Control method employed by a wireless fidelity multi-link device

Abstract

The application provides a control method adopted by a wireless fidelity (Wi-Fi) multi-link device (MLD), comprising: in response to obtaining access right of a first link at a first time point through channel competition, enabling a multi-link coherent operation mode on the first link to perform a frame exchange procedure on the first link by using N spatial streams, wherein N is a positive integer not less than 2; and in response to obtaining access right of a second link at a second time point through channel competition, not allowing the multi-link coherent operation mode to be enabled on the second link, wherein the performance of the second link is lower than that of the first link.

Description

Technical Field

[0001] This invention relates to wireless communication, and more specifically, to a control method employed by a wireless fidelity (Wi-Fi) multi-link device (MLD) to handle multi-link coherent operation. Background Technology

[0002] In Wi-Fi multi-link operation (MLO), multiple links exist between two multi-link devices (MLDs), including an access point (AP) and a non-AP station (STA). These links occupy different radio-frequency (RF) bands. These links can operate independently to increase overall throughput and / or improve connection stability. However, each link has its own capacity depending on several parameters, such as bandwidth (BW), number of spatial streams (NSS), and modulation and coding mechanism (MCS). Furthermore, each link has its own condition depending on several parameters, such as load and interference. The capabilities and conditions of these links can vary significantly. Therefore, it is desirable to optimize the use of these asymmetric links to maximize the overall system performance. Summary of the Invention

[0003] The following summary is illustrative only and is not intended to be limiting in any way. That is, it provides an overview to introduce the concepts, key points, benefits, and advantages of the novel and non-obvious techniques described herein. Selected embodiments are further described in the detailed description below. Therefore, the following summary is neither intended to identify the essential features of the claimed subject matter nor to define the scope of the claimed subject matter.

[0004] One of the objectives of this invention is to provide a control method employed by a Wi-Fi multi-link device (MLD) for handling multi-link coherent operations.

[0005] In a first aspect, the present invention provides a control method employed by a Wi-Fi Multilink Device (MLD), comprising: in response to obtaining access to a first link at a first time point through channel contention, enabling a multilink coherent operation mode on the first link to perform a frame switching procedure on the first link using N spatial streams, wherein N is a positive integer not less than 2; and in response to obtaining access to a second link at a second time point through channel contention, disallowing the enabling of the multilink coherent operation mode on the second link, wherein the performance of the second link is lower than that of the first link.

[0006] In some embodiments, the control method further includes: in response to obtaining access to the second link at the second time point through channel contention, performing a frame switching procedure on the second link using M spatial streams during a first duration, wherein M is a positive integer less than N.

[0007] In some embodiments, M equals 1.

[0008] In some embodiments, the control method further includes: in response to obtaining access to the first link at a third time point through channel contention, performing a frame switching procedure on the first link using L spatial streams during a second duration, wherein L is a positive integer less than N, and the second duration overlaps with the first duration (e.g., partially overlaps).

[0009] In some embodiments, each of M and L is equal to 1.

[0010] In some embodiments, the control method further includes aligning the end time of the first duration with the end time of the second duration.

[0011] In some embodiments, the multi-link coherent operation mode is an enhanced multi-link single-radio EMLSR operation mode.

[0012] In some embodiments, the multi-link coherent operation mode is an enhanced multi-link multi-radio EMLMR operation mode.

[0013] In a second aspect, the present invention provides a control method employed by a Wi-Fi Multilink Device (MLD), comprising: in response to obtaining access to a first link through channel contention, enabling a multilink coherent operation mode on the first link to perform a frame switching procedure on the first link using N spatial streams; and aligning the end time of the frame switching procedure on the first link with the end time of another frame switching procedure performed on a second link occupied by another Wi-Fi device, wherein the performance of the second link is higher than that of the first link, and N is a positive integer not less than 2.

[0014] In some embodiments, the control method further includes: acquiring duration information associated with the other frame switching procedure on the second link before initiating the frame switching procedure on the first link; wherein aligning the end time of the frame switching procedure on the first link with the end time of the other frame switching procedure includes: determining the end time of the frame switching procedure on the first link based on the duration information.

[0015] In some embodiments, the control method further includes: after initiating the frame switching procedure on the first link, acquiring and storing duration information associated with the other frame switching procedure on the second link; wherein aligning the end time of the frame switching procedure on the first link with the end time of the other frame switching procedure includes: determining the end time of the frame switching procedure on the first link based on the duration information.

[0016] In some embodiments, the frame switching procedure on the first link includes one or more frame switching sequences initiated after the duration information is obtained.

[0017] In some embodiments, the last frame exchange sequence in the frame exchange procedure included on the first link contains padding bits.

[0018] In some embodiments, the multi-link coherent operation mode is an enhanced multi-link single-radio EMLSR operation mode.

[0019] In some embodiments, the multi-link coherent operation mode is an enhanced multi-link multi-radio EMLMR operation mode.

[0020] Thirdly, the present invention provides a control method adopted by a Wi-Fi multi-link device (MLD), comprising: maintaining the first back-off counter for one or more time slots before the first back-off counter of the first link reaches zero and the second link is not occupied, in order to wait for the opportunity to access the second link through channel contention, wherein the performance of the second link is higher than that of the first link.

[0021] In response to the second back-off counter of the second link reaching zero during the period during which the first back-off counter is held, a multi-link coherent operation mode is enabled on the second link to perform a frame switching procedure using N spatial streams, where N is a positive integer not less than 2.

[0022] In some embodiments, the multi-link coherent operation mode is an enhanced multi-link single-radio EMLSR operation mode.

[0023] In some embodiments, the multi-link coherent operation mode is an enhanced multi-link multi-radio EMLMR operation mode.

[0024] In some embodiments, the control method further includes: in response to the second link being occupied by another Wi-Fi device during the period in which the first backoff counter is held, resuming the backoff countdown of the first backoff counter.

[0025] In some embodiments, resuming the rollback countdown of the first rollback counter includes: maintaining the first rollback counter for an additional random time slot before resuming the rollback countdown of the first rollback counter.

[0026] These and other objects of the invention will be readily understood by those skilled in the art upon reading the following detailed description of the preferred embodiments illustrated in the accompanying drawings. A detailed description will be given in the following embodiments with reference to the accompanying drawings. Attached Figure Description

[0027] The accompanying drawings (in which the same numerals denote the same components) illustrate embodiments of the present invention. The included drawings are intended to provide a further understanding of embodiments of the present disclosure, and are incorporated in and constitute a part of the present disclosure. The drawings illustrate implementations of embodiments of the present disclosure and, together with the description, serve to explain the principles of the embodiments of the present disclosure. It is understood that the drawings are not necessarily drawn to scale, as some components may be shown out of proportion to actual dimensions in order to clearly illustrate the concepts of the embodiments of the present disclosure.

[0028] Figure 1 This is a schematic diagram of a wireless fidelity (Wi-Fi) system according to an embodiment of the present invention.

[0029] Figure 2 This is a schematic diagram illustrating multi-link coherent operation with unidirectional switching EMLXR features according to an embodiment of the present invention.

[0030] Figure 3 This is a schematic diagram illustrating multi-link coherent operation with unidirectional switching EMLXR (EMLXR priority) and txOnTx alignment features according to an embodiment of the present invention.

[0031] Figure 4 This is a schematic diagram illustrating multi-link coherent operation with txOnRx alignment features according to an embodiment of the present invention.

[0032] Figure 5 This is a schematic diagram of an 802.11ax high-efficiency (HE) frame structure that supports duration information reporting, according to an embodiment of the present invention.

[0033] Figure 6 This is a schematic diagram illustrating multi-link coherent operation with txOnRx alignment and priority channel access features according to an embodiment of the present invention.

[0034] Figure 7 This is a schematic diagram illustrating multi-link coherent operation with multiple txOnRx alignment features according to an embodiment of the present invention.

[0035] Figure 8 This is a schematic diagram illustrating another multi-link coherent operation with multiple txOnRx alignment features according to an embodiment of the present invention.

[0036] In the following detailed description, numerous specific details are set forth for illustrative purposes so that those skilled in the art can more thoroughly understand the embodiments of the invention. However, it will be apparent that one or more embodiments may be practiced without these specific details, and different embodiments may be combined as needed, and should not be limited to the embodiments illustrated in the accompanying drawings. Detailed Implementation

[0037] The following description illustrates preferred embodiments of the present invention and is intended only to exemplify the technical features of the invention, not to limit the scope of the invention. Throughout this specification and claims, certain terms are used to refer to specific elements. Those skilled in the art should understand that manufacturers may use different names for the same element. Therefore, this specification and claims do not distinguish elements by differences in name, but rather by differences in function. The terms "element," "system," and "device" used in this invention can refer to computer-related entities, where the computer can be hardware, software, or a combination of hardware and software. The terms "comprising" and "including" as used in the following description and claims are open-ended terms and should be interpreted as "comprising, but not limited to...". Furthermore, the term "coupled" refers to an indirect or direct electrical connection. Therefore, if a device is described as coupled to another device, it means that the device can be directly electrically connected to the other device, or indirectly electrically connected to the other device through other devices or connection means.

[0038] Unless otherwise indicated, the corresponding numbers and symbols in the various figures generally refer to the corresponding parts. The figures are drawn to clearly illustrate the relevant parts of the embodiments and are not necessarily drawn to scale.

[0039] The terms "basically" or "roughly" as used in this document mean that, within an acceptable range, a person skilled in the art can solve the technical problem to be solved and basically achieve the desired technical effect. For example, "roughly equal to" means a method that a person skilled in the art can accept with a certain margin of error from "exactly equal to" without affecting the correctness of the result.

[0040] Figure 1This is a schematic diagram of a Wi-Fi system 100 according to an embodiment of the present invention. For simplicity, it is assumed that the Wi-Fi system 100 includes two multi-link devices (MLDs) 102 and 104, wherein one of MLDs 102 and 104 can be an access point (AP), and the other of MLDs 102 and 104 can be a non-AP site (STA). For example, MLD 102 acts as an AP MLD, while MLD 104 acts as a non-AP MLD. As another example, MLD 102 acts as a non-AP MLD, while MLD 104 acts as an AP MLD. In some embodiments, the AP MLD may have X links L1-L X Furthermore, AP MLD can be accessed via Y links L1-L Y Communicating with non-AP MLDs, where X and Y are positive integers, Y is not less than 2, and X is not less than Y (i.e., X ≥ Y ≥ 2, where X and Y are both positive integers). Figure 1 In the illustrated embodiment, MLD 102 includes processing circuitry 112, multiple transceivers (labeled "TX / RX" in the figure) 114_1-114_i, and multiple antennas 116_1-116_i, where i is a positive integer and not less than 2. Similarly, MLD 104 includes processing circuitry 122, multiple transceivers (labeled "TX / RX" in the figure) 124_1-124_j, and multiple antennas 126_1-126_j, where j is a positive integer not less than 2 (that is, i and j are positive integers ≥ 2; for example, in some examples, i=j=2, in others, i=j=4, in still others, i=j=8, etc.; specifically, the present invention does not limit this). In some embodiments where MLD 102 acts as an AP MLD and MLD 104 acts as a non-AP MLD, i can be equal to X (e.g., i=X=2) and j can be equal to Y (e.g., j=Y=2), where X≥Y (e.g., X=Y).

[0041] In another scenario, where MLD 102 acts as a non-AP MLD and MLD 104 acts as an AP MLD, i can be equal to Y, and j can be equal to X, where X ≥ Y. The transceivers 114_1-114_i of MLD 102 can connect to multiple links L1-L. Y Communicates with transceivers 114_1-114_j of MLD 104. In this embodiment, link L1-L Y Each of these can be defined by a channel (or interchangeably, a "channel") within a frequency band. For example, link L1-L YThis can include different channels in the same frequency band (e.g., A-band (2.4 GHz band), G-band (5 GHz band), or 6 GHz band) and / or channels in different frequency bands (e.g., A-band (2.4 GHz band) and G-band (5 GHz) band). In other words, the multi-link coherent operation proposed in this invention can be applied to any asymmetric multiple links, such as A+G (two links), A+A+G (three links), A+A+A+G (four links), A+A+G+G (four links), A+A+A+G+G (five links), etc. To better understand the technical features of the multi-link coherent operation proposed in this invention, it is assumed below that the asymmetric multiple links include one link located in the 5 GHz band and one link located in the 2.4 GHz band. In some embodiments, the number of spatial streams is related to the number of antennas; for example, the number of spatial streams ≤ the number of antennas.

[0042] By way of example and not limitation, processing circuits 112 / 122 are arranged to execute a control method for processing the proposed multi-link coherent operation. For example, processing circuit 112 of MLD 102 may be implemented by a processor operating according to a plurality of control registers (CRs) 118, and processing circuit 122 of MLD 104 may be implemented by a processor operating according to a plurality of control registers (CRs) 128. In some embodiments of the invention, one or both of MLDs 102 and 104 may be a simultaneous transmit-receive (STR) MLD supporting a multi-link coherent operation mode, for example, the multi-link coherent operation mode may be an enhanced multi-link single-radio (EMLSR) operation mode or an enhanced multi-link multi-radio (EMLMR) operation mode. Understandably, the difference between EMLSR and EMLMR operating modes lies in the following: For EMLSR (Enhanced Multi-Link Single Radio) operating mode, the MLD allows transmission on only a single link during enhanced multi-link operation (e.g., for a 4x4 MIMO system, all four spatial streams are on a high-performance link); for EMLMR operating mode, the MLD allows transmission on two or more links during enhanced multi-link operation (e.g., for a 4x4 MIMO system, three spatial streams are on a high-performance link, and one spatial stream is on a low-performance link). In some embodiments of the invention, one or both of MLDs 102 and 104 may be a non-simultaneous transmit-receive (NSTR) MLD that supports multi-link coherent operating modes (e.g., EMLSR or EMLMR). However, these are for illustrative purposes only and do not imply limitation of the invention. Further details of the multi-link coherent operation proposed in this invention are provided below with reference to the accompanying drawings.

[0043] Figure 2 This is a schematic diagram illustrating multi-link coherent operation with a one-way switch EMLXR according to an embodiment of the present invention. The term "EMLXR" is intended to encompass both EMLSR and EMLMR; that is, the term "EMLXR" can be used to refer to either EMLSR or EMLMR, and is a collective term for both. Links L1-L available between MLDs 102 and 104 are shown.YAsymmetric links can have different link capabilities (e.g., BW, MCS, and / or NSS) and conditions (e.g., load and / or interference). Therefore, if Y=2, the asymmetric link can include a first link and a second link, for example, the first link has higher performance (i.e., higher effective link throughput) than the second link. Understandably, comparing the first and second links, the second link's performance is lower than the first link's performance; therefore, the second link can be considered a low-performance link, and the first link can be considered a high-performance link. For example, if Y=4, the asymmetric link can include a first link, a second link, a third link, and a fourth link. Similarly, the performance differences of these Y links can be determined based on their respective link capabilities. For example, in one example, the performance of these Y links can be ranked from highest to lowest as follows: the first link performs better than the third link, the third link performs better than the fourth link, and the fourth link performs better than the second link. For example, the first link (optionally, and the third link) can be considered a high-performance link, and the second link (optionally, and the fourth link) can be considered a low-performance link. However, enabling EMLXR operation mode on low-performance links will affect channel access opportunities on high-performance links. To address this issue, this invention proposes enabling EMLXR operation mode only on high-performance links. In embodiments of this invention, multi-link coherent operation mode refers to an operation mode in which MLD can use more spatial streams than the preset number of spatial streams corresponding to conventional multi-link operation modes for transmission on the corresponding links. For example, in some embodiments (e.g., in cases where the high-performance link is not occupied by other MLDs), if an MLD first obtains access to the high-performance link (which can also be interchangeably described as "right of use" or "right of access"), it can use more space streams than the preset number of space streams corresponding to the regular multi-link operation (MLO) mode (i.e., enable EMLXR operation mode to perform EMLXR transmission). And, if an MLD first obtains access to a low-performance link, it is not allowed to enable EMLXR operation on the low-performance link (i.e., it is not allowed to use more space streams than the preset number of space streams corresponding to the regular multi-link operation mode for transmission on the low-performance link), but instead uses space streams no greater than the preset number of space streams corresponding to the regular multi-link operation (MLO) mode, so that when the MLD may obtain access to the high-performance link in the future, it can use more space streams, thereby improving transmission efficiency.For example, in one example of this embodiment (when the high-performance link is not occupied by other MLDs), for the case of i=j=Y=2, the preset spatial flow on a single link (corresponding to the conventional multi-link operation MLO mode) is 1 spatial flow (1SS). When the EMLXR operation mode is enabled (enabled only on the high-performance link), the spatial flow used is 2 spatial flows (2SS>preset spatial flow 1SS). When the MLD first obtains access to the low-performance link, it uses 1SS for transmission on the low-performance link. For example, in another example of this embodiment (when the high-performance link is not occupied by other MLDs), for the case of i=j=4 and Y=2, the preset spatial flow on a single link (corresponding to the conventional multi-link operation MLO mode) is 2SS. When the EMLXR operation mode is enabled (only enabled on the high-performance link), the spatial flow used can be 3SS or 4SS (which is greater than the preset spatial flow 2SS corresponding to the conventional multi-link operation mode, for example, preferably 4SS). When the MLD first obtains the access right of the low-performance link, it can use 1SS or 2SS (not greater than the preset spatial flow 2SS corresponding to the conventional multi-link operation mode) for transmission on the low-performance link (for example, preferably 1SS), and is not allowed to enable the EMLXR operation mode (i.e., is not allowed to use 3SS or 4SS for transmission). For example, in another example of this embodiment (when the high-performance link is not occupied by other MLDs), for the case of i=j=4, Y=4, the preset spatial flow (corresponding to the conventional multi-link operation mode) on a single link is 1SS. When the EMLXR operation mode is enabled (enabled only on the high-performance link), the spatial flow used can be 2SS, 3SS, or 4SS (which is greater than the preset spatial flow 1SS, for example, preferably 4SS). When an MLD first obtains access to a low-performance link, it can use one spatial flow (1SS) for transmission on the low-performance link, but is not allowed to enable the EMLXR operation mode (i.e., is not allowed to use 2SS, 3SS, or 4SS for transmission). The above examples are only illustrative, and the present invention is not limited to these examples. For ease of explanation, the following example illustrates the case where the number of transmit and receive antennas is 2 and the number of links is 2.

[0044] For ease of explanation and understanding, assume that the MLD (e.g., MLD 102 or 104) has two antennas, one link in the 5 GHz band (a high-performance link L_HI with high throughput) and one link in the 2.4 GHz band (a low-performance link L_LO with lower throughput). For a typical (or interchangeably described as "conventional") multi-link operation (MLO) mode (which does not have EMLXR), as... Figure 2As shown at the top (the corresponding section labeled "MLO"), after an MLD gains access to a high-performance link L_HI through channel contention, it performs a frame exchange process on the high-performance link L_HI using the default / preset spatial stream (e.g., a single spatial stream, i.e., 1ss). After gaining access to a low-performance link L_LO through channel contention, it performs a frame exchange process on the low-performance link L_LO using the default spatial stream (e.g., a single spatial stream, i.e., 1ss).

[0045] Regarding EMLXR operations that do not impose constraints (or can be interchangeably described as "restrictions") on link selection, such as... Figure 2 The middle section (the corresponding section labeled "EMLXR") shows that after an MLD gains access to a high-performance link L_HI through channel contention, it enables (or can be interchangeably described as "started" or "enabled") the EMLXR operating mode on the high-performance link L_HI to perform frame switching procedures using multiple spatial streams (e.g., 2ss, which are more than the preset spatial streams). Similarly, after gaining access to a low-performance link L_LO through channel contention, it enables the EMLXR operating mode on the low-performance link L_LO to perform frame switching procedures using multiple spatial streams (e.g., 2ss, which are more than the preset spatial streams). In other words, the EMLXR operating mode is allowed on the low-performance link L_LO. Therefore, in Figure 2 In the example shown in the middle section, when MLD obtains access to a low-performance link L_LO before obtaining access to a high-performance link L_HI, MLD enables EMLXR mode on the low-performance link L_LO without considering channel access opportunities on the high-performance link L_HI. Consequently, when MLD subsequently obtains access to the high-performance link L_HI, it is unable to perform EMLXR operations on the high-performance link L_HI. Since frame switching cannot be performed on the high-performance link L_HI during the period when MLD performs EMLXR operations on the low-performance link L_LO, a performance loss occurs. To improve system performance, this invention proposes a one-way switch EMLXR operation restricted to high-performance links only (preferred EMLXR operation, meaning that EMLXR operations are preferentially enabled on high-performance links and not allowed on low-performance links).

[0046] Regarding the EMLXR operation with link selection constraints proposed in this invention (also known as "one-way switching EMLXR operation"), as follows: Figure 2 As shown at the bottom (the corresponding part labeled "EMLXR - One-Way Switching"), when MLD 102 / 104 obtains access to the high-performance link L_HI through channel contention, it enables the EMLXR operating mode (also interchangeably described as "EMLXR mode" in this embodiment) on the high-performance link L_HI to perform frame switching procedures using multiple spatial streams (e.g., 2ss, which are more than the preset spatial streams). Furthermore, when it obtains access to the low-performance link L_LO through channel contention, it blocks the enabling of the EMLXR mode on the low-performance link L_LO. In other words, enabling the EMLXR mode on the low-performance link L_LO is not allowed. Figure 2 In the example shown at the bottom, after MLD 102 / 104 obtains access to the low-performance link L_LO through channel contention at time point T1, it performs a frame switching procedure on the low-performance link L_LO using a single spatial stream (i.e., 1ss, no greater than a preset spatial stream) for a duration (e.g., the transmission opportunity (TXOP) duration) P1. Similarly, after MLD 102 / 104 obtains access to the high-performance link L_HI through channel contention at time point T2, it performs a frame switching procedure on the high-performance link L_HI using a single spatial stream (i.e., 1ss) for a duration (e.g., the TXOP duration) P2. Since EMLSR / EMLMR mode is not enabled on the low-performance link L_LO, MLD 102 / 104 improves / enhances the channel access opportunity for the high-performance link L_HI. Specifically, the throughput of the high-performance link using one spatial stream and the low-performance link using one spatial stream is higher than the throughput of the low-performance link using two spatial streams.

[0047] As an example and not a limitation, the processing circuits 112 / 122 are arranged to handle unidirectional switching EMLXR operations (preferred EMLXR operations). For example, assume there are four asymmetric links L1-L Y(Y=4), control registers 118 / 128 include a 16-bit control register CR_PER_LINK_EMLSR_EMLMR[0:15]. This 16-bit control register CR_PER_LINK_EMLSR_EMLMR[0:15] records two bits for each link, specifying whether a particular link is allowed to perform EMLSR / EMLMR operations if it gains a transmission opportunity through channel contention. More specifically, the 16-bit control register CR_PER_LINK_EMLSR_EMLMR[0:15] specifies the priority of each link, where priority 3>2>1>0 (0: indicates that EMLSR / EMLMR operations are not allowed). An example of the 16-bit control register CR_PER_LINK_EMLSR_EMLMR[0:15] is shown below.

[0048]

[0049] Therefore, regarding EMLSR operations, links 1 and 2 can perform EMLSR operations, with link 2 having higher priority than link 1. Furthermore, EMLSR operations are not allowed on link 0. Similarly, regarding EMLMR operations, links 0 and 2 can perform EMLMR operations, with link 2 having higher priority than link 0. EMLMR operations are not allowed on link 1.

[0050] like Figure 2As shown, the end time of duration (or interchangeably, "duration") P1 (i.e., the end time of the frame switching procedure on the low-performance link L_LO) is not aligned with the end time of duration P2 (i.e., the end time of the frame switching procedure on the high-performance link L_HI). The following scenario is possible: while the high-performance link L_HI is still occupied by MLD 102 / 104 for frame switching, MLD 102 / 104 gains access to the low-performance link L_LO during the backoff procedure (or interchangeably, "backoff process") after the end time of duration P2, and then initiates another frame switching procedure (non-EMLXR transmission) on the low-performance link L_LO using a single spatial stream. Therefore, non-EMLXR transmission on the low-performance link L_LO will affect the opportunity for EMLXR transmission (using more spatial streams for transmission) on the high-performance link L_HI. To address this issue, the present invention also proposes aligning the end time of non-EMLXR transmissions on the low-performance link L_LO with the end time of non-EMLXR transmissions on the high-performance link L_HI, wherein the high-performance link L_HI and the low-performance link L_LO are occupied by the same MLD 102 / 104.

[0051] Figure 3 This is a schematic diagram illustrating multi-link coherent operation with unidirectional switching EMLXR (preferred EMLXR) and txOnTx (transmission stacking transmission, which is for situations where high-performance links and low-performance links are occupied by the same MLD) alignment, according to an embodiment of the present invention. In this embodiment, the EMLXR operation has restrictions on link selection (i.e., unidirectional switching EMLXR operation can only be enabled on high-performance links), and the non-EMLXR operation has restrictions on the end time of non-EMLXR transmissions. Figure 3As shown, when MLD 102 / 104 obtains access to the low-performance link L_LO through channel contention at time point T1', it does not allow EMLXR mode to be enabled on the low-performance link L_LO for frame switching procedures executed on the low-performance link L_LO. Conversely, after MLD 102 / 104 obtains access to the low-performance link L_LO through channel contention at time point T1', it uses a single spatial stream (i.e., 1ss) to execute frame switching procedures on the low-performance link L_LO (corresponding to "non-EMLXR operation", "non-EMLXR", or "non-EMLXR frame switching procedure"). Therefore, when the low-performance link L_LO is used for frame switching, and MLD 102 / 104 obtains access to the high-performance link L_HI through channel contention at time point T2', it is allowed to initiate a frame switching procedure on the high-performance link L_HI using a single spatial stream (i.e., 1ss).

[0052] like Figure 3 As shown, MLD 102 / 104 performs a frame switching procedure on the high-performance link L_LO using a single spatial stream during a duration (e.g., the TXOP duration) P2'. In this embodiment, MLD 102 / 104 further controls the frame switching procedure on the low-performance link L_LO to align the end time of duration P1' (i.e., the end time of the frame switching procedure on the low-performance link L_LO) with the end time of duration P2' (i.e., the end time of the frame switching procedure on the high-performance link L_HI). Since the end time of the frame switching procedure on the low-performance link L_LO occupied by MLD 102 / 104 coincides with the end time of the frame switching procedure on the same low-performance link L_LO occupied by MLD 102 / 104, MLD 102 / 104 improves / enhances the opportunity to perform EMLXR operation on the high-performance link L_HI after the high-performance link L_HI becomes idle.

[0053] For example, but not limited to, processing circuits 112 / 122 are arranged to process unidirectional switching EMLXR operations with txOnTx alignment (preferred EMLXR operations). For example, assume there are 4 asymmetric links L1-L Y(Y=4), control registers 118 / 128 may include a 4-bit control register CR_TXONTX_COHERENT_EMLXR[0:3]. This 4-bit control register CR_TXONTX_COHERENT_EMLXR[0:3] has one bit for each link record, where a value of "0" indicates that MLD cannot perform txOnTx alignment, and a value of "1" indicates that MLD can perform txOnTx alignment on low-priority links (e.g., low-performance links with priority > 0) to align the end time of transmissions on low-priority links with the end time of transmissions on higher-priority links (e.g., high-performance links with the highest priority).

[0054] Based on the unidirectional switching EMLXR operation with txOnTx alignment (preferred EMLXR operation), the end time of the non-EMLXR frame switching procedure performed on the low-performance link L_LO occupied by MLD102 / 104 is aligned with the end time of the (EMLXR / non-EMLXR) frame switching procedure performed on the high-performance link L_HI occupied by the same MLD102 / 104. (For example, for a 4*4 MIMO system, during duration P1', one spatial stream can be used for a non-EMLXR frame switching procedure on the low-performance link L_LO, and during duration P2', three spatial streams can be used for an EMLXR frame switching procedure on the high-performance link L_HO; and for a 2*2 MIMO system...) In a MIMO system, during duration P1', a single spatial stream can be used for non-EMLXR frame switching on the low-performance link L_LO, and during duration P2', a single spatial stream can be used for non-EMLXR frame switching on the high-performance link L_HO, increasing the opportunity for EMLXR operation on the high-performance link L_HI. The same concept can be applied to high-performance links L_HI and low-performance links L_LO occupied by different Wi-Fi devices to ensure optimal transmission efficiency for each MLD. For example, in the case of Y=2, if an MLD obtains access to the low-performance link but finds that the high-performance link is already occupied by another MLD, then that MLD can use more spatial streams than the preset number (e.g., preferably, the maximum supported number of spatial streams, such as 2SS for a 2x2 MIMO system, or 4SS for a 4x4 MIMO system, etc.) for EMLXR transmission on the low-performance link. For example, by aligning the end time of the EMLXR frame switching procedure performed on the low-performance link L_LO occupied by the first Wi-Fi device (e.g., one of MLD 102 and 104) with the end time of the frame switching procedure performed on the high-performance link L_HI occupied by the second Wi-Fi device (e.g., the other of MLD 102 and 104), more opportunities to perform EMLXR operations on the high-performance link L_HI can be obtained.

[0055] Figure 4 This is a schematic diagram illustrating multi-link coherent operation with txOnRx (transmit stack receive, for situations where high-performance links and low-performance links are occupied by different MLDs) alignment features / functions according to an embodiment of the present invention. In this embodiment, the EMLXR operation has a limitation on the end time of the transmission. Figure 4As shown, when the first Wi-Fi device (e.g., one of MLDs 102 and 104) wins access to the low-performance link L_LO at time point T3 through channel contention, the high-performance link L_HI has already been occupied by the second Wi-Fi device (e.g., the other of MLDs 102 and 104) (labeled "Others" in the figure to indicate that the corresponding link is occupied by other devices). Therefore, after the first Wi-Fi device (e.g., one of MLDs 102 and 104) wins access to the low-performance link L_LO at time point T3 through channel contention, it enables EMLXR mode on the low-performance link L_LO to perform frame switching procedures using multiple spatial streams (e.g., 2ss, which is more than the preset spatial streams).

[0056] For example, a first Wi-Fi device (e.g., one of MLDs 102 and 104) can send frames / packets to a second Wi-Fi device (e.g., the other of MLDs 102 and 104) via a low-performance link L_LO, while the second Wi-Fi device (e.g., the other of MLDs 102 and 104) can send frames / packets to the first Wi-Fi device (e.g., one of MLDs 102 and 104) via a high-performance link L_LO. In this embodiment, the first Wi-Fi device (e.g., MLDs 102 / 104) further controls the frame switching procedure on the low-performance link L_LO to align the end time of duration P3 (i.e., the end time of the frame switching procedure on the low-performance link L_LO) with the end time of duration P4 (i.e., the end time of the frame switching procedure on the high-performance link L_HI). Because the end time of the frame switching procedure on the low-performance link L_LO occupied by the first Wi-Fi device (e.g., one of MLD 102 and 104) coincides (aligns) with the end time of the frame switching procedure on the high-performance link L_HI occupied by the second Wi-Fi device (e.g., the other of MLD 102 and 104), the first Wi-Fi device (e.g., one of MLD 102 and 104) improves its opportunity to perform EMLXR operation on the high-performance link L_HI after the high-performance link L_HI becomes idle.

[0057] Similarly, when the first Wi-Fi device (e.g., one of MLDs 102 and 104) wins access to the low-performance link L_LO at time point T5 through channel contention, the high-performance link L_HI has already been occupied by the second Wi-Fi device (e.g., the other of MLDs 102 and 104). Therefore, after the first Wi-Fi device (e.g., one of MLDs 102 and 104) wins access to the low-performance link L_LO through channel contention at time point T5, it can enable EMLXR mode on the low-performance link L_LO to perform frame switching procedures using multiple spatial streams (e.g., 2ss, which is more than the preset spatial streams). In this embodiment, the first Wi-Fi device (e.g., MLD 102 / 104) further controls the frame switching procedure on the low-performance link L_LO to align the end time of duration P5 (i.e., the end time of the frame switching procedure on the low-performance link L_LO) with the end time of duration P6 (i.e., the end time of the frame switching procedure on the high-performance link L_HI). Since the end time of the frame switching procedure on the low-performance link L_LO occupied by the first Wi-Fi device (e.g., one of MLD 102 and 104) is consistent / aligned with the end time of the frame switching procedure on the high-performance link L_HI occupied by the second Wi-Fi device (e.g., the other of MLD 102 and 104), the first Wi-Fi device (e.g., MLD 102 or 104) improves the opportunity to perform EMLXR operation on the high-performance link L_HI after the high-performance link L_HI becomes idle.

[0058] The high-performance channel L_HI occupied by the second Wi-Fi device (e.g., one of MLD 102 and 104) is used to transmit frames / packets to the first Wi-Fi device (e.g., the other of MLD 102 and 104). The duration information (or interchangeably, “duration information”) associated with the frame switching procedure on the high-performance link L_HI can be obtained before initiating the frame switching procedure on the low-performance link L_LO. Therefore, the duration information associated with the frame switching procedure on the high-performance link L_HI occupied by the second Wi-Fi device can be used to determine the end time of the frame switching procedure on the low-performance link L_LO. For example, the duration information associated with the frame switching procedure on the high-performance link L_HI occupied by the second Wi-Fi device (e.g., one of MLD 102 and 104) can be reported in the preamble of frames / packets transmitted to the first Wi-Fi device (e.g., the other of MLD 102 and 104). Figure 5This is a schematic diagram of an 802.11ax high-efficiency (HE) frame structure supporting duration information reporting, according to an embodiment of the present invention. In IEEE 802.11ax, a HE Packet Protocol Data Unit (PPDU) may have a legacy preamble 502, an HE preamble 504, data 506, and a packet extension (PE) field 508. Regarding the legacy preamble 502, it may include a legacy short training field (L-STF), a legacy long training field (L-LTF), and a legacy signal field (L-SIG). Regarding the HE preamble 504, it may include a repeated L-SIG (RL-SIG) field, an HE-SIG-A field, an HE-STF field, and an HE-LTF field. Information about L_LENGTH (understandably, L_LEGNTH is a proper noun in the Wi-Fi standard, one of its main functions being to describe the length of Wi-Fi PPDU packets) or PPDU duration can be reported as early as possible. For example, it can be reported when L-SIG is detected, or it can be reported at any time after L-SIG is detected, depending on the actual hardware implementation.

[0059] As an example and not a limitation, the processing circuits 112 / 122 are arranged to handle txOnRx alignment. For example, assume there are 4 asymmetric links L1-L Y(Y=4), control registers 118 / 128 may include a 4-bit control register CR_TXONRX_COHERENT_EMLXR[0:3], a 16-bit control register CR_TXONRX_SNG_DURATION_OFFSET_COHERENT_EXMLXR[0:15], and a 16-bit control register CR_TXONRX_DURATION_THRESHOLD_COHERENT_EXMLLXR[0:15]. The 4-bit control register CR_TXONRX_COHERENT_EMLXR[0:3] has one bit for each link record, where a value of "0" indicates that the MLD cannot perform txonRx alignment for this link, and a value of "1" indicates that the MLD can perform txOnRx alignment for this link. The 16-bit control register CR_TXONRX_SNG_DURATION_OFFSET_COHERENT_EXMLXR[0:15] is for RXTIME (e.g., ...). The offset OFS of TXTIME is recorded, where TXTIME = RXTIME - OFS. TXTIME is the duration of the frame switching procedure on the low-performance link, and RXTIME is the duration of the frame switching procedure on the high-performance link. Therefore, aligning the end time of the frame switching procedure on the low-performance link with the end time of the frame switching procedure on the high-performance link can make the end time of the frame switching procedure on the low-performance link exactly the same as the end time of the frame switching procedure on the high-performance link (i.e., OFS = 0), or can make the end time of the frame switching procedure on the low-performance link deviate from the end time of the frame switching procedure on the high-performance link by a fixed offset (i.e., OFS ≠ 0). The 16-bit control register CR_TXONRX_DURATION_THRESHOLD_COHERENT_EXMLLXR[0:15] records the threshold TH to determine whether to perform txOnRx alignment. For example, if RXTIME > TH, MLD can perform txOnRx alignment on the link. Otherwise, txOnRx alignment is not performed on the link.

[0060] The txOnRx alignment feature can be used in conjunction with other features to further improve system performance. Figure 6This is a schematic diagram illustrating multi-link coherent operation with txOnRx alignment and priority channel access according to an embodiment of the present invention. In this embodiment, the EMLXR operation has a constraint on the transmission end time, and a backoff counter for low-performance links is maintained to wait for access opportunities on high-performance links. Figure 6 As shown, the MLD 102 / 104 uses a backoff counter CNT_HI during the backoff procedure (which can also be interchangeably described as a "backoff process") of the high-performance link L_HI, and another backoff counter CNT_LO during the backoff procedure of the low-performance link L_LO. When the backoff counter CNT_HI reaches 0 and the high-performance link L_HI is not occupied by other Wi-Fi devices (i.e., the high-performance link L_HI is idle), the MLD 102 / 104 can obtain access to the high-performance link L_HI through channel contention.

[0061] Similarly, when the backoff counter CNT_LO reaches 0 and the low-performance link L_LO is not occupied by other Wi-Fi devices (i.e., the low-performance link L_LO is idle), the MLD 102 / 104 can obtain access to the low-performance link L_LO through channel contention. Figure 6 As shown in the left section, the backoff counter CNT_HI reaches 1 at time T10 and 0 after one time slot ST if the high-performance link L_HI remains idle. Therefore, assuming both the high-performance link L_HI and the low-performance link L_LO are idle, the backoff counter CNT_HI reaches 0 at time T11 (before time T12 when the backoff counter CNT_LO reaches 0), while the backoff counter CNT_LO reaches 0 at time T12. Since the high-performance link L_HI is unoccupied at time T11, after gaining access to the high-performance link L_HI through channel contention at time T11, the MLD 102 / 104 can enable EMLXR mode on the high-performance link L_HI to perform frame switching procedures using multiple spatial streams (e.g., 2ss).

[0062] like Figure 6As shown in the middle section, the backoff counter CNT_HI reaches 3 at time T21, and the backoff counter CNT_LO reaches 1 at time T21. If the low-performance link L_LO remains idle and the backoff counter CNT_LO is not maintained by the priority channel access mechanism proposed in this invention, then the backoff counter CNT_LO will become 0 at time T22. That is, the backoff counter CNT_LO will become 0 after one time slot ST. Since the backoff counter CNT_HI reaches 2 at time T22, MLD 102 / 104 cannot yet obtain access to the high-performance link L_HI through channel contention. If MLD 102 / 104 acquires access to the low-performance link L_LO at time point T22, before the backoff counter CNT_HI reaches 0 at time point T23, then MLD 102 / 104 can enable EMLXR mode on the low-performance link L_LO. This prevents MLD 102 / 104 from performing EMLXR operations on the high-performance link L_HI when it acquires access to the high-performance link L_HI at a later time point T23. To address this issue, this invention proposes holding the backoff counter CNT_LO to wait for an opportunity to access the high-performance link L_HI. Specifically, before the backoff counter CNT_LO reaches 0 and the high-performance link L_HI is not occupied, MLD 102 / 104 can hold the backoff counter CNT_LO for one or more time slots to wait for an opportunity to access the high-performance link L_HI through channel contention.

[0063] like Figure 6 As shown in the middle section, the backoff counter CNT_LO is maintained during time period P61, and the backoff counter CNT_HI reaches 0 during time period P61. Therefore, when the backoff counter CNT_HI reaches 0 at time point T23, the backoff counter CNT_LO remains at a non-zero value (e.g., 1). Thus, after MLD 102 / 104 gains access to the high-performance link L_HI at time point T23 during time period P61 when the backoff counter CNT_LO is maintained, it can enable EMLXR mode on the high-performance link L_HI by using multiple spatial streams (e.g., 2ss). It should be noted that because the backoff counter CNT_LO remains at a non-zero value, another Wi-Fi device may gain access to the low-performance link L_LO during time period P61 and use the low-performance link L_LO for frame switching. In simple terms, when the high-performance link is not yet occupied, the MLD102 / 104 will appropriately delay the channel access opportunity of the low-performance link in order to try to obtain the access right of the high-performance link first.

[0064] like Figure 6As shown in the right half, the backoff counter CNT_HI reaches 3 at time T31, and the backoff counter CNT_LO reaches 1 at time T31. If the backoff counter CNT_LO is not maintained by the proposed priority channel access mechanism, then if the low-performance link L_LO remains idle, the backoff counter CNT_LO will reach 0 at time T32. If the backoff counter CNT_HI reaches 2 at time T32, then MLD 102 / 104 cannot yet gain access to the high-performance link L_HI through channel contention. To solve this problem, the present invention proposes maintaining the backoff counter CNT_LO to wait for an opportunity to access the high-performance link L_HI. In this example, before the backoff counter CNT_HI reaches 0, another Wi-Fi device occupies the high-performance link L_HI during the time period P62 during which the backoff counter CNT_LO is maintained. In response to the high-performance link L_HI being occupied by another Wi-Fi device (labeled "Others" in the diagram), the MLD 102 / 104 resumes the backoff countdown of the backoff counter CNT_LO, thereby allowing channel access opportunities for the low-performance link L_LO. For example, the backoff counter CNT_LO reaches 0 at time T33. Therefore, after the MLD 102 / 104 gains access to the low-performance link L_LO at time T33, it can enable EMLXR mode on the low-performance link L_LO by using multiple spatial streams (e.g., 2ss). In short, the MLD 102 / 104 only accesses (or uses, or accesses) the low-performance link when the high-performance link is occupied / busy.

[0065] When multiple MLDs employ the priority channel access mechanism proposed in this invention, it is possible that the backoff counter CNT_LO of two or more MLDs may be maintained at the same non-zero value (e.g., 1) when the high-performance link L_HI is occupied by another Wi-Fi device. A conflict may occur when these MLDs' backoff counters CNT_LO resume their respective backoff countdowns at the same time. To address this issue, this invention further proposes introducing an extra random slot time before resuming the backoff countdown of the backoff counter CNT_LO. That is, during the period P62 during which the backoff counter CNT_LO is maintained, before resuming the backoff countdown of the backoff counter CNT_LO in response to the high-performance link L_HI being occupied by another Wi-Fi device, MLDs 102 / 104 can maintain the backoff counter CNT_LO for an extra random slot time. For example, MLDs 102 / 104 can randomly extend the period P62 by maintaining the backoff counter CNT_LO for an extra random slot time introduced after time point T33. In this way, the intentional introduction of randomness (i.e., the introduction of additional random time slots) can mitigate / reduce conflicts.

[0066] As an example and not a limitation, the processing circuits 112 / 122 are arranged to handle channel access with priority. For example, assume there are four asymmetric links L1-L Y (Y=4), control registers 118 / 128 may include an 8-bit control register CR_WAITSLOT_PIFS_COHERENT_EMLXR[0:7] and a 4-bit control register CR_EXTRA_RANDOM_SLOT_COHERENT_EMLXR[0:3]. The 8-bit control register CR_WAITSLOT_PIFS_COHERENT_EMLXR[0:7] records two bits for each link, where a value of "0" indicates that the link does not have a waiting slot and PIFS (Point Coordination Function Interframe Space), a value of "1" indicates that the link has a waiting slot, a value of "2" indicates that the link has PIFS, and a value of "3" indicates that it is not applicable. The 4-bit control register CR_EXTRA_RANDOM_SLOT_COHERENT_EMLXR[0:3] records one bit for each link, where a value of "0" indicates that no additional random slots are introduced, and a value of "1" indicates that additional random slots are introduced.

[0067] about Figure 4The aforementioned txOnRx alignment, by aligning the end time of the frame switching procedure on the low-performance link L_LO occupied by one Wi-Fi device with the end time of the frame switching procedure on the high-performance link L_HI occupied by another Wi-Fi device, improves the opportunity for EMLXR operation on the high-performance link L_HI (i.e., increases the chance of performing EMLXR operation on the high-performance link L_HI). The duration information associated with the frame switching procedure on the high-performance link L_HI can be obtained before the frame switching procedure on the low-performance link L_LO begins. However, in some scenarios, the duration information associated with the frame switching procedure on the high-performance link L_HI may be available after the frame switching procedure on the low-performance link L_LO has started. This invention proposes that, after obtaining the duration information associated with the frame switching procedure on the high-performance link L_HI, the duration information be stored, and txOnRx alignment be implemented using one or more frame switching sequences started after obtaining the duration information. For example, a frame exchange sequence may include one or more frames / packets exchanged between two Wi-Fi devices (e.g., MLD 102 and 104).

[0068] Figure 7 This is a schematic diagram of multi-link coherent operation with multiple txOnRx alignments according to an embodiment of the present invention. In this embodiment, the EMLXR operation has a limitation on the end time of transmission. Figure 7 As shown, when a first Wi-Fi device (e.g., one of MLD 102 and 104) gains access to the low-performance link L_LO through channel contention, the high-performance channel L_HI is occupied by a second Wi-Fi device (e.g., the other of MLD 102 and 104) (labeled "Others" in the figure). After gaining access to the low-performance link, the first Wi-Fi device (e.g., MLD 102 / 104) can enable EMLXR mode on the low-performance link L_LO to perform frame switching procedures using multiple spatial streams (e.g., 2ss). In this example, the duration information associated with the frame switching procedure on the high-performance channel L_HI (e.g., the L_LENGTH or PPDU duration of frames transmitted to the Wi-Fi device within duration P72) is obtained after the frame switching procedure on the low-performance link L_LO has started.

[0069] Specifically, the duration information associated with frame exchange sequence 708 is obtained during the time period P73 during which frame exchange sequence 702 occurs on the low-performance link L_LO. Therefore, the duration information associated with the frame exchange procedure on the high-performance link L_HI is stored and then referenced to determine the end time of the frame exchange procedure on the low-performance link L_LO. Figure 7 As shown, multiple frame switching sequences 704 and 706 following frame switching sequence 702 are initiated by a Wi-Fi device (e.g., MLD 102 / 104) within a duration (e.g., TXOP duration) P71, wherein the end time of duration P71 (i.e., the end time of the frame switching procedure on the low-performance link L_LO) coincides with the end time of the frame switching procedure on the high-performance link L_HI. It should be noted that the actual number of frame switching sequences involved in txOnRx alignment may vary depending on the scenario.

[0070] Figure 8 This is a schematic diagram of another multi-link coherent operation with multiple txOnRx alignments according to an embodiment of the present invention. Figure 7 and Figure 8 The main difference between the embodiments shown is that the frame switching sequence 802 (which is the last frame switching sequence) may include padding bits (dummy bits) added to the extended duration P8 to achieve the same purpose of aligning the end time of duration P71 (i.e., the end time of the frame switching procedure on the low-performance link L_LO) with the end time of the frame switching procedure on the high-performance link L_HI.

[0071] about Figure 7 and Figure 8 In the illustrated embodiment, since the end time of the frame switching procedure on the low-performance link L_LO occupied by one Wi-Fi device (e.g., one of MLD 102 and 104) coincides with the end time of the frame switching procedure on the high-performance link L_HI occupied by another Wi-Fi device (e.g., the other of MLD 102 and 104), the Wi-Fi device (e.g., MLD 102 / 104) has an improved opportunity to perform EMLXR operation on the high-performance link L_HI after the high-performance link L_HI becomes idle.

[0072] As an example and not a limitation, the processing circuits 112 / 122 are arranged to handle multiple txOnRx alignments. For example, assume there are 4 asymmetric links L1-L Y(Y=4), control registers 118 / 128 may include a 4-bit control register CR_MTXONRX_COHERENT_EMLXR[0:3], a 16-bit control register CR_EXTEND_DURATION_TXONRX_COHERENT_EMLXR[0:15], and a 4-bit control register CR_EXTEND_TXONRX_COHERENT_EMLXR[0:3]. The 4-bit control register CR_MTXONRX_COHERENT_EMLXR[0:3] records one bit for each link, where a value of "0" indicates that there are no multiple txOnRX alignments for the link, and a value of "1" indicates that there are multiple txOnRX alignments for the link. The 16-bit control register CR_EXTEND_DURATION_TXONRX_COHERENT_EMLXR[0:15] and the 4-bit control register CR_EXTEND_TXONRX_COHERENT_EMLXR[0:3] are used for fill control. The 16-bit control register CR_EXTEND_DURATION_TXONRX_COHERENT_EMLXR[0:15] specifies the maximum padding duration. The 4-bit control register CR_EXTEND_TXONRX_COHERENT_EMLXR[0:3] records one bit for each link, where a value of "0" indicates no txOnRx extension (padding) and a value of "1" indicates txOnRx extension (padding), where the extension duration P8 is shorter than the maximum padding duration specified by the control register CR_EXTEND_DURATION_TXONRX_COHERENT_EMLXR[0:15].

[0073] The use of ordinal terms such as “first,” “second,” and “third” in the claims to modify claim elements does not in itself indicate any priority, precedence, or order of one claim element relative to another claim element, or the chronological order of the execution of method actions. Rather, it is merely used as a marker to distinguish one claim element with the same name from another element with the same name.

[0074] While the embodiments and advantages of the present invention have been described in detail, it should be understood that various changes, substitutions, and modifications can be made to the present invention without departing from the spirit and scope defined by the claims. For example, new embodiments can be derived by combining several parts of different embodiments. The described embodiments are for illustrative purposes only and are not intended to limit the invention. The scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the present invention.

Claims

1. A control method employed by a Wi-Fi multi-link device (MLD), characterized in that, include: In response to obtaining access to the first link at a first time point through channel contention, a multi-link coherent operation mode is enabled on the first link to perform frame switching procedures using N spatial streams on the first link, where N is a positive integer not less than 2; and, In response to obtaining access to the second link at a second time point through channel contention, the multi-link coherent operation mode is not allowed to be enabled on the second link, wherein the performance of the second link is lower than that of the first link.

2. The control method as described in claim 1, characterized in that, The control method also includes: In response to obtaining access to the second link at the second time point through channel contention, a frame switching procedure is performed on the second link using M spatial streams during the first duration, where M is a positive integer less than N.

3. The control method as described in claim 2, characterized in that, M equals 1.

4. The control method as described in claim 2, characterized in that, The control method also includes: In response to gaining access to the first link at a third time point through channel contention, a frame switching procedure is performed on the first link using L spatial streams during a second duration, where L is a positive integer less than N, and the second duration overlaps with the first duration.

5. The control method as described in claim 4, characterized in that, Each of M and L equals 1.

6. The control method as described in claim 4, characterized in that, The control method also includes: Align the end time of the first duration with the end time of the second duration.

7. The control method as described in claim 1, characterized in that, This multi-link coherent operation mode is an enhanced multi-link single-radio EMLSR operation mode.

8. The control method as described in claim 1, characterized in that, This multi-link coherent operation mode is an enhanced multi-link multi-radio EMLMR operation mode.

9. A control method employed by a Wireless Fidelity Wi-Fi Multi-Link Device (MLD), characterized in that, include: In response to obtaining access to a first link through channel contention, a multi-link coherent operation mode is enabled on the first link to perform a frame switching procedure using N spatial streams on the first link, and the end time of the frame switching procedure on the first link is aligned with the end time of another frame switching procedure performed on a second link occupied by another Wi-Fi device, wherein the performance of the second link is higher than that of the first link, and N is a positive integer not less than 2.

10. The control method as described in claim 9, characterized in that, The control method also includes: Before initiating the frame switching procedure on the first link, obtain the duration information associated with the other frame switching procedure on the second link; Aligning the end time of the frame switching procedure on the first link with the end time of the frame switching procedure on the other link includes: The end time of the frame switching procedure on the first link is determined based on this duration information.

11. The control method as described in claim 9, characterized in that, The control method also includes: After the frame switching procedure is started on the first link, the duration information associated with the other frame switching procedure on the second link is acquired and stored; Aligning the end time of the frame switching procedure on the first link with the end time of the frame switching procedure on the other link includes: The end time of the frame switching procedure on the first link is determined based on this duration information.

12. The control method as described in claim 11, characterized in that, The frame switching procedure on the first link includes one or more frame switching sequences initiated after the duration information is obtained.

13. The control method as described in claim 12, characterized in that, The last frame exchange sequence included in the frame exchange procedure on the first link contains padding bits.

14. The control method as described in claim 9, characterized in that, This multi-link coherent operation mode is an enhanced multi-link single-radio EMLSR operation mode.

15. The control method as described in claim 9, characterized in that, This multi-link coherent operation mode is an enhanced multi-link multi-radio EMLMR operation mode.

16. A control method employed by a Wi-Fi multi-link device (MLD), characterized in that, include: Before the first back-back counter of the first link reaches zero and the second link is not occupied, the first back-back counter is held for one or more time slots to wait for the opportunity to access the second link through channel contention, wherein the performance of the second link is higher than that of the first link; In response to the second back-off counter of the second link reaching zero during the period during which the first back-off counter is held, a multi-link coherent operation mode is enabled on the second link to perform a frame switching procedure using N spatial streams, where N is a positive integer not less than 2.

17. The control method as described in claim 16, characterized in that, This multi-link coherent operation mode is an enhanced multi-link single-radio EMLSR operation mode.

18. The control method as described in claim 16, characterized in that, This multi-link coherent operation mode is an enhanced multi-link multi-radio EMLMR operation mode.

19. The control method as described in claim 16, characterized in that, The control method also includes: In response to the second link being occupied by another Wi-Fi device during the period in which the first backoff counter is held, the backoff countdown of the first backoff counter is resumed.

20. The control method as described in claim 19, characterized in that, The rollback countdown to resume the first rollback counter includes: Before resuming the rollback countdown of the first rollback counter, the first rollback counter is kept in place for an additional random time slot.

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