Ascertaining of user equipment precoding functionality used for uplink reference signaling

Abstract

A method (300) for at least partial ascertaining of a User Equipment (UE) precoding functionality during uplink reference signaling is provided. Performed by a network entity (e.g. gNB), the method includes ascertaining (S305) a precoding functionality used by the UE when sending uplink reference signals to the network entity, and receiving (S320) the uplink reference signals from the UE. The method may optionally include using (S330) the ascertained information as part of processing (S332) and / or storing (S334) the received signals. A corresponding method for a UE, a network entity, a UE, computer program and computer program product are also provided.

Description

ASCERTAINING OF USER EQUIPMENT PRECODING FUNCTIONALITY USED FOR UPLINK REFERENCE SIGNALING Technical field

[0001] The present disclosure relates to wireless communications such as performed in telecommunication networks. In particular, the present disclosure relates to ascertaining of a precoding functionality of a User Equipment during uplink reference signaling.

[0002] In telecommunication networks, uplink reference signaling is used to allow a receiving network entity to evaluate the quality of an uplink (UL) channel. A User Equipment (UE, such as a wireless device in form of e.g. a smartphone or similar) sends a pilot signal to the receiving network entity (such as a base station or similar), and the latter uses the received signal e.g. to determine a quality of the uplink channel, understand the current radio environment and channel conditions between the UE and network entity, and to e.g. determine what actions (such as resource allocation, scheduling decisions, etc.) the network entity may take in order to optimize the communication between the network entity and UE. For example, if the network entity is a base (transceiver) station, the base station may use the received signal to derive appropriate transmission / reception beams, to perform link adaptation (e.g. setting a modulation and coding scheme, MCS, and multiple-input multiple-output, MIMO, precoder) for a physical uplink shared channel (PUSCH) transmission, or similar. Within for example Third Generation Partnership Project (3GPP) systems such as Long Term Evolution (LTE) and New Radio (NR, also commonly referred to as Fifth Generation, 5G, telecommunication), an example of such an uplink reference signal is the sounding reference signal (SRS) that is sent from the UE to an Evolved Node B (eNB, for LTE) or a Next-Generation Node B (gNB, for NR / 5G as described in more detail in e.g.3GPP TS 38.211).

[0003] In LTE and NR, the SRS signal is configured via Radio Resource Control (RRC), and some parts of the configuration can be updated using Medium Access Control (MAC) Control Element (CE) signaling (to avoid e.g. using RRC which is slower than MAC CE). The configuration includes SRS resource allocation (i.e. whatphysical resources and sequences to use), as well as a selection between aperiodic / periodic / semi-persistent behavior. For aperiodic SRS transmission, the RRC configuration may not necessarily activate an SRS transmission from the UE, and a dynamic activation trigger may instead be transmitted via the physical downlink control channel (PDCCH)’s downlink control information (DCI) in the downlink (DL) from the (e / g)NB to order the UE to transmit the SRS once, at a predetermined time. In NR / 5G, SRS resources can for example be configured with different usages: codebook-based, wherein SRS resources in an SRS resource set configured with usage “codebook” are used to sound different UE antennas and let the gNB determine suitable precoders, rank and MCS for coming UL transmissions; non-codebook-based, wherein SRS resources in an SRS resource set configured with usage “nonCodebook” are used to sound different potential precoders autonomously determined by the UE, and wherein the gNB then select which precoders the UE should use for coming PUSCH transmissions; or e.g. with antenna switching, wherein SRS resources in an SRS resource set configured with usage “antennaSwitching” are used to sound the channel in the UL so that the gNB can use reciprocity to determine suitable DL precoders.

[0004] A UE may include several antennas (or antenna elements, which may be referred to as antenna ports), and may use different antennas for transmitting different signals. However, in contemporary standard specifications, how exactly the UE is to map each SRS signal to one or more of its multiple antennas (or antenna elements, or antenna ports) is up to the UE itself to determine, with the consequence that the network entity that receives the uplink reference signals from the UE is not aware of exactly which antenna (element / port) that was used by the UE to send each uplink reference signal. This may limit the capability of the receiving network entity of e.g. correctly drawing conclusions about the actual wireless channel response based on the received uplink reference signals, as the network entity cannot know whether e.g. a detected change in the equivalent wireless channel is due to e.g. a change of the physical environment in which the signals are sent, a change of the mapping between signals and antennas performed by the UE, or a combination of both. This may be particularly troublesome if the network entity uses e.g. Artificial Intelligence (AI) / Machine Learning (ML) in order to for example predict future uplink Channel State Information (CSI) based on one or more previously received uplink reference signals.

[0005] The present disclosure seeks to develop the use of uplink reference signaling and to mitigate the above-mentioned shortcomings thereof. Summary

[0006] To at least partially overcome some or all of the above-identified shortcomings of contemporary technology, the present disclosure provides a computer-implemented method performed by at least one network entity for at least partial ascertaining of a User Equipment (UE) precoding functionality during uplink reference signaling, a computer-implemented method performed by a UE to assist the at least one network entity in such ascertaining, a corresponding network entity, UE, telecommunications system, and corresponding computer programs and computer program products as defined in and by the accompanying independent claims. Various embodiments of the methods, network entity, UE, telecommunications system, computer programs and computer program products are defined in and by the accompanying dependent claims.

[0007] According to a first aspect, there is provided a computer-implemented method for at least partial ascertaining of a User Equipment (UE) precoding functionality during uplink reference signaling. The method is performed by at least one network entity of a telecommunications network. The method includes receiving one or more uplink reference signals from a UE. The method includes ascertaining information about at least part of a precoding functionality used by the UE to send the one or more uplink reference signals, wherein the precoding functionality defines one or more mappings between uplink reference signals and one or more antenna ports of the UE.

[0008] The present disclosure improves upon contemporary technology in that it allows to network entity to be made aware of how the precoding functionality of the UE will be configured when the UE sends the one or more uplink reference signals, by e.g. the network entity itself instructing the UE on how to perform such configuration before the sending, and / or by the network entity receiving information from the UE about how the latter is configured. Thus, the network entity may use the ascertained information in order to e.g. more accurately draw conclusions about the uplink channel quality (such as CSI), by correcting for e.g. any change in the precoding of the UE based on the ascertained information thereabout.

[0009] As used herein, and as will be further described in more detail later herein, a “precoding functionality” is how the UE maps one or more uplink reference signals to one or more of its physical antenna ports, wherein a physical antenna port may include one or more physical antenna elements.

[0010] As used herein “ascertaining” means that the network entity improves its knowledge about (i.e. becomes more aware about) how the UE is configured in terms of precoding functionality, i.e. about the precoding functionality that the UE uses (or have used) when sending uplink reference signals to the network entity. As used herein, “ascertaining” does not necessarily result in guaranteed knowledge, as the UE may still, at least in some situations and for various reasons, decide not to use a precoding functionality as at least partially indicated to the network entity. The network entity may however assume that the UE is going to act as indicated, as that is often the best the network entity can do if it is not in complete control of the UE. As will also be further exemplified later herein, after performing the method as envisaged herein, the network entity may not necessarily know exactly what precoding functionality that the UE uses, but may at least know some characteristic of the UE that was otherwise unknown, such as for example that the precoding functionality (whatever it is) of the UE will remain constant throughout a certain time period, for a certain number of uplink reference signal transmissions, or similar, based on which (partial) knowledge the network entity may more accurately e.g. analyze the uplink reference signals received from the UE. Phrased differently, ascertaining information about the precoding functionality includes at least that the network entity may gain at least some knowledge about whether a change in an uplink reference signal is due to the UE having changed the precoding functionality or whether the radio environment in which the signal was / is transmitted has changed.

[0011] In one or more embodiments of the method, the one or more uplink reference signals may be sounding reference signals (SRSs). As used herein, an SRS may be as defined and used by 3GPP for LTE and / or NR / 5G. For e.g. LTE and / or NR / 5G, an “uplink reference signal” may also be referred to as an “SRS port” or similar, and the UE map (via its precoding functionality) thus provide a mapping between SRS ports and (physical) antenna ports.

[0012] In one or more embodiments of the method, the ascertaining may include sending, before the receiving (of the one or more uplink reference signals), at least one request message to the UE indicative of the at least part of the precoding functionality to be used by the UE when sending the one or more uplink reference signals. Phrased differently, the network entity may instruct the UE on how the latter should adapt its precoding functionality before sending uplink reference signals to the network entity.

[0013] In one or more embodiments of the method, the ascertaining may include receiving at least one information message from the UE indicative of the at least part of the precoding functionality used by the UE when sending the one or more uplink reference signals. Phrased differently, the network entity may receive information from the UE informing the network entity about what precoding functionality that is or was used to send an uplink reference signal, or at least about some characteristic of the precoding functionality such as it being constant for a certain period of time, or similar.

[0014] In one or more embodiments of the method, the at least one request message may include a request for the at least part of the precoding functionality to be fixed until indicated otherwise or during one or more periods of time. This may be advantageous in that the network entity may not necessarily need to explicitly define (or gain knowledge about) e.g. how the UE should map between the uplink reference signals and its antenna ports, but still know that for at least some time, such a mapping will not change.

[0015] In one or more embodiments of the method, the at least one request message may explicitly indicate the at least part of the precoding functionality to be used by the UE when sending the one or more uplink reference signals. This may be advantageous in that the network entity may then have full control over how the UE is to map between uplink reference signals and its antenna ports.

[0016] In one or more embodiments of the method, the at least part of the precoding functionality to be used by the UE when sending the one or more uplink reference signals may be indicated in the at least one request message as an index of a precoding codebook known to both the UE and the network entity. This may be advantageous in that it e.g. reduces the amount of information needed to be transferred between the network entity and UE.

[0017] In one or more embodiments of the method, the at least one request message may include a request for the at least part of the precoding functionality to be fixed during sending of a burst of a predefined number of the uplink reference signals. This may be advantageous in that the network entity does not necessarily need to explicitly define (or gain knowledge about) e.g. how the UE should map between the uplink reference signals and its antenna ports, but still know that for at least a certain number of consecutive uplink reference signals, such a mapping will not change.

[0018] In one or more embodiments of the method, the at least one request message may include a request for the UE not to change an uplink reference signal transmission power until indicated otherwise or during one or more periods of time. This may be advantageous in that the network entity may know that a detected change in the received one or more uplink reference signals is at least not due to the UE having changing the transmission power.

[0019] In one or more embodiments of the method, the at least one request message may include a request for the UE to transmit at a maximum power or with an otherwise specified power until indicated otherwise or during one or more periods of time. This may be advantageous in that the network entity may gain more knowledge about the precoding functionality used by the UE.

[0020] In one or more embodiments of the method, the method may further include using the ascertained information about the at least part of the precoding functionality as part of processing and / or storing of the received one or more uplink reference signals. This may be advantageous in that the ascertained information may, as already mentioned, be used to at least partially eliminate uncertainties whether changes in the received signals are due to the UE / precoding functionality or the radio environment, and similar.

[0021] In one or more embodiments of the method, the processing may include estimating and / or predicting channel state information (CSI) and / or computing one or more downlink precoders based on the received one or more uplink reference signals. This may be advantageous in that in combination with the ascertained information about how the UE maps between uplink reference signals and antenna ports, such estimation, prediction and / or computing can be made more accurately / reliably.

[0022] In one or more embodiments of the method, the method may further include using a Machine Learning model trained to perform the estimating, predicting and / or computing based on the received uplink signals, with the same advantages as indicated above.

[0023] In one or more embodiments of the method, the method may further include selecting the Machine Learning model (e.g. from a plurality of available such models) based on whether the ascertained information about the at least part of the precoding functionality indicates that the UE uses time bundling for sending the one or more uplink reference signals. As used herein, “time bundling” includes methods where the receiver (i.e. network entity) leverages multiple uplink reference signal transmissions performed by the UE at different times to improve the quality of the CSI. For example, the phase (and potentially also the amplitude) of the UE transmit chains at the occasions of the different uplink reference signal transmissions may experience different levels of coherency (i.e., different levels of phase and amplitude similarity).

[0024] In one or more embodiments of the method, the storing may include storing the received one or more uplink reference signals for use as training data for a Machine Learning algorithm. This may be advantageous in that in combination with the ascertained information about the precoding functionality of the UE at the sending of each signal, the performance of the (training of the) Machine Learning algorithm may be improved, as the ascertained information may be used to e.g. compensate for thus known changes in the precoding functionality. Phrased differently, although the network entity may not necessarily directly use and process the received uplink reference signals, such data may be stored to build training data for later training of Machine Learning algorithms / models.

[0025] In one or more embodiments of the method, the method may further include sending a capability enquiry message to the UE to confirm that i) the UE is capable of adapting the at least part of its precoding functionality in accordance with a request message sent to the UE from the network entity, and / or ii) that the UE is capable of providing one or more information messages about the at least part of its precoding functionality. This may be advantageous in e.g. that the network entity then knows what to expect, and whether the information about the precoding functionality of the UE may at all be ascertained. Sending of the capability enquirymessage may preferably be performed before e.g. attempting to send the request message to the UE and / or before attempting to receive an information message from the UE.

[0026] In one or more embodiments of the method, the capability enquiry message may be or form part of a “UECapabilityEnquiry” message. This may be advantageous as such as message type is already available in e.g. LTE and NR / 5G, and in that the information about the herein envisaged capability of the UE may then be included as part of such an already existing message, e.g. by introducing one or more new / additional parameters of such a message. For example, a new parameter may be added to such a message, indicating (using e.g. Boolean) whether the UE has the desired capability to adapt and / or information of its precoding functionality or not to the receiving network entity.

[0027] In one or more embodiments of the method, the network entity may be one of a generic network node, a base (transceiver) station such as a gNB, eNB or similar, a relay node, a core network node or any other device capable of directly or indirectly communicating with the UE.

[0028] In one or more embodiments of the method, the at least one request message may include a request for the UE to indicate to the network entity whenever the at least part of the precoding functionality changes, and / or whenever a difference between a previously used precoding functionality and the precoding functionality used to send the one or more uplink reference signals exceeds a threshold value. This may be advantageous in that the network entity may then better know what to expect from the UE and the one or more uplink reference signals received therefrom, which may be used by the network entity e.g. as part of processing the received signals (during e.g. Machine Learning-based prediction of future CSI or similar).

[0029] In one or more embodiments of the method, the at least one request message may include a request for the UE to indicate to the network entity whenever the at least part of the precoding functionality has changed since receiving a previous request message from the network entity and / or during one or more previous slots of or periods of time. This may be advantageous in that the UE may only need to inform the network entity once there has been any actual change, thus reducing the amount of information sent between the network entity and the UE.

[0030] In one or more embodiments of the method, the at least one request message may include precoding weights of the precoding functionality to be used by the UE when sending the one or more uplink reference signals.

[0031] In one or more embodiments of the method, the ascertaining may include receiving at least one information message from the UE indicative of the at least part of the precoding functionality used by the UE to send the one or more uplink reference signals. Such a message is preferably received before receiving the one or more uplink reference signals, but may also be received after receiving the one or more uplink reference signals. Phrased differently, the important thing is that the network entity is at least at some point in time provided with such information. Receiving such information message may be advantageous e.g. if the UE is not capable of changing / adapting its precoding functionality as requested by a network entity, as the network entity may then still be made aware of changes to the precoding functionality performed by the UE on its own behalf.

[0032] According to a second aspect, there is provided a computer-implemented method for assisting a network entity of a telecommunications network in at least partial ascertaining of a User Equipment (UE) precoding functionality during uplink reference signaling. The method is performed by the UE. The method includes sending one or more uplink reference signals to a network entity. The method includes assisting the network entity in ascertaining at least part of a precoding functionality of the UE used to send the one or more reference signals, wherein the precoding functionality maps between uplink reference signals and physical antenna ports of the UE as described earlier herein. This method thus corresponds to what is or may be performed by the UE disclosed earlier herein with reference to the method of the first aspect.

[0033] In one or more embodiments of the method, the one or more uplink reference signals may be sounding reference signals (SRSs).

[0034] In one or more embodiments of the method, the assisting may include sending at least one (precoding) information message to the network entity indicative of the at least part of the precoding functionality used by the UE when sending the one or more uplink reference signals.

[0035] In one or more embodiments of the method, the method may (further) include keeping the at least part of the precoding functionality fixed during sending of the one or more uplink reference signals. If not due to being instructed to do so by the network entity, the method may further include informing the network entity about the precoding functionality via the at least one information message sent to the network entity.

[0036] In one or more embodiments of the method, the method may (further) include keeping the at least part of the precoding functionality fixed until indicated otherwise or during one or more periods of time (and to inform the network entity thereof via the at least one information message).

[0037] In one or more embodiments of the method, the at least one information message may include an explicit indication of the at least part of the precoding functionality used by the UE when sending the one or more uplink reference signals.

[0038] As generally envisaged herein, the UE may be configured to send the at least one information message before or after sending one or more of the uplink reference signals, as long as it is made clear to the network entity what the at least part of the precoding functionality was (or at least when / how it changed) for each of the one or more uplink reference signals.

[0039] In one or more embodiments of the method, the at least part of the precoding functionality may be indicated in the at least one information message as an index of a precoding codebook known to both the UE and network entity.

[0040] In one or more embodiments of the method, the method may (further) include keeping the at least part of the precoding functionality fixed during sending of a burst of predefined number of uplink reference signals (and e.g. informing the network entity thereof via the at least one information message).

[0041] In one or more embodiments of the method, the method may (further) include not changing an uplink reference signal transmission power until indicated otherwise or during one or more time periods (and e.g. informing the network entity thereof via the at least one information message).

[0042] In one or more embodiments of the method, the method may (further) include transmitting at a maximum power or with an otherwise specified power untilindicated otherwise or during one or more periods of time (and e.g. informing the network entity thereof via the at least one information message).

[0043] In one or more embodiments of the method, the method may (further) include using time bundling for sending the one or more uplink reference signals (and e.g. informing the network entity thereof via the at least one information message).

[0044] In one or more embodiments of the method, the method may (further) include sending a capability information message to the network entity informing the network entity that i) the UE is capable of adapting the at least part of the precoding functionality in accordance with a request message sent from the network entity to the UE, and / or ii) that the UE is capable of providing the at least one information message to the network entity.

[0045] In one or more embodiments of the method, the information message may be or form part of a UECapabilityInformation message. This may be advantageous in that such a message are already available as part of e.g. LTE and / or NR / 5G, and in that the additional information envisaged as being provided by the UE herein may thus be relayed to the network entity by introducing one or more additional / new parameters of such a message.

[0046] In one or more embodiments of the method, the method may (further) include receiving a capability enquiry message from the network entity (such as e.g. a UECapabilityEnquiry message), and sending the capability information message in response to receiving such a capability enquiry message.

[0047] In one or more embodiments of the method, the method may (further) include sending the at least one information message whenever the at least part of the precoding functionality changes, and / or whenever a difference between a previously used precoding functionality and the precoding functionality used to send the one or more uplink reference signals exceeds a threshold value. This may be advantageous in that information is only required to be transmitted to the network entity when there is an actual change of the precoding functionality, thus reducing the amount of transmitted information.

[0048] In one or more embodiments of the method, the method may (further) include sending the at least one information message whenever the at least part of theprecoding functionality changes since receiving a previous message (such as a previous request message) from the network entity and / or during one or more previous slots or periods of time. Also here the advantage may be that less information is needed to be transferred between the UE and network entity, or at least less often.

[0049] In one or more embodiments of the method, the at least one information message may include precoding weights of the precoding functionality of the UE.

[0050] In one or more embodiments of the method, the at least one information message may include a maximum phase error between different uplink reference signal transmissions within a period of time during which it is indicated by the UE (to the network entity, via e.g. the at least one information message) that the at least part of the precoding functionality is fixed. This may be advantageous in that the network entity may thus further adapt to the behavior of the UE in that it gains more information about the expected changes to the precoding functionality.

[0051] In one or more embodiments of the method, the assisting may include receiving at least one request message from the network entity indicative of the at least part of the precoding functionality to be used by the UE when sending the one or more uplink reference signals.

[0052] According to a third aspect, there is provided a network entity for a telecommunications network. The network entity includes processing circuitry and a memory. The memory stores instructions that are such that when executed by the processing circuitry, the network entity is caused to perform the steps of the method of the first aspect.

[0053] In one or more embodiments of the network entity, the instructions are further such that they cause (when executed) the network entity to perform any embodiment of the method of the first aspect described herein.

[0054] According to a fourth aspect, there is provided a User Equipment (UE) for a telecommunications network. The UE includes processing circuitry and a memory. The memory stores instructions that are such that they, when executed by the processing circuitry, cause the UE to perform the method of the second aspect.

[0055] In one or more embodiments of the UE, the instructions are further such that they (when executed) cause the UE to perform any embodiment of the method of the second aspect described herein.

[0056] According to a fifth aspect, there is provided a (telecommunications) system. The system includes the network entity of the third aspect (or any embodiment thereof described herein), and the UE of the fourth aspect (or any embodiment hereof described herein).

[0057] According to a sixth aspect, there is provided a computer program for a network entity (such as the network entity of the third aspect). The computer program includes computer code. The computer code is such that it, when run on processing circuitry of the network entity, causes the network entity to perform the method of the first aspect (or any embodiment thereof described herein).

[0058] According to a seventh aspect, there is provided a computer program product. The computer program includes the computer program of the sixth aspect, and a computer-readable storage medium on which the computer program is stored.

[0059] According to an eight aspect, there is provided a computer program for a User Equipment (UE, such as the UE of the fourth aspect). The computer program includes computer code. The computer code is such that it, when run on processing circuitry of the UE, causes the UE to perform the method of the second aspect (or any embodiment thereof described herein).

[0060] According to a ninth aspect, there is provided a computer program product. The computer program product includes the computer program of the eight aspect, and a computer-readable storage medium on which the computer program is stored.

[0061] As used herein, a computer-readable storage medium (such as that of e.g. the seventh or ninth aspect) may e.g. be non-transitory, and be provided as e.g. a hard disk drive (HDD), solid state drive (SDD), USB flash drive, SD card, CD / DVD, and / or as any other storage medium capable of non-transitory storage of data. In other embodiments, the computer-readable storage medium may be transitory and e.g. correspond to a signal (electrical, optical, mechanical, or similar) present on e.g. a communication link, wire, or similar means of signal transferring.

[0062] Other objects and advantages of the present disclosure will be apparent from the following detailed description, the drawings and the claims. Within the scope of the present disclosure, it is envisaged that all features and advantages described with reference to e.g. the method of the first aspect are relevant for, apply to, and may be used in combination with also the method of the second aspect, the network entity of the third aspect, the UE of the fourth aspect, the system of the fifth aspect, and the various computer programs and computer program products of the sixth to ninth aspects, and vice versa. Brief description of the drawings

[0063] Exemplifying embodiments will be described below with reference to the accompanying drawings, of which: Figure 1 schematically illustrates an AI / ML-based model for predicting CSI based on previous equivalent wireless channel observations; Figures 2A, 2B, 2C and 2D schematically illustrate various example signaling schemes between a network entity (gNB) and User Equipment (UE) according to the present disclosure; Figure 3 schematically illustrates a flowchart of various examples of a method of ascertaining information about UE precoding functionality according to the present disclosure; Figure 4 schematically illustrates a flowchart of various examples of a method of a UE assisting a network entity in ascertaining information about UE precoding functionality according to the present disclosure; Figures 5A and 5B schematically illustrate example network entities according to the present disclosure; Figures 6A and 6B schematically illustrate example UEs according to the present disclosure, and Figure 7 schematically illustrates example computer program products, computer programs and computer-readable storage media according to the present disclosure.

[0064] In the drawings, like reference numerals will be used for like elements unless stated otherwise. Unless explicitly stated to the contrary, the drawings show only such elements that are necessary to illustrate the examples, while other elements, in the interest of clarity, may be omitted or merely suggested. Detailed description

[0065] In what follows, SRS will be used as an example of an uplink reference signal, and a gNB will be used as an example of a network entity that receives such an uplink reference signal from a UE. It should be noted however that what is described herein apply also to other types of uplink reference signals and also for other types of network entities than gNBs.

[0066] Using a single time / frequency resource element for simplicity, a gNB with^^^^ antennas receives an SRS ^^^^(^^^^) ∈ ℂ^^^^×1 at an arbitrary time instance ^^^^ from one UESRS port. The received SRS may be expressed as ^^^^(^^^^) = ^^^^(^^^^)^^^^(^^^^)^^^^(^^^^) + ^^^^(^^^^), (1)denotes the wireless channel response at time ^^^^, where ^^^^(^^^^) ∈ℂ^^^^×1denotes the SRS precoder characterizing the mapping from the UE SRS port to the UE antenna elements (also referred to as physical antenna ports) at time ^^^^, where^^^^(^^^^) denotes the transmitted SRS, where ^^^^(^^^^) ∈ ℂ^^^^×1 is thermal noise, and where ^^^^ isthe number of antenna elements of the UE. As ^^^^(^^^^) is usually not known by the gNB, the above expression may be rewritten aswhere ^^^^ (^^^^) = ^^^^( ) ^^^^×1^^^^^^^^ ^^^^ ^^^^(^^^^) ∈ ℂ represents an equivalent wireless channel that isobserved by the gNB.

[0067] As used herein, an (SRS) precoder or precoding functionality refers to a mapping between one or more SRSs (or similar uplink reference signals, such as envisaged in e.g. sixth generation, 6G, telecommunication) and one or more physical antenna ports of the UE. It should be noted that a physical antenna port may include one or more physical antenna elements. The mapping may for example be describedwith an equation ^^^^ = ^^^^^^^^, where ^^^^ is a vector with a length equal to the number ofphysical antenna ports (^^^^), where ^^^^ is another vector with a length equal to thenumber of SRSs that the UE shall transmit (an integer ^^^^), and where ^^^^ is a precodingmatrix with dimensions (^^^^ × ^^^^). For example, the UE may use an SRS precoderto map a first SRS to a first physical antenna port, and a second SRS to a second physical antenna port, or similar.

[0068] So-called SRS-based time bundling may be used to describe various methods where the receive (e.g., the gNB) leverages multiple SRS transmissions performed by a UE at different times in order to improve the quality of the CSI. As mentioned earlier herein, the phase (and potentially also the amplitude) of the UE transmit chains at the occasions of the different SRS transmissions may experience different levels of coherence (such as different levels of phase and / or amplitude similarity).

[0069] Artificial Intelligence (AI) and Machine Learning (ML) have been investigated as promising tools to optimize the air interface design in wireless communication networks within both academia and industry. Example use cases include using autoencoders for CSI compression in order to reduce the feedback overhead and improve channel prediction accuracy; using deep neural networks for classifying line-of-sight (LOS) and non-line-of-sight (NLOS) conditions in order to enhance positioning accuracy; and e.g. using reinforcement learning (RL) for beam selection at the network side and / or at the UE side in order to reduce signaling overhead and beam alignment latency, as well as using deep RL in order to learn an optimal precoding policy for complex MIMO precoding problems.

[0070] In the 3GPP NR standardization work, a Release 18 study item (SI) on AI / ML for NR air interface has been initiated already (see e.g. RP-213599, “Study on Artificial Intelligence (AI) / Machine Learning (ML) for NR Air Interface”, Dec.2021. New 3GPP study item for Rel.18). This study item explores potential benefits of augmenting the air interface with features enabling improved support of AI / ML- based algorithms for enhanced performance and / or reduced complexity / overhead. By studying a few selected use cases (CSI feedback, beam management and positioning), this SI aims at laying a foundation for future air interface use cases leveraging AI / ML techniques.

[0071] Figure 1 schematically illustrates on AI / ML-based example 100, wherein one or more AI / ML models 110 leverages SRS-based time bundling to, e.g., provide accurate estimations / predictions of the CSI and / or downlink precoding weights. For example, based on observed equivalent wireless channels ^^^^^^^^^^^^at one or more earliertime instances ^^^^ − ^^^^, … , ^^^^ − 1, the one or more AI / ML models 110 are trained topredict what the next equivalent wireless channel ^^^^^^^^^^^^will be at time instance ^^^^, i.e. the AI / ML model(s) 110 is / are trained to estimate a function ^^^^ that provides anestimate ^�^^^^^^^^^^^(^^^^) of ^^^^^^^^^^^^(^^^^) asThe one or more AI / ML models 110 may in other examples be trained to estimate e.g.^�^^^(^^^^) based on earlier estimates ^�^^^(^^^^ − 1), … instead of observations ^^^^(^^^^ − 1), …, orsimilar.

[0072] Techniques such as illustrated in Figure 1 have been shown capable of e.g. providing enhanced communication performance when compared to advanced non- AI / ML signal processing techniques such as e.g. Kalman filtering (see e.g. H. Lee, J. Jeong and Z. Wang, "Deep Learning for Wireless Dynamics", 2022 IEEE International Conference on Communications Workshops (ICC Workshops), pp. 1141-1146, 2022).

[0073] As will now be described in more detail, a problem with contemporary such technology is that according to the current standard specification, how each SRS port (i.e. each uplink reference signal) should be mapped to each UE antenna (element) is up to the UE to decide, and thereby not known to the network entity (such as the gNB) receiving the uplink reference signal. This poses a problem for SRS-based channel prediction techniques designed via AI / ML models that leverage SRS-based time bundling (such as illustrated and description with reference to Figure 1). More concretely, based on equation (1), the equivalent wireless channel ^^^^^^^^^^^^(^^^^) observed by the gNB for a given SRS transmission may be notably different from thatobserved for a previous SRS transmission (i.e. different from ^^^^^^^^^^^^(^^^^ − ^^^^)), even when ^^^^and (^^^^ − ^^^^) are in close proximity, due to the fact that an (for the gNB) uncontrolledchange of the SRS precoder ^^^^ between time instances ^^^^ and (^^^^ − ^^^^), as ^^^^(^^^^) may be(very) different from ^^^^(^^^^ − ^^^^). As a consequence, the AI / ML-models – or any othermodels that leverage SRS-based time bundling – may not be effective, as the need to leverage for example time-correlation exhibited by the wireless channel both during model training and during model inference in order to enhance their predictions.

[0074] It will now be described how the present disclosure proposes to overcome these issues with contemporary technology.

[0075] The present disclosure proposes to introduce a signaling between the gNB (i.e. network entity) and UE that enables the gNB to either control at least part of the precoding functionality (i.e. ^^^^(^^^^)) of the UE or at least receive messages indicative of what the precoding functionality used by the UE when sending one or more SRSs (i.e. uplink reference signals) is. By so doing, i.e. by ascertaining information about at least part of the used precoding functionality, the gNB is given a better chance of more accurately interpreting the SRSs it observes, and to account for e.g. sudden changes in the precoding functionality ^^^^ in an improved way.

[0076] One example embodiment of such signaling will now be described in more detail with reference to Figures 2A, 3 and 4. Figure 2A schematically illustrates an envisaged example signaling scheme 200 between a network entity / gNB 210 and UE 220 in a wireless communications system 230 (such as a telecommunications system, as also envisaged herein). Figure 3 schematically illustrates a flowchart of one or more examples of a method 300 performed by the network entity / gNB 210, and Figure 4 schematically illustrates a flowchart of one or more examples of a method 400 performed by the UE 220.

[0077] As part of an operation S305 of an example method 300, the gNB 210 ascertains information about a precoding functionality used by the UE 220 when sending SRSs. As part of an operation S405 of an example method 400, the UE 220 assists the network entity 210 in such ascertaining. The operations of ascertaining and assisting S305 and S405, respectively, are performed by the gNB 210 and the UE 220 exchanging one or more messages 241, examples of which will be given further below. As part of an operation S420 of the method 400, the UE 220 sends the one or more SRSs 250 to the gNB 210, and the gNB 210 receives the one or more SRSs 250 from the UE 220 as part of an operation S320 of the method 300. As will be described in more detail later herein, as part of an optional operation S330 of the method 300, the gNB 210 may then optionally use the ascertained information as part of a processing and / or storing of the received SRSs 250.

[0078] One example of how to perform the respective ascertaining and assisting operations S305 and S405, respectively, will now be explained in more detail with reference also to Figure 2B.

[0079] Figure 2B schematically illustrates an example signaling scheme 201 illustrating alternative examples of signaling between the gNB 210 and UE 220 as part of alternative embodiments of the respective methods 300 and 400.

[0080] As part of an operation S310 of the method 300, the gNB 210 sends at least one request message 240 to the UE 220. The message 240 indicates at least part of the precoding functionality (i.e. at least part of ^^^^(^^^^)) that the gNB 210 wants the UE 220 to use when sending one or more SRSs to the gNB 210. Sending of the at least one request message 240 (operation S310) may form part of (or constitute) the ascertaining operation S305 shown in Figure 2A.

[0081] As part of an operation S410 of the method 400, the UE 220 receives the at least one request message 240 from the gNB 210 (network entity, denoted “NE” in Figure 4), and adapts (as part of an operation S412 of the method 400) its precoding functionality in accordance with what is indicated in the at least one request message 240. Receiving the at least one request message 240 (operation S410) and adapting (operation S412) the precoding functionality in accordance therewith may form part of (or constitute) the assisting operation S405 shown in Figure 2A. After having done so, as part of the operation S420 of the method 400, the UE 220 sends one or more SRSs (i.e. uplink reference signals) 250 to the gNB 210 using the adapted precoding functionality.

[0082] In this way, the UE 220 assists the gNB 210 by enabling the latter to ascertain information about at least part of the precoding functionality used by the UE 220, by the gNB 210 commanding (via the message 240) the UE 220 how the latter should configure its precoding functionality before sending reference signals 250 back to the gNB 210.

[0083] As part of the operation S320 of the method 300, the gNB 210 receives the one or more SRSs 250 from the UE 220. As part of the optional operation S330 of the method 300, the gNB 210 then uses the now ascertained information about the at least part of the precoding functionality of the UE 220 as part of a processing (as part of an operation S332 of the method 300) and / or storing (as part of an operation S334of the method 300) of the received one or more SRSs 250 (and e.g. of the ascertained information, in case of e.g. storing).

[0084] In this particular example, the gNB 210 commands the UE 220 what the latter should do with its precoding functionality (i.e. with ^^^^(^^^^)). Another envisaged example will now be explained with reference also to Figure 2C, which schematically illustrates an alternative signaling scheme 202 between the gNB 210 and UE 220.

[0085] Here, as part of an operation S430 of the method 400, the UE 220 sends at least one information message 252 to the gNB 210, wherein the at least one information message 252 indicates partly or fully what precoding functionality the UE 220 will use when sending SRSs to the gNB 220. The at least one information message 252 is received by the gNB 210 as part of an operation S340 of the method 300. It is noted that only one of, or both of, the operations S310 and S430 (and corresponding operations S410 and S340, respectively) may be performed, e.g. it may also be the case that there are both request messages 240 and information messages 252 exchanged between the gNB 210 and UE 220, etc. Receiving the at least one information message 252 (operation S340) may for part of (or constitute) the ascertaining operation S305 shown in Figure 2A.

[0086] As part of an operation S432 of the method 400, the UE 210 configures / adapts its precoding functionality in accordance with what was indicated in the information message 252, and then (as part of the operation S420 of the method 400) sends the one or more SRSs 250 to the gNB 210 (which receives the one or more SRSs 250 as part of the operation S320 of the method 300, and then proceeds with using the so ascertained knowledge / information about the (at least part of the) precoding functionality of the UE 220 as part of the operation S330 of the method 300, etc. Sending the at least one information message 252 (operation S430) and adapting the precoding functionality (operation S432) may form part of (or constitute) the assisting operation S405 shown in Figure 2A.

[0087] In this particular example, it is thus not the gNB 210 that controls the UE 220, but the UE 220 instead informs the gNB 210 about what the precoding (or part thereof) functionality used to send the SRSs 250 will be.

[0088] It should be noted that the exact order of the operations shown in Figures 3 and 4 in relation to Figures 2A, 2B and 2C are not important. For example, theascertaining operation S305 may be performed by the gNB 210 both before and after receiving the one or more SRSs 250 from the UE 220, at least if including receiving the one or more information messages 252 (operation S340). Likewise, the assisting operation S405 may be performed by the UE 220 both before and after sending the one or more SRSs 250 to the gNB 210, at least if including sending the one or more information messages 252 (operation S430). For example, it is envisaged that the SRSs 250 may be sent from the UE 220 to the gNB 210 before the information message 252 is sent, as long as the information message 252 is then sent in due time to the gNB 210 such that the gNB 210 is able to ascertain what (the at least part of) the precoding functionality of the UE 220 was when the UE 220 sent the SRSs 250. For example, in such an alternative embodiment, in method 400 operation S430 may be performed after operation S420, and in method 300 operation S340 may be performed in between operations S320 and S330. Generally herein, the order of any described operations is not important as long as the desired result remains the same, i.e. as long as information is available to the gNB 210 (and / or to the UE 220) before such information is supposed to be used and / or acted upon.

[0089] Yet other examples of signaling between the gNB 210 and UE 220 will now be described with reference also to Figure 2D. Figure 2D schematically illustrates one or more alternative signaling schemes 203. Here, as part of an operation S350 of the method 300, the gNB 210 sends a capability enquiry message 242 to the UE 220 (which receives the enquiry as part of an operation S440 of the method 400). The UE 220 responds by sending (as part of an operation S442 of the method 400) a capability information message 254 back to the gNB 210 (which receives the capability information message 254 as part of an operation S352 of the method 300). The signaling 202 may then continue in accordance with any of Figures 2A, 2B and 2C. For example, if the capability information message 254 indicates that the UE 220 is capable of receiving request messages 240 from the gNB 210, the gNB 210 may respond by sending such a request message 240 to the UE 220 as already described with reference to Figure 2B. Likewise, if the capability information message 254 indicates that the UE 220 is capable of sending information messages 252 to the gNB 210, the UE 220 may proceed by sending at least one such information message 252 to the gNB 210 as already described with reference to Figure 2C. Although not shown in Figure 2D, in response to receiving information that the UE 220 is capable of sending information messages 252, the gNB 210 may respond by sending a messageincluding a request for the UE 220 to send such messages, upon the receival of which the UE 220 may start sending the at least one information message 252, and similar. In any situation, sending of either the request message 252 from the gNB 210 to the UE 220, or the information message 254 from the UE 220 to the gNB 210, will enable the gNB 210 to ascertain the information about at least part of the precoding functionality used by the UE 220 as described earlier herein. The signaling 202 may then continue with the UE 220 sending the one or more SRSs 250 to the gNB 210, and with the gNB 210 acting accordingly in response to receiving such one or more SRSs 250 as described earlier herein.

[0090] In some examples, acting upon a request message 240 received from the gNB 210 may be mandatory for the UE 220, i.e. the UE 220 is forced to configure its precoding functionality in accordance with the content of the received request message 240. In other examples, the UE 220 may decide whether or how to act upon receiving the request message(s) 240. For example, the UE 220 may respond by still configuring its precoding functionality on its own, but start sending the one or more information messages 252 in order to information the gNB 210 about what is going on, in order for the gNB 210 to still receive some guidance on how to more accurately e.g. draw conclusions from its observed equivalent wireless network channel ^^^^^^^^^^^^(^^^^), and similar. In other examples, the UE 220 may decide not to do anything, in which case the gNB 210 will not benefit from the envisaged ascertaining of knowledge / information. In some examples, the UE 220 may at least, using signaling, inform the gNB 210 that the UE 220 will continue control of the precoding functionality solely on its own, without sending of any information messages 252 (which may still be useful for the gNB 210 in that it then at least knows what to expect and may select how to analyze the receive SRSs accordingly). As an example, the UE 220 may decide not to e.g. use the gNB-provided recommendation / request for a particular precoding functionality if not deemed suitable based on e.g. a latest estimate of the wireless channel (e.g. as a result of the UE rotation having changed, or similar).

[0091] In some examples, the capability enquiry message(s) 242 may include a request from the gNB 210 to the UE 220 to indicate (e.g. as part of a capability information message 254) one or more preferred / recommended values / configurations of the precoding functionality for e.g. a certain period of time(or periods of time), and similar, or the UE 220 may inform the gNB 210 about such preferences without first receiving a capability request message 242. In such a situation, the gNB 210 may then take this information from the UE 220 into account when later sending the one or more request messages 240 to the UE 220. Phrased differently, the UE 220 may be configured to communicate to the gNB 220 any information that may help the gNB 210 when attempting to control the precoding functionality of the UE 220.

[0092] As a further example, as part of e.g. a capability information message 254, the UE 220 may inform the gNB 210 that it has the capability to both receive and act upon request messages 240 and to send information messages 252, optionally also with an included preference for one or the other, and the gNB 210 may be configured to act accordingly.

[0093] As a further example, some part of the request to control the precoding functionality of the UE 220 sent by the gNB 210 may be mandatory, while other parts of the request may be optional to follow for the UE 220. Likewise, if the UE 220 decides not to follow everything of a request from the gNB 220, the UE 220 may in some examples communicate to the gNB 210 what parts of the request it intends to follow (or did follow) and which parts it does not indent to follow (or did not follow), and similar.

[0094] As a further example, a capability information message 254 may not necessarily include an explicit indication about e.g. whether the UE 220 is capable of doing this or that, but may instead e.g. include a reference to a particular standard that the UE 220 supports / is configured in accordance with, such that the gNB 210 may on its own deduce the capabilities of the UE 220 by turning to what is defined / specified as the requirements for complying with such a standard. In other examples, the gNB 210 may assume that the UE 220 is standard-compliant, and if there is a mandatory requirement for the UE 220 to be able to e.g. be controlled by request messages 240 and / or to transmit information messages 252, sending of an capability enquiry message 242 may never be needed. Likewise, the standard may indicate what information the UE 220 needs to provide upon reception of a request, while in other examples the gNB 210 may explicitly indicate the information that the UE 220 should provide upon reception of the capability enquiry message / request 242.

[0095] As a further example, the capability request message(s) 242 may include an instruction for the UE 220 to report back to the gNB 210 whether it can dynamically update its precoding functionality and also whether it can send information messages 252 informing the gNB 210 of when such updating has taken place (or will take place), all in order for the gNB 210 to improve its possibilities of accurately interpreting the received SRSs even when the precoding functionality of the UE 220 changes between different SRS transmissions.

[0096] As envisaged herein, request and / or information messages, as well as capability enquiry / information messages may be provided in multiple different ways, depending on e.g. how the relevant standard is written. For example, it is envisaged to use e.g. system information blocks (SIBs) or a signaling with a similar functionality in other specifications, and / or e.g. RRC messages, MAC control elements (CE), L1 messages (e.g. a downlink control information message), or similar when suitable.

[0097] For example, a capability enquiry message may be or form part of a UECapabilityEnquiry message in accordance with e.g.3GPP TS 38.331, by modifying the definition of such a message to include one or more additional fields and / or parameters (such as one or more attributes) in order to convey the information necessary for such an enquiry. As another example, similarly, a capability information message may be or form part of a (modified) UECapabilityInformation message in accordance with e.g.3GPP TS 38.331.

[0098] Examples of how the UE 220 may indicate that its precoding functionality may be controlled by the gNB 210, and of how the gNB 210 may control (the at least part of) the precoding functionality of the UE 220, or both, will now be given.

[0099] In some examples, the UE 220 may indicate to the gNB 210 that the precoding functionality is always fixed, or should preferably always be fixed, and e.g. act accordingly by fixing the precoding functionality until indicating otherwise to the gNB 210. In some examples, the gNB 210 may correspondingly request that the precoding functionality of the UE is always kept fixed.

[0100] In some examples, the UE 220 may indicate to the gNB 210 that the precoding functionality should (preferably, according to the UE 220) be fixed for a certain period or periods of time. The duration of such fixing may for example be indicated in terms of system frame numbers (SFNs), subframes, slots, symbols,seconds, milliseconds, and specified e.g. as from the reception of the message or from a point in time after the reception of the message specified by e.g. a relevant standard. In some examples, the UE 220 may indicate that the period or periods of time where the precoding functionality should be fixed is equal to zero, i.e., the UE 220 may recommend the gNB 210 not to control the precoding functionality. In some examples, the gNB 210 may correspondingly instruct the UE 220 to keep the precoding functionality fixed for such certain period or periods of time.

[0101] In some examples, the UE 220 may indicate to the gNB 210 a maximum time it can maintain a same precoding functionality. In some examples, the UE 220 may indicate to the gNB 210 a maximum phase error between different SRS transmissions within the period of time where the precoding functionality should(preferably) be fixed. For example, in case the UE 220 is to apply a precoder ^^^^ =(1, 0; 0, 1), then due to phase error the actual precoder may be written aswhere ^^^^1and ^^^^2are the phase errors for the respective physical antenna port. For example, if the UE 220 reports a maximum phase error of 40∘, then the UE 220 may / should be capable of keeping e.g. |^^^^1| and |^^^^2| smaller than 40∘within the indicated maximum time period. In some examples, different maximum phase errors may be reported for different time periods during which the UE 220 (preferably) has a fixed precoding functionality. For example, the UE 220 may indicate a maximum phase error of 20∘for a time period of e.g.1 second, and a maximum phase error of 40∘for a time period of 2 seconds, etc. In some examples, the gNB 210 may correspondingly instruct the UE 220 about what phase error limitations that should be used, and for what period or periods of time these should apply.

[0102] In some examples, the precoding functionality may remain fixed during time windows and be different for different time windows. The duration and starting point of each such time window may be indicated in e.g. SFNs, subframes, slots, symbols, seconds, milliseconds, or similar. The UE 220 may for example inform the gNB 210 about such a capability (or preference), and / or the gNB 210 may correspondingly instruct the UE 220.

[0103] In some examples, the precoding functionality (e.g. as preferred by the UE 220 and / or as instructed by the gNB 210) may be indicated as an index of a precodingcodebook that is known to both the gNB 210 and the UE 220. Such precoding codebooks may be identical to, or at least form a subset of, the codebook used for e.g. PUSCH data transmissions, or similar. In some examples, only the precoders associated with non-coherent UEs may be indicated, i.e. such as antenna selection precoders. As an example, a new parameter may be added per SRS resources or SRS resource set as specified in SRS config IE in 3GPP TS 38.331 (or any similar standard), where the new parameter may indicate a precoder index to be used for the SRS ports belonging to that SRS resource or SRS resource set.

[0104] In some examples, the UE 220 may indicate to the gNB 210 that it is capable of using a same precoding functionality for a number ^^^^ of consecutive SRS / uplink reference signal transmissions, and the gNB 210 may act accordingly. Phrased differently, the UE 220 may use a same precoding functionality for a burst of ^^^^ transmissions, although the UE 220 may be allowed to e.g. change its precoding functionality between such bursts. Likewise, in some examples, the gNB 210 may correspondingly instruct the UE 220 to perform such bursts. For example, in some examples, a new parameter may be added per SRS resource or SRS resource set as specified in SRS config IE in 3GPP TS 38.331 (or a similar specification), where the new parameter indicates the number ^^^^.

[0105] If the UE 220 e.g. indicates to the gNB 210 that it is capable of dynamically changing its precoding functionality, the UE 220 may (e.g. upon request from the gNB 210) inform the gNB 210 about a rate at which the precoding weights are changed. For example, if the precoding functionality-changes are periodic or aperiodic and, if aperiodic, also indicate a time between two computations of precoding weights and a starting time, and similar. Likewise, in some examples, the gNB 210 may accordingly instruct the UE 220 to use such rates, times, and similar. As an example, one or more new parameters may be added per SRS resource or SRS resource set as specified in SRS config IE in 3GPP TS 38.331 (or a similar specification), where the one or more new parameters indicate e.g. the start and lengths of time periods where the UE 220 should / intends to have a fixed precoding functionality for the SRSs configured in these SRS resources or SRS resource sets.

[0106] If the UE 220 has the capability to dynamically change its precoding functionality as well as reporting thereof, the UE 220 may inform (via e.g. an information message 252) the gNB 210 whenever a new precoding functionality (oran updated precoding functionality) is used. In some envisaged examples, the UE 220 may be configured with a dedicated physical uplink control channel (PUCCH)- scheduling request resource which the UE 220 may user to indicate that it has e.g. changed (or intends to change) the precoding functionality for one or more SRSs (e.g. one or more sets of SRSs, such as for an SRS resource, an SRS resource set, and similar). Other alternatives are of course also possible. In some examples, upon e.g. request from the gNB 210, the UE 220 may be configured to only inform the gNB 210 whenever a difference (e.g. in a Frobenius norm) between the new precoding functionality and e.g. a previously reported / indicated precoding functionality exceeds a given threshold (value). Such a threshold (value) may for example be indicated by the gNB 210 to the UE 220, be autonomously by the UE 220, and / or e.g. be defined in some applicable standard.

[0107] If the UE 220 is capable of both dynamically changing its precoding functionality and informing the gNB 210 thereof, in some examples, e.g. upon request from the gNB 210, the UE 220 may be configured to inform (via e.g. sending of an information message 252) the gNB 210 about the SRS precoding weights when the UE 220 changes them. For example, in some examples, the UE 220 may be provided / configured with a dedicated PUCCH-scheduling resource which the UE 220 may use to indicate to the gNB 210 that it has changed the SRS precoder for one or more SRSs (e.g. for an SRS resource, SRS resource set, etc.). In this case, the PUCCH- scheduling request may also trigger e.g. an UL MAC-CE or UL RRC message where the UE 220 may indicate the selected new precoding functionality / precoder.

[0108] In some examples, the gNB 210 may send a request message 240 at a time ^^^^2to the UE 220 indicating to signal whether the precoding functionality has been modified with respect to the precoding functionality that was used by the UE 220when receiving a previous request message 240 at a time< ^^^^2. For example, thegNB 210 may not request for the UE 220 to actively report the precoding functionality changes whenever they occur, but instead query the UE 220 so that the latter indicates whether the precoding functionality (configuration) has changed with respect to the last query made by the gNB 210. In some examples, the gNB 210 may request for the UE 220 to indicate the new precoding weights if they have changed since the last query. Alternatively or in addition, the gNB 210 may request e.g. for the UE 220 to indicate whether the precoding functionality has been changed in theprevious ^^^^ slots (or similar), where ^^^^ is an integer that may be, for example, a single specified value or a range of values, or similar. Alternatively or in addition, the gNB 210 may request for the UE 220 to indicate whether the precoding functionality has changed within a certain time interval (e.g. as defined by a start time and an end time), where e.g. the end time may be the current SRS occasion.

[0109] In some examples, the UE 220 may inform the gNB 210 that it has the capability of dynamically changing its precoding functionality, but that it does not have the capability of sending information messages 252 to the gNB 210. In other examples, the UE 220 may inform the gNB 210 that it has the capability of dynamically changing its precoding functionality and also the capability of sending information messages 252 to the gNB 210, but only in an aperiodic manner (e.g., it could be only when the UE 220 deems that the wireless channel has changed sufficiently and the use of a different precoding functionality will provide better performance, or similar). In other examples, the UE 220 may inform the gNB 210 that it has the capability of doing both things in a periodic manner, such as e.g. keeping the precoding functionality fixed during time windows and / or for a certain amount of SRS transmissions, and possibly changing the precoding functionality between time windows. In other examples, the UE 220 may inform the gNB 210 that at least the precoding weights used in its precoding functionality are always fixed, or at least fixed during time windows or similar.

[0110] In some examples, the UE 220 may inform the gNB 210 about what different types / configurations of precoding functionalities that it may use (or supports). This may be e.g. all or a subset of all precoders from a codebook of SRS precoders, or similar.

[0111] In some examples, the gNB 210 may not instruct the UE 220 to use a particular precoding functionality, but instead instruct the UE 220 to use a precoding functionality of its own choice as long as the precoding functionality is fixed for e.g. a specific period of time, or until indicated otherwise by the gNB 210. This may also occur e.g. in response to the UE 220 informing the gNB 210 that it is not desirable for the gNB 210 to control the precoding functionality of the UE 220.

[0112] In some examples, the UE 220 may inform the gNB 210 that it prefers to receive an explicit definition of what precoding functionality (or part of the precodingfunctionality) to use, and the gNB 210 may request for the UE 220 to use such an explicit (part of the) precoding functionality.

[0113] In some examples, the UE 220 may inform the gNB 210 that it will not change the SRS uplink transmission power e.g. until indicated otherwise or for one or more specified time periods, and / or the gNB 210 may instruct the UE 220 to do so.

[0114] In some examples, the UE 220 may inform the gNB 210 that it will transmit at maximum power or at an otherwise specified power, and / or the gNB 210 may instruct the UE 220 to do so. Here, “power” may refer to e.g. the transmit power of each physical antenna port or the aggregate transmit power of multiple or even all physical antenna ports.

[0115] In summary of all of the above, it is concluded that as envisaged herein, the UE 220 may both act on its own and inform the gNB 210 about changes it makes to the precoding functionality, and / or the gNB 210 may actively attempt to control the UE 220 to behave (with regards to what precoding functionality it uses) in a certain way. This duality applies to all examples given herein, e.g. if it is mentioned that the UE 220 may e.g. do, or prefer to do, something, it may also be such that this something is requested from the UE 220 by the gNB 210. Likewise, if it is mentioned herein that something is requested from the UE 220 by the gNB 210, it may also be such that the UE 220 on its own decides to do this something, and e.g. informs the gNB 210 that it has done, or will do, this something.

[0116] As mentioned earlier herein, the network entity (e.g. gNB 210) may use the received uplink reference signals (e.g. SRSs) together with the ascertained information about the precoding functionality used by the UE 220 to transmit these signals in order to e.g. perform predictions of future such signals, which may be advantageous in that the network entity 210 may then perform e.g. beamforming or adapt one or more other parameters related to a DL transmission to the UE 220 in advance, such that the network entity 210 is more ready once / if the UE 220 e.g. moves to a position where the radio environment is such that it behaves as predicted by the network entity 210. This may e.g. be performed by using an AI / ML-based model or models as described with reference to Figure 1, where the added knowledge about what type of, or at least what overall behavior of, the precoding functionality used by the UE 220 to transmit the uplink reference signals improves the odds of the network entity 210 making more accurate such predictions. For example, the networkentity 210 may use the ascertained information and the received uplink reference signals to make predictions of future CSI and similar. The network entity 210 may also (instead or in addition) be configured to e.g. estimate CSI, e.g. not predict future CSI but instead more accurately estimate current CSI due to having the ascertained information about the (part of the) precoding functionality of the UE 220. Alternatively, or in addition, the network entity 210 may use such data for e.g. computing one or more downlink precoders that it can use for further transmissions to the UE 220, and similar.

[0117] In some examples, the network entity 210 may use the ascertained information in order to determine whether to e.g. use one model (AI / ML-based or others) or another, or whether it is useful to attempt such modelling at all based on the information at hand. The network entity 210 may for example determine that there is not sufficient information available about the behavior of the precoding functionality of the UE 220 to perform any modeling, or it may determine that e.g. one available (AI / ML) model is more suitable than another available model, and similar.

[0118] For example, if the UE 220 indicates (or is request such) that the precoding functionality is fixed, the network entity 210 may decide to always activate e.g. a model that performs CSI estimation / prediction based on SRSs or a model that directly computers one or more downlink precoders based on SRSs. As another example, if the UE 220 sporadically changes its precoding functionality and informs the network entity 210 when such changes are performed but does not inform the network entity 210 about e.g. the uplink precoding weights used when performing such changes, the network entity 210 may decide to activate e.g. a model that performs CSI estimation / prediction based on SRSs or a model that directly computers one or more downlink precoders based on SRSs only when a sufficient number of consecutive SRS transmissions with a same precoding functionality are received. As yet another example, if the UE 220 sporadically changes the precoding functionality and informs the network entity 210 thereof and also informs the network entity 210 about the selected uplink precoding weights used when performing such changes, the network entity 210 may decide to always activate a model that performs CSI estimation / prediction based on SRSs or a model that directly computes one or more downlink precoders based on SRSs, as the knowledgeof the precoding functionality may be utilized by the network entity 210 as an input of the model (e.g. the impact of the precoding functionality may be removed by forexample performing matrix inversion, e.g. ^^^^(^^^^) may be extracted from ^^^^^^^^^^^^(^^^^) =^^^^(^^^^)^^^^(^^^^) once ^^^^(^^^^) is known,

[0119] As also described herein, the network entity 210 may actively instruct the UE 220 to e.g. fix its precoding functionality, thus enabling a continuous activation of a model for CSI estimation / prediction and / or downlink precoder-computing based on SRSs, and similar. The network entity 210 may alternatively e.g. instruct the UE 220 to sporadically change its precoding functionality, and chose to active such model or models only once a sufficient number of consecutive transmissions with a same precoding functionality are received, and similar.

[0120] Generally herein, it should be noted that the ascertained information about the precoding functionality used to send the uplink reference signals, as well as the received (and stored) uplink reference signals themselves may be utilized in a similar manner also by an entity that does not receive the uplink reference signals itself, but that are provided with this information from e.g. a gNB or similar. Consequently, when refereeing herein to a network entity “receiving one or more uplink reference signals” and “ascertaining information about precoding functionality used by the UE”, it is included also the possibility of a network entity which only receives such information and signals indirectly via one or more other nodes. For example, a network entity may be in communication with a gNB, and the gNB may receive SRSs from the UE as well as e.g. instructing the UE to use a certain precoding functionality and / or be informed by the UE about what precoding functionality that is used. This information may then be relayed to the network entity, which may then use this information to e.g. run one or more (AI / ML) models as described herein. In other examples, the responsibility of e.g. receiving SRSs, instructing the UE and / or receive information from the UE, and use the received SRS and ascertained information may be divided among several entities. For example, one entity may receive the SRSs. Another entity may instruct the UE and / or receive the information from the UE, and yet another entity may do the actual using of the information, e.g. as part of processing and / or storing the received SRSs. Thus, although sometimes referring herein to a single “network entity”, it is envisaged that there may be more than one entity responsible for performing e.g. a method as disclosed herein.

[0121] As also envisaged herein, it is noted that a network entity may not necessarily process the received SRSs (or uplink reference signals) directly in connection with receiving the signals, but instead e.g. store these signals (along with the ascertained information about the precoding functionality used to transmit these signals) for later use. For example, data may be stored in order to create training data for one or more AI / ML models, and similar, and such training may of course benefit from having access to both the stored signals as well as to the information about the (at least part of the) precoding functionality used to transmit the signals.

[0122] Various example embodiments of network entities, UEs, computer programs / computer program products as envisaged herein will now be described in more detail with reference also to Figures 5A, 5B, 6A, 6B and 7.

[0123] Figure 5A schematically illustrates, in terms of a number of functional units, the components of an example network entity 500 according to the present disclosure (such as the gNB 210). The network entity 500 may form part of a communications network, such as a telecommunications network (e.g.230) and be configured to e.g. one or more of the various examples of the method 300 of ascertaining information about a precoding functionality of a UE used to send one or more uplink reference signals. The network entity 500 includes processing circuitry 510. The processing circuitry 510 is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), etc., capable of executing software instructions stored in a computer program product 710a (see Figure 7 and the description thereof), e.g. in form of a storage medium 520 that may also form part of the training entity 500. The processing circuitry 510 may further be provided as at least one application specific integrated circuit (ASIC), or field-programmable gate array (FPGA).

[0124] Particularly, the processing circuitry 510 is configured to cause the network entity 500 to perform a set of operations, or steps, as disclosed above e.g. when describing the method 300 illustrated in Figure 3 (and any of Figures 2A, 2B, 2C and 2D). For example, the storage medium 520 may store a set of operations, and the processing circuitry 510 may be configured to retrieve the set of operations from the storage medium 520 to cause the network entity 500 to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus, the processing circuitry 510 is thereby arranged to execute examples of amethod associated with ascertaining of information about a UE precoding functionality as disclosed herein e.g. with reference to Figures 2A, 2B, 2C, 2D and 3.

[0125] The storage medium 520 may also include persistent storage, which, for example, can be any single or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory.

[0126] The network entity 500 may further include a communications interface 530 for communications with other entities, functions, nodes, and devices, such as e.g. those of a telecommunications network or any other network associated with the task to be solved, such as the UE (e.g.220). For example, the communications interface 530 may allow the network entity 500 to communicate with e.g. other entities, with one or more Network Functions (NFs) or nodes of a telecommunications network, or e.g. with one or more internal operational modules within a same node, etc. For example, the communications interface 530 may be configured to receive one or more signals from a UE, either directly or indirectly, including one or more uplink reference signals, as well as to send one or more signals to the UE, either directly or indirectly, including e.g. one or more request messages and capability enquiry messages, and similar. As such, the communication interface 530 may include one or more transmitters and receivers, including analogue and / or digital components.

[0127] The processing circuitry 510 controls the general operation of the network entity 500 e.g. by sending data and control signals to the communications interface 530 and the storage medium 520, by receiving data and reports from the communications interface 530, and by retrieving data and instructions from the storage medium 520. Other components, as well as their related functionality, of the network entity 500 are omitted in order not to obscure the concepts presented herein.

[0128] Figure 5B schematically illustrates, in terms of a number of functional modules 510a, 510b and 510c, the components of a network entity 500 according to one or more examples of the present disclosure. The network entity 500 includes at least a first module 510a configured to perform operation S305 of the method 300 described with reference to Figure 3. The module 510a may be referred to as an “ascertaining module”, “ascertain module” or similar. The network entity 500 also includes a second module 510b configured to perform operation S320. The module510b may be referred to as a “receiving module”, “receive module” or similar. In other examples, both modules 510a and 510b may instead be provided as part of a single module, e.g. as part of a combined ascertain / receive module. The network entity 500 may also include one or more optional functional modules (illustrated by the dashed box 510c), such as for example performing any of the (optional) operations S310, S330, S332, S334, S340, S350 and S352. The network entity 500 may in some examples include one or more functional modules for e.g. implementing an AI / ML model for e.g. predicting / estimating CSI and / or computing downlink precoder parameters, and similar, as described earlier herein, and / or one or more modules configured to e.g. determine what particular (AI / ML) model to use based on the ascertained knowledge / information about the precoding functionality of the UEs.

[0129] In general terms, each functional module 510a-c may be implemented in hardware or in software. Preferably, one or more or all functional modules 510a-c may be implemented by the processing circuitry 510, possibly in cooperation with the communications interface 530 and / or the storage medium 520. The processing circuitry 510 may thus be arranged to from the storage medium 520 fetch instructions as provided by a functional module 510a-c, and to execute these instructions and thereby perform any operations of any example method 300 performed by / in the network entity 500 as disclosed herein.

[0130] Figure 6A schematically illustrates, in terms of a number of functional units, the components of one or more examples of User Equipment (UE) 600 (entities) according to the present disclosure. The UE 600 is configured to assist a network entity (such as 500) to ascertain information about (at least part of) a precoding functionality of the UE used to send one or more uplink reference signals (to the network entity). The UE 600 includes processing circuitry 610. The processing circuitry 610 is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), etc., capable of executing software instructions stored in a computer program product 710b (see Figure 7 and the description thereof), e.g. in form of a storage medium 620 that may also form part of the UE 600. The processing circuitry 610 may further be provided as at least one application specific integrated circuit (ASIC), or field-programmable gate array (FPGA).

[0131] Particularly, the processing circuitry 610 is configured to cause the UE 600 to perform a set of operations, or steps, needed to assist the network, e.g. by performing the method 400 as described with reference to Figure 4. For example, the storage medium 620 may store a set of operations, and the processing circuitry 610 may be configured to retrieve the set of operations from the storage medium 620 to cause the UE 600 to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus, the processing circuitry 610 is thereby arranged to execute examples of the method 400 as disclosed herein, e.g. with reference to any one of Figures 2A, 2B, 2C, 2D and 4.

[0132] The storage medium 620 may also include persistent storage, which, for example, can be any single or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory.

[0133] The UE 600 may further include a communications interface 630 for communications with other entities, functions, nodes, and devices, such as e.g. those of a telecommunications network or any other network associated with the task to be solved. For example, the communications interface 530 may allow the UE 600 to communicate with e.g. a network entity (such as the network entity 500) to assist the latter in ascertaining information about the precoding functionality, and e.g. with one or more Network Functions (NFs) or other nodes of a telecommunications network, or e.g. with one or more operational units / modules within a same NF or node. As such, the communication interface 630 may include one or more transmitters and receivers, including analogue and / or digital components. For example, the communications interface 630 may be used to receive one or more request messages and capability enquiry messages from the network entity, and to send one or more information messages, capability information messages and uplink reference signals to the network entity, either directly or indirectly.

[0134] The processing circuitry 610 controls the general operation of the UE 600 e.g. by sending data and control signals to the communications interface 630 and the storage medium 620, by receiving data and reports from the communications interface 630, and by retrieving data and instructions from the storage medium 620. Other components, as well as their related functionality, of the UE 600 are omitted in order not to obscure the concepts presented herein.

[0135] Figure 6B schematically illustrates, in terms of a number of functional modules 610a-c, the components of a UE 600 according to examples of the present disclosure. The UE 600 includes at least first module 610a configured to perform operation S405 of the method 400 described with reference to Figure 4. The module 610a may be referred to as an “assisting module”, “assist module” or similar. The UE 600 also includes a second module 610b configured to perform operation S420, i.e. to send one or more uplink reference signals. The module 610b may be referred to as a “sending module”, “send module” or similar. In some examples, both of the modules 610a and 610b may of course be implemented as a single module.

[0136] The UE 600 may optionally also include one or more additional modules (illustrated by the dashed box 610c), that may be configured to perform any of the operations S410, S412, S430, S432, S440 and S442.

[0137] In general terms, each functional module 610a-c may be implemented in hardware or in software. Preferably, one or more of the functional modules 610a-c may be implemented by the processing circuitry 610, possibly in cooperation with the communications interface 630 and / or the storage medium 620. The processing circuitry 610 may thus be arranged to from the storage medium 620 fetch instructions as provided by a functional module 610a, 610b and / or 610c (if included), and to execute these instructions and thereby perform the one or more examples of the method 400 as disclosed herein.

[0138] Figure 7 schematically illustrates a computer program product 710a, 710b including computer readable means 730. On the computer readable means 730, a computer program 720a can be stored, which computer program 720a can cause the processing circuitry 510 and thereto operatively coupled entities and devices, such as the communication interface 530 and the storage medium 520, of the network entity 500 to execute one or more of the examples of a method 300 as described with reference to Figures 2A-2D and 3. The computer program 720a and / or computer program product 710a may thus provide means for performing any operations of any method 300 performed by the network entity 500 as disclosed herein.

[0139] On the computer readable means 730, a computer program 720b can also be stored, either in addition to or instead of the computer program 720a, which computer program 720b can cause the processing circuitry 610 and thereto operatively coupled entities and devices, such as the communication interface 630and the storage medium 620, of the UE 600 to assist the network entity 500 in accordance with e.g. any example of the method 400 as described herein with reference to Figures 2A-2D and 4.

[0140] Figure 7 also serves to illustrate an example of the computer readable means 730 in which it stores e.g. training data for, or a model trained based on, the received uplink reference signals and ascertained information about the precoding functionality of the UE. It is envisaged that the computer readable means 730 may include only such data, or such data in combination with one or more of the computer programs 720a, 720b described above, or in combination with any other data.

[0141] In the example of Figure 7, the computer program product 710a, 710b and computer readable means 730 are illustrated as an optical disc, such as a CD (compact disc) or a DVD (digital versatile disc) or a Blu-Ray disc. The computer program product 710a, 710b and computer readable means 730 could also be embodied as a memory, such as a random-access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), or an electrically erasable programmable read-only memory (EEPROM) and more particularly as a non-volatile storage medium of a device in an external memory such as a USB (Universal Serial Bus) memory or a Flash memory, such as a compact Flash memory. Thus, while the computer program 720a, 720b and data are here schematically shown as a track on the depicted optical disk, the computer program 720a, 720b and / or data may be stored in any way which is suitable for the computer program product 710a, 710b and computer readable means 730.

[0142] In summary of all of the above, the present disclosure improves upon current technology in that it enables a network entity (such as a gNB or other base station) to ascertain information about at least part of a precoding functionality used by a UE when sending uplink reference signals to the network entity, by the introduction of additional signaling that enables the network entity to either directly control the behavior of the precoding functionality of the UE, or at least be informed by the UE about such behavior. This allows the network entity to e.g. better utilize (and also train) for example AI / ML-models to perform prediction, estimation and / or computation of one or more quantities based on the received uplink reference signals, as the issue of the precoding functionality changing in an unknown way is at least partly eliminated.

[0143] Although features and elements may be described above in particular combinations, each feature or element may be used alone without the other features and elements or in various combinations with or without other features and elements. Additionally, variations to the disclosed embodiments may be understood and effected by the skilled person in practicing the claimed invention as defined by the appended patent claims, from a study of the drawings, the disclosure, and the appended claims themselves. In the claims, the words “comprising” and “including” does not exclude other elements, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be used to advantage.

Claims

CLAIMS 1. A computer-implemented method (300) for at least partial ascertaining of a User Equipment, UE, precoding functionality during uplink reference signaling, the method being performed by at least one network entity (210) of a telecommunications network (230), the method comprising: - ascertaining (S305) information about at least part of a precoding functionality (^^^^(^^^^)) used by a UE (220) to send one or more uplink reference signals (250), said precoding functionality defining one or more mappings between uplink reference signals and one or more antenna ports of the UE, and - receiving (S320) the one or more uplink reference signals (250) from the UE.

2. The method according to claim 1, wherein the one or more uplink reference signals are sounding reference signals, SRSs.

3. The method according to claim 1 or 2, wherein said ascertaining comprises sending (S310), before said receiving, at least one request message (240) to the UE indicative of the at least part of the precoding functionality to be used by the UE when sending the one or more reference signals.

4. The method according to claim 3, wherein the at least one request message comprises a request for the at least part of the precoding functionality to be fixed until indicated otherwise or during one or more periods of time.

5. The method according to claim 3 or 4, wherein the at least one request message explicitly indicates the at least part of the precoding functionality to be used by the UE when sending the one or more uplink reference signals.

6. The method according to any one of claims 3 to 5, wherein the at least part of the precoding functionality to be used by the UE when sending the one or more uplink reference signals is indicated in the at least one request message as an index of a precoding codebook known to both the UE and the network entity.

7. The method according to any one of claims 3 to 6, wherein the at least one request message comprises a request for the at least part of the precoding functionality to be fixed during sending of a burst of a predefined number of the uplink reference signals.

8. The method according to any one claims 3 to 7, wherein the at least one request message comprises a request for the UE not to change an uplink reference signal transmission power until indicated otherwise or during one or more periods of time.

9. The method according to any one of claims 3 to 8, wherein the at least one request message comprises a request for the UE to transmit at a maximum power or with an otherwise specified power until indicated otherwise or during one or more periods of time.

10. The method according to any one of claims 3 to 9, wherein the at least one request message comprises a request for the UE to indicate to the network entity whenever the at least part of the precoding functionality changes, and / or whenever a difference between a previously used precoding functionality and the precoding functionality used to send the one or more uplink reference signals exceeds a threshold value.

11. The method according to any one of claims 3 to 10, wherein the at least one request message comprises a request for the UE to indicate to the network entity whenever the at least part of the precoding functionality has changed since receiving a previous request message from the network entity and / or during one or more previous slots or periods of time.

12. The method according to any one of claims 3 to 11, wherein the at least one request message comprises precoding weights of the precoding functionality to be used by the UE when sending the one or more uplink reference signals.

13. The method according to any one of the preceding claims, wherein said ascertaining comprises receiving (S340) at least one information message (252) fromthe UE indicative of the at least part of the precoding functionality used by the UE when sending the one or more uplink reference signals.

14. The method according to any one of the preceding claims, further comprising using (S330) the ascertained information about the at least part of the precoding functionality as part of a processing (S332) and / or storing (S334) of the receive one or more uplink reference signals.

15. The method according to claim 14, wherein said processing comprises estimating and / or predicting channel state information, CSI, and / or computing one or more downlink precoders based on the received one or more uplink reference signals.

16. The method according to claim 15, further comprising using a Machine Learning model (110) trained to perform said estimating, predicting and / or computing based on received uplink reference signals.

17. The method according to claim 16, further comprising selecting the Machine Learning model based on whether the ascertained information about the at least part of the precoding functionality indicates that the UE uses time bundling for sending the one or more uplink reference signals.

18. The method according to any one claims 14 to 17, wherein said storing comprises storing the received one or more uplink reference signals for use as training data for a Machine Learning algorithm.

19. The method according to any one of the preceding claims, further comprising sending (S350) a capability enquiry message (242) to the UE to confirm that i) the UE is capable of adapting the at least part of its precoding functionality in accordance with a request message sent to the UE from the network entity, and / or ii) that the UE is capable of providing at least one information message indicative of the at least part of its precoding functionality.

20. The method according to claim 19, wherein the capability enquiry message is or forms part of a UECapabilityEnquiry message.

21. The method according to any one of the preceding claims, wherein the network entity is one of a generic network node, a base station such as a gNB, a relay node, a core network node or any other device capable of directly or indirectly communicating with the UE.

22. A computer-implemented method (400) for assisting at least one network entity (210) of a telecommunications network (230) in at least partial ascertaining of a User Equipment, UE, (220) precoding functionality during uplink reference signaling, the method being performed by the UE, the method comprising: - assisting (S405) at least one network entity (210) in ascertaining at least part of a precoding functionality (^^^^(^^^^)) of the UE used to send one or more uplink reference signals, wherein said precoding functionality defines one or more mappings between uplink reference signals and one or more antenna ports of the UE, and - sending (S420) one or more uplink reference signals (250) to the at least one network entity using the precoding functionality.

23. The method according to claim 22, wherein the one or more uplink reference signals are Sounding Reference Signals, SRSs.

24. The method according to claim 22 or 23, comprising keeping the at least part of the precoding functionality fixed during sending of the one or more uplink reference signals.

25. The method according to any one of claims 22 to 24, comprising keeping the at least part of the precoding functionality fixed until indicated otherwise or during one or more periods of time.

26. The method according to any one of claims 22 to 25, comprising keeping the at least part of the precoding functionality fixed during sending of a burst of a predefined number of uplink reference signals.

27. The method according to any one of claims 22 to 26, comprising not changing an uplink reference signal transmission power until indicated otherwise or during one or more periods of time.

28. The method according to any one of clams 22 to 27, comprising transmitting at a maximum power or with an otherwise specified power until indicated otherwise or during one or more periods of time.

29. The method according to any one of claims 22 to 28, comprising using time bundling for sending the one or more uplink reference signals.

30. The method according to any one of claims 22 to 29, wherein said assisting comprises sending (S430) at least one information message (252) to the at least one network entity indicative of the at least part of the precoding functionality used by the UE when sending the one or more uplink reference signals.

31. The method according to claim 30, wherein the at least one information message comprises an explicit indication of the at least part of the precoding functionality used by the UE when sending the one or more uplink reference signals.

32. The method according to claim 30 or 31, wherein the at least part of the precoding functionality is indicated in the at least one information message as an index of a precoding codebook known to both the UE and the network entity.

33. The method according to any one of claims 30 to 32, comprising sending the at least one information message whenever the at least part of the precoding functionality changes, and / or whenever a difference between a previously used precoding functionality and the precoding functionality used to send the one or more uplink reference signals exceeds a threshold value.

34. The method according to any one of claims 30 to 33, comprising sending the at least one information message whenever the at least part of the precoding functionality changes since receiving a previous request message from the network entity and / or during one or more previous slots or periods of time.

35. The method according to any one of claims 30 to 34, wherein the at least one information message comprises precoding weights of the precoding functionality of the UE.

36. The method according to any one of claims 30 to 35, wherein the at least one information message comprises a maximum phase error between different uplink reference signal transmissions within a period of time during which it is indicated by the UE that the at least part of the precoding functionality is fixed.

37. The method according to any one of claims 22 to 36, further comprising sending (S442) a capability information message (254) to the network entity informing the network entity that i) the UE is capable of adapting the at least part of its precoding functionality in accordance with a request message sent from the network entity to the UE, and / or ii) that the UE is capable of providing at least one information message indicative of the at least part of the precoding functionality to the network entity.

38. The method according to claim 37, wherein the capability information message is or form parts of a UECapabilityInformation message.

39. The method according to claim 37 or 38, further comprising receiving (S440) a capability enquiry message (242) from the network entity, and sending the capability information message in response to receiving said capability enquiry message.

40. The method according to any one of claims 22 to 39, wherein said assisting comprises receiving (S410) at least one request message (240) from the at least one network entity indicative of the at least part of the precoding functionality to be used by the UE when sending the one or more uplink reference signals, and adapting (S412) the precoding functionality in accordance with the received at least one request message before sending the one or more uplink reference signals.

41. A network entity (210, 500) for a telecommunications network (230), comprising processing circuitry (510) and a memory (520) storing instructions,wherein the instructions are such that they, when executed by the processing circuitry, cause the network entity to: - ascertain (S305) information about at least part of a precoding functionality (^^^^(^^^^)) used by a User Equipment, UE, (220, 600) to send one or more uplink reference signals, wherein said precoding functionality defines one or more mappings between uplink reference signals and one or more antenna ports of the UE, and - receive (S320) one or more uplink reference signals (250) from the UE.

42. The network entity of claim 41, wherein the instructions are further such that they, when executed by the processing circuitry, cause the network entity to perform the method (400) of any one of claims 2 to 21.

43. A User Equipment, UE, (220, 600) for a telecommunications network (230), comprising processing circuitry (610) and a memory (620) storing instructions, wherein the instructions are such that they, when executed by the processing circuitry, cause the UE to: - assist (S405) at least one network entity (210, 500) in ascertaining at least part of a precoding functionality (^^^^(^^^^)) of the UE used to send one or more uplink reference signals, wherein said precoding functionality defines one or more mappings between uplink reference signals and one or more antenna ports of the UE - send (S420) one or more uplink reference signals (250) to the at least one network entity using the precoding functionality.

44. The UE of claim 43, wherein the instructions are further such that they, when executed by the processing circuitry, cause the UE to perform the method (400) of any one of claims 23 to 40.

45. A telecommunications system (230), comprising: - the network entity (210, 500) according to claim 41 or 42, and - the User Equipment, UE, (220, 600) according to claim 43 or 44.

46. A computer program (720a) for a network entity for a telecommunications network (230), the computer program comprising computer code which, when runon processing circuitry (510) of a network entity (210, 500), causes the network entity to: - ascertain (S305) information about at least part of a precoding functionality (^^^^(^^^^)) used by a UE (220, 600) to send one or more uplink reference signals, wherein said precoding functionality defines one or more mappings between uplink reference signals and one or more antenna ports of the UE, and - receive (S320) one or more uplink reference signals (250) from the UE.

47. A computer program product (710a) comprising a computer program (720a) according to claim 46, and a computer-readable storage medium (730) on which the computer program is stored.

48. A computer program (710b) for a User Equipment, UE, for a telecommunications network (230), the computer program comprising computer code which, when run on processing circuitry (610) of a User Equipment, UE, (220, 600), causes the UE to: - assist at least one network entity (210, 500) in ascertaining at least part of a precoding functionality (^^^^(^^^^)) of the UE used to send one or more uplink reference signals, wherein said precoding functionality defines one or more mappings between uplink reference signals and one or more antenna ports of the UE, and - send (S420) one or more uplink reference signals (250) to the at least one network entity using the precoding functionality.

49. A computer program product (710b) comprising a computer program (720b) according to claim 48, and a computer-readable storage medium (730) on which the computer program is stored.

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