CN111512581B - Apparatus and method for NDP feedback - Google Patents

Abstract

The present invention provides an apparatus 100, the apparatus 100 being configured to transmit a trigger message 101 on a plurality of channels 102 within a determined bandwidth. Thus, the trigger message 101 indicates 103 a primary channel 104 of the plurality of channels 102. The present invention also provides an apparatus 200, the apparatus 200 configured to receive a trigger message 101 on one of a plurality of channels 102 within a determined bandwidth, and determine a primary channel 104 of the plurality of channels 102 based on the received trigger message 101. The invention also provides corresponding methods 400 and 500, respectively, and a data structure of a trigger message 101, the data structure comprising information 103, the information 103 indicating a primary channel 104 of a plurality of channels 200 within a determined bandwidth.

Description

Apparatus and method for NDP feedback

Technical Field

The present invention relates to a device for transmitting a trigger message, for example, an Access Point (AP) for transmitting a Null Data Packet (NDP) trigger frame. Furthermore, the present invention relates to an apparatus, such as a Station (STA), for receiving such a trigger message and responding based on the received trigger message. Thus, the two devices described above can implement the NDP feedback mechanism. The invention also relates to a corresponding method for sending and receiving trigger messages.

Background

An NDP feedback (reporting) mechanism is defined in P802.11 draft 2.0, which allows a device such as an AP to trigger and collect short feedback from multiple other devices such as high-efficiency (HE) STAs. The NDP feedback mechanism allows a relatively large number of STAs to respond to a trigger frame sent by the AP using only a single bit to indicate that they need Uplink (UL) resources. Feedback (e.g., resource requests) in response to the trigger frame is typically sent within the NDP feedback frame. The NDP feedback mechanism is more efficient than, for example, a HE trigger-based PPDU (HE triggered-based PPDU), in which an AP triggers each of a plurality of STAs to individually transmit data in an uplink according to the HE trigger-based PPDU.

Currently, the NDP feedback mechanism is used only by associated STAs (i.e., associated with the AP) to request uplink resources. The amount of NDP feedback resources available in the frame depends on the bandwidth and is based on the "multiplex flag" field. For example, there are 18 or 36 resources for a 20MHz bandwidth, 36 or 72 resources for a 40MHz bandwidth, and so on.

The trigger frame may specifically be an NDP feedback report poll, which should be sent in the same channel (in downlink) as the NDP feedback (uplink) is requested. The trigger frame is typically sent in "legacy duplication mode", meaning that the NDP feedback report poll will be duplicated on every 20MHz for bandwidths wider than 20 MHz.

The user information field in the above-described NDP feedback report poll (the same as that present in the current version of the 11ax standard) is shown in fig. 7 (a). As shown, there are currently 9+7 reserved bits in the NDP feedback report poll. The values supported by the "feedback type" subfield (used today) are shown in fig. 7 (B). That is, only resource requests are currently possible for associated STAs.

Furthermore, the 802.11 standard defines a so-called "active scanning" procedure according to which a non-associated STA can transmit a probe response request frame, which can be responded to by an AP operating on the same channel (typically 20MHz) through a probe response frame. The probe response frame is typically transmitted by the AP in the legacy (20MHz) mode and is therefore only available to STAs operating in the same channel as the AP. In addition, the reception (destination) address of the probe response frame is generally the address of the requesting STA.

In High Density (HD) environments (e.g., halls, stadiums, etc.), the network overhead generated by such network discovery procedures performed by non-associated STAs may be significant. STAs using the above-described active scanning procedure transmit probe response request frames at least twice on each channel in which each AP operating expects to respond to each received probe response request by a probe response frame. It is therefore desirable to reduce the amount of time currently occupied by probe response request and response messages.

The conventional NDP feedback mechanism does not indicate the location of the primary 20MHz channel or the location of the secondary 20/40/80MHz channel, for example, within the NDP trigger frame.

Therefore, the conventional NDP feedback mechanism has the following problems related to non-associated STAs: the NDP trigger frame may be sent (replicated) on multiple 20MHz channels, so in principle non-associated STAs can decode the NDP trigger frame on any 20MHz channel they are listening to (even if it is not the primary channel). However, the STA cannot know whether a specific 20MHz channel is a primary channel or a secondary channel. Therefore, a non-associated STA that will respond on the channel it is listening to also expects a response on the same channel. Unfortunately, the AP typically desires to send responses to unassociated STAs only on the primary 20MHz channel to limit the number of responses on the other channels and reduce the collision probability. Therefore, a non-associated STA that does not just communicate on the primary channel of the AP cannot receive the response of the AP.

For unassociated STAs, one conventional mechanism that may also be considered is to assign them a temporary Association ID (AID) until the association procedure is completed and they obtain a "fixed" AID. According to this mechanism, NDP feedback resources (and the concatenation of these resources with the temporary AID numbers) are numbered from top to bottom (or bottom to top) of all resources. However, the primary channel may be located anywhere in a set of 20MHz channels (not necessarily on top). However, there is a problem in that non-associated STAs cannot calculate the resources/temporary AIDs allocated to them because they do not know the locations of the primary/secondary channels. For example, the AP may use a 40MHz bandwidth with the primary 20MHz channel at the bottom and the secondary 20MHz channel at the top, in which case the temporary AID number for the primary channel would be the opposite of when the primary channel was at the top of the secondary 20MHz channel.

Disclosure of Invention

In view of the above problems and disadvantages, the present invention is directed to improvements over conventional mechanisms. It is therefore an object of the present invention to provide an apparatus that enables an improved NDP feedback mechanism and an improved probe response request and probe response procedure. In particular, probe response requests and any feedback from non-associated devices should be supported regardless of the total bandwidth, and regardless of whether the non-associated devices are currently in a primary channel or a non-primary channel within the total bandwidth.

The object of the invention is achieved by the solution presented in the attached independent claims. Advantageous embodiments of the invention are further defined in the dependent claims.

In particular, to improve the NDP feedback mechanism, the present invention proposes a device (e.g. an AP) that indicates the location of the primary channel, and preferably also the secondary channel, to other devices (e.g. STAs) via an NDP trigger. Further, to improve the probe response request and probe response procedure, the present invention allows other devices (e.g., STAs) to send probe response requests or any other unassociated resource requests via the NDP feedback mechanism. That is, NDP feedback is advantageously enhanced to support probe response requests.

A first aspect of the present invention provides an apparatus for transmitting a trigger message on a plurality of channels within a determined bandwidth, wherein the trigger message indicates a primary channel of the plurality of channels.

In other words, the trigger message includes information, e.g., a plurality of bits, identifying the primary channel. The apparatus of the first aspect may accordingly implement this information in the data structure of the trigger frame. The apparatus of the first aspect is preferably an AP. It is apparent that the determined bandwidth may include a plurality of channels having a predetermined bandwidth, the plurality of channels having one primary channel and at least one secondary channel. Any device (preferably, STA) that receives the trigger frame may determine the primary channel from this information. Advantageously, the receiving device may in turn decide to switch to the primary channel in order to receive messages from the device of the first aspect, which messages are transmitted only on the primary channel. For example, even if the receiving apparatus is not associated with the apparatus of the first aspect, it may perform a probe response request and probe response procedure since the receiving apparatus knows the primary channel.

In particular, the trigger message may be an NDP trigger frame sent by the AP from which the non-associated STAs that determine the primary channel may send NDP feedback to the AP, which may include a probe response request. The non-associated STA may then receive a subsequent probe response on the primary channel. This is independent of the channel on which the non-associated STA is currently communicating. Because in this case the probe response request and probe response procedure is included in the NDP feedback mechanism, the probe response requests and probe responses sent in the conventional network discovery procedure are significantly reduced (thereby reducing channel usage) and also the collision probability is reduced. Furthermore, NDP feedback resources are more efficiently utilized.

In one implementation form of the first aspect, the trigger message further indicates whether at least one resource is allocated for the probe response request within the plurality of channels.

In another implementation form of the first aspect, the trigger message further indicates an amount of resources allocated for the probe response request within the plurality of channels.

In another implementation form of the first aspect, the above-mentioned number of resources allocated for the probe response request is only on the primary channel, or at the end of the determined bandwidth, or on each of the plurality of channels.

In other words, the trigger message may include information (e.g., a number of bits) identifying the resource and/or the number of resources. The apparatus of the first aspect may accordingly implement this information in the data structure of the trigger frame. This information optimizes the implementation of the probe response request and probe response procedures in the NDP feedback mechanism. The device receiving the trigger message knows when to include the probe response request in its feedback. Furthermore, the devices know how much resources are available. Therefore, the probe response request and the probe response procedure can be efficiently implemented.

In another implementation form of the first aspect, the trigger message further indicates a position of at least one secondary channel of the plurality of channels with respect to the primary channel.

That is, the trigger message may include information (e.g., a plurality of bits) identifying the secondary channel or channels. The apparatus of the first aspect may accordingly implement this information in the data structure of the trigger frame. This information may be used by a receiving device, such as a STA, to calculate the resources/temporary AIDs allocated thereto.

In another implementation form of the first aspect, the trigger message is an NDP feedback report poll, the NDP feedback report poll including a user information field indicating at least the primary channel.

Thus, a solution tailored to the NDP feedback mechanism is provided that allows non-associated receiving devices to use probe response requests in NDP feedback and listen for probe responses on the primary channel.

In another implementation form of the first aspect, 8 bits in the user information field indicate a primary channel, 1 or 2 bits in the user information field indicate a number of resources allocated for a probe response request, 2 to 6 bits in the user information field indicate a location of the at least one secondary channel, and 2 bits in the user information field optionally indicate a determined bandwidth.

Such a user information field provides a specific and advantageous implementation of an NDP trigger frame.

A second aspect of the present invention provides an apparatus for receiving a trigger message on one of a plurality of channels within a determined bandwidth and determining a primary channel of the plurality of channels based on the received trigger message.

That is, the apparatus of the second aspect may extract information relating to the primary channel in the trigger message and may therefore identify the primary channel. The device may then decide to switch to the primary channel for further communication. For example, if the apparatus is an unassociated STA that receives a trigger frame from an AP, the apparatus may feed back a probe response request and may then wait for a probe response on the primary channel. Thus, even if the apparatus of the second aspect is not currently on the primary channel of the AP, the apparatus may participate in a probe response request and probe response procedure, e.g., implemented in an NDP feedback mechanism.

In an implementation form of the second aspect, the apparatus is further configured to determine, according to the received trigger message, the number and/or location of resources allocated for the probe response request within the plurality of channels.

That is, the apparatus of the second aspect may extract information related to the resource in the trigger message. The device thus knows whether it can send a probe response request or other type of unassociated feedback, and on which resource it can send a probe response request or other type of unassociated feedback.

In another implementation form of the second aspect, the apparatus is further configured to determine a position of at least one secondary channel of the plurality of channels relative to the primary channel according to the received trigger message.

That is, the apparatus of the second aspect may extract information related to the secondary channel in the trigger message. The apparatus may then calculate the resources or temporary AIDs allocated thereto.

In another implementation form of the second aspect, the apparatus is further configured to receive a trigger message on a secondary channel of the multiple channels, switch to a primary channel determined according to the trigger message, and send a feedback message on the primary channel, where the feedback message is preferably NDP feedback.

In this way, the apparatus of the second aspect may participate in the probe response request and probe response procedure via NDP feedback or other types of unassociated feedback and responses, regardless of which channel is currently located.

In another implementation form of the second aspect, the apparatus is further configured to send the feedback message on the secondary channel on which the trigger message is received.

This means that the device can send NDP feedback on the secondary channel it is on or on the primary channel it is switching to. If the device wants to receive a probe response, it preferably switches to the primary channel at least.

A third aspect of the invention provides a system comprising an apparatus according to the first aspect or any implementation form of the first aspect, and at least one apparatus according to the second aspect or any implementation form of the second aspect.

The system thus enjoys the above-described advantages and effects of the devices of the first and second aspects.

A fourth aspect of the invention provides a method comprising: and sending a trigger message on a plurality of channels within the determined bandwidth, wherein the trigger message indicates a primary channel in the plurality of channels.

In an implementation form of the fourth aspect, the trigger message further indicates whether at least one resource is allocated for the probe response request within the plurality of channels.

In another implementation form of the fourth aspect, the trigger message further indicates an amount of resources allocated for the probe response request within the plurality of channels.

In another implementation form of the fourth aspect, the number of resources allocated for the probe response request is only on the primary channel, or at the end of the determined bandwidth, or on each of the plurality of channels.

In another implementation form of the fourth aspect, the trigger message further indicates a position of at least one secondary channel in the plurality of channels relative to the primary channel.

In another implementation form of the fourth aspect, the trigger message is an NDP feedback report poll comprising a user information field indicating at least the primary channel.

In another implementation form of the fourth aspect, 8 bits in the user information field indicate the primary channel, 1 or 2 bits in the user information field indicate the amount of resources allocated for the probe response request, 2 bits in the user information field indicate the location of the at least one secondary channel, and 2 bits in the user information field optionally indicate the determined bandwidth.

The method of the fourth aspect provides the same advantages and effects as the device of the first aspect.

A fifth aspect of the present invention provides a method comprising receiving a trigger message on one of a plurality of channels within a determined bandwidth, and determining a primary channel of the plurality of channels based on the received trigger message.

In an implementation form of the fifth aspect, the method comprises: and determining the quantity and/or the position of the resources allocated for the probe response request in the plurality of channels according to the received trigger message.

In another implementation form of the fifth aspect, the method further includes determining a position of at least one secondary channel of the plurality of channels relative to the primary channel according to the received trigger message.

In another implementation form of the fifth aspect, the method further includes receiving a trigger message on a secondary channel of the plurality of channels, switching to a primary channel determined according to the trigger message, and sending a feedback message on the primary channel, preferably, the feedback message is NDP feedback.

In another implementation form of the fifth aspect, the method further includes sending a feedback message on the secondary channel on which the trigger message was received.

The method of the fifth aspect provides the same advantages and effects as the apparatus of the second aspect.

A sixth aspect of the present invention provides a computer-implemented data structure embodied in a medium, wherein the data structure is for a trigger message of an NDP and includes information indicating a primary channel of a plurality of channels within a bandwidth.

In one implementation form of the sixth aspect, the data structure of the trigger message further includes information indicating whether at least one resource is allocated for the probe response request in the plurality of channels.

In another implementation form of the sixth aspect, the data structure of the trigger message further includes information indicating an amount of resources allocated for probe response requests within the plurality of channels.

In another implementation form of the sixth aspect, the number of resources allocated for the probe response request is only on the primary channel, or at the end of the determined bandwidth, or on each of the plurality of channels.

In another implementation form of the sixth aspect, the data structure of the trigger message further includes information indicating a position of at least one secondary channel of the plurality of channels relative to the primary channel.

In another implementation form of the sixth aspect, the data structure of the trigger message is a data structure of an NDP feedback report poll, the NDP feedback report poll comprising a user information field indicating at least the primary channel.

In another implementation form of the sixth aspect, 8 bits in the user information field indicate the primary channel, 1 or 2 bits in the user information field indicate the amount of resources allocated for the probe response request, 2 bits in the user information field indicate the location of the at least one secondary channel, and 2 bits in the user information field optionally indicate the determined bandwidth.

The data structure of the sixth aspect allows advantages and effects of the apparatuses of the first and second aspects to be achieved, respectively.

It should be noted that all the means, elements, units and devices described in the present application may be implemented in software or hardware elements or any combination thereof. All steps performed by the various entities described in this application, as well as the functions described as being performed by the various entities, are intended to mean that the respective entities are adapted or configured to perform the respective steps and functions. In the following description of specific embodiments, even if a specific function or step performed by an external entity is not reflected in the description of a specific element of the entity performing the specific step or function, it should be clear to a person skilled in the art that these methods and functions may be implemented in corresponding software or hardware elements or any combination thereof.

Drawings

The above aspects and implementations of the invention will be explained in the following description of specific embodiments with reference to the drawings, in which:

FIG. 1 shows an apparatus according to an embodiment of the invention;

FIG. 2 shows an apparatus according to an embodiment of the invention;

fig. 3 shows in (a), (B), (C) three examples of data structures (in particular examples of user information fields) of a trigger message according to an embodiment of the invention;

FIG. 4 shows in (A) - (D) four possible message sequences in a system according to an embodiment of the invention;

FIG. 5 illustrates a method according to an embodiment of the invention;

FIG. 6 illustrates a method according to an embodiment of the invention;

fig. 7 illustrates a conventional data structure of a trigger message, and particularly, a user information field of an NDP feedback report poll is shown in (a), and a value of a "feedback type" subfield of the user information field of (a) is shown in (B).

Detailed Description

Fig. 1 shows an apparatus 100 according to an embodiment of the invention. Preferably, the apparatus 100 is an AP. The apparatus 100 is configured to transmit a trigger message 101 on a plurality of channels 102 within a determined bandwidth. Preferably, the trigger message is an NDP trigger frame. The trigger message 101 indicates (e.g., via included information 103) a primary channel 104 of the plurality of channels 102. In the figure, channels 102 are marked with PCh (primary channel 104) and SCh (secondary channel), respectively. Preferably, the predetermined bandwidth of all channels is smaller than the determined bandwidth.

Fig. 2 shows another apparatus 200 according to an embodiment of the invention. Preferably, the apparatus 200 is a STA. The apparatus 200 is configured to receive a trigger message 101 on one of a plurality of channels 102 within a determined bandwidth. Preferably, the trigger message is an NDP trigger frame. The apparatus 200 is further configured to determine a primary channel 104 of the plurality of channels 102 based on the received trigger message 101 (e.g., based on the information 103 included in the trigger message 101). Similarly, channel 102 is labeled with PCh (primary channel 104) and SCh (secondary channel), respectively.

Preferably, the apparatus 100 of fig. 1 and the apparatus 200 of fig. 2 may constitute a system. That is, the trigger message 101 sent by the device 100 of fig. 1 is the trigger message 101 received by the device 200 of fig. 2. The apparatus 200 may extract the information 103 related to the primary channel 104 from the trigger message 101, wherein the information 103 may be included in advance by the apparatus 100. The apparatus 200 may then determine from this information 103 which of the channels 102 is the primary channel 104. Thus, it may decide to switch to the primary channel 104.

As previously mentioned, the trigger message 101 is preferably an NDP trigger frame, such as an NDP feedback report poll, which preferably includes a data structure, such as a user information field 300 (the details of which will be explained below with reference to fig. 3), the user information field 300 indicating 103 at least the primary channel 104. Accordingly, the NDP feedback mechanism may be advantageously implemented in the system (i.e., between the device 100 and the device 200). The device 200 may feed back the NDP trigger frame 101. Since the device 200 is aware of the primary channel 104, it may feed back with a probe response request and may receive a probe response from the device 100 after switching to the primary channel 104.

In a similar manner, the apparatus 100 may include (details of which will also be explained below with reference to fig. 3) information 301, and/or information 302, and/or information 303 in the trigger message 101, the information 301 relating to allocation of resources for probe response requests among the plurality of channels 102, the information 302 relating to a position of one or more secondary channels 401 (details of which will be explained below with reference to fig. 4) among the plurality of channels 102 with respect to the primary channel 104, and the information 303 relating to a determined bandwidth (i.e., a total bandwidth used). Accordingly, the apparatus 200 is configured to extract information 301, 302, and/or 303 from the trigger message 101 and to determine an allocation of resources for the probe response request in the plurality of channels 102, and/or a position of one or more secondary channels 401 in the plurality of channels 102 with respect to the primary channel 104, and/or a determined bandwidth, respectively.

In other words, the apparatus 100 may also be used to indicate the location of the primary channel 104 and optionally the location of the one or more secondary channels 401 to one or more apparatuses 200. Additionally, the apparatus 100 may be used to indicate the number and location of resources allocated for a probe response request, for example, allowing a group of (non-associated) apparatuses 200 to send a probe response request or any other non-associated resource request via NDP feedback (NDP response). The apparatus 100 may thus respond to the set of apparatuses 200, e.g. with a single probe response message or frame, e.g. on the main channel 104, e.g. using a broadcast Receiver Address (RA). A device 200 that is aware of the primary channel 104 may switch to the primary channel 104 to receive the probe response and associate with the device 100. If any of the non-associated device 200's requests are not probe response requests but resource requests, the device 100 may respond by allocating resources.

Fig. 3 shows examples (a), (B), (C) of data structures 300 of trigger messages 101 according to an embodiment of the invention, as a preferred example, in particular the user information field 300 of the trigger message 101, in particular an NDP trigger such as a feedback report poll. Three examples of (a), (B), and (C) will be described in detail below.

In each of (a), (B), (C) examples, the user information field 300 includes (as opposed to the legacy user information field shown in fig. 7 (B)) information (bits) 103 indicating the primary channel 104. Preferably, 8 bits are used.

Accordingly, the device 100 may inform any devices 200, including non-associated devices 200 operating on non-primary channels (i.e., devices that have not associated with the device 100, such as STAs 200 that have not associated with the AP 100), of the primary channel 104. Then, upon receipt of the trigger message 101, the device 200 may decide whether to switch channels and continue the network discovery process on the primary channel 104 or remain on its current non-primary channel.

In particular, any non-associated device 200 may decode the trigger message 101 in a non-primary channel (as part of its scanning). Typically (but not necessarily), the apparatus 100 only sends a probe response in the primary channel 104. In this case, typically only the device 200 located in the primary channel 104 has an opportunity to associate with the device 100. However, by indicating 103 the primary channel 104 according to the invention, any device 200 may in this case (when applicable) switch to the primary channel 104 and wait for a probe response. Alternatively, the apparatus 200 may decide not to request a probe response and keep on its current channel.

In this respect, fig. 4 shows possible options for the operation of the device 100 and 200 based on the above, as contemplated by the present invention. Fig. 4 specifically shows messages (e.g., frames) transmitted on the primary channel 104(P20) and the secondary channel 401(S20), respectively. In the figure, the message shown with hatching is transmitted by the device 200, and other messages are transmitted by the device 100.

The first option is shown in fig. 4 (a). The apparatus 100 sends a trigger message (NDP trigger) on all channels 102, i.e., the primary channel 104 and the secondary channel 401. The apparatus 200 accordingly sends an NDP response 402 on the secondary channel 401, which NDP response 402 may comprise a probe response request. The device 200 then switches to the primary channel 104 as determined from the trigger message 101. The device 200 then waits until the device 100 sends a probe response on the primary channel 104.

The second option is shown in fig. 4 (B). The apparatus 100 sends a trigger message (NDP trigger) on all channels 102, i.e., the primary channel 104 and the secondary channel 401. The apparatus 200 also sends an NDP response 402 on the secondary channel 401, which NDP response 402 may comprise a probe response request. The device 100 sends a probe response 403 on the primary channel 104. However, the device 200 switches to the primary channel 104 after that. Thus, the device 200 does not receive a probe response and sends a probe response request 400 or another NDP response 402 on the primary channel 104. Followed by another probe response 403 of the device 100, which the device 200 may receive on the primary channel 104.

A third option is shown in fig. 4 (C). The first device 100 also sends a trigger message 101 on all primary and secondary channels 102. The apparatus 200 also sends an NDP response 402 on the secondary channel 401, which NDP response 402 may comprise a probe response request. The device 100 then transmits the probe responses 403 on all channels, and the device 200 may receive the probe responses 403 on the secondary channel 401. Thereafter, the apparatus 200 may switch to the primary channel 104.

A fourth option is shown in fig. 4 (D). The first device 100 also sends a trigger message 101 on all primary and secondary channels 102. The apparatus 200 immediately switches to the primary channel 104 and sends a probe response request 400 or an NDP response 402, which probe response request 400 or NDP response 402 may comprise a probe response request on the primary channel 104. The device 100 then transmits a probe response 403 on the primary channel 104, and the device 200 may receive the probe response 403 on the primary channel 104.

Returning to fig. 3, advantageously, in each of (a), (B), (C), the user information field 300 further includes information (bit) 301, the information (bit) 301 indicating the amount of resources allocated for the probe response request. Preferably, 1 or 2 bits are used.

Accordingly, the apparatus 100 may thus inform the apparatus 200 whether some resources in each channel 102 are allocated for the probe response request. 1 or 2 bits may be used for this indication: for example, 1 bit may be used to indicate whether the last 1 (or 2) resources in each channel 102 are allocated for a probe response request. Alternatively, 2 bits may be used to indicate how many resources are allocated for probe response requests within each channel 102 (1/2/3/4).

There are different alternatives for the indication 301 of the number of resources used for the probe response request in the trigger message 101, which indication 301 is implemented by the apparatus 100 and interpreted accordingly by the apparatus 200.

In a first alternative, the above-described number of resources for probe response requests are located only on the primary channel 104 (e.g., if there are 4 20MHz channels 102 in an 80MHz bandwidth, the resources available for probe response requests are located only on the primary 20MHz channel). This means that the device 200 on the non-primary channel (secondary channel) cannot send a probe response request.

In a second alternative, the above-mentioned number of resources for the probe response request is located at the last allocation (for the entire bandwidth; e.g., if there are 4 20Mhz in the 80Mhz bandwidth, the resource allocation available for the probe response request is at the "end" of the available bandwidth). This means that a device 200 on a channel 102 that is not the last channel in the determined bandwidth (counting from top to bottom or counting from bottom to top) cannot send a probe response request.

In a third alternative, the above-mentioned number of resources is located on each channel 102. This means that for each used channel, the last resource on that channel can be allocated to a probe response request.

Returning to fig. 3, advantageously, in each of (a), (B), (C) examples, the user information field 300 further includes information (bits) 302, the information (bits) 302 indicating the location of the one or more secondary channels 401 relative to the primary channel 104. The specific implementation of the information 302 may vary for different examples of the user information field 300. Optionally, as shown in example (a), the user information field 300 may further include information (bits) 303 related to the determined bandwidth.

In particular, if the determined bandwidth is wider than the bandwidth of the channel 102, it is advantageous to include at least information 302 indicating the position of the secondary channel 401 and optionally information 303 indicating the total (determined) bandwidth. Such information 302, 303 may not be necessary if the total bandwidth is equal to the bandwidth of a single channel 102.

The information 302 may be an offset of the secondary channel (bit 302 in fig. 3(a) and 3(B), bit 302a in fig. 3 (C)). This means that the information 302 is the position of the secondary channel 401 relative to the primary channel 104. If the channel bandwidth is, for example, 20MHZ and the determined bandwidth is, for example, 40MHZ, then the information (up/down) about the secondary channel relative to the primary channel 104 is relevant. If the determined bandwidth is, for example, 80MHz, then information about the secondary 20/40MHz channel is relevant. If the bandwidth is, for example, 160MHz, then information about the secondary 20/40/80MHz channel is relevant, preferably including the center frequency of the 80MHz channel. All relevant information may be contained in other subfields.

For the information 303 (bit 303 in fig. 3 (a)) indicating the total bandwidth, 2 bits are usually sufficient.

In the case where the determined bandwidth is, for example, 80/160MHz (including 80MHz +80MHz aggregation), more information may be needed about the channel center frequency band of the primary and secondary 80MHz channels. Such information may be carried in a common information field associated with the trigger. Such trigger-related common information fields may for example comprise the subfields channel centre band 0 and channel centre band 1.

In fig. 3, the first user information field 300 example (a) is being applied to bandwidths of 20MHz and 40 MHz. For bandwidths of 80MHz and 160MHz, additional information may be carried in the common information field associated with the trigger (carrying the channel center band mentioned above).

Second user information field 300 example (B) is the same as example (a) but has no bandwidth subfield (this is not necessary as the bandwidth subfield may be carried in other signals).

The third user information field 300 example (C) is being applied to a bandwidth of 20/40/80 MHz. For a 160MHz bandwidth, additional information may be carried in the trigger related common information field (carrying the channel center band mentioned above).

Fig. 5 illustrates a method 500 according to an embodiment of the invention. The method 500 is preferably implemented in the apparatus 100 as shown in fig. 1, more preferably in an AP. The method 500 comprises the steps 501: the trigger message 101 is sent on a plurality of channels 102 within a determined bandwidth. The method 500 further includes step 502: for example, a primary channel 104 of the plurality of channels 102 is indicated in the trigger message 101 by including bit information relating to the primary channel 104 in the trigger message 101. That is, the transmitted trigger message 101 indicates the primary channel 104. Preferably, the trigger message 101 is an NDP trigger frame.

FIG. 6 illustrates a method 600 according to an embodiment of the invention. The method 600 is preferably implemented in the apparatus 200 as shown in fig. 2, and more preferably in the STA. The method 600 includes the steps 601: a trigger message 101 is received on one of a plurality of channels 102 within a determined bandwidth. Further, the method 600 comprises step 602: a primary channel 104 of the plurality of channels 102 is determined from the received trigger message 101. Preferably, the trigger message 101 is an NDP trigger frame.

In summary, the present invention achieves various advantages over conventionally used mechanisms. In particular, by enabling the apparatus 200 to request a probe response via an NDP feedback mechanism (by including a probe response request in an NDP response), several benefits are achieved. The probe response requests and probe response messages sent during network discovery are significantly reduced, thereby improving channel utilization and reducing collision probability. Furthermore, efficient reuse of NDP feedback resources not allocated to the associated apparatus 200 can be achieved. Furthermore, by transmitting the NDP trigger frame variant of the trigger message 101 in the legacy copy mode, the non-associated device 200 can find a device 100 with which it is not yet co-located even when located in the secondary channel 401, in particular, the device 200 need not scan all channels 102. Thus, the channel discovery time is significantly reduced. Furthermore, the probability of "detecting storm" effects in an HD environment is significantly reduced or even eliminated.

Furthermore, even unassociated devices 200 (e.g., STAs) may now know the locations of the primary channel 104 and the secondary channel 401, and thus, these unassociated devices 200 may send their probe request responses or request resources on existing (non-primary) channels, or switch to the primary channel 104 and continue on the primary channel 104. By preferably providing the apparatus 200 with the location of the secondary channel 401 relative to the primary channel 104, the apparatus 200 may align with the temporary AID notified by the apparatus 100.

The invention has been described in connection with various embodiments and implementations as examples. However, other variations can be understood and effected by those skilled in the art and practicing the claimed invention, from a study of the drawings, the 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 mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims (15)

1. An apparatus for transmitting a trigger message, for

Transmitting a trigger message on a plurality of channels within a determined bandwidth, wherein,

the trigger message indicates a primary channel of the plurality of channels;

wherein the trigger message is a Null Data Packet (NDP) feedback report poll, the NDP feedback report poll includes at least a user information field indicating the primary channel, and the trigger message is used to indicate that a receiving end of the trigger message switches to the primary channel.

2. The device of claim 1, wherein

The trigger message further indicates whether at least one resource is allocated for a probe response request within the plurality of channels.

3. The device of claim 1 or 2, wherein

The trigger message also indicates an amount of resources allocated for probe response requests within the plurality of channels.

4. The device of claim 3, wherein

The amount of resources allocated for the probe response request is only on the primary channel, or at the end of the determined bandwidth, or on each of the plurality of channels.

5. The device of any one of claims 1 to 4, wherein

The trigger message also indicates a location of at least one secondary channel of the plurality of channels relative to the primary channel.

6. The device of any one of claims 1 to 5, wherein

8 bits in the user information field indicate the primary channel,

1 or 2 bits in the user information field indicate the amount of resources allocated for a probe response request,

2 to 6 bits in the user information field indicate the position of the at least one secondary channel, an

2 bits in the user information field indicate the determined bandwidth with reservation.

7. An apparatus for receiving a trigger message, for

Receiving a trigger message on one of a plurality of channels within a determined bandwidth, an

Determining a primary channel of the plurality of channels from the received trigger message;

wherein the trigger message is a Null Data Packet (NDP) feedback report poll, the NDP feedback report poll including at least a user information field indicating the primary channel, the trigger message to instruct the apparatus to switch to the primary channel.

8. The apparatus of claim 7, further for

Determining, from the received trigger message, an amount and/or location of resources allocated within the plurality of channels for probe response requests.

9. The apparatus of claim 7 or 8, further for

Determining a location of at least one secondary channel of the plurality of channels relative to the primary channel from the received trigger message.

10. The apparatus of any one of claims 7 to 9, further for

Receiving the trigger message on a secondary channel of the plurality of channels,

switching to the primary channel determined from the trigger message, an

Transmitting a feedback message on the primary channel, the feedback message being an NDP feedback.

11. The apparatus of claim 9 or 10, further for

And sending a feedback message on the secondary channel receiving the trigger message.

12. A system for sending and receiving trigger messages, comprising an apparatus according to any one of claims 1 to 6 and at least one apparatus according to any one of claims 7 to 11.

13. A method for sending a trigger message, comprising,

transmitting a trigger message on a plurality of channels within a determined bandwidth, wherein the trigger message indicates a primary channel of the plurality of channels;

wherein the trigger message is a Null Data Packet (NDP) feedback report poll, the NDP feedback report poll includes at least a user information field indicating the primary channel, and the trigger message is used to indicate that a receiving end of the trigger message switches to the primary channel.

14. A method for receiving a trigger message, comprising,

receiving a trigger message on one of a plurality of channels within a determined bandwidth, an

Determining a primary channel of the plurality of channels from the received trigger message;

wherein the trigger message is a Null Data Packet (NDP) feedback report poll, the NDP feedback report poll includes at least a user information field indicating the primary channel, and the trigger message is used to indicate that a receiving end of the trigger message switches to the primary channel.

15. A computer-readable storage medium for implementing a data structure for execution by a computer, wherein

The data structure is for a trigger message of a Null Data Packet (NDP) and includes information indicating a primary channel of a plurality of channels within a determined bandwidth; wherein the trigger message is a Null Data Packet (NDP) feedback report poll, the NDP feedback report poll includes at least a user information field indicating the primary channel, and the trigger message is used to indicate that a receiving end of the trigger message switches to the primary channel.

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