Method for sending data on wireless network and multi-link equipment

Abstract

In accordance with an embodiment of the present invention, a computer-implemented process for automatically synchronizing TXOP of a multi-link device (MLD for short) to improve wireless network performance and avoid IDC interference is described. The process may be performed by a multi-link device that performs a multi-link operation, and the multi-link device may act as a wireless access point or a wireless station. The MLD includes a first wireless station (STA) associated with a first wireless link and a second wireless STA associated with a second wireless link. The MLD may include more wireless STAs for communication over different wireless links.

Description

[0001] Related references

[0002] This application claims priority to U.S. Provisional Application No. 63 / 005,493, filed on April 6, 2020, with Attorney Docket No. MUSI-20-0072PUS; U.S. Provisional Application No. 63 / 033,241, filed on June 2, 2020, with Attorney Docket No. MUSI-20-0108PUS; U.S. Provisional Application No. 63 / 051,416, filed on July 14, 2020, with Attorney Docket No. MUSI-20-0130PUS; and U.S. Non-Provisional Application No. 17 / 219,646, filed on March 31, 2021. The entire contents of the above U.S. Provisional Applications are incorporated herein by reference. Technical Field

[0003] Embodiments of the present invention generally relate to the field of wireless communications. More specifically, embodiments of the present invention relate to systems and methods for transmitting data from a multi-link device. Background Art

[0004] Modern electronic devices often use Wi-Fi to wirelessly send and receive data with other electronic devices, and many of these devices are "dual-band" devices, which include at least two wireless transceivers capable of operating in different frequency bands (e.g., 2.4 GHz, 5 GHz, and 6 GHz). In most cases, wireless devices can only communicate on a single frequency band at a time. For example, older and lower-power devices, such as battery-powered devices, typically operate on the 2.4 GHz band. Newer devices and those that require greater bandwidth typically operate on the 5 GHz band. The availability of the 6 GHz band is a recent development that offers higher performance, lower latency, and faster data rates.

[0005] In some cases, the use of a single frequency band may not meet the bandwidth requirements of a particular device. Therefore, some developing methods for wireless communications increase the communication bandwidth by operating on multiple frequency bands simultaneously (technically referred to as link aggregation or multi-link operation). Multi-link operation can provide higher network throughput and greater network flexibility compared to traditional wireless communication technologies.

[0006] When a multi-link device (MLD) operating on multiple links has data ready for transmission (queued), the MLD must use existing techniques (e.g., asynchronous TXOP) to determine on which link to transmit the queued frames. Each STA in the multi-link device uses its own independent enhanced distributed channel access (EDCA) (e.g., CWmin, CWmax, AIFS, CW, and retry counters) on each link to perform the EDCA mechanism. When the backoff procedure of each STA is called, the backoff counter of each STA is set to a randomly selected integer value. After obtaining a transmission opportunity (TXOP), the STA can initiate the transmission of a frame exchange sequence on the corresponding link. However, when the STAs of the multi-link device send and receive physical layer protocol data units (PPDUs) on multiple links at the same time, in-device coexistence (IDC) interference between wireless links may cause reception errors and degrade the performance of the MLD. The IDC interference caused by using the 5 GHz and 6 GHz bands to transmit and receive simultaneously can be particularly large, depending on the frequency spacing of the operating channels. As a result, some MLDs cannot transmit and receive simultaneously due to IDC interference.

[0007] Therefore, a technique for synchronizing the transmission opportunities of MLDs is sought to improve the performance and reliability of wireless transmissions while avoiding IDC interference caused by simultaneous transmission and reception of MLDs. Summary of the invention

[0008] Therefore, according to an embodiment of the present invention, a computer-implemented process for automatically synchronizing the TXOP of a multi-link device (MLD) to improve wireless network performance and avoid IDC interference is described. The process can be performed by a multi-link device that performs multi-link operations, and the multi-link device can act as a wireless access point or a wireless station. The MLD includes a first wireless station (STA) associated with a first wireless link and a second wireless STA associated with a second wireless link. The MLD may include more wireless STAs for communicating on different wireless links.

[0009] According to one embodiment, a method for transmitting data on a wireless network by a multi-link device (MLD) is disclosed. The method includes performing independent EDCA channel access at a multi-link device on a first wireless link and a second wireless link. The multi-link device includes a first wireless station (STA) associated with the first wireless link and a second wireless STA associated with the second wireless link. The method also includes setting a backoff counter for the first wireless STA and a backoff counter for the second wireless STA according to the independent EDCA channel access, synchronously obtaining a TXOP on the first wireless link and the second wireless link in response to the expiration of the backoff counter, and performing a multi-link operation on the MLD using the first wireless link and the second wireless link during the TXOP.

[0010] According to some embodiments, the method includes receiving timing accuracy information from a second MLD, the timing accuracy information indicating that the second MLD can respond within a time period equal to aSIFSTime+aSignalExtension±TimingErrorMargin measured from an end of transmission of a request frame, wherein the MLD performs multi-link operations in coordination with the second MLD.

[0011] According to some embodiments, the multi-link operation includes sending a first multi-user request to send (MU-RTS) frame using a first wireless STA on a first wireless link, and sending a second MU-RTS frame using a second wireless STA on a second wireless link.

[0012] According to some embodiments, the first MU-RTS frame includes padding that aligns an end time of the first MU-RTS frame with an end time of the second MU-RTS frame.

[0013] According to some embodiments, a first MU-RTS frame includes padding to align reception of a first Clear to Send (CTS) frame with reception of a second CTS frame, wherein the first CTS frame and the second CTS frame are sent in response to the first MU-RTS frame and the second MU-RTS frame, respectively.

[0014] According to some embodiments, the padding field aligns a TXOP of the first radio link with a TXOP of the second radio link.

[0015] According to some embodiments, the method includes configuring a time slot alignment of a first wireless STA to match a time slot alignment of a second wireless STA.

[0016] According to some embodiments, the method includes determining that a backoff counter for a first radio link has expired, delaying a frame exchange sequence on the first radio link until a backoff counter for a second radio link has expired, determining that the backoff counter for the second radio link has expired, and in response to the determination that the backoff counter for the second radio link has expired, initiating a frame exchange sequence on the first radio link during a TXOP, and initiating a frame exchange sequence on the second radio link during the TXOP.

[0017] According to some embodiments, the method includes performing carrier sensing before the first wireless STA initiates a frame exchange sequence.

[0018] According to some embodiments, the back-off counter of the first radio link and the back-off counter of the second radio link are set using a common integer value.

[0019] According to another embodiment, an apparatus for transmitting data on a wireless network is disclosed. The apparatus includes a first wireless station (STA) associated with a first wireless link of the wireless network, a second wireless STA associated with a second wireless link of the wireless network, a memory for storing data, and a processor operable to perform the following operations: performing independent EDCA channel access on the first wireless link and the second wireless link, wherein the multi-link device includes: according to the independent EDCA channel access, setting a backoff counter for the first wireless STA, setting a backoff counter for the second wireless STA, responding that the backoff counter has expired, synchronously acquiring a TXOP on the first wireless link and the second wireless link, and performing a multi-link operation using the first wireless STA on the first wireless STA and the second wireless STA on the second wireless STA during the TXOP.

[0020] According to some embodiments, the method includes receiving timing accuracy information from a second MLD, the timing accuracy information indicating that the second MLD can respond within a time period equal to aSIFSTime+aSignalExtension±TimingErrorMargin measured from an end of transmission of a request frame, wherein the MLD performs multi-link operations in coordination with the second MLD.

[0021] According to some embodiments, the multi-link operation includes sending a first MU-RTS frame on a first wireless link and sending a second MU-RTS frame on a second wireless link.

[0022] According to some embodiments, the first MU-RTS frame includes padding that aligns an end time of the first MU-RTS frame with an end time of the second MU-RTS frame.

[0023] According to some embodiments, the first MU-RTS frame includes a padding field that is set according to an expected channel access delay of the second wireless STA.

[0024] According to some embodiments, the method includes determining that a backoff counter for a first radio link has expired, delaying a frame exchange sequence on the first radio link until a backoff counter for a second radio link has expired, determining that the backoff counter for the second radio link has expired, and in response to the determination that the backoff counter for the second radio link has expired, initiating a frame exchange sequence on the first radio link during a TXOP and initiating a frame exchange sequence on the second radio link during the TXOP.

[0025] According to some embodiments, the back-off counter of the first radio link and the back-off counter of the second radio link are set using a common integer value. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention:

[0027] Figure 1 An exemplary wireless communication system including a multi-link cooperative AP and a multi-link cooperative STA according to an embodiment of the present invention is described.

[0028] Figure 2 Depicted is a block diagram of an exemplary MLD (eg, a wireless AP capable of operating on multiple links) including more than one affiliated STA and including a MAC SAP to an LLC.

[0029] Figure 3 FIG. 4 is a block diagram of an exemplary MAC layer protocol of an MLD according to an embodiment of the present invention, wherein the MLD includes a high-level MAC layer protocol and a low-level MAC layer protocol.

[0030] Figure 4 A block diagram depicts an exemplary STA frame queue in which frames are queued for transmission at a lower MAC layer protocol according to an access category associated with the frame.

[0031] Figure 5 is an exemplary transmission timing diagram of an exemplary MLD (eg, a multi-link AP or a multi-link STA) that does not use synchronized TXOP according to an embodiment of the present invention.

[0032] Figure 6 is an exemplary transmission timing diagram of an exemplary MLD (eg, a multi-link AP or a multi-link STA) for synchronizing TXOPs to perform synchronous multi-link transmission according to an embodiment of the present invention.

[0033] Figure 7is an exemplary transmission timing diagram of an exemplary MLD (eg, a multi-link AP or a multi-link STA) including an occupied link according to an embodiment of the present invention.

[0034] Figure 8 is an exemplary transmission timing diagram of an MLD for transmitting a MU-RTS frame including a padding field for aligning CTS frame reception in a wireless network according to an embodiment of the present invention.

[0035] Fig. 9 is an exemplary MLD transmission timing diagram for synchronous TXOP according to an embodiment of the present invention, in which STAs delay transmission using a backoff counter set according to a common integer value.

[0036] Fig.10 is an exemplary MLD transmission timing diagram for synchronous TXOP according to an embodiment of the present invention, in which a STA delays transmission until another STA of the MLD is ready to transmit.

[0037] Fig.11 is an exemplary MLD transmission timing diagram according to an embodiment of the present invention, which depicts a synchronous TXOP procedure for setting a backoff counter after delaying transmission until another STA of the MLD is ready to transmit.

[0038] Fig.12 is an exemplary MLD transmission timing diagram according to an embodiment of the present invention, which depicts the backoff procedure of the corresponding wireless links of the STAs of the MLD recovered using the same slot boundary alignment to solve the slot boundary problem.

[0039] Fig.13 is an exemplary MLD transmission timing diagram according to an embodiment of the present invention, which depicts time slot boundaries of multiple wireless links of an unsynchronized MLD, where a STA of the MLD has a backoff counter that has reached 0, which delays the initiation of a frame exchange sequence until another STA of the MLD also obtains a TXOP.

[0040] Fig.14 is an exemplary MLD transmission timing diagram according to an embodiment of the present invention, which depicts misaligned slot boundaries, wherein a STA of the MLD delays the initiation of its frame exchange sequence to align its slot boundary with other STAs.

[0041] Fig.15 is a flow chart of an exemplary computer-implemented process for automatically synchronizing TXOPs of MLDs to improve wireless network performance and avoid IDC interference according to an embodiment of the present invention.

[0042] Fig.16 A block diagram depicts an exemplary computer system platform upon which embodiments of the invention may be implemented. DETAILED DESCRIPTION

[0043] Several embodiments will be referenced in detail. Although the subject matter will be described in conjunction with alternative embodiments, it should be understood that they are not intended to limit the claimed subject matter to those embodiments. On the contrary, the claimed subject matter is intended to cover alternatives, modifications, and equivalents, which may be included within the spirit and scope of the claimed subject matter as defined by the appended claims.

[0044] Furthermore, in the following detailed description, numerous specific details are described in order to provide a thorough understanding of the claimed subject matter. However, those skilled in the art will recognize that the embodiments can be practiced without these specific details or their equivalents. In other cases, well-known methods, processes, components, and circuits have not been described in detail to avoid unnecessarily obscuring aspects and features of the subject matter.

[0045] Portions of the following detailed description are presented and discussed in terms of methods. Although in the diagrams (e.g., Fig.15 ) discloses its steps and sequence, but these steps and sequence are exemplary. The embodiments are very suitable for executing various other steps or variations of the steps listed in the flowcharts of the drawings of this document, and can be executed in a sequence different from that depicted and described in this document.

[0046] Certain parts of the detailed description may be presented in terms of processes, steps, logic blocks, processing and other symbolic representations of operations on data bits that can be performed on computer memory. These descriptions and representations are means used by those of ordinary skill in the field of data processing to most effectively convey the essence of their work to other persons of ordinary skill in the art. Here, programs, computer-executed steps, logic blocks, processes, etc. are generally considered to be self-consistent sequences of steps or instructions that lead to desired results. These steps are steps that require physical manipulation of physical quantities. Typically, although not necessarily, these quantities take the form of electrical or magnetic signals that can be stored, transmitted, combined, compared and otherwise manipulated in a computer system. It has been proven that it is sometimes convenient to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, etc., mainly for general reasons.

[0047] It should be borne in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless expressly stated otherwise, as will be apparent from the following discussion, it should be understood that throughout the discussion, terms such as "access," "configure," "coordinate," "store," "transmit," "authenticate," "identify," "request," "report," "determine," and the like are used to refer to the operations and processes of a computer system or similar electronic computing device that manipulates and transforms data represented as physical (electronic) quantities in the computer system's registers and memory into other data similarly represented as physical quantities in the computer system's memory or registers or other such information storage, transmission, or display devices.

[0048] Some embodiments are described in the general context of computer-executable instructions (e.g., program modules) executed by one or more computers or other devices. Typically, program modules include routines, programs, objects, components, data structures, etc. that perform specific tasks or implement specific abstract data types. Typically, in various embodiments, the functionality of the program modules can be combined or distributed as desired.

[0049] Synchronous Multilink Wireless TXOP Procedure

[0050] As used herein, the term "EHT" generally refers to a new generation of wireless communications (e.g., Wi-Fi) known as Extremely High Throughput (EHT), and is defined in accordance with the IEEE 802.11be standard. The term station (STA) generally refers to an electronic device capable of sending and receiving data via Wi-Fi. Some wireless STAs are configured to act as wireless access points (APs).

[0051] Compared with traditional techniques for wireless communication, multi-link operation can provide higher network throughput and improved network flexibility. Embodiments of the present invention provide techniques for simultaneously sending frames on multiple links in multi-link operation between wireless devices using synchronized transmission opportunities (TXOPs). According to some embodiments, the time slot boundaries of multiple links are aligned so that TXOPs can be obtained on multiple links.

[0052] about Figure 1, according to an embodiment of the present invention, an exemplary wireless communication system 100 including a multi-link cooperative AP 105 and a multi-link cooperative STA 155 is depicted. The multi-link cooperative AP 105 includes a 5 GHz transceiver 110 and a 2.4 GHz transceiver 115. According to an embodiment of the present invention, other types of transceivers operating on different frequency bands such as 6 GHz and above may also be used by the multi-link cooperative AP 105. The transceivers 110 and 115 of the AP 105 exchange data and information with a cooperation management unit 120, which coordinates the information sent and / or received by the transceivers 110 and 115. Each transceiver of the multi-link cooperative AP 105 can be regarded as a separate wireless station attached to the multi-link cooperative AP 105.

[0053] The multi-link cooperative ST 155 includes a 5 GHz transceiver 160 and a 2.4 GHz transceiver 165. According to some embodiments of the present invention, other types of transceivers 155 operating on different frequency bands (e.g., 6 GHz and above) may also be used by the multi-link cooperative STA. Although any well-known wireless communication band (e.g., 6 GHz) is used, the transceivers 160 and 165 of the STA55 exchange data and information with the cooperation management unit 170, which coordinates the information sent and received by the transceivers 160 and 165 using the 5 GHz band wireless communication and the 2.4 GHz band wireless communication, respectively. Each transceiver of the multi-link cooperative STA 155 can be considered as a separate wireless station attached to the multi-link cooperative STA155.

[0054] The STA 155 sending frames using multiple frequency bands simultaneously can reduce latency and improve the peak throughput of the STA 155. However, in some cases, sending frames using multiple frequency bands simultaneously can degrade the performance of the basic service set (BSS) including the STA 155. For example, when STAs 155 operating on multiple frequency bands simultaneously use a large amount of bandwidth available to the BSS due to increased traffic, the performance of the BSS may be degraded. Therefore, the AP 105 can control which STAs are granted multi-link channel access, and access can be terminated by the AP at any time based on, for example, changing network conditions or requirements.

[0055] Depending on certain conditions such as traffic load, a non-AP STA may use fewer than all supported / available links to reduce energy consumption. In addition, the non-AP STA may apply separate power management to each link, and the AP may provide TID-to-link mapping information for each link. According to the Quality of Service (QoS) policy of the Basic Service Set (BSS), the AP may allocate traffic to different links according to traffic type (e.g., voice, video, data, etc.). For example, frames belonging to a first traffic identifier (Traffic Identifier, TID 1) are allocated to a first link, and frames belonging to a second traffic identifier (TID 2) are allocated to a second link. In this case, the AP may provide TID-to-link mapping information for the two links to the wireless STA, where some data can only be sent on the first link and other data can only be sent on the second link.

[0056] Data transmitted on a first wireless link (e.g., a 5 GHz wireless link provided by 5 GHz transceiver 110 or 160) may be retransmitted on a different wireless link. For example, if a data transmission on a 5 GHz wireless link is not successfully sent (e.g., an acknowledgment is not received), the data may be retransmitted on a 2.4 GHz wireless link provided by 2.4 GHz transceiver 115 / 165. According to embodiments of the present invention described herein, a data transmission (e.g., a PPDU) is initially encoded for transmission on a first wireless link (e.g., a 2.4 GHz or 5 GHz wireless link), and retransmission data is prepared for transmission to encrypt the data for retransmission in a multi-link environment.

[0057] Figure 2 is a block diagram depicting an exemplary MLD 200 (e.g., a wireless AP capable of operating on multiple links) according to an embodiment of the present invention, the exemplary MLD 200 including more than one affiliated STA. The MLD entity 205 uses the STA instance 210 and / or the STA instance 215 to access the wireless medium (wireless medium, referred to as WM). The MLD entity 220 includes a STA instance 225 for accessing the wireless medium. The MAC SAP receives data from the distribution system (DS) for transmission over the wireless medium. The STA instances 210, 215, 225 can be used to perform multi-link operations, such as synchronous multi-link transmissions. It should be understood that the STAs affiliated with the MLD can be operated independently and follow the baseline Enhanced Distributed Channel Access (EDCA) mechanism for accessing channels.

[0058] The wireless STA 200 can perform common management signaling across the MLD entity 205 and the MLD entity 220. During multi-link operation, the wireless STA 200 can be regarded as a single device. STA 205, 210 and 225 use the WM media access control (media access control, referred to as MAC) address to identify themselves to peer devices. The wireless STA 200 includes a MAC service access point (service access point, referred to as SAP) interface 230 (MAC Addr M1) and 235 (MAC Addr M2), which can receive a plaintext MPDU for wireless transmission through the WM using different links. For example, a different MAC layer address is associated with each wireless link accessed by the wireless STA 200. The address of the MAC SAP 230 of the MLD entity 205 and the address of the MAC SAP 235 of the MLD 220 can be used for key generation, SA setting and encryption of retransmitted data, thereby retransmitting the encrypted MPDU on the wireless link.

[0059] According to an embodiment of the present invention, Figure 3 , an exemplary MAC layer protocol 300 of the MLD includes a high-level MAC layer protocol 305 and low-level MAC layer protocols 310 and 315. Synchronous TXOPs transmitted from the MLD can be implemented without changing the low-level MAC layer protocol 305, and without changing existing backoff procedures (e.g., baseline EDCA procedures). In order to implement a synchronous TXOP for the MLD, MPDUs from the MLD queue 320 are moved to a selected STA queue based on a random back-off (RBO) counter of an attached STA. Before a transmitter of a STA of the MLD is selected for transmission, the MLD uses the MLD queue 320 of the high-level MAC layer protocol 305 to buffer frames (e.g., MPDUs). After a transmitter of a STA attached to the MLD is selected, the MLD buffers the MPDUs in the STA queue associated with the transmitter (e.g., STA queue 325 or STA queue 330). As described below with respect to Figure 4 Discussing in more detail, the STA queues 325 and 330 may include transmit queues for queuing frames of different access categories (ACs).

[0060] The MLD includes a multi-link management / scheduler 370 for scheduling frame transmissions during a TXOP. Figure 3As shown, the multi-link management / scheduler 370 of the high MAC layer protocol 305 receives the RBO counter from the Enhanced Distributed Channel Access Function (EDCAF) 335 and 340 of the low MAC layer protocols 310 and 315, respectively, and schedules frames for transmission using the STA queue 325 and the STA queue 330. According to the scheduling of the multi-link management / scheduler 370, the frame is queued in the STA queue 325 or the STA queue 330 for transmission, and is passed to the PHY layer protocol 345 or the PHY layer protocol 350, respectively, for transmission through the wireless medium.

[0061] like Figure 4 As shown in the exemplary STA queue 400 of FIG. 4 , frames (e.g., MAC Service Data Units (MSDUs)) are queued for transmission at lower MAC layer protocols according to access categories (ACs) associated with the frames. ACs include voice data (VO), video data (VI), best effort data (BE), and background data (BK). Each AC includes a dedicated transmit queue and an EDCAF capable of internal conflict resolution. Frames ready for transmission are queued according to their ACs and transmitted by synchronizing TXOPs between multiple available interfaces for transmission on multiple wireless links.

[0062] Figure 5 An exemplary transmission timing diagram 500 is depicted for an exemplary MLD 515 (eg, a multi-link AP or a multi-link STA) that does not use synchronous TXOP according to an embodiment of the present invention. Figure 5 In the example of , MLD 515 checks the RBO counter of each STA (e.g., STA1 and STA2) associated with the MLD. If the RBO counter of the STA is equal to 0, MLD 515 can pass the MPDU from the MLD queue to the STA queue corresponding to the available wireless link. Once queued, the STA can initiate a TXOP for the frame exchange sequence. Figure 5In the example of , STA1's backoff counter reaches 0, and an MPDU (e.g., A-MPDU 505) is passed from the MLD queue to the STA1 queue. In response to the transmission, STA1 initiates a TXOP for a frame exchange sequence to transmit the A-MPDU 505 and receive a block acknowledgment (BA) 510. Due to potential IDC interference caused by ongoing STA1 transmission and / or reception, the wireless links of other STAs (e.g., STA2) of the MLD 515 are considered busy. Figure 5 In the example of FIG. 1 , STA1 and STA2 do not use synchronous multi-link transmission to send data. According to an embodiment of the present invention, synchronous multi-link transmission is enabled to improve wireless network performance.

[0063] Figure 6 An exemplary transmission timing diagram 600 depicts an exemplary MLD 625 (eg, a multi-link AP or a multi-link STA) for synchronizing TXOPs to perform synchronous multi-link transmissions according to an embodiment of the present invention. Figure 5 The frame exchange sequence shown is reversed, during a synchronous TXOP Figure 6 The frame exchange sequence shown is performed simultaneously on multiple links to improve the throughput of wireless transmission. When the RBO counter of a STA (e.g., STA1) attached to the MLD reaches 0, when the RBO counter of another attached STA (e.g., STA2) has almost reached 0, the MLD 625 may decide not to pass the queued MPDU from its MLD queue to the STA1 queue. In this case, STA1 has not yet initiated a TXOP, and STA2 continues its backoff procedure. When the RBO counter of STA2 is equal to 0, the MLD passes the MPDU from the MLD queue to the STA2 queue and the STA1 queue. At this time, STA1 and STA2 can initiate a TXOP at the same time. It should be understood that if the medium is not busy according to the baseline rule, the STA (e.g., STA1) does not call a new backoff procedure. In other words, if the transmission queue becomes non-idle and the medium is in an idle state, the backoff procedure is not used. Figure 6 In the example of FIG. 1 , after both backoff counters reach 0, STA1 and STA2 simultaneously transmit frames A-MPDU 605 and 610 during a synchronized TXOP. BA 615 and 620 are received from the receivers of A-MPDU 605 and 610 during the TXOP. In this way, simultaneous transmission and reception of MLDs are avoided, and transmitting data on multiple wireless links simultaneously substantially improves the performance and reliability of MLD 625.

[0064] Figure 7An exemplary transmission timing diagram 700 of an exemplary MLD 715 (eg, a multi-link AP or a multi-link STA) including transmission links occupied during a TXOP is depicted in accordance with an embodiment of the present invention. Figure 7 In the example of , STA1's wireless medium is busy (determined by physical carrier sense (CS), virtual CS, or TXNAV counter value). In this case, only STA2 initiates TXOP to send A-MPDU 705 and receive BA 710. When the medium (STA1's wireless link) becomes idle (e.g., according to the baseline backoff procedure), STA1 invokes a new backoff procedure. Optionally, when STA1's wireless medium becomes available, STA1 can remove the MPDU from the STA1 queue to retry synchronous multi-link transmission with STA2.

[0065] According to some embodiments, when a MA-UNITDATA.request primitive (generated by an LLC sublayer entity) queues a frame associated with the AC (or priority) for transmission, the EDCAF invokes a backoff procedure such that one of the transmit queues associated with the AC becomes non-idle and any other transmit queues associated with the AC are empty. The wireless medium is determined to be busy on the primary channel based on a physical CS, a virtual CS, or a non-zero TXNAV counter value. If the request is satisfied based on the parameters of the request, the MAC sublayer entity formats the frame appropriately and then passes it to lower layers for transmission to one or more peer MAC sublayer entities.

[0066] Timing requirements for multi-link transmission

[0067] When a wireless STA transmits frames on multiple links with different TXVECTOR parameters (such as PPDU format, GI or LTF type), it may be difficult to accurately synchronize the start time and end time of the transmission. According to some embodiments, the start time and end time of the transmission on multiple links are synchronized within a time period equal to aSIFSTime+aSignalExtension. To meet this requirement, for example, the STA may apply MAC padding, PHY padding, or packet extension (PE for short). When operating in the 2.4 GHz band, aSignalExtension is equal to 6μs, and when operating in the 5 GHz or 6 GHz band, aSignalExtension is equal to 0μs. When operating in the 2.4 GHz band, aSIFSTime is equal to 10μs, and when operating in the 5 GHz or 6 GHz band, aSIFSTime is equal to 16μs. Therefore, for both the 2.4 GHz band and the 5 / 6 GHz band, the value of aSIFSTime+aSignalExtension is equal to 16μs.

[0068] When the same interframe spacing (e.g., SIFS, PIFS, or AIFS) is used on multiple links, if the end times of transmissions on multiple links are synchronized within aSIFSTime+aSignalExtension, the start times of subsequent transmissions are also synchronized in aSIFSTime+aSignalExtension. Therefore, the start time of the initial frame does not need to be synchronized. The end times of transmissions on multiple links are synchronized unless the frame is the first (initial) frame of a TXOP. When the timing error caused by OFDM symbol misalignment is limited to less than 16μs, to synchronize the end times of transmissions on multiple links in aSIFSTime+aSignalExtension, only MAC padding (e.g., EOF padding subframe or padding subfield) may be required. In this case, the PHY layer protocol does not need to be changed.

[0069] According to some embodiments, when the SIFS timing accuracy of STAs within a multi-link capable device is different (e.g., different PPDU formats, GIs, LTF types, etc.), transmission and reception are allowed to overlap within the SIFS period. For example, when the SIFS timing accuracy of the STA is ±0.4μs, according to the 11ax requirements of the HE TB PPDU, transmission and reception will overlap.

[0070] To solve or avoid the SIFS timing accuracy problem, the timing accuracy requirements of the STAs attached to the MLD can be adjusted. For example, based on the TimingErrorMargin information received from the peer STA (attached to other devices), the end time of the transmission on the multilink can be synchronized within a time period equal to aSIFSTime+aSignalExtension–TimingErrorMargin. The TimingErrorMargin indicates that the peer STA can respond to the STA within aSIFSTime+aSignalExtension±TimingErrorMargin from the end of the request frame.

[0071] According to an embodiment of the present invention, Figure 8 As shown, in an exemplary MLD transmission timing diagram 800, a Multi-user Request to Send (MU-RTS) frame including a padding field may be used to align the reception of a Clear to Send (CTS) frame in a wireless network. The padding field in the MU-RTS frame is used to delay the associated CTS response until a second MU-RTS frame on another link of the MLD is sent and received by the peer STA. The length of the padding field in the first MU-RTS frame is set to the expected channel access delay until another STA (of the same multi-link device) obtains a TXOP on its link. For example, the expected channel access delay is set to a minimum value greater than or equal to AIFS[AC]+backoff counter (for the AC)*aSlotTime (for a group of ACs). The expected channel access delay may also be set to be less than a predetermined threshold (locally configured). If an expected channel access delay value that satisfies the above conditions does not exist, the MU-RTS frame is sent without a padding field.

[0072] exist Figure 8In the example of MLD transmission timing diagram 800, the padding field 805 of the MU-RTS frame 810 is used to align the transmission of CTS frames 815 and 820. For example, the padding value of the padding field 805 may be set according to the expected channel access time being greater than or equal to AIFS[AC]+the minimum value of the backoff counter (for the AC)*aSlotTime or according to a predetermined value. In this way, IDC interference caused by overlapping transmission and reception of MLD is avoided, thereby improving the performance of the wireless network. In some cases, such as when transmitting a non-HT PPDU that does not support any padding mechanism, the end time of transmission on multiple links may not be synchronized. Therefore, according to some embodiments, when the time slot boundaries used by the STAs of the MLD are not aligned and the padding mechanism is not supported, only a single wireless link is used for the transmission of the MLD to avoid potential IDC interference caused by simultaneous transmission and reception of the MLD.

[0073] New TXOP Synchronization Technology for Multi-link Devices

[0074] Embodiments of the present invention provide a novel TXOP synchronization method for MLD. Fig. 9 According to some embodiments, each STA of a multi-link device (e.g., STA1 and ST2) performs separate EDCA channel access on an associated link using its own EDCA parameters (CWmin, CWmax, AIFS, CW, and retry counter). When each STA's backoff procedure is invoked, the backoff counter of each STA is set to a common integer value in order to simultaneously obtain a TXOP on the link. After simultaneously obtaining a TXOP on the link, the STAs may simultaneously use the link to initiate transmission of a frame exchange sequence. Fig. 9 In the MLD transmission timing diagram 900, AP1 transmits a data frame 905 (Seq3) synchronously with AP2 transmits a data frame 910 (Seq1), and AP1 transmits a data frame 915 (Seq4) synchronously with AP2 transmits a data frame 920 (Seq2). AP1 and AP2 simultaneously receive BAs 925 and 930 that confirm the transmitted data frames. In this way, the simultaneous transmission and reception of data by AP1 and AP2 of the MLD is advantageously avoided, thereby avoiding IDC interference.

[0075] exist Fig. 9 In the example of , a common integer value of the backoff counter of each STA is determined. Specifically, when the contention window of the access category (CW[AC]) of each STA is the same, the multi-link device randomly selects a uniformly distributed integer value having a value ranging from 0 to CW[AC] as the common integer value. Fig. 9 In the example above, the public integer value is 5.

[0076] Two configurations for use when the CW[AC] of each STA is different are described. In the first configuration, each STA in the multi-link device randomly selects an integer value from a uniform distribution of values ​​ranging from 0 to the CW[AC] of each STA. The multi-link device selects the maximum of the selected integer values ​​as the common integer value. In the second configuration, the multi-link device randomly selects an integer value from a uniform distribution of values ​​ranging from 0 to the maximum CW[AC] among all STAs to use as the common integer value.

[0077] Fig.10 An exemplary MLD transmission timing diagram for synchronous TXOP according to an embodiment of the present invention is depicted, in which a STA delays transmission until another STA of the MLD is ready to transmit. Fig.10 As shown, after obtaining TXOP on one link, if another STA in the same multi-link device still has a non-zero backoff counter, the STA with the backoff counter that has reached 0 delays initiating the frame exchange sequence until the other STA also obtains TXOP. In this case, the STA that has delayed initiating the frame exchange sequence performs physical and virtual CS during a predetermined interval (e.g., PIFS) before initiating the frame exchange sequence to determine whether the link becomes busy during the delay. In this way, multiple STAs can use TXOP on multiple links at the same time, and IDC interference is avoided.

[0078] exist Fig.10 In the example of , the backoff counter of AP2 reaches 0 before the backoff counter of AP1 reaches 0. Therefore, AP2 delays the initiation of the frame exchange sequence 1005 until AP1 is also ready to send. When the backoff counter of AP1 reaches 0, both AP1 and AP2 will receive a TXOP to synchronously initiate the frame exchange sequence in the MLD without encountering IDC interference (e.g., on the 5 GHz link and the 6 GHz link) because the simultaneous transmission and reception by the MLD are advantageously avoided. Frame exchange sequences 1005 and 1010 are executed simultaneously on the 5 GHz and 6 GHz wireless links, respectively. According to some embodiments, the delay time is limited according to the EDCA channel access rules. In this case, at each specific time slot boundary, the EDCAF may decide not to perform any operation. Therefore, the backoff counter is maintained at a non-zero value (e.g., a value of 1) for a period of time to reduce the delay time after the backoff counter reaches 0, which is limited according to the EDCA channel access rules.

[0079] Fig.11 An MLD transmission timing diagram 1100 is depicted for an exemplary synchronous TXOP procedure according to an embodiment of the present invention for setting a backoff counter after delaying transmission until another STA of the MLD is ready to transmit. Fig.11As shown, when EDCA channel access is restored on a single link after delaying EDCA channel access, the STA invokes a new backoff procedure (e.g., initiation of a backoff procedure and frame exchange sequence). For example, CW[AC] may be reset to CWmin[AC], and the backoff counter may be set to a randomly selected value having a uniform distribution of values ​​ranging from 0 to CW[AC]. Fig.11 In the example of FIG. 1 , AP2 delays the initiation of the frame exchange sequence 1105 so that AP1 is ready for synchronization with MLD. However, the wireless medium of AP1 becomes busy, so AP2 invokes a new backoff procedure and sends the frame exchange sequence 1105 on a single link instead of waiting for the wireless medium of AP1 to be available for MLD. The backoff counter of AP2 is set to a uniformly distributed randomly selected value in the range of values ​​(e.g., 6) from 0 to CW[AC].

[0080] According to some embodiments, delaying EDCA channel access until another STA obtains TXOP is enabled only when there are frames available for transmission at the EDCAF. Otherwise, delaying EDCA channel access is not allowed to avoid multiple MLDs delaying EDCA channel access after the backoff procedure.

[0081] Novel slot boundary alignment for synchronous TXOP

[0082] According to some embodiments, for a specific time slot boundary of the wireless medium, each EDCAF determines to perform one and only one of the following functions according to the rules described below:

[0083] 1. Decrement the backoff counter;

[0084] 2. Initiate the transmission of the frame exchange sequence;

[0085] 3. The backoff procedure is invoked due to an internal conflict; or

[0086] 4. Do nothing.

[0087] At each specific time slot boundary, each EDCAF decrements the backoff counter if its backoff counter has a non-zero value. Each EDCAF initiates a transmission sequence if there are frames available for transmission at the EDCAF, the value of the backoff counter of the EDCAF is 0, and the initiation of transmission sequences is not allowed for EDCAFs with higher user priority. Each EDCAF invokes a backoff procedure and reports internal collisions if there are frames available for transmission at the EDCAF, the value of the backoff counter of the EDCAF is 0, and the initiation of transmission sequences is allowed for EDCAFs with higher user priority. Otherwise, the EDCAF does not perform any operation.

[0088] In some cases, even when a common backoff counter is used, if the slot boundaries of the multiple links are not synchronized, the multi-link device may not be able to synchronize to obtain a TXOP. According to some embodiments of the present invention, the slot boundaries of the multiple links used by the MLD are synchronized to obtain a synchronized TXOP for multi-link operation. For example, this may include delaying the transmission of one wireless STA of the MLD to align with the slot boundary of another wireless STA of the MLD.

[0089] As in Fig.12 As depicted in the exemplary MLD transmission timing diagram 1200 of FIG. 1 , according to an embodiment of the present invention, the backoff procedures of the corresponding wireless links of the MLD STAs are restored using the same slot boundary alignment to resolve the slot boundary issue. For example, the slot boundary of the STA that most recently accessed the medium is applied to the MLD STA that performs multi-link operation. Fig.12 In the example of FIG. 1 , AP1 transmits a data frame 1205 using a first slot alignment, and AP2 transmits a data frame 1210 using a second slot alignment. For subsequent transmissions, the slot boundary based on the STA (STA2) that most recently accessed the medium is applied to the slot boundary of the other link. After an arbitration inter-frame spacing (AIFS) period, AP1 and AP2 perform synchronization backoff procedures for frame exchange sequences 1215 and 1220, respectively, using slot boundary alignment based on the medium access activity from wireless STA2. In this way, the slot alignment problem is solved, and IDC interference is advantageously avoided.

[0090] about Fig.13 According to some embodiments, when the time slot boundaries of multiple wireless links of the MLD are not synchronized, the STA of the MLD with the backoff counter that has reached 0 delays the initiation of the frame exchange sequence until another STA of the MLD also obtains a TXOP. In this case, the STA that delays the initiation of the frame exchange sequence performs physical and virtual CS during aSlotTime before initiating the frame exchange sequence. The upper limit of the delay time can be set to aSlotTime (e.g., 9us). Fig.13 In the example shown in FIG. 13 , AP2 has reached 0 on the backoff counter on the 5 GHz link. AP2 delays the initiation of data transmission 1305 by a maximum time sSlotTime. AP2 performs physical and virtual CS during aSlotTime before initiating the frame exchange sequence 1310. In this way, the time slot boundaries of AP1 and AP2 are aligned, and IDC interference between the 5 GHz and 6 GHz radio links is avoided when performing MLO.

[0091] like Fig.14As shown, according to an embodiment of the present invention, when a STA of the same MLD can access the wireless medium immediately after PIFS or AIFS, but the time slot boundaries of the STAs are not synchronized, the STA of the MLD can delay the initiation of its frame exchange sequence to align its time slot boundary with that of another STA. The STA that delays the initiation of the frame exchange sequence performs physical and virtual CS during aSlotTime before starting the initiation of the frame exchange sequence. Fig.14 In the example of FIG. 1 , both AP1 and AP2 can transmit over the unoccupied 5 GHz and 6 GHz radio links. AP2 delays the initiation of data transmission 1405 on the 5 GHz link (maximum time aSlotTime) to synchronize the slot time alignment of AP2 with the slot time alignment of AP1. While AP1 initiates the frame exchange sequence 1410 in the synchronous TXOP, AP2 performs physical and virtual CS during aSlotTime before AP2 initiates the frame exchange sequence 1405. In this way, the slot boundaries of AP1 and AP2 are aligned, and MLO can be performed on the 5 GHz and 6 GHz radio links, and IDC interference between the 5 GHz and 6 GHz radio links can be avoided.

[0092] Example process of TXOP synchronization in multi-link devices

[0093] about Fig.15 , according to an embodiment of the present invention, an exemplary computer-implemented process 1500 for automatically synchronizing TXOPs of MLDs to improve wireless network performance and avoid IDC interference is shown. Process 1500 can be performed by a multi-link device that performs multi-link operations, and the multi-link device can act as a wireless access point or a wireless station. The MLD includes a first wireless station (STA) associated with a first wireless link and a second wireless STA associated with a second wireless link. The MLD may include more wireless STAs for communicating on different wireless links.

[0094] In step 1505, separate EDCA channel access is performed on the first wireless link and the second wireless link.

[0095] In step 1510, according to the separate EDCA channel access, a backoff counter of the first wireless STA is set, and a backoff counter of the second wireless STA is set.

[0096] In step 1515, in response to the backoff counter having expired, TXOPs are synchronously acquired on the first radio link and on the second radio link.

[0097] In step 1520, during the TXOP, a multi-link operation is performed using the first radio link and the second radio link.

[0098] The multi-link operation performed in step 1520 during the TXOP may include adding padding on the wireless link or otherwise delaying transmission to synchronize the transmission. For example, padding may be added to the MU-RTS frame to align the end time of the frame, and synchronize the reception of the CTS frame sent in response to the MU-RTS frame. In some embodiments, a backoff counter for initiating transmission on the first wireless link and the second wireless link is set according to a common integer value. According to other embodiments, the multi-link operation includes aligning the time slot times of the first wireless STA and the second wireless STA. These steps align (synchronize) the TXOPs of the first wireless STA and the second wireless STA to avoid IDC interference and improve wireless network performance.

[0099] Exemplary Computer Control System

[0100] Fig.16 An exemplary wireless device 1600 is depicted in which embodiments of the present invention may be implemented. Embodiments of the present invention relate to a multi-link device capable of performing multi-link operations. The multi-link device may act as a wireless access point or a wireless station. An exemplary MLD includes a first wireless station (STA) associated with a first wireless link and a second wireless STA associated with a second wireless link. The MLD may include more wireless STAs for communicating on different wireless links to further improve network performance. The multi-link operations performed by the wireless device during a synchronous TXOP may include adding padding or otherwise delaying transmissions on a wireless link to synchronize transmissions on multiple wireless links.

[0101] The wireless device 1600 includes a processor 1605 for running software applications and optionally an operating system. The memory 1610 may include read-only memory and / or random access memory, for example, to store applications and data used by the processor 1605 and data received or sent by the transceivers 1620, 1625, and 1630. According to some embodiments, the wireless device 1600 may include less memory or more transceivers. The transceivers 1620, 1625, 1630 communicate with other electronic devices on a wireless network (e.g., WLAN) and generally operate according to IEEE standards (e.g., IEEE 802.11ax, IEEE 802.11ay, IEEE 802.11be, etc.).

[0102] Thus, embodiments of the present invention are described. Although the present invention has been described in particular embodiments, it should be understood that the present invention should not be construed as limited to such embodiments but should be construed in accordance with the appended claims.

Claims

1. A method for sending data on a wireless network by a multi-link device, comprising: Independent enhanced distributed channel access is performed at a multi-link device on a first wireless link and a second wireless link, wherein the multi-link device comprises: a first wireless station associated with the first wireless link; and a second wireless station associated with the second wireless link; Determining that a backoff counter of the first radio link has reached 0; acquiring a transmission opportunity on the first wireless link; determining that the second wireless station has not acquired a transmission opportunity on the second wireless link; delaying a frame exchange sequence on the first radio link until a backoff counter of the second radio link reaches 0; Determining that the backoff counter on the second wireless link has reached 0; In response to determining that the backoff counter on the second radio link has reached 0, acquiring a transmission opportunity on the second radio link; In response to acquiring the transmission opportunity on the second radio link, when physical carrier sensing and virtual carrier sensing indicate that the first radio link is idle, performing a multilink operation at the multilink device using the first radio link and the second radio link; During the transmission opportunity on the first radio link, initiating the frame exchange sequence on the first radio link; and During the transmission opportunity on the second radio link, a frame exchange sequence is initiated on the second radio link.

2. The method for sending data on a wireless network by a multi-link device as claimed in claim 1, characterized in that: The method further comprises: receiving timing accuracy information from a second multi-link device, the timing accuracy information indicating that the second multi-link device responded within a time period equal to aSIFSTime+aSignalExtension±TimingErrorMargin measured from the end of transmission of the request frame, The multi-link device and the second multi-link device cooperate to perform the multi-link operation.

3. The method for sending data on a wireless network by a multi-link device as claimed in claim 1, characterized in that: The multi-link operation includes: Sending a first multi-user transmission request frame using the first wireless station over the first wireless link; and A second multi-user transmission request frame is sent using the second wireless station over the second wireless link.

4. The method for sending data on a wireless network by a multi-link device as claimed in claim 3, characterized in that: The first multi-user transmission request frame includes padding for aligning an end time of the first multi-user transmission request frame with an end time of the second multi-user transmission request frame.

5. The method for sending data on a wireless network by a multi-link device as claimed in claim 3, characterized in that: The first multi-user transmit request frame includes padding to align reception of a first grant to send frame with reception of a second grant to send frame, wherein the first grant to send frame and the second grant to send frame are respectively transmitted in response to the first multi-user transmit request frame and the second multi-user transmit request frame.

6. The method for sending data on a wireless network by a multi-link device as claimed in claim 5, characterized in that: The padding is located in a padding field, and the padding field aligns a transmission opportunity of the first radio link with a transmission opportunity of the second radio link.

7. The method for sending data on a wireless network by a multi-link device as claimed in claim 1, characterized in that: The method further includes configuring a time slot alignment of the first wireless station to match a time slot alignment of the second wireless station.

8. A multi-link device for sending data on a wireless network, comprising: a first wireless station associated with a first wireless link of the wireless network; a second wireless station associated with a second wireless link of the wireless network; Memory, used to store data; as well as A processor is operable to: performing independent enhanced distributed channel access on the first wireless link and the second wireless link; Determining that a backoff counter of the first radio link has reached 0; acquiring a transmission opportunity on the first wireless link; determining that the second wireless station has not acquired a transmission opportunity on the second wireless link; delaying a frame exchange sequence on the first radio link until a backoff counter of the second radio link reaches 0; Determining that the backoff counter on the second wireless link has reached 0; In response to determining that the backoff counter on the second radio link has reached 0, acquiring a transmission opportunity on the second radio link; In response to acquiring the transmission opportunity on the second radio link, when physical carrier sensing and virtual carrier sensing indicate that the first radio link is idle, performing a multi-link operation at the multi-link device using the first radio station on the first radio link and using the second radio station on the second radio link; initiating the frame exchange sequence on the first radio link during the transmission opportunity on the first radio link; as well as During the transmission opportunity on the second radio link, a frame exchange sequence is initiated on the second radio link.

9. The multi-link device for sending data on a wireless network as claimed in claim 8, characterized in that: The multi-link device further comprises: receiving timing accuracy information from a second multi-link device, the timing accuracy information indicating that the second multi-link device responded within a time period equal to aSIFSTime+aSignalExtension±TimingErrorMargin measured from the end of transmission of the request frame, The multi-link device cooperates with the second multi-link device to perform the multi-link operation.

10. The multi-link device for sending data on a wireless network as claimed in claim 8, characterized in that: The multi-link operation includes: sending a first multi-user transmission request frame on the first wireless link; and A second multi-user transmission request frame is sent on the second wireless link.

11. The multi-link device for sending data on a wireless network as claimed in claim 10, characterized in that: The first multi-user transmission request frame includes padding for aligning an end time of the first multi-user transmission request frame with an end time of the second multi-user transmission request frame.

12. The multi-link device for sending data on a wireless network as claimed in claim 10, characterized in that: The first multi-user transmission request frame includes a padding field set according to an expected channel access delay of the second wireless station.

13. A method for sending data on a wireless network by a multi-link device, comprising: Independent enhanced distributed channel access is performed at a multi-link device on a first wireless link and a second wireless link, wherein the multi-link device comprises: a first wireless station associated with the first wireless link; and a second wireless station associated with the second wireless link; Acquire a transmission opportunity on the first wireless link; Performing physical carrier sensing and virtual carrier sensing on the first radio link during a time interval aSlotTime; delaying channel access to the first wireless link until the second wireless station obtains a transmission opportunity on the second wireless link to align time slot boundaries for performing multi-link operations on the first wireless link and the second wireless link; and When the physical carrier sensing and the virtual carrier sensing indicate that the first radio link is idle, during the transmission opportunity on the first radio link and the transmission opportunity on the second radio link, the multi-link operation is performed on the multi-link device using the first radio link and the second radio link.

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