame is an NSTR cooperation request frame. In response to this request, the receiving side determines whether to accept the request based on the NSTR cooperation information indicated in the frame. The receiving side of this frame can also respond with an NSTR cooperation response frame to indicate its determination. When this field is set to "Response", the frame is an NSTR cooperation response frame. When this frame is received, the result (determination) of the NSTR cooperation request is determined. If the request is accepted, both the sending side and the receiving side of this frame follow the NSTR cooperation information indicated in this frame. If the request is rejected, the receiving side of this frame can end the current TXOP and seek the channel to re-contend. When this field is set to "Indication", this frame is an NSTR cooperation indication frame. Therefore, the receiving side of this frame determines that it can take over the TXOP resource indicated in the NSTR cooperation indication frame and perform the function of the TXOP owner.

[0133] The NSTRCrd information field is set to indicate NSTR coordination information. When the STA or MLD receives this information, it can use the information in this field to perform NSTR coordination. The NSTRCrd indication field is an NSTR coordination indication set to indicate the NSTR coordination state. This field can be implemented as a 1-bit indication.

[0134] When this field is set to active (e.g., "1") within the NSTR coordination request frame, it indicates that the transmitting side is requesting NSTR coordination. Otherwise, this field is set to inactive (e.g., "0"). When the receiving side receives this field within the NSTR coordination request frame, it recognizes that the transmitting side is requesting NSTR coordination and can decide whether to accept or reject this request and indicate this decision within the NSTR coordination response frame.

[0135] When this NSTR coordination field is set to active (e.g., "1") within the NSTR coordination response frame, it indicates that the transmitting side of the NSTR coordination response frame accepts the NSTR coordination request from the receiving side of the NSTR coordination response frame. Otherwise, this field is set to inactive (e.g., "0") to indicate that the transmitting side rejects the NSTR coordination request. When this field is set to active (e.g., "1"), the transmitting and receiving sides of this frame start NSTR coordination. Otherwise, the receiving side recognizes that the NSTR coordination request has been rejected, can end the current TXOP, and re-contend for the channel.

[0136] When this NSTR coordination field is set to active (e.g., "1") within the NSTR coordination indication frame, it indicates that the transmitting side of the NSTR coordination indication frame permits the receiving side to arrange for transmission during the NSTR coordination time. As a result, the receiving side can inherit the TXOP and perform the function of the TXOP owner during the NSTR coordination time. Otherwise, this field is set to inactive (e.g., "0").

[0137] The NSTR coordinator field is set to indicate which MLD should arrange for transmission or perform the function of the TXOP owner during the NSTR coordination period via the link.

[0138] When this field is set in the transmitting side MLD of the NSTR coordination request frame, it represents that the transmitting side MLD should perform the function of the TXOP owner on both links of the NSTR link pair during the NSTR coordination time.

[0139] When this field is set in the receiving side MLD of the NSTR coordination request frame or the NSTR coordination indication frame, it indicates that the receiving side MLD should perform the function of the TXOP owner and arrange for transmission on both links of the NSTR link pair during the NSTR coordination time.

[0140] The NSTRCrd time field is set to indicate the NSTR coordination time via the link. This field indicates that the NSTR coordinator can arrange for transmission or perform the function of the TXOP owner during subsequent NSTR coordination times.

[0141] The AC constraint field is set to indicate the AC for which traffic can be transmitted during the NSTR coordination time. Note that this field is only valid on the link on which this field is transmitted. If this field is valid on both links, transmissions on both links should follow the AC constraints indicated by this field.

[0142] This AC constraint field can be set to a single AC. In at least one embodiment / mode / case, only traffic from that AC can be transmitted during the NSTR coordination time. In some cases, this field can represent the primary AC during the NSTR coordination time. The transmitting and receiving sides of this field should perform transmission according to transmission rules such as the TXOP sharing rules of IEEE802.11ax during the NSTR coordination time. In at least one embodiment / mode / case, during the NSTR coordination time, traffic from an AC with a priority equal to or higher than the AC indicated in this field can be transmitted.

[0143] This AC constraint field can also include an AC bitmap where each bit represents an AC. When a bit in this field is set to active (e.g., "1"), traffic from the AC corresponding to this bit is transmitted during the NSTR coordination time. Otherwise, this bit is set to inactive (e.g., "0") so that traffic from the AC corresponding to this bit is not transmitted during the NSTR coordination time.

[0144] This AC constraint field can also be composed of a 1-bit indication. When this bit is set to active (e.g., "1"), only traffic from the primary AC can be transmitted during the NSTR coordination time. On the other hand, when this bit is set to inactive (e.g., "0"), traffic from all ACs can be transmitted during the NSTR coordination time. TXOP sharing defined in IEEE802.11ax can be permitted.

[0145] The NSTR link ID (NSTR link ID) field is set to indicate to the other link of the NSTR link pair that the NSTR coordinator should arrange for transmission to perform the function of the TXOP owner during NSTR coordination.

[0146] In the NSTR coordination request or indication frame, the Min MPDU size field is set to indicate the minimum MPDU size that the STA setting this field requests to transmit during the NSTR coordination time. At the start of the NSTR coordination process, the MDPU transmitted by the STA setting this field should be larger than the Min MPDU size. This field can be set in multiple ways shown below as an example, not by limitation. When the NSTR coordination request is accepted, this field can be set in the NSTR coordination response frame by replicating the value of the corresponding NSTR coordination request frame. This field can also be set in the NSTR coordination response frame to indicate the minimum size of the MPDU that the STA setting this field transmits during the NSTR coordination time. Note that this field can also include the minimum MSDU size indicating the minimum MSDU or A-MSDU size that the STA setting this field transmits during the NSTR coordination time.

[0147] In the NSTR coordination request or indication frame, the Transmitting time field is set to indicate the minimum time that the STA setting this field requests to transmit a PPDU to the recipient of this field during the NSTR coordination time. At the start of the NSTR coordination, at least this time should be allocated for transmission by the STA setting this field. This field can be set in multiple ways shown below as an example, not by limitation. When the NSTR coordination request is accepted, this field can be set in the NSTR coordination response frame by replicating the value of the corresponding NSTR coordination request frame. This field can also be set in the NSTR coordination response frame to indicate the minimum time required for the STA setting this field to perform transmission during the NSTR coordination time.

[0148] The Buffer Status Report field is set by the transmitting STA to indicate its buffer status. When the NSTR coordinator receives this field, it should arrange for transmission during the NSTR coordination time based on the received buffer status of the transmitting side. In at least one embodiment, this field can be formatted as defined in IEEE802.11ax.

[0149] Figure 33 shows an example embodiment 450 of an RTF frame. The Frame Control field indicates the type of the frame. The Duration field contains the NAV information used for CSMA / CA channel access. The RA field contains the address of the recipient of the frame. The TA field contains the address of the STA that transmitted the frame. The BSR control field is set by the transmitting side to indicate the status of the buffer. When a STA receives this field, it can arrange for transmission based on the received buffer status of the transmitting side. The format of this field can be implemented to be the same as that defined in IEEE802.11ax. The Trigger type field is set to indicate the type of trigger that the transmitting side requests the receiving side to transmit after receiving this frame. The Common Information (Info) field is the same as the common information field of the trigger frame indicated by the trigger type. The receiving side should replicate the common information in the solicited trigger frame to be transmitted. The User Information (Info) field is the same as the user information field of the trigger frame indicated by the trigger type. The receiving side should replicate the common information in the solicited trigger frame to be transmitted.

[0150] Figure 34 shows an example embodiment 470 of an extended CAS control subfield variant of the A-control subfield.

[0151] The AC constraint field can be represented in different ways, including the use of a 1-bit indication. By way of example and not limitation, the implementation of a 1-bit indicator (flag) is shown below. When this bit is set to the first state (e.g., "1"), only traffic from the primary AC can be transmitted during the NSTR coordination time. On the other hand, when this bit is set to the second state (e.g., "0"), traffic from any AC can be transmitted during the NSTR coordination time. It is possible to permit TXOP sharing as defined in IEEE802.11ax.

[0152] The RDG / More PPDU field is a multi-purpose field. When the sender of this field is the TXOP owner, this field is a Reverse Direction Grant (RDG) field. When this bit is set to active (e.g., "1"), the next PPDU should be transmitted from the receiving side. When this bit is set to non-active (e.g., "0"), the next PPDU is also transmitted by the transmitting side.

[0153] When the sender of this field is the TXOP responder, this field is a More PPDU field. When this bit is set to active (e.g., "1"), the next PPDU should be transmitted by the transmitting side. When this bit is set to non-active (e.g., "0"), the next PPDU should be transmitted by the receiving side.

[0154] The subfield of the PSRT PPDU can be the same as that defined in IEEE802.11ax.

[0155] The NSTRCrd indication field is an NSTR coordination indication that is set to indicate the NSTR coordination state. This field can be implemented in multiple ways, including the use of a 1-bit indication (flag). When this field is set to a first state (e.g., "1") within the NSTR coordination indication frame, it indicates that NSTR coordination is in progress. The MLD that transmits the next PPDU should ensure that the direction of the PPDU on the link is the same. Otherwise, this field is set to a second state (e.g., "0").

[0156] The NSTRCrd time field is set to indicate the NSTR coordination time via the link. This field indicates that the NSTR coordinator can schedule transmissions or perform the function of the TXOP owner during subsequent NSTR coordination times.

[0157] The ACI, Scaling Factor, and Queue Size fields are fields that represent the buffer state on the transmitting side. The receiving side can use this information to schedule transmissions. The ACI field indicates the access category of the buffer reported by the transmitting side. The Scaling Factor field indicates the unit of the queue size. The encoding of this field is the same as that of IEEE802.11ax. The Queue Size field indicates the amount of buffered traffic on the transmitting side in units of the scaling factor.

[0158] 4.5. Examples of Another Network Topology The example in the previous Section 4.4.2 showed the NSTR coordination between MLD1 and MLD2 when STA1 belonging to MLD1 is the TXOP owner on Link 1 and communicates with STA3 belonging to MLD2. However, when STA4 acquires the channel access right on Link 1 and starts NSTR coordination, it is possible that STA1 is the TXOP owner but not communicating with STA3. This section describes such a scenario.

[0159] Figure 35 shows an example embodiment 490 of the network topology as described in this section. Comparing with FIG. 15, another station STA5 that can communicate with STA1 on Link 1 is added to the network topology shown in FIG. 35. STA5 can be a STA belonging to an MLD such as MLD3 as shown in the figure, or a STA not belonging to the MLD.

[0160] It should be understood that the embodiment 490 is an example of the network topology used to explain the operations in this section. Since the devices and methods of the present disclosure are not limited to any specific topology, this topology should be understood as being shown as an example rather than being limiting, similar to FIG. 15. Also, the specific MLDs, STAs, and links referred to throughout the present disclosure are merely shown to simplify the understanding of the operations.

[0161] As shown in the example diagram, assume that there are STAs on three MLDs 494, 496, and 498 as seen within a structure 492 such as a conference room. STA1 500 and STA2 502 belong to MLD1 494, STA3 504 and STA4 506 belong to MLD2 496, and STA5 508 and STA6 510 belong to MLD3 498. STA1 and STA2 are associated with (communicate with) STA3 and STA4 respectively via Link 1 512 and Link 2 514. Note that Link 1 and Link 2 are one NSTR link pair of MLD1. STA1 and STA5 communicate via Link 1 516 which is a peer-to-peer (P2P) communication.

[0162] In this figure, consider the case where MLD2 is the STR AP and MLD1 and MLD3 are non-AP MLDs related to MLD2. Although the figure does not show the association between MLD2 and MLD3, this association can be achieved through the association between the AP STA belonging to MLD2 and the non-AP STA belonging to MLD3 via Link 1 or Link 2, or any other link.

[0163] All STAs use CSMA / CA for random channel access on all links. Also, in the network topology of Fig. 35, assume that MLD2 can determine the transmission and reception status of STA1 on Link 1, for example, because STA3 belonging to MLD2 monitors the transmission between STA1 and STA5 on Link 1 by responding to the check of the TA and RA fields of the TDLS frame. Also, MLD2 can share the status information of STA1 on Link 1 with STA4 belonging to it on Link 2.

[0164] In the example shown in Section 4.3, the channel access of STA4 when STA1 is communicating with STA3 was shown. However, when STA4 accesses the channel, it is also conceivable that STA1 is communicating with another STA that does not belong to the same MLD as STA4. In this section, it is shown that the same channel access method shown in Section 4.3 also operates in such a scenario.

[0165] Fig. 36 shows Embodiment Example 530 in which STA4 reserves the TXOP of Link 2 using a dummy frame, similar to Fig. 17 except that STA1 is transmitting to STA5. The network topology of this example is shown in Fig. 35.

[0166] STA1 acquires a TXOP (532) and then starts transmitting to STA5 (534). When STA4 acquires channel access rights for transmission to STA2, STA1 is transmitting on Link 1. Therefore, STA4 transmits a dummy frame (536) to reserve a short TXOP. STA1 finishes transmitting before the reserved short TXOP ends and starts receiving from STA5 on Link 1 (540). When STA1 starts receiving, STA4 transmits PPDU 542 to STA2, and STA2 can receive this without the possibility of in-device coexistence interference. Note that PPDU alignment between the two links can be unnecessary. However, the directions of PPDU transmission on the two links should be the same. Also, the transmission information of Link 1 (the preamble and MAC header of the PPDU) can assist STA4 in transmitting a PPDU (from STA4 to STA2) when STA1 is receiving the PPDU.

[0167] STA4 may need to perform carrier sensing (538 CS) to detect the channel state during the time between the dummy frame on Link 2 and the PPDU from STA4 to STA2. If the channel becomes busy during this time, STA4 cannot transmit the PPDU from STA4 to STA2 and can start a new channel contention.

[0168] Note that MLD2 is STR MLD. STA4 can start and finish transmitting a PPDU (which can also be multiple PPDUs) to STA2 during the time when STA4 is receiving on Link 1.

[0169] The example shown in Section 4.4 shows an example where STA4 starts NSTR cooperation when STA1 is communicating with STA3. However, in some cases, when STA4 accesses the channel, STA1 may be communicating with another STA that does not belong to the same MLD as STA4. This section shows that the NSTR cooperation mechanism also operates in such scenarios.

[0170] FIG. 37 shows Embodiment Example 570 in which MLD1 accepts an NSTR coordination request and arranges for transmission on the NSTR link for different MLDs. The network topology of this example is shown in FIG. 35.

[0171] STA1 acquires a TXOP (532) and then starts receiving from STA5 (572). STA4 first transmits an NSTR coordination request frame (NSTRCrd Req as shown) 574 to STA2, requesting MLD1 to arrange for transmission on both Link 1 and Link 2. STA4 can also indicate in the NSTR coordination request frame the period during which MLD1 should arrange for transmission on both links. The buffer status of STA4 or MLD2 can also be transmitted by the NSTR coordination request frame. As shown, STA2 can receive the NSTR coordination request frame simultaneously while STA1, which is communicating with STA5, is receiving, even though STA1 is the TXOP owner of Link 1.

[0172] Next, MLD1 accepts NSTR coordination (575), and STA2 returns an NSTR coordination response frame (NSTRCrd Res as shown) 578 to STA4, which accepts the NSTR coordination request when STA1 of MLD1 is transmitting a PPDU 576 to STA5. MLD1 arranges for transmission simultaneously on both links. Note that the TXOP responder on Link 1 is STA5, which does not belong to MLD2. In this case, when MLD1 starts arranging for transmission on the two links, it continues the transmission shown as PPDUs 576 and 578 with STA5 on Link 1 and starts the transmission shown as PPDU 582 with STA4 on Link 2. When MLD1 arranges for transmission on the two links, the transmission directions on these two links should be the same. During transmission on each link, the PPDUs can or cannot be made to match.

[0173] Note that the formats of the NSTR coordination request frame and the NSTR coordination response frame can be the same as those shown in FIG. 32. In at least one embodiment / mode / case, the NSTR coordination request frame is an RTF frame as shown in FIG. 33, or a BSR frame as defined in IEEE802.11ax, and the NSTR coordination response frame is a trigger frame as defined in IEEE802.11ax.

[0174] 5. General scope of embodiments In this specification, embodiments of the present technology can be described with reference to methods and systems according to embodiments of the present technology, which can also be implemented as computer program products, and / or procedures, algorithms, steps, operations, mathematical formulas, or other flowchart of computational expressions. In this regard, each block or step of the flowchart, and combinations of blocks (and / or steps) of the flowchart, and any procedure, algorithm, step, operation, mathematical formula, or computational expression can be implemented by various means such as software including one or more computer program instructions embodied in hardware, firmware, and / or computer-readable program code. As understood, such any computer program instructions can be executed by one or more computer processors including, but not limited to, general-purpose computers or special-purpose computers, or any other programmable processing device for producing machines, so that the computer program instructions executed on the computer processor or other programmable processing device can create means for implementing the specified functions (singular or plural).

[0175] Accordingly, the blocks of the flowcharts described herein, as well as procedures, algorithms, steps, operations, mathematical formulas, or computational expressions, support computer program instructions for performing (single or plural) specific functions, in the form of combinations of means for performing (single or plural) specific functions, combinations of steps for performing (single or plural) specific functions, and computer-readable program code logic means. Also, it will be understood that each block of the flowcharts described herein, as well as any procedure, algorithm, step, operation, mathematical formula, or computational expression, and combinations thereof, can be implemented by a dedicated hardware-based computer system for performing (single or plural) specific functions or steps, or by a combination of dedicated hardware and computer-readable program code.

[0176] Furthermore, these computer program instructions, embodied in the form of computer-readable program code or the like, can be stored in one or more computer-readable memories or memory devices that direct a computer processor or other programmable processing device to function in a specific manner, such that the instructions stored in these computer-readable memories or memory devices produce an article of manufacture that includes instruction means for performing the functions specified within (single or plural) blocks of (single or plural) flowcharts. The computer program instructions can be executed by a computer processor or other programmable processing device to generate a computer-implemented process in which a series of operational steps are executed on the computer processor or other programmable processing device, and the instructions executed on the computer processor or other programmable processing device provide steps for performing the functions specified within (single or plural) blocks, (single or plural) procedures, (single or plural) algorithms, (single or plural) steps, (single or plural) operations, (single or plural) mathematical formulas, or (single or plural) computational expressions of (single or plural) flowcharts.

[0177] Furthermore, the terms "program" or "program executable statement" as used herein will be understood to mean one or more instructions that can be executed by one or more computer processors to perform one or more functions described herein. The instructions can be embodied in software, firmware, or a combination of software and firmware. The instructions can be stored locally on a non-transitory medium of the device, or stored remotely, such as on a server, or a combination of local and remote storage of all or part of the instructions can be used. The remotely stored instructions can be downloaded (pushed) to the device automatically by the user's initiation or based on one or more factors.

[0178] Furthermore, the terms processor, hardware processor, computer processor, central processing unit (CPU), and computer as used herein are used synonymously to denote a device capable of executing instructions and communicating with an input / output interface and / or peripheral devices, and the terms processor, hardware processor, computer processor, CPU, and computer are intended to include single or multiple devices, single-core devices and multi-core devices, and variants thereof.

[0179] From the description herein, it will be understood that the present disclosure includes a plurality of technical implementations including, but not limited to, the following.

[0180] An apparatus for wireless communication in a network, comprising: (a) a wireless communication circuit as a station (STA) that executes multi-link operation via a plurality of links of a channel to communicate with other wireless stations (STAs) in the network and accesses the channel using carrier sense multiple access / collision avoidance (CSMA / CA); (b) a processor coupled to the wireless communication circuit to execute a communication protocol; (c) a non-transitory memory storing instructions executable by the processor for communicating with other STAs on the network; and (d) the instructions, when executed by the processor, cause: (d)(i) a first multi-link device (MLD1) to be configured to perform non-simultaneous transmission and reception (NSTR) communication and be the transmitter opportunity (TXOP) owner of a first link (Link 1); (d)(ii) the STA to operate within a second multi-link device (MLD2) and access the channel on a second link (Link 2) for transmission to MLD1; (d)(iii) when MLD1 is receiving on Link 1, MLD2 to immediately transmit to MLD1 via Link 2; and (d)(iv) when MLD1 is transmitting on Link 1, MLD2 to transmit a frame via Link 2 to occupy the channel, and then when MLD1 is receiving on Link 1, MLD2 to perform another frame transmission to MLD1, the apparatus performing one or more steps including the above.

[0181] An apparatus for wireless communication in a network, comprising: (a) a wireless communication circuit as a station (STA) that executes multi-link operation via a plurality of links of a channel and accesses the channel using carrier sense multiple access / collision avoidance (CSMA / CA) to communicate with other wireless stations (STAs) in the network; (b) a processor coupled to the wireless communication circuit to execute a communication protocol; (c) a non-transitory memory storing instructions executable by the processor for communicating with other STAs on the network; (d) the instructions, when executed by the processor, perform one or more steps including: (d)(i) associating the STA with a second multi-link device (MLD2) while associating another STA with a first multi-link device (MLD1) to perform non-simultaneous transmission and reception (NSTR) communication; (d)(ii) making MLD1 the transmitter opportunity (TXOP) owner of a first link (Link 1); (d)(iii) making the second MLD (MLD2) the TXOP owner of a second link (Link 2) and scheduling to transmit to MLD1 on Link 2; (d)(iv) transmitting a non-simultaneous transmission and reception (NSTR) adjustment request from MLD2 to MLD1 via Link 2; (d)(v) when MLD2 requests a response frame from MLD1, receiving from MLD1 a response frame indicating whether MLD1 has accepted or rejected the NSTR coordination request; (d)(vi) when the NSTR coordination request is accepted, arranging for transmission on both Link 1 and Link 2 by either MLD1 or MLD2, and then executing the transmission.

[0182] A method for performing wireless communication in a network, comprising: (a) a wireless communication circuit as a station (STA) executes multi-link operation via a plurality of links of a channel to communicate with other wireless stations (STA) in the network, and accesses the channel using carrier sense multiple access / collision avoidance (CSMA / CA); (b) a first multi-link device (MLD1) that becomes the transmitter opportunity (TXOP) owner of a first link (Link 1) executes non-simultaneous transmission and reception (NSTR) communication; (c) the STA associated with a second multi-link device (MLD2) accesses the channel on a second link (Link 2) for transmission to MLD1; (d) when MLD1 is receiving on Link 1, MLD2 immediately transmits to MLD1 via Link 2; and (e) when MLD1 is transmitting on Link 1, MLD2 transmits a frame via Link 2 to occupy the channel, and then when MLD1 is receiving on Link 1, MLD2 transmits another frame to MLD1.

[0183] A wireless communication system / apparatus for performing packet transmission, to which CSMA / CA and multi-link operation are applied, where Link 1 and Link 2 are the NSTR link pair of MLD1, and MLD1 is the TXOP owner on Link 1, the wireless communication system / apparatus comprising: (a) MLD2 accesses the channel on Link 2 and is scheduled to transmit to MLD1; (b) when MLD1 is receiving on Link 1, MLD2 immediately transmits to MLD1 on Link 2; and (c) when MLD1 is transmitting on Link 1, MLD2 transmits a frame to occupy the channel and transmits another frame to MLD1 when MLD1 is receiving on Link 1.

[0184] A wireless communication system / apparatus that executes packet transmission, to which CSMA / CA and multi-link operation are applied, where Link 1 and Link 2 are an NSTR link pair of MLD1, MLD1 is the TXOP owner on Link 1, MLD2 is the TXOP owner on Link 2 and is scheduled to transmit to MLD1 on Link 2, and the wireless communication system / apparatus includes: (a) MLD2 transmits an NSTR cooperation request to MLD1 via Link 2; (b) then MLD1 transmits a response frame to accept or reject the request; and (c) if the request is accepted, either MLD1 or MLD2 arranges for transmission on both Link 1 and Link 2.

[0185] In any previous implementation, an apparatus, system, or method in which MLD2 transmits a dummy frame not including a data packet to reserve a part of the TXOP and occupy the channel, and then, when MLD1 starts receiving on Link 1 before the end of the TXOP, transmits a frame including a data packet to MLD1 via Link 2.

[0186] In any previous implementation, an apparatus, system, or method in which, if MLD2 determines not to wait for the time when MLD1 is receiving on Link 1, MLD2 re-contends for the channel without increasing its contention window (CW).

[0187] In any previous implementation, an apparatus, system, or method in which MLD2 transmits a request to send (RTS) or a multi-user RTS (MU-RTS) incorporating padding to occupy the channel on Link 2.

[0188] In any previous implementation, an apparatus, system, or method in which MLD2 transmits a clear to send (CTS) to MLD1 or a CTS-to-Self to occupy the channel on Link 2.

[0189] MLD2 is a device, system, or method of any prior implementation that transmits a transmit opportunity (TXOP) sharing frame to occupy the channel on link 2.

[0190] MLD2 is a device, system, or method of any prior implementation that transmits a transmit opportunity (TXOP) sharing frame to share the TXOP with other STAs on link 2 until MLD1 starts receiving on link 1.

[0191] MLD2 is a device, system, or method of any prior implementation that transmits an NSTR coordination indication frame to start NSTR coordination without requesting a response frame from MLD1.

[0192] MLD2 is a device, system, or method of any prior implementation that executes the stop of its current TXOP in response to receiving a frame from MLD1 indicating that the NSTR coordination request has been rejected.

[0193] MLD1 can return nothing indicating the rejection of the NSTR coordination request, so MLD2 does not need to receive the rejection of the NSTR coordination request. This is a device, system, or method of any prior implementation.

[0194] MLD2 transmits a dummy frame without data packets to reserve a part of the TXOP to occupy the channel. Then, if MLD1 starts receiving on link 1 before the end of the TXOP, MLD2 transmits a frame containing data packets to MLD1 via link 2. This is a device, system, or method of any prior implementation.

[0195] If MLD2 decides not to wait for the time when MLD1 is receiving on link 1, MLD2 re-contends for the channel without increasing its contention window (CW). This is a device, system, or method of any prior implementation.

[0196] MLD2 is an apparatus, system, or method of any previous implementation that transmits a Request to Send (RTS) or Multi-User RTS (MU-RTS) incorporating padding to occupy the channel on Link 2.

[0197] MLD2 is an apparatus, system, or method of any previous implementation that transmits a Clear to Send (CTS) to MLD1 or CTS-to-Self to occupy the channel on Link 2.

[0198] MLD2 is an apparatus, system, or method of any previous implementation that transmits a Transmit Opportunity (TXOP) sharing frame to occupy the channel on Link 2.

[0199] MLD2 is an apparatus, system, or method of any previous implementation that transmits a Transmit Opportunity (TXOP) sharing frame to share a TXOP with other STAs on Link 2 until MLD1 starts receiving on Link 1.

[0200] MLD2 is an apparatus, system, or method of any previous implementation that transmits a frame reserving a short TXOP to occupy the channel and, if there is a chance before the end of the TXOP, can transmit a frame to MLD1.

[0201] MLD2 is an apparatus, system, or method of any previous implementation that can decide not to transmit to MLD1 via Link 2.

[0202] MLD2 is an apparatus, system, or method of any previous implementation that can re-contend for the channel without increasing the CW if it cannot wait for the time when MLD1 is receiving on Link 1.

[0203] MLD2 is an apparatus, system, or method of any previous implementation that can transmit an RTS or MU-RTS including padding to occupy the channel on Link 2.

[0204] MLD2 can be a device, system, or method of any previous implementation that can send a CTS to MLD1 or a CTS-to-self to occupy the channel on Link 2.

[0205] MLD2 can be a device, system, or method of any previous implementation that can send a TXOP sharing frame to occupy the channel on Link 2.

[0206] MLD2 can be a device, system, or method of any previous implementation that can send a TXOP sharing frame on Link 2 to share a TXOP with other STAs until it obtains a chance to send to MLD1.

[0207] MLD2 can be a device, system, or method of any previous implementation that can send an NSTR coordination indication frame to start NSTR coordination without requesting a response frame from MLD1.

[0208] MLD1 can be a device, system, or method of any previous implementation that can send a frame to reject an NSTR coordination request.

[0209] MLD1 can be a device, system, or method of any previous implementation that cannot return anything to reject an NSTR coordination request.

[0210] As used herein, the term "implementation" is intended to include embodiments, examples, or other forms for practicing the technology described herein without limitation.

[0211] As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. A reference to a single object does not mean "only" unless explicitly stated as such, but rather means "one or more than one."

[0212] Expressions such as "A, B, and / or C" in the present disclosure indicate that any one of A, B, or C, or any combination of items A, B, and C may exist. An expression structure such as one that follows a group of elements listed after "at least one of" indicates that when applicable, at least one of these listed elements exists, including any conceivable combination of any of these listed elements.

[0213] References to the phraseology of "an embodiment", "at least one embodiment", or similar embodiments in the present disclosure indicate that a particular feature, structure, or characteristic described in relation to the embodiment being described is included in at least one embodiment of the present disclosure. Accordingly, these various expressions of embodiments do not necessarily mean all the same embodiments, or a particular embodiment that is different from all the other embodiments described. The expression "embodiment" should be construed to mean that a particular feature, structure, or characteristic of a given embodiment can be combined in any suitable form in one or more of the disclosed devices, systems, or methods.

[0214] The term "set" as used herein means a collection of one or more objects. Thus, for example, a set of objects can include a single object or multiple objects.

[0215] Relative terms such as first and second, top and bottom, etc. in this document are only used to distinguish one entity or action from another entity or action, and do not necessarily require or imply any actual relationship or order between such entities or actions.

[0216] The terms "comprises", "comprising", "has", "having", "includes", "including", "contains", "containing" or any other variation of these terms are intended to include non-exclusive inclusion, so that a process, method, article or apparatus that comprises, has or includes a list of elements does not include only those elements but may also include other elements not expressly listed or inherent to such process, method, article or apparatus. Elements followed by "comprises... a", "has... a", "includes... a", "contains... a" do not preclude the existence of additional identical elements in the process, method, article or apparatus that comprises, has or includes that element, without further limitation.

[0217] As used herein, the terms "approximately", "approximate", "substantially", "essentially" and "about", or any variation thereof, are used for the purpose of describing and explaining minor variations. When used in connection with an event or situation, these terms can mean that the event or situation will definitely occur, and that the event or situation is very likely to occur. When used in connection with a numerical value, these terms can mean a variation range of ±10% or less, such as ±5% or less, ±4% or less, ±3% or less, ±2% or less, ±1% or less, ±0.5% or less, ±0.1% or less, or ±0.05% or less of that numerical value. For example, "substantially" aligned can mean an angular variation range of ±10° or less, such as ±5° or less, ±4° or less, ±3° or less, ±2° or less, ±1° or less, ±0.5° or less, ±0.1° or less, or ±0.05° or less.

[0218] In addition, in this specification, quantities, ratios, and other numerical values may be presented in a range format. Such a range format is used for convenience and simplicity, and includes the numerical values clearly specified as the limits of the range. However, it should be flexibly understood that all individual numerical values or sub-ranges included in this range are also included as if each of these numerical values and sub-ranges were clearly indicated. For example, a ratio within the range of about 1 to about 200 includes the clearly enumerated limit values of about 1 and about 200, but it should also be understood to include individual ratios such as about 2, about 3, about 4, etc., and sub-ranges such as about 10 to about 50, about 20 to about 100, etc.

[0219] As used herein, the term "coupled" is defined as "connected", but it is not necessarily a direct mechanical connection. A device or structure "configured" in a particular form is configured at least in that form, but can also be configured in forms not listed.

[0220] Advantages, merits, problem-solving means, and any (single or plural) elements that give rise to or make more prominent any advantages, merits, or solutions should not be construed as important, necessary, or essential features or elements of the technology described in this specification, or of some or all of the claims.

[0221] Also, in the above disclosure, various features can be grouped together in various embodiments for the purpose of rationalizing the disclosure. The method of this disclosure should not be construed as reflecting an intention that the embodiments described in the claims require more features than those explicitly described in each claim. The subject matter of the present invention can be achieved by less than all the features of a single disclosed embodiment.

[0222] The abstract of this disclosure is presented with the understanding that it is not used to interpret or limit the scope or meaning of the claims.

[0223] Depending on the jurisdiction, it should be understood that there is also a practice of seeking deletion of one or more parts of the present disclosure after filing. Therefore, the reader should refer to the application as filed at the filing date for the original content of the present disclosure. Any deletion of the disclosed content should not be construed as a waiver, forfeiture, or dedication to the public of any subject matter of the application as originally filed.

[0224] The following claims are incorporated into the present disclosure in a state where each claim stands alone as an independent inventive subject matter.

[0225] Although the description in this specification includes many details, these should not be construed as limiting the scope of the present disclosure, but rather as merely exemplifying a part of the presently preferred embodiments. Therefore, the scope of the present disclosure will be understood to fully include other embodiments that would be apparent to those skilled in the art.

[0226] Structural and functional equivalents of elements of embodiments of the present disclosure well-known to those skilled in the art are also clearly incorporated herein by reference and are intended to be included within the scope of the present claims. Further, elements, components, or method steps of the present disclosure are not intended to be generally disclosed as such, whether or not they are explicitly recited in the claims. With respect to the elements of the claims herein, they should not be construed as "means-plus-function" elements unless the element is expressly recited using the phrase "means for". Also, with respect to the elements of the claims herein, they should not be construed as "step-plus-function" elements unless the element is expressly recited using the phrase "step for".

Description of Reference Numerals

[0227] 74 MLD1 76 MLD2 78 STA1 (Link 1) 80 STA2 (Link 2) 82 STA3 (Link 1) 84 STA4 (Link 2) 110 Example Embodiment 112 TXOP acquired by STA1 114 STA1 is transmitting to STA3 116 Dummy frame (from STA4) for reserving a short TXOP 118 STA1 is receiving from STA3 119 CS 120 PPDU (STA4 → STA2) Table 1 UP - AC mapping TIFF0007717953000001.tif62149 Table 2 Example of default parameter settings TIFF0007717953000002.tif31139

Claims

1. An apparatus for wireless communication in a network, comprising: (a) a wireless communication circuit configured as a station (STA) that performs multi-link operation via a plurality of links of a channel and accesses the channel using carrier sense multiple access / collision avoidance (CSMA / CA) to communicate with other wireless stations (STAs) in the network; (b) a processor coupled to the wireless communication circuit to execute a communication protocol; (c) a non-transitory memory storing instructions executable by the processor to communicate with other STAs on the network; wherein (d) the instructions, when executed by the processor, (i) configure a first multi-link device (MLD1) to perform non-simultaneous transmission and reception (NSTR) communication and be the transmitter opportunity (TXOP) owner of a first link (Link 1); (ii) operate the STA within a second multi-link device (MLD2) and access a channel on a second link (Link 2) for transmission to MLD1; (iii) when MLD1 is receiving on Link 1, cause MLD2 to transmit to MLD1 via Link 2 immediately; (iv) when MLD1 is transmitting on Link 1, cause MLD2 to transmit a frame via Link 2 to occupy the channel, and then when MLD1 is receiving on Link 1, cause MLD2 to perform another frame transmission to MLD1; including steps to re-contend for the channel without increasing its contention window (CW) if MLD2 determines not to wait for the time when MLD1 is receiving on Link 1; characterized by the apparatus.

2. MLD2 transmits a dummy frame not containing a data packet to reserve a part of the TXOP to occupy the channel, and then, when MLD1 starts receiving on Link 1 before the end of the TXOP, transmits a frame containing a data packet to MLD1 via Link 2. The apparatus according to claim 1.

3. MLD2 transmits a request to send (RTS) or a multi-user RTS (MU-RTS) incorporating padding to occupy the channel on Link 2. The apparatus according to claim 1.

4. MLD2 transmits a clear to send (CTS) to MLD1 or CTS-to-Self to occupy the channel on Link 2. The apparatus according to claim 1.

5. MLD2 transmits a transmission opportunity (TXOP) sharing frame to occupy a channel on Link 2. The apparatus according to claim 1.

6. MLD2 transmits a transmission opportunity (TXOP) sharing frame to share a TXOP with other STAs on Link 2 until MLD1 starts receiving on Link 1. The apparatus according to claim 1.

7. An apparatus for wireless communication in a network, comprising: (a) a wireless communication circuit as a station (STA) that performs multi-link operation via a plurality of links of a channel to communicate with other wireless stations (STAs) in the network and accesses the channel using carrier sense multiple access / collision avoidance (CSMA / CA); (b) a processor coupled to the wireless communication circuit to execute a communication protocol; (c) a non-transitory memory storing instructions executable by the processor to communicate with other STAs on the network; wherein (d) the instructions, when executed by the processor, (i) associate the STA with a second multi-link device (MLD1) to perform non-simultaneous transmission and reception (NSTR) communication, while associating another STA with a first multi-link device (MLD2); (ii) make MLD1 the transmission opportunity (TXOP) owner of the first link (Link 1); (iii) make the second MLD (MLD2) the TXOP owner of the second link (Link 2) and schedule to transmit to MLD1 on Link 2; (iv) transmit a non-simultaneous transmission and reception (NSTR) adjustment request from MLD2 to MLD1 via Link 2; (v) receive, from MLD1, a response frame indicating whether MLD1 has accepted or rejected the non-simultaneous transmission and reception (NSTR) coordination request when MLD2 requests a response frame from MLD1; (vi) when the non-simultaneous transmission and reception (NSTR) coordination request is accepted, arrange for transmission on both Link 1 and Link 2 by either MLD1 or MLD2, and then execute the transmission; including steps to be executed, MLD2 transmits an NSTR coordination indication frame to start NSTR coordination without requesting a response frame from MLD1. An apparatus characterized by the above.

8. In response to receiving from MLD1 a frame indicating that MLD2 has rejected an NSTR coordination request, MLD2 executes the stop of its current TXOP. The apparatus according to claim 7.

9. Since MLD1 can refrain from returning anything indicating the rejection of the NSTR coordination request, MLD2 does not need to receive the rejection of the NSTR coordination request. The apparatus according to claim 7.

10. A method for performing wireless communication in a network, comprising: a) a wireless communication circuit as a station (STA) executes multi-link operation via a plurality of links of a channel to communicate with other wireless stations (STAs) of the network, and accesses the channel using carrier sense multiple access / collision avoidance (CSMA / CA); b) a first multi-link device (MLD1) that has become the transmitter opportunity (TXOP) owner of a first link (Link 1) executes non-simultaneous transmission and reception (NSTR) communication; c) the STA associated with a second multi-link device (MLD2) accesses the channel on a second link (Link 2) for transmission to MLD1; d) when MLD1 is receiving on Link 1, MLD2 immediately transmits to MLD1 via Link 2; e) when MLD1 is transmitting on Link 1, MLD2 transmits a frame via Link 2 to occupy the channel, and then when MLD1 is receiving on Link 1, MLD2 transmits another frame to MLD1; including wherein, when MLD2 determines not to wait for the time when MLD1 is receiving on Link 1, MLD2 re-contends for the channel without increasing its contention window (CW).

11. MLD2 transmits a dummy frame not including a data packet to reserve a part of the TXOP to occupy the channel, and then, when MLD1 starts receiving on Link 1 before the end of the TXOP, transmits a frame including a data packet to MLD1 via Link 2. The method according to claim 10.

12. MLD2 transmits a request to send (RTS) or a multi-user RTS (MU-RTS) incorporating padding to occupy the channel on Link 2. The method according to claim 10.

13. MLD2 transmits a Clear to Send (CTS) to MLD1, or a CTS-to-Self, to occupy the channel on Link 2. The method according to claim 10.

14. MLD2 transmits a Transmit Opportunity (TXOP) sharing frame to occupy the channel on Link 2. The method according to claim 10.

15. MLD2 transmits a Transmit Opportunity (TXOP) sharing frame to share the TXOP with other STAs on Link 2 until MLD1 starts receiving on Link 1. The method according to claim 10.

Images