Patent Description:
Beamforming is widely used in Wi-Fi communication systems as a technique to improve performance in MIMO scenarios, e.g. as shown in <FIG> where an access point <NUM> transmits in downlink direction to a plurality of client stations <NUM>, <NUM>, <NUM>, e.g. by using a wide beam <NUM>, and each client station <NUM>, <NUM>, <NUM> transmits in uplink direction towards the access point <NUM>, e.g. by using a narrow beam <NUM>, <NUM>, <NUM>. IEEE <NUM>. 11n/ac/ax support feedback of precoding matrices that can be used for beamforming. Many contributions and much research were carried out in order to examine the properties of beamforming and design efficient methods to support it. However, the procedures are optimized mostly for downlink transmission and may be (partially or non-efficiently) reused by the uplink. When applying the currently existing procedures of downlink beamforming to the uplink, various problems will arise as the uplink transmission is different from the downlink transmission.

DL beamforming is fully managed by the AP <NUM> while the precoder can be adjusted according to currently scheduled transmission. Different transmission schemes may require different precoders to achieve better performance - SU, MU, MU-MIMO. AP <NUM> collects the feedback information from different stations <NUM>, <NUM>, <NUM> and may compute the relevant precoder optimized for specific packet, e.g. as shown in <FIG> where after NDPA <NUM>, NDP <NUM>, trigger frame <NUM> and Multi User Feedback <NUM> transmission, different precoders may be required for STA1, <NUM> to achieve better performance: SU Data STA1, <NUM>, MU-MIMO STA1&<NUM>, <NUM>, and MU-MIMO STA1&<NUM>, <NUM>.

In UL the same procedure is applied while the STA acts as a beamformer and thus triggers the procedure and collects the precoder feedback from a beamformee (AP), see <FIG> where after NDPA <NUM>, NDP <NUM>, trigger frame <NUM> and Multi User Feedback <NUM> transmission, SU Data STA1 transmission <NUM> is performed. This means that STA holds the precoder information and decides when and which precoder to apply.

Similar to DL, different precoders may be required in UL for several reasons as for example: Nonorthogonal precoder - SVD based precoder may be not optimal if Nss > <NUM> (same STA may transmit with different Nss in MU and MU-MIMO); Decoder type relaxation - AP may adjust a precoder type for a detector that will be applied, for example to use MMSE instead of ML to detect MU-MIMO; Null Steering - advanced interference mitigation schemes may require different precoder adjusted to current interference spatial properties. However, currently access point (AP) cannot update and inform STAs regarding specific precoder that should be applied in the next UL frame.

A beamformee is a receiver that is capable of obtaining, calculating and returning (i.e. feeding back) beamforming data, e.g. in accordance with a protocol (e.g. a WiFi protocol) and is capable of participating in a sounding procedure. These capabilities are mandatory for WiFi receivers. Hence, any WiFi receiver can operate as a beamformee.

<CIT> discloses a kind of indicating means of resource allocation and relevant device.

<CIT> discloses communication networks and, more particularly, to sounding methods in wireless local area networks based on OFDMA and MU-MIMO. <CIT> discloses frame formats for orthogonal frequency division multiple access (OFDMA) and multi-user multiple-input multiple-output (MU-MIMO) uplink feedback transmissions in packet based wireless systems, for example IEEE <NUM>.

It is the object of the invention to provide an efficient technique for solving the above described problems when applying the currently existing procedures for UL beamforming.

This object is achieved by the features of the independent claims.

A main idea of the invention is to transmit, by a beamformee device, e.g. a WiFi access point, to one or more beamformer devices, e.g. WiFi client stations, an indication of a precoder for Uplink transmission per Uplink transmission. In this disclosure an adjustment of the precoder per UL frame is justified and a method that supports it is presented.

In orderto describe the invention in detail, the following terms, abbreviations and notations will be used:.

According to a first aspect, the invention relates to a method for managing beamformed uplink transmissions of one or more beamformer devices, e.g. WiFi client stations, wherein the method is initialized by a beamformee device, e.g. a WiFi access point, the method comprising: transmitting, by a beamformee device, e.g. a WiFi access point, to one or more beamformer devices, e.g. WiFi client stations, an indication of a precoder for Uplink transmission per Uplink transmission.

This provides the advantage that such a method optimizes beamformed transmission in the uplink direction, i.e. from a beamformer device, e.g. a WiFi client station, to the beamformee device, e.g. a WiFi access point. Better antenna gains can be achieved when this method is applied where a precoder for Uplink transmission per Uplink transmission is indicated.

The above described problems can be overcome, i.e., SVD based precoder can be optimally designed even if Nss > <NUM>; AP can adjust a precoder type for a detector that will be applied, advanced interference mitigation schemes can be applied which require different precoder adjusted to current interference spatial properties. AP can update and inform STAs regarding specific precoder that should be applied in the next UL frame.

The method comprises transmitting, by the beamformee device, a trigger frame to the one or more beamformer devices, wherein the trigger frame comprises the indication of the precoder.

This provides the advantage that in various technologies such as WiFi <NUM>. 11ax or <NUM>. 11be a trigger frame is already defined and existing that can be efficiently used to transport this additional information of precoder for Uplink transmission per Uplink transmission. Thus, a standard compatible solution can be provided.

In an exemplary implementation form of the method, the trigger frame comprises an indication of a specific precoder per uplink transmission that is based on previously collected channel state information, wherein the specific precoder is included within the trigger frame.

This provides the advantage that an optimal precoder can be used for UL transmission when a selection of the precoder is based on channel state information.

In an exemplary implementation form, the method comprises: selecting, by the beamformee device, a precoder per beamformer device from a set of precoders produced for different uplink transmissions; and indicating the selected precoder per beamformer device in the trigger frame.

This provides the advantage that no complex processing tasks for determining an optimal precoder is necessary, instead an easy selection from a given set of precoders, e.g. from a lookup table can be applied.

In an exemplary implementation form, the method comprises: selecting, by the beamformee device, a precoder per beamformer device for different types of uplink transmissions, wherein the different types of uplink transmissions are from the following: Single-User, SU, Multiple-User, MU, Multiple-User-MIMO, or from further types of uplink transmissions.

This provides the advantage that the indication of the precoder can be applied in multiple modes of beamformed communications such as SU, MU, MU-MIMO and others.

In an exemplary implementation form of the method, the trigger frame comprises a trigger frame indication field that includes the following information per beamformer device scheduled for the next uplink transmission: precoder type indication for indicating which type of precoder to use, and precoder data, e.g. wideband precoder data or codebook based precoder data with Precoding Matrix Indicator, PMI.

This provides the advantage that the trigger frame indication field can transport all relevant data required by the beamformer devices from the beamformee device to beamformer devices.

In an exemplary implementation form of the method, the precoder type indication indicates one of the following precoder types: first type: no precoder required, second type: last updated precoder to be used, third type: precoder indicated in trigger frame to be used, fourth type: precoder update will follow the trigger frame, by special precoder update frame, or further types of precoders.

This provides the advantage that the indication of precoder can be flexibly applied in different situations and environments, in particular for saving resources.

The method comprises: transmitting, by a beamformee device, a channel sounding announcement, e.g. a Null Data Packet Announcement, NDPA, for prompting the beamformer devices initiating a channel sounding procedure, and to receive a corresponding channel sounding frame, e.g. a Null Data Packet, NDP, from the beamformer devices responsive to the channel sounding announcement; transmitting, by the beamformee device, a feedback frame to a respective channel sounding frame, and transmitting, by the beamformee device, two or more different feedback update frames for updating a beamformer device with new precoding information to the same beamformer device based on the same channel sounding frame.

This provides the advantage that the novel mechanism of precoder indication can be easily and flexible adopted to the existing NDPA-NDP channel sounding procedure.

In an exemplary implementation form, the method comprises: transmitting, by the beamformee device, multiple feedback frames between two NDPA-NDP transmissions.

This provides an advantage of higher flexibility. Such feedback frames can provide information updates and channel state information. This allows the beamformee device, e.g. the AP, to collect CSI, and to decide later which precoder should be applied for a specific UL frame.

In an exemplary implementation form, the method comprises: computing, by the beamformee device, CSI information from the channel sounding procedure and; assigning a precoder to a respective beamformer device based on the computed CSI information.

This provides the advantage that based on the computed CSI information an optimal precoder can be determined.

In an exemplary implementation form of the method, the feedback update frame comprises one of the following: precoding matrices data based on previously performed channel sounding procedure, e.g. NDPA-NDP procedure, feedback type indication to allow further usage of the same precoder.

This provides the advantage that by using the same precoder, no complex processing tasks have to be performed by the beamformer device.

In an exemplary implementation form of the method, the trigger frame comprises common information and per user information, e.g. as defined by <NUM>. 11ax WiFi communications standard, wherein the per user information comprises trigger dependent user information which indicates a precoder for Uplink beamforming.

This provides the advantage that the precoder for Uplink beamforming can be easily added in the trigger frame format as defined by the WiFi standard, e.g. <NUM>. 11ax or <NUM>. 11be, thereby providing standard compliance of this new mechanism.

In an exemplary implementation form of the method, the trigger dependent user information indicates to use a last updated precoding matrix by not explicitly indicating a precoding matrix.

This provides the advantage that resources can be saved and complexity reduced when further using the last updated precoding matrix.

In an exemplary implementation form of the method, the trigger dependent user information comprises a precoding matrix to use.

This provides the advantage that precoding matrix can be easily transmitted to the beamformer device. The beamformer device can apply this precoding matrix to improve its beamformed transmission.

In an exemplary implementation form of the method, the trigger dependent user information comprises a Precoding Matrix Index, PMI, to indicate a precoding matrix from a predefined codebook.

This provides the advantage that by using a PMI, there is no need for transmitting the whole precoder from beamformee device to the beamformer devices which saves radio and processing resources.

According to a second aspect, the invention relates to a beamformee device, e.g. a WiFi access point, for initiating beamformed uplink transmissions of one or more beamformer devices, e.g. WiFi client stations, wherein the beamformee device is configured to: transmit to one or more beamformer devices, e.g. WiFi client stations, an indication of a precoder for Uplink transmission per Uplink transmission, transmit a trigger frame to the one or more beamformer devices, wherein the trigger frame comprises the indication of the precoder; transmit a channel sounding announcement, for prompting the multiple beamformer devices initiating a channel sounding procedure, and to receive a corresponding channel sounding frame from the beamformer devices responsive to the channel sounding announcement; transmit a feedback frame to a respective channel sounding frame; transmit two or more different feedback update frames for updating a beamformer device with new precoding information to the same beamformer device based on the same channel sounding frame.

This provides the advantage that such a beamformee device optimizes beamformed transmission in Uplink direction, i.e. from the beamformer devices, e.g. WiFi client stations to the beamformee device, e.g. a WiFi access point. Better antenna gains can be achieved by using this beamformee device which indicates a precoder for Uplink transmission per Uplink transmission.

In an example, there is provided a radio device, e.g. an access point, for managing beamformed uplink transmissions of multiple client stations, wherein the radio device is configured to: transmit an indication of a precoder for beamformed Uplink transmission per Uplink transmission to the multiple client stations.

By using such a radio device and the following implementations thereof, the same advantages as described above with respect to the method according to the first aspect can be realized.

In an exemplary implementation form of the radio device, the radio device is configured to transmit a trigger frame to the multiple client stations, wherein the trigger frame comprises the indication of the precoder.

In an exemplary implementation form of the radio device, the trigger frame comprises an indication of a specific precoder per uplink transmission that is based on previously collected channel state information, wherein the specific precoder is included within the trigger frame.

In an exemplary implementation form of the radio device, the radio device is configured to select a precoder per client station from a set of precoders produced for different uplink transmissions and indicate the selected precoder per client station in the trigger frame.

In an exemplary implementation form of the radio device, the radio device is configured to select a precoder per client station for different types of uplink transmissions, wherein the different types of uplink transmissions are from the following: Single-User, SU, Multiple-User, MU, Multiple-User-MIMO, or from further types of uplink transmissions.

In an exemplary implementation form of the radio device, the trigger frame comprises a trigger frame indication field that includes the following information per client station scheduled for the next uplink transmission: precoder type indication for indicating which type of precoder to use, and precoder data for indicating precoding data, e.g. wideband precoder or codebook based precoder with Precoding Matrix Indicator, PMI.

In an exemplary implementation form of the radio device, the precoder type indication indicates one of the following precoder types: first type: no precoder required, second type: last updated precoder to be used, third type: precoder indicated in trigger frame to be used, fourth type: precoder update will follow the trigger frame, by special precoder update frame, or further types of precoders.

In an exemplary implementation form of the radio device, the radio device is configured to transmit a channel sounding announcement, e.g. a Null Data Packet Announcement, NDPA, for prompting the multiple client stations initiating a channel sounding procedure, and to receive a corresponding channel sounding frame, e.g. a Null Data Packet, NDP, from the multiple client stations responsive to the channel sounding announcement, wherein the radio device is configured to transmit a feedback frame to a respective channel sounding frame, and wherein the radio device is configured to transmit two or more different feedback update frames for updating a client station with new precoding information to the same client station based on the same channel sounding frame.

In an exemplary implementation form of the radio device, the radio device is configured to transmit multiple feedback frames between two NDPA-NDP transmissions.

In an exemplary implementation form of the radio device, the radio device is configured to compute CSI information from the channel sounding procedure and to assign a precoder to a respective client station based on the computed CSI information.

In an exemplary implementation form of the radio device, the feedback update frame comprises one of the following: precoding matrices data based on previously performed channel sounding procedure, e.g. NDPA-NDP procedure, feedback type indication to allow further usage of the same precoder.

In an exemplary implementation form of the radio device, the trigger frame comprises common information and per user information, e.g. as defined by <NUM>. 11ax WiFi communications standard, wherein the per user information comprises trigger dependent user information which indicates a precoder for Uplink beamforming.

In an exemplary implementation form of the radio device, the trigger dependent user information indicates to use a last updated precoding matrix by not explicitly indicating a precoding matrix.

In an exemplary implementation form of the radio device, the trigger dependent user information comprises a precoding matrix to use.

In an exemplary implementation form of the radio device, the trigger dependent user information comprises a Precoding Matrix Index, PMI, to indicate a precoding matrix from a predefined codebook.

According to an example there is provided a method for managing beamformed uplink transmissions of multiple client stations, wherein the method comprises: transmitting, by a radio device, e.g. an access point, an indication of a precoder for beamformed Uplink transmission per Uplink transmission to the multiple client stations.

Both the beamformee device and the beamformer devices can be implemented according to the WiFi communication standard such as <NUM>. 11ax and/or <NUM>.

Further embodiments of the invention will be described with respect to the following figures, in which:.

In the following detailed description, reference is made to the accompanying drawings, which form a part thereof, and in which is shown by way of illustration specific aspects in which the disclosure may be practiced. It is understood that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure.

It is understood that comments made in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa.

The described devices may include integrated circuits and/or passives and may be manufactured according to various technologies. For example, the circuits may be designed as logic integrated circuits, analog integrated circuits, mixed signal integrated circuits, optical circuits, memory circuits and/or integrated passives.

The methods and devices described herein may be implemented in wireless communication networks, e.g. communication networks based on WiFi communication standards according to IEEE <NUM>, e.g. IEEE <NUM>. The methods and devices described herein may also be implemented in wireless communication networks based on mobile communication standards such as LTE, e.g. <NUM>, <NUM> and beyond. The described devices may include integrated circuits and/or passives and may be manufactured according to various technologies. For example, the circuits may be designed as logic integrated circuits, analog integrated circuits, mixed signal integrated circuits, optical circuits, memory circuits and/or integrated passives.

The devices, methods and systems described herein may be configured to transmit and/or receive radio signals. Radio signals may be or may include radio frequency signals radiated by a radio transmitting device (or radio transmitter or sender) with a radio frequency lying in a range of about <NUM> to <NUM>. The frequency range may correspond to frequencies of alternating current electrical signals used to produce and detect radio waves.

The devices, methods and systems described herein may include processors. In the following description, the term "processor" describes any device that can be utilized for processing specific tasks (or blocks or steps). A processor can be a single processor or a multi-core processor or can include a set of processors or can include means for processing. A processor can process software or firmware or applications etc..

The devices, methods and systems described herein may process OFDM symbols with or without guard intervals. OFDM is a frequency-division multiplexing scheme used as a digital multi-carrier modulation method. A large number of closely spaced orthogonal sub-carrier signals are used to carry data on several parallel data streams or channels. Channel equalization is simplified because OFDM may be viewed as using many slowly modulated narrowband signals rather than one rapidly modulated wideband signal. The low symbol rate makes the use of a guard interval between symbols affordable, making it possible to eliminate intersymbol interference (ISI) and utilize echoes and time-spreading to achieve a diversity gain, i.e. a signal-to-noise ratio improvement. In OFDM, the beginning of each symbol is preceded by a guard interval. As long as the echoes fall within this interval, they will not affect the receiver's ability to safely decode the actual data, as data is only interpreted outside the guard interval.

The devices, methods and systems described herein may process radio signals including cyclic prefix. The term cyclic prefix refers to the prefixing of a symbol with a repetition of the end. Although the receiver is typically configured to discard the cyclic prefix samples, the cyclic prefix serves two purposes: As a guard interval, it eliminates the intersymbol interference from the previous symbol. As a repetition of the end of the symbol, it allows the linear convolution of a frequency-selective multipath channel to be modelled as circular convolution, which in turn may be transformed to the frequency domain using a discrete Fourier transform (DFT) or a Fast Fourier transform (FFT). This approach allows for simple frequency-domain processing, such as channel estimation and equalization.

The devices, methods and systems described herein may be configured to manage beamformed transmission. In the beamforming procedure, the beamformer initiates a channel sounding procedure with a Null Data Packet. The beamformee measures the channel and responds with a beamforming feedback frame, containing a compressed feedback matrix. The beamformer uses this information to compute the channel matrix. The beamformer can then use this channel matrix to focus the RF energy toward each user.

The methods and devices described herein may be implemented based on WiFi communication standards according to IEEE <NUM>, e.g. IEEE <NUM>. 11ax standard has two modes of operation: <NUM>) Single User: IN this sequential mode the wireless STAs send an receive data one at a time once they secure access to the medium; <NUM>) Multi-User: This mode allows for simultaneous operation of multiple non-AP STAs. The standard divides this mode further into Downlink and Uplink Multi-User. Under the Multi-User mode of operation, the standard also specifies two different ways of multiplexing more users within a certain area: Multi-User MIMO and Orthogonal Frequency Division Multiple Access (OFDMA). For both of these methods, the AP acts as the central controller of all aspects of multi-user operation. 11ax AP can also combine MU-MIMO with OFDMA operation.

Under the MU-MIMO method, <NUM>. 11ax devices will use beamforming techniques to direct packets simultaneously to spatially diverse users. That is, the AP will calculate a channel matrix for each user and steer simultaneous beams to different users, each beam containing specific packets for its target user. 11ax supports sending up to eight multi-user MIMO transmissions at a time, up from four for <NUM>. Also, each MU-MIMO transmission may have its own Modulation and Coding Set (MCS) and a different number of spatial streams. In the MU-MIMO Uplink direction, the AP can initiate a simultaneous uplink transmission from each of the STAs by means of a trigger frame. When the multiple users respond in unison with their own packets, the AP applies the channel matrix to the received beams and separates the information that each uplink beam contains. The AP may also initiate Uplink multi-user transmissions to receive beamforming feedback information from all participating STAs.

The Wi-Fi community is currently specifying IEEE <NUM>. 11be also referred to as EHT (Extremely High Throughput) WiFi that is targeted at: A) enabling new MAC and PHY modes of operation capable of supporting a maximum throughput of at least <NUM> Gbps, measured at the MAC data service access point (AP), i.e. about <NUM> times higher than IEEE <NUM>. 11ax using carrier frequencies between <NUM> and <NUM>, while B) ensuring backward compatibility and coexistence with legacy IEEE <NUM> devices in the <NUM>, <NUM> and <NUM>
unlicensed bands. The devices, methods and systems described in this disclosure may be implemented to be compliant with this new EHT WiFi standard.

The devices and systems described herein may include processors or processing devices or processing circuitries, memories and transceivers, i.e. transmitters and/or receivers for computing the beamformed transmissions. The term "processor" or "processing device" describes any device that can be utilized for processing specific tasks (or blocks or steps). A processor or processing device can be a single processor or a multi-core processor or can include a set of processors or can include means for processing. A processor or processing device can process software or firmware or applications etc..

<FIG> shows a schematic diagram of beamforming communication system <NUM> with an access point <NUM> and a plurality of client stations <NUM>, <NUM>, <NUM>.

In the beamforming communication system <NUM> an access point <NUM> transmits in downlink direction to a plurality of client stations <NUM>, <NUM>, <NUM>, e.g. by using a wide beam <NUM>, and each client station <NUM>, <NUM>, <NUM> transmits in uplink direction towards the access point <NUM>, e.g. by using a narrow beam <NUM>, <NUM>, <NUM>. The access point <NUM> may be designed to initiate the client stations <NUM>, <NUM>, <NUM> to perform a beamforming procedure as described in this disclosure.

<FIG> shows a schematic diagram illustrating an exemplary beamforming procedure application <NUM> in Downlink.

DL beamforming is fully managed by the AP <NUM>, e.g. AP <NUM> as shown in <FIG> while the precoder can be adjusted according to currently scheduled transmission. Different transmission schemes may require different precoders to achieve better performance - SU, MU, MU-MIMO. AP <NUM> collects the feedback information from different stations <NUM>, e.g. stations <NUM>, <NUM>, <NUM> as shown in <FIG>, and may compute the relevant precoder optimized for specific packet. For example, after NDPA <NUM>, NDP <NUM>, trigger frame <NUM> and Multi User Feedback <NUM> transmission, different precoders may be required for STA1, <NUM> to achieve better performance: SU Data STA1, <NUM>, MU-MIMO STA1&<NUM>, <NUM>, and MU-MIMO STA1&<NUM>, <NUM>.

<FIG> shows a schematic diagram illustrating an exemplary beamforming procedure application <NUM> in Uplink.

In UL the same procedure is applied as described above with respect to <FIG> while the STA <NUM> acts as a beamformer and thus triggers the procedure and collects the precoder feedback from beamformee (AP) <NUM>. After NDPA <NUM>, NDP <NUM>, trigger frame <NUM> and Multi User Feedback <NUM> transmission, SU Data STA1 transmission <NUM> can be performed. This means that STA <NUM> holds the precoder information and decides when and which precoder to apply.

<FIG> shows a schematic diagram illustrating an exemplary Trigger-based Uplink transmission <NUM>. The trigger-based Uplink transmission <NUM> includes a trigger frame <NUM> and MU Data <NUM>.

The trigger-based Uplink transmission <NUM> may be applied in the WiFi standard <NUM>. 11ax as a trigger based procedure for UL multiuser transmissions, including MU-MIMO.

This method can be used to allow the AP <NUM> to manage BF procedure and indicate the precoder to be applied. The method includes the following functionality: Trigger frame <NUM> may include an indication data to inform STA <NUM> regarding BF application per UL transmission. AP <NUM> can indicate a specific precoder per UL transmission (based on previously collected CSI data and STAs allocated within packet). AP <NUM> can produce a multiple precoders optimized for different transmissions and choose the relevant precoder per UL transmission
<FIG> shows a schematic diagram illustrating an exemplary transmission <NUM> including a trigger frame with precoder indication <NUM>. The whole transmission <NUM> includes an NDPA (Null Data Packet Announcement) frame <NUM>, an MU/SU NDP frame <NUM> following the NDPA <NUM> after a short interframe space (SIFS) <NUM>, a feedback frame <NUM>, after some time the trigger frame with precoder indication <NUM> and after a further SIFS <NUM> the Uplink data <NUM>.

The transmission <NUM> illustrates the concept of Precoder Update Per UL Frame. The main idea is to allow AP <NUM> to indicate to STAs <NUM> which precoder should be applied. The concept is to add to TF <NUM> relevant information that can both trigger a beamformed transmission and indicate which precoder should be applied.

<FIG> shows a schematic diagram illustrating an exemplary transmission <NUM> including a Precoding Indication Field Format <NUM>, <NUM>. The transmission <NUM> corresponds to the transmission <NUM> described above with respect to <FIG> with the difference that the trigger frame with precoder indication <NUM> comprises a plurality of data <NUM>, <NUM> providing user information for the respective clients or stations <NUM>.

The transmission <NUM> illustrates the concept of TF Precoder Indication Field. The TF indication field includes the following information per user <NUM>, <NUM> scheduled for the next UL transmission: <NUM>) Precoder type indication that indicates which type of precoder should be applied (including precoder update indication, see <FIG>); and <FIG>) Precoder data; in some cases the AP may use a trigger frame to carry the precoding data (for example, wideband precoder or codebook based precoder with PMI).

<FIG> shows a schematic diagram illustrating an exemplary transmission <NUM> including a Precoder Update Frame <NUM>. The transmission <NUM> includes the trigger frame with precoder indication <NUM> as described above with respect to <FIG> and <FIG>, the Precoder Update Frame <NUM> and UL data <NUM> that may be separated by SIFS <NUM>.

The concept of Precoder Type Indication is to indicate the Precoder type in the trigger frame <NUM>. Precoder type may imply usage of one of the precoders that was sent previously to STA <NUM> or may indicate that precoder update is transmitted or that precoder update will follow the TF <NUM>, by Precoder Update Frame <NUM>. The following indication is just for example, i.e. any other bit configuration may be used.

<FIG> shows a schematic diagram illustrating an exemplary transmission <NUM> including multiple feedback transmission <NUM> between an NDPA-NDP message <NUM>, <NUM>. The whole transmission <NUM> includes an NDPA (Null Data Packet Announcement) frame <NUM>, an MU/SU NDP frame <NUM> following the NDPA <NUM> after a SIFS <NUM>, a feedback frame <NUM>, after any time period <NUM> further feedback frame <NUM> and after any further time period <NUM> further NDPA <NUM> and further MU/SU NDP <NUM>.

NDPA-NDP procedure implicitly assumes immediate single feedback transmission and applying a precoder in the next frame. In this disclosure, a new method is introduced, where feedback transmission <NUM> can be done any time <NUM> after NDPA-NDP <NUM>, <NUM> is performed and multiple feedback transmission <NUM> may be done between two NDPA-NDP transmissions <NUM>, <NUM>. This allows the AP <NUM> to collect CSI information, and to decide later which precoder should be applied for a specific UL frame.

<FIG> shows a schematic diagram illustrating an exemplary transmission <NUM> including a Feedback Update Frame <NUM>. The whole transmission <NUM> includes an NDPA frame <NUM>, a MU/SU NDP frame <NUM> as described above with respect to <FIG> and after a time period <NUM> a feedback update frame <NUM>.

Precoder Update Frame Format is described in the following: AP <NUM> may calculate different precoders to apply for different types of UL transmissions (e.g. SU, MU, MU-MIMO with different groups). In order to update STAs <NUM> with new and relevant precoding matrices, the AP <NUM> may transmit a feedback update frame <NUM>. Feedback update frame <NUM> may be transmitted in SU or MU format. The feedback update frame <NUM> can include the following: Precoding matrices data based on previously performed NDPA-NDP procedure; and Feedback type indication - to allow further usage of the same precoder. Optionally, the feedback update frame <NUM> can include further information.

<FIG> shows a schematic diagram illustrating an exemplary implementation of a Trigger Frame Format <NUM> according to a first option.

In the first option, a new trigger type is used for EHT trigger frame or for a basic trigger type, a reserved bit is used to differentiate HE/EHT basic trigger frame. Precoding matrix is not indicated in the trigger frame but depends on the previous memorized feedback (one or multiple fields can exist). The Trigger Frame Format <NUM> includes common information <NUM> and per user information <NUM>, e.g. for users <NUM> to M. Each user-specific information <NUM> includes trigger-dependent user information <NUM> which includes, beside identifications Nc and Nr, codebook information <NUM> and feedback type <NUM>.

In trigger-based transmissions in extremely-high throughput (EHT) Wi-Fi systems, an access point <NUM> may generate a trigger frame compatible with two types of stations <NUM>, such as EHT STAs and legacy (or high efficiency (HE)) STAs. The AP may transmit the trigger frame to a group of STAs, where legacy STAs may process the trigger frame as a legacy trigger frame. EHT STAs may process the trigger frame to determine resource unit (RU) allocations for uplink transmissions in a bandwidth greater than a legacy bandwidth. An EHT STA may determine the resources in the larger bandwidth based on an EHT RU allocation table, a legacy RU allocation table and an additional bit in the trigger frame, or an ordering of RU allocations in the trigger frame.

<FIG> shows a schematic diagram illustrating an exemplary implementation of a Trigger Frame Format <NUM> according to a second option.

In the second option, a new trigger type is used for EHT trigger frame or for a basic trigger type, a reserved bit is used to differentiate HE/EHT basic trigger frame. Precoding matrix <NUM> is explicitly indicated in the trigger dependent user information <NUM> of the EHT trigger frame. One or multiple fields can exist.

The Trigger Frame Format <NUM> includes common information <NUM> and per user information <NUM>, e.g. for users <NUM> to M. Each user-specific information <NUM> includes trigger-dependent user information <NUM> which includes, beside identifications Nc and Nr, codebook information <NUM>, feedback type <NUM>, SNR <NUM> and Precoding matrix <NUM>.

<FIG> shows a schematic diagram illustrating an exemplary implementation of a Trigger Frame Format <NUM> according to a third option.

In the third option, a new trigger type is used for EHT trigger frame or for a basic trigger type, a reserved bit is used to differentiate HE/EHT basic trigger frame. A codebook is predefined. One or multiple fields can exist.

The Trigger Frame Format <NUM> includes common information <NUM> and per user information <NUM>, e.g. for users <NUM> to M. Each user-specific information <NUM> includes trigger-dependent user information <NUM> which includes, beside identifications Nc and Nr, codebook information <NUM>, feedback type <NUM>, and Precoding Matrix Index (PMI) <NUM>.

<FIG> shows a performance diagram <NUM> illustrating an exemplary single user (SU) performance when beamforming is applied in the Uplink while <FIG> shows a performance diagram <NUM> illustrating an exemplary multi user MIMO (MU-MIMO) performance when beamforming is applied in the Uplink.

Several simulations were performed to examine the gain that can be achieved if beamforming is applied in the UL. SU and MU-MIMO were simulated with the following parameters:.

It can be seen from <FIG> and <FIG> that beamforming outperforms non-pre-coded transmission by ~3dB; wideband beamforming provides a negligible degradation (~<NUM>.

In <FIG>, graph <NUM> shows narrowband beamforming, graph <NUM> shows wideband beamforming while graph <NUM> shows result without beamforming. In <FIG>, graph <NUM> shows narrowband beamforming, graph <NUM> shows wideband beamforming while graph <NUM> shows result without beamforming.

<FIG> shows a schematic diagram of a method <NUM> for managing beamformed uplink transmissions.

The method <NUM> is used for managing beamformed uplink transmissions of one or more beamformer devices <NUM>, e.g. as described above with respect to <FIG>, e.g. WiFi client stations <NUM>, <NUM>, <NUM>, e.g. as shown in <FIG>. The method <NUM> is initialized by a beamformee device <NUM>, e.g. a WiFi access point <NUM>. The method <NUM> comprises: transmitting <NUM>, by a beamformee device <NUM>, e.g. a WiFi access point <NUM>, to one or more beamformer devices <NUM>, e.g. WiFi client stations <NUM>, <NUM>, <NUM>, an indication of a precoder for Uplink transmission per Uplink transmission <NUM>, <NUM>, <NUM>, e.g. as described above with respect to <FIG>.

In an example, the method <NUM> comprises: Transmitting <NUM>, by the beamformee device <NUM>, a trigger frame, e.g. a trigger frame <NUM>, <NUM> as described above with respect to <FIG>, to the one or more beamformer devices, wherein the trigger frame <NUM> comprises the indication of the precoder.

In an example, the trigger frame <NUM> comprises an indication of a specific precoder per uplink transmission that is based on previously collected channel state information, wherein the specific precoder is included within the trigger frame <NUM>, e.g. as described above with respect to <FIG>.

In an example, the method <NUM> comprises: selecting, by the beamformee device <NUM>, a precoder per beamformer device <NUM> from a set of precoders produced for different uplink transmissions; and indicating the selected precoder per beamformer device <NUM> in the trigger frame <NUM>, e.g. as described above with respect to <FIG>.

In an example, the method <NUM> comprises: selecting, by the beamformee device <NUM>, a precoder per beamformer device <NUM> for different types of uplink transmissions, wherein the different types of uplink transmissions are from the following: Single-User, SU, Multiple-User, MU, Multiple-User-MIMO, or from further types of uplink transmissions, e.g. as described above with respect to <FIG>.

In an example, the trigger frame <NUM> comprises a trigger frame indication field that includes the following information <NUM>, <NUM> per beamformer device <NUM> scheduled for the next uplink transmission: precoder type indication for indicating which type of precoder to use, and precoder data for indicating precoding data, e.g. wideband precoder or codebook based precoder with Precoding Matrix Indicator, PMI, e.g. as described above with respect to <FIG>.

In an example, the precoder type indication indicates one of the following precoder types: first type: no precoder required, second type: last updated precoder to be used, third type: precoder indicated in trigger frame to be used, fourth type: precoder update will follow the trigger frame, by special precoder update frame, or further types of precoders, e.g. as described above with respect to <FIG>.

In an example, the method <NUM> comprises: transmitting, by a beamformee device <NUM>, a channel sounding announcement, e.g. a Null Data Packet Announcement, NDPA <NUM>, for prompting the beamformer devices <NUM> initiating a channel sounding procedure, and to receive a corresponding channel sounding frame, e.g. a Null Data Packet, NDP, <NUM> from the beamformer devices <NUM> responsive to the channel sounding announcement <NUM>; transmitting, by the beamformee device <NUM>, a feedback frame <NUM> to a respective channel sounding frame <NUM>, and transmitting, by the beamformee device <NUM>, two or more different feedback update frames <NUM> for updating a beamformer device <NUM> with new precoding information to the same beamformer device <NUM> based on the same channel sounding frame <NUM>.

In an example, the method <NUM> comprises: transmitting, by the beamformee device <NUM>, multiple feedback frames <NUM> between two NDPA-NDP transmissions, e.g. as described above with respect to <FIG>.

In an example, the method <NUM> comprises: computing, by the beamformee device, channel state information (CSI) from the channel sounding procedure and; assigning a precoder to a respective beamformer device based on the computed CSI information, e.g. as described above with respect to <FIG>.

In an example, the feedback update frame comprises one of the following: precoding matrices data based on previously performed channel sounding procedure, e.g. NDPA-NDP procedure, feedback type indication to allow further usage of the same precoder, e.g. as described above with respect to <FIG>.

In an example, the trigger frame comprises common information <NUM> and per user information <NUM>, e.g. as defined by <NUM>. 11ax WiFi communications standard, wherein the per user information <NUM> comprises trigger dependent user information <NUM> which indicates a precoder for Uplink beamforming, e.g. as described above with respect to <FIG>.

In an example, the trigger dependent user information <NUM> indicates to use a last updated precoding matrix by not explicitly indicating a precoding matrix, e.g. as described above with respect to <FIG>.

In an example, the trigger dependent user information <NUM> comprises a precoding matrix <NUM> to use, e.g. as described above with respect to <FIG>.

In an example, the trigger dependent user information <NUM> comprises a Precoding Matrix Index (PMI) <NUM>, to indicate a precoding matrix from a predefined codebook, e.g. as described above with respect to <FIG>.

The method <NUM> may be applied in a beamformee device, e.g. an access point <NUM> as shown in <FIG>.

Such a beamformee device <NUM>, e.g. a WiFi access point, can be used for initiating beamformed uplink transmissions of one or more beamformer devices, e.g. WiFi client stations <NUM>, <NUM>, <NUM>, e.g. as shown in <FIG>, wherein the beamformee device <NUM> is configured to: transmit to one or more beamformer devices, e.g. WiFi client stations <NUM>, <NUM>, <NUM>, an indication of a precoder for Uplink transmission per Uplink transmission, e.g. as described above with respect to <FIG>.

The present disclosure also supports a computer program product including computer executable code or computer executable instructions that, when executed, causes at least one computer to execute the performing and computing steps described herein, in particular the steps of the method <NUM> described above. Such a computer program product may include a readable non-transitory storage medium storing program code thereon for use by a computer. The program code may perform the processing and computing steps described herein, in particular the method <NUM> described above.

While a particular feature or aspect of the disclosure may have been disclosed with respect to only one of several implementations, such feature or aspect may be combined with one or more other features or aspects of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms "include", "have", "with", or other variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term "comprise". Also, the terms "exemplary", "for example" and "e.g." are merely meant as an example, rather than the best or optimal. The terms "coupled" and "connected", along with derivatives may have been used. It should be understood that these terms may have been used to indicate that two elements cooperate or interact with each other regardless whether they are in direct physical or electrical contact, or they are not in direct contact with each other.

Claim 1:
A method (<NUM>) for managing beamformed uplink transmissions from one or more beamformer devices (<NUM>), wherein the method (<NUM>) is initialized by a beamformee device (<NUM>), the method comprising:
transmitting (<NUM>), by a beamformee device (<NUM>), to one or more beamformer devices (<NUM>), an indication of a precoder for uplink transmission per uplink transmission (<NUM>, <NUM>, <NUM>);
transmitting (<NUM>), by the beamformee device (<NUM>), a trigger frame (<NUM>) to the one or more beamformer devices, wherein the trigger frame (<NUM>) comprises the indication of the precoder;
before transmitting the trigger frame, transmitting, by the beamformee device (<NUM>), a channel sounding announcement, for prompting the beamformer devices (<NUM>) initiating a channel sounding procedure, and to receive a corresponding channel sounding frame from the beamformer devices (<NUM>) responsive to the channel sounding announcement (<NUM>);
transmitting, by the beamformee device (<NUM>), a feedback frame (<NUM>) to a respective channel sounding frame (<NUM>), and
transmitting, by the beamformee device (<NUM>), two or more different feedback update frames (<NUM>) for updating a beamformer device (<NUM>) with new precoding information to the same beamformer device (<NUM>) based on the same channel sounding frame (<NUM>).