Method for controlling reference signal transmission from a radio network

Abstract

A method carried out in a User Equipment, UE, (10) capable of beamforming, said method comprising: transmitting (600, 602), to a wireless network (100), information indicative of a 5 desired repetition characteristic of downlink reference signals useable for reception in the UE in combination with receiving a Wake-Up Signal, WUS; receiving (605) a plurality of said reference signals, wherein reception of the reference signals according to said repetition characteristic facilitates reception of the WUS in the UE.

Description

[0001] METHOD FOR CONTROLLING REFERENCE SIGNAL TRANSMISSION FROM A RADIO NETWORK

[0002] Technical field

[0003] This disclosure relates to methods and devices in a wireless communication system, related to management of reference signals that are transmitted from a wireless network for reception in wireless terminals. Specifically, solutions are provided for facilitating control of transmission of reference signals based on beamforming capability and / or frequency operation range of a receiver architecture in a wireless terminal.

[0004] Background

[0005] 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 terminal and a network node, and various levels of operation of the network. In 3GPP documentation, a wireless terminal 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. In the so-called 4G specifications, also referred to as Long-Term Evolution (LTE), the term eNodeB (eNB) is used to denote an access node. Further systems beyond 4G network include New Radio (NR), developed to support 5G RAN.

[0006] 5G RAN is able to operate both in connection to a 4G Core network (EPC), or a 5G core network 5GC. An access node configured to operate in a 5G radio access network may be denoted a gNB.

[0007] As wireless system technology has developed, and particularly as systems have been designed for operation at higher radio frequencies, the concept of beamforming has been introduced in wireless communication. In this context, signaling and datacommunication may be carried out in distinct and spatially selective directions. In the RAN, a base station may thus be configured with an antenna array which includes a multitude of antennas, or antenna elements, wherein relative phase of the different antennas may be controlled to obtain beam steering. Additionally, UEs may be configured with more than one antenna, allowing for the UE to control its spatial sensitivity to different directions.

[0008] A UE that is fitted with an antenna system comprising a plurality of antennas which allow for beamforming may require sensing of downlink reference signals, such as synchronization signals, to allow for proper configuration of the antenna system. Meanwhile, it may be acknowledged that undue radio signaling from the RAN should be avoided since it may compete with other purposes of using the available radio resources. In the realm of UEs having different levels of capability, e.g., with respect to beamforming, control and configuration of reference signal transmission is a challenging topic.

[0009] Summary

[0010] In view of the challenges mentioned, 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.

[0011] According to one aspect, the proposed solution relates to a method carried out in a UE capable of beamforming, said method comprising:

[0012] transmitting, to a wireless network, information indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE in combination with receiving a downlink signal, such as a Wake-Up Signal, WUS.

[0013] According to another aspect, the proposed solution is related to a method carried out in an access node of a wireless network, said method comprising:

[0014] receiving, from a UE, information indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE in combination with receiving a WUS, wherein the access node is enabled to configure transmission of said reference signals based on said information.

[0015] The proposed solution provides a mechanism for ensuring that UEs may maintain proper synchronization for WUS reception, even when different WUR architectures may operate in the wireless system.Brief of the

[0016]

[0017] Fig. 1 schematically illustrates a wireless communication system providing for communication between an access node of a wireless network and a UE.

[0018] Fig. 2 schematically illustrates a UE configured to operate according to various embodiments outlined herein.

[0019] Fig. 3 schematically illustrates an access node of the wireless network, configured to operate according to various embodiments outlined herein.

[0020] Fig. 4 schematically illustrates an example of a single antenna receiver chain for a wake-up receiver.

[0021] Fig. 5A schematically illustrates an example of a multiple antenna receiver chain for a wake-up receiver configured to provide beamforming based on an envelope of sums.

[0022] Fig. 5B schematically illustrates an example of a multiple antenna receiver chain for a wake-up receiver configured to provide beamforming based on a sum of envelopes.

[0023] Fig. 6 shows a signaling diagram which depicts various steps that may be included in a method carried out by the UE and the wireless network according to various embodiments.

[0024] Fig. 7A illustrates a timing diagram of reference signal transmission configured, or suitable, for use by a single antenna configuration of a wake-up receiver in the UE.

[0025] Fig. 7B illustrates a timing diagram of reference signal transmission configured, or suitable, for use by a multiple antenna configuration of a wake-up receiver in the UE.

[0026] Fig. 8 illustrates a diagram indicating calculated bit error rate given different signal-to-noise ratio conditions, for receiving reference signals using different types of wake-up receiver architectures.

[0027]

[0028] Detailed

[0029] 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 beconstrued 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.

[0030] 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.

[0031] 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 the relevant art and will not be interpreted in an idealized or overly formal sense expressly so defined herein.

[0032] 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.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 10 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. 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 Transmission and Reception Point (TRP) including an antenna arrangement 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 10 for use in a wireless network 100 as presented herein, and for carrying out the method steps as outlined. The UE 10 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 main receiver 213a and a transmitter 213c for communicating by radio over an air interface. The UE 10 may further be configured with a separate low-power receiver 213b, operable for detecting e.g. a Wake-Up Signal (WUS), in addition to the main receiver 213a. The low-power receiver 213b is referred to herein Wake-Up Receiver (WUR) but may optionally be called LP-WuRx or a low-power wake-up radio. Various aspects and examples of the WUR will be described further below. In some embodiments, the receiver function 213b need not be a separate receiver, but rather a configuration of the main receiver 213a for reduced function or operation.

[0035] The UE 10 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 configuredto employ an anisotropic sensitivity profile of the antenna system to communicate radio signals in a particular direction, so called beam steering.

[0036] The UE 10 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.

[0037] 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 application-specific 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.

[0038] 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 10 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.

[0039] Obviously, the UE 10 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.

[0040] Fig. 3 schematically illustrates a radio node in the form of an access node 120 of the wireless network 100 as presented herein, and for carrying out the method steps asoutlined. In various embodiments, the access node 120 is a base station for operation in the radio communication network 100, to serve one or more UEs, such as the UE 10.

[0041] The access node 120 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 transmitter for communicating through at least an air interface.

[0042] The access node 120 further comprises logic circuitry 310 configured to control the access node 120 to communicate with the UE 10 via the radio transceiver 313 on a physical channel 150.

[0043] 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 application-specific 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.

[0044] 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.).

[0045] 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 access node 120 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.

[0046] The access node 120 may further comprise, or be connected to, an antenna 314, which may include an antenna array. The logic 310 may further be configured to controlthe radio transceiver to employ an anisotropic sensitivity profile of the antenna array to transmit radio signals in a particular transmit direction. The access node 120 may further comprise an interface 315, configured for communication with the core network 110. Obviously, the access node 120 may include other features and elements than those shown in the drawing or described herein, such as a power supply and a casing etc.

[0047] In the technical field of wireless communication, energy consumption is a factor that needs to be addressed. In particular, there is a desire to obtain moderation of energy consumption, often referred to as power consumption, in the UEs, inter alia to alleviate battery capacity and / or charging requirements. Several power consumption reduction techniques have been standardized over the years. Discontinuous Reception (DRX) operation of UEs has been in effect for a long time. For non-connected UEs, which may refer to RRC_Idle or RRC_Inactive, Paging Occasion (PO) monitoring DRX configuration (commonly referred to as idle mode DRX) provides a DRX cycle which may be identical to the paging cycle. At each DRX Active time, the UE wakes up and synchronizes to decode a channel to determine if paging has been transmitted for the UE. If paging is detected, the UE may proceed according to legacy behavior to connect to the transmitting radio network node. If not, the UE deactivates monitoring and returns to sleep for a DRX cycle.

[0048] To further address energy conservation, WUS, i.e., Wake-Up Signal, was included in 3GPP release 15 for LTE. WUS is a mechanism designed for energy saving, mostly in Idle mode. In Idle mode, UEs are supposed to wake up periodically based on a Discontinuous Reception (DRX) cycle and a UE-specific Paging Occasion (PO) setting, since it is necessary to receive paging messages. Since it would be a waste of energy, using a power-hungry receiver, if a UE needs to wake up at every PO also when there is no paging for the UE, the WUS mechanism was introduced to inform the UE saying that there will be a paging for you very soon. It implies that the UE may not need to wake up for monitoring paging if there is no WUS detected and, thereby, save power. The concept was also brought to 5G, alias NR. In NR, WUS was designed into a downlink control message (DCI format 2_6) masked by a PS-RNTI (Power Save Radio Network Temporary Identifier) indicating a UE group to be paged in the subsequent DRX-On period.

[0049] Further improvement of energy saving within the concept of WUS are being considered, e.g., related to extended low power wake up signals designed to furtherreduce power consumption. Both signal design and receiver architecture for such extended low power wake up signals have been specified with the target to further reduce the UE power consumption. This approach evaluates more aggressive signal designs and architectures where the signal is agreed to be based on on-off keying with overlaid OFDM (Orthogonal frequency-division multiplexing) signal. This is, inter alia, based on a study concluded in 3GPP document TR 38.869 where several ideas of WUS and reference architecture for WUR are evaluated. The study is conducted in an agnostic way when it comes to frequency ranges and focuses on frequency range 1 (FR1, 410 MHz – 7125 MHz) as priority, however, FR2 (24250 MHz – 71000 MHz) is not precluded. In FR1, omnidirectional antennas are assumed, where in FR2, due to the shorter wavelength, more antennas are usually required to achieve a bigger antenna aperture, and also beamforming. Unless the direction between the transmitter (i.e., the UE in uplink) and receiver (access node) is known and fixed, beamforming requires beam steering, i.e., the beam angle can be changed by SW. This beam steering will require overhead in the device, which for a dedicated WUR in many cases imposes an unpractical high energy consumption. This fact is one of the reasons why FR2 has been down prioritized for the WUR. Even so, there are applications where the high frequency (e.g., FR2) WUR may be the best, or the only choice. For example, when only FR2 is available, or the operator only disposes of those frequencies. It could for example be used in fixed wireless access (FWA) equipment, in industry sensor applications, private networks etc. Besides the frequency ranges FR1 and FR2, frequencies between FR1 and FR2 may also be relevant for wireless services, e.g., at radio spectrum for IMT (International Mobile Telecommunications) at 4400 to 4800 MHz, 7125 to 8400 MHz and 14800 to 15350 MHz. In such frequency ranges it may be considered whether it is practical to use an “FRl-like” omni-directional antenna arrangement, or “FR2-like” antenna arrangements configured for beamforming. This may also depend on the application or use case, and device type.

[0050] Various aspects of the proposed solution will be outlined going forward with reference to the drawings.

[0051] According to one aspect, the proposed solution includes a method carried out in a UE 10 capable of beamforming, said method comprising:transmitting, to a wireless network, information indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE in association with configuring the beamforming.

[0052] According to another aspect, the proposed solution includes a method carried out in an access node 120 of a wireless network 100, said method comprising:

[0053] receiving, from a UE 10, information indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE for configuring the beamforming,

[0054] wherein the access node is enabled to configure transmission of said reference signals based on said information.

[0055] The proposed solution further relates to a UE 10, comprising:

[0056] a transceiver 213;

[0057] an antenna system 214, connected to the transceiver, wherein said antenna system comprises a plurality of antennas which are enabled for beamforming to receive radio signals; and

[0058] logic circuitry 210 configured to control the transceiver to transmit, to a wireless network, information indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE.

[0059] Additionally, the proposed solution relates to an access node 120 of a wireless network 100, comprising:

[0060] a transceiver 313;

[0061] an antenna system 314, connected to the transceiver, wherein said antenna system comprises a plurality of antennas which are enabled for beamforming to transmit radio signals; and

[0062] logic circuitry 310 configured to control the transceiver to receive, from a user equipment, UE, information indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE,

[0063] wherein the access node is enabled to configure transmission of said reference signals based on said information.

[0064] Going forward, various aspects of the proposed solution will predominantly be discussed and presented with reference to operation of WUR, i.e., WUS receivers. Further aspects will be outlined with reference to UE operation in higher frequency bands, such as the 7-24 GHz band.If WUS is used at higher frequencies, such as cm or mm wave of FR2, it can be expected that the WUR 213b will be equipped with multiple antennas to obtain array gain to ensure the coverage of the WUS is comparable with other NR signals. A WUR with multiple antennas may, however, be implemented in many ways. Which type of receiver that is optimal depends on the propagation environment. Further, different architectures may have different need of reference signaling from the network.

[0065] To this avail, various examples of the proposed solution provide a method carried out in the UE 10, which is capable of beamforming, wherein said method comprises transmitting, to the wireless network 100, information indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE in combination with receiving a WUS.

[0066] From the aspect of the wireless network 100, a method is provided which is carried out in an access node 120 of the wireless network 100, said method comprising receiving, from the UE 10, information indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE in combination with receiving a Wake-Up Signal, WUS. This way, the access node is enabled to configure transmission of said reference signals based on said information.

[0067] In various examples, actual configuration of the transmission of said reference signals may be selectively carried out by the access node to meet the desired repetition characteristic, or to adhere to the highest desired repetition characteristic of UEs in the coverage area of the access node, or to the desired repetition characteristic of most UEs in the coverage area, or in response to a WUS being transmitted by the access node. In some examples, the access node is in control of the configuration of the reference signal including its repetition characteristic, wherein the access node being enabled to configure transmission of said reference signals based on said information does not mean that it is required to adhere to the desired repetition characteristic.

[0068] In some examples, the downlink reference signals are usable for configuring beamforming in the UE 10, e.g., so as to identify and find the optimal beam of the UE 10 for receiving WUS. In this context, the reference signals may be referred to as synchronization signals, such as low-power synchronization signals (LP-SS).

[0069] In some examples, the WUR 213b receiver may be configured with a static implementation to use analog beamforming. Due to the need for obtaining the optimal beam for receiving the WUS, the WUR 213b may transmit information indicative of adesired repetition characteristic of the downlink reference signals, or synchronization signals, wherein said information may provide a request or indication of a certain density in time of the reference signals. This transmission of said information may be carried out once to the wireless network 100, e.g., during initial setup or registration. The information may be included in UE Radio Capabilities for the UE 10.

[0070] The purpose of requesting / indicating a desired repetition characteristic, such as density, is to enable the receiver, such as the WUR 213b, to measure the Reference Signal Received Power (RSRP) or Signal to Interference & Noise Ratio (SINR) of the reference signal on different beams and find the best beam pair to receive the WUS. This density depends on the implementation and on the number of onboard antennas. These properties are not known in advance to the network 100, which calls for said indication.

[0071] In some examples, the WUR 213b may be adaptable so that it can select the most appropriate architecture for the current propagation characteristics. By way of example, if approximately equally strong signals are detected to arrive at each WUR receive antenna port, a configuration or architecture where envelopes of signal sums are obtained (as will be described by reference to the example of Fig. 5A) may be more favorable. On the other hand, where unequally strong signals are detected at different each WUR receive antenna ports, it may be more favorable to use a configuration or architecture where a sum of envelopes is obtained (as will be described by reference to the example of Fig. 5B). The determination of which architecture to use may be determined and controlled in different ways. By way of example, the main receiver 213a may be capable of detecting the strength of the signals arriving at each of the antenna ports of the WUR receiver 213b, provided that the main receiver 213a can infer properties of the signals detected by the WUR receiver 213b, and is able to configure the WUR receiver 213b to employ the selected architecture. Another example may involve the WUR receiver 213b trying the two methods and, over time, collect statistics, and be configured to determine which of the two methods that should be applied based on the statistics. Where the WUR 213b is adaptable to select architecture, the UE 10 would need to dynamically send the indication from the preceding bullet, i.e., information indicative of a desired repetition characteristic of the downlink reference signals.In some embodiments, a combination of the two foregoing examples is employed. The UE 10 may thus be configured to transmit information indicative of a desired repetition characteristic, e.g., as UE capability information, wherein the preferred density of the reference signal transmission is indicated. Moreover, the UE 10 may transmit a message to request that downlink reference signal transmission is based on said information, e.g., when the UE makes use of a WUR architecture for analog or hybrid beamforming.

[0072] Going forward, a more detailed description is provided of how a multi-antenna WUR 213b may be implemented, and why the need for reference signaling is different. These arguments are highly mathematical but will be briefly summarized while the full analysis is provided later in the description.

[0073] It is instructive to first revisit an example of WUR implementation for a single antenna, as shown in Fig. 4. While other implementations are possible, the one in Fig. 4 allows for lower-power lower-complexity reception (at possibly higher noise figure). As shown in Fig. 4, the envelope of the incoming signal is first produced (followed by a low pass filter, which is left out in the drawing). Based on the envelope, a 1 -bit Analog-to-Digital Converter (ADC) forms a sequence of 0s / 1s, which are fed into a correlator. The correlator may in some examples comprise a shift register. In some examples, the shift register may be a Linear-Feedback Shift Register, LFSR, wherein taps of the LFSR are selected from the signal pattern of the WUS. This way, the WUR may determine whether a WUS to wake up (the main receiver 213a) is received or not.

[0074] In the context of the proposed solution, the UE 10 may, at least optionally, be configured to operate such that the WUR 213b makes use of multiple antennas.

[0075] Examples are indicated in Figs 5 A and 5B. Herein, two antennas are shown for each configuration by way of example, but that could easily be extended to any higher number of antennas or antenna ports. There are essentially two possibilities:

[0076] Implementation 1) first sum the signals at the two antennas, and then feed the sum to the envelope box, as indicated in Fig. 5A, or

[0077] Implementation 2) create the envelope per antenna and then sum the two resulting envelopes, as indicated in Fig. 5B.

[0078] In implementation 1) the antenna observations are phase shifted and then summed. The role played by the phase shifts is to prevent the two antenna observations to superimpose destructively. This is the beamforming principle, used widely in multiantenna systems and therefore not described in detail herein. For implementation 1) to be meaningful, it is key that the phase shift values are selected carefully. The phases, obtained by the phase shifters, shall be such that array gain in the spatial direction of interest is obtained, i.e., that signals from antennas add coherently. In a worst-case scenario, cancelation may actually null the received signal such that it cannot be detected.

[0079] However, even when assuming that said phase shifts are optimally selected, it can nevertheless then be shown that implementation 1) is not always better than implementation 2) in terms of performance. This is described in the mathematical explanation, provided further below. In fact, whenever the SNRs (Signal-to Noise Ration) per antenna differ substantially, implementation 2) typically yields superior performance. Further, when the SNRs per antenna are about the same, the gain of 1) over 2) is low-to-moderate (about 1 dB with 2-4 antennas, which is industry standard).

[0080] This is a noteworthy result. Even though implementation 1) builds upon beamforming - which usually produces major gains - and that it brings about the overhead penalty of estimating the optimal phase shifts, it is in some cases inferior to implementation 2) where no such estimation is needed. It is foreseeable that some UE vendors would choose implementation 2) due to its inherent simplicity, while others would choose implementation 1) since, in many use cases, the SNRs per antenna can be expected to not differ substantially. A situation in which the SNRs may differ would be if antennas are spread out across the device to increase spherical coverage. Yet another alternative is that the WUR 213b is flexible so that both 1) and 2) are supported and activated depending on current channel conditions. For example, If the SNR is the same use 1), but if, e.g., a user of the UE 10 puts his hand over one antenna, which will change the ’’channel condition”, use 2). It may further be noted that, with reference to implementation 2), the UE 10 may at some point be configured to receive data in connected mode, and then another receiver branch with phase shifter may be connected to the antennas. However, during Wakeup for implementation 2, phase shifters would not help at all. In fact, the presence of phase shifters (usable in connected mode) does not influence the performance. Even if such phase shifters are connected to the antennas, they do not need to be bypassed, they could be there but will play no role whatsoever. In other words, the implementation 2) approach is fully compatible and any setting on the phase shifters will work.For a WUR architecture according to implementation 1) the task of phase configuration needs to be considered, where tuning of the phase shifters is carried out. This turns out to be a challenging problem when the WUS time of arrival is unknown. As a WUR cannot buffer an incoming signal, transmitting reference symbols prior to the WUS is not a viable solution. Such reference symbols would also have unknown positions, which basically eliminates their role. To illustrate, assume that the WUR knows that reference symbols appear T seconds earlier than the WUS. The WUR must then guess the starting position of the reference symbols, tune its phase shifts accordingly, and then await the entire WUS. If no strong peaks are observed, then one cannot conclude that there is no WUS. It may just have been so that the phase shifts were incorrectly tuned since the initial guess was wrong; the reference signals may have appeared T_0 seconds after the guess. But now it is too late to retune the phase shifts, as the signal has not been buffered and is “gone”.

[0081] Fortunately, there are more signals to be read by the device than merely the WUS itself. On a periodic basis, there are reference signals in the form of synchronization signals (also referred to as sync signals) broadcasted by the network 100. The UE 10 may use these to acquire a rough estimate of where the WUS may appear - rough since the WUR 213b has a very poor internal clock and may lose synchronization slightly before the WUS arrives. The reference signal may be designed with the same low-complexity modulation such as On-OFF Keying (OOK) to allow low-power low-complexity reception as the ones presented in Fig. 5A-B. A multi antenna WUR 213b will need further sync signals, i.e., a plurality of sync signals such as an M-fold number. Here, said plurality, e.g., M, may refer to the number of receive configurations of the receiver 213b, the number of configurable receive beams, the number of spatial filters, the number of spatial configurations, the number of obtainable spatial beams, the number of antenna ports, the number of antennas, or the number of antennas or antenna ports divided by number of receiver chains. During these plurality (e.g., M) synchronization signals the UE 10 may conduct a beam sweep and tune its phase shifters as shown in implementation 1) according to the strongest received signal. In this way, the phase shifts are accurately tuned when the WUS appears.

[0082] A problem that arises is that the WUR has, as mentioned, bad clock accuracy and needs to probe every synchronization signal to stay tuned. This does not allow for a receive beam sweep like what is possible in connected mode. A viable solution wouldbe that a reference signal is added to the transmission of each sync signal (in each TRP beam). This would allow the UE to perform a power measurement to support it’s receive beam selection. The algorithm in the UE side, e.g., which receive-beam to select for testing etc., will most likely be non- standardized and be left up to implementation in a similar fashion as conventional UE receive beam selection in FR2.

[0083] A problem associated with state of the art signaling is thus that the UE may be unable to establish its beam, based on already existing sync / reference signals, because the UE cannot change its beam / phases as it needs to read every sync signal to maintain time-sync. For example, if the UE would change its beam to a candidate beam to see if this is better than its current beam, then it may happen that it totally misses the sync signal as the candidate beam was wrong. In that case, it cannot read the next sync signal as it may have lost time- sync.

[0084] For this reason, in some examples, the proposed solution entails that an already existing reference signal, such as an existing sync signal, for allowing the UE to stay in sync with the access node, is complemented with additional reference signal transmissions that can be used for estimating optimal phase shifts in the UE. This can be done based on adding one or more repetitions of a reference signal that is different from the existing sync signal, or by configuring further occasions, or copies, of the existing sync signal. In other words: the existing, legacy, sync signal is used to maintain sync with the access node, whereas the reference signal transmission proposed herein is added to enable the UE to tune the phase shifters, to facilitate reception of the WUS.

[0085] According to the proposed solution, where the UE 10 is configured to use a WUR 213b architecture with multiple antennas operating according to implementation 1), the UE 10 may indicate to the network 100 that it requires an N-fold of reference signals (for use as synchronization signals). Here, the number N may typically be N=M, where M represents at least one of the number of receive configurations of the receiver 213b, the number of configurable receive beams, the number of spatial filters, the number of spatial configurations, the number of obtainable spatial beams, the number of antenna ports, the number of antennas, and the number of antenna ports divided by the number of receiver chains, with separate phase shifters. However, the UE 10 need not be forced to identify M, or the network 100 need not adhere to the number M is indicated by the UE 10. In general, there proposed solution may result in both N> M and N< M) of sync signals. By way of example, if the UE 10 has 4 antenna ports and senses strong signal itmay be ok with 1 or 2 synch signals and may request that. Alternatively, the UE 10 may signal a request for N=4 synch signals, but dependent on other factors, such as network load and resource requirements for other UEs, the network 100 may deny the increase, or deny the increase to 4 but allow a smaller increase, such as transmission of of 3 synchronization signals. As noted, this indication may be dynamic for devices with flexible implementations, wherein a message or other indication may be transmitted from the UE 10 when it is configured to use the WUR architecture with M antenna ports divided by number of receiver chains.

[0086] Fig. 6 schematically illustrates a signaling diagram which covers various examples of the proposed solution. The diagram depicts signaling or message transactions between the wireless network 100 and the UE 10. In this context, it may be noted that such radio signals are transmitted from and received by RAN of the network, such as one or more access nodes 120. However, it may be noted that information provided by the UE 10 as UE capability information may at one point be conveyed to one access node, whereas information which is dynamically transmitted by the UE to indicate a request or preference to receive a desired repetition characteristic, may subsequently be transmitted to another access node. Furthermore, the reference signals (labelled synch signals in the drawing) may be transmitted from a plurality of access nodes of the network 100. According to one example, step 600 indicates that the UE 10 transmits, to the network 100, information 60 indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE 10 in combination with receiving WUS.

[0087] In step 601, an access node 120 of the network 100 receives, from the UE 10, the information indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE 10 in combination with receiving a WUS.

[0088] Thereby, the access node 120 is enabled to configure or control transmission of said reference signals based on said information.

[0089] Based on these actions, the UE 10 is enabled or configured to subsequently receive (605) a plurality of said reference signals, wherein said repetition characteristic facilitates beam-based reception of the WUS in the UE 10.

[0090] In some embodiments, use of the reference signal reception in the UE 10 may comprise any combination of the following examples.According to some examples, reception of the plurality of said reference signals from an access node 120 of the network enables or controls the UE 10 to configure the WUR 213b for beam-based reception of the WUS from said access node 120.

[0091] According to some examples, reception of the plurality of said reference signals enables or controls the UE 10 to configure a receive configuration of the WUR 213b for beam-based reception of the WUS.

[0092] According to some examples, reception of the plurality of said reference signals enables or controls the UE 10 to determine an optimum receive configuration of the WUR 213b and to apply said receive configuration for beam-based reception of the WUS.

[0093] According to some examples, reception of the plurality of said reference signals enables or controls the UE 10 to configure a receive configuration of the WUR 213b to one of a number of obtainable spatial configurations, for beam-based reception of the WUS.

[0094] According to some examples, reception of the plurality of said reference signals enables or controls the UE 10 to configure the WUR 213b to a receive configuration in which strongest reference signal reception is obtained, for beam-based reception of the WUS.

[0095] According to some examples, the UE 10 is enabled or controlled to tune phase shifters of the WUR 213b between occasions of reception of the plurality of reference signals, to determine a receive configuration of the WUR 213b for beam-based reception of the WUS.

[0096] In some examples, said information 60 is transmitted as UE capability information. According to the established art, once the UE 10 has registered with the network 100 and provided at least an indication of its UE capabilities, the UE capabilities may be stored in or in connection to the network 100, and the network 100 may use the stored information for the UE 10 in question whenever the UE 10 reconnects to the network 100. In other examples, the information 60 may be transmitted from the UE 10 in message which is separate from the exchange of UE capabilities. The information 60 may be configured to indicate in combination of the examples set out below.

[0097] In some examples, said information 60 is indicative of capability of analog beamforming in the UE 10. In some examples, the information of capability of analogbeamforming may be indicative of a type or level of beamforming capability. In some examples, the information 60 is specifically indicative of analog beamforming capability of a WUR 213b included in the UE 10, according to one or more of the examples set out below.

[0098] In some examples, the information of capability of analog beamforming may be indicative of included number M of antennas in the UE 10, e.g., connected to the WUR 213b.

[0099] In some examples, the information of capability of analog beamforming is indicative of included number M of antenna ports divided by number of radio frequency, RF, receiver chains in the UE, e.g., connected to the WUR 213b.

[0100] In some examples, the repetition characteristic indicated by the said information 60, is indicative of a preferred minimum number N of repetitions of reference signal transmission. In some examples, this may indicate a request, or preference, of receiving an N-fold number of reference signals.

[0101] In some examples, said repetition characteristic is indicative of a preferred minimum number N of repetitions of reference signal transmission during a certain time period.

[0102] In some examples, said repetition characteristic is indicative of a preferred minimum number N of repetitions of reference signal transmission during a time period in conjunction with WUS transmission, such as before or overlapping a configured time period for WUS transmission.

[0103] In some examples, said reference signal has an associated periodicity, and wherein said repetition characteristic is indicative of a preferred minimum number N of repetitions of reference signal transmission per period.

[0104] In some examples, said repetition characteristic is indicative of a number N of repetitions within a time period associated with a discontinuous reception period.

[0105] In some examples, the number N equals said number M or is a function of M. In some examples, said repetition characteristic is indicative of a required time gap between successive repetitions of said reference signal transmissions. Such a time gap may be required for proper operation of the WUR 213b, e.g. to provide sufficient time for adjusting phase shifters between successive reference signal transmissions.In some examples, the information 60 may be associated with an identified type of reference signals, such as synchronization signals configured for synchronization of a WUR 213b.

[0106] In some examples, the information 60 may be associated with a synchronization signal, wherein reception of the reference signals is usable for tuning the phase shifters in the WUR 213b to facilitate WUS reception in the UE 10.

[0107] In some examples, said downlink reference signals are usable for phase tuning in the UE 10 upon analog or hybrid beamforming, such as phase tuning of signals from the antennas to obtain coherent reception in a receiver chain of the UE 10.

[0108] In some examples, each occasion of reference signal transmission comprises an access node beam sweep.

[0109] As already noted, The UE 10 may have capability to selectively use analog beamforming, e.g., according to implementation 1), wherein a plurality M of antennas are connected to the, or each, receiver chain in the WUR 213b. Such selective use may be based on, e.g., current channel properties and / or the frequency range offered for WUS by the network 100. This has been discussed in the foregoing in the context of as dynamically transmitting an indication. In such examples, the UE 10 may be configured to transmit 602 a message 61, to request that downlink reference signal transmission is based on the provided information 60. Correspondingly, the access node 120 may be configured to receive 603 the message indicating a request by the UE 10 that downlink reference signal transmission is based on said information 60.

[0110] Alternatively, the information 60 according to any of the examples outlined in the forgoing and described as transmitted in step 600, may be conveyed in said message 61 rather than as a separate preceding UE capability information transaction.

[0111] In some examples, the access node may transmit 602B, in response to receiving 601 the information and / or in response to receiving 603 the message 61, a response message 61B.

[0112] The response message 61B may in some examples acknowledge receipt of the information 60 and / or the request 61.

[0113] The response message 61B may confirm that the access node will apply the N number of repetitions of reference signal transmissions requested or indicated by the UE 10.The response message 61B may in some examples identify a number N1 of repetitions of reference signal transmissions that the access node will apply, where N1 is less than a number N indicated by the UE 10.

[0114] 604 indicates transmission, by the access node 120, of the reference (synch) signals 62, wherein 605 indicates reception of the reference signals 62 in the UE 10.

[0115] In some examples, the reference signal transmission, such as the repetition character, is configured based on the received information 60.

[0116] According to some examples, the access node 120 may selectively configure repetition of the reference signal based on the information 60. As noted, the access node may be in control of the configuration of the reference signal including its repetition characteristic, including whether to and how to configure the repetition based in the information 60 received from the UE 10 one several UEs, as exemplified.

[0117] In some examples, the access node 120 may be configured to transmit 606 a WUS 63, as illustrated in the drawing. This may be based on a need to wake up one or more UEs, such as the UE 10, e.g., based on a trigger to transmit data to or request data from said UE(s). The access node may thus, for at least a time period according to any of the mentioned examples, in conjunction with the transmitting the WUS, configure repetition of the reference signal transmission 604 based on said information 60.

[0118] 607 illustrates reception of the WUS 63 in the UE 10. Based on the reception of the WUS 63, the UE 10 may monitor a PO, and optionally wake up the main receiver 213a.

[0119] Figs 7A and 7B show timing diagrams, which schematically illustrate transmission of reference signals (synch signals) which may be received and used by a WUR.

[0120] In Fig. 7A, each occasion 70 represents one reference signal transmission, e.g., an LP-SS, by a multi-antenna access node 120, where each occasion may comprise a beam sweep. A monitoring window 72 is configured for WUS detection by the UE 10. Given that clock accuracy in the WUR 213b may be coarse, the reference signals 70 may be used by the WUR 213b to maintain synchronization to monitor for WUS in the window 72.

[0121] The diagram of Fig. 7A may represent configuration of the reference signal 70 for reception and use by a UE comprising a single antenna WUR, such as in Fig. 4.In contrast, the diagram of Fig. 7B may represent configuration of a repetition characteristic of the reference signal for reception and use by the UE 10 comprising multiple antennas, such as two antennas or two antennas per receiver chain. The repetition characteristic may be configured based on the information 60 obtained from the UE 10. In this example, the repetition characteristic of the reference signal 62 is configured to be N-fold to include transmission 604 at occasions 70 and 71, where N=2, and N=M, e.g., the number of antenna ports, or antenna ports divided by number of receiver chains, in the WUR 213b of the UE 10. The diagram also indicates a time gap 73 between the transmission occasions according to the repetition characteristic. The time gap 73 may be configured based on the information received from the UE 10, as explained.

[0122] In the foregoing, the proposed solution has been described in the context of reference signal configuration for WUR use. In addition, or alternatively, the proposed solution may be used for, e.g., UEs configured to operate at 7-24 GHz. There is some consensus that multi antenna UEs may be implemented both with hybrid / analog beamforming as well as with digital beamforming. The meaning of this is that hybrid / analog beamformers have limited number of RF chains (1 for analog, few, e.g., 2 or more, for hybrid), while digital beamformer UEs have a number of RF chains that equals the number of antennas (or thereabout). A UE with digital beamforming is capable of determining its optimal beamformer from a single received reference signal. On the contrary, a UE with analog / hybrid beamforming must receive M (= number of antenna ports divided by the number of RF chains) reference signals before it can determine its optimal beamformer weights. This may be expressed as a requirement that the UE performs a so-called receive beam sweep. Thus, the same issue as for WUR emerges: some UEs, dependent on analog / hybrid beamforming architecture, need more reference signals than others. This must be indicated by the UE to the network. In this context, the repetition characteristics may in some examples refer to transmission of reference signals that may be CSI-RS (Channel State Information Reference Signal). The examples provided above with reference to what the information 60 includes or indicates, is otherwise equally applicable to this use of reference signals.

[0123] Going forward, the mentioned mathematical analysis is outlined, which provides an addition of means to estimate power associated with a WUS sync signal to aidreceive beam selection. The following relates to error probability of envelope detection with multiple antennas.

[0124] We consider a set of K antennas, each one receiving a signal

[0125] ỹk= αkx + w̃k

[0126] where x 6 {0,1}, akare arbitrary complex variables, and wkis complex Gaussian with variance No.

[0127] For later purposes, we consider the normalized variables

[0128] yk= √(2 / N0) ỹk= βkx + wk

[0129]

[0130] where βk= √(2 / N0)αkand wkis complex Gaussian with variance 2.

[0131] We next study two different architectures to demodulate the symbol x based on observations {yk}, both of which are based on energy comparisons with a threshold.

[0132] Method 1: Sum of envelopes

[0133] This may in some examples correspond to the WUR configuration of Fig. 5B, i.e., implementation 2).

[0134] This method demodulates on the basis of the rule

[0135] K

[0136] r = ∑|yk|2≷ T.

[0137]

[0138] k=l

[0139] We next determine the error probability of this rule.

[0140] Make the decompositions βk= βkR+ jβkIand wk= wkR+ jwkI. It follows that wkRand wkIare Gaussian with unit variance. We have

[0141] l

[0142]

[0143] y / cl2= \Pkx+ W / T + + w / J2.

[0144] As the noise variables are standard Gaussian, it follows that each component is a non-central chi square random variable, with 1 DoF, and non-centrality parameter 2 2

[0145]

[0146] and (βkIx)2, respectively.

[0147] The characteristic function of a noncentral chi square variable z with L DoFs, and noncentrality parameter A reads

[0148] / jtA \ 1

[0149] =exp(1_W / 2-

[0150]

[0151] Thus, φr(t), for given x, reads- K Jt(j3k ]^ expx)2\ [1

[0152] 1 — 2jt Hl - Zjt)1 / 2-k=l fjtx2^=M2\ 1

[0153]

[0154] eXPV 1 — 2jt / (1 — 2jt)K' The implication is that, conditioned on x, r is a non central chi square random variable with 2K DoFs and non centrality parameter x2∑k=1K|βk|2; this is typically notated as

[0155]

[0156] As the CDF of a non-central chi square is readily available, the probability of false alarm, i.e., the probability that r > T for x = 0, reads

[0157] PFA(T) = Pr(r > T|x = 0) = QK(0, √T), where Qν(a, b) is the generalized Marcum Q function of order ν. Likewise, the probability of a miss reads

[0158]

[0159] To find the error probability, we should solve

[0160] PFA(. V) + PM(T)

[0161] Pi = min

[0162]

[0163] T>0 2

[0164] This optimization is not possible to carry out in closed form. However, it may be strongly suspected that PFA(T) + PM(T) is unimodal, so that the optimization is trivial to do numerically.

[0165] To summarize, the error probability of method 1 reads

[0166] Q / f(o, VT) + 1 - QK

[0167] P. = min - —

[0168]

[0169] T>0 2

[0170] Method 2: Envelope of sum

[0171] This may in some examples correspond to the WUR configuration of Fig. 5A, i.e., implementation 1).

[0172] This method demodulates on the basis of the ruleK

[0173] ∑bkyk

[0174]

[0175] k=l

[0176] where bkare beamforming coefficients. Define the equivalent but normalized observation variable

[0177] K 2

[0178] 1

[0179] ^\;yk.

[0180]

[0181] k=l

[0182] so that the test reads

[0183]

[0184] k=l

[0185] It may be seen by inspection that

[0186] r = |γx + w|2

[0187] where w is complex Gaussian with variance 2, and

[0188] K

[0189]

[0190] Make the decompositions γ = γR+ jγIand w = wR+ jwI. The two noise variables are standard Gaussian. We may write

[0191] r

[0192]

[0193] = |yRx + wR|2+ |yJx + w1!2.

[0194] Thus,

[0195] r\x = 0 ~ / ^(0)

[0196] r

[0197]

[0198] \x = 1 ~ zKIrl2)- Wherefore,

[0199] PFA(r) = Pr(r > T\x = 0) = Q2(0, VT), K 2 1 PM(n = Pr(r < T\x = 1) = 1 - Qi bkpkT.

[0200]

[0201] MF k=l To summarize, the error probability of method 2 reads

[0202] P2= minT≥0(Q1(0, √T) + 1 − Q1(|1 / √∑|bk|² ∑k=1Kbkβk|, √T)) / 2

[0203]

[0204] 2 Finally, we mention that the beamforming coefficients bkmust be found and optimized for method 2. The optimal solution is, clearly, bk= βk*, in which case,P2= minT≥0(Q1(0, √T) + 1 − Q1(√∑k=1K|βk|2, √T)) / 2.

[0205]

[0206] T>0 2

[0207] Numerical results

[0208] We present one interesting case, namely, a situation in which Method 2 (implementation 1) is better than method 1 (implementation 2).

[0209] Consider K = 4 and the two setups

[0210] • Case A: |αk| = 1, ∀k and random phases for each αk. The beamforming coefficients are optimal, i.e., bk= βk*.

[0211] • Case B: |α1| = |α2| = 1, |α3| = |α4| = 0.1, and random phases for each αk.

[0212] The beamforming coefficients are optimal with respect to phase, but have constant amplitudes, i.e., bk= βk* / |βk|. Case B implies that the four antennas have different SNRs, but that the antennas are only equipped with phase shifters, not amplitude control. Thus, optimal beamforming is indeed implemented, but not MRC. The results are shown in Fig. 8, where Bit Error Rate (BER) is plotted as a function of SNR. It may be observed that method 2 is superior in Case B, but that Method 1 is optimal for Case A.

[0213] Various aspects of the proposed solution have been outlined in the foregoing. Different features and functions of such aspects may be combined in any way or form where not contradictory, and in accordance with the items set out below.

[0214] Item 1. A method carried out in a UE capable of beamforming, said method comprising:

[0215] transmitting, to a wireless network, information indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE in association with configuring the beamforming.

[0216] Item 2. A method carried out in a User Equipment, UE, (10) capable of beamforming, said method comprising:

[0217] transmitting (600, 602), to a wireless network (100), information indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE in combination with receiving a Wake-Up Signal, WUS;

[0218] receiving (605) a plurality of said reference signals,

[0219] wherein reception of the reference signals according to said repetition characteristic facilitates reception of the WUS in the UE.Item 3. The method of item 1 or 2, wherein said information is indicative of capability of analog or hybrid beamforming.

[0220] Item 4. The method of any preceding item, wherein said repetition characteristic is indicative of a preferred minimum number of repetitions of reference signal transmission.

[0221] Item 5. The method of any of items 1-3, wherein said repetition characteristic is indicative of a preferred minimum number of repetitions of reference signal transmission during a certain time period.

[0222] Item 6. The method of any of items 1-3, wherein said reference signal has an associated periodicity, and wherein said repetition characteristic is indicative of a preferred minimum number of repetitions of reference signal transmission per period.

[0223] Item 7. The method of any of items 4-6, wherein said repetition characteristic is indicative of a required time gap between successive repetitions of said reference signal transmissions.

[0224] Item 8. The method of any of items 4-7, wherein said repetition of reference signal transmission comprises a repetition of beam sweeps.

[0225] Item 9. The method of any preceding item, wherein the information is indicative of a number of antenna ports included in the UE.

[0226] Item 10. The method of any of items 1-8, wherein the information is indicative of a number of antenna ports divided by number of radio frequency, RF, receiver chains included in the UE.

[0227] Item 11. The method of any preceding item, wherein said downlink reference signals are usable for phase tuning in the UE upon analog beamforming.

[0228] Item 12. The method of any preceding item, wherein said downlink reference signals are synchronization signals configured for synchronization of a low power Wake-Up Receiver, WUR.

[0229] Item 13. The method of any preceding item, wherein transmitting comprises: transmitting (600) said information indicative of a desired repetition characteristic as UE capability information;

[0230] transmitting (602) a message (61) to request that downlink reference signal transmission is based on said information.

[0231] Item 14. A UE 10, comprising:a transceiver 213;

[0232] an antenna system 214, connected to the transceiver, wherein said antenna system comprises a plurality of antennas which are enabled for beamforming to receive radio signals; and

[0233] logic circuitry 210 configured to control the transceiver to transmit, to a wireless network, information indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE.

[0234] Item 15. A User Equipment, UE, (10) comprising:

[0235] a transceiver (213);

[0236] an antenna system (214), connected to the transceiver, wherein said antenna system comprises a plurality of antennas which are enabled for beamforming to receive radio signals; and

[0237] logic circuitry (210) configured to control the transceiver to

[0238] transmit, to a wireless network, information indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE in combination with receiving a Wake-Up Signal, WUS; and to

[0239] receive a plurality of said reference signals,

[0240] wherein reception of the reference signals according to said repetition characteristic facilitates reception of the WUS in the UE.

[0241] Item 16. The UE of item 14 or 15, wherein the logic circuitry is further configured to control the UE in accordance with any of items 2-13.

[0242] Item 17. A method carried out in an access node 120 of a wireless network 100, said method comprising:

[0243] receiving, from a UE 10, information indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE for configuring the beamforming,

[0244] wherein the access node is enabled to configure transmission of said reference signals based on said information.

[0245] Item 18. A method carried out in an access node (120) of a wireless network (100), said method comprising:

[0246] receiving (601, 603), from a User Equipment, UE, (10) information indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE in combination with receiving a Wake-Up Signal, WUS, wherein the accessnode is enabled to configure transmission of said reference signals based on said information; and

[0247] transmitting (604) a plurality of said reference signals, wherein transmission of the reference signals according to said repetition characteristic facilitates reception of the WUS in the UE.

[0248] Item 19. The method of item 17 or 18, wherein said information is indicative of UE capability of analog or hybrid beamforming.

[0249] Item 20. The method of any of items 17-19, wherein said repetition characteristic is indicative of a preferred minimum number of repetitions of reference signal transmission.

[0250] Item 21. The method of any of items 17-19, wherein said repetition characteristic is indicative of a preferred minimum number of repetitions of reference signal transmission during a certain time period.

[0251] Item 22. The method of item 18 or 19, wherein said reference signal has an associated periodicity, and wherein said repetition characteristic is indicative of a preferred minimum number of repetitions of reference signal transmission per period.

[0252] Item 23. The method of any of items 20-22, wherein said repetition characteristic is indicative of a required time gap between successive repetitions of said reference signal transmissions.

[0253] Item 24. The method of any of items 20-23, wherein said repetition of reference signal transmission comprises a repetition of beam sweeps.

[0254] Item 25. The method of any of items 17-24, wherein the reference signals according to said repetition characteristic facilitate reception of the WUS in the UE.

[0255] Item 26. The method of any of items 17-25, wherein the information is indicative of a number of antenna ports included in the UE.

[0256] Item 27. The method of any of items 17-25, wherein the information is indicative of a number of antenna ports divided number of radio frequency, RF, receiver chains included in the UE.

[0257] Item 28. The method of any of items 17-27, wherein said downlink reference signals are usable for phase tuning in the UE upon analog or hybrid beamforming.Item 29. The method of any of items 17-28, wherein said downlink reference signals are synchronization signals configured for synchronization of a low power Wake-Up Receiver, WUR.

[0258] Item 30. The method of any of items 17-29, wherein receiving comprises: receiving (601) said information indicative of a desired repetition characteristic as UE capability information;

[0259] receiving (603) a message to request that downlink reference signal transmission is based on said information.

[0260] Item 31. The method of any of items 17-30, comprising:

[0261] selectively configuring repetition of the reference signal based on said information.

[0262] Item 32. The method of item 31, wherein configuring includes configuring a number of repetitions within a time period associated with a discontinuous reception period.

[0263] Item 33. The method of any of items 17-32, comprising:

[0264] transmitting (606) a WUS;

[0265] configuring, for a time period in conjunction with the transmitting the WUS, repetition of the reference signal based on said information.

[0266] Item 34. An access node 120 of a wireless network 100, comprising:

[0267] a transceiver 313;

[0268] an antenna system 314, connected to the transceiver, wherein said antenna system comprises a plurality of antennas which are enabled for beamforming to transmit radio signals; and

[0269] logic circuitry 310 configured to control the transceiver to receive, from a user equipment, UE, information indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE,

[0270] wherein the access node is enabled to configure transmission of said reference signals based on said information.

[0271] Item 35. An access node (120) of a wireless network, comprising:

[0272] a transceiver (313);

[0273] an antenna system (314), connected to the transceiver, wherein said antenna system comprises a plurality of antennas which are enabled for beamforming to transmit radio signals; andlogic circuitry (310) configured to control the transceiver to:

[0274] receive, from a user equipment, UE, information indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE in combination with receiving a Wake-Up Signal, WUS,

[0275] wherein the access node is enabled to configure transmission of said reference signals based on said information; and

[0276] transmit a plurality of said reference signals, wherein transmission of the reference signals according to said repetition characteristic facilitates reception of the WUS in the UE.

[0277] Item 36. The access node of item 34 or 35, wherein the logic circuitry is further configured to control the access node in accordance with any of items 19-33.

Claims

CLAIMS1. A method carried out in a UE capable of beamforming, said method comprising:transmitting, to a wireless network, information indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE in association with configuring the beamforming.

2. A method carried out in a User Equipment, UE, (10) capable of beamforming, said method comprising:transmitting (600, 602), to a wireless network (100), information indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE in combination with receiving a Wake-Up Signal, WUS;receiving (605) a plurality of said reference signals,wherein reception of the reference signals according to said repetition characteristic facilitates reception of the WUS in the UE.

3. The method of claim 1 or 2, wherein said information is indicative of capability of analog or hybrid beamforming.

4. The method of any preceding claim, wherein said repetition characteristic is indicative of a preferred minimum number of repetitions of reference signal transmission.

5. The method of any of claims 1-3, wherein said repetition characteristic is indicative of a preferred minimum number of repetitions of reference signal transmission during a certain time period.

6. The method of any of claims 1-3, wherein said reference signal has an associated periodicity, and wherein said repetition characteristic is indicative of a preferred minimum number of repetitions of reference signal transmission per period.

7. The method of any of claims 4-6, wherein said repetition characteristic is indicative of a required time gap between successive repetitions of said reference signal transmissions.

8. The method of any of claims 4-7, wherein said repetition of reference signal transmission comprises a repetition of beam sweeps.

9. The method of any preceding claim, wherein the information is indicative of a number of antenna ports included in the UE.

10. The method of any of claims 1-8, wherein the information is indicative of a number of antenna ports divided by number of radio frequency, RF, receiver chains included in the UE.

11. The method of any preceding claim, wherein said downlink reference signals are usable for phase tuning in the UE upon analog beamforming.

12. The method of any preceding claim, wherein said downlink reference signals are synchronization signals configured for synchronization of a low power Wake-Up Receiver, WUR.

13. The method of any preceding claim, wherein transmitting comprises: transmitting (600) said information indicative of a desired repetition characteristic as UE capability information;transmitting (602) a message (61) to request that downlink reference signal transmission is based on said information.

14. A UE 10, comprising:a transceiver 213;an antenna system 214, connected to the transceiver, wherein said antenna system comprises a plurality of antennas which are enabled for beamforming to receive radio signals; andlogic circuitry 210 configured to control the transceiver to transmit, to a wireless network, information indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE.

15. A User Equipment, UE, (10) comprising:a transceiver (213);an antenna system (214), connected to the transceiver, wherein said antenna system comprises a plurality of antennas which are enabled for beamforming to receive radio signals; andlogic circuitry (210) configured to control the transceiver totransmit, to a wireless network, information indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE in combination with receiving a Wake-Up Signal, WUS; and toreceive a plurality of said reference signals,wherein reception of the reference signals according to said repetition characteristic facilitates reception of the WUS in the UE.

16. The UE of claim 13 or 14, wherein the logic circuitry is further configured to control the UE in accordance with any of claims 2-13.

17. A method carried out in an access node 120 of a wireless network 100, said method comprising:receiving, from a UE 10, information indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE for configuring the beamforming,wherein the access node is enabled to configure transmission of said reference signals based on said information.

18. A method carried out in an access node (120) of a wireless network (100), said method comprising:receiving (601, 603), from a User Equipment, UE, (10) information indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE in combination with receiving a Wake-Up Signal, WUS, wherein the accessnode is enabled to configure transmission of said reference signals based on said information; andtransmitting (604) a plurality of said reference signals, wherein transmission of the reference signals according to said repetition characteristic facilitates reception of the WUS in the UE.

19. The method of claim 17 or 18, wherein said information is indicative of UE capability of analog or hybrid beamforming.

20. The method of any of claims 17-19, wherein said repetition characteristic is indicative of a preferred minimum number of repetitions of reference signal transmission.

21. The method of any of claims 17-19, wherein said repetition characteristic is indicative of a preferred minimum number of repetitions of reference signal transmission during a certain time period.

22. The method of claim 18 or 19, wherein said reference signal has an associated periodicity, and wherein said repetition characteristic is indicative of a preferred minimum number of repetitions of reference signal transmission per period.

23. The method of any of claims 20-22, wherein said repetition characteristic is indicative of a required time gap between successive repetitions of said reference signal transmissions.

24. The method of any of claims 20-23, wherein said repetition of reference signal transmission comprises a repetition of beam sweeps.

25. The method of any of claims 17-24, wherein the reference signals according to said repetition characteristic facilitate reception of the WUS in the UE.

26. The method of any of claims 17-25, wherein the information is indicative of a number of antenna ports included in the UE.

27. The method of any of claims 17-25, wherein the information is indicative of a number of antenna ports divided number of radio frequency, RF, receiver chains included in the UE.

28. The method of any of claims 17-27, wherein said downlink reference signals are usable for phase tuning in the UE upon analog or hybrid beamforming.

29. The method of any of claims 17-28, wherein said downlink reference signals are synchronization signals configured for synchronization of a low power Wake-Up Receiver, WUR.

30. The method of any of claims 17-29, wherein receiving comprises: receiving (601) said information indicative of a desired repetition characteristic as UE capability information;receiving (603) a message to request that downlink reference signal transmission is based on said information.

31. The method of any of claims 17-30, comprising:selectively configuring repetition of the reference signal based on said information.

32. The method of claim 31, wherein configuring includes configuring a number of repetitions within a time period associated with a discontinuous reception period.

33. The method of any of claims 17-32, comprising:transmitting (606) a WUS;configuring, for a time period in conjunction with the transmitting the WUS, repetition of the reference signal based on said information.

34. An access node 120 of a wireless network 100, comprising:a transceiver 313;an antenna system 314, connected to the transceiver, wherein said antenna system comprises a plurality of antennas which are enabled for beamforming to transmit radio signals; andlogic circuitry 310 configured to control the transceiver to receive, from a user equipment, UE, information indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE,wherein the access node is enabled to configure transmission of said reference signals based on said information.

35. An access node (120) of a wireless network, comprising:a transceiver (313);an antenna system (314), connected to the transceiver, wherein said antenna system comprises a plurality of antennas which are enabled for beamforming to transmit radio signals; andlogic circuitry (310) configured to control the transceiver to:receive, from a user equipment, UE, information indicative of a desired repetition characteristic of downlink reference signals useable for reception in the UE in combination with receiving a Wake-Up Signal, WUS,wherein the access node is enabled to configure transmission of said reference signals based on said information; andtransmit a plurality of said reference signals, wherein transmission of the reference signals according to said repetition characteristic facilitates reception of the WUS in the UE.

36. The access node of claim 34 or 35, wherein the logic circuitry is further configured to control the access node in accordance with any of claims 19-33.

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