WO2022099706A1

WO2022099706A1 - Device and method for improving low latency services

Info

Publication number: WO2022099706A1
Application number: PCT/CN2020/129135
Authority: WO
Inventors: Oren Kedem; Yunping LYU; David Bachar; Bo Yang; Wei Qiu
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2020-11-16
Filing date: 2020-11-16
Publication date: 2022-05-19
Also published as: CN116530156A

Abstract

The present disclosure relates to a random access procedure. To provide an efficient resource allocating method for clients with QoS requirements, the disclosure proposes a first network device being configured to: determine one or more group AIDs, for one or more groups of second network devices; determine one or more time-frequency resources, each time-frequency resource being associated with one group AID, wherein each time-frequency resource is allocated to a group of second network devices with that group AID; and send a trigger frame to the one or more groups of second network devices, wherein the trigger frame is indicative of one or more group AIDs, and the time-frequency resources associated with the one or more group AIDs. Further, this disclosure also proposes a second network device being configured to receive the trigger frame from a first network device; and contend time-frequency resources obtained based on the trigger frame.

Description

DEVICE AND METHOD FOR IMPROVING LOW LATENCY SERVICES

TECHNICAL FIELD

The present disclosure relates generally to random access procedures in wireless transmissions, and more particularly to resource allocations. The disclosure proposes a device and a method for scheduling uplink transmissions in an effective and flexible manner.

BACKGROUND

Industry 4.0 targets to improve connectivity by many parameters (e.g. flexibility, versatility, efficiency etc) . One of the most important improvements is the reduction of network latency as required by Ultra Reliable Low Latency Communication (URLLC) use cases. As for today, Wireless Local Area Network (WLAN) is the common wireless technology for existing non-critical applications in the manufacturing industry, hence it is expected to support URLLC requirements as well.

Current solutions embedded in IEEE 802.11ax standard (Wi-Fi 6) are insufficient in providing a client the required medium access time to transmit its latency sensitive data. The client is either required to contend the medium for long time periods, or to wait for Orthogonal Frequency-division Multiple Access (OFDMA) unicast allocations made by Access Point (AP) , in order to transmit its data. This results in a high end-to-end latency. End-to-end latency is defined as the time that it takes to transfer an amount of data from a source endpoint device to a destination endpoint device.

Wi-Fi 6 link access works on top of the legacy Carrier-sense Multiple Access with Collision Avoidance (CSMA/CA) mechanism named Enhanced Distributed Channel Access (EDCA) . In particular, any client (e.g., stations (STAs) ) or AP that requires to transmit, performs a random backoff procedure. When the random backoff procedure is successfully completed, the client or the AP is allowed to attempt the transmission. When the AP wins the medium contention over other clients, it may utilize an efficient OFDMA link access method based on a frame-based transmission. An OFDMA frame contains data to/from different users while various frame Orthogonal Frequency-division Multiplexing (OFDM) tones are assigned to the users for the entire frame duration. Scheduling uplink (UL) transmission via the OFDMA link access is done with a trigger frame sent before the designated OFDMA frame. After the AP wins the medium contention, it sends a trigger frame to allocate resources for all the clients participating in upcoming frame exchange. Hence, to achieve low latency, it is preferred that the AP will access the channel with OFDMA allocated by the AP for many users, but not EDCA used only by one client.

However, the AP doesn’t always know which client has data for transmission, hence it cannot allocate the tones in the optimal manner. One of Wi-Fi 6 solutions to accommodate is a method called “UL OFDMA-based random access” (UORA) in which AP indicates that group of tones intended for the usage of all clients. In this case, clients contend the indicated tones with an additional random access backoff mechanism. The OFDMA tones allocated for all clients are named Random-Access Resource-Unit (RA-RU) . However, current solutions are still not optimal or efficient for clients with Quality of Service (QoS) requirements, particularly for low latency services.

SUMMARY

In view of the above-mentioned deficiencies, embodiments of the present disclosure aim to introduce an improved solution for allocating resources to clients in an effective and flexible manner. In particular, an objective is to provide medium link access privileges for clients with QoS requirements. Another objective is to prioritize low latency sensitive traffic over other traffic.

The objective is achieved by embodiments as provided in the enclosed independent claims. Advantageous implementations of the embodiments are further defined in the dependent claims.

A first aspect of the disclosure provides a first network device, configured to determine one or more group association identifiers (AIDs) , for one or more groups of second network devices, each group comprising one or more second network devices; determine one or more time-frequency resources, each time-frequency resource being associated with one group AID, wherein each time-frequency resource comprises one or more resource units (RUs) , and wherein each time-frequency resource is allocated to a group of second network devices with that group AID; and send a trigger frame to the one or more groups of second network devices, wherein the trigger frame is indicative of one or more group AIDs, which are assigned to the one or more groups of the second network devices, and the time-frequency resources associated with the one or more group AIDs.

Conventionally in UORA random access, AID that is either 0 or 2045 can be used to indicate associated or unassociated clients or STAs, respectively. Embodiments of this disclosure propose a newly designed group AID for grouping STAs that may share common link access characteristics, e.g., STAs with low latency requirements. In this way, dedicated RUs can be allocated for a particular group of STAs only. STAs in this group thus only need to contend the allocated RUs with STAs in the same group, instead of with all STAs.

In an implementation form of the first aspect, the first network device is further configured to obtain an association requirement from each second network device of the one or more groups of second network devices; and determine the one or more group AIDs for the one or more groups of the second network devices based on the one or more association requirements.

STAs with association requirements may inform the first network device their requirements during association procedures or via traffic specification procedures (TSPEC) . In response, the first network device may group several STAs that share common link access, by assigning them the same group AID.

In an implementation form of the first aspect, the association requirement comprises: a QoS requirement, of the second network device; one or more access categories (ACs) , each comprising one or more traffic identifiers (TIDs) , of the second network device; and/or one or more traffic stream identifiers (TSIDs) , of the second network device.

QoS requirements from a STA may indicate that the STA has low latency services. Notably, priority levels of traffic in EDCA are called ACs. ACs may be used to classify different types of traffic. Currently, four ACs are defined in standards: Best effort (BE) , Background (BK) , Video (VI) , and Voice (VO) . TSID may also be used to classify traffic apart from AC.

In an implementation form of the first aspect, the first network device is further configured to obtain a QoS requirement from each second network device of the one or more groups of second network devices; and determine the same group AID for the second network devices with the same QoS requirement.

Optionally, the association requirement of STAs may be a QoS requirement. In response to the obtained QoS requirements of STAs, the first network device may group several QoS STAs with low latency data requirements by assigning these STAs with a dedicated group AID.

In an implementation form of the first aspect, the first network device is further configured to obtain one or more ACs and/or one or more TSIDs from each second network device of the one or more groups of the second network devices; and determine the same group AID for the traffic streams of the second network devices of the one or more groups of the second network devices with the same AC, and/or with the same TSID.

Optionally, the association requirement of STAs may be related to different types of traffic. The first network device may assign specific group AIDs for different ACs or for different TSIDs.

In an implementation form of the first aspect, each group AID is further associated with one or more contention windows (CWs) , wherein the first network device is further configured to: determine a minimum value and a maximum value of each of the one or more CWs; and provide each of the one or more minimum values and the one or more maximum values to the group of second network devices with the respective associated group AID.

Optionally, different sizes of CW (defined by CWmin/CWmax) may be set for different groups of STAs. For instance, different CWs may be set for different ACs. In particular, different CWmin/CWmax may be used to prioritize one type of traffic over the others. Similarly, different CWs may also be set for QoS clients with different latency requirements.

In an implementation form of the first aspect, in response to the association requirement, the first network device is further configured to send an association response to the second network device that sends the association requirement, wherein the association response is indicative of the minimum value and the maximum value of the CW associated with each of the one or more group AIDs.

Information regarding which CWmin/CWmax is associated with which group AID may be delivered in frames like Probe/Association Response.

A second aspect of the disclosure provides a second network device, wherein the second network device is configured to: receive a trigger frame from a first network device, wherein the trigger frame is indicative of one or more AIDs, which are assigned to one or more groups of second network devices, and one or more time-frequency resources, each time-frequency resource being associated with one group AID, wherein each time-frequency resource comprises one or more RUs, wherein each time-frequency resource is allocated to a group of second network devices with that group AID; obtain one or more group AIDs that are assigned to the second network device, and one or more time-frequency resources that are allocated to the second network device, based on the trigger frame; and contend the one or more time-frequency resources with one or more other second network devices that are assigned with the same one or more group AIDs.

Embodiments of this disclosure further propose a second network device, which is a client of the first network device, and can operate accordingly as described in first aspect and its implementation forms.

In an implementation form of the second aspect, the second network device is further configured to provide an association requirement to the first network device, wherein the one or more group AIDs assigned to the second network devices are determined based on the association requirement.

For instance, if the second network device has low latency services, it may send the association requirement, in this case the low latency requirement, to the first network device.

In an implementation form of the second aspect, the association requirement comprises: a QoS requirement, of the second network device; one or more ACs, each comprising one or more TIDs, of the second network device; and/or one or more TSIDs, of the second network device.

In an implementation form of the second aspect, the second network device is further configured to provide the QoS requirement of the second network device to the first network device; and contend the one or more time-frequency resources with the one or more other second network devices that have the same QoS requirement.

In this way, the second network device only need to contend the assigned RUs with other STAs with the same QoS requirement, but not with all STAs. Thus, the low latency services of the second network device may have privilege to access medium link.

In an implementation form of the second aspect, the second network device is further configured to provide the one or more ACs, and/or the one or more TSIDs from the second network device to the first network device; and for a particular traffic stream of the second network device, contend the one or more time-frequency resources with traffic streams of the one or more other second network devices with the same AC, and/or with the same TSID.

In this way, a particular type of traffic on the second network device only need to contend the assigned RUs with other traffics with the same AC or TSID, but not with all traffic. Thus, the traffic with higher priority may have privilege to access medium link.

In an implementation form of the second aspect, the second network device is further configured to maintain a backoff counter associated with each of the one or more group AIDs, wherein each backoff counter is set with an initial value.

Possibly, each STA may manage different backoff counters for different RA-RU categories (e.g., different services) indicated by different AID or group AIDs. It is also possible that one backoff counter is set for all RA-RU categories.

In an implementation form of the second aspect, when a time-frequency resource associated with a particular group AID is obtained, the second network device is further configured to decrement the backoff counter associated with the group AID by a number of the one or more RUs of the time-frequency resource.

For instance, if three RA-RUs are allocated for the group that the second network device belongs to, the backoff counter associated with that group will be decrement by three.

In an implementation form of the second aspect, the second network device is further configured to select a RU from the one or more RUs of the time-frequency resource, when the backoff counter decrements to zero; and transmit one or more frames on the selected RU.

If the backoff counter reaches zero, the second network device is free to transmit its pending frames. Optionally, the second network device will randomly select a RU from the RUs allocated for its group.

In an implementation form of the second aspect, the second network device is further configured to select a new value for the backoff counter after transmitting the one or more frames.

In an implementation form of the second aspect, the second network device is further configured to obtain a minimum value and a maximum value of a CW associated with each of the one or more group AIDs, to the second network device.

In an implementation form of the second aspect, the second network device is further configured to receive an association response from the first network device, wherein the association response is indicative of the minimum value and the maximum value of the CW associated with each of the one or more group AIDs.

As previously mentioned, information regarding which CWmin/CWmax is associated with which group AID may be delivered by the first network device in frames like Probe/Association Response.

In an implementation form of the second aspect, the second network device is further configured to set an initial value of a backoff counter associated with a particular group AID to a value range from 0 to two of the power of the minimum value of the CW associated with the group AID.

For instance, if CWmin is set to 3 and CWmax is set to 9 (CWmin/CWmax is associated with the same group AID) , the backoff counter associated with that group ID may be initially set to 8 (2 ³) . Notably, by setting different CWmin/CWmax for different groups of STAs, particularly STAs with different QoS requirements or with different ACs, the low latency services can be prioritized over other services, or one type of traffic can be prioritized over the other traffic.

In an implementation form of the second aspect, the second network device is further configured to select a new value range from 0 to two of the power of the minimum value of the CW plus one, for the backoff counter, when a collision happens.

As in the same example as above described, if a collision happens, the backoff counter may be set to 16, i.e., 2 ⁴.

A third aspect of the disclosure provides a method performed by a first network device, the method comprising: determining one or more group AIDs, for one or more groups of second network devices, each group comprising one or more second network devices; determine one or more time-frequency resources, each time-frequency resource being associated with one group AID, wherein each time-frequency resource comprises one or more RUs, and wherein each time-frequency resource is allocated to a group of second network devices with that group AID; and sending a trigger frame to the one or more groups of second network devices, wherein the trigger frame is indicative of one or more group AIDs, which are assigned to the one or more groups of the second network devices, and the time-frequency resources associated with the one or more group AIDs.

Implementation forms of the method of the third aspect may correspond to the implementation forms of the first network device of the first aspect described above. The method of the third aspect and its implementation forms achieve the same advantages and effects as described above for the first network device of the first aspect and its implementation forms.

A fourth aspect of the disclosure provides a method performed by a second network device, the method comprising: receiving a trigger frame from a first network devices, wherein the trigger frame is indicative of one or more group AIDs, which are assigned to one or more groups of second network devices, and one or more time-frequency resources, each time-frequency resource being associated with one group AID, wherein each time-frequency resource is allocated to a group of second network devices with that group AID, wherein each time-frequency resource comprises one or more RUs; obtaining one or more group AIDs that are assigned to the second network device, and one or more time-frequency resources that are allocated to the second network device, based on the trigger frame; and contending the one or more time-frequency resources with one or more other second network devices that are assigned with the same one or more group AIDs.

Implementation forms of the method of the fourth aspect may correspond to the implementation forms of the second network device of the second aspect described above. The method of the fourth aspect and its implementation forms achieve the same advantages and effects as described above for the second network device of the second aspect and its implementation forms.

A fifth aspect of the disclosure provides a computer program product comprising a program code for carrying out, when implemented on a processor, the method according to the third aspect and any implementation forms of the third aspect, or the fourth aspect and any implementation forms of the fourth aspect.

It has to be noted that all devices, elements, units and means described in the present application could be implemented in the software or hardware elements or any kind of combination thereof. All steps which are performed by the various entities described in the present application as well as the functionalities described to be performed by the various entities are intended to mean that the respective entity is adapted to or configured to perform the respective steps and functionalities. Even if, in the following description of specific embodiments, a specific functionality or step to be performed by external entities is not reflected in the description of a specific detailed element of that entity which performs that specific step or functionality, it should be clear for a skilled person that these methods and functionalities can be implemented in respective software or hardware elements, or any kind of combination thereof.

BRIEF DESCRIPTION OF DRAWINGS

The above described aspects and implementation forms of the present disclosure will be explained in the following description of specific embodiments in relation to the enclosed drawings, in which

FIG. 1 shows a conventional UORA procedure.

FIG. 2 shows a first network device according to an embodiment of the disclosure.

FIG. 3 shows a second network device according to an embodiment of the disclosure.

FIG. 4 shows a message flow according to an embodiment of the disclosure.

FIG. 5 shows an improved UORA procedure according to an embodiment of the disclosure.

FIG. 6 shows a message flow according to an embodiment of the disclosure.

FIG. 7 shows an improved UORA procedure according to an embodiment of the disclosure.

FIG. 8 shows a method according to an embodiment of the disclosure.

FIG. 9 shows a method according to an embodiment of the disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Illustrative embodiments of methods, devices, and program product for MU transmissions in a communication system are described with reference to the figures. Although this description provides a detailed example of possible implementations, it should be noted that the details are intended to be exemplary and in no way limit the scope of the application.

Moreover, an embodiment/example may refer to other embodiments/examples. For example, any description including but not limited to terminology, element, process, explanation and/or technical advantage mentioned in one embodiment/example is applicative to the other embodiments/examples.

To introduce this disclosure, the conventional UORA random access procedure is first described here. In UORA random access, a trigger frame from AP allocates RUs for RA-RU through indication of specific AID (i.e., RA-RU AID is 0 or 2045) , which can be used by associated and unassociated STAs respectively.

UORA random access allocation is performed as follows:

1. OFDMA Backoff Count (OBO) is set to a random value range 0 to CW OFDMA (CWO) advertised by AP.

2. STA decrements its non-zero OBO value by 1 for every RA-RU.

3. STA with OBO decremented to 0 randomly selects any one of the assigned RUs for random access, and transmits its frame (s) .

FIG. 1 shows an existing UORA procedure (according to Wi-Fi 6 standard) in which a client may attempt its transmission in OFDMA UORA allocation.

In the example as shown in FIG. 1, before Trigger frame 1 was sent by AP, high-efficiency (HE) STA 1, STA 2, STA 3 and STA 4 had initial OBO values of 3, 5, 4 and 2, respectively.

Upon receiving Trigger frame 1:

● STA 4, which is associated with the AP ( “Associated, AID = 3” as shown in FIG. 1) and has pending frames for the AP, is allocated a dedicated RU (RU6) . Thus, STA 4 does not contend for RA-RUs and instead transmits its pending frames on RU6.

● STA 1 and STA 2, both associated with the AP ( “Associated, AID = 5” and “Associated, AID = 7” as shown in FIG. 1) and having pending frames for the AP, decrement their respective OBO counters by the number of eligible RA-RUs indicated in Trigger frame 1, i.e., three RA-RUs for associated STAs. As shown in Trigger frame 1, RU1, RU2 and RU3 with AID 0 indicate that these three RUs are for associated STAs, i.e., STA 1 and STA 2. Since STA 1’s OBO counter decrements to 0, it transmits its pending frames on RU2 that it randomly selects from the eligible set of RUs (i.e., RU1, RU2, and RU3) . Since STA 2’s OBO counter decrements to a nonzero value, it maintains the new OBO value (2) until it receives a later Trigger frame carrying RA-RUs for associated STAs.

● STA 3, which is not associated with the AP ( “Unassociated” as shown in FIG. 1) but has a pending frame for the AP, decrements its OBO counter by the number of eligible RA-RUs indicated in the Trigger frame 1, i.e., two RA-RUs for unassociated STAs. As shown in Trigger frame 1, RU4 and RU5 with AID 2045 indicate that these two RUs are for unassociated STAs, i.e., STA 3 in this example. Since STA 3’s OBO counter decrements to a nonzero value, it maintains the new OBO value (2) until it receives a later Trigger frame carrying RA-RUs for unassociated STAs.

After transmission of HE trigger-based (TB) physical layer protocol data unit (PPDU) in response to Trigger frame 1:

● STA 4 has additional frames pending for the AP. Therefore, it maintains its initial OBO value (2) until it receives a later Trigger frame carrying RA-RUs for associated STAs.

● STA 1 has additional frames pending for the AP and randomly selects a new OBO value (4) .

Upon receiving a following trigger frame, i.e., Trigger frame 2:

● STA 1, STA 2 and STA 4 decrement their respective OBO counters by number of eligible RARUs, i.e., two in this case. As shown in Trigger frame 2, RU1 and RU2 with AID 0 indicate that these two RUs are for associated STAs, i.e., STA 1, STA 2 and STA 4. Since STA 2 and STA 4’s OBO counters decrements to 0, they both transmit their pending frames on a randomly selected RU (RU2 in the case of STA 2 and RU1 in the case of STA 4) . If either STAs have additional frames pending for the AP, each would randomly select a new OBO value. Since STA 1’s OBO decrements to a nonzero value, it maintains the new OBO value (2) until it receives a later Trigger frame carrying RA-RUs for associated STAs.

● STA 3 decrements its OBO counter by the number of eligible RA-RUs (two in this case) . As shown in Trigger frame 2, RU3 and RU4 with AID 2045 indicate that these two RUs are for unassociated STAs, i.e., STA 3. Since the STA’s OBO counter decrements to 0, it transmits its pending frame on a randomly selected RU (RU4 in this case) .

Typically, QoS clients that are associated to AP and wish to transmit in UL have several options as follows.

EDCA:

During EDCA, a client contends the medium through a random backoff procedure that starts a backoff timer with a value in the [0, CW] interval. CW has a size between the minimum CW size (CWmin) and the maximum CW size (CWmax) . The CW is advertised by AP per AC. When the backoff timer is expired, the client starts the transmission and waits for an acknowledgment (ACK) . In case of an ACK failure, the CW is increased by 1 (until CWmax is reached) and backoff is re-counted until the successful transmission. However, EDCA has disadvantages of the excessive time it may take a client to win the medium (specifically in congested networks) , and its inefficiency as only one client is entitled to transmit its data in UL.

OFDMA unicast allocations:

When AP gains a transmission opportunity (TXOP) via EDCA procedure, it may allocate RUs for designated clients. Assigning the RUs are done by indicating a client a dedicated AID in the User Field of the preceding trigger frame. This method of UL transmission is efficient as many clients may be granted with RUs, however the AP has no knowledge about the client’s transmission buffer at every moment and thus may not always assign dedicated RUs to the client when needed. In this case, a QoS client will have to wait for its RU allocation though may fail to transmit is low latency data in time.

OFDMA broadcast allocations:

When AP gains a TXOP via EDCA procedure, it may allocate RA-RUs for all clients. As previously discussed, assigning the RA-RUs to associated or unassociated STAs (clients) is done by indicating AID value of 0 or 2045.

RA-RUs with AID Value of 0 allow all associated clients to compete on UL transmission via UORA procedure, all clients randomly select value range 0 to CWO and transmit when their OBOs reach 0. RA-RUs with AID value of 2045 indicate the unassociated clients to contend the RA-RUs in the same manner as described above.

However, OFDMA Broadcast allocations is not selective for a group of clients with different QoS characteristics. Hence, it does not allow to prioritize QoS clients in medium access.

Embodiments of this disclosure thus propose an AP, which is able to provide medium link access privileges for those clients. FIG. 2 shows a first network device 200 according to an embodiment of the disclosure. The first network device 200 may comprise processing circuitry (not shown) configured to perform, conduct or initiate the various operations of the first network device 200 described herein. The processing circuitry may comprise hardware and software. The hardware may comprise analog circuitry or digital circuitry, or both analog and digital circuitry. The digital circuitry may comprise components such as application-specific integrated circuits (ASICs) , field-programmable arrays (FPGAs) , digital signal processors (DSPs) , or multi-purpose processors. The first network device 200 may further comprise memory circuitry, which stores one or more instruction (s) that can be executed by the processor or by the processing circuitry, in particular under control of the software. For instance, the memory circuitry may comprise a non-transitory storage medium storing executable software code which, when executed by the processor or the processing circuitry, causes the various operations of the first network device 200 to be performed. In one embodiment, the processing circuitry comprises one or more processors and a non-transitory memory connected to the one or more processors. The non-transitory memory may carry executable program code which, when executed by the one or more processors, causes the first network device 200 to perform, conduct or initiate the operations or methods described herein.

In particular, the first network device 200 is configured to determine one or more group AIDs 201, 201’, for one or more groups 300, 300’ of

second network devices

301, 302, 301’, 302’. Each group 300 comprises one or more

second network devices

301, 302. Then, the first network device 200 is configured to determine one or more time-frequency resources 202, 202’. Each time-frequency resource 202 is associated with one group AID 201. In particular, each time-frequency resource 202 comprises one or more RUs, and each time-frequency resource 202 is allocated to a group 300 of

second network devices

301, 302 with that group AID 201. The first network device 200 is further configured to send a trigger frame 203 to the one or more groups 300, 300’ of

second network devices

301, 302, 301’, 302’. The trigger frame 203 is indicative of one or more group AIDs 201, 201’, which are assigned to the one or more groups 300, 300’ of the

second network devices

301, 302, 301’, 302’, and the time-frequency resources 202, 202’ associated with the one or more group AIDs 201, 201’.

The first network device 200 herein may be an AP compliant with current IEEE 802.11 standards such as 802.11ax or a future version such as 802.11be. The

second network device

301, 302, 301’ or 302’ may be a STA or a client terminal compliant with current IEEE 802.11 standards such as 802.11ax or a future version such as 802.11be.

Embodiments of this disclosure introduce a dedicated group identifier, particularly the group AID, for grouping a set of clients with special service requirements (e.g., low latency) . Embodiments of this disclosure thus propose an AP, i.e., the first network device 200, which is able to provide medium link access privileges for those clients. In this way, the first network device 200 can schedule UL transmissions in an effective and flexible manner in case of traffic congestion and uncertainty information on client’s buffer status.

In particular, according to embodiments of the disclosure, the first network device 200 may be configured to obtain an association requirement from each

second network device

301, 302, 301’, 302’ of the one or more groups 300, 300’ of

second network devices

301, 302, 301’, 302’.

Optionally, the association requirement may comprise at least one of the following: a QoS requirement, one or more ACs, and/or one or more TSIDs, of the

second network device

301, 302, 301’, 302’. In particular, each AC may comprise one or more TIDs of the

second network device

301, 302, 301’, 302’.

Accordingly, the first network device 200 may be further configured to determine the one or more group AIDs 201, 201’ for the one or more groups 300, 300’ of the

second network devices

301, 302, 301’, 302’ based on the one or more association requirements.

For instance, if the first network device 200 obtains a QoS requirement from each

second network device

301, 302, 301’, 302’, for the second network devices with the same QoS requirement (e.g., the

second network devices

301, 302 shown in FIG. 2) , the same group AID (e.g., group AID 201) will be determined for the

second network devices

301 and 302. In this example, the

second network devices

301 and 302 are grouped into the same group, i.e., the group 300 as shown in FIG. 2.

Similarly, the first network device 200 may obtain one or more ACs and/or one or more TSIDs from each

second network device

301, 302, 301’, 302’. In such case, the first network device 200 may determine the same group AID 201’ for the traffic streams of the second network devices 301’, 302’ (as shown in FIG. 2) with the same AC, and/or with the same TSID.

FIG. 3 shows a second network device 301 according to an embodiment of the disclosure. The second network device 301 shown here may be one of the

second network devices

301, 302, 301’, 302’ as shown in FIG. 2. The second network device 301 may comprise processing circuitry (not shown) configured to perform, conduct or initiate the various operations of the second network device 301 described herein. The processing circuitry may comprise hardware and software. The hardware may comprise analog circuitry or digital circuitry, or both analog and digital circuitry. The digital circuitry may comprise components such as application-specific integrated circuits (ASICs) , field-programmable arrays (FPGAs) , digital signal processors (DSPs) , or multi-purpose processors. The second network device 301 may further comprise memory circuitry, which stores one or more instruction (s) that can be executed by the processor or by the processing circuitry, in particular under control of the software. For instance, the memory circuitry may comprise a non-transitory storage medium storing executable software code which, when executed by the processor or the processing circuitry, causes the various operations of the second network device 301 to be performed. In one embodiment, the processing circuitry comprises one or more processors and a non-transitory memory connected to the one or more processors. The non-transitory memory may carry executable program code which, when executed by the one or more processors, causes the second network device 301 to perform, conduct or initiate the operations or methods described herein.

In particular, the second network device 301 is configured to receive a trigger frame 203 from a first network device 200. The first network device 200 may be the first network device shown in FIG. 2. In particular, the trigger frame 203 is indicative of one or more group AIDs 201, 201’, and one or more time-frequency resources 202, 202’, wherein each time-frequency resource 202 being associated with one group AID 201. The one or more group AIDs 201, 201’ are assigned to one or more groups 300 of

second network devices

301, 302. Each time-frequency resource 202 comprises one or more RUs, wherein each time-frequency resource 202 is allocated to a group 300 of

second network devices

301, 302 with that group AID 201.

Further, the second network device 301 is configured to obtain one or more group AIDs 201 that are assigned to the second network device 301, and one or more time-frequency resources 202 that are allocated to the second network device 301, based on the trigger frame 203. Then, the second network device 301 is further configured to contend the one or more time-frequency resources 202 with one or more other second network devices 302 that are assigned with the same one or more group AIDs 201.

As previously mentioned, the first network device 200 and the second network device 301 herein may respectively be an AP and a STA or a client terminal compliant with current IEEE 802.11 standards such as 802.11ax or a future version such as 802.11be.

In particular, according to embodiments of the disclosure, the second network device 301 may be configured to provide an association requirement to the first network device 200. In particular, the one or more group AIDs 201, 201’ assigned to the

second network devices

301, 302 may be determined based on the association requirement. The association requirement may be the same or similar as described in the previous embodiment.

Optionally, the second network devices 301 may be further configured to provide the QoS requirement of the second network device 301 to the first network device 200. Accordingly, the second network devices 301 may be configured to contend the one or more time-frequency resources 202 with the one or more other second network devices 302 that have the same QoS requirement.

Optionally, the second network devices 301 may be further configured to provide the one or more ACs, and/or the one or more TSIDs from the second network device 301 to the first network device 200. Accordingly, for a particular traffic stream, the second network devices 301 may be configured to contend the one or more time-frequency resources 202 with traffic streams of the one or more other second network devices 302 with the same AC, and/or with the same TSID.

Notably, the second network devices 301 may be further configured to maintain a backoff counter associated with each of the one or more group AIDs 201, wherein each backoff counter is set with an initial value.

According to an embodiment of the disclosure, when a time-frequency resource 202 associated with a particular group AID 201 is obtained, the second network device 301 may be further configured to decrement the backoff counter associated with the group AID 201 by a number of the one or more RUs of the time-frequency resource 202.

When the backoff counter decrements to zero, that is, the second network device 301 is allowed to transmit, the second network device 301 may be further configured to select a RU from the one or more RUs of the time-frequency resource 202, and transmit one or more frames on the selected RU.

After the transmission, the second network device 301 may be further configured to select a new value for the backoff counter.

In the following, two specific embodiments for an AP (i.e., the first network device 200) to allocate OFDMA RA-RUs are described in details.

Allocating Group AID (G-AID) for QoS clients:

Notably, clients associated with AP can be admitted as QoS clients with Low Latency requirement. FIG. 4 depicts an association and admission procedure to allocate dedicated G-AID.

In this embodiment, AP may allocate Client A and Client B a RA-RU link access with G-AID during operation. AP here may be the first network device 200 as shown in FIG. 2 or FIG. 3. Possibly, Client A and Client B may be the

second network devices

301, 302 as shown in FIG. 2 or FIG. 3.

During operation, AP contends the wireless medium and sends a trigger frame with the client respective G-AID in the User Info field. The trigger frame may the trigger frame 203 as shown in FIG. 2 or FIG. 3. The respective G-AID (G-AID = 2040) here may be a group AID 201 as shown in FIG. 2 or FIG. 3. Only clients that were admitted with that G-AID may contend the RA-RU and transmit their low latency data.

In particular, clients with low latency data requirements (Client A and Client B) may inform the AP their QoS requirement during association procedure or via a traffic specification procedure (TSPEC) . In response, AP may group several QoS clients that share common link access characteristics to an assigned dedicated AID (G-AID) . AP may inform the client that they are member of a Group AID value via TSPEC Response or Association Response messages.

AP may advertise the Group AID in the User Info field of the trigger frame that precedes the UL OFDMA transmission. Clients with their G-AID value in the trigger frame may start and transmit in the respective RA-RU during the UORA procedure. In particular, those QoS clients contend transmission in the G-AID related RA-RU only with members of the Group AID and not with all clients. That is, if only Client A and Client B are assigned with the same G-AID, Client A only has to content transmission in the related RA-RU with Client B.

FIG. 5 shows an improved UORA procedure incorporated with G-AID allocation according to an embodiment of the disclosure. Notably, the UORA procedure shown in FIG. 5 is modified based on the UORA procedure shown in FIG. 1. In this example, the AP may allocate RUs to STA 1, STA 2, STA 3, STA 4 and STA 5 (by sending trigger frames) . The AP here may be the first network device 200 as shown in FIG. 2 or FIG. 3, and each of the STAs may be one of the

second network devices

301, 302, 301’, 302’ as shown in FIG. 2 or FIG. 3.

FIG. 5 (a) shows two trigger frames: Trigger frame 1, and Trigger frame 2. Before Trigger frame 1 was sent by the AP, client STA 1, STA 2, STA 3, STA 4 and STA 5 had initial OBO values as shown in Table 1, and FIG. 5 (b) .

Table 1 -Initial AID and G-AID OBO values on Trigger frame 1

It should be noted that this example shows a functionality where each STA manages different OBO counters for different RA-RU categories. Operation with only one OBO counter for all RA-RU is also possible. Further, it is also worth mentioning that RA-RU associated with G-AID can be in any size and length to accommodate client transmission (are not limited in size as depicted in this example)

FIG. 5 (b) shows the procedure upon receiving Trigger frame 1:

● STA 1 is associated with the AP and has pending frames. Since it is allocated with a dedicated RU (i.e., RU1) , hence it does not contend for RA-RUs and transmits its pending frames on RU1.

● STA 2 and STA 3 are registered to a group with G-AID = 2040. Both stations may decrement their OBO counters by the number of eligible RA-RUs indicated in the Trigger frame for only one of the RA-RU type. (i.e., 2 RA-RUs for G-AID = 2040 or 1 RA-RU for AID = 0) . Both STA2 and STA3 contend for the G-AID2040 as they have low latency data for transmission.

● STA 2, STA 3 and STA 4 are associated with the AP, having pending frames for the AP and are eligible to decrement their respective AID0 OBO counters by the number of eligible RA-RUs indicated in Trigger frame 1 (i.e., one RA-RU for associated STAs AID=0) . However, since STA2 and STA3 already decremented their G-AID2040 OBO, they are not permitted to decrement also AID0 OBO on this frame. Thus, only STA4 decrements its AID0 OBO from 3 to 2.

● As STA 3’s G-AID2040 OBO counter decrements to 0, it randomly selects from the eligible set of RA-RUs allocated for G-AID 2040 (i.e., RU2, RU3) and transmits its pending frames on RU2.

● Since STA 2’s and STA 4’s OBO counters decrement to a nonzero value, they maintain their OBO value until they receive a later Trigger frame carrying RA-RUs for associated STAs.

● STA 5 is not associated with the AP but has a pending frame for the AP, hence it decrements its AID2045 OBO counter by the number of eligible RA-RUs indicated in Trigger frame 1 (i.e., one RA-RUs for unassociated STAs) .

After transmission of TB PPDU in response to Trigger frame 1:

● STA 1, STA 2, STA 4 and STA 5 maintain their initial OBO value until they receive a later Trigger frame carrying RA-RUs for associated STAs.

● STA 3 randomly selects a new AID2040 OBO value (4 in this example) .

Table 2 -Initial AID and G-AID OBO values on Trigger frame 2

FIG. 5 (c) shows the procedure upon receiving Trigger frame 2:

● STA 1, and STA 3 decrement their respective AID0 OBO counters by number of eligible RA-RUs (i.e., two RA-RU for associated STAs AID=0) . Since STA2 decrements its G-AID2040 OBO, it is not permitted to contend for the AID0 RA-RU hence does not decrement its AID0 OBO.

● STA 2 decrement its G-AID2040 OBO counters by the number of eligible RA-RUs indicated in Trigger frame 2. (i.e., one RA-RUs) . Since STA 2 G-AID2040 OBO counter decrements to 0, it transmits his pending frames on a randomly selected RU (RU2) . If it has additional frames pending for the AP, it would randomly select a new OBO value.

● Since STA 1’s AID0 OBO counter decrements to a zero value, it transmits its pending frames on RU4 that it randomly selects from the eligible set of RA-RUs allocated for AID0 (i.e., RU3, RU4) .

● STA 4 is allocated with a dedicated RU (RU1) hence it does not contend for RA-RUs and directly transmits its pending frames on RU1.

● STA 5 is not associated with the AP, hence it decrements its AID2045 OBO counter (i.e., one RA-RUs for unassociated STAs) . Since its OBO counter decrements to 0, it transmit its pending frames on RU5.

Allocating G-AID values for different ACs:

As previously discussed, ACs can represent priority levels of different types of traffic in EDCA. In this embodiment, AP may assign specific G-AID values for different ACs (G-AID [AC] ) , and advertise them via Association or Probe Response frames. FIG. 6 depicts an association and admission procedure to allocate dedicated G-AID [AC] . AP here may be the first network device 200 as shown in FIG. 2 or FIG. 3. Possibly, Client A and Client B shown in FIG. 6 may be the second network devices 301’, 302’ as shown in FIG. 2 or FIG. 3.

Generally speaking, AP contends the wireless medium and sends a trigger frame with related G-AID in the User Info field. The trigger frame here may the trigger frame 203 as shown in FIG. 2 or FIG. 3. The respective G-AID (G-AID = 2003) indicated in the trigger frame here may be a group AID 201 as shown in FIG. 2 or FIG. 3. Only clients with traffic associated with that G-AID [AC] may contend the RA-RU and transmit their data. Notably, G-AID can be assigned according to TID as well.

In particular, clients (Client A and Client B) may inform the AP their different ACs and/or one or more TSIDs during association procedure. In response, AP may assign G-AID values for a classified traffic per AC. STAs can transmit only the classified traffic in the respective G-AID [AC] RA-RU. STAs that associate with the AP receive from the AP the mapping of UORA related G-AID values to ACs, for example: AC-BE (best effort) = G-AID2000; AC-BK (background) = G-AID2001; AC-VI (video) = G-AID2002; and AC-VO (voice) = G-AID2003.

According to this embodiment, STAs contend transmission on G-AID only with stations that have the same data with the traffic classification. For instance, in the example shown in FIG. 6, AP allocates a RA-RU for traffic with G-AID2003 (in a trigger frame) . In this case, voice traffic (AC-VO) is assigned with the G-AID2003. Thus, Client A only contends transmission for AC_VO traffic in the related RA-RU with Client B that also have AC_VO traffic to transmit.

FIG. 7 shows an improved UORA procedure incorporated with G-AID [AC] allocation according to an embodiment of the disclosure. Notably, the UORA procedure shown in FIG. 7 is modified based on the UORA procedure shown in FIG. 1. In this example, the AP may allocate RUs to STA 1, STA 2, STA 3, STA 4 and STA 5 (by sending trigger frames) . The AP here may be the first network device 200 as shown in FIG. 2 or FIG. 3, and each of the STAs may be one of the

second network devices

301, 302, 301’, 302’ as shown in FIG. 2 or FIG. 3.

FIG. 7 (a) shows two trigger frames: Trigger frame 1, and Trigger frame 2. Before Trigger frame 1 was sent by the AP, client STA 1, STA 2, STA 3, STA 4 and STA 5 had initial OBO values as shown in Table 3, and FIG. 7 (b) .

Table 3 -Initial G-AID [AC] OBO values on Trigger frame 1

Similar as mentioned in the previous embodiment, although this example shows a functionality where each STA manages different OBO counters for different ACs. Operation with only one OBO counter for all ACs is also possible. Further, RA-RU (s) associated with G-AID [AC] can be in any size and length to accommodate client transmission.

FIG. 7 (b) shows the procedure upon receiving Trigger frame 1:

● STA 1 is allocated with a dedicated RU (RU1) , hence it does not contend for RA-RUs and instead transmits its pending frames on RU1.

● STA 2 and STA 3 decrement their G-AID [AC] OBO counters by the numbers of eligible RA-RUs indicated in Trigger frame 1 (i.e., two RA-RUs for AC_BE, one RA-RU for AC_VI and one RA-RU for AC_VO) .

● STA 4 also decrements its respective G-AID [AC] OBO counters by the numbers of eligible RA-RUs indicated in Trigger frame 1 (i.e., two RA-RUs for AC_BE, one RA-RU for AC_VI and one RA-RU for AC_VO) . As STA 4 AC_BE OBO counter decrements to 0, it transmits its pending AC_BE frames on RU3 for instance. RU3 is randomly selected from the eligible set of RA-RUs allocated for AC_BE (i.e., RU2, RU3) .

● STA 5 also decrements its respective G-AID [AC] OBO counters by the numbers of eligible RA-RUs indicated in Trigger frame 1. As STA 5 AC_VO OBO counter decrements to 0, it transmits its pending AC_VO frames on RU5 that is allocated for AC_VO.

After transmission of TB PPDU in response to Trigger frame 1:

● All STAs maintain their initial OBO value until they receive a later Trigger frame carrying RA-RUs.

● STA 4 randomly select new AC_BE OBO values (5 in this example) .

● STA 5 randomly select new AC_VO OBO values (4 in this example) .

Table 4 -Initial G-AID [AC] OBO values on Trigger frame 2

FIG. 7 (c) shows the procedure upon receiving Trigger frame 2:

● STA 1, STA 2 and STA 5 decrement their G-AID [AC] OBO counters by numbers of eligible RA-RUs (i.e., two RA-RU for AC_BE, one RA-RU for AC_BK and one RA-RU for AC_VO) .

● Since STA 1 and STA 2 AC_BE OBO counters decrements to zero, they randomly selects from the eligible set of RA-RUs allocated for AC_BE (i.e., RU2, RU3) . In this example, both STA 1 and STA 2 pick RU2 hence collision occurs on two transmissions.

● STA 3 was allocated a dedicated RU (RU1) hence it does not contend for RA-RUs and instead transmits its pending frames on RU1.

● STA 4 decrement its G-AID [AC] OBO counters by number of eligible RA-RUs (i.e., two RA-RU for AC_BE, one RA-RU for AC_BK and one RA-RU for AC_VO) . Since AC_BK OBO counter decrements to zero, STA 4 transmits its AC_BK frames on RU 4.

802.11 standards incorporated four different AC buffer queues. Each AC stores traffic data with different QoS characteristics. Table 5 below shows the current standard definition of AC:

ACI	AC	Description
0	AC_BE	Best effort
1	AC_BK	Background
2	AC_VI	Video
3	AC_VO	Voice

Table 5 -Current standard definition for AC

As previously discussed, during EDCA in case of an ACK failure (e.g., due to a collision) , CW will be increased by 1 (until CWmax is reached) and backoff will be re-counted until the successful transmission. In particular, Exponent of CW (ECW, i.e., 2 ^CW) may be used for the backoff algorithm with an initial /minimal (ECWmin) and maximal (ECWmax) values.

In addition to ECWmin/ECWmax values which are assigned for EDCA link access, this disclosure further proposes to add a G-AID per AC for UORA link access, and additionally a minimum value and a maximum value of CWO, i.e., CWOmin and CWOmax, for each AC for UORA link access. The CWOs can be set according to the traffic expected in each AC. For instance, for categories with heavier traffic, a wider window of CWO may be set.

As an AP typically advertises the ECWmin/ECWmax used by the clients for EDCA backoff count, similar values can be used to calculate OBO in different traffic ACs during the UORA link access procedure.

According to embodiments of this disclosure, AP, i.e., the first network device 200 may advertise new additional CWOmin/CWOmax along with existing ECWmin/ECWmax to all clients, i.e., the

second network devices

301, 302, 301’, 302’. In particular, CWOmin/CWOmax will be used by the

second network devices

301, 302, 301’, 302’according to the traffic AC during the UORA link access procedure.

Clients, i.e., the

second network devices

301, 302, 301’, 302’, perform the following modified UORA procedure with value that matches the AC from which the data is transmitted:

UORA random access allocation incorporated with CWOmin/CWOmax is performed as follow:

1. OBOs are set to random value ranged from 0 to CWO. In particular, CWO =aCWOmin [AC] = CWOmin [AC] , as advertised by the first network device 200 for the AC from which the data is transmitted.

2. Each second network device 301 decrements its non-zero OBO value by 1 for every RA-RU assigned for it.

3. The second network device 301 with OBO decremented to 0, randomly selects any one of the assigned RUs for random access and transmits its frame.

4. The second network device 301, which transmitted a frame during RA-RU and did not receive an ACK frame or a response frame (e.g., due to a collision or other) , shall repeat steps 2 -4 with random value range 0 to aCWOmin = Minimum [aCWOmin + 1, ECOmax] , and shall continue until a successful transmission.

According to an embodiment of this disclosure, during Association, the first network device 200 may advertise the following parameters as shown in Table 6:

Table 6 -Allocated different CWOmin/CWOmax per AC

In this embodiment, the first network device 200 contends the medium until transmission opportunity is achieved.

● The first network device 200 sends a trigger frame, e.g., the trigger frame 203 as shown in FIG. 2 or FIG. 3, with G-AID2003 (AC_VO) in the User Info field.

● Client AID1 (e.g., the second network device 301) has pending data in AC_BE, hence OBO is initialized with value 0 to 9 (e.g., 7) .

● Client AID2 (e.g., the second network device 301’) has pending data in AC_VO, hence OBO is initialized with value 0 to 3 (e.g., 1) .

● Client AID3 (e.g., the second network device 302’) has pending data in AC_VO, hence OBO is initialized with value 0 to 3 (e.g., 2) .

● Both clients AID=1 and AID=3 contend the RA-RU, however since client AID3 has traffic associated with higher priority AC, it is capable to transmit its frame earlier to AID.

● In case of a collision between Client AID2 and Client AID3 transmission on G-AID [AC-VO] , both client will randomly select OBO value of CWOmin+1 (i.e. a random value of [0…4] ) .

In can be seen that, different CWOmin/CWOmax are set for different ACs. As shown in Table 6, CWOmin = 3 and CWOmax = 9 is set for traffic AC_VO, while CWOmin = 9 and CWOmax = 15 is set for traffic AC_BE. For instance, OBO associated with traffic AC_VO may be initially with 3 (a value ranged (0, CWOmin] ) , i.e., OBO may be set to 8 (2 ^CWOmin, i.e., 2 ³) . Similarly, OBO associated with traffic AC_BE may be initially with 4 (a value ranged (0, CWOmin] ) , i.e., OBO may be set to 16 (2 ^CWOmin, i.e., 2 ⁴) . That means, voice traffic can be prioritized over best effort traffic.

It should be noted that although in this example, different minimum value and maximum value of CWO are associated with ACs, this method can apply to the embodiments for allocating RA-RUs for QoS clients with low latency requirement as well.

According to an embodiment of this disclosure, each group AID 201 may be further associated with one or more CWs (i.e., CWOs) , wherein the first network device 200 may be further configured to determine a minimum value and a maximum value of each of the one or more CWs. Accordingly, the first network device 200 may be further configured to provide each of the one or more minimum values and the one or more maximum values to the group 300 of

second network devices

301, 302 with the respective associated group AID 201.

The information of which CWOmin/CWOmax is associated with which group AID may be delivered in other frames like (Probe/Association Response) and not must be delivered via a trigger frame. Typically, the trigger frame may be required to be very short. For instance, the second network devices 301, 302 (of the group 300, which is assigned with the group AID 201) may receive all medium access characteristics prior to the trigger frame 203, and receive only the group AID 201 in the trigger frame 203.

Optionally, in response to the association requirement, the first network device 200 may be further configured to send an association response to the

second network device

301, 302, 301’, 302’ that sends the association requirement, wherein the association response is indicative of the values of CWOmin/CWOmax associated with each of the one or more group AIDs 201, 201’.

Accordingly, the second network devices 301 may be configured to set an initial value of a backoff counter associated with a particular group AID 201 to a value range from 0 to two of the power of the minimum value of the CW associated with the group AID 201, i.e., 2 ^CWOmin.

Further, when a collision happens, the second network devices 301 may be configured to select a new value range from 0 to 2 ^CWOmin+1, for the backoff counter.

For instance, if CWOmin = 3 and CWOmax = 9 associated with the group AID 201 are set for the second network devices 301, its OBO associated with the group AID 201 may be initialized with a value from (0, 2 ³] , i.e., (0, 8] . In case of a collision, the OBO will be selected from the new range (0, 2 ⁴] , i.e., (0, 16] .

To summarize, embodiments of this disclosure enable grouping STAs that support a large BW into one or more MU-MIMO allocations. If a single MU-MIMO allocation is defined over the entire BW, the solution may be similar to 801.11ax full BW compression mode, with extra addressing parking mechanism for the STAs. If two MU-MIMO allocations are defined, the first MU-MIMO allocation may span P160, while the second MU-MIMO allocation spans S80/S160 (for BW=240/320MHz) . According to embodiments proposed in this disclosure, subfields for resource allocation can be omitted, thereby minimizing a size of the EHT-SIG common field.

In addition, this disclosure also proposes to move SC field to common fields of the U-SIG/EHT-SIG. Notably, there may be 1 or 2 SC fields for STAs (for 1 or 2 groups) . Since all STAs are related to one of the SC fields, it may be a waste to repeat them in all user-fields. Thus, it may be desired to put the SC fields in the common field. Further, this disclosure also supports to leave the SC fields in the user-fields as used in 802.11ax, to preserve 802.11ax full BW compression mode.

FIG. 8 shows a method 800 according to an embodiment of the disclosure. In a particular embodiment of the disclosure, the method 800 is performed by a first network device 200 shown in FIG. 2 or FIG. 3. The method 800 comprises: a step 801 of determining one or more group AIDs 201, 201’, for one or more groups 300, 300’ of

second network devices

301, 302, 301’, 302’. In particular, each group 300 comprising one or more

second network devices

301, 302. The method 800 further comprises a step 802 of determining one or more time-frequency resources 202, 202’, and each time-frequency resource 202 being associated with one group AID 201. In particular, each time-frequency resource 202 comprises one or more RUs, and wherein each time-frequency resource 202 is allocated to a group 300 of

second network devices

301, 302 with that group AID 201. The method 800 further comprises a step 803 of sending a trigger frame 203 to the one or more groups 300, 300’ of

second network devices

301, 302, 301’, 302’. In particular, the trigger frame 203 is indicative of one or more group AIDs 201, 201’, which are assigned to the one or more groups 300, 300’ of the

second network devices

301, 302, 301’, 302’, and the time-frequency resources 202, 202’ associated with the one or more group AIDs 201, 201’. Possibly, each of the

second network devices

301, 302, 301’, 302’ may be the second network device 301 shown in FIG. 3.

FIG. 9 shows a method 900 according to an embodiment of the disclosure. In a particular embodiment of the disclosure, the method 900 is performed by a second network device 301 shown in FIG. 3. The method 900 comprises: a step 901 of receiving a trigger frame 203 from a first network device 200, wherein the trigger frame 203 is indicative of one or more group AIDs 201, 201’, which are assigned to one or more groups 300 of

second network devices

301, 302, and one or more time-frequency resources 202, 202’, each time-frequency resource 202 being associated with one group AID 201. In particular, each time-frequency resource 202 is allocated to a group 300 of

second network devices

301, 302 with that group AID 201, wherein each time-frequency resource comprises one or more RUs. The method 900 further comprises a step 902 of obtaining one or more group AIDs 201 that are assigned to the second network device 302, and one or more time-frequency resources 202 that are allocated to the second network device 301, based on the trigger frame 203. The method 900 further comprises a step 903 of contending the one or more time-frequency resources 202 with one or more other second network devices 302 that are assigned with the same one or more group AIDs 201. Possibly, the first network device 200 is the first network device shown in FIG. 2 or FIG. 3.

The present disclosure has been described in conjunction with various embodiments as examples as well as implementations. However, other variations can be understood and effected by those persons skilled in the art and practicing the claimed disclosure, from the studies of the drawings, this disclosure and the independent claims. In the claims as well as in the description the word “comprising” does not exclude other elements or steps and the indefinite article “a” or “an” does not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in the mutual different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous implementation.

Furthermore, any method according to embodiments of the disclosure may be implemented in a computer program, having code means, which when run by processing means causes the processing means to execute the steps of the method. The computer program is included in a computer readable medium of a computer program product. The computer readable medium may comprise essentially any memory, such as a ROM (Read-Only Memory) , a PROM (Programmable Read-Only Memory) , an EPROM (Erasable PROM) , a Flash memory, an EEPROM (Electrically Erasable PROM) , or a hard disk drive.

Moreover, it is realized by the skilled person that embodiments of the first network device 200 and the second network device 301, respectively, comprises the necessary communication capabilities in the form of e.g., functions, means, units, elements, etc., for performing the solution. Examples of other such means, units, elements and functions are: processors, memory, buffers, control logic, encoders, decoders, rate matchers, de-rate matchers, mapping units, multipliers, decision units, selecting units, switches, interleavers, de-interleavers, modulators, demodulators, inputs, outputs, antennas, amplifiers, receiver units, transmitter units, DSPs, trellis-coded modulation (TCM) encoder, TCM decoder, power supply units, power feeders, communication interfaces, communication protocols, etc. which are suitably arranged together for performing the solution.

Especially, the processor (s) of the first network device 200 and the second network device 301, respectively, may comprise, e.g., one or more instances of a Central Processing Unit (CPU) , a processing unit, a processing circuit, a processor, an Application Specific Integrated Circuit (ASIC) , a microprocessor, or other processing logic that may interpret and execute instructions. The expression “processor” may thus represent a processing circuitry comprising a plurality of processing circuits, such as, e.g., any, some or all of the ones mentioned above. The processing circuitry may further perform data processing functions for inputting, outputting, and processing of data comprising data buffering and device control functions, such as call processing control, user interface control, or the like.

Claims

A first network device (200) , configured to:

determine one or more group association identifiers, AIDs (201, 201’) , for one or more groups (300, 300’) of second network devices (301, 302, 301’, 302’) , each group (300) comprising one or more second network devices (301, 302) ;

determine one or more time-frequency resources (202, 202’) , each time-frequency resource (202) being associated with one group AID (201) , wherein each time-frequency resource (202) comprises one or more resource units, and wherein each time-frequency resource (202) is allocated to a group (300) of second network devices (301, 302) with that group AID (201) ; and

send a trigger frame (203) to the one or more groups (300, 300’) of second network devices (301, 302, 301’, 302’) , wherein the trigger frame (203) is indicative of one or more group AIDs (201, 201’) , which are assigned to the one or more groups (300, 300’) of the second network devices (301, 302, 301’, 302’) , and the time-frequency resources (202, 202’) associated with the one or more group AIDs (201, 201’) .
The first network device (200) according to claim 1, further configured to:

obtain an association requirement from each second network device (301, 302, 301’, 302’) of the one or more groups (300, 300’) of second network devices (301, 302, 301’, 302’) ; and

determine the one or more group AIDs (201, 201’) for the one or more groups (300, 300’) of the second network devices (301, 302, 301’, 302’) based on the one or more association requirements.
The first network device (200) according to claim 1 or 2, wherein the association requirement comprises:

- a quality of service, QoS, requirement, of the second network device (301, 302, 301’, 302’) ;

- one or more access categories, ACs, each comprising one or more traffic identifiers, TIDs, of the second network device (301, 302, 301’, 302’) ; and/or

- one or more traffic stream identifiers, TSIDs, of the second network device (301, 302, 301’, 302’) .
The first network device (200) according to claim 3, further configured to:

obtain a QoS requirement from each second network device (301, 302, 301’, 302’) of the one or more groups (300, 300’) of second network devices (301, 302, 301’, 302’) ; and

determine the same group AID (201) for the second network devices (301, 302) with the same QoS requirement.
The first network device (200) according to claim 3 or 4, further configured to:

obtain one or more ACs and/or one or more TSIDs from each second network device (301, 302, 301’, 302’) of the one or more groups (300, 300’) of the second network devices (301, 302, 301’, 302’) ; and

determine the same group AID (201’) for the traffic streams of the second network devices (301’, 302’) of the one or more groups (300’) of the second network devices (301, 302, 301’, 302’) with the same AC, and/or with the same TSID.
The first network device (200) according to one of the claims 1 to 5, wherein each group AID (201) is further associated with one or more contention windows, wherein the first network device (200) is further configured to:

determine a minimum value and a maximum value of each of the one or more contention windows; and

provide each of the one or more minimum values and the one or more maximum values to the group (300) of second network devices (301, 302) with the respective associated group AID (201) .
The first network device (200) according to claims 2 and 6, further configured to:

in response to the association requirement, send an association response to the second network device (301, 302, 301’, 302’) that sends the association requirement, wherein the association response is indicative of the minimum value and the maximum value of the contention window associated with each of the one or more group AIDs (201, 201’) .
A second network device (301) , configured to:

receive a trigger frame (203) from a first network device (200) , wherein the trigger frame (203) is indicative of one or more group association identifiers, AIDs (201, 201’) , which are assigned to one or more groups (300) of second network devices (301, 302) , and one or more time-frequency resources (202, 202’) , each time-frequency resource (202) being associated with one group AID (201) , wherein each time-frequency resource (202) comprises one or more resource units, wherein each time-frequency resource (202) is allocated to a group (300) of second network devices (301, 302) with that group AID (201) ;

obtain one or more group AIDs (201) that are assigned to the second network device (301) , and one or more time-frequency resources (202) that are allocated to the second network device (301) , based on the trigger frame (203) ; and

contend the one or more time-frequency resources (202) with one or more other second network devices (302) that are assigned with the same one or more group AIDs (201) .
The second network device (301) according to claim 8, further configured to:

provide an association requirement to the first network device (200) ;

wherein the one or more group AIDs (201, 201’) assigned to the second network devices (301, 302) are determined based on the association requirement.
The second network device (301) according to claim 8 or 9, wherein the association requirement comprises:

- a quality of service, QoS, requirement, of the second network device (301) ;

- one or more access categories, ACs, each comprising one or more traffic identifiers, TIDs, of the second network device (301) ; and/or

- one or more traffic stream identifiers, TSIDs, of the second network device (301) .
The second network device (301) according to claim 10, further configured to:

provide the QoS requirement of the second network device (301) to the first network device (200) ; and

contend the one or more time-frequency resources (202) with the one or more other second network devices (302) that have the same QoS requirement.
The second network device (301) according to claim 10 or 11, further configured to:

provide the one or more ACs, and/or the one or more TSIDs from the second network device (301) to the first network device (200) ; and

for a particular traffic stream of the second network device (301) , contend the one or more time-frequency resources (202) with traffic streams of the one or more other second network devices (302) with the same AC, and/or with the same TSID.
The second network device (301) according to one of the claims 8 to 12, further configured to:

maintain a backoff counter associated with each of the one or more group AIDs (201) , wherein each backoff counter is set with an initial value.
The second network device (301) according to claim 13, when a time-frequency resource (202) associated with a particular group AID (201) is obtained, the second network device (301) is further configured to:

decrement the backoff counter associated with the group AID (201) by a number of the one or more resource units of the time-frequency resource (202) .
The second network device (301) according to claim 14, further configured to:

select a resource unit from the one or more resource units of the time-frequency resource (202) , when the backoff counter decrements to zero; and

transmit one or more frames on the selected resource unit.
The second network device (301) according to claim 15, further configured to:

select a new value for the backoff counter after transmitting the one or more frames.
The second network device (301) according to one of the claims 8 to 16, further configured to:

obtain a minimum value and a maximum value of a contention window associated with each of the one or more group AIDs (201) , to the second network device (301) .
The second network device (301) according to claims 9 and 17, further configured to:

receive an association response from the first network device (200) , wherein the association response is indicative of the minimum value and the maximum value of the contention window associated with each of the one or more group AIDs (201) .
The second network device (301) according to claim 13, and claims 17 or 18, further configured to:

set an initial value of a backoff counter associated with a particular group AID (201) to a value range from 0 to two of the power of the minimum value of the contention window associated with the group AID (201) .
The second network device (301) according to claim 19, further configured to:

select a new value range from 0 to two of the power of the minimum value of the contention window plus one, for the backoff counter, when a collision happens.
A method (800) performed by a first network device (200) , the method comprising:

determining (801) one or more group association identifiers, AIDs (201, 201’) , for one or more groups (300, 300’) of second network devices (301, 302, 301’, 302’) , each group (300) comprising one or more second network devices (301, 302) ;

determining (802) one or more time-frequency resources (202, 202’) , each time-frequency resource (202) being associated with one group AID (201) , wherein each time-frequency resource (202) comprises one or more resource units, and wherein each time-frequency resource (202) is allocated to a group (300) of second network devices (301, 302) with that group AID (201) ; and

sending (803) a trigger frame (203) to the one or more groups (300, 300’) of second network devices (301, 302, 301’, 302’) , wherein the trigger frame (203) is indicative of one or more group AIDs (201, 201’) , which are assigned to the one or more groups (300, 300’) of the second network devices (301, 302, 301’, 302’) , and the time-frequency resources (202, 202’) associated with the one or more group AIDs (201, 201’) .
A method (900) performed by a second network device (301) , the method (1000) comprising:

receiving (901) a trigger frame (203) from a first network device (200) , wherein the trigger frame (203) is indicative of one or more group association identifiers, AIDs (201, 201’) , which are assigned to one or more groups (300) of second network devices (301, 302) , and one or more time-frequency resources (202, 202’) , each time-frequency resource (202) being associated with one group AID (201) , wherein each time-frequency resource (202) is allocated to a group (300) of second network devices (301, 302) with that group AID (201) , wherein each time-frequency resource comprises one or more resource units;

obtaining (902) one or more group AIDs (201) that are assigned to the second network device (302) , and one or more time-frequency resources (202) that are allocated to the second network device (301) , based on the trigger frame (203) ; and

contending (903) the one or more time-frequency resources (202) with one or more other second network devices (302) that are assigned with the same one or more group AIDs (201) .
A computer program comprising a program code for performing, when running on a computer, the method (800, 900) according to claim 21 or 22.