Devices and methods for coordinated transmission in a wireless 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 (110) and for sharing communication resources of the AP (110) with one or more OBSS APs (120) in a Multi-AP, MAP, coordinated transmission under a common MAP coordination agreement, when the AP (110) obtains a transmission opportunity, TXOP. The AP (110) is configured to transmit a frame (130) to the one or more OBSS APs (120) and / or receive a frame (130) from the one or more OBSS APs (120). The frame (130) comprises an UL Response Parameters Information Element, wherein the UL Response Parameters Information Element (140) indicates one or more UL Response Parameters for controlling one or more UL responses of one or more non-AP stations (120a-c) associated with the respective OBSS AP (120) for a DL Data PPDU.

Description

[0001] DEVICES AND METHODS FOR COORDINATED TRANSMISSION IN A WIRELESS NETWORK

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to wireless communications. More specifically, the present disclosure relates to devices and methods for coordinated transmission between 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] Coordinated Beamforming, CoBF, was accepted as a Multi-AP, MAP, coordination scheme for a next generation of the IEEE 802.11 framework of standards. According to the CoBF scheme, APs transmit concurrent DL PPDUs to their associated non- AP stations while mutual interference for the OBSS non-AP stations is minimized using beamforming techniques (therefore also referred to as coordinated transmission). Once it has discovered other OBSS APs which support M-AP Coordinated transmission capability, an initiating AP starts a negotiation for an agreement with the other OBSS APs that support the same coordination scheme, specifically, the CoBF scheme. After an agreement is set between the involved OBSS APs, each of the APs performs a CoBF Sounding procedure to obtain the channel information feedback between itself, the associated non-AP stations and the non-AP stations associated with other OBSS APs that are involved in the imminent CoBF transmission. Each AP computes a precoder based on the received channel information feedback that ensures minimal interference to the OBSS stations. After receiving one or more CoBF DL PPDUs each station is assumed to respond with at least an acknowledgement PPDU. A single transmission opportunity, TXOP, may include several DL CoBF PPDUs and several UL responses.

[0006] SUMMARY

[0007] It is an objective of the present disclosure to provide improved devices, in particular access points, APs, and methods allowing for a more efficient exchange of control information in a coordinated transmission scheme between 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.

[0008] 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:

[0009] A-MPDU Aggregated MPDU

[0010] AP Access Point

[0011] BF Beamforming

[0012] BW Bandwidth

[0013] CoBF Coordinated Beamforming

[0014] CSI Channel State Information

[0015] DL Downlink

[0016] LAN Local Area Network

[0017] MAP Multiple Access Points

[0018] MAC Media Access Control MIMO Multiple In Multiple Out

[0019] MPDU MAC Protocol Data Unit

[0020] NDP Null Data PPDU

[0021] NDPR Null Data PPDU Request

[0022] OBSS Overlapping Basic Serving Set

[0023] OFDMA Orthogonal Frequency-Division Multiple Access

[0024] PER Packet Error Ratio

[0025] PHY Physical (layer)

[0026] PPDU Physical Layer Protocol Data Unit

[0027] RU Resource Unit

[0028] SNR Signal to Noise Ratio

[0029] STA Station

[0030] SVD Single Value Decomposition

[0031] TB Trigger Based

[0032] TDMA Time Division Multiple Access

[0033] TF Trigger Frame

[0034] TXOP Transmit Opportunity

[0035] UL Uplink

[0036] WLAN Wireless LAN

[0037] 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 and for sharing communication resources of the AP with one or more overlapping basic service set, OBSS, APs in a Multi-AP, MAP, coordinated transmission under a common, i.e. the same M-AP coordination agreement, when the AP obtains a transmission opportunity, TXOP. The access point according to the first aspect sharing its communication resources with the OBSS APs may be referred to as sharing AP, while the OBSS APs may be referred to as shared APs. As will be appreciated being a sharing AP or a shared AP is a role that may be assumed temporarily, for instance, for the duration of a TXOP, by a respective AP and that may change in another TXOP, e.g. in another TXOP the former sharing AP may become a shared AP, while a former shared AP may become the sharing AP (i.e. if it is the AP that has obtained the TXOP).

[0038] The AP according to the first aspect is configured to transmit a frame to the one or more OBSS APs and / or receive a frame from the one or more OBSS APs, wherein the frame comprises an UL Response Parameters Information Element and wherein the UL Response Parameters Information Element indicates, e.g. encodes for each of the one or more OBSS APs one or more UL Response Parameters for controlling one or more UL responses of one or more non-AP stations associated with the respective OBSS AP for a DL Data PPDU. Thus, by means of the UL Response Parameters Information Element the AP according to the first aspect may efficiently exchange control information with the one or more OBSS APs. More specifically, the UL Response Parameters Information Element transmitted and / or received by the AP according to the first aspect enable managed UL responses, for instance, to CoBF DL PPDUs for multiple non-AP stations from different OBSSs. Moreover, the UL Response Parameters Information Element allows negotiation of UL response parameters between participating APs and efficiently supports various UL response transmission methods, as will be described in more detail below.

[0039] In a further possible implementation form, the one or more UL responses of the one or more non-AP stations are OFDMA- based UL responses and the UL Response Parameters Information Element comprises a single UL Response Duration field indicative of a duration of one or more PPDUs used for the UL response by one or more associated non-AP stations involved in the preceding DL Data PPDUs. In a further possible implementation form, for each of the one or more OBSS APs the UL Response Parameters Information Element comprises a Bandwidth, BW, Portion field, wherein each BW Portion field is indicative of a respective BW portion of a transmission BW that is available for the respective OBSS AP for allocation to the one or more associated non-AP stations of the respective OBSS AP for the purpose of the UL response.

[0040] In a further possible implementation form, for each of the one or more OBSS APs the UL Response Parameters Information Element further comprises an AP ID field indicative of the respective OBSS AP corresponding to the respective BW Portion field.

[0041] In a further possible implementation form, the one or more UL responses of the one or more non-AP stations are EDMA-based UL responses, wherein for each of the one or more OBSS APs the UL Response Parameters Information Element comprises an UL Response Duration field and wherein each UL Response Duration field is indicative of a total duration of one or more PPDUs used for the UL Response that is available for the respective OBSS AP to receive the one or more UL Responses of the one or more non-AP stations associated with the respective OBSS AP.

[0042] In a further possible implementation form, for each of the one or more OBSS APs the UL Response Parameters Information Element further comprises an AP ID field indicative of the respective OBSS AP corresponding to the respective UL Response Duration field.

[0043] In a further possible implementation form, the UL Response Parameters Information Element comprises an Explicit BAR field indicative of one or more of the OBSS APs to use a “Block Ack” ACK Policy in each of their data frames contained in the DL PPDU that are transmitted to their associated non-AP stations.

[0044] In a further possible implementation form, each of the one or more non-AP stations associated with each OBSS AP is configured to transmit the UL Response according to a plurality of different UL Response methods or modes and the UL Response Parameters Information Element comprises a Control field and a list of a plurality of Method Specific fields, wherein the Control field is indicative of one or more of the control parameters and wherein the one or more Method Dependent Info List field comprises one or more method dependent parameters specific for the respective UL Response method or mode.

[0045] In a further possible implementation form, the Control field indicates one or more UL response schemes or methods (for instance, an OFDMA-based UL response scheme) to be used by the associated non-AP stations of the respective OBSS AP(s).

[0046] In a further possible implementation form, the Control field contains a bitmap or a bit code indicative of the one or more UL response schemes (for instance, an OFDMA-based scheme) to be used by the associated non-AP stations of the respective OBSS AP(s).

[0047] In a further possible implementation form, the Control field comprises an indication of the number of Method Dependent subfields in the Method Dependent Info List field.

[0048] In a further possible implementation form, the one or more fields in the Method Dependent Info List comprises a Common field containing one or more parameters common for the OBSS APs and for each OBSS AP a Per-AP Info field containing one or more parameters for the respective OBSS AP.

[0049] In a further possible implementation form, the Common field comprises an Explicit BAR field indicative of one or more of the OBSS APs to use a “Block Ack” ACK Policy in each of their data frames contained in the DL PPDU that are transmitted to their associated non-AP stations. In a further possible implementation form, for the case of OFDMA-based UL Response scheme, the Common field comprises an UL Response Duration subfield indicative of a duration of the one or more PPDUs used for UL response by one or more associated non-AP stations involved in the preceding DL Data PPDU.

[0050] In a further possible implementation form, the AP Dependent Info field for each of the one or more OBSS APs comprises a Bandwidth, BW, Portion subfield, wherein each BW Portion subfield is indicative of a respective BW portion of a transmission BW that is available for the respective OBSS AP for allocation to the one or more associated non-AP stations of the respective OBSS AP for the purpose of the UL response.

[0051] In a further possible implementation form, for each of the one or more OBSS APs the AP Dependent Info field further comprises an AP ID subfield indicative of the OBSS AP corresponding to the respective BW Portion subfield.

[0052] In a further possible implementation form, the one or more UL responses of the one or more non-AP stations are one or more sequential TDMA based UL responses, wherein for each of the one or more OBSS APs the Per AP Info field comprises a UL Response Duration subfield and wherein each UL Response Duration subfield is indicative of a total duration of the UL Response that is allocated for the respective OBSS AP to receive the one or more UL Responses of the one or more non-AP stations associated with the respective OBSS AP.

[0053] In a further possible implementation form, for each of the one or more OBSS APs the Per Info field further comprises an AP ID subfield indicative of the respective OBSS AP corresponding to the respective UL Response Duration subfield.

[0054] In a further possible implementation form, the AP according to the first aspect is configured to include the UL Response Parameters Information Element within a transmitted frame to the one or more OBSS APs.

[0055] In a further possible implementation form, the transmitted frame is a MAP Announcement Request Frame or a MAP Coordination Agreement setting Request frame.

[0056] In a further possible implementation form, the AP according to the first aspect is configured to include the UL Response Parameters Information Element within a transmitted frame when it is shared in a PXOP by a sharing AP.

[0057] In a further possible implementation form, the transmitted frame is a MAP Announcement Response Frame or a MAP Coordination Agreement setting Response frame.

[0058] In a further possible implementation form, the AP according to the first aspect is configured to include the UL Response Parameters Information Element within a transmitted frame to the one or more OBSS APs, wherein the frame is a MAP Prigger Frame, MAP TF, for indicating one or more UL Response control parameters to be used by the non-AP stations associated with a respective OBSS AP for transmitting the UL Response to a CoBF DL PPDU triggered by the MAP TF.

[0059] According to a second aspect a method is provided for operating an access point, AP, for providing network access to one or more non-AP stations associated with the AP and for sharing communication resources of the AP with one or more OBSS APs (herein also referred to as shared APs) under a common, i.e. the same M-AP coordination agreement in a Multi-AP, MAP, coordinated transmission, when the AP obtains a transmission opportunity, TXOP. The method according to the second aspect comprises: transmitting a frame to the one or more OBSS APs and / or receiving a frame from the one or more OBSS APs, wherein the frame comprises an UL Response Parameters Information Element and wherein the UL Response Parameters Information Element indicates for each of the one or more OBSS APs one or more UL Response Parameters for controlling the UL response of one or more non-AP stations associated with the respective OBSS AP for a DL Data PPDU.

[0060] 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.

[0061] According to a third 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, when the program code is executed by the computer or the processor.

[0062] 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.

[0063] BRIEF DESCRIPTION OF THE DRAWINGS

[0064] In the following, embodiments of the present disclosure are described in more detail with reference to the attached figures and drawings, in which:

[0065] Fig. 1 shows a schematic diagram illustrating a wireless communication network, in particular a WLAN including an AP according to an embodiment with a plurality of associated non-AP stations and an OBSS AP with a further plurality of associated non-AP stations;

[0066] Fig. 2 shows a schematic diagram illustrating different stages of a Coordinated Beamforming (CoBF) scheme implemented by an AP according to an embodiment, a non-AP station associated with the AP, an OBSS AP and a non-AP station associated with the OBSS AP;

[0067] Figs. 3a and 3b show respective schematic diagrams illustrating UL Response methods within the time-frequency domain based on OFDMA and TDMA, respectively;

[0068] Fig. 4 shows a schematic diagram illustrating a frame transmitted by an AP according to an embodiment to an OBSS AP, wherein the frame comprises a UL Response Parameters Information Element;

[0069] Fig. 5 shows a schematic diagram illustrating in more detail a UL Response Parameters Information Element according to an embodiment for an OFDMA based UL Response method;

[0070] Fig. 6 shows a schematic diagram illustrating in more detail a UL Response Parameters Information Element according to an embodiment for a TDMA based UL Response method;

[0071] Fig. 7 shows a schematic diagram illustrating in more detail a UL Response Parameters Information Element for an embodiment with several different UL Response methods;

[0072] Fig. 8 shows a schematic diagram illustrating in more detail a Method Dependent Info fields of an UL Response Parameters Information Element for an embodiment with several different UL Response methods for an OFDMA based UL Response method; Fig. 9 shows a schematic diagram illustrating in more detail a Method Dependent Info fields of an UL Response Parameters Information Element for an embodiment with several different UL Response methods for a TDMA based UL Response method; and

[0073] Fig. 10 shows a flow diagram illustrating steps of a method according to an embodiment for operating an AP.

[0074] In the following, identical reference signs refer to identical or at least functionally equivalent features.

[0075] DEPAILED DESCRIPPION OF THE EMBODIMENTS

[0076] 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. Phe 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.

[0077] 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.

[0078] Figure 1 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). Ehe WLAN 100 comprises an access point, AP, 110 in communication with a plurality of non-AP stations HOa-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 1, by way of example, the non-AP stations HOa-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 1 , the AP 110 may exchange one or more frames 130 with the OBSS AP 120.

[0079] As further illustrated in figure 1, 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. 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.

[0080] 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 1 ), 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 1) 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.

[0081] The AP 110 and the at least one OBSS AP 120 are configured to implement one or more Multi-AP, MAP, coordinated transmission schemes. In an embodiment, the one or more MAP coordinated transmission schemes may comprise Coordinated Beamforming, CoBF, which was accepted as MAP coordination scheme for a next generation of the IEEE 802.11 framework of standards. Figure 2 shows a schematic diagram illustrating different stages of a CoBF scheme, which may be implemented by the AP 110 according to an embodiment, the non-AP station 110a associated with the AP 110, the at least one OBSS AP 120 and the non-AP station 120a associated with the OBSS AP 120. As can be taken from figure 2, during a TXOP 200 the CoBF scheme may include an announcement stage 210, a pre-transmission stage 220, and a CoBF transmission stage 230. In the announcement stage 210 the AP 110 sends a MAP Announcement frame 211 to the one or more OBSS APs, which respond with a MAP Announcement Response frame 213. In the announcement stage 210 the initiating AP 110 requests the OBSS AP(s) 120, with which it has an agreement for MAP CoBF scheme, to participate in the imminent CoBF transmission and it is responded by the OBSS AP 120 whether it can participate in such MAP coordinated transmission. In the pre-transmission stage 220 the AP 110 may trigger a CoBF sounding procedure 223 by means of a MAP TF 221. In the CoBF sounding procedure 223 each the AP 110 and the at least one OBSS AP 120 perform a sounding procedure to obtain the channel information feedback between itself, the associated non-AP stations 110a and the non-AP stations 120a associated with other OBSS APs 120 involved in the imminent CoBF transmission. Each AP 110, 120 computes a precoder based on the received channel information feedback that ensures minimal interference to the OBSS stations 110a, 120a. In the CoBF transmission stage 230, the AP 110 and the at least one OBSS AP 120 (following a further MAP TF 231a, b from the AP 110) transmit concurrent DL PPDUs 233a, b to their associated non-AP stations 110a, 120a while mutual interference for the OBSS non-AP stations is minimized using beamforming techniques, i.e. the precoders determined by means of the CoBF sounding procedure 223. After receiving one or more CoBF DL PPDUs 233a, b each station 110a, 120a is assumed to respond with at least an acknowledgement PPDU in the form of a UL Response frame 235a, b. As illustrated in figure 2, the single TXOP 200 may include several DL CoBF PPDUs 233a and 233b and several UL responses 235a and 235b.

[0082] Although the details of CoBF DL PPDU transmissions 233a, b have been widely discussed for a next generation of the IEEE 802.11 framework of standards, the UL responses 235a, b have not been investigated properly yet. As will be described in more detail in the following, embodiments disclosed herein implement a new Information Element indicating the required UL response parameters during an information exchange between the participating APs 110, 120. More specifically, as illustrated in figure 4, the AP 110 is configured to transmit a frame 130 to the one or more OBSS APs 120 and / or receive a frame 130 from the one or more OBSS APs 120, wherein the frame 130 comprises an UL Response Parameters Information Element 400. As will be described in more detail further below, the UL Response Parameters Information Element 400 indicates one or more UL Response Parameters for controlling one or more UL responses 235a, b of the one or more non-AP stations 120a-c associated with the respective OBSS AP 120 in response to a DL Data PPDU 233a, b.

[0083] According to standard WLAN technology there are four different options for transmitting an UL response 235a, b to a DL PPDU 233a, b. According to a first option, in case only one user, i.e. non-AP station is allocated for DL transmission (there is only one recipient) and no dedicated signalling of UL response parameters, the station transmits the UL response 235a, b in SU format using the entire BW that includes allocated RU in DL PPDU. For example, if the station receives a 106-tone RU in the DL PPDU 233a, b, it responds with a UL SU PPDU 235a, b transmitted over 20MHz BW. According to a second option, when DL is transmitted in VHTZHE MU format, the first allocated non-AP station should respond with UL SU PPDU similar to the first option, while all the other non-AP stations should wait to be triggered by the AP to transmit UL response (using BAR frame). According to a third option, the AP may indicate an explicit BAR in DL PPDU which means all the allocated non-AP stations should not respond to the DL PPDU until triggered by the AP. In this case the AP may transmit several DL PPDUs and then trigger the non-AP stations to transmit the UL response in a LB PPDU (using MU-BAR PF). According to a fourth option, an implicit HELP ACK policy may be used and a Basic TF for RU allocation of the acknowledgement response of any non-AP station may be added.

[0084] As will be appreciated, given the principles of UL response as defined today in the 802.11 framework of standards, the CoBF scheme is relevant when mutual interference is high or medium so that it may be assumed that mutual interference at UL transmission is also dominant. This implies that UL responses transmitted on the same BW will cause mutual interference so that the resources should be divided among different non-AP stations (i.e. of the sharing AP and the OBSS AP). Furthermore, Block ACK (BACK) frames may be transmitted in response to each CoBF DL PPDU (which carries data frames) or triggered by an explicit MU-Block ACK Request (BAR) after several consecutive CoBF DL PPDUs. Moreover, OBSS APs which use CoBF scheme should negotiate transmission parameters of UL response PPDUs prior to the MAP coordinated transmission.

[0085] The potential mutual interference mandates that different resources are allocated for different non-AP stations 110a, 120a to ensure that the UL response 235a, 235b can be detected by all the APs 110, 120. As will be appreciated, there are three types of resources that can be allocated for this purpose, namely frequency, time and spatial streams. Thus, according to embodiments disclosed herein there may be three different methods to transmit the UL responses 235a, b to the CoBF DL PPDUs 233a, b.

[0086] In an embodiment, a first UL response method may implement concurrent OFDMA based UL responses 235a (as illustrated in figure 3a). In an embodiment, the AP 110, i.e. the sharing AP 110 may allocate a specific portion of the BW to the one or more OBSS APs 120, i.e. to each shared AP 120. The respective shared AP 120 may allocate RUs to its corresponding non-AP stations 120a-c only within this portion.

[0087] In an embodiment, a second UL response method may implement sequential TDMA based UL response 235a (as illustrated in figure 3b). In an embodiment, the AP 110, i.e. the sharing AP 110 may allocate a respective time slot to each of the one or more OBSS APs 120, i.e. the shared APs 120 to complete UL transmission within its BSS.

[0088] In an embodiment, a third UL response method may implement MU-MIMO based UL responses. In an embodiment, the AP 110, i.e. the sharing AP 110 may allocate spatial streams to each of the one or more OBSS APs 120, i.e. the shared APs 120 to transmit in UL MU-MIMO mode.

[0089] As will be appreciated, each of the three different UL response methods described above is associated with different parameters that need to be agreed and indicated to all participating APs. Moreover, APs may also agree and indicate which method will be applied a for specific period of coordination. To address these issues embodiments disclosed herein allow the APs 110, 120 to negotiate, agree and indicate the parameters of the UL responses 235a, b to CoBF DL PPDUs 233a, b. As already mentioned above, this is achieved by means of a new UL Response Parameters Information Element 400 that may be incorporated in any frame 130 exchanged between the AP 110, i.e. the sharing AP 110 and the at least one OBSS AP 120, i.e. the at least one shared AP 120 during either the MAP Coordination Announcement stage 210, the pre-transmission stage 220 or the MAP coordinated transmission stage 230. As will be described in more detail below, according to embodiments disclosed herein the UL Response Parameters Information Element 400 may support any subset of the different UL response methods described above and may also support the option where only a single method is used.

[0090] As already described above, the UL Response Parameters Information Element 400 may be used during the MAP Coordination Announcement stage 210 that is initiated by the sharing AP, where the one or more OBSS APs 120 provide the required UL response parameters to the initiating AP 120, but also, for instance, in the MAP PF 231a, b transmitted by the AP 110, i.e. the sharing AP 110 in the MAP coordinated transmission procedure 230 to indicate the specific UL response parameters to be applied in a response to a current CoBF DL PPDU 233a, b.

[0091] For instance, for the case that the non-AP stations 110a, 120a are configured to provide the UL responses 235a, b according to only one of the UL response methods described above, the UL Response Parameters Information Element 400 may indicate or contain only these parameters relevant for this UL response method.

[0092] Figure 5 shows an embodiment of the UL Response Parameters Information Element 400 for the case that the UL response method implemented by the non-AP stations 110a, 120a is a OFDMA based UL Response transmission. The UL Response Parameters Information Element 400 of figure 5 may comprise at least the following parameters: an explicit BAR indication (not shown in figure 5), a UL Response duration 501, a respective identifier 503a-n of each participating AP 120, a list of BW portions 505a-n allocated for each participating AP 120, and additional parameters 507 that we will be described further below. In an embodiment, the BW portion indication 505a-n may be implemented using RU allocation based on RUs defined by the 802.11 framework of standards.

[0093] Figure 6 shows an embodiment of the UL Response Parameters Information Element 400 for the case that the UL response method implemented by the non-AP stations 110a, 120 is a TDMA based UL Response transmission. The UL Response Parameters Information Element 400 of figure 6 may comprise at least the following parameters: an explicit BAR indication 601, a respective identifier 603a-n of each participating AP 120, and a UL response duration 605a-n per AP 120.

[0094] Figure 7 shows an embodiment of the UL Response Parameters Information Element 400 for the case that the non-AP stations 110a, 120a are configured to provide the UL responses 235a, b according to more than one of the UL response methods described above. In this case the UL Response Parameters Information Element 400 may have a unified design that may support any subset of the methods. To this end, in an embodiment, the UL Response Parameters Information Element 400 illustrated in figure 7 comprises a Control Subfield 701 which provides an indication of a list of the different UL Response methods that are included in the UL Response Parameters Information Element 400 (multiple UL response methods may be indicated for the negotiation stages, while if only one method is indicated it means this method should be applied in the following coordinated transmission). Moreover, the UL Response Parameters Information Element 400 illustrated in figure 7 comprises a list of Method Dependent Subfields 710 (referred to as Method Dependent Info List 710 in figure 7) that may comprise the following subfields for each UL Response method: a Common Subfield 711a-n providing an indication of all the parameters that are common for all the APs 120: and an AP Dependent Info List 713a-n providing a list of indications of the parameters that are relevant for a specific methods and specific AP.

[0095] In an embodiment, the Control Subfield 701 of the UL Response Parameters Information Element 400 may provide the number of indicated UL Response methods and specify which UL Response methods are indicated using one of the following options. According to an embodiment, the Control Subfield 701 of the UL Response Parameters Information Element 400 may contain a bitmap indicative of the number of UL Response methods. In this case the Method Dependent Info List 710 may include an indication of several UL Response methods according to the bitmap provided by the Control Subfield 701. In a further embodiment, the Control Subfield 701 of the UL Response Parameters Information Element 400 may contain a bit code indicating a single selected UL Response method. In this case the Method Dependent Info List 710 may include an indication of a single selected method.

[0096] As already described above, the Method Dependent Info List 710 includes a list of Method Dependent Subfields where each corresponds to a different UL response method, i.e. UL Response method that is applied in the MAP Coordination between two or more OBSS APs. The Method Dependent Info subfield 710 provides an indication of the parameters relevant for a specific UL response method and thus differs between the different UL Response methods described above. The main format of the Method Dependent Subfield 710 comprises the Common Subfield 711a-n and the AP Dependent Subfield 713a-n, as already described above.

[0097] Figure 8 shows an embodiment of the Method Dependent Info subfield 710 for several different possible UL Response methods, including an OFDMA based UL Response transmission. In this embodiment the Common Subfield 711a-n of the Method Dependent Info subfield 710 may comprise or encode an explicit BAR indication 811 , an UL Response duration 813 as well as additional parameters 815. Moreover, for each participating AP 120, the AP Dependent Info subfield of the Method Dependent Info subfield 710 may comprise an AP identifier 803a-n and an indication of the BW portion 805a-n allocated to the respective AP 120. The additional parameters 815 may be provided to make sure that the PHY preambles of the transmitted UL responses are aligned. Those additional parameters 815 may include BSS Color, PHY Version, Spatial Reuse and definition of Disregard and Validate bits.

[0098] Figure 9 shows an embodiment of the Method Dependent Info subfield 710 for several different possible UL Response methods, including a TDMA based UL Response transmission. In the embodiment shown in figure 9 the Common subfield of the Method Dependent Info subfield 710 may comprise an explicit BAR indication 901, and the AP Dependent subfield of the Method Dependent Info subfield 710 may further comprise a respective identifier 903a-n of each participating AP 120, and a UL response duration 905a-n per AP 120 (similar to the embodiment shown in figure 6).

[0099] As already described above, the UL Response Parameters Information Element 400 may be used for negotiations during the Coordination Announcement stage 210, negotiations at the beginning of the TXOP 200 and also for indicating the specific parameters for currently triggered CoBF DL PPDUs. Thus, the UL Response Parameters Information Element 400 may be part of, i.e. included in one or more of the following frames: in the MAP Announcement Request Frame 211 the UL Response Parameters Information Element 400 may indicate the UL parameters that are defined (proposed if negotiation allowed) by the AP 110, i.e. the sharing AP 1 10: in the MAP Announcement Response Frame 213 transmitted by the OBSS AP(s) 120, i.e. the shared AP(s) 120 the UL Response Parameters Information Element 400 may indicate the UL parameters required by the OBSS AP(s) 120, i.e. the shared APs 120: in the MAP TF 231a, b the UL Response Parameters Information Element 400 may indicate the UL parameters that are defined by the AP 110, i.e. the sharing AP 110 for transmitting the UL response 235a, b to the CoBF DL PPDU 233a, b that is triggered by this MAP TF 231 a.b: and / or a Coordination Agreement Request / Response frame.

[0100] Figure 10 shows a flow diagram illustrating a method 1000 according to an embodiment for operating an AP, such as the AP 110 shown in figure 1 , for providing network access to one or more non-AP stations 11 Oa-c associated with the AP 110 and for sharing communication resources of the AP 110 with one or more OBSS APs 120 under a common MAP coordination agreement in a MAP coordinated transmission, when the AP 110 obtains a TXOP 200. The method 1000 comprises a step 1001 of transmitting a frame 130 to the one or more OBSS APs 120 and / or receiving a frame 130 from the one or more OBSS APs 120. As already described above, the frame 130 comprises an UL Response Parameters Information Element 400, wherein the UL Response Parameters Information Element 400 indicates, e.g. contains one or more UL Response Parameters for controlling the UL response of one or more non-AP stations 120a-c associated with the respective OBSS AP 120 for a DL Data PPDU.

[0101] 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).

[0102] 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.

[0103] 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.

[0104] 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) and for sharing communication resources of the AP (110) with one or more overlapping basic service set, OBSS, APs (120) in a Multi-AP, MAP, coordinated transmission under a common MAP coordination agreement, when the AP (110) obtains a transmission opportunity, TXOP (200), wherein the AP (110) is configured to: transmit a frame (130) to the one or more OBSS APs (120) and / or receive a frame (130) from the one or more OBSS APs (120), wherein the frame (130) comprises an UL Response Parameters Information Element (400) and wherein the UL Response Parameters Information Element (400) indicates one or more UL Response Parameters for controlling one or more UL responses of one or more non-AP stations (120a-c) associated with the respective OBSS AP (120) to a DL Data PPDU.

2. The AP (110) of claim 1, wherein the one or more UL responses of the one or more non-AP stations (120a-c) are OFDMA-based UL responses and wherein the UL Response Parameters Information Element (400) comprises an UL Response Duration field (501) indicative of a duration of one or more PPDUs used for the UL response by one or more associated non- AP stations (120a-c) involved in the preceding DL Data PPDUs.

3. The AP (110) of claim 2, wherein for each of the one or more OBSS APs (120) the UL Response Parameters Information Element (400) comprises a Bandwidth, BW, Portion field (505a-n) and wherein each BW Portion field (505a-n) is indicative of a respective BW portion of a transmission BW that is available for the respective OBSS AP (120) for allocation to the one or more associated non-AP stations (120a-c) of the respective OBSS AP (120) for the purpose of the UL response.

4. The AP (110) of claim 3, wherein for each of the one or more OBSS APs (120) the UL Response Parameters Information Element (400) further comprises an AP ID field (503a-n) indicative of the respective OBSS AP (120) corresponding to the respective BW Portion field (505a-n).

5. The AP (110) of claim 1, wherein the one or more UL responses of the one or more non-AP stations (120a-c) are TDMA-based UL responses and wherein for each of the one or more OBSS APs (120) the UL Response Parameters Information Element (400) comprises an UL Response Duration field (605a-n) and wherein each UL Response Duration field (605a-n) is indicative of a total duration of one or more PPDUs used for the UL Response that is available for the respective OBSS AP (120) to receive the one or more UL Responses of the one or more non-AP stations (120a-c) associated with the respective OBSS AP (120).

6. The AP (110) of claim 5, wherein for each of the one or more OBSS APs (120) the UL Response Parameters Information Element (400) further comprises an AP ID field (603a-n) indicative of the respective OBSS AP (120) corresponding to the respective UL Response Duration field (605a-n).

7. The AP (110) of claim 5 or 6, wherein the UL Response Parameters Information Element (140) comprises an Explicit BAR field (601) indicative of one or more of the OBSS APs (120) to use a “Block Ack” ACK Policy in each of their data frames contained in the DL PPDU that are transmitted to their associated non-AP stations (120a-c).

8. The AP (110) of claim 1, wherein each of the one or more non-AP stations (120a-c) associated with each OBSS AP (120) is configured to transmit the UL Response according to a plurality of UL Response methods and wherein the UL Response Parameters Information Element (400) comprises a Control field (701) and a Method Dependent Info List field (710) with a list of a plurality of Method Specific fields, wherein the Control field (701 ) is indicative of one or more of the control parameters and wherein the one or more Method Dependent Info List fields comprises one or more method dependent parameters.

9. The AP (110) of claim 8, wherein the Control field (701) indicates one or more UL Response schemes to be used by the one or more associated non-AP stations (120a-c) of the respective OBSS AP (120).

10. The AP (110) of claim 9, wherein the Control field (701) contains a bitmap or a bit code indicative of the one or more UL Response schemes to be used by the one or more associated non-AP stations (120a-c) of the respective OBSS AP (120).

11. The AP (110) of any one of claims 8 to 10, wherein the Control field (701) comprises an indication of the number of Method Dependent subfields in the Method Dependent Info List field (710).

12. The AP (110) of any one of claims 8 to 11, wherein the one or more fields in the Method Dependent Info List field (710) comprise a Common field (711a-n) containing one or more parameters common for the one or more OBSS APs (120) and for each OBSS AP (120) a Per-AP Info field (713a-n) containing one or more parameters for the respective OBSS AP (120).

13. The AP (110) of any one of claims 8 to 12, wherein the Common field (71 la-n) comprises an Explicit BAR field (811) indicative of one or more of the OBSS APs (120) to use a “Block Ack” ACK Policy in each of their data frames contained in the DL PPDU that are transmitted to their associated non-AP stations (120a-c).

14. The AP (110) of any one of claims 8 to 13, wherein for the case of OFDMA-based UL Response scheme, the Common field (71 la-n) comprises an UL Response Duration subfield (813) indicative of a duration of the one or more PPDUs used for a UL response by the one or more associated non-AP stations (120a-c) involved in the preceding DL Data PPDU.

15. The AP (110) of claim 14, wherein the AP Dependent Info field (713a-n) for each of the one or more OBSS APs (120) comprises a Bandwidth, BW, Portion subfield (805a-n) and wherein each BW Portion subfield (805a-n) is indicative of a respective BW portion of a transmission BW that is available for the respective OBSS AP (120) for allocation to the one or more associated non-AP stations (120a-c) of the respective OBSS AP (120) for the purpose of the UL response.

16. The AP (110) of claim 15, wherein for each of the one or more OBSS APs (120) the AP Dependent Info field (713a-n) further comprises an AP ID subfield (803a-n) indicative of the OBSS AP (120) corresponding to the respective BW Portion subfield.

17. The AP (110) of any one of claims 8 to 16, wherein the one or more UL responses of the one or more non-AP stations (120a-c) are one or more TDMA based UL responses, wherein for each of the one or more OBSS APs (120) the Per AP Info field (713a-n) comprises a UL Response Duration subfield (905a-n) and wherein each UL Response Duration subfield (905a- n) is indicative of a total duration of the UL Response that is allocated for the respective OBSS AP (120) to receive the one or more UL Responses of the one or more non-AP stations (120a-c) associated with the respective OBSS AP (120).

18. The AP (110) of claim 17, wherein for each of the one or more OBSS APs (120) the Per Info field (713a-n) further comprises an AP ID subfield (903a-n) indicative of the respective OBSS AP (120) corresponding to the respective UL Response Duration subfield (905a-n).

19. The AP (110) of any one of the preceding claims, wherein the AP (110) is configured to include the UL Response Parameters Information Element (400) within a transmitted frame (130) to the one or more OBSS APs (120).

20. The AP (110) of claim 19, wherein the transmitted frame (130) is a MAP Announcement Request Frame (211) or a MAP Coordination Agreement setting Request frame.

21. The AP (110) of any one of claims 1 to 18, wherein the AP (110) is configured to include the UL Response Parameters Information Element (400) within a transmitted frame (130) when it is shared in a TXOP (200) by a sharing AP.

22. The AP (110) of claim 21, wherein the transmitted frame (130) is a MAP Announcement Response Frame (213) or a MAP Coordination Agreement setting Response frame.

23. The AP (110) of any one of claims 1 to 18, wherein the AP (110) is configured to include the UL Response ParametersInformation Element (400) within a transmitted frame (130) to the one or more OBSS APs (120) and wherein the frame (130) is a MAP Trigger Frame, TF, (221, 231a, b).

24. A method (1000) 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) and for sharing communication resources of the AP (110) with one or more overlapping basic service set, OBSS, APs (120) under a common Multi-AP, MAP, coordination agreement in a MAP coordinated transmission, when the AP (110) obtains a transmission opportunity, TXOP (200), wherein the method (1000) comprises: transmitting (1001) a frame (130) to the one or more OBSS APs (120) and / or receiving a frame (130) from the one or more OBSS APs (120), wherein the frame (130) comprises an UL Response Parameters Information Element (400) and wherein the UL Response Parameters Information Element (400) indicates one or more UL Response Parameters for controlling the UL response of one or more non-AP stations (120a-c) associated with the respective OBSS AP (120) for a DL Data PPDU.

25. 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 (1000) of claim 24, when the program code is executed by the computer or the processor.14

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