Access points, stations, and corresponding methods

Abstract

A method is proposed by which an access point can identify and trigger stations with strict delay requirements or with periodic traffic to be transmitted to their corresponding access point simultaneously with uplink traffic from its own service set. The existing spatial multiplexing is improved to take into account the receive beamforming capabilities at the access point. In addition, a method is proposed to collect channel information in an efficient manner and enhance the triggering process to allow stations from overlapping cells to access the channel during transmit opportunities or resource units allocated to other users.

Description

Technical Field

[0001] The present disclosure relates to various access points, stations, and corresponding methods. Background Art

[0002] Low-latency or real-time applications have strict requirements for fast or periodic channel access. For example, these requirements are relatively easy to achieve within a WLAN basic service set (BSS; also referred to as a cell hereinafter) where one or more stations (STAs) are associated with one access point (AP) serving one or more STAs. However, this is no longer the case when a STA is within the range of multiple overlapping BSSs (OBSSs) managed by different APs, and one or more other STAs are associated with these overlapping BSSs in corresponding other BSSs. Then, one or more other STAs (also referred to as overlapping STAs (oSTAs)) associated with another AP serving another BSS are within the range of the AP serving one or more STAs.

[0003] Spatial Reuse (SR) techniques are defined in the upcoming 802.11ax amendment to the IEEE 802.11 standard. These allow oSTAs from overlapping BSSs to transmit during time intervals scheduled by the AP, as long as the interference at the AP can be guaranteed to be below a tolerable level.

[0004] The "background technology" description provided herein is for the purpose of generally presenting the context of the present disclosure. To the extent described in this background technology section, the work of the presently named inventors and aspects of the description that may not be considered prior art at the time of filing are neither explicitly nor implicitly admitted to be prior art against the present disclosure. Summary of the invention

[0005] One object is to provide an access point and a station capable of enhancing uplink spatial multiplexing. Another object is to provide a corresponding method and a corresponding computer program and a non-transitory computer-readable recording medium for implementing the method.

[0006] According to one aspect, there is provided a first access point, the first access point comprising a circuit configured to:

[0007] - communicating with one or more first stations associated with the first access point;

[0008] - sending a trigger requesting the station to send a data unit containing a channel estimation sequence and / or channel feedback information enabling channel estimation;

[0009] - determining channel information based on channel estimation sequences and / or channel feedback information sent from one or more of said first stations and from one or more second stations associated with a second access point; and

[0010] -Determine spatial multiplexing parameters based on the determined channel information for the first access point to use for receiving data during the period in which one or more of the second stations spatially multiplex resources allocated to one or more of the first stations, the first stations being used to send data to the first access point, and the second stations being used to send data to the second access point.

[0011] According to another aspect, there is provided a station comprising circuitry configured to:

[0012] - communicating with an associated second access point;

[0013] - receiving a trigger from a first access point associated with one or more first stations, the trigger requesting the station to send a data unit containing a channel estimation sequence and / or channel feedback information enabling channel estimation;

[0014] -sending a channel estimation sequence and / or channel feedback information enabling channel estimation to the first access point;

[0015] - receiving an individual transmit power level or an individual transmit power limit from the second access point or the first access point;

[0016] - receiving resource allocation information from the first access point indicating resource units allocated to the second station for spatial multiplexing; and

[0017] - during spatial multiplexing of resources allocated by the first access point to one or more of the first stations, sending data using the allocated resource units and a received individual transmit power level or a transmit power level equal to or lower than a received individual transmit power limit, the first stations being used to send data to the first access point.

[0018] According to another aspect, there is provided a second access point comprising circuitry configured to:

[0019] - communicating with one or more second stations associated with the second access point;

[0020] - receiving a trigger from the first access point to start estimating a channel between the second access point and one or more first stations and / or one or more second stations associated with the first access point;

[0021] - determining channel information based on data units sent from one or more of said first stations and one or more of said second stations, said data units comprising a channel estimation sequence and / or channel feedback information enabling channel estimation;

[0022] - identifying one or more second stations using resource units allocated by the first access point for spatial multiplexing and / or random access; and

[0023] - Sending identification information to the first access point, the identification information indicating that spatial multiplexing is possible and / or considered for one or more second stations.

[0024] According to another aspect, there is provided a first access point comprising circuitry configured to:

[0025] - communicating with one or more first stations associated with the first access point; and

[0026] - notifying one or more second stations associated with the second access point that the one or more second stations are allowed to transmit data to the associated second access point during spatial multiplexing of resources allocated to the one or more first stations for transmitting data to the first access point.

[0027] According to another aspect of the corresponding method, a computer program and a non-transitory computer-readable recording medium are provided, wherein the computer program includes a program device for causing the computer to perform the steps of the method disclosed in this document when the computer program is executed on the computer, and the non-transitory computer-readable recording medium stores a computer program product, which, when executed by a processor, causes the method disclosed in this document to be executed.

[0028] Embodiments are defined in the dependent claims. It should be understood that the disclosed station, the disclosed method, the disclosed computer program and the disclosed computer readable recording medium have other embodiments similar and / or identical to the claimed access point and as defined in the dependent claims and / or disclosed herein.

[0029] One aspect of the present disclosure is to enable STAs with strict delay requirements or with periodic services to access uplink resource units (RUs) in another BSS other than their own. Another aspect may be to collect channel information from STAs in an efficient manner in order to find uplink (UL) beamforming parameters (i.e., beamforming vectors) for the AP to receive during the spatial multiplexing phase, where one or more STAs associated with the AP and one or more oSTAs associated with another AP of the OBB can share the same frequency and / or time resources for transmission. In addition, in an embodiment, a triggering process is provided to allow STAs from overlapping cells to access the channel during transmission opportunities or resource units allocated to other STAs. The existing spatial multiplexing concept can be further improved to take into account the receive beamforming capabilities at the AP.

[0030] The foregoing paragraphs are provided by way of general introduction and are not intended to limit the scope of the appended claims.The described embodiments, together with other advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] A more complete appreciation of the present disclosure and many of its attendant advantages will be readily obtained as the present disclosure becomes better understood by referring to the following detailed description when considered in conjunction with the accompanying drawings, in which:

[0032] Figure 1 A diagram showing a trigger frame according to IEEE P802.11ax D4.0 including UL SR information is shown.

[0033] Figure 2 A schematic diagram of an exemplary embodiment of a communication system according to the present disclosure is shown.

[0034] Figure 3 A schematic diagram illustrating an embodiment of enhanced sounding for obtaining sounding information from a STA and obtaining sounding or identification information from an oSTA is shown.

[0035] Figure 4A A trigger-based PPDU structure is shown as a response to a beamforming trigger frame for feedback and identification.

[0036] Figure 4B A more general form of a trigger-based PPDU is shown.

[0037] Figure 5 A schematic diagram illustrating another embodiment of enhancing detection when the oSTA is known is shown.

[0038] Fig. 6A A flow chart illustrating an embodiment of a process of a first AP is shown.

[0039] Figure 6B A flow chart illustrating an embodiment of a process for a second AP is shown.

[0040] Figure 7 A schematic diagram illustrating another embodiment of enhanced sounding with UL return-to-null information collection is shown.

[0041] Figure 8 A schematic diagram illustrating yet another embodiment of enhanced detection is shown.

[0042] Fig. 9 A flow chart illustrating a method used by a first access point is shown.

[0043] Fig.10 A flow chart showing the method used by the second station is shown.

[0044] Fig.11 A flow chart showing a method used by a second access point is shown. DETAILED DESCRIPTION

[0045] Figure 1A diagram of a trigger frame according to IEEE P802.11ax D4.0 including UL SR information is shown. The UL SR scheme was designed in IEEE P802.11ax D4.0 based on the assumption that the AP has no information about the STAs that can utilize the SR RU. In this context, the tolerable interference limit is set so that for all STAs that are specifically addressed to use the RU, certain QoS (Quality of Service) metrics are met, such as a minimum SNR or a PER below a threshold, while non-addressed STAs can access if they comply with the SR conditions. This behavior can be very limiting, especially in scenarios where STAs with worst-case SNRs are well spatially separated from STAs that want to transmit to their own AP in a spatially multiplexed manner using the same frequency slots. In the context of coordinated nulling, most schemes focus on the downlink and require relatively good synchronization between the APs involved in the nulling process.

[0046] In this context, the STA that requires nulling (further referred to as a STA from an overlapping BSS or overlapping STA (oSTA)) is a STA that should minimize interference (e.g., with the help of beamforming design). In the present disclosure, an oSTA is a STA from an overlapping BSS that, when transmitting to its corresponding access point, transmits to its own access point in the same time and frequency resources used by another STA. In the present disclosure, the latter access point is referred to as a master access point (or first access point), which allocates resources to its own STA (first station) and determines whether spatial multiplexing of these resources with the oSTA (second station) is possible. For this purpose, the master AP can design and apply receive beamforming vectors to minimize interference from the oSTA while ensuring acceptable reception quality from its own STA. The AP with which the oSTA communicates will be referred to as an overlapping AP (oAP) (or second access point). In some scenarios, coordination between the AP and the oAP is necessary to ensure proper multiplexing of resources. In these cases, it is assumed that the AP plays the role of the master AP and the oAP plays the role of the slave AP, which performs the estimation and provides the required feedback to the master AP.

[0047] The purpose of the present disclosure is to propose a mechanism that allows oSTA to access the uplink resource units of STAs in other BSSs outside of itself (for example, there are strict or periodic business requirements). To this end, the receive beamforming scheme at the AP or master AP can be designed to eliminate interference from the oSTA during the RU of uplink transmission allocated to the STA associated with the corresponding AP. When such a receive beamforming scheme is feasible, the oSTA and the STA associated with the AP can be allowed to share the RU. In addition, an enhanced spatial multiplexing standard based on the receive beamforming capability at the AP involved, and a protocol flow that allows its implementation are proposed. An embodiment is configured to effectively identify oSTAs that require UL SR and collect channel information of both STAs and oSTAs with reduced overhead.

[0048] The following description focuses on uplink nulling for several reasons. First, due to the difference in transmit power, it is more feasible to implement nulling in the uplink than in the downlink. Second, since non-AP STAs have fewer streams to transmit simultaneously, there may be more degrees of freedom available at the AP in the UL than in the DL. For example, in a multi-user (MU) MIMO scenario, multiple streams for all STAs can be sent in the DL on the same resource unit, while in the uplink STAs respond in separate resource units. Figure 2 This scene is depicted in Figure 2 A schematic diagram of an exemplary embodiment of a communication system that can use UL SR according to the present disclosure is shown. Here, arrows 10 and 11 represent UL transmission of useful signals using RU set 1, arrows 12 and 13 represent UL transmission of useful signals using RU set 2, arrow 14 represents interference using RU set 1, and arrow 15 represents interference using RU set 2.

[0049] The communication system includes: a first access point AP1 (which can assume the role of a master access point and is referred to as a master access point), a plurality of first stations STA1 to STA N are associated with the first access point AP1; and two second access points oAP1 and oAP2, each having associated second stations oSTA1 and oSTA2 from an overlapping BSS (oBSS), respectively. The goal is to design a receive beamformer at the AP (AP1, oAP1, and oAP2) so that the first station and the second station can simultaneously transmit to their respective access points, the first station and the second station are associated with the respective access points, and are correctly received with an acceptable quality of service. According to the present disclosure, in the UL, each RU can typically have one or more STAs, so that the AP can have sufficient degrees of freedom to design a receive beamforming vector that eliminates interference from a specific oSTA.

[0050] The synchronization requirements to achieve uplink nulling are significantly reduced compared to the DL scheme, especially for joint transmission. For the scheme proposed in this paper, the main requirement is that each participating AP is able to listen to multiple STAs simultaneously and calculate a separate spatial multiplexing criterion. In another scenario included in this paper, a certain degree of coordination between AP and oAP is required, as information about oSTAs and spatial multiplexing feasibility and parameters is exchanged between the access points involved. However, in both cases, the requirements for synchronization and coordination are less stringent than for the current coordinated downlink nulling.

[0051] The following situations, from most specific to most general, are dealt with below:

[0052] 1. Information about an oSTA that may need to transmit simultaneously with one or more STAs is available at the master AP. For example, this scenario is relevant to an oSTA that needs to send periodic traffic / control information or updates, such as a Virtual Reality (VR) set sending control information. In this case, the oSTA will be referred to as a "known" oSTA.

[0053] 2. Only information about a group of oSTAs is available at the AP, from which one oSTA may be allowed to transmit in a spatially multiplexed manner based on buffering conditions / priority information / contention rules, but there is no individual information about a specific oSTA. This is relevant, for example, within a low-latency Industrial Internet of Things (IOT) scenario, where many devices may need to send updates.

[0054] 3. There is no information at the AP about whether there is an oSTA that may need to transmit in a spatially multiplexed manner. In cases 2 and 3, the oSTA will be referred to as an "unknown" oSTA.

[0055] In all three cases, a spatial multiplexing criterion is defined that relies on the fact that channel state information (CSI) is available at the AP. The three cases differ in the method of handling oSTAs and collecting the associated CSI, as well as in the reasonable training overhead.

[0056] First, a beamforming method based on UL SR will be described. Unlike current SR schemes, the AP does not calculate an overall interference limit, but calculates a single interference limit based on its beamforming capabilities and the quality of service (QoS) constraints required by its STAs. In order to allow oSTA to be sent simultaneously during the transmission of its own STAi within RUi, the AP should be able to design its receive beamformer so that in the presence of interference from oSTA, it is guaranteed to receive STAi with the required SINR. To this end, channel estimates for both STAi and oSTA should be available at the AP.

[0057] In more detail, in order for the first AP to be able to decode the message from its own STA in the presence of interference from oSTA1, the first AP should be able to design the receive beamforming vector u1 such that the signal to interference plus noise condition is satisfied:

[0058]

[0059] Among them, R1 (1) , R2 (1) are the channel covariance matrices from STA1 and oSTA1 to AP1, q1 and q2 are the transmit power levels of STA1 and oSTA1, σ1 2 is the noise variance, and γ1 is the SINR threshold.

[0060] Meanwhile, in order for oAP1 to be able to decode the message from oSTA1, oAP1 should meet similar conditions, that is, oAP1 should be able to design the receive beamforming vector u2 such that some SINR conditions are met:

[0061]

[0062] Among them, R1 (2) , R2 (2) are the channel covariance matrices from STA1 and oSTA1 to AP2, and σ2 2 and γ2 represent the noise variance and SINR threshold of reasonable bit error rate at AP2, respectively.

[0063] For OFDM schemes, the conditions in (1) and (2) are defined per subcarrier or subcarrier group. In addition, the STA and oSTA on which these conditions are tested have been trained on the same bandwidth, part of the bandwidth, or resource units. Further preselection based on the strength of correlation between the STA and the oSTA and the service requirements of the STA can be used to identify the pairs of conditions to be checked.

[0064] It can be noted from (1) and (2) that, due to the reliance on beamforming capabilities and channel information, only the AP can calculate the SR conditions, available only to themselves. In the current sounding and BF triggering scheme defined in IEEE802.11, only CSI from STAs directly served by the AP can be collected (not from oSTA). However, the optimal u1 cannot be calculated using only the feedback from STA1. The AP can calculate a suboptimal u1 that matches the channel of STA1, and then use this u1 in subsequent stages to allow oSTA to decide whether these can comply with the currently defined SR conditions. However, this scheme may have disadvantages: first, the u1 beamforming vector is suboptimal because interference is not considered at all. Second, it means that there is a separate training step for oSTA.

[0065] If the AP uses the same beamforming weight u1 to transmit to and receive from STA1, then a method similar to that currently used for SR can be defined. However, it is not always useful or necessary to employ the same BF in DL and UL (e.g., in the MU case, where the DL BF is used to send streams to various users, while the responses are on separate RUs in the uplink).

[0066] If u1 comes from a predefined dictionary, the existing SR method can be used again, in which the various defined beamforming sequences are modulation estimation sequences, and the involved STAs and oSTAs can calculate for themselves whether the interference limit can be observed. However, in this case, the problem becomes that combining and detection may take a long time.

[0067] The disclosed method is based on directly estimating the channel information R1 (1) , R2 (1) 、R1 (2) , R2 (2) Based on this information, the feasibility of spatial multiplexing for specific combinations of STAs and oSTAs is determined, as well as the power requirements to be met by these combinations.

[0068] For fixed q1 and q2, the beamforming vectors in (1) and (2) can be easily found by solving the generalized eigenvector problem. To handle the uplink power, several approaches can be thought of. In one embodiment, it is proposed to consider the uplink power of the RU holder (i.e., q1 in this example) as fixed and define a maximum acceptable limit for q2. At AP2, for a fixed q1, the feasibility problem is solved, based on which AP2 decides whether it can decode the signal from oSTA1 at the indicated q1 level. In the case of infeasibility, AP2 can make a recommendation to AP1 about the maximum q1 below the indicated threshold, which allows acceptable transmission from oSTA1 to oAP1. Finally, AP1 indicates the acceptable levels of q1 and q2 to STA1 and oSTA1, respectively.

[0069] In this context, determining the beamforming vectors by solving the generalized eigenvector problem means that in order to find the beamforming vectors that satisfy the criteria (1) and (2), a generalized eigenvalue decomposition of a particular matrix with the first criterion and the second criterion can be performed (see below for Fig. 6A and Figure 6B The largest eigenvector can then be used as the optimal receive beamforming vector.

[0070] SR feasibility means that there are beamforming vectors that can comply with the SINR criteria for certain power levels. One option to indicate that SR is not feasible is by setting the recommended power level to 0 and indicating feasibility by setting the power to a positive value. However, more explicit indications may also be found.

[0071] In order to implement a protocol based on the above approach, modifications to the current SR and probing procedures are proposed. These are explained below.

[0072] In one embodiment, a probe is applied to collect CSI from STAs and oSTAs. Currently, only STAs within a BSS can be triggered to send feedback information as part of the probe phase. Therefore, it is not possible to obtain probe information from an oSTA using current procedures. Secondly, in order to keep the overhead reasonable, CSI should only be collected from oSTAs with strict business requirements. However, the AP may not always know which are these STAs, or whether there are indeed oSTAs that need to be sent to their corresponding oAPs. Therefore, it is desirable to define / enhance the probe protocol to allow UL channel information from two STAs to be served by the AP (direct trigger) and probe and identification information from the oSTA to be collected with low overhead. The latter can be triggered directly, if known, for example, in the case of certain periodic allocations known between neighboring APs, or indirectly by allowing the RU range for random access.

[0073] A method that allows for simultaneous collection of feedback information from STAs and identification or detection from oSTAs is based on an enhanced DL detection process. Figure 3 This method is depicted in FIG4 , which will be explained in more detail below. When the identification information of the oSTA that needs to access the channel in SR mode is already available, an alternative method for this situation is depicted in FIG4 . When the oSTA has only one UL stream, Figure 3 The method shown in Figure 4 is most suitable. When the oSTA has multiple streams, this method can be applicable when a priori information about the number of streams to be used in the UL is available at the AP. The latter can then include the information in a modified null data packet (NDP) announcement. Based on this, the STA can select appropriate transmission parameters in a trigger-based (TB) physical protocol data unit (PPDU), so that the data packet can be correctly decoded at the AP.

[0074] In an alternative approach for multiple streams UL, an uplink sounding procedure is performed to allow the AP to estimate channel information based on the number of UL streams to be used by the STA. Figure 7 How to modify the uplink probe to allow collecting information about the oSTA is shown in FIG. 5 , which will be explained in more detail below.

[0075] Additionally, some enhanced acknowledgements are defined which may be used in one embodiment to inform oSTAs that they may use SR slots.

[0076] In another embodiment, identification of relevant oSTAs is applied, which can transmit in spatial multiplexing mode and have information to transmit.

[0077] According to one method, a protocol is defined, based on which feedback information from STAs and identification or detection information from oSTAs are collected simultaneously. More specifically, it is proposed to modify the detection process so that part of the resources are allocated to the STA that sends feedback, while the remaining resources can only be accessed by oSTA under predetermined conditions: for example, when the mapping of resource units to BSSs and AID sets to pilot sets is known at the APs involved in the scheme and supported by the standard, only oSTAs from coordinated clusters or only oSTAs with urgent business needs can respond or the behavior is allowed. In this case, identification information from oSTAs will be collected during the feedback phase of the STA, and CSI information can be obtained in the second phase. In order to implement this method, several existing frames can be modified, namely the Beamforming Report Poll (BFRP) trigger frame and the Trigger-Based (TB) PPDU containing feedback from various STAs.

[0078] Another approach is based on NDP Feedback Reports (NFRP) and TB NDP PPDUs. It works as follows. For each of a set of neighboring (and coordinated) APs, a set of AID ranges and a set of pilot patterns corresponding to each AID are defined. This can be determined by the master AP in a multi-AP scenario, for example. Based on these AID ranges, if the oSTA has information to send and needs to do so in overlapping transmissions, they send it with a pilot pattern that corresponds to the AID range of the AP it needs to send to. Based on the information collected in this way, it can be used Figure 5 The process described in obtains detection feedback from both STA and oSTA.

[0079] In another embodiment, the application triggers the UL transmission from the STA to the AP and the oSTA to the corresponding oAP. The trigger frame should be designed to address the oSTA and inform the oSTA's expected transmission time to its corresponding oAP. In addition, the oSTA should be able to decode the RU allocation information in the trigger frame. Only the specifically addressed oSTA regarding the power control condition can be sent to the AP that is not the transmitter of the trigger frame.

[0080] Figure 3A schematic diagram illustrating enhanced sounding for obtaining sounding information from STAs and sounding or identification information from oSTAs is shown. In a first step, an NDP notification is sent by the master AP (AP1 in this case) to allow the STAs to be served by the master AP, as well as the oSTAs and their corresponding APs, to know the start of the channel sounding interval. NDP is a PHY packet that contains enough channel estimation sequences to allow all STAs to estimate the channel information of all streams to be used. Subsequently, a trigger is sent, and the requesting station sends a data unit containing a channel estimation sequence and / or channel feedback information that enables channel estimation. In a specific embodiment, a packet called a BFRP trigger is sent, which serves to trigger the STA to send the estimated channel information. In order to collect information not only from STAs but also from potential oSTAs, it is proposed in an embodiment to define a BFRP trigger with a resource allocation, which includes a first set of resource units reserved for STAs served by the AP, which initiates the sounding phase. Therefore, the STA and the oSTA receive a trigger from the master AP, and in response to the trigger, the STA and the oSTA send a channel estimation sequence and / or channel feedback information that enables channel estimation to the AP.

[0081] In one embodiment, the remaining resource units can be allocated as follows. If the AP knows the exact oSTA that needs to be zeroed, these will be triggered directly. For this purpose, a combination of AID and BSS color (i.e., identifier of the BSS) can be used. The destination of the frame within the trigger can also be set so that the corresponding APS / BSS and the AP that triggered the detection process are notified that they should process the response frame and estimate the channel and extract the identification information based on the response frame.

[0082] If the AP does not know the oSTA that needs to be nulled, but knows a potential set of oSTAs that can access the channel, the trigger frame can contain a set of AIDs (and BSS identifiers) corresponding to these oSTAs and RUs in which the STAs corresponding to these AIDs can respond. Upon receipt, the oSTA with information to send will respond with a pilot pattern corresponding to its AID within the RU of the allocated TB-PPDU. This is done in Figure 4A Depicted in Figure 4A The TB PPDU structure is shown as a response to the BFRP frame for feedback and identification, where, for simplicity, only one STA is assigned to respond to the AP on RU1, while RU2 is assigned to the valid oSTA (belonging to an overlapping BSS and whose identifier has been signaled in the BFRP trigger). STA1 replies with the requested channel feedback information in the required format within its dedicated RU. Each oSTA replies within RU2, but using a different pilot pattern.

[0083] Once received, the AP detects oSTA activity on RU2 and thus knows that it should obtain channel and transmission information from the oSTA to decide if it can be nulled and which parameters to use. In addition, thanks to the different pilot structure, the AP can identify the AID of the oSTA. Therefore, it has the necessary information to trigger the oSTA specifically and therefore request them to send data units that allow channel estimation. The triggering of the oSTA occurs in a subsequent stage, which includes the step of triggering the detected oSTA to send an NDP packet on a specific frequency resource, based on which AP1 and oAP1 estimate the uplink channel and determine the necessity and feasibility of spatial multiplexing.

[0084] Therefore, the master AP can determine the channel information based on the channel estimation sequence and / or channel feedback information sent from one or more of the STAs and from one or more of the oSTAs. Optionally, the master AP can identify whether there is a second station that expects to use spatial multiplexing by receiving a channel estimation sequence and identification information from the second station or a channel estimation sequence sent with a pilot pattern, the pilot pattern corresponding to an identifier known to the first access point to which it needs to send data. The identification information can be sent by the oSTA at the same time as the channel feedback information from the first STA.

[0085] In addition, the master AP can determine spatial multiplexing parameters based on the determined channel information for the first access point to use for receiving data during the period when one or more of the second stations spatially reuse resources allocated to one or more of the first stations, the first station is used to send data to the first access point, and the second station is used to send data to the second access point. In an embodiment, the master AP can determine whether and for which one or more stations (e.g., among the stations that respond to the trigger) spatial multiplexing is possible, and with which parameters spatial multiplexing is possible. Information for determining whether SR is possible can rely on earlier information (e.g., a previous trigger) or not.

[0086] The second access point mainly provides identification information to let the master AP know which oSTAs may need to access the channel in SR mode, for example, due to low-latency service requirements. SR feasibility can be reported to the master AP, but can also be sent directly to the second station. One option is that the second access point sends SR parameters directly to the identified second station in the form of power limits. Then, the second stations can decide whether they can send in SR mode based on the power limits received from the master access point and the second access point, rather than sending SR feasibility and parameters directly to the master access point.

[0087] In addition, a confirmation about the feasibility of uplink spatial multiplexing and the updated power level to be used is sent in a modified Ack frame. If no activity is detected on RUs other than RU1, the AP only sends a confirmation to the STA that the feedback information has been correctly received, and this ends the probing process without the need for additional air time reservation. Depending on the RUs used, the BSS can be identified.

[0088] Figure 4B A more general form of the TB PPDU is shown. Within a group of RUs, only oSTAs from one BSS should be allowed to facilitate detection. Within each RU, multiple oSTAs may reply with a pilot pattern, such as Figure 4A Based on the pilot pattern and RU, the master AP can identify which oSTA of which BSS needs channel access or uplink transmission within a certain time interval, and decide whether spatial multiplexing may be required or whether spatial multiplexing is feasible.

[0089] If the AP does not have any information about the oSTA that needs to be zeroed, it can announce random resources within the available resource units. The oSTA that needs to be zeroed (and is within the AP's coordination set) can respond according to the contention rules. Optionally, a set of staggered pilot sets or patterns can be defined, each corresponding to a possible AID. The STA that needs to be zeroed randomly selects a pilot pattern and uses it when responding within the resource unit. If the AP detects activity on one or more random resource units, it will have a separate trigger frame after the TB PPDU to explicitly collect more information about the STA. Otherwise, it will confirm the receipt of feedback from its own STA and terminate the detection process.

[0090] If oSTA is known, then Figure 5 The design shown is better than the above reference Figure 3 A more efficient approach is explained in the example above. In this case, both STA1 and oSTA1 send TB PPDUs over the entire bandwidth or over a desired portion of the bandwidth, i.e., within resource units with the same time and frequency parameters for both STA1 and oSTA1 but with orthogonal channel estimation sequences. Due to their orthogonality, the channel estimation sequence from STA1 R1 can be estimated. (1) 、R1 (2) and oSTA1 R2 (1) , R2 (2)channel. Finally, STA1 appends its DL feedback to the packet. oSTA1 does not send more data, but only filler information. In addition, an enhanced Ack is depicted, which is defined to address both STA1 and oSTA1 and inform them of the feasibility of spatial multiplexing in the uplink and / or the updated power information to be used during uplink transmission. The feasibility can be implicitly defined by the power information, for example, the power information of oSTA1 being 0 will implicitly indicate the unfeasibility of spatial multiplexing.

[0091] Using the SR standard description provided above and Figure 5 The frame and protocol description provided in , the processing steps at AP1 and oAP1 after receiving the TB PPDU are summarized in Fig. 6A (for AP1) and Figure 6B (For oAP1) in the flowchart shown.

[0092] In the first step S10 of the processing of AP1, based on P1×N×LTF, q1R1 (1) Decode and q2R2 based on P2×N×LTF (1) In these representations, LTF represents a common estimation unit for one stream or RF chain, N×LTF is N repetitions that allow performing estimations from multiple RF chains, and P1 and P2 represent matrices to ensure the orthogonality of the estimation sequences in order to distinguish the various RF chains from the users participating in the transmission. In the second step S11, (q1R1 (1) ,q2R2 (1) +σ1 2 I), where I represents an identity matrix of appropriate dimension. In the third step S12, it is checked whether the above condition (1) is satisfied.

[0093] If the conditions in (1) at AP1 are not met for the adopted transmit power, a parameter adaptation function is calculated in step S13. An example of parameter adaptation at AP1 is to calculate the maximum q2 that satisfies the conditions in (1) for a fixed q1, or to calculate the maximum q2 that satisfies the conditions in (1) with a new target, taking into account a lower MCS target γ1. In step S14, an enhanced Ack with modified TxP / MCS parameters is assembled and then sent. If the conditions in (1) at AP1 are met for the adopted transmit power, an enhanced Ack is sent to the STA and oSTA in step S15. The Ack is called "enhanced" because it simultaneously addresses STAs from overlapping cells that are directly associated with the AP as well as the oSTA. In addition, parameters related to spatial multiplexing (such as separate transmit power and / or transmit power limits, which STAs and oSTAs will share resources, and which resource units will be shared) are not supported by existing Ack frames, but should be supported for the scheme disclosed in this article. For these reasons, the Ack is treated as an enhanced Ack.

[0094] Therefore, the STA and the oSTA may receive individual transmit power levels or individual transmit power limits from the AP1 or the oPA1. In addition, they may receive resource allocation information from the AP1 indicating resource units allocated for spatial multiplexing, so that the oSTA may transmit data using the allocated resource units and the received individual transmit power levels or a transmit power level equal to or lower than the received individual transmit power limit during spatial multiplexing of the resources allocated by the AP1 to one or more of the STAs, so as to transmit data to the AP1.

[0095] about Figure 6B In the process at oAP1 described in the above, after receiving a trigger from AP1 to start estimating the channel between oAP1 and one or more STAs associated with AP1 and / or one or more oSTAs, in a first step S20, based on P1×N×LTF, q1R1 (2) Decode and q2R2 based on P2×N×LTF (2) In the second step S21, calculate (q1R1 (2) ,q2R2 (2) +σ2 2 In the third step S22, it is checked whether the above condition (2) is satisfied.

[0096] If the conditions in (2) at oAP1 are not met for the adopted transmit power, a recommendation is calculated in step S23. Examples of some parameter recommendations at oAP1 are as follows. For a fixed q1, the maximum tolerance limit γ that meets the conditions in (2) is calculated2，cc Alternatively, calculating SR is possible q1 recommendation. Another option is to determine a power recommendation for oSTA1, for example in the form of the amount of power that should be reduced or increased in oSTA2's transmissions in order to meet criterion (2). In step S24, the above adjustment parameters (q1), Δq 2，acc , γ 2，cc If the adopted transmission power satisfies the condition in (2) at oAP1, then step S24 is directly executed.

[0097] Therefore, oAP1 can determine channel information based on a data unit sent from one or more of the STA and oSTA, the data unit containing a channel estimation sequence and / or channel feedback information that enables channel estimation. In addition, oAP1 can identify one or more oSTAs using resource units allocated to spatial multiplexing and / or random access performed by AP1, and send identification information to AP1, the identification information indicating whether and / or for which one or more oSTAs spatial multiplexing is possible or considered.

[0098] As mentioned above, AP1 requires input from oAP1, which should include a list of identifiers of oSTAs that may need to be considered during SR training and SR operation, as well as optional spatial multiplexing parameters, feasibility, and power recommendations. The input from oAP1 can be within the wired backhaul, or within the wireless backhaul. In the latter case, AP1 sends a trigger to the oAP to obtain a list of parameters whose oSTAs are participating in SR training.

[0099] In another embodiment, as with the above reference Figure 3 and Figure 5 Unlike the illustrated embodiment, by using a modified version of the NDP feedback report, oSTAs that have information to send and may need to be zeroed can be identified in a dedicated phase of the probe independent of STA feedback. Initially, the NDP feedback report has been defined to collect information about STAs within the BSS that have information in their queues and need to be triggered. However, this can be modified to allow the AP to collect information about oSTAs that need overlapping transmissions. To this end, the NFRP trigger can be modified to include multiple AID sets of STAs associated with neighboring APs: AID set 1 for oAP1, AID set 2 for oAP2. For each AID, a pilot pattern is defined for use in the following TB NDP feedback. The addressing of the NFRP trigger can also be modified to enable the oAP to identify itself as a receiver and synchronize its reception with the transmission of subsequent TBNDPs from the oSTA. After identifying the STAs that need UL zeroing, these STAs can be specifically triggered to obtain channel information during the NDP probe as described above or in a separate phase.

[0100] An embodiment using multiple stream operations will be described below. In this embodiment, the following scenario should be considered: only one STA with SU-MIMO capability and an AP with a number of antennas greater than the number of antennas at the STA. In this case, the AP can use the additional degrees of freedom to allow the oSTA to access the same RU as the STA.

[0101] During the SU MIMO sounding process, when the beamformer is a non-AP STA for UL MIMO, the sounding should again include an NDP announcement (NDP-A), which contains information about the number of streams for which feedback is requested. NDPA and NDP should be received not only by STAs associated with AP1 and planning to participate in the sounding, but also by oSTAs and the corresponding oAP. Currently, non-AP STAs are not allowed to send trigger frames. Therefore, when the STA is a non-AP STA, SU MIMO sounding can be advanced by a trigger from the primary AP (AP1) that announces the start of SU-MIMO sounding with an SR opportunity. The rest of the process is in Figure 7 Depicted in Figure 7 A diagram illustrating SU MIMO uplink sounding using the spatial multiplexing phase for non-AP STAs is shown. (1) 、R1 (2) The trigger frame is sent after the NDP of the channel estimation sequence. The goal of this is to trigger potential oSTAs to signal their need to participate in subsequent uplink transmissions, as well as to allow the AP and corresponding oAPs to estimate the channel between these oSTAs and themselves, i.e., R2 in this example. (1) , R2 (2) .

[0102] The feedback contains updated uplink beamforming vector information, such as the one the STA should use when sending to the AP. In addition, as an addition to the feedback information to the STA, spatial multiplexing specific parameters may be sent to the oSTA along with information about the maximum allowed transmit power, allocation ID, and possible scheduling (if known), such as an acknowledgement to the oSTA that the oSTA may share the RU with the STA.

[0103] Based on the oSTA channel and traffic information, the AP can limit the number of UL flows of its associated STAs to ensure UL SR transmissions of the oSTAs under certain conditions, for example, if these have high priority traffic. Such modifications are then also notified in the feedback frame.

[0104] Similar to the previous case, if the oSTAs are known, they can be informed which channel estimation sequences to use, in which case channels from multiple oSTAs can be estimated simultaneously. If the oSTAs are not known, this can be applied in the case of BFRP triggering and NFRP triggering as well as in Figure 5 The feedback may be preceded by an information exchange between the APs involved and the oAP in order for the former to obtain SR feasibility and parameter updates from the latter, as discussed above for the case of DL probing using SR. If this is done in the same frequency band, the trigger and the trigger-based PPDU response precede the feedback transmission. However, this exchange may be performed on a different frequency band than the rest of the process, either via a wired backhaul or over the air, for which reason the feedback is not described in detail in the text of this document. Figure 7 Not shown.

[0105] Figure 8 A schematic diagram illustrating another embodiment of enhanced detection is shown. In this embodiment, it is assumed that oSTA information (AID and BSS identification, delayed service type requirements) has been collected in the stage before the detection phase. In this case, the AP starts the detection phase of its associated STAs. After obtaining the channel information from the requested STA, based on the requirements of the STA and oSTA, the AP decides which pairs of STA and oSTA should train together, that is, send data units with channel estimation sequences in the same frequency band and time interval. These STAs and oSTAs are triggered to send the described packets, and the oAP is triggered to estimate the channels of the corresponding pairs and calculate the SR criteria. The final feedback or multi-STA Ack contains information about SR parameters (i.e., transmit power and SR feasibility).

[0106] Fig. 9 A flow chart of a method used by a first access point is shown. The method may be performed by circuitry (e.g., a processor or a computer) of the first access point and includes the following steps:

[0107] - communicating with one or more first stations associated with the first access point (step S30);

[0108] - Sending a trigger, the trigger requesting the station to send a data unit containing a channel estimation sequence and / or channel feedback information enabling channel estimation (step S31);

[0109] - determining channel information based on channel estimation sequences and / or channel feedback information sent from one or more of said first stations and from one or more second stations associated with a second access point (step S32); and

[0110] -Determine spatial multiplexing parameters based on the determined channel information for the first access point to use for receiving data during the period when one or more of the second stations perform spatial multiplexing on resources allocated to one or more of the first stations, the first station is used to send data to the first access point, and the second station is used to send data to the second access point (step S33).

[0111] Fig.10 A flow chart of a method used by a second station is shown. The method may be performed by a circuit (e.g., a processor or a computer) of the second station and comprises the following steps:

[0112] - communicating with an associated second access point (step S40);

[0113] - receiving a trigger from a first access point associated with one or more first stations, the trigger requesting the station to send a data unit containing a channel estimation sequence and / or channel feedback information enabling channel estimation (step S41);

[0114] - Sending a channel estimation sequence and / or channel feedback information capable of implementing channel estimation to the first access point (step S42);

[0115] - receiving an individual transmit power level or an individual transmit power limit from the second access point or the first access point (step S43);

[0116] - receiving resource allocation information indicating resource units allocated to the second station for spatial multiplexing from the first access point (step S44); and

[0117] -During spatial multiplexing of resources allocated by the first access point to one or more first stations, data is transmitted using the allocated resource units and the received individual transmit power level or a transmit power level equal to or lower than the received individual transmit power limit, wherein the first stations are used to send data to the first access point (step S45).

[0118] Fig.11 A flow chart of a method used by a second access point is shown. The method may be performed by circuitry (e.g., a processor or a computer) of the second access point and includes the following steps:

[0119] - communicating with one or more second stations associated with the second access point (step S50);

[0120] - receiving a trigger from the first access point to start estimating a channel between the second access point and one or more first stations and / or one or more second stations associated with the first access point (step S51);

[0121] - determining channel information based on data units sent from one or more of the first stations and one or more of the second stations, the data units containing a channel estimation sequence and / or channel feedback information enabling channel estimation (step S52);

[0122] - identifying one or more second stations using resource units allocated by the first access point for spatial multiplexing and / or random access (step S53); and

[0123] - Sending identification information to the first access point, the identification information indicating whether spatial multiplexing is possible and / or considered for one or more second stations (step S54).

[0124] According to the present disclosure, a number of new elements are thus presented, as will be briefly summarized below.

[0125] The first access point (AP) may be specifically configured to perform one or more of the following functions:

[0126] - It can identify a group of STAs that can transmit on a specific resource unit to an AP different from itself.

[0127] - It can simultaneously trigger a STA to send data on a specific resource unit and one or more STAs to send data on the same resource unit but to one or more different APs.

[0128] - It can identify oSTAs (known and unknown, i.e., specifically addressed oSTAs or oSTAs from a set of specifically addressed STAs) that can share spatial multiplexing resource units with its own STAs based on criteria that depend on the receive beamforming capabilities at the AP and the QoS requirements of the STAs sending to the AP.

[0129] - It can specifically address one or more overlapping STAs, which can send to the oAP during SR.

[0130] - It can address a group of one or more overlapping STAs that can transmit during SR to allow one oSTA in the group to transmit. In addition, it can advertise the spatial multiplexing parameters that the oSTA should use in its transmission.

[0131] -It can send a beamforming trigger where some resources are allocated to its associated STA, allowing it to send BF feedback, and the remaining resources are either unallocated or allocated in broadcast mode to STAs in the overlapping BSSS. This allows STAs from overlapping BSSs to indicate that they need to be triggered, overlapping STAs to access random resources in a contention manner, and / or overlapping STAs to respond with a pilot pattern belonging to a set specific to the AID and BSS combination.

[0132] - It can simultaneously collect information about overlapping STAs that need to transmit and beamforming feedback of associated STAs.

[0133] - It can trigger oSTA to send NDP packets to AP and corresponding oAP to collect channel information.

[0134] - It can estimate the channels from a STA and an oSTA simultaneously on one resource unit.

[0135] - It can allocate RUs in NFRP triggers to different oBSSs, and overlapping STAs respond with pilot patterns belonging to a set specific to an AID and BSS combination. The mapping between pilot patterns and AIDs can be defined in the standard and known at the AP, or can be selected by the AP and announced to all APs and STAs participating in SR training.

[0136] - Based on the fixed uplink power level from the STA and the channel information from the STA and the oSTA, it can design the receive beamformer as a generalized eigenvector and determine the uplink power limit that can be used by the oSTA in the spatially multiplexed uplink timeslot.

[0137] - It can adjust the uplink transmit power of a STA to allow spatial multiplexing with a specific oSTA.

[0138] The second access point (oAP) may be specifically configured to perform one or more of the following functions:

[0139] - It can calculate the SR feasibility criteria based on the channel information, its own receive beamforming capability and the fixed uplink power from the STA.

[0140] - It may send a recommendation for a power update of the STA to allow SR for its associated oSA.

[0141] - It may send the AID set of the oSTAs associated with it to the AP, enabling the latter to identify the oSTAs.

[0142] - It can receive from STA and oSTA within IFS starting from the reception of the trigger frame.

[0143] In summary, a method is proposed by which an AP can identify and trigger stations with strict delay requirements or with periodic traffic to be transmitted to their corresponding AP simultaneously with uplink traffic from its own service set. The existing spatial multiplexing can be improved to take into account the receive beamforming capabilities at the AP. In addition, a method is proposed to collect channel information in an efficient manner and enhance the triggering process to allow stations from overlapping cells to access the channel during transmit opportunities or resource units allocated to other users.

[0144] Therefore, the present disclosure provides one or more of the following advantages: The chances of STAs within an overlapping BSS accessing a channel during an uplink resource unit allocated to a specific STA can be increased, spatial multiplexing can be allowed in the uplink even if there are not enough degrees of freedom available in the downlink, and the training overhead needs to be reduced due to the integration of overlapping STA identification in the detection phase of the BSS.

[0145] Therefore, the foregoing discussion only discloses and describes exemplary embodiments of the present disclosure. As will be appreciated by those skilled in the art, the present disclosure may be implemented in other specific forms without departing from the spirit or essential features of the present disclosure. Therefore, the disclosure of the present disclosure is intended to be illustrative, rather than limiting, the scope of the present disclosure and other claims. The present disclosure (including any easily discernible variants taught herein) partially defines the scope of the aforementioned claim terms so that no inventive subject matter is dedicated to the public.

[0146] In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single element or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0147] To the extent that embodiments of the present disclosure have been described as being implemented at least in part by a data processing device controlled by software, it should be understood that non-transitory machine-readable media (such as optical disks, magnetic disks, semiconductor memories, etc.) carrying such software are also considered to represent embodiments of the present disclosure. In addition, such software may also be distributed in other forms (such as via the Internet or other wired or wireless telecommunication systems).

[0148] Elements of the disclosed apparatus, devices, and systems may be implemented by corresponding hardware and / or software elements (e.g., dedicated circuits such as application specific circuits). A circuit is a structural combination of electronic components including conventional circuit elements, integrated circuits including application specific integrated circuits, standard integrated circuits, application specific standard products, and field programmable gate arrays. In addition, a circuit includes a central processing unit, a graphics processing unit, and a microprocessor, which are programmed or configured according to software code. A circuit does not include pure software, although the circuit includes the above-mentioned hardware executing software.

[0149] The following is a list of further embodiments of the disclosed subject matter:

[0150] 1. A first access point, comprising a circuit configured to:

[0151] - communicating with one or more first stations associated with the first access point;

[0152] - sending a trigger requesting the station to send a data unit containing a channel estimation sequence and / or channel feedback information enabling channel estimation;

[0153] - determining channel information based on channel estimation sequences and / or channel feedback information sent from one or more of said first stations and from one or more of said second stations associated with a second access point; and

[0154] -Determine spatial multiplexing parameters based on the determined channel information for the first access point to use for receiving data during the period in which one or more of the second stations spatially multiplex resources allocated to one or more of the first stations, the first station being used to send data to the first access point, and the second station being used to send data to the second access point.

[0155] 2. According to the first access point defined in embodiment 1,

[0156] The circuit is configured to determine spatial multiplexing parameters to ensure that a signal-to-interference ratio or a signal-to-interference-plus-noise ratio at the first access point is above a threshold, or that a signal-to-interference condition or a signal-to-interference-plus-noise condition is met during spatial multiplexing.

[0157] 3. A first access point as defined in any preceding embodiment,

[0158] The circuit is configured to determine a beamforming vector as a spatial multiplexing parameter, the beamforming vector defining a beamforming configuration used by the first access point to receive data sent by one or more of the first stations during spatial multiplexing.

[0159] 4. According to the first access point defined in embodiment 3,

[0160] Wherein the circuit is configured to determine the beamforming vector by solving a generalized eigenvector or singular vector problem.

[0161] 5. A first access point according to any of the preceding embodiments,

[0162] The circuit is configured to determine resource allocation information and / or spatial multiplexing feasibility information as spatial multiplexing parameters, the resource allocation information indicating the time and frequency of allocating resources to one or more of the second stations for sending data to the second access point, and the spatial multiplexing feasibility information indicating the feasibility of spatial multiplexing.

[0163] 6. A first access point as defined in any preceding embodiment,

[0164] Therein, the circuit is configured to determine, as a spatial multiplexing parameter, a separate transmit power level and / or a transmit power limit for transmitting data by one or more first stations and one or more second stations during spatial multiplexing.

[0165] 7. A first access point as defined in any preceding embodiment,

[0166] The circuit is configured to adjust one or more of the determined individual transmit power levels by using feedback from the second access point, the feedback indicating whether the second access point can receive data transmitted from one or more second stations with a desired quality, or making a suggestion for spatial multiplexing parameters to be used in order to ensure that data transmitted from the one or more second stations is received with a desired quality.

[0167] 8. A first access point as defined in any preceding embodiment,

[0168] Wherein the circuit is configured to notify the first station and the second station of one or more of the following:

[0169] - a separate transmit power level for use by one or more of said second stations in transmitting data to a second access point;

[0170] - an identifier of a second station, which allows to reuse resources allocated to one or more first stations;

[0171] - Time and frequency information of the resource unit, which can be used by the respective first station and / or second station.

[0172] 9. A first access point as defined in any preceding embodiment,

[0173] The circuit is configured to identify whether there is a second station and / or which second station expects to utilize spatial multiplexing by receiving a channel estimation sequence and identification information in a resource unit allocated to random access or spatial multiplexing from the second station, or by receiving a channel estimation sequence sent together with a pilot pattern corresponding to an identifier of the second station.

[0174] 10. A first access point as defined in any preceding embodiment,

[0175] The circuit is configured to: send an announcement to notify the first station, the second station and the second access point of the start of a channel sounding interval including a spatial multiplexing phase; and / or send a channel estimation sequence that allows the first station and the second station to estimate channel information and receive channel feedback information from the first station and / or the second station.

[0176] 11. The first access point defined in embodiment 10,

[0177] Therein, the circuit is configured to perform a triggered transmission in the spatial multiplexing stage, the triggered transmission having at least one allocated resource so that a known or unknown second station can transmit and the access point can estimate a channel from the second station.

[0178] 12. A first access point as defined in any preceding embodiment,

[0179] The circuit is configured to: send information included in a trigger, the information indicating which channel estimation sequences in a set of orthogonal channel estimation sequences should be used for transmission by the first station and the second station; and receive a data unit having a first channel estimation sequence orthogonal to the channel estimation sequence received from the second station from the first station.

[0180] 13. A first access point as defined in any preceding embodiment,

[0181] Wherein the circuit is configured to send allocation information indicating one or more of the following:

[0182] - a first resource unit allocated to one or more first stations to send channel information or a channel estimation sequence;

[0183] - a second resource unit allocated to one or more second stations to send an indication that they should perform spatial multiplexing or that they should send a channel estimation sequence;

[0184] - A third resource unit, which is allocated to a specific addressed set of one or more second stations, from which only second stations that need access to the channel and possibly a spatial multiplexing pattern can respond in a given time interval.

[0185] 14. A first access point as defined in any preceding embodiment,

[0186] The circuit is configured to send one or more of the following to the second access point:

[0187] - a request to estimate a channel between the second access point and the first station and the second; and

[0188] - If one or more second stations require spatial multiplexing, send information and send a request for identification information of the one or more second stations that require spatial multiplexing.

[0189] 15. A first access point as defined in any preceding embodiment,

[0190] Therein, the circuitry is configured to determine whether spatial multiplexing is possible for one or more stations, and with which parameters spatial multiplexing is possible.

[0191] 16. A second station comprising a circuit configured to:

[0192] - communicating with an associated second access point;

[0193] - receiving a trigger from a first access point associated with one or more first stations, the trigger requesting the station to send a data unit containing a channel estimation sequence and / or channel feedback information enabling channel estimation;

[0194] -sending a channel estimation sequence and / or channel feedback information enabling channel estimation to the first access point;

[0195] - receiving an individual transmit power level or an individual transmit power limit from the second access point or the first access point;

[0196] - receiving from the first access point resource allocation information indicating resource units allocated to the second station for spatial multiplexing; and

[0197] - during spatial multiplexing of resources allocated by the first access point to one or more of the first stations, transmitting data using the allocated resource units and a received individual transmit power level or a transmit power level equal to or lower than a received individual transmit power limit, the first stations being used to transmit data to the first access point.

[0198] 17. The second station as defined in embodiment 16,

[0199] The circuit is configured to simultaneously send the channel information and identification information for identifying the second station, or to send it using a pilot pattern corresponding to the identification information.

[0200] 18. The second station as defined in embodiment 16 or 17,

[0201] The circuit is configured to: receive an announcement from the first access point, which notifies the second station of the start of a channel sounding interval allowing spatial multiplexing; and / or receive a channel estimation sequence from the first access point, which allows the second station to estimate channel information so as to subsequently send the estimated channel information to the first access point in response to a trigger.

[0202] 19. A second station as defined in any one of embodiments 16 to 18,

[0203] Wherein the circuit is configured to send to the first access point a first channel estimation sequence that is orthogonal to a channel estimation sequence sent by any other station.

[0204] 20. The second station defined in embodiment 19,

[0205] Therein, the circuit is configured to derive, from the trigger, information indicating which orthogonal channel estimation sequence to send.

[0206] 21. A second station as defined in any one of embodiments 16 to 20,

[0207] The circuit is configured to receive allocation information indicating one or more first resource units allocated to one or more first stations and indicating one or more second resource units allocated to a second station or unallocated.

[0208] 22. A second access point comprising circuitry configured to:

[0209] - communicating with one or more second stations associated with the second access point;

[0210] - receiving a trigger from the first access point to start estimating a channel between the second access point and one or more first stations and / or one or more second stations associated with the first access point;

[0211] - determining channel information based on data units sent from one or more of said first stations and one or more of said second stations, said data units comprising a channel estimation sequence and / or channel feedback information enabling channel estimation;

[0212] - identifying one or more second stations using resource units allocated by said first access point for spatial multiplexing and / or random access; and

[0213] - sending identification information to the first access point, said identification information whether spatial multiplexing is possible and / or considered for one or more second stations.

[0214] 23. The second access point defined in embodiment 22,

[0215] Wherein the circuitry is configured to send, to the first access point, a transmit power recommendation indicating a transmit power recommended for use by one or more second stations for which spatial multiplexing is possible.

[0216] 24. The second access point defined in embodiment 22 or 23,

[0217] The circuit is configured to notify one or more second stations that they can participate in the spatial multiplexing detection phase and / or can use spatial multiplexing and / or which pilot patterns should be used, and for which one or more second stations, spatial multiplexing is considered; and / or send a set of identifiers to the second stations to let the second stations know which pilot patterns to use.

[0218] 25. A method for use by a first access point, comprising:

[0219] - communicating with one or more first stations associated with the first access point;

[0220] - sending a trigger requesting the station to send a data unit containing a channel estimation sequence and / or channel feedback information enabling channel estimation;

[0221] - determining channel information based on channel estimation sequences and / or said channel feedback information transmitted from one or more of said first stations and from one or more second stations associated with a second access point, and

[0222] -Determine spatial multiplexing parameters based on the determined channel information for the first access point to use for receiving data during the period in which one or more of the second stations spatially multiplex resources allocated to one or more of the first stations, the first station being used to send data to the first access point, and the second station being used to send data to the second access point.

[0223] 26. A method for use by a second station, comprising:

[0224] - communicating with an associated second access point;

[0225] - receiving a trigger from a first access point associated with one or more first stations, the trigger requesting the station to send a data unit containing a channel estimation sequence and / or channel feedback information enabling channel estimation;

[0226] -sending a channel estimation sequence and / or channel feedback information enabling channel estimation to the first access point;

[0227] - receiving an individual transmit power level or an individual transmit power limit from the second access point or the first access point;

[0228] - receiving resource allocation information from the first access point indicating resource units allocated to the second station for spatial multiplexing; and

[0229] - during spatial multiplexing of resources allocated by the first access point to one or more of the first stations, transmitting data using the allocated resource units and a received individual transmit power level or a transmit power level equal to or lower than a received individual transmit power limit, the first stations being used to transmit data to the first access point.

[0230] 27. A method for use by a second access point, comprising:

[0231] - communicating with one or more second stations associated with the second access point;

[0232] - receiving a trigger from the first access point to start estimating a channel between the second access point and one or more first stations and / or one or more second stations associated with the first access point;

[0233] - determining channel information based on data units sent from one or more of said first stations and one or more of said second stations, said data units comprising a channel estimation sequence and / or channel feedback information enabling channel estimation;

[0234] - identifying one or more second stations using resource units allocated by said first access point for spatial multiplexing and / or random access; and

[0235] - sending identification information to the first access point, the identification information indicating whether spatial multiplexing is possible and / or considered for one or more second stations.

[0236] 28. A non-transitory computer-readable recording medium storing a computer program product, which, when executed by a processor, causes the method according to embodiment 26 or 27 to be performed.

[0237] 29. A computer program comprising program code means for causing a computer to perform the steps of the method according to embodiment 26 or 27 when said computer program is executed on the computer.

[0238] 30. A first access point comprising circuitry configured to:

[0239] - communicating with one or more first stations associated with the first access point; and

[0240] - notifying one or more second stations associated with the second access point that the one or more second stations are allowed to transmit data to the associated second access point during spatial multiplexing of resources allocated to the one or more first stations for transmitting data to the first access point.

[0241] 31. The first access point according to embodiment 30,

[0242] Therein, the circuitry is configured to notify one or more notified second stations of spatial multiplexing parameters that should be used to transmit data.

[0243] 32. The first access point according to embodiment 30 or 31,

[0244] Wherein, the circuit is further configured as defined in any one of Embodiments 1 to 15.

[0245] 33. A method for use by a first access point, comprising:

[0246] - communicating with one or more first stations associated with the first access point; and

[0247] - notifying one or more second stations associated with the second access point that the one or more second stations are allowed to transmit data to the associated second access point during spatial multiplexing of resources allocated to the one or more first stations for transmitting data to the first access point.

Claims

1. A first access point, comprising a circuit, wherein the first access point is configured to: - communicating with one or more first stations associated with the first access point; - sending a trigger, wherein the trigger requests the station to send a data unit containing channel feedback information and / or a channel estimation sequence enabling channel estimation; - determining channel information based on the channel estimation sequence and / or the channel feedback information sent from one or more of the first stations and from one or more second stations associated with a second access point; as well as -Determine a spatial multiplexing parameter based on the determined channel information for the first access point to use for receiving data during a period in which one or more of the second stations spatially multiplex resources allocated to one or more of the first stations, the first station being used to send data to the first access point, and the second station being used to send data to the second access point.

2. The first access point according to claim 1, in, The circuit is configured to determine the spatial multiplexing parameters to ensure that a signal-to-interference ratio or a signal-to-interference-plus-noise ratio at the first access point is above a threshold, or a signal-to-interference condition or a signal-to-interference-plus-noise condition is met during the spatial multiplexing.

3. The first access point according to claim 1, in, The circuit is configured to determine one or more of the following as spatial multiplexing parameters: - a beamforming vector defining a beamforming configuration used by said first access point for receiving data transmitted by one or more of said first stations during said spatial multiplexing; - resource allocation information indicating a time and frequency at which resources are allocated to one or more of the second stations for transmitting data to the second access point; -spatial multiplexing feasibility information, indicating the feasibility of spatial multiplexing; as well as - separate transmit power levels and / or transmit power limits for transmitting data by one or more of said first stations and one or more of said second stations during said spatial multiplexing.

4. The first access point according to claim 1, in, The circuit is configured to notify the first station and the second station of one or more of: - a separate transmit power level for use by one or more of said second stations in transmitting data to said second access point; - an identifier of said second station, allowing to reuse resources allocated to one or more of said first stations; - Time and frequency information of the resource unit, which can be used by the respective first station and / or second station.

5. The first access point according to claim 1, in, The circuit is configured to identify whether there is a second station and / or which second station desires to utilize spatial multiplexing by receiving a channel estimation sequence and identification information in a resource unit allocated to random access or spatial multiplexing from the second station, or by receiving a channel estimation sequence sent together with a pilot pattern corresponding to an identifier of the second station.

6. The first access point according to claim 1, in, The circuit is configured to: send an announcement to notify the first station and the second station and the second access point of the start of a channel sounding interval including a spatial multiplexing phase; and / or send a channel estimation sequence, which allows the first station and the second station to estimate the channel information and receive channel feedback information from the first station and / or the second station.

7. The first access point according to claim 6, in, The circuit is configured to perform a triggered transmission with at least one resource allocated in the spatial multiplexing stage so that a known or unknown second station can transmit and an access point can estimate a channel from the second station.

8. The first access point according to claim 1, in, The circuit is configured to: transmit information included in the trigger, the information indicating which channel estimation sequences in a set of orthogonal channel estimation sequences should be used for transmissions by the first station and the second station; and receiving, from the first station, a data unit having a first channel estimation sequence orthogonal to the channel estimation sequence received from the second station.

9. The first access point according to claim 1, in, The circuitry is configured to send allocation information indicating one or more of: - a first resource unit, allocated to one or more of the first stations to send channel information or a channel estimation sequence; - a second resource unit allocated to one or more of the second stations to send an indication that one or more of the second stations should perform spatial multiplexing or one or more of the second stations should send a channel estimation sequence; - A third resource unit, allocated to a specific addressed set of one or more of said second stations, to which only second stations requiring access to the channel and requiring a spatial multiplexing mode should respond in a given time interval.

10. The first access point according to claim 1, in, The circuitry is configured to send one or more of the following to the second access point: - a request to estimate a channel between the second access point and the first station and the second station; and - if one or more of the second stations require spatial multiplexing, sending information and sending a request for identification information of the one or more second stations that require spatial multiplexing; and / or Therein, the circuit is configured to determine whether spatial multiplexing is possible for one or more stations, and with which parameters spatial multiplexing is possible.

11. A second station, comprising a circuit, wherein the second station is configured to: - communicating with an associated second access point; - receiving a trigger from a first access point associated with one or more first stations, the trigger requesting the station to send a data unit containing channel feedback information and / or a channel estimation sequence enabling channel estimation; - sending the channel feedback information and / or the channel estimation sequence capable of implementing channel estimation to the first access point; - receiving an individual transmit power level or an individual transmit power limit from the second access point or the first access point; - receiving, from the first access point, resource allocation information indicating resource units allocated to the second station for spatial multiplexing; as well as - during spatial multiplexing of resources allocated by the first access point to one or more of the first stations, sending data using the allocated resource units and the received individual transmit power level or a transmit power level equal to or lower than the received individual transmit power limit, the first stations being used to send data to the first access point.

12. The second station according to claim 11, in, The circuit is configured to transmit the channel information and identification information identifying the second station simultaneously or with a pilot pattern corresponding to the identification information.

13. The second station according to claim 11, in, The circuit is configured to: receive an announcement from the first access point notifying the second station of a start of a channel sounding interval allowing spatial multiplexing; and / or receive a channel estimation sequence from the first access point allowing the second station to estimate channel information to subsequently send the estimated channel information to the first access point in response to a trigger; and / or receiving allocation information indicating one or more first resource units allocated to one or more of the first stations and indicating one or more second resource units allocated to the second stations or unallocated.

14. The second station according to claim 11, in, The circuitry is configured to send, to the first access point, a first channel estimation sequence that is orthogonal to a channel estimation sequence sent by any other station and / or derive, from the trigger, information indicating which orthogonal channel estimation sequence to send.

15. A second access point, comprising a circuit, wherein the second access point is configured to: - communicating with one or more second stations associated with the second access point; - receiving a trigger from a first access point to start estimating a channel between the second access point and one or more second stations and / or one or more first stations associated with the first access point; - determining channel information based on data units sent from one or more of said first stations and one or more of said second stations, said data units comprising channel feedback information and / or a channel estimation sequence enabling channel estimation; - identifying one or more of said second stations using resource units allocated by said first access point for spatial multiplexing or random access; as well as - sending identification information to said first access point, said identification information indicating whether spatial multiplexing is possible and / or considered for one or more of said second stations.

16. The second access point according to claim 15, in, The circuit is configured to: send a transmit power recommendation to the first access point indicating a transmit power recommended for use by one or more of the second stations, wherein spatial multiplexing is possible for one or more of the second stations; and / or notify one or more of the second stations that they can participate in a spatial multiplexing detection phase and / or can use spatial multiplexing and / or which pilot patterns should be used, wherein spatial multiplexing is considered for one or more of the second stations; and / or send a group identifier to the second stations to let the second stations know which pilot patterns to use.

17. A method for use by a first access point, comprising: - communicating with one or more first stations associated with the first access point; - sending a trigger, wherein the trigger requests the station to send a data unit containing channel feedback information and / or a channel estimation sequence enabling channel estimation; - determining channel information based on the channel estimation sequence and / or the channel feedback information sent from one or more of the first stations and from one or more second stations associated with a second access point; as well as -Determine a spatial multiplexing parameter based on the determined channel information for the first access point to use for receiving data during a period in which one or more of the second stations spatially multiplex resources allocated to one or more of the first stations, the first station being used to send data to the first access point, and the second station being used to send data to the second access point.

18. A method for use by a second station, comprising: - communicating with an associated second access point; - receiving a trigger from a first access point associated with one or more first stations, the trigger requesting the station to send a data unit containing channel feedback information and / or a channel estimation sequence enabling channel estimation; - sending the channel feedback information and / or the channel estimation sequence capable of implementing channel estimation to the first access point; - receiving an individual transmit power level or an individual transmit power limit from the second access point or the first access point; - receiving, from the first access point, resource allocation information indicating resource units allocated to the second station for spatial multiplexing; as well as - during spatial multiplexing of resources allocated by the first access point to one or more of the first stations, sending data using the allocated resource units and the received individual transmit power level or a transmit power level equal to or lower than the received individual transmit power limit, the first stations being used to send data to the first access point.

19. A method for use by a second access point, comprising: - communicating with one or more second stations associated with the second access point; - receiving a trigger from a first access point to start estimating a channel between the second access point and one or more second stations and / or one or more first stations associated with the first access point; - determining channel information based on data units sent from one or more of said first stations and one or more of said second stations, said data units comprising channel feedback information and / or a channel estimation sequence enabling channel estimation; - identifying one or more of said second stations using resource units allocated by said first access point for spatial multiplexing and / or random access; as well as - sending identification information to said first access point, said identification information indicating whether spatial multiplexing is possible and / or considered for one or more of said second stations.

20. A non-transitory computer-readable recording medium storing a computer program product, which, when executed by a processor, causes execution of the method according to any one of claims 17 to 19.

Images