Devices and methods for sounding in a wireless local area network

Abstract

An access point, AP, (110) is disclosed for providing network access to one or more non-AP stations (110a-c) associated with the AP in a wireless local area network, WLAN (100), wherein each non-AP station (110a-c) implements an automatic gain control, AGC, unit for adjusting a received signal depending on one or more AGC parameter values. The AP is configured to perform a sounding procedure with an Overlapping Basic Service Set, OBSS, AP (120), wherein in a first sounding phase of the sounding procedure the AP (110) transmits one or more sounding Null Data Packet, NDP, frames and wherein in a second sounding phase the OBSS AP transmits one or more further sounding NDP frames. The AP (110) is further configured to send a frame to the one or more non-AP stations associated with the AP, wherein the frame comprises an indication for setting the one or more AGC parameter values.

Description

[0001] DEVICES AND METHODS FOR SOUNDING IN A WIRELESS LOCAL AREA NETWORK

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to wireless communications. More specifically, the present disclosure relates to devices and methods for a sounding procedure implemented by a group of access points, APs, in a wireless communication network, in particular a wireless local area network, WLAN, (also referred to as Wi-Fi network) in accordance with the IEEE 802.11 framework of standards.

[0004] BACKGROUND

[0005] The IEEE 802.1 Ibn (UHR - Ultra High Reliability) task group is in the process of standardizing new protocols that will support coordinated beamforming schemes. In coordinated beamforming, an Access Point (AP) learns the interference channels towards OBSS (Overlapping Basic Service Set) STAs (Stations) and tries to minimize the interference to these STAs by nulling its transmission towards them during data transmission to its associated STAs.

[0006] In the normal beamforming schemes that are unaware of interference to OBSS and are supported by current 802.11 standards, it is only required to measure the direct communication channel between the beamformer (AP in downlink direction) and the beamformee (STA in downlink direction). For that purpose, the current standard defines a sounding procedure in which the beamformer sends a sounding Null Data Packet (NDP) to the beamformee, which measures the channel using this sounding NDP and sends a Beamforming Report (BFR) back to the beamformer.

[0007] SUMMARY

[0008] It is an objective of the present disclosure to provide improved devices and methods for a sounding procedure implemented by a group of access points, APs, in a wireless communication network, in particular a WLAN in accordance with the IEEE 802.11 framework of standards.

[0009] The foregoing and other objectives are achieved by the subject matter of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures. In the following one or more of the following acronyms and abbreviations may be used:

[0010] AP Access Point

[0011] BF Beamforming

[0012] BFR Beamforming Report

[0013] LAN Local Area Network

[0014] MAC Media Access Control

[0015] NDP Null Data PPDU

[0016] NDPR Null Data PPDU Request

[0017] OBSS Overlapping Basic Serving Set

[0018] PHY Physical (layer)

[0019] PPDU Physical Layer Protocol Data Unit

[0020] STA Station

[0021] UL Uplink

[0022] WLAN Wireless LAN According to a first aspect an access point, AP, is provided for providing network access to one or more non-AP stations associated with the AP in a wireless local area network, WLAN, wherein each non-AP station implements, i.e. comprises an automatic gain control, AGC, unit for adjusting a received signal depending on one or more AGC parameter values, i.e. one or more AGC settings. The AP according to the first aspect is configured to perform a sounding procedure, in particular a sequential sounding procedure, with an Overlapping Basic Service Set, OBSS, AP, wherein in a first sounding phase of the sounding procedure the AP according to the first aspect transmits one or more sounding Null Data Packet, NDP, frames and wherein in a second sounding phase the OBSS AP transmits one or more further sounding NDP frames. The AP according to the first aspect is further configured to send a frame to the one or more non-AP stations associated with the AP, wherein the frame comprises an indication for setting the one or more AGC parameter values. This frame may be sent as a part of the sounding procedure. The AP according to the first aspect supports the use of consistent AGC settings by its associated non- AP stations during the sounding procedure.

[0023] In a further possible implementation form, the indication for setting the one or more AGC parameter values is indicative of an upper limit of the one or more AGC parameter values.

[0024] In a further possible implementation form, each non-AP station comprises one or more amplifiers, in particular Low Noise Amplifiers, LNAs, for amplifying received signals, wherein the indication for setting the one or more AGC parameter values is indicative of an upper limit of a gain value of the one or more amplifiers, in particular LNAs.

[0025] In a further possible implementation form, the indication for setting the one or more AGC parameter values is indicative of using the one or more AGC parameter values used for receiving the one or more sounding NDP frames from the AP for receiving the one or more further sounding NDP frames from the OBSS AP. In other words, the indication for setting the one or more AGC parameter values may force the respective non-AP station to use the same AGC parameter values for receiving the sounding NDP frames from the AP and for receiving the further sounding NDP frames from the OBSS AP.

[0026] In a further possible implementation form, the frame is a NDP Announcement, NDPA, frame.

[0027] In a further possible implementation form, the NDPA frame is an UHR or EHT NDPA frame, wherein the UHR or EHT NDPA frame comprise a STA Info field for each of the one or more non-AP stations associated with the AP and wherein the indication is included, i.e. encoded in one or more reserved bits of each STA Info field.

[0028] In a further possible implementation form, the AP according to the first aspect is further configured to receive a Beamforming Report, BFR, frame from each of the one or more non-AP stations associated with the AP according to the first aspect, wherein each BFR frame comprises a further indication for indicating to the AP according to the first aspect that the non-AP station used one or more AGC parameter values lower than an upper limit for the one or more AGC parameter values for receiving the one or more further sounding NDP frames from the OBSS AP.

[0029] In a further possible implementation form, the BFR frame comprises a MIMO control field and the MIMO control field, in particular the reserved bits thereof, comprises the further indication.

[0030] According to a second aspect a method is disclosed for operating an access point, AP, for providing network access to one or more non-AP stations associated with the AP in a wireless local area network, WLAN, wherein each non-AP station implements, i.e. comprises an automatic gain control, AGC, unit for adjusting a received signal depending on one or more AGC parameter values, i.e. one or more AGC settings. The method according to the second aspect comprises: performing a sounding procedure, in particular a sequential sounding procedure, with an OBSS AP, wherein in a first sounding phase of the sounding procedure the AP transmits one or more sounding Null Data Packet, NDP, frames and wherein in a second sounding phase the OBSS AP transmits one or more further sounding NDP frames; and sending a frame to the one or more non-AP stations associated with the AP, wherein the frame comprises an indication for setting the one or more AGC parameter values.

[0031] The method according to the second aspect can be performed by the AP according to the first aspect. Thus, further features of the method according to the second aspect result directly from the functionality of the AP according to the first aspect, as well as its different implementation forms described above and below.

[0032] According to a third aspect a non-access point, non-AP, station for network access via an associated AP in a wireless local area network, WLAN, wherein the non-AP station implements, i.e. comprises an automatic gain control, AGC, unit for adjusting a received signal depending on one or more AGC parameter values, i.e. one or more AGC settings. The non-AP station according to the third aspect is configured to receive in a first sounding phase of a sounding procedure, in particular a sequential sounding procedure, one or more sounding Null Data Packet, NDP, frames from the associated AP and in a second sounding phase of the sounding procedure one or more further sounding NDP frames from an Overlapping Basic Service Set, OBSS, AP. The non-AP station according to the third aspect is further configured to receive from the associated AP a frame, wherein the frame comprises an indication for setting the one or more AGC parameter values. This frame may be sent by the associated AP during the sounding procedure. The non-AP station according to the third aspect supports the use of consistent AGC settings during the sounding procedure.

[0033] In a further possible implementation form, the indication for setting the one or more AGC parameter values is indicative of an upper limit of the one or more AGC parameter values.

[0034] In a further possible implementation form, the non-AP station according to the third aspect comprises one or more amplifiers, in particular Low Noise Amplifiers, LNAs, for amplifying the received signals, wherein the indication for setting the one or more AGC parameter values is indicative of an upper limit of a gain value of the one or more amplifiers, in particular LNAs.

[0035] In a further possible implementation form, the indication for setting the one or more AGC parameter values is indicative of using the one or more AGC parameter values used for receiving the one or more NDP frames from the AP for receiving the one or more further NDP frames from the OBSS AP. In other words, the indication for setting the one or more AGC parameter values may force the non-AP station according to the third aspect to use the same AGC parameter values for receiving the sounding NDP frames from the AP and for receiving the further sounding NDP frames from the OBSS AP.

[0036] In a further possible implementation form, the frame is a NDP Announcement, NDPA, frame.

[0037] In a further possible implementation form, the NDPA frame is an UHR or EHT NDPA frame and the UHR or EHT NDPA frame comprises one or more STA Info fields, wherein the indication is included, i.e. encoded in one or more reserved bits of one STA Info field of the one or more STA info fields.

[0038] In a further possible implementation form, the non-AP station according to third aspect is further configured to transmit a Beamforming Report, BFR, frame to the AP, wherein the BFR frame comprises a further indication for indicating to the AP that the non-AP station according to the third aspect used one or more AGC parameter values lower than an upper limit for the one or more AGC parameter values for receiving the one or more further NDP frames from the OBSS AP. In a further possible implementation form, the BFR frame comprises a MIMO control field and the MIMO control field, in particular the reserved bits thereof, comprises the further indication.

[0039] According to a fourth aspect a method is provided for operating a non-access point, non-AP, station for network access via an associated AP in a wireless local area network, WLAN, wherein the non-AP station implements, i.e. comprises an automatic gain control, AGC, unit for adjusting a received signal depending on one or more AGC parameter values, i.e. one or more AGC settings. The method according to fourth aspect comprises: receiving in a first sounding phase of a sounding procedure, in particular a sequential sounding procedure, one or more sounding Null Data Packet, NDP, frames from the associated AP and in a second sounding phase of the sounding procedure one or more further sounding NDP frames from an Overlapping Basic Service Set, OBSS, AP; and receiving from the associated AP a frame, wherein the frame comprises an indication for setting the one or more AGC parameter values.

[0040] The method according to the fourth aspect can be performed by the non-AP station according to the third aspect. Thus, further features of the method according to the fourth aspect result directly from the functionality of the non-AP station according to the third aspect, as well as its different implementation forms described above and below.

[0041] According to a fifth aspect a computer program product is provided, comprising program code which causes a computer or a processor to perform the method according to the second aspect or the method according to the fourth aspect, when the program code is executed by the computer or the processor.

[0042] Details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description, drawings, and claims.

[0043] BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In the following, embodiments of the present disclosure are described in more detail with reference to the attached figures and drawings, in which:

[0045] Fig. la shows a schematic diagram illustrating a WLAN including an AP according to an embodiment with a plurality of associated non-AP stations according to an embodiment and an OBSS AP with a further plurality of associated non-AP stations;

[0046] Fig. lb shows a schematic diagram illustrating the problem of interference arising in the WLAN of figure la;

[0047] Fig. 2a shows a schematic diagram illustrating different stages of a sounding procedure implemented by an AP and an OBSS AP;

[0048] Figs. 2b and 2c show schematic diagrams illustrating the problem of inconsistent AGC settings of a non-AP stations for receiving the sounding signals from an AP and an OBSS AP;

[0049] Fig. 3 shows a schematic diagram illustrating different stages of a sounding procedure implemented by an AP according to an embodiment and a non-AP station according to an embodiment; Fig. 4 shows a schematic diagram illustrating a STA info field of a NDPA frame transmitted by an AP according to an embodiment;

[0050] Fig. 5 shows a schematic diagram illustrating a MIMO control field of a BFR frame transmitted by a non-AP station according to an embodiment;

[0051] Fig. 6 shows a flow diagram illustrating a method according to an embodiment for operating an AP; and

[0052] Fig. 7 shows a flow diagram illustrating a method according to an embodiment for operating a non-AP station.

[0053] In the following, identical reference signs refer to identical or at least functionally equivalent features.

[0054] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0055] In the following description, reference is made to the accompanying figures, which form part of the disclosure, which illustrates specific aspects of embodiments of the present disclosure or specific aspects in which embodiments of the present disclosure may be used. It is understood that embodiments of the present disclosure may be used in other aspects and comprise structural or logical changes not depicted in the figures. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims.

[0056] For instance, it is to be understood that a disclosure in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if one or a plurality of specific method steps are described, a corresponding device may include one or a plurality of units, e.g. functional units, to perform the described one or plurality of method steps (e.g. one unit performing the one or plurality of steps, or a plurality of units each performing one or more of the plurality of steps), even if such one or more units are not explicitly described or illustrated in the figures. On the other hand, for example, if a specific apparatus is described based on one or a plurality of units, e.g. functional units, a corresponding method may include one step to perform the functionality of the one or plurality of units (e.g. one step performing the functionality of the one or plurality of units, or a plurality of steps each performing the functionality of one or more of the plurality of units), even if such one or plurality of steps are not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary embodiments and / or aspects described herein may be combined with each other, unless specifically noted otherwise.

[0057] Figure la shows a wireless communication system 100, in particular a wireless local area network, WLAN, 100 in accordance with the IEEE 802.11 framework of standards (also referred to as a Wi-Fi network 100). The WLAN 100 comprises an access point, AP, 110 in communication with a plurality of non-AP stations 1 lOa-c associated with the AP 110. The WLAN 100 further comprises at least one further AP 120 (which relative to the AP 110 is designated as an OBSS AP 120) in communication with a further plurality of non-AP stations 120a-c associated with the further AP 120. As illustrated in figure la, by way of example, the non-AP stations 1 lOa-c associated with the AP 110 and the further non-AP stations 120a-c, i.e. the non-AP stations 120a-c associated with the OBSS AP 120 may comprise smartphones, laptop computers, tablet computers, desktop computers or other types of wireless devices configured to be associated with an AP. As indicated in figure la, the AP 110 and the at least one OBSS AP 120 may exchange communication frames with each other and with their respective associated non-AP stations HOa-c, 120a-c.

[0058] As further illustrated in figure la, the AP 110 may comprise a processing circuitry 111 and a communication interface 113, in particular a wireless communication interface 113 enabling communication in accordance with the IEEE 802.11 framework of standards. The processing circuitry 111 may be implemented in hardware and / or software and may comprise digital circuitry, or both analog and digital circuitry. Digital circuitry may comprise components such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), or general-purpose processors. The AP 110 may further comprise a memory 115 configured to store executable program code which, when executed by the processing circuitry 111, causes the AP 110 to perform the functions and methods described herein.

[0059] Also, the OBSS AP 120 may comprise a processing circuitry 121 and a communication interface 123, in particular a wireless communication interface 123 enabling communication in accordance with the IEEE 802.11 framework of standards. The processing circuitry 121 may be implemented in hardware and / or software and may comprise digital circuitry, or both analog and digital circuitry. Digital circuitry may comprise components such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), or general-purpose processors. The OBSS AP 120 may further comprise a memory 125 configured to store executable program code which, when executed by the processing circuitry 121, causes the further AP 120 to perform the functions and methods described herein.

[0060] Likewise, each of the non-AP stations 1 lOa-c, 120a-c may comprise a processing circuitry and a communication interface (not illustrated in figure la), in particular a wireless communication interface enabling a communication in accordance with the IEEE 802.11 framework of standards. The processing circuitry may be implemented in hardware and / or software and may comprise digital circuitry, or both analog and digital circuitry. Digital circuitry may comprise components such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), or general-purpose processors. Each non-AP station 1 lOa-c, 120a-c may further comprise a memory (not illustrated in figure la) configured to store executable program code which, when executed by the processing circuitry of the non-AP station, causes the non-AP station to perform the functions and methods described herein.

[0061] As already mentioned above, the IEEE 802.11 bn (UHR - Ultra High Reliability) task group is in the process of standardizing new protocols that will support coordinated beamforming schemes. In coordinated beamforming, an AP (Access Point) learns the interference channels towards OBSS (Overlapping Basic Service Set) STAs (Stations) and tries to minimize the interference to these STAs by nulling its transmission towards them during data transmission to its associated STAs.

[0062] In the normal beamforming schemes that are unaware of interference to OBSS and are supported by the current 802.11 framework of standards, it is only required to measure the direct communication channel between the beamformer (AP in downlink direction) and the beamformee (STA in downlink direction). For that purpose, the current 802.11 framework of standards defines a sounding procedure in which the beamformer sends a sounding NDP to the beamformee, which measures the channel using this sounding NDP (Null Data Packet) and sends a BFR (Beamforming Report) back to the beamformer.

[0063] The support for coordinated beamforming schemes requires extending the sounding procedure to include measurements of the interference channel in addition to the direct communication channel. Figure lb illustrates the issue of interference for exemplary topology with two APs 110, 120 and each AP 110, 120 with a single associated STA 110a, 120a.

[0064] One of the suggested approaches for handling interference is implementing a sequential sounding procedure in which a first phase allows measuring the direct communication channel and one or more following phases allow measuring the interference channels. From an STA perspective, a given STA is first sounded by its associated AP in order to measure the direct communication channel and then sounded by one or multiple cooperating neighboring APs to allow measuring the interference channels towards the given STA. Figure 2a illustrates an exemplary sequential sounding flow, where each one of the STAs 110a, 120a is first sounded by its associated AP and then by its neighboring OBSS AP, i.e. in a first phase of the sequential sounding procedure the non-AP station 110a associated with the AP 110a is sounded, while in a second phase of the sequential sounding procedure the non-AP station 120a associated with the OBSS AP 120 is sounded. More specifically, in the first phase of the sequential sounding procedure illustrated in figure 2a the AP 110 transmits a NDPA frame 21 la and a sounding NDP frame 212a. Moreover, the AP 110 may transmit an BFRP trigger frame 213a for triggering the non-AP station 110a to transmit a BFR frame 214a based on the sounding NDP frame 212a. For sounding by the OBSS AP 120 during the first phase of the sequential sounding procedure the AP 110 transmits a NDPA frame 211b and the OBSS AP 120 transmits a sounding NDP frame 212b. Again, the AP 110 may transmit an BFRP trigger frame 213b for triggering the non-AP station 110a to transmit a BFR frame 214b based on the sounding NDP frame 212b.

[0065] In the second phase of the sequential sounding procedure illustrated in figure 2a the OBSS AP 120 transmits a NDPA frame 221a and a sounding NDP frame 222a. Moreover, the OBSS AP 120 may transmit an BFRP trigger frame 223a for triggering the non-AP station 120a (associated with the OBSS AP 120) to transmit a BFR frame 224a based on the sounding NDP frame 222a. For sounding by the AP 110 during the second phase of the sequential sounding procedure the OBSS AP 120 transmits aNDPA frame 221b and the AP 110 transmits a sounding NDP frame 222b. Again, the OBSS AP 120 may transmit an BFRP trigger frame 223b for triggering the non-AP station 120a to transmit a BFR frame 224b based on the sounding NDP frame 222b.

[0066] As will be appreciated, in the sequential sounding procedure illustrated in figure 2a, each non-AP station 110a, 120a is sounded separately by multiple APs 110, 120 and therefore the received signal power at the non-AP station 110a, 120a can vary between multiple sounding APs 110, 120. As a result, the Automatic Gain Control (AGC) settings, i.e. parameter values of the non-AP station 110a, 120a also may vary when sounded by multiple APs 110, 120, as illustrated in figures 2b, c. In a practical implementation, a change in the AGC settings doesn’t preserve a consistent gain and delay change across the RX amplifiers of the multiple antennas RX chains. Since the channel measured by the STA includes the RX amplifiers, inconsistent AGC settings across sounding stages will result in measurement and feedback based on inconsistent channel. This could severely degrade the data goodput performance of coordinated beamforming applied based on the sounding feedback results. This issue is addressed by embodiment disclosed herein.

[0067] As already described above, the AP 110 is configured to provide network access to the non-AP stations 1 lOa-c associated with the AP 110 in the WLAN 100. Each non-AP station 1 lOa-c implements, i.e. comprises an automatic gain control, AGC, unit for adjusting a received signal depending on one or more AGC parameter values. The AP 110 is configured to send a frame to the non-AP stations 1 lOa-c associated with the AP 110, wherein the frame comprises an indication for setting the one or more AGC parameter values by each non-AP station 1 lOa-c. In an embodiment, the AP 110 may send the frame with the indication for setting the one or more AGC parameter values during the sequential sound procedure. As will be described in more detail below in the context of figure 3, in the embodiment the frame with the indication for setting the one or more AGC parameter values may be the NDPA frame 21 la,b, 221a,b.

[0068] As will be appreciated, by transmitting the frame with the indication for setting the one or more AGC parameter values the AP 110 (or equivalently the OBSS AP 120 in a further sounding phase) may apply consistent AGC settings at a given non- AP station 1 lOa-c, 120a-c across the multiple sounding phases corresponding to the multiple APs 110, 120. In order to avoid the risk of saturation at the respective non-AP station 1 lOa-c, 120a-c, according to an embodiment the consistent AGC settings, i.e. parameter values may correspond to the highest receive signal among all sounding APs 110, 120.

[0069] Figure 3 illustrates a sequential sounding procedure implemented by the APs 110, 120 and the non-AP stations 110a, 120a according to an embodiment allowing to keep consistent AGC settings during the different phases of the sounding procedure. In the first phase of the sounding procedure, where the non-AP station 110a is sounded by its associated AP 110 first, the indication for setting the one or more AGC parameter values may instruct the non-AP station 110a to adjusts its AGC settings normally by adapting to the received signal power (as indicated by 315 in figure 3). The non-AP station 110a may store the resulting AGC settings, i.e. AGC parameter values, in particular a gain value in memory. In the following phases where the non-AP station 110a is sounded by neighboring OBSS APs 120, the indication for setting the one or more AGC parameter values may instruct the non-AP station 110a to use the saved AGC settings as an upper limit to the current AGC settings, in particular an upper limit to a gain value (as indicated by 316 in figure 3). This procedure is repeated for the sounding of the non-AP station 120a associated with the OBSS AP 120, i.e. when the non-AP station 120a is sounded by its associated AP 120 first, the indication for setting the one or more AGC parameter values may instruct the non-AP station 120a to adjusts its AGC settings normally by adapting to the received signal power (as indicated by 325 in figure 3). The non-AP station 120a may store the resulting AGC settings, i.e. AGC parameter values, in particular a gain value in memory. In the following phases where the non-AP station 120a is sounded by, for instance, the AP 110, the indication for setting the one or more AGC parameter values may instruct the non-AP station 120a to use the saved AGC settings as an upper limit to the current AGC settings, in particular an upper limit to a gain value (as indicated by 326 in figure 3).

[0070] As will be appreciated, in a typical case, where the received signal power levels from neighboring APs are lower than the received signal power level from the associated AP, the upper limit for the AGC parameter values keeps the AGC settings consistent with the first phase settings. In a rare case where the received signal power level from one of the neighboring APs is higher than the received signal power level from the associated AP, the AGC settings may be adjusted by the non-AP station 110a, 120a to a value below the upper limit. In an embodiment, the non-AP station 110a, 120a is configured to notify the associated AP 110, 120 about setting an inconsistent AGC parameter value below the upper limit. Once the associated AP 110, 120 has been informed in this way, the associated AP 110, 120 may choose to restart the sequential sounding procedure based on a new upper limit for the AGC parameter values that corresponds to one of the neighboring APs.

[0071] Embodiments disclosed herein may be implemented by adding signaling bits to the existing sounding protocol messages illustrated in figure 2a. These signaling bits allow applying a sequential sounding flow with consistent AGC settings in the non-AP station 110a, 120a.

[0072] As alreadv mentioned above, in an embodiment the AP 110, 120 may include the indication for setting the one or more AGC parameter values in one or more of the NDPA frames 21 la,b, 221a, b. In other words, in an embodiment, using one or more signaling bits in one or more of the NDPA frames 21 la,b, 221a,b, the sounding AP 110 may instruct its associated non-AP station 110a to apply an upper limit for the AGC settings, i.e. AGC parameter values, in particular a gain value during the following NDP reception for the purpose of attempting consistent gain across sequential sounding. In an embodiment, a bit state 0 of the signaling bit may indicate to the associated non-AP station 110a to not apply an upper limit to the AGC settings, i.e. AGC parameter values for the next NDP reception and to store the resulting AGC settings in memory for following NDP receptions. The bit state 1 of the signaling bit may indicate to the associated non-AP station 110a to apply an upper limit to the AGC settings for the next NDP reception. The gain upper limit may be based on the memory stored value from the latest NDP reception that required an update of the stored value. If the resulting AGC settings gain is lower than the upper limit, the non-AP station 110a may store the resulting AGC settings in memory for following NDP receptions.

[0073] Figure 4 shows a schematic diagram illustrating a STA info field 400 of a NDPA frame 21 la,b transmitted by the AP 110 according to an embodiment. According to an embodiment, one or more of the reserved bits 403, 408 may comprise the signaling bit(s) encoding the indication for setting the one or more AGC parameter values. The STA info field 400 may further comprise one or more of the following subfields, as defined by the current or a further IEEE 802.11 framework of standards: AID11 401, Partial BW Info 402, Nc index 404, Feedback Type And Ng 405, Disambiguation 406, and / or Codebook Size 407.

[0074] In a further embodiment, by using the signaling bit, i.e. indication in the NDPA 21 la,b, the sounding AP 110 may instruct its associated non-AP station 110a to force the AGC settings, i.e. AGC parameters values during the following NDP reception for the purpose of attempting consistent AGC settings, in particular gain settings across sequential sounding. In an embodiment, a bit state 0 of the signaling bit may indicate to the associated non-AP station 110a to not force the AGC settings for the nextNDP reception and to store the resulting AGC settings in memory for following NDP receptions. The bit state 1 of the signaling bit may indicate to the associated non-AP station 110a to force the AGC settings for the next NDP reception based on the memory stored value from one of previous NDP receptions.

[0075] Figure 5 shows a schematic diagram illustrating a MIMO control field 500 of a BFR frame 214a, b transmitted by the non-AP station 110a according to an embodiment. Using, for instance, two signaling bits in the BFR 214a,b, the sounded non-AP station 110a may inform the associated AP 110 about the AGC settings used during latest NDP reception. In an embodiment, a bit state 0 may indicate that the AGC settings were adjusted normally without any upper limit. A bit state 1 may indicate that the AGC settings upper limit was applied during the latest NDP reception and that the resulting AGC settings were equal to the upper limit. A bit state 2 may indicate that the AGC settings upper limit was applied during the latest NDP reception and that the resulting AGC settings were below the upper limit. In an embodiment, these two signaling bits for reporting back to the AP 110 may be included by the non-AP station 110a in the reserved bits 506, 512 of the MIMO control field 500 of a BFR frame 214a, b. The MIMO control field 500 may further comprise one or more of the following subfields, as defined by the current or a further IEEE 802.11 framework of standards: Nc Index 501 , Nr Index 502, BW 503, Grouping 504, Feedback Type 505, Remaining Feedback Segments 507, First Feedback Segment 508, Partial BW Info 509, Sounding Dialog Token Number 510, and / or Codebook Information 511.

[0076] In a further embodiment, the sounded non-AP station 110a may be using only a single signaling bit in the BFR frame 214a,b for notifying the associated AP 110 about what the non-AP station 110a has applied with respect to the AGC settings during the latest NDP reception. A bit state 0 may indicate that the AGC settings were adjusted normally without any forced value, while a bit state 1 may indicate that a forced value was applied for the AGC settings, in particular the gain during the latest NDP. In an embodiment, this single signaling bit for reporting back to the AP 110 may be included by the non-AP station 110a in the reserved bits 506, 512 of the MIMO control field 500 of a BFR frame 214a, b.

[0077] Figure 6 shows a flow diagram illustrating a method 600 for operating the AP 110 for providing network access to the non- AP stations 1 lOa-c associated with the AP 110 in the WLAN 100, wherein each non-AP station 1 lOa-c implements an automatic gain control, AGC, unit for adjusting a received signal depending on one or more AGC parameter values. The method 600 comprises performing 601 a sounding procedure with the OBSS AP 120, wherein, as already described above in the context of figure 3, in a first sounding phase of the sounding procedure the AP 110 transmits one or more sounding NDP frames 212a: 222b and wherein in a second sounding phase the OBSS AP 120 transmits one or more further sounding NDP frames 212b: 222a. The method 600 further comprises during the sounding procedure sending 601a a frame, in particular the NDPA frame 21 la,b to the non-AP stations 1 lOa-c associated with the AP 110, wherein the frame, in particular the NDPA frame 21 la,b, comprises an indication for setting the one or more AGC parameter values of each non-AP station 1 lOa-c.

[0078] Figure 7 shows a flow diagram illustrating a method 700 for operating any one of the non-AP stations 1 lOa-c for network access via the associated AP 110 in the WLAN 100, wherein each non-AP station 1 lOa-c implements an AGC unit for adjusting a received signal depending on one or more AGC parameter values. The method 700 comprises receiving 701 in a first sounding phase of a sounding procedure one or more sounding NDP frames 212a: 222b from the associated AP 110 and in a second sounding phase of the sounding procedure one or more further sounding NDP frames 212b: 222a from the OBSS AP 120. The method 700 further comprises during the sounding procedure receiving 701a from the associated AP 110 a frame, in particular a NDPA frame 21 la,b, wherein the frame, in particular the NDPA frame 21 la,b, comprises an indication for setting the one or more AGC parameter values of each non-AP station 1 lOa-c.

[0079] The person skilled in the art will understand that the "blocks" ("units") of the various figures (method and apparatus) represent or describe functionalities of embodiments of the present disclosure (rather than necessarily individual "units" in hardware or software) and thus describe equally functions or features of apparatus embodiments as well as method embodiments (unit = step).

[0080] In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus, and method may be implemented in other manners. For example, the described embodiment of an apparatus is merely exemplary. For example, the unit division is merely logical function division and may be another division in an actual implementation. For example, a plurality of units or components may be combined or integrated into another system, or some features may be ignored or not performed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections may be implemented by using some interfaces. The indirect couplings or communication connections between the apparatuses or units may be implemented in electronic, mechanical, or other forms. The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one position, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the objectives of the solutions of the embodiments.

[0081] In addition, functional units in the embodiments of the disclosure may be integrated into one processing unit, or each of the units may exist alone physically, or two or more units are integrated into one unit.

Claims

CLAIMS1. An access point, AP, (110) for providing network access to one or more non-AP stations (1 lOa-c) associated with the AP (110) in a wireless local area network, WLAN (100), each non-AP station (1 lOa-c) implementing an automatic gain control, AGC, unit for adjusting a received signal depending on one or more AGC parameter values, wherein the AP (110) is configured to: perform a sounding procedure with an Overlapping Basic Service Set, OBSS, AP (120), wherein in a first sounding phase of the sounding procedure the AP (110) transmits one or more sounding Null Data Packet, NDP, frames (212a; 222b) and wherein in a second sounding phase the OBSS AP (120) transmits one or more further sounding NDP frames (212b; 222a); wherein the AP (110) is further configured to send a frame (21 la,b; 221a, b) to the one or more non-AP stations (1 lOa-c) associated with the AP (110), wherein the frame comprises an indication for setting the one or more AGC parameter values.

2. The AP (110) of claim 1, wherein the indication for setting the one or more AGC parameter values is indicative of an upper limit of the one or more AGC parameter values.

3. The AP (110) of claim 1 or 2, wherein each non-AP station (1 lOa-c) comprises one or more amplifiers and wherein the indication for setting the one or more AGC parameter values is indicative of an upper limit of a gain value of the one or more amplifiers.

4. The AP (110) of any one of the preceding claims, wherein the indication for setting the one or more AGC parameter values is indicative of using the one or more AGC parameter values used for receiving the one or more sounding NDP frames (212a; 222b) for receiving the one or more further sounding NDP frames (212b; 222a).

5. The AP (110) of any one of the preceding claims, wherein the frame (21 la,b; 221a, b) is a NDP Announcement, NDPA, frame (21 la,b; 221a, b).

6. The AP (110) of claim 5, wherein the NDPA frame (21 la,b; 221a, b) is an UHR or EHT NDPA frame and wherein the UHR or EHT NDPA frame comprise a STA Info field (400) for each of the one or more non-AP stations (1 lOa-c) associated with the AP (110), wherein the indication is included in one or more reserved bits (403, 408) of the respective STA Info field (400).

7. The AP (110) of any one of the preceding claims, wherein the AP (110) is further configured to receive a Beamforming Report, BFR, frame (214a) from each of the one or more non-AP stations (1 lOa-c) associated with the AP (110) and wherein each BFR frame (214a) comprises a further indication for indicating to the AP (110) that the non-AP station (1 lOa-c) used one or more AGC parameter values lower than an upper limit for the one or more AGC parameter values for receiving the one or more further NDP frames (212b; 222a).

8. The AP (110) of claim 7, wherein the BFR frame (214a) comprises a MIMO control field (500) and wherein the MIMO control field (500) comprises the further indication.

9. A method (600) for operating an access point, AP, (110) for providing network access to one or more non-AP stations (1 lOa-c) associated with the AP (110) in a wireless local area network, WLAN (100), each non-AP station (1 lOa-c)implementing an automatic gain control, AGC, unit for adjusting a received signal depending on one or more AGC parameter values, wherein the method (600) comprises: performing (601) a sounding procedure with an Overlapping Basic Service Set, OBSS, AP (120), wherein in a first sounding phase of the sounding procedure the AP (110) transmits one or more sounding Null Data Packet, NDP, frames (212a; 222b) and wherein in a second sounding phase the OBSS AP (120) transmits one or more further sounding NDP frames (212b; 222a); and sending (601a) a frame (21 la,b) to the one or more non-AP stations (1 lOa-c) associated with the AP (110), wherein the frame (21 la,b) comprises an indication for setting the one or more AGC parameter values.

10. A non-access point, non-AP, station (1 lOa-c) for network access via an associated AP (110) in a wireless local area network, WLAN (100), wherein the non-AP station (1 lOa-c) implements an automatic gain control, AGC, unit for adjusting a received signal depending on one or more AGC parameter values, wherein the non-AP station (1 lOa-c) is configured to: receive in a first sounding phase of a sounding procedure one or more sounding Null Data Packet, NDP, frames (212a; 222b) from the associated AP (110) and in a second sounding phase of the sounding procedure one or more further sounding NDP frames (212b; 222a) from an Overlapping Basic Service Set, OBSS, AP (120); wherein the non-AP station (1 lOa-c) is further configured to receive from the associated AP (110) a frame (21 la,b), wherein the frame (21 la,b) comprises an indication for setting the one or more AGC parameter values.

11. The non-AP station (1 lOa-c) of claim 10, wherein the indication for setting the one or more AGC parameter values is indicative of an upper limit of the one or more AGC parameter values.

12. The non-AP station (1 lOa-c) of claim 10 or 11, wherein the non-AP station (1 lOa-c) comprises one or more amplifiers and wherein the indication for setting the one or more AGC parameter values is indicative of an upper limit of a gain value of the one or more amplifiers.

13. The non-AP station (1 lOa-c) of any one of the claims 10 to 12, wherein the indication for setting the one or more AGC parameter values is indicative of using the one or more AGC parameter values used for receiving the one or more sounding NDP frames (212a; 222b) for receiving the one or more further sounding NDP frames (212b; 222a).

14. The non-AP station (HOa-c) of any one of claims 10 to 13, wherein the frame (211a,b) is a NDP Announcement, NDPA, frame (21 la, b).

15. The non-AP station (1 lOa-c) of claim 14, wherein the NDPA frame (21 la,b) is an UHR or EHT NDPA frame and wherein the UHR or EHT NDPA frame comprise one or more STA Info fields (400), wherein the indication is included in one or more reserved bits (403, 408) of one STA Info field of the one or more STA info fields.

16. The non-AP station (1 lOa-c) of any one of claims 10 to 15, wherein the non-AP station (1 lOa-c) is further configured to transmit a Beamforming Report, BFR, frame (214a) to the associated AP (110) and wherein the BFR frame (214a) comprises a further indication for indicating to the associated AP (110) that the non-AP station (1 lOa-c) used one or more AGC parameter values lower than an upper limit for the one or more AGC parameter values for receiving the one or more further NDP frames (212b; 222a).

17. The non-AP station (1 lOa-c) of claim 16, wherein the BFR frame (214a) comprises a MIMO control field (500) and wherein the MIMO control field (500) comprises the further indication.

18. A method (700) for operating a non-access point, non-AP, station (HOa-c) for network access via an associated AP (110) in a wireless local area network, WLAN (100), wherein the non-AP station (1 lOa-c) implements an automatic gain control, AGC, unit for adjusting a received signal depending on one or more AGC parameter values, wherein the method (700) comprises: receiving (701) in a first sounding phase of a sounding procedure one or more sounding Null Data Packet, NDP, frames 1'212a: 222b) from the associated AP (110) and in a second sounding phase of the sounding procedure one or more further sounding NDP frames 1'212b: 222a) from an Overlapping Basic Service Set, OBSS, AP (120); and receiving (701a) from the associated AP (110) a frame (21 la,b), wherein the frame (21 la,b) comprises an indication for setting the one or more AGC parameter values.

19. A computer program product comprising a computer-readable storage medium for storing program code which causes a computer or a processor to perform the method (600) of claim 9 or the method (700) of claim 18, when the program code is executed by the computer or the processor.

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