Methods and devices for handling channel conditions in a wireless system

Abstract

A method carried out in a wireless network comprising at least one Transmit / Receive Point, TRP, wherein said TRP comprises an antenna array including multiple antennas, said method comprising: transmitting (707), to a first User Equipment, UE, an amplitude adjustment configuration, wherein said amplitude adjustment configuration is indicative of a target amplitude level of receiving a downlink channel at said UE from said TRP.

Description

[0001] METHODS AND DEVICES FOR HANDLING CHANNEL CONDITIONS IN A WIRELESS SYSTEM

[0002] Technical field

[0003] This disclosure relates to methods and devices in a wireless communication system, in which wireless devices may communicate with a wireless network.

[0004] Specifically, solutions are provided for handling varying channel conditions between the network and the wireless devices.

[0005] Background

[0006] In radio communication systems, such as various generations provided through the 3rd Generation Partnership Project (3GPP), various specifications have been provided for setting up common rules for setting up and operating both a wireless radio interface between a wireless device and a network, and various levels of operation of the network. In 3GPP documentation, a wireless device is commonly referred to as User Equipment (UE), a term that will be used throughout this disclosure. Such UEs are connectable to a core network by means of a Radio Access Network (RAN), which includes one or more network nodes, operative to provide radio access to UEs within a cell. Such network nodes may also be referred to as an access node or a base station, and various terms are used in 3GPP for different types of systems or specifications, such as gNB in New Radio (NR), developed to support 5G RAN. Each access node of the wireless network may comprise at least one Transmit / Receive Point (TRP), at which an antenna system of the access node is arranged for radio communication with UEs.

[0007] A well-established technology used in wireless communication is MIMO, Multiple-Input Multiple-Output, which uses an antenna system with multiple antennas at both the transmitter and receiver of each TRP to improve communication performance. This may enhance data rates, signal quality, and network efficiency. MIMO may be used to obtain increased data throughput by transmitting multiple data streams simultaneously using spatial diversity, also referred to as beamforming.

[0008] A further development of the MIMO concept is so called DMIMO, Distributed Multiple-Input Multiple-Output, wherein multiple spatially separated antennas, orTRPs, are used to transmit and receive signals, to further enhance network performance. Other terms used for labelling this general wireless communication principle are cell-free MIMO (CF-MIMO), (CF-MIMO), CF massive MIMO, and Coordinated MultiPoint systems. For the sake of simplicity, the term DMIMO will be used herein to describe this general concept. Unlike, or in extension to, conventional MIMO, where antennas are co-located in an antenna system at a single TRP, DMIMO places antennas or antenna systems across different locations. Such a system configuration may, inter alia, help reducing dead zones and improve connectivity in challenging environments, and may support more UEs by reducing interference and enabling better frequency reuse.

[0009] In wireless systems where a TRP shall serve a plurality of different UEs, which may typically be located at different places, a signal processing technique known as precoding is used to improve data transmission by shaping signals before they are sent from the transmitter to the receiver. Precoding directs signals toward specific UEs using beamforming. In a multi-TRP configuration, such as DMIMO, precoding suppresses inter-TRP interference and may be employed to ensure or promote coherent signal transmission to a target UE.

[0010] In DMIMO systems, the network performs precoding to separate multiple UEs. The network has two options to handle different and varying channel conditions between a TRP and a UE. Either, the network allows the channel to vary over time, implying that the power consumption of the network is stable and that the UE will adapt to varying channel conditions by gain control of received signals. Alternatively, the precoding is configured such that the channels perceived by the UE are constant over time. In such a concept, power consumption in the TRP varies considerably over time. Appropriate handling of varying channel conditions is thus a challenging topic.

[0011] Summary

[0012] In view of these challenges, various solutions are provided herein and set out in the independent claims. Further aspects and examples of the proposed solution are set out in the dependent claims, in the following description, and in the drawings.According to one aspect, the proposed solution relates to a method carried out in a wireless network comprising at least one Transmit / Receive Point, TRP, wherein said TRP comprises an antenna array including multiple antennas, said method comprising:

[0013] transmitting, to a first User Equipment, UE, an amplitude adjustment configuration,

[0014] wherein said amplitude adjustment configuration is indicative of a target amplitude level of receiving a downlink channel at said UE from said TRP.

[0015] According to one aspect, the proposed solution relates to a network node of a wireless network, wherein said network node is configured to control at least one Transmit / Receive Point, TRP, which comprises an antenna array including multiple antennas, wherein the network node comprises:

[0016] logic circuitry configured to control the at least one TRP to transmit, to a first User Equipment, UE, an amplitude adjustment configuration, wherein said amplitude adjustment configuration is indicative of a target amplitude level of receiving a downlink channel at said UE from said TRP.

[0017] Brief description of the drawings

[0018] Fig. 1 schematically illustrates a general setup of communication between a TRP of a wireless network and a UE in a wireless communication system.

[0019] Fig. 2 schematically illustrates a UE configured to operate according to various embodiments outlined herein.

[0020] Fig. 3 schematically illustrates a network node which may comprise or control a TRP of the wireless network, according to various embodiments outlined herein.

[0021] Fig. 4 schematically illustrates a setup wherein a UE is configured to communicate with multiple TRPs, which may be configured according to DMIMO.

[0022] Fig. 5A shows diagrams schematically illustrating two different control principles for handling varying channel conditions.

[0023] Fig. 5B shows a diagram visualizing abrupt change of connectivity between TRP, according to a scenario associated with various examples of the proposed solution.

[0024] Fig. 6 shows a diagram visualizing variation of various control parameters for handling a downlink channel on account of UEs being added or dropped.Fig. 7A shows a flow chart of a method carried out in the wireless network according to various examples of the proposed solution.

[0025] Fig. 7B shows a flow chart of a method carried out in the wireless network according to various examples of the proposed solution, which may be implemented together with the method of Fig. 7 A.

[0026] Fig. 8 schematically illustrates a diagram with different examples of applied control mechanism.

[0027] Detailed description

[0028] The invention will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0029] It will be understood that, when an element is referred to as being “connected” to another element, it can be directly connected to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” to another element, there are no intervening elements present. Like numbers refer to like elements throughout. It will furthermore be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present invention. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0030] Well-known functions or constructions may not be described in detail for brevity and / or clarity. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and therelevant art and will not be interpreted in an idealized or overly formal sense expressly so defined herein.

[0031] Embodiments of the invention are described herein with reference to schematic illustrations of idealized embodiments of the invention. As such, variations from the shapes and relative sizes of the illustrations as a result, for example, of manufacturing techniques and / or tolerances, are to be expected. Thus, embodiments of the invention should not be construed as limited to the particular shapes and relative sizes of regions illustrated herein but are to include deviations in shapes and / or relative sizes that result, for example, from different operational constraints and / or from manufacturing constraints. Thus, the elements illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the invention.

[0032] Before going into further detail, a general presentation is provided with reference to the drawings of the communication entities of the wireless system in which the proposed solution may be set out.

[0033] Fig. 1 schematically illustrates a wireless communication system including a wireless network 100, and a UE 1 configured to wirelessly receive radio signals from the wireless network 100. The wireless network may be a radio communication network operating under general and specific regulations and limits published by the 3GPP, such as a New Radio (NR) network. The wireless network 100 may include a core network 110, which is connected to other networks 130, such as the Internet. The wireless network 100 further includes an access network, such as a RAN, which may comprise a plurality of access nodes, of which access node 120 is shown in Fig. 1. An access node is an entity executing the wireless connection with wireless UEs 10. As such, the access node 120 comprises or is connected to a Transmit / Receive Point (TRP) including an antenna arrangement, or antenna system, for transmitting and receiving radio signals. The access node 120 may also be referred to as a base station and may be a gNB.

[0034] Fig. 2 schematically illustrates an embodiment of the UE 1 for use in a wireless network 100 as presented herein, and for carrying out the method steps as outlined. The UE 1 may comprise a radio transceiver 213 for communicating with other entities of the radio communication network 100, such as the access node 120. The transceiver 213 may thus include a receiver and a transmitter for communicating by radio over an air interface.The UE 1 may further comprise an antenna system 214, which may include one or more antennas, antenna ports or antenna arrays. The antenna system 214 is connected to the transceiver for wireless communication of radio signals. The antenna system 214 may be configured for beamforming. The antenna system 214 may thus be configured to employ an anisotropic sensitivity profile of the antenna system to communicate radio signals in a particular direction, so called beam steering.

[0035] The UE 1 further comprises logic circuitry 210 configured to control communication of data and control signals, via the radio transceiver 213, on a physical channel 140 with the wireless communication network 100. The logic circuitry 210 may further be configured to control the antenna system 214 for beamforming and beam steering.

[0036] The logic circuitry 210 may include a processing device 211, including one or multiple processors, microprocessors, data processors, co-processors, and / or some other type of component that interprets and / or executes instructions and / or data. The processing device 211 may be implemented as hardware (e.g., a microprocessor, etc.) or a combination of hardware and software (e.g., a system-on-chip (SoC), an applicationspecific integrated circuit (ASIC), etc.). The processing device 211 may be configured to perform one or multiple operations based on an operating system and / or various applications or programs.

[0037] The logic circuitry 210 may further include memory storage 212, which may include one or multiple memories and / or one or multiple other types of storage mediums. For example, the memory storage 212 may include a random access memory (RAM), a dynamic random access memory (DRAM), a cache, a read only memory (ROM), a programmable read only memory (PROM), flash memory, and / or some other type of memory. The memory storage 212 may include a hard disk (e.g., a magnetic disk, an optical disk, a magneto-optic disk, a solid state disk, etc.). The memory storage 212 is configured for holding computer program code, which may be executed by the processing device 211, wherein the logic circuitry 210 is configured to control the UE 1 to carry out any of the method steps as provided herein. Software defined by said computer program code may include an application or a program that provides a function and / or a process. The software may include device firmware, an operating system (OS), or a variety of applications that may execute in the logic circuitry 210.Obviously, the UE 1 may include other features and elements than those shown in the drawing or described herein, such as a power supply, a casing, a user interface, sensors, etc., but these are left out for the sake of simplicity.

[0038] Fig. 3 schematically illustrates a network node 300 of the network 100 as presented herein, and for carrying out the method steps as outlined.

[0039] In some examples, the network node 300 is an access node 120 of the wireless network 100.

[0040] In some examples, the network node 300 is connectable to control an access node 120.

[0041] In some examples, the network node 300 comprises or is connectable to a TRP. In some examples, a plurality of access nodes 120 may be configured to carry out synchronized transmission to a common, i.e., the same, UE 1, as will be exemplified with reference to Fig. 4. In such context, uplink transmission from said UE 1 may be carried out to one specific access node 120 among said plurality of access nodes, for connection with network 100.

[0042] In some examples, various access points may thus be referred to as transmission points 120, which are at least configured for radio transmission and optionally for uplink reception.

[0043] In some examples, the network node 300 comprises or is connected to control a transmission point, such as a TRP. In various embodiments, the network node 300 comprises or is connectable to control a base station for operation in the radio communication network 100, to serve one or more UEs, such as the UE 1.

[0044] Description of the network node 300 is provided below for an embodiment where the network node 300 comprises or implements an access node 120, which may comprise or be configured to control a TRP.

[0045] The network node 300 may comprise a wireless transceiver 313, such as a radio transceiver for communicating with other entities of the radio communication network 100, such as the terminal 10. The transceiver 313 may thus include a radio receiver and a radio transmitter for communicating through at least an air interface.

[0046] The network node 300 may further comprise, or be connected to, an antenna system 314, which may include a plurality of antennas, such as an antenna array. The antenna system 214 may be configured to control the radio transceiver to employ an anisotropic sensitivity profile to transmit radio signals in a particular transmit direction.In some examples, the antenna system forms part of a transmission point, or TRP, included in or connected to the network node 300.

[0047] The network node 300 further comprises logic circuitry 310 configured to control the network node 300 to communicate with the UE 1 via the radio transceiver 313 on a physical channel 140.

[0048] The logic circuitry 310 may include a processing device 311, including one or multiple processors, microprocessors, data processors, co-processors, and / or some other type of component that interprets and / or executes instructions and / or data. Processing device 311 may be implemented as hardware (e.g., a microprocessor, etc.) or a combination of hardware and software (e.g., a system-on-chip (SoC), an applicationspecific integrated circuit (ASIC), etc.). The processing device 311 may be configured to perform one or multiple operations based on an operating system and / or various applications or programs.

[0049] The logic circuitry 310 may further include memory storage 312, which may include one or multiple memories and / or one or multiple other types of storage mediums. For example, memory storage 312 may include a random access memory (RAM), a dynamic random access memory (DRAM), a cache, a read only memory (ROM), a programmable read only memory (PROM), flash memory, and / or some other type of memory. Memory storage 312 may include a hard disk (e.g., a magnetic disk, an optical disk, a magneto-optic disk, a solid state disk, etc.).

[0050] The memory storage 312 is configured for holding computer program code, which may be executed by the processing device 311, wherein the logic 310 is configured to control the network node 300 to carry out any of the method steps as provided herein. Software defined by said computer program code may include an application or a program that provides a function and / or a process. The software may include device firmware, an operating system (OS), or a variety of applications that may execute in the logic 310.

[0051] The network node 300 may further comprise an interface 315, configured for communication with the core network 110. Obviously, the network node 300 may include other features and elements than those shown in the drawing or described herein, such as a power supply and a casing etc.

[0052] In some examples, the solutions proposed herein may be set out in the context of a DMIMO system in which a plurality of UEs is served by a plurality of TRPs in the sametime-frequency resources. Such an example is visualized in Fig. 4. Herein, three TRPs: TRP1, TRP2, TRP3, are shown to serve the same UE 1. In this context, each of said TRPs may be configured in accordance with the access node 120.

[0053] The network 100 is configured to acquire Channel State Information, CSI. This may be obtained according to the established art, which may include both uplink (UL) and downlink (DL) training. Obtained CSI may be used to separate different UEs in the system by means of, e.g., zero-forcing precoding. In order to ease understanding of the proposed solution, the following may be noted.

[0054] Let M denote the total number of TRP antennas in the antenna system 314, and let the number of served UEs by the network 100 at slot time t be Kt. Within a frequency coherence interval, e.g., a PRB, the received signal at a certain time-frequency resource in the DL at the KtUEs may be described as

[0055] yt= Htxt+ nt

[0056] where ytis a KtX 1 vector, Hta KtX M channel matrix, xta M X 1 transmit vector, and nta KtX 1 noise / interference vector. Note that all variables, save for xt, has varying dimension depending on t, which stems from the fact that the number of served UEs, Kt, may not be constant over time. The assumption of the network 100 possessing CSI implies that an approximate version, Ht, of Htis available at the network 100.

[0057] Let stdenote a KtX 1 vector of data symbols (e.g., QAM) to be transmitted to the KtUEs. To separate the UEs, the network 100 applies precoding, i.e., xtis a processed version of st. The precise type of precoding is irrelevant for the purposes of the proposed solutions, but from the network’s 100 perspective, the precoding is such that the received signal ytmay be modelled as

[0058] yt= diag([dt(l) dt(2) ... dtKt)])st+ wt

[0059] where diag(-) is a diagonal matrix whose argument appears along the main diagonal. Further, wtmay encompass both noise and inter-user interference (in case inter-user interference is not fully suppressed by the precoding). Therefore, the entries of wtmay have different variances. Lastly, dt(k) is the amplitude gain of the k:th user at time t.Note that all linear precoders are included in this framework, e.g., zero-forcing, MMSE, and maximum ratio transmission. A remark can be added to the wording “from the network’s 100 perspective” used above: As the CSI Htmay be noisy, i.e., HtA Ht, the received signal may not exactly abide the above equation.

[0060] It can further be noted that for a given t, the amplitudes dt(k) may vary wildly across the variable k. The reason being that the network 100, most commonly, has a power budget / constraint per TRP. Therefore, a UE m being nearby a certain TRP may have a much larger dt(m) than that of another UE m' being further away. This is not a consequence of fairness, but just that raising dt(m') further would violate power constraints. In some cases, a low dt(fc) is, however, a consequence of fairness. UEs that experience very similar channels (in an inner product sense), may require an unreasonable amount of the total power budget to obtain large values of dt(fc).

[0061] To wit. The network will serve the KtUEs with different amplitude gains due to a variety of reasons.

[0062] Over time, the channel matrix Htmay change. This may happen if the number of served UEs, Kt, changes, or naturally due to movements of the UEs and / or scattering objects. As a consequence, the amplitudes dt(fc) may change over time. This happens for example if a strict power budget is adopted, e.g., || xt||2= P; if the channel becomes “better”, then with the same transmit power P stronger dt(k) channels can be accommodated, while the reverse is true if the channel becomes “worse”. Another case common in DMIMO is that each TRP has its own budget. In that case we may partition xtas

[0063]

[0064] is the transmit vector from the q:th TRP, and constrain, e.g.,

[0065]

[0066] ||2= P / Q. However, to relax the burden of channel estimation / tracking at the UE side, the network may choose to temporarily increase / decrease the transmit powers. Inasmuch as regulatory conditions are met, the precoding may be performed in such a way that dt(fc) = d(k), Vt; that is, the channel per UE is constant over time.

[0067] Reference signals which specifically are transmitted over the channel, such as demodulation reference signals (DMRS) included in DL transmission, can be used to, e.g., estimate the actual channel as the channel is not constant, since the CSI Htis only approximative. Another use for the DMRS is to estimate noise / interference power.Fig. 5A illustrates two substantially opposite approaches. On, the left-hand side the y axis indicates the amplitude level, here referred to as gain, of the downlink channel as it is received at the UE. On the right-hand side the y axis indicates transmit power of the TRP. In the upper plot, let’s call it configuration type a), the network 100 uses the same transmit power over time. As a consequence, the amplitude level per UE (here shown for UE 1), as it is received at the UE, varies over time and needs to be tracked by the UE. In the lower plot, configuration type b), the network 100 is instead configured to equalize the perceived amplitude level, such that it is promoted to be constant across time. This implies that the transmit power typically changes over time. Both transmission formats may be adopted by the network 100, but equalizing the amplitude levels appears to be the more preferred in contemporary literature as it produces more stable data rates.

[0068] Fig. 5B, on the other hand, illustrates an aspect of the challenges associated with handling of varying channel conditions, using the same y axes as Fig. 5A. The dash-dotted curve shows the amplitude level (gain) dt(l) as received at the UE for a network that is configured to maintain, or promote, a constant power constraint over time, i.e., a configuration corresponding to type a) in the upper plot of Fig. 5A. The dashed curve, on the other hand, shows the required transmit power to support a constant amplitude level at the UE, i.e., a configuration corresponding to type b) shown in the lower plot of Fig. 5A, where the full line curve indicates the associated amplitude level as received at the UE. However, after time t = t1?the channel deteriorates which manifests itself through a lowered gain, or amplitude level, for constant power configuration according to type a), or increased power for constant amplitude gain according to type b). At time t = t3, a network configured according to type b) may determine that it may no longer keep increasing the transmit power. The network therefore adapts the amplitude level (different UEs may have different adaptations, and some may not be adapted at all). For the example given, the amplitude level dt(l) which the network will attempt to maintain constant over time, is decreased in order for the network to be able to transmit with its desired power (e.g., to not exceed a limit value Pcut). This adjustment of the configured amplitude level (gain) may cause deteriorated and failed connectivity on the downlink channel.

[0069] Fig. 6 schematically illustrates a diagram showing variations caused by the number of UEs, Kt, to serve being changed, wherein the effect is further pronounced.Corresponding to Fig. 5B, the full line curve indicates changes in configured amplitude level to be received at the UE, based on controlling transmit power at the TRP, whereas the dash-dotted curve indicates required gain control in the UE, based on DMRS measurement, if constant transmit power at the TRP is used. When more UEs are added from one slot to another, a larger number of UEs must share the same power resources. This may imply that an already existing UE gets its amplitude gain heavily reduced (and vice versa when UEs are dropped).

[0070] Based on the foregoing, the proposed solution is associated with a method carried out in a wireless network 100 comprising at least one TRP, wherein said TRP comprises an antenna array 314.

[0071] According to one aspect, the proposed solution provides a method carried out in a wireless network comprising at least one TRP, wherein said TRP comprises an antenna array including multiple antennas, said method comprising:

[0072] transmitting, to a first UE, an amplitude adjustment configuration,

[0073] wherein said amplitude adjustment configuration is indicative of a target amplitude level of receiving a downlink channel at said UE from said TRP.

[0074] According to another aspect, the proposed solution provides a network node 300 of a wireless network 100, wherein said network node is configured to control at least one TRP which comprises an antenna array 314 including multiple antennas, wherein the network node comprises:

[0075] logic circuitry 310 configured to control the at least one TRP to:

[0076] transmit, to a first UE, an amplitude adjustment configuration, wherein said amplitude adjustment configuration is indicative of a target amplitude level of receiving a downlink channel at said UE from said TRP.

[0077] In various embodiments, the logic circuitry 310 is further configured to control the network node in accordance with any of the steps, features and details outlined herein.

[0078] According to some examples, the proposed solution is set out in a wireless system wherein the network 100 is configured to provide synchronized signal transmission from a plurality of TRPs, including said at least one TRP, to the same UE.

[0079] According to some examples, the network 100 is configured to provide said synchronized signal transmission in a common set of time-frequency resources.According to some examples, the network 100 is configured to provide coherent transmission from the plurality of TRPs to said UE.

[0080] According to some examples, the plurality of TRPs may be configured to transmit in a D-MIMO configuration to said UE.

[0081] As an exemplary reference, the plurality of TRPs may comprise TRP1, TRP2, and TRP3 of Fig. 4.

[0082] In some examples, the method is carried out in a network node, such as the access node 120, which comprises or controls at least one TRP.

[0083] In some examples, the proposed solution refers to a downlink channel, which may be a PDSCH or a PDCCH (Physical Downlink Control Channel).

[0084] For ease of understanding, the at least one TRP, which may be implemented or controlled by the network node 300, will be referred to as TRP1, and the UE will be referred to as the UE 1.

[0085] Fig. 7A shows a flowchart of steps that may be carried out in the wireless network, and various aspects related to the proposed solution will be described with reference to said flow chart.

[0086] 701 indicates that the TRP1 is configured to control transmission of a downlink channel to the UE 1 to promote constant reception over time at the UE 1 at a first target amplitude level.

[0087] In some examples, the network 100 is configured to aim at equalizing amplitude levels, or gains, as received by at least the UE 1, and optionally all its served UEs.

[0088] As will be described with reference to Fig. 7B, the configuration of the TRP1 to control transmission of a downlink channel to the UE 1 to promote constant reception over time may include, or be complemented by, an optional configuration of reference signal transmission with dynamically controlled repetition rate from the TRP1, which reference signals are usable for channel estimation by the UE 1.

[0089] In some examples, step 701 may comprise transmitting, from the wireless network, a message or signal for reception in the first UE 1, comprising an indication that the network 100 will make processing to promote a constant amplitude level of the downlink channel at the UE 1.

[0090] 703 indicates that the network 100 may detect a connectivity change.

[0091] According to some examples, the connectivity change is foreseen, by the network 100, to cause an abrupt change of the received amplitude level at the UE 1.According to some examples, the connectivity change may comprise a change in transmit power of said downlink channel from said TRP. By way of example, this may be understood by the description provided with reference to Fig. 5B.

[0092] According to some examples, the connectivity change may comprise added or dropped connection of at least one UE to the TRP. By way of example, this may be understood by the description provided with reference to Fig. 6.

[0093] 705 indicates the optional step of the network 100 determining and amplitude adjustment.

[0094] According to some examples, determining comprises computing said amplitude adjustment based on a previously configured target amplitude level received at the UE 1, such as the first target amplitude value.

[0095] According to some examples, the amplitude adjustment is determined based on the detected connectivity change.

[0096] According to some examples, the amplitude adjustment is determined based on a transmit power change at said TRP 1.

[0097] 707 indicates that the network transmits, to the UE 1, an amplitude adjustment configuration, wherein said amplitude adjustment configuration is indicative of a target amplitude level of receiving a downlink channel at said UE from said TRP.

[0098] According to some examples, the amplitude adjustment configuration is indicative of the target amplitude level which the network 100, going forward, will aim at being received at said UE of said downlink channel.

[0099] According to some examples, the amplitude adjustment configuration is indicative of an adjustment of the target amplitude level.

[0100] According to some examples, the amplitude adjustment configuration is indicative of a stepwise adjustment of the target amplitude level.

[0101] According to some examples, the amplitude adjustment configuration is indicative of a relative adjustment of the target amplitude level.

[0102] According to some examples, the relative adjustment is configured as a dB value, or a ratio based on which the adjusted target amplitude level may be determined by the UE 1 based on previous (first) target amplitude level.

[0103] According to some examples, the relative adjustment is indicative of a magnitude of adjustment of the target amplitude level.According to some examples, the amplitude adjustment configuration comprises an ID of the TRP for which the amplitude adjustment applies.

[0104] According to some examples, the amplitude adjustment configuration comprises a value of said target amplitude level, as adjusted.

[0105] According to some examples, the aforementioned examples may provide that the amplitude adjustment configuration is indicative of an abrupt change of said downlink channel.

[0106] According to some examples, the aforementioned examples may provide that the amplitude adjustment configuration is indicative of a magnitude of the abrupt change of said downlink channel.

[0107] According to some examples, the aforementioned examples may provide that the amplitude adjustment configuration comprises a trigger for the UE to estimate the amplitude adjustment.

[0108] According to some examples, the amplitude adjustment configuration comprises configuration of a downlink reference signal transmitted by the TRP, wherein the reference signal is usable for the UE to estimate the amplitude adjustment.

[0109] According to some examples, the reference signal is dedicated to said UE.

[0110] According to some examples, the reference signal is a DMRS.

[0111] 709 indicates that the TRP 1, subsequently, is configured to control transmission of the downlink channel to promote constant reception over time at said UE at said target amplitude level as adjusted based on the amplitude adjustment configuration.

[0112] According to some examples, the TRP 1 is configured to control transmission by precoding.

[0113] The proposed solution, which may be configured according to any of the aforementioned examples, provides a beneficial addition to control of a wireless system in which the network 100 aims at equalizing amplitude levels, or gains, of the UEs it serves to function in practice. The proposed solution is particularly beneficial for use in a system operating according to DMIMO (or corresponding, as mentioned).

[0114] By way of example, whenever the network determines a connectivity change that may or is deemed to cause an abrupt change in the downlink channel, the network 100 reconfigures target amplitude levels for the UEs.As noted, such an abrupt change may be caused, or triggered, by the transmit power, of the TRP 1 which transmits the downlink channel, exceeding what is willing or allowed to transmit.

[0115] As also noted, such an abrupt change may be caused, or triggered, by the network determining that the target amplitude value may be drastically increased without the TRP 1 risking violating its power constraints.

[0116] The network 100 transmits amplitude adjustment configuration to the UE 1 (and optionally any of the UEs to which the corresponding downlink channel may be affected, wherein (at least) the UE 1 is informed about exact adaptation of the target amplitude level.

[0117] By the transmission of the amplitude adjustment configuration as described, the risk for deterioration or loss of throughput, and data retransmission, on the downlink channel is minimized, as the UE 1 is promptly informed of the reconfiguration of the TRP 1 with regard to the target amplitude level. This may be particularly beneficial upon an abrupt change occurring, or being deemed to occur, on the downlink channel. The transmission of the amplitude adjustment configuration suggested removes or minimizes the need for UEs to monitor reference signals, such as DMRS, to continuously detect whether the network makes changes affecting the downlink channel.

[0118] According to some examples, the proposed solution as described above is employed in a configuration of the network 100 is configured to promote full equalization of the target amplitude level, as received by the UE, wherein the target amplitude level is forced to be constant over time until transmitting an amplitude adjustment configuration, which may cause an abrupt reconfiguration of the target amplitude level.

[0119] Fig. 8 schematically illustrates gain control according to another example. Herein, corresponding to Fig. 5B, the full line curve indicates changes in configured amplitude level to be received at the UE, based on controlling transmit power at the TRP. In such a system, DMRS are not required. The dash-dotted curve indicates required gain control in the UE, based on DMRS measurement, if constant transmit power at the TRP is used.

[0120] The dashed curve indicates a system configuration wherein target amplitude level configuration may be transmitted as previously described., e.g., upon an abrupt change on the downlink channel, which may refer to a change exceeding a certain thresholdvalue in transmit power or in assumed received amplitude at the UE. Moreover, the network 100 may be configured to transmit reference signals, such as DMRS, to further assist the UE in making local gain control to adjust for smaller changes in the received amplitude level.

[0121] Such a configuration of the system allows for considerably lower density of DMRS transmission, i.e., lower repetition rate, than in a system which makes use of constant transmit power from the TRPs.

[0122] Fig. 7B shows a flowchart of steps that may be carried out in the wireless network, and various aspects related to the proposed solution will be described with reference to said flow chart. It shall be noted that the examples described with reference to Fig. 7B may be configured and carried out in combination, and overlapping in time, with the examples described with reference to Fig. 7A. In an alternative scenario, the proposed solution may be configured according to any of the examples described with reference to Fig. 7B alone.

[0123] 711 indicates that the TRP1 is configured to transmit, to the UE 1, configuration of transmission of a reference signal by the TRP for channel estimation by the UE.

[0124] According to some examples, the reference signal is configured for said UE, as a dedicated reference signal.

[0125] According to some examples, the reference signal is a DMRS.

[0126] According to some examples, the configuration is indicative of resources, e.g., in time and / or frequency, of the reference signal.

[0127] According to some examples, the configuration is indicative of a repetition rate of the reference signal.

[0128] According to some examples, the repetition rate is indicative of repetition in the time domain.

[0129] 713 indicates that the TRP transmits the reference signal on the downlink channel, according to the configuration in step 711.

[0130] 715 indicates that the network dynamically controls repetition rate of the reference signal.

[0131] According to some examples, the repetition rate is dynamically controlled based on a level of variance of transmit power.According to some examples, the repetition rate is dynamically controlled based on a level of variance of transmit power to maintain constant amplitude levels to all UEs configured to receive transmission from said TRP.

[0132] According to some examples, the level of variance is an anticipated or assumed level of variance.

[0133] According to some examples, the repetition rate is dynamically increased based on the variance of increasing or exceeding a threshold value.

[0134] According to some examples, the anticipated level of variance is based on a connectivity change between said TRP and at least one UE, such as an actual or relative number of added or dropped UEs served by the TRP1.

[0135] According to some examples, the repetition rate is dynamically controlled dependent on a rate or frequency of transmitting amplitude adjustment configuration.

[0136] 717 indicates that, upon changing repetition rate based on the dynamic controlling 715, the network 100 (e.g., using the TRP which transmits the reference signals), is configured to transmit a message indicative of applied repetition rate to the UE.

[0137] According to some examples, the amplitude adjustment configuration comprises the configuration of transmission of the reference signal and the message indicative of applied repetition rate,

[0138] wherein said amplitude adjustment configuration controls the UE to monitor said reference signals to estimate the target amplitude level of receiving the downlink channel at said UE from said TRP.

[0139] An additional benefit is that from the indication 717 of repetition rate, the UE 1 may extract information how its time-domain filters for channel averaging over time should be configured. In some examples, a practical channel estimator employed in the UE 1 may combine past reference signal observations with a present observation to obtain a more reliable channel estimate. Based on the indication of the repetition rate, the UE may configure weighting for proper combination of repeated reference signal measurements.

[0140] Various details and aspects related to the proposed solution have been outlined in the foregoing. It shall be noted that any of the three embodiments described, and the associated examples, may be used in combination.

[0141] The proposed solution may further be embodied in accordance with any combination of the items set out below and in accordance with the appended claims.Item 1. A method carried out in a wireless network comprising at least one Transmit / Receive Point, TRP, wherein said TRP comprises an antenna array including multiple antennas, said method comprising:

[0142] transmitting (707), to a first User Equipment, UE, an amplitude adjustment configuration,

[0143] wherein said amplitude adjustment configuration is indicative of a target amplitude level of receiving a downlink channel at said UE from said TRP.

[0144] Item 2. The method of item 1, wherein the TRP is configured to control transmission of the downlink channel to promote constant reception over time at said UE at said target amplitude level as adjusted based on the amplitude adjustment configuration.

[0145] Item 3. The method of any item 1 or 2, wherein said amplitude adjustment configuration is indicative of an adjustment of a previously configured target amplitude level.

[0146] Item 4. The method of any preceding item, wherein said amplitude adjustment configuration is indicative of a stepwise adjustment of the target amplitude level. Item 5. The method of any preceding item, wherein said amplitude adjustment configuration is indicative of a relative adjustment of the target amplitude level.

[0147] Item 6. The method of any preceding item, wherein said amplitude adjustment configuration is indicative of a magnitude of adjustment of the target amplitude level.

[0148] Item 7. The method of any of items 3-6, wherein said amplitude adjustment configuration comprises an ID of the TRP for which the amplitude adjustment applies.

[0149] Item 8. The method of any of items 3-7, further comprising:

[0150] computing (705) said amplitude adjustment based on a previously configured target amplitude level received at the UE.

[0151] Item 9. The method of any preceding item, wherein said amplitude configuration comprises a value of said target amplitude level or of an adjustment of the target amplitude value.

[0152] Item 10. The method of any preceding item, wherein the TRP is configured to control transmission by precoding.

[0153] Item 11. The method of any preceding item, wherein the TRP is configured to transmit the amplitude adjustment configuration based on a connectivity change between said TRP and at least one UE.Item 12. The method of item 11, wherein said connectivity change comprises a change in transmit power of said downlink channel from said TRP.

[0154] Item 13. The method of item 11 wherein said connectivity change comprises added or dropped connection of at least one UE to the TRP.

[0155] Item 14. The method of any preceding item, wherein the amplitude adjustment configuration comprises a trigger for the UE to estimate the amplitude adjustment.

[0156] Item 15. The method of item 1 or 14, wherein the amplitude adjustment configuration comprises configuration of a downlink reference signal transmitted by the TRP, wherein the reference signal is usable for the UE to estimate the amplitude adjustment.

[0157] Item 16. The method of item 14 or 15, wherein the TRP is configured to transmit the reference signal upon foreseeing a change in the target amplitude level of receiving the downlink channel at said UE.

[0158] Item 17. The method of item 15 or 16, wherein the reference signal is dedicated to said UE.

[0159] Item 18. The method of any of items 15-17, wherein the reference signal is a demodulation reference signal, DMRS.

[0160] Item 19. The method of any of items 15-18, wherein the amplitude adjustment configuration comprises a message indicative of applied repetition rate of the reference signal, transmitted upon changing the repetition rate.

[0161] Item 20. The method of item 19, comprising dynamically controlling the repetition rate.

[0162] Item 21. The method of any of items 15-18, wherein transmitting (707) the amplitude adjustment configuration comprises:

[0163] transmitting (711) a configuration of a downlink reference signal transmitted by the TRP, wherein the reference signal is usable for the UE to estimate the amplitude adjustment; and

[0164] transmitting (717), upon changing repetition rate of the reference signal, a message indicative of applied repetition rate to the UE

[0165] Item 22. The method of any of items 1-14, comprising:

[0166] transmitting (711), to the UE, configuration of transmission of a reference signal by the TRP for channel estimation by the UE;

[0167] dynamically controlling (715) repetition rate of the reference signal;transmitting (717), upon changing repetition rate based on the dynamic controlling, a message indicative of applied repetition rate to the UE.

[0168] Item 23. The method of item 22, wherein the repetition rate is indicative of repetition in the time domain.

[0169] Item 24. The method of item 22 or 23, wherein the repetition rate is dynamically controlled based on a level of variance of transmit power of the TRP.

[0170] Item 25. The method of item 23 or 24, wherein the repetition rate is dynamically controlled based on a level of variance of transmit power to maintain constant amplitude levels to all UEs configured to receive transmission from said TRP

[0171] Item 26. The method of item 24 or 25, wherein said level of variance is an anticipated level of variance.

[0172] Item 27. The method of item 26, wherein said anticipated level of variance is based on a connectivity change between said TRP and at least one UE.

[0173] Item 28. The method of any of items 23-27, wherein the repetition rate is dynamically controlled dependent on a rate of transmitting amplitude adjustment configuration.

[0174] Item 29. The method of any of items 23-28, wherein the reference signal is configured for said UE.

[0175] Item 30. The method of any of items 23-29, wherein said reference signal is a demodulation reference signal, DMRS.

[0176] Item 31. The method of any preceding item, wherein the network is configured to provide synchronized signal transmission from a plurality of TRPs, including said TRP, to said UE in a common set of time-frequency resources.

[0177] Item 32. A network node (300) of a wireless network (100), wherein said network node is configured to control at least one Transmit / Receive Point, TRP, which comprises an antenna array (314) including multiple antennas, wherein the network node comprises:

[0178] logic circuitry (310) configured to control the at least one TRP to transmit, to a first User Equipment, UE, an amplitude adjustment configuration,

[0179] wherein said amplitude adjustment configuration is indicative of a target amplitude level of receiving a downlink channel at said UE from said TRP.

[0180] Item 33. The network node of item 32, wherein the logic circuitry is further configured to control the network node in accordance with any of items 2-31.

Claims

1. 22CLAIMS1. A method carried out in a wireless network comprising at least one Transmit / Receive Point, TRP, wherein said TRP comprises an antenna array including multiple antennas, said method comprising:transmitting (707), to a first User Equipment, UE, an amplitude adjustment configuration,wherein said amplitude adjustment configuration is indicative of a target amplitude level of receiving a downlink channel at said UE from said TRP.

2. The method of claim 1, wherein the TRP is configured to control transmission of the downlink channel to promote constant reception over time at said UE at said target amplitude level as adjusted based on the amplitude adjustment configuration.

3. The method of any claim 1 or 2, wherein said amplitude adjustment configuration is indicative of an adjustment of a previously configured target amplitude level.

4. The method of any preceding claim, wherein said amplitude adjustment configuration is indicative of a stepwise adjustment of the target amplitude level.

5. The method of any preceding claim, wherein said amplitude adjustment configuration is indicative of a relative adjustment of the target amplitude level.

6. The method of any preceding claim, wherein said amplitude adjustment configuration is indicative of a magnitude of adjustment of the target amplitude level.

7. The method of any of claims 3-6, wherein said amplitude adjustment configuration comprises an ID of the TRP for which the amplitude adjustment applies.

8. The method of any of claims 3-7, further comprising:computing (705) said amplitude adjustment based on a previously configured target amplitude level received at the UE.

9. The method of any preceding claim, wherein said amplitude configuration comprises a value of said target amplitude level or of an adjustment of the target amplitude value.

10. The method of any preceding claim, wherein the TRP is configured to control transmission by precoding.

11. The method of any preceding claim, wherein the TRP is configured to transmit the amplitude adjustment configuration based on a connectivity change between said TRP and at least one UE.

12. The method of claim 11, wherein said connectivity change comprises a change in transmit power of said downlink channel from said TRP.

13. The method of claim 11 wherein said connectivity change comprises added or dropped connection of at least one UE to the TRP.

14. The method of any preceding claim, wherein the amplitude adjustment configuration comprises a trigger for the UE to estimate the amplitude adjustment.

15. The method of claim 1 or 14, wherein the amplitude adjustment configuration comprises configuration of a downlink reference signal transmitted by the TRP, wherein the reference signal is usable for the UE to estimate the amplitude adjustment.

16. The method of claim 14 or 15, wherein the TRP is configured to transmit the reference signal upon foreseeing a change in the target amplitude level of receiving the downlink channel at said UE.

17. The method of claim 15 or 16, wherein the reference signal is dedicated to said UE.

18. The method of any of claims 15-17, wherein the reference signal is a demodulation reference signal, DMRS.

19. The method of any of claims 15-18, wherein the amplitude adjustment configuration comprises a message indicative of applied repetition rate of the reference signal, transmitted upon changing the repetition rate.

20. The method of claim 19, comprising dynamically controlling the repetition rate.

21. The method of any of claims 15-18, wherein transmitting (707) the amplitude adjustment configuration comprises:transmitting (711) a configuration of a downlink reference signal transmitted by the TRP, wherein the reference signal is usable for the UE to estimate the amplitude adjustment; andtransmitting (717), upon changing repetition rate of the reference signal, a message indicative of applied repetition rate to the UE22. The method of any of claims 1-14, comprising:transmitting (711), to the UE, configuration of transmission of a reference signal by the TRP for channel estimation by the UE;dynamically controlling (715) repetition rate of the reference signal; transmitting (717), upon changing repetition rate based on the dynamic controlling, a message indicative of applied repetition rate to the UE.

23. The method of claim 22, wherein the repetition rate is indicative of repetition in the time domain.

24. The method of claim 22 or 23, wherein the repetition rate is dynamically controlled based on a level of variance of transmit power of the TRP.2525. The method of claim 23 or 24, wherein the repetition rate is dynamically controlled based on a level of variance of transmit power to maintain constant amplitude levels to all UEs configured to receive transmission from said TRP26. The method of claim 24 or 25, wherein said level of variance is an anticipated level of variance.

27. The method of claim 26, wherein said anticipated level of variance is based on a connectivity change between said TRP and at least one UE.

28. The method of any of claims 23-27, wherein the repetition rate is dynamically controlled dependent on a rate of transmitting amplitude adjustment configuration.

29. The method of any of claims 23-28, wherein the reference signal is configured for said UE.

30. The method of any of claims 23-29, wherein said reference signal is a demodulation reference signal, DMRS.

31. The method of any preceding claim, wherein the network is configured to provide synchronized signal transmission from a plurality of TRPs, including said TRP, to said UE in a common set of time-frequency resources.

32. A network node (300) of a wireless network (100), wherein said network node is configured to control at least one Transmit / Receive Point, TRP, which comprises an antenna array (314) including multiple antennas, wherein the network node comprises:logic circuitry (310) configured to control the at least one TRP to transmit, to a first User Equipment, UE, an amplitude adjustment configuration,wherein said amplitude adjustment configuration is indicative of a target amplitude level of receiving a downlink channel at said UE from said TRP.

33. The network node of claim 32, wherein the logic circuitry is further configured to control the network node in accordance with any of claims 2-31.

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