Patent Description:
Wireless communication systems can include a network of one or more access points (APs) that communicate with one or more wireless stations (STAs). An AP may emit radio signals that carry management information, control information or user data to one or more STAs. A STA may transmit radio signals to an AP in the same frequency channel using a technique such as time division duplexing (TDD) or in a different frequency using a technique such as frequency division duplexing (FDD).

Institute of Electrical and Electronics Engineers (IEEE) <NUM> specifies a specification for a wireless local area network (WLAN) over radio channels in license-exempt bands. The basic unit of a WLAN is a basic service set (BSS). An infrastructure BSS may include the BSS with stations through associating with an Access Point (AP) to connect to the wired network or Internet. In an infrastructure BSS, both an access point and a station may share the same frequency channel via using Carrier Sensing Multiple Access with Collision Avoidance (CSMA/CA) technology, a kind of TDD mechanism, for multiple access and data transmission.

This document discloses methods, systems, and devices related to digital wireless communications, and more specifically, to techniques related to utilizing multiple wireless connection links between a wireless station and an access point to transmit user data to reduce the access delay, improve transmission reliability and increase transmission throughput.

In one exemplary aspect, a method for wireless communication includes receiving an indication message from a network node, the indication message indicating that the network node is capable of transmitting information over one or more wireless links. The method also includes transmitting a first request message to the network node, wherein the network node associates the station to the one or more wireless links based on receiving the first request message.

In another exemplary embodiment, a method for wireless communication includes transmitting an indication message to a station, the indication message indicating that the network node is capable of transmitting information over at least one wireless link. The method also includes receiving a first request message including multi-link capability information to the network node. The method also includes associating one or more wireless links with the station based on the multi-link capability information.

In another exemplary aspect, a wireless communications apparatus comprising a processor is disclosed. The processor is configured to implement a method described herein.

In yet another exemplary aspect, the various techniques described herein may be embodied as processor-executable code and stored on a computer-readable program medium.

The details of one or more implementations are set forth in the accompanying attachments, the drawings, and the description below.

Wireless local area communication is fast becoming a popular mechanism to communicate with each other directly or via a network such as the internet. Multiple wireless devices (e.g., smartphones, tablets, etc.) may attempt to transmit and receive data on a shared communication spectrum in an environment (e.g., airport, homes, buildings, sports venues, etc.). Additionally, wireless devices (e.g., sensors, cameras, control units, etc.) are increasingly utilized in networks for various applications (e.g., factory automations, vehicle communications etc.).

In some cases, transmission of data is based on an air interface as specified by the Institute of Electrical and Electronics Engineers (IEEE), standard <NUM> series. In this specification, devices may share a transmission medium that include a certain set of rules. In IEEE <NUM>, the basic service set (BSS) is a building block of a Wireless Local Area Network (WLAN). Wireless stations (also called stations) associated in the radio coverage area may establish a BSS and provide the basic service of a WLAN.

IEEE <NUM> specifies wireless access protocols for operation on a license exempt and/or shared spectrum. A wireless station can operate on a channel in license exempt frequency band (e.g., <NUM> or <NUM>), or shared frequency band with other services (e.g., <NUM>).

When operating on a license exempt or shared spectrum, transmission and reception of wireless messages may be unreliable due to interference from other stations located within the same coverage area, such as hidden node transmissions or "visible" nodes attempting to utilize the same shared communication medium for transmissions.

The device operated on the unlicensed frequency band utilizes on the carrier sensing multiple access with collision avoidance (CSMA/CA) mechanism to control the multiple medium access based on IEEE802. <NUM> specification. Each station may implement a CSMA/CA function. Before access to the wireless medium, the station senses the medium occupancy using CSMA/CA. If the station determines that the medium is busy, it waits and retries sensing the medium at a later time. If the station senses the medium in idle, the station may wait for some inter frame space (IFS) and then enter the contention window (CW). In order to support multiple stations to access to the medium, each station may backoff a random time before transmitting over the medium to reduce the collision and distribute the medium access evenly. The backoff time may be defined as <MAT>.

Where Random ( ) = Pseudo random integer uniformly distributed over the interval [<NUM>, CW], and CW is an integer: <MAT>.

The existing CSMA/CA mechanism specified in IEEE <NUM> may include a significant access delay in each transmission and medium utilization efficiency. When a large number of stations share the same medium and are going to transmit simultaneously, the CSMA/CA mechanism may cause the unreliable transmissions (e.g., more transmission packet loss, longer access delay, and larger jittering in an unstable radio environment). Such unreliable transmissions may create a decreased user experience and limit the performance of applications that require low latency and high reliability over an IEEE802. <NUM> access network.

In some cases, as the IEEE802. <NUM> specification allows for one station to associate with one access point over one wireless link, it may be difficult for the station to receive a reliable transmission when this wireless link is congested or interfered, ether at the station side or the access point side. In addition, a wireless station and access point may not be able to communicate each other if the associated wireless link is busy.

This patent document describes techniques to reduce the access latency, improve transmission reliability, and increase transmission throughput in WLAN networks by implementing a mechanism to utilize and control the multi-link (ML) communications over multiple wireless channels.

<FIG> illustrates an example infrastructure BSS. The infrastructure may include multiple ML stations, e.g. ML-STA1 <NUM> and ML-STA2 <NUM>. Each station may be in the coverage of a first ML access point ML-AP1 <NUM> and/or a second ML access point ML-AP2 <NUM>, which form the infrastructure ML-BSS: ML-BSS1 and ML-BSS2. ML access points ML-AP1 <NUM> and ML-AP2 <NUM> may be interconnected via a switch through a distribution system (DS) to form a ML-BSS <NUM> coordinated via a ML-BSS controller <NUM>.

In some embodiments, a ML station (e.g., ML-STA1 <NUM>) with multiple radios can operate multiple channels (or OFDMA channels) in the same frequency band or a different channel to establish multi-links (ML) for communication with a ML PA (e.g., ML-AP1 <NUM>). The ML station can associate with one or more ML access points in the ML-BSS coverage to establish ML connections.

In some embodiments, the ML-AP and ML-STA can leverage the joint or selective transmission modes over one or multi-links (e.g. radio frequency channels) to reduce the access latency, improve the transmission reliability and/or increase the transmission throughput via the control of a ML-STA (e.g., ML-STA1 <NUM>), a ML-AP (e.g. ML-AP2) and/or coordinated by the ML-MBSS Controller <NUM>. A ML communication may include bi-directional transmission between a ML-STA and a ML-AP via part or all of the ML-links between them. It may have some different modes.

A joint ML downlink transmission mode refer to the operation that one or more ML-APs transmit the same PPDU to the ML-STA over MLs at the same time. The ML-STA may combine the received signals in the baseband to improve the signal-to-noise-ratio (SINR) of received signals for increasing the reliability of transmissions or select the best signal from the multiple received signals in the MAC layer. A joint ML uplink transmission mode may refer to that a ML-STA transmits the same PPDU to a ML-AP over MLs at the same time. The ML-AP may combine the received signals in the baseband to improve the signal-to-noise-ratio (SINR) of received signals or select the best signal from the multiple received signals in the MAC layer for increasing the reliability of transmissions.

A selective ML downlink transmission mode may refer to the operation that ML-AP1 <NUM>, or ML-AP2 <NUM> or both transmit a downlink PPDU to a ML-STA <NUM> over one of ML. The ML-STA <NUM> may selectively receive the transmission from either ML-AP1 <NUM> or ML-AP2 <NUM> over the MLs. The selective ML uplink transmission mode may refer to that a ML-STA <NUM> transmits an uplink PPDU to one or more ML-AP over one of ML connections. The ML-AP <NUM> may receive the transmission from the ML-STA <NUM> over the MLs, optionally coordinated by the ML-BSS controller <NUM>. The selective ML transmission may be used by the wireless station or access point to reduce the access latency via selecting the first available link among ML connections for the transmission.

A simplex ML transmission mode may refer to the operation that different ML PPDUs can be concurrently transmitted by the ML-AP <NUM> (or ML-STA <NUM>), or can be concurrently received by the ML-STA <NUM> (or ML-AP <NUM>). But it may be unable to concurrently transmit a ML PPDU by the ML-STA <NUM> (or ML-AP <NUM>) and receive another ML PPDU by the same ML-STA <NUM> (or ML-AP <NUM>). A duplex ML transmission mode may refer to the operation that a ML PPDU can be transmitted over a ML channel by the ML-STA <NUM> (or ML-AP <NUM>) and a different ML PPDU is received over another channel by the same ML-STA <NUM> (or ML-AP <NUM>) concurrently. The duplex transmission operation provides the most flexible way of communication between ML-STA and ML-AP.

<FIG> illustrate examples of ML station and access point system architecture. In the first embodiment as shown in <FIG>, the ML system 200a consists of a ML-STA <NUM> and a ML-AP <NUM>.

As shown in <FIG>, the ML-STA <NUM> includes ML radios <NUM>, <NUM> and <NUM>. Each ML radio may include an <NUM> PHY and a partial MAC (i.e., a lower MAC (MAC-L)). The ML radio <NUM> may operate on a wireless channel (CH1) to establish a radio link <NUM> to a ML-AP <NUM>. Similarly, the ML radio <NUM> and <NUM> may operate on wireless channels (CH2 and CH3) respectively to establish radio links <NUM>, <NUM> to the ML-AP <NUM>. The ML-STA <NUM> may include ML radio controller <NUM> which may consist of a common <NUM> MAC (i.e., upper MAC (MAC-U)), which may manage the ML operation of the ML-STA <NUM>.

The ML-AP <NUM> may include ML radios <NUM>, <NUM> and <NUM>. Each ML radio may include an <NUM> PHY and a partial MAC (i.e., MAC-L). The ML radio <NUM> may operate on a wireless channel (CH1) to establish a radio link <NUM> to the ML station <NUM>. Similarly, the ML radio <NUM> and <NUM> may operate on wireless channels (CH2 and CH3) respectively to establish radio links <NUM>, <NUM> to the ML-STA <NUM>. The ML-AP <NUM> may utilize a ML radio controller <NUM> which may consist of the common <NUM> MAC (MAC-U) to manage the ML operation of the ML-AP <NUM>.

In the second embodiment as shown in <FIG>, the ML system 200B may include a ML-STA <NUM>, a ML-AP <NUM> and a ML-BSS controller <NUM>.

As shown in <FIG>, the ML-STA <NUM> includes ML radios <NUM>, <NUM> and <NUM>. Each ML radio may include an <NUM> PHY and a partial MAC (i.e., MAC-L). The ML radio <NUM> may operate on a wireless channel (CH1) to establish a radio link <NUM> to a ML-AP <NUM>. Similarly, the ML radio <NUM> and <NUM> may operate on wireless channels (CH2 and CH3) respectively to establish radio links <NUM>, <NUM> to the ML-AP <NUM>. The ML-STA <NUM> may use a ML radio controller <NUM> which may consist of the common <NUM> MAC (MAC-U) to manage the ML operation of the ML-STA <NUM>.

The ML-AP <NUM> may include ML radios <NUM>, <NUM> and <NUM>. Each ML radio may include an <NUM> PHY and a partial MAC, i.e. MAC-L. The ML radio <NUM> may operate on a wireless channel (CH1) to establish a radio link <NUM> to the ML-STA <NUM>. Similarly, the ML radio <NUM> and <NUM> may operate on wireless channels (CH2 and CH3) respectively to establish radio links <NUM>, <NUM> to the ML-STA <NUM>.

The ML-BSS controller <NUM>, which can be integrated with the ML-AP <NUM> or located separately as an individual network node, may coordinate one or more ML radio controller <NUM> for the ML operation of the ML-AP <NUM>.

The ML <NUM>, <NUM> and <NUM> may include wireless protocol links that can operate on radio channels in the same frequency band or different frequency bands, like <NUM>, <NUM> or <NUM> band. They could have the same channel bandwidth, like <NUM>, <NUM>, <NUM>, or <NUM>. They may allow different channel bandwidth combinations, such as <NUM> + <NUM> + <NUM>, or <NUM> + <NUM> + <NUM>, etc..

A ML-STA may turn on a ML radio to listen to the transmissions in the unlicensed frequency band and search for Beacon frames. A ML-STA may turn on multiple ML-radios for fast searching over multiple radio channels simultaneously to reduce the searching time. If the ML-STA acquires a ML Beacon frame, it may need to determine whether it can associate with this ML-AP.

A ML-STA may use the same set of EDCA parameters (e.g. backoff counter, CW, CWmin, CWmax, AIFSN, etc.) for uplink ML transmissions over the primary link and/or the alternate link(s), but may maintain different NAV settings in the primary link and each alternate link. Each backoff counter may correspond to an access category such as Background (AC_BK), Best Effort (AC_BE), Video (AC_VI) or Voice (AC_VO). Initially, the backoff counters may be set to the default values of the contention windows according to their access categories.

The ML-AP <NUM> and ML-STA <NUM> may turn on all the ML radios at same time and keep them always-on for detecting and receiving the signal. However, this may cause much more power consumption, especially for the ML-STA <NUM>. To address this power consumption problem, the ML-STA <NUM> may keep only one ML radio on to listen to signals from the ML-AP <NUM> via automatically switching the operating link and/or inform the change of ML operating channel to the ML-AP <NUM>.

The ML-STA <NUM> may keep tracking the operation of each ML radio. When the ML-STA <NUM> finishes the ML transmissions, it may keep only one ML radio on as the operating link and turn off other ML radios (in the sleep mode) according to the link priority order. For example, ML radio <NUM> is the primary radio with the highest priority, the ML radio <NUM> and <NUM> are the alternate radios with the second priority and third priority. Therefore, the ML-STA may keep the ML radio <NUM> on as the operating link and other ML radios <NUM> and <NUM> off if the CH1 <NUM> is determined to be idle. If the ML-STA determines the CH1 <NUM> to be busy by the ML radio <NUM>, it may turn on the ML radio <NUM> and/or <NUM> to listen to the signals from the ML-AP <NUM> over the channels CH2 <NUM> and/or CH3 <NUM> and turn off ML radio <NUM> to reduce their power consumption.

On the transmitting side, the ML-AP <NUM> may transmit a signal to the ML-STA <NUM>, such as the ML TXOP setup, over:.

Alternatively, the ML-STA <NUM> may send a message to ML-AP <NUM> to request to change the current ML operating channel, and switch to a new one after receiving the response from the ML-AP <NUM>.

When going to send a user data, the ML-STA <NUM> may turn on all ML radios to find all the possible available channels and select the corresponding ones for the ML transmission.

<FIG> illustrates an example of Extremely High Throughput (EHT) Capability IE with the ML Support information. The Information Element <NUM>, as shown in <FIG>, may carry the information of EHT capability information and/or Multi-band operation information. The EHT Capability Info <NUM> may contain the ML Support <NUM> and ML Channel Information <NUM>.

ML Support Information <NUM> may indicate the ML communication capability supported by the ML-AP (or ML-STA), and may include an indication that it does not support ML, an indication that it supports the selective ML transmission mode, an indication that it supports the joint ML transmission mode, an indication that it support the simplex ML transmission mode, and/or an indication that it supports the duplex ML transmission mode.

ML CH Information <NUM> may indicate the ML communication channels. The ML-AP may carry this information in the Beacon frame to indicate the primary channel and all the supported alternate channels. The ML-STA may carry this information in the ML Association Request or ML Re-Association Request to request or change the alternate channel(s) for the ML establishment or ML update. The primary channel and supported alternate channels may be identified by their radio frequency channel numbers.

The Multi-Band Info <NUM> may include the information of ML communication which the ML-AP is operating on. Example channels may include a <NUM>, <NUM>, or <NUM> band.

<FIG> illustrates an example signaling process <NUM> of ML establishment based on association request and response message exchange.

In step <NUM>, as shown in <FIG>, a ML-AP <NUM> may be a ML-AP capable access point. In an embodiment, the ML-AP <NUM> broadcasts the ML Support Information <NUM> in an EHT Capability Information Element of a Beacon frame, or in a Probe Response frame.

In step <NUM>, a ML-STA <NUM> in a ML-BSS coverage area may listen to Beacon or Probe Response frames and determine whether neighbor APs can support the ML feature. If the ML-STA <NUM> receives a Beacon frame and determines that AP(s) is of ML capability, it may send a ML Association Request <NUM> to the ML-AP(s), i.e. ML-AP <NUM> in this example. The ML Association Request <NUM> includes an ML Capability Information with a proposed ML configuration information such as a primary channel and alternate channels of the ML-STA.

The ML-STA <NUM> may include and use a ML Identifier (ML ID) to identify the configuration of ML communication between the ML-STA <NUM> and ML-AP <NUM>, and indicate the ML operating channel for the power saving listening mode in the ML Association Request message.

In step <NUM>, when receiving the ML Association Request from a ML-STA, the ML-AP <NUM> may optionally send an acknowledgement message <NUM> to the ML-STA <NUM> first, and then process the ML Association Request.

In step <NUM>, after the ML association processing is completed, the ML-AP <NUM> may send a ML Association Response <NUM> to acknowledge whether or not the ML association is granted. If granted, the ML-AP <NUM> includes in the ML Association Response the ML configuration with the primary channel and alternate channels information and the ML operating channel indication for the ML-STA <NUM>. If the ML-AP <NUM> operates more than two alternate links, it may selectively assign a set of alternate link(s) to the ML-STA <NUM> so as to distribute user traffic and balance load among the all the multi-links.

In step <NUM>, the ML-STA <NUM> may optionally send an ML Association ACK <NUM> to confirm the ML association with the ML-AP <NUM> if the ML configuration in the ML Association Response message is different from the proposed ML configuration in the ML Association Request message but is accepted by the ML-STA <NUM>.

After the ML association is established, the ML-STA <NUM> may use the EDCA mechanism for the uplink ML transmission over the primary link and/or alternate link(s). The ML-STA <NUM> may use one set EDCA parameters for the MLs, but maintains individual NAV settings for the primary link and each alternate link.

The ML-STA <NUM> may update the established MLs, such as adding a new alternate link or remove an existing alternate link.

In some embodiments, a ML-STA <NUM> may update the alternate link(s) via sending a ML Re-Association Request to the associated ML-AP <NUM>. The alternate link(s) of ML-STA <NUM> may be updated after receiving the ML Re-Association Response from the ML-AP <NUM>.

In some embodiments, a ML-STA <NUM> may disassociate with the ML-AP <NUM> via sending a ML Disassociation Request. The ML association with the ML-AP <NUM> may be then released.

In some embodiments, the ML-STA <NUM> may not receive a Beacon frame from the ML-AP <NUM>, and the ML-STA <NUM> may send a ML Probe Request message for the ML-BSS information. If the ML-AP <NUM> receives the ML Probe Request message, it may respond with a ML Probe Response message within a given time period.

The ML communication can be operated to support different service requirements through the enhanced service class parameters of the MLME SAP primitives. For example, the enhanced service class parameters may include any of:.

The enhanced service parameters can be added to the existing service class attribute or in a new attribute of enhanced service class in MA-UNITDATA. request ().

<FIG> illustrate example utilizing the ML radio processes to support low latency transmission, high reliable transmission and high throughput transmission over the wireless interface.

In a first embodiment, as shown in <FIG>, it illustrates an example 500A of supporting the low latency transmission via MLs. When a ML-STA (or ML-AP) is instructed by the application via setting LL-QoS in the enhanced service class to transmit low latency user data to an associated ML-AP (or ML-STA), it may perform the virtual carrier sensing via ML NAVs on CH1 <NUM>, CH2 <NUM> and CH3 <NUM>. If at least one of those channels is not set by the virtual sensing, the ML-STA (or ML-AP) may simultaneously perform the physical ML-CCA sensing on the channels not set by the ML NAVs to find the earliest available channel(s) for low latency transmission. In this example, the ML-STA (or ML-AP) may find the link <NUM> (CH3) is the earliest available channel among the MLs after the ML backoff counter corresponding to the access category reaches to <NUM> and the ML-CCA detects the CH3 in idle. It can then transmit a PPDU over the link <NUM> on the radio channel CH3.

A second embodiment 500B, as shown in <FIG>, illustrates an example of supporting the high reliable transmission via MLs. When a ML-STA (or ML-AP) is instructed by the application via setting HR-QoS in the enhanced service class to send out user data in the reliable way to an associated ML-AP (or ML-STA), it may perform the virtual carrier sensing via ML NAVs on CH1 <NUM>, CH2 <NUM> and CH3 <NUM>. If at least two of those channels are not set by the virtual sensing, the ML-STA (or ML-AP) may simultaneously perform the physical ML-CCA sensing on those channels not set by the ML NAVs to find the two or more available channels for the reliable transmission. In this example, the ML-STA (or ML-AP) may find the link <NUM> (CH1) and the link <NUM> (CH3) are the two earliest available channels among the MLs after the ML backoff counter corresponding to the access category reaches to <NUM> and the ML-CCA detection detects both CH1 and CH3 idle. It may then transmit the same PPDU of the same sequence number over the link <NUM> and the link <NUM> at the same time.

On the receiving side, the ML-AP (or ML-STA) may perform a selection on the multiple received MPDUs in the MAC layer to get the best quality MPDU according to the channel quality or error checking indication on the link <NUM> and the link <NUM>. The ML-AP (or ML-STA) may combine the received signals from the link <NUM> and the link <NUM> in the ML PHYs to improve the SINR as well.

A third embodiment 500C, as shown in <FIG>, illustrates an example of supporting the high data throughput transmission via MLs. When a ML-STA (or ML-AP) is instructed by the application via setting HT-QoS in the enhanced service class to send out user data in the high throughput to an associated ML-AP (or ML-STA), it may perform the virtual carrier sensing via ML NAVs on CH1 <NUM>, CH2 <NUM> and CH3 <NUM>. If any of those channels are not set by the virtual sensing, the ML-STA (or ML-AP) may perform the physical ML-CCA sensing on those channels not set by the ML NAVs to find all the available channels for the high throughput transmission. The ML-STA (or ML-AP) may continue monitoring the remaining channel availability during the ML transmission(s) and initiate another ML transmission if another link is detected as being available. In this example, the ML-STA (or ML-AP) may first find the link <NUM> (CH3) as available among the three MLs after the ML backoff counter corresponding to the access category reaches to <NUM> and the ML-CCA detects it idle. It then may transmit a PPDU over the link <NUM> (CH3) and continue monitoring other links <NUM> and <NUM>. If the link <NUM> (CH1) is detected idle, the ML-STA (or ML-AP) may transmit a new PPDU of a new sequence number over the link <NUM> (CH1). Similarly, the ML-STA (or ML-AP) may transmit a new PPDU of a new sequence number over the link <NUM> (CH2) once it is detected as idle and the existing ML transmission over CH1 and CH3 are still going on. The MAC-U of the ML-STA (or ML-AP) may coordinate ML transmissions over different channels. As each ML link is operated independently, the transmissions over ML links may not be necessary to end at the same time. If the ML-STA and ML-AP only supports simplex communication mode, a padding may be inserted at the end of the PPDU transmission for alignment. Otherwise, if the ML-STA and ML-AP support duplex ML communication mode, the padding at the end of PPDU may not be necessary and the acknowledgement frame (e.g. BA, ACK, etc.) can be transmitted immediately in the SIFS time after the PPDU transmission completion.

The receiving ML-AP (or ML-STA) of the high throughput traffic can perform the MAC layer aggregation on the received PSDUs. In this way, the ML-STA (or ML-AP) can aggregate more available links to increase the data throughput for the high throughput application.

If the ML transmission succeeds, the ML-STA (or ML-AP) may reduce the contention window size corresponding to the access category and reset the backoff counter to the CW. If the ML transmission fails, the ML-STA (or ML-AP) may double the contention window size corresponding to that access category and reset the backoff counter to the CW. Then, the ML-STA (or ML-AP) re-transmits the failed PPDU with the same sequence number over the MLs.

In order to support the ML communication, the IEEE802. <NUM> protocol reference architecture may need to be enhanced to separate the MAC layer into the upper MAC (i.e. MAC-U) and the lower MAC (i.e. MAC-L).

<FIG> illustrates an example protocol reference architecture for support of ML communication. The MAC-U <NUM>, on the transmission side (TX), may consist of some functions such as A-MSDU aggregation, PS Defer Queuing, Sequence Number Assignment, MSDU Integrity Protection, Fragmentation, Packet Number Assignment, MPDU Encryption and Integrity Protection.

The MAC-U <NUM>, on the receiving side (RX), may consist of functions such as A-MSDU aggregation, MSDU Integrity Protection, Defragmentation, Replay Detection, Block Ack Buffering and Reordering, MPDU Decryption and Integrity Check.

The MAC-U <NUM> can be implemented within ML-STA <NUM> or ML-AP <NUM> as shown in <FIG>. It may be located in a separate network entity like ML-BSS Controller <NUM> in <FIG>.

The MAC-L <NUM>, on the transmission side (TX), may be associated to a PHY of the ML radio which is operating on a frequency channel as shown in <FIG>. MAC-L <NUM> may consist of some functions such as MPDU Header and CRC Creation, MPDU Aggregation. The ML radio (including MAC-L <NUM>) can be implemented within the same ML-STA <NUM> or the same ML-AP <NUM>, as shown in <FIG>.

The MAC-L <NUM>, on the receiving side (RX), is associated to a PHY of the ML radio which is operating on a frequency channel, as shown in <FIG>. MAC-L <NUM> may consist of some functions such as Duplicate Removal, HARQ-ACK/HARQ-NACK/BACK/ACK, Address Filtering, MPDU Header and CRC Validation, MPDU De-aggregation. The ML radio (including MAC-L <NUM>) can be implemented within the ML-STA <NUM> or the ML-AP <NUM> as shown in <FIG>.

<FIG> illustrate example signaling processes for ML transmission protection establishment for ML transmissions. The ML-AP <NUM> and ML-STA <NUM> may have established the MLs through the ML association and response message exchanges. The ML-AP <NUM> and ML-STA <NUM> may agree that the primary link <NUM> is operating on a radio channel with the maximum channel bandwidth <NUM> and the alternate link <NUM> is operating on another radio channel with the maximum channel bandwidth <NUM>, as an example.

In a first embodiment, as shown in <FIG>, a ML transmission protection may be established when the ML primary channel is busy and the ML alternate channel is idle. In a second embodiment, as shown in <FIG>, a ML transmission protection may be established when both ML primary and alternate channels are idle.

In step <NUM>, the MAC-U <NUM> may receive a transmission request from the application with an enhanced service class such as QoS-LL, QoS-HR or QoS-HT. It may instruct each ML MAC-L <NUM> to perform virtual carrier sensing with NAVs to get possibly available ML channels. The ML MAC-L <NUM> may report the available ML channel to the ML MAC-U <NUM>. Based on the enhanced service class requirement and the report from each ML MAC-L <NUM>, the ML MAC-U <NUM> may then instruct the corresponding ML radio (e.g. ML MAC-L/PHY) to perform the ML physical carrier sensing on those possibly available channel(s) using the same EDCA parameters such as backoff counter settings of the access categories, etc. If the ML channel is sensed as idle by the corresponding ML radio and the backoff counter of the access category reaches to <NUM>, the ML MAC-L <NUM> may report to the ML MAC-U <NUM> with the ML channel information.

In step <NUM>, the ML MAC-U <NUM> may instruct the corresponding ML radio to transmit the RTS message over the ML channels. The RTS may optionally include the information of ML channels to be used in the following transmissions when the transmitting station needs to select the best channel(s) within the multiple available channels, as an example. In the first embodiment in <FIG>, the RTS is transmitted over two <NUM> bandwidth channels in alternate link <NUM> as those two <NUM> bandwidth channels are detected as idle. In the second embodiment in <FIG>, both primary link <NUM> and alternate link <NUM> are detected as idle. Therefore, the RTS can be transmitted over two <NUM> bandwidth channels in the primary link <NUM> and two <NUM> bandwidth channels in the alternate link <NUM>.

In step <NUM>, after receiving the RTS request, the receiving ML station (either ML-STA or ML-AP) may send a CTS over those ML channels to confirm the MLs. The CTS may optionally include the information of ML channels to confirm the channel(s) to be used in the following transmissions. The ML-STA and ML-AP may use the RTS and CTS to establish a ML TXOP for the following ML transmissions over those ML channels. Other STAs that receive RTS and/or CTS over those channels may set their NAVs to prevent from sending data during the ML TXOP period.

In step <NUM>, the requesting station transmits the ML PPDU over the ML channels. In the first embodiment in <FIG>, a ML PPDU may be sent over the earliest available ML channel for the low latency application. In the second embodiment in <FIG>, the same ML PPDU are sent over the primary link <NUM> and the alternate link <NUM> for the reliable application, the different ML PPDUs over the primary link <NUM> and the alternate link <NUM> respectively for the high throughput application.

After receiving the ML PPDU(s), the receiving station may combine the received signals in the ML PHYs to improve the SINR or select the best quality data packet in MAC-U for the reliable transmission or perform the packet aggregation in the MAC-U for the high throughput application.

In step <NUM>, the receiving station may transmit an acknowledgement if the received MPDU succeeds. If the transmitting station does not receive the acknowledgement in a given time, it may declare the ML transmission a failure and will re-transmit the failed MSDU after the re-transmission timer expires.

<FIG> illustrates an example MAC header format <NUM> for an ML control frame. The MAC header format for a ML control frame may include, for example, a BA/ACK, RTS/CTS or ML Channel Switch Request/Response.

The MAC header may include frame control (FC) field to indicate the MAC frame type and other information about the frame. The MAC header may include a transmission duration of this frame, and any of a receiving address (RA), a transmission address (TA), and a destination address (DA).

The MAC header may include a ML channel switch information (ML CH SWITCH INFO) field <NUM> to indicate the new ML operating channel and/or the time of switching the ML operating channel for the future ML. communications. The ML-STA may use this message to request switching to a new ML operating channel for future ML communications.

<FIG> illustrates an example signaling process <NUM> for switching the ML operating channel.

In step <NUM>, the ML-STA <NUM> may send a ML Channel Switch Request message <NUM> to the ML-AP <NUM> to request change of the ML operating channel in some situation, like the current ML operating channel is experiencing an interference or over loaded. The ML Channel Switch Request message <NUM> carries the new ML operation channel information <NUM>.

In step <NUM>, the ML-AP <NUM> receives the ML Channel Switch Request message <NUM> and processes the request. The ML-AP <NUM> sends the ML Channel Switch Response message <NUM> to indicate whether or not the request is granted and include the ML operation channel information <NUM> to confirm the new ML operation channel and/or switching time.

If the request is granted, the ML-STA <NUM> shall switch the ML operation channel to the new one at the switching time if it is included, or immediately if not included. Otherwise if the request is not granted, the ML-STA <NUM> shall keep the exiting ML operating channel for the future ML communications.

<FIG> illustrates a block diagram of a method for multi-link operation. In a first exemplary embodiment, a method includes receiving, by a station, an indication message from a network node indicating that the network node is capable of transmitting information over one or multiple wireless links (block <NUM>). The indication message may include information identifying that an access point is capable of multi-link transmission, as illustrated in <FIG>, for example.

<FIG> is a block diagram representation of a portion of a hardware platform. A hardware platform <NUM> such as a network device or a base station or a wireless device can include processor electronics <NUM> such as a microprocessor that implements one or more of the techniques presented in this document. The hardware platform <NUM> can include transceiver electronics <NUM> to send and/or receive wired or wireless signals over one or more communication interfaces such as antenna <NUM> or a wireline interface. The hardware platform <NUM> can implement other communication interfaces with defined protocols for transmitting and receiving data. The hardware platform <NUM> can include one or more memories (not explicitly shown) configured to store information such as data and/or instructions. In some implementations, the processor electronics <NUM> can include at least a portion of the transceiver electronics <NUM>. In some embodiments, at least some of the disclosed techniques, modules or functions are implemented using the hardware platform <NUM>.

From the foregoing, it will be appreciated that specific embodiments of the presently disclosed technology have been described herein for purposes of illustration, but that various modifications may be made without deviating from the scope of the invention. Accordingly, the presently disclosed technology is not limited except as by the appended claims.

A propagated signal is an artificially generated signal, e.g., a machine-generated electrical, optical, or electromagnetic signal, which is generated to encode information for transmission to suitable receiver apparatus.

While this patent document contains many specifics, these should not be construed as limitations on the scope of any invention or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular inventions. Certain features that are described in this patent document in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable sub combination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a sub combination or variation of a sub combination.

Claim 1:
A method for wireless communication, comprising:
receiving, by a station, an indication message from a network node, the indication message indicating that the network node is capable of transmitting information over one or more wireless links;
transmitting, by the station, a first request message to the network node,
wherein network node associates the station to the one or more wireless links based on receiving the first request message, and
wherein the first request message includes a multi-link association request indicating a request to establish a connection to the one or more wireless links; and
separating, by the station, a media access control, MAC, into an upper MAC part and a lower MAC part,
wherein the lower MAC part associated with a physical layer protocol of multi-link radio controlling physical layer operations to either transmit or receive a radio signal over a frequency channel with an Enhanced distributed channel access, EDCA, mechanism, and
wherein the upper MAC part coordinates operation of the lower MAC part by configuring EDCA parameters in the lower MAC part and performs selecting or aggregation of received packets from the one or more wireless links.