WO2023075650A1

WO2023075650A1 - Beam searching procedure for a user equipment

Info

Publication number: WO2023075650A1
Application number: PCT/SE2021/051073
Authority: WO
Inventors: Arne Simonsson; Niklas JALDÉN; Kjell Larsson; Anders Landström
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2021-10-25
Filing date: 2021-10-25
Publication date: 2023-05-04
Anticipated expiration: 2024-04-25

Abstract

There is provided mechanisms for performing a beam finding procedure with a network node. The method is performed by a user equipment. The method comprises obtaining directional information indicating beam directions in which the beam finding procedure is to be performed. The beam directions define a search sector. The method comprises evaluating, as part of performing the beam finding procedure, a set of candidate beams by performing a beam scan. The candidate beams that are inside the search sector are scanned more frequently than the candidate beams that are outside the search sector.

Description

BEAM SEARCHING PROCEDURE FOR A USER EQUIPMENT

TECHNICAL FIELD

Embodiments presented herein relate to a method, a user equipment, a computer program, and a computer program product for performing a beam finding procedure with a network node. Embodiments presented herein further relate to a method, a network node, a computer program, and a computer program product for assisting a user equipment to perform a beam finding procedure.

BACKGROUND

Beamforming enables directional signal transmission and reception. To change the directionality of the antenna array when transmitting, a beamformer controls the phase and relative amplitude of the signal at each individual antenna element of the antenna array in order to create a pattern of constructive and destructive interference in the wavefront.

Complexity, cost, battery consumption and spatial limitations are some motivating factors for using analog beamforming at user equipment served in the network. Analog beamforming implies that a time-wise scanning is made among available candidate beams in order for a beam pair link (BPL) to be established between a transmission and reception point (TRP) at the network-side and the user equipment at the user-side. There can be a large number of candidate beams for the user equipment to scan. As a non-limiting example, assuming that the total available number of candidate beams at the user equipment is 6o, and that in each cell the user equipment is to scan up to 64 synchronization signal block (SSB) candidates, there are 3840 combinations for the user equipment to scan in total for one cell. Further, in case the user equipment is enabled to receive SSB transmissions also from neighbor cells, the total number of combinations further increases.

Two ways for the network to assist the user equipment in finding and selecting one of the candidate beams for establishing a BPL will be summarized next. According to a first example, the user equipment keeps track of which candidate beam to use for different Transmission Configuration Indicator (TCI) states, which normally correspond to the SSBs. A new active TCI state can be assigned by the network, allowing the user equipment to switch to the candidate beam used for the corresponding TCI state. According to a second example, channel state information reference signals (CSI-RS) are repetitively transmitted from the TRP in a certain beam, allowing the user equipment to, by measuring on the CSI-RS using different ones of the candidate beams, find and select one of the candidate beams for further communication with the network via the TRP. Hence, the user equipment can be informed by the network how to change its beam quickly by the network changing between different TCI states, or the user equipment can be assisted in selecting one of the candidate beams by CSI-RS being transmitted. In any case, as a first step, the user equipment needs to keep track of which of the candidate beam to use for each SSB, not only for TCI states. One reason for this is that the user equipment, e.g., for mobility purposes also needs to keep track of other SSBs (e.g., those SSBs transmitted from a TRP of another cell).

Scanning all beam candidates takes long time. Even if TCI states are provided, the user equipment needs to keep track of updated candidate beam for the SSBs, otherwise the user equipment will not be able to find a proper beam to use without substantial scanning of all candidate beams.

SUMMARY

An object of embodiments herein is to address the above issues by providing efficient beam finding procedures.

According to a first aspect there is presented a method for performing a beam finding procedure with a network node. The method is performed by a user equipment. The method comprises obtaining directional information indicating beam directions in which the beam finding procedure is to be performed. The beam directions define a search sector. The method comprises evaluating, as part of performing the beam finding procedure, a set of candidate beams by performing a beam scan. The candidate beams that are inside the search sector are scanned more frequently than the candidate beams that are outside the search sector.

According to a second aspect there is presented a user equipment for performing a beam finding procedure with a network node. The user equipment comprises processing circuitry. The processing circuitry is configured to cause the user equipment to obtain directional information indicating beam directions in which the beam finding procedure is to be performed. The beam directions define a search sector. The processing circuitry is configured to cause the user equipment to evaluate, as part of performing the beam finding procedure, a set of candidate beams by performing a beam scan. The candidate beams that are inside the search sector are scanned more frequently than the candidate beams that are outside the search sector.

According to a third aspect there is presented a user equipment for performing a beam finding procedure with a network node. The user equipment comprises an obtain module configured to obtain directional information indicating beam directions in which the beam finding procedure is to be performed. The beam directions define a search sector. The user equipment comprises an evaluate module configured to evaluate, as part of performing the beam finding procedure, a set of candidate beams by performing a beam scan. The candidate beams that are inside the search sector are scanned more frequently than the candidate beams that are outside the search sector.

According to a fourth aspect there is presented a computer program for performing a beam finding procedure with a network node, the computer program comprising computer program code which, when run on processing circuitry of a user equipment, causes the user equipment to perform a method according to the first aspect.

According to a fifth aspect there is presented a method for assisting a user equipment to perform a beam finding procedure. The method is performed by a network node. The method comprises estimating direction towards the user equipment with respect to a transmission and reception point of the network node. The method comprises determining beam directions in which the beam finding procedure is to be performed. The beam directions define a search sector and are a function of the estimated direction towards the user equipment. The method comprises providing the directional information towards the user equipment.

According to a sixth aspect there is presented a network node for assisting a user equipment to perform a beam finding procedure. The network node comprises processing circuitry. The processing circuitry is configured to cause the network node to estimate direction towards the user equipment with respect to a transmission and reception point of the network node. The processing circuitry is configured to cause the network node to determine beam directions in which the beam finding procedure is to be performed. The beam directions define a search sector and are a function of the estimated direction towards the user equipment. The processing circuitry is configured to cause the network node to provide the directional information towards the user equipment.

According to a seventh aspect there is presented a network node for assisting a user equipment to perform a beam finding procedure. The network node comprises an estimate module configured to estimate direction towards the user equipment with respect to a transmission and reception point of the network node. The network node comprises a determine module configured to determine beam directions in which the beam finding procedure is to be performed. The beam directions define a search sector and are a function of the estimated direction towards the user equipment. The network node comprises a provide module configured to provide the directional information towards the user equipment.

According to an eighth aspect there is presented a computer program for assisting a user equipment to perform a beam finding procedure, the computer program comprising computer program code which, when run on processing circuitry of a network node, causes the network node to perform a method according to the fifth aspect.

According to a ninth aspect there is presented a computer program product comprising a computer program according to at least one of the fourth aspect and the eighth aspect and a computer readable storage medium on which the computer program is stored. The computer readable storage medium could be a non-transitory computer readable storage medium.

Advantageously, these aspects enable efficient beam finding for the user equipment.

Advantageously, the disclosed beam finding procedure avoids the above issues and enables fast and accurate evaluation of candidate beams.

Advantageously, these aspects result in faster beam management, resulting in shorter delays, improved user experience and improved over all network performance. Advantageously, these aspects require less signalling overhead, resulting in energy saves and prolonged battery life at the user equipment.

Other objectives, features and advantages of the enclosed embodiments will be apparent from the following detailed disclosure, from the attached dependent claims as well as from the drawings.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the element, apparatus, component, means, module, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, module, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

BRIEF DESCRIPTION OF THE DRAWINGS

The inventive concept is now described, by way of example, with reference to the accompanying drawings, in which:

Fig. 1, 5, 6, 7, 8, 9 and 10 are schematic diagrams illustrating examples according to embodiments;

Fig. 2 is a schematic illustration of beamforming performed at a user equipment according to embodiments;

Figs. 3 and 4 are flowcharts of methods according to embodiments;

Fig. 11 is a schematic diagram showing functional units of a user equipment according to an embodiment;

Fig. 12 is a schematic diagram showing functional modules of a user equipment according to an embodiment;

Fig. 13 is a schematic diagram showing functional units of a network node according to an embodiment;

Fig. 14 is a schematic diagram showing functional modules of a network node according to an embodiment; and Fig. 15 shows one example of a computer program product comprising computer readable means according to an embodiment.

DETAILED DESCRIPTION

The inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the inventive concept are shown. This inventive concept 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 by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. Like numbers refer to like elements throughout the description. Any step or feature illustrated by dashed lines should be regarded as optional.

Fig. 1 is a schematic diagram illustrating an example communication network 100 where embodiments presented herein can be applied. The communication network 100 could be a third generation (3G) telecommunications network, a fourth generation (4G) telecommunications network, a fifth generation (5G) telecommunications network, or any evolvement thereof, and support any 3GPP telecommunications standard, where applicable. The communication network 100 could alternatively be a non-cellular and/or a non-3GPP network, such as an IEEE 802.11 communications network, or any other wireless IEEE compliant communications network. The communication network 100 comprises a network node 300 provided in a (radio) access network 110. The network node 300 is configured to, via a transmission and reception point 140, provide network access to user equipment 200. The (radio) access network 110 is operatively connected to a core network 120. The core network 120 is in turn operatively connected to a service network 130, such as the Internet. The user equipment 200 is thereby enabled to, via the network node 300 and its transmission and reception point 140, access services of, and exchange data with, the service network 130. Examples of network nodes 300 are radio access network nodes, radio base stations, base transceiver stations, Node Bs, evolved Node Bs, gNBs, access points, and integrated access and backhaul nodes. Examples of user equipment 200 are wireless devices, mobile stations, mobile phones, handsets, wireless local loop phones, smartphones, laptop computers, tablet computers, network equipped sensors, network equipped vehicles, and so-called Internet of Things devices.

As illustrated in Fig. 1, the transmission point 140 and the user equipment 200 are configured to communicate with each other using directional beams 150, 170. In this respect, the beams 170 as used by the user equipment 200 are herein after denoted candidate beams. During a beam finding procedure the user equipment 200 performs a beam sweep, or scan, as illustrated by arrow 180, among the candidate beams 170 in order to evaluate which of these candidate beams 170 the user equipment 200 is to use for data communication with the transmission and reception point 140. Likewise, the transmission and reception point 140 also performs its own beam sweep, or scan, as illustrated by arrow 160, among the beams 150. In the illustrative example of Fig. 1 the transmission and reception point 140 is configured to sequentially use eight beams 150 and the user equipment 200 is configured to perform a scan 180 in eight candidate beams 170.

Turning now to the example of Fig. 2, there is shown a user equipment 200 equipped with four antenna panels, each configured to generate 19 candidate beams 170. The user equipment 200 of Fig. 2 might thus be configured to, during a beam finding procedure, evaluate 76 beam in total for each of the beams 150 used by the transmission and reception point 140.

In this respect, as disclosed above, there can thus be a large number of candidate beams 170 for the user equipment to scan during a beam finding procedure. According to the herein disclosed embodiments there is therefore provided mechanisms for a user equipment 200 to perform a beam finding procedure with a network node 300 and a network node 300 for assisting the user equipment 200 to perform the beam finding procedure. In order to obtain such mechanisms there is provided a user equipment 200, a method performed by the user equipment 200, a computer program product comprising code, for example in the form of a computer program, that when run on processing circuitry of the user equipment 200, causes the user equipment 200 to perform the method. In order to obtain such mechanisms there is further provided a network node 300, a method performed by the network node 300, and a computer program product comprising code, for example in the form of a computer program, that when run on processing circuitry of the network node 300, causes the network node 300 to perform the method.

With further reference to Fig. 2, according to the herein disclosed embodiments, the user equipment 200 obtains information that enables the user equipment 200 to concentrate its evaluation of candidate beams in certain beam directions that define a search sector 190. In the illustrative example of Fig. 2, the search sector covers nine out of the 76 candidate beams. As will be further disclosed below, the candidate beams 170 that are inside the search sector 190 might then be scanned more frequently than the candidate beams 170 that are outside the search sector 190.

Reference is now made to Fig. 3 illustrating a method for performing a beam finding procedure with a network node 300 as performed by the user equipment 200 according to an embodiment.

The user equipment 200 obtains directional information, as in S102.

S102: The user equipment 200 obtains directional information indicating beam directions in which the beam finding procedure is to be performed. The beam directions define at least one search sector 190.

The user equipment 200 then scans more frequently in the search sector 190 defined by the directional information, as in S106.

S106: The user equipment 200 evaluates, as part of performing the beam finding procedure, a set of candidate beams 170 by performing a beam scan. The candidate beams 170 that are inside the search sector 190 are scanned more frequently than the candidate beams 170 that are outside the search sector 190.

Embodiments relating to further details of performing a beam finding procedure with a network node 300 as performed by the user equipment 200 will now be disclosed.

In some aspects, two or more sectors are defined by the beam directions. These two or more sectors might be contiguous or non-contiguous in space.

In some aspects, the directional information that indicates beam directions in which the beam finding procedure is to be performed could instead be provided as alternative beam directions in which the beam finding procedure is not to be performed, and where candidate beams inside an alternative search sector defined by the alternative beam directions in which the beam finding procedure is not to be performed are scanned less frequently than the than the candidate beams outside this alternative search sector.

There could be different purposes for the user equipment 200 to perform the beam scan and evaluate the set of candidate beams 170 in S106. In some aspects, the purpose of the beam scan is for the user equipment 200 to locate a transmission of SSB signals. Hence, in some embodiments, each of the candidate beams 170 is used for receiving and measuring on reference signals received from the network node 300, where the reference signals are SSB signals.

In some aspects, the user equipment 200 is configured by the network node 300 to scan the candidate beams 170. Hence, in some embodiments, the user equipment 200 is configured to perform (optional) S104:

S104: The user equipment 200 receives instructions from the network node 300 to scan the candidate beams 170 that are inside the search sector 190 more frequently than the candidate beams 170 that are outside the search sector 190.

Step S106 is then performed in response to the user equipment 200 having received the instructions from the network node 300 in S104.

There may be different ways for the user equipment 200 to scan the candidate beams 170 that are inside the search sector 190 more frequently than the candidate beams 170 that are outside the search sector 190. Different embodiments relating thereto will now be described in turn.

In some aspects, that the candidate beams 170 that are inside the search sector 190 are scanned more frequently implies that these candidate beams are scanned more often in time. That is, in some embodiments, the candidate beams 170 that are inside the search sector 190 are scanned more frequently in time than the candidate beams 170 that are outside the search sector 190.

In some aspects, that the candidate beams 170 that are inside the search sector 190 are scanned more frequently implies that these candidate beams are scanned more frequently in space using, larger number of, and narrower, beams. That is, in some embodiments, a higher density of the candidate beams 170 is used when performing the beam scan inside the search sector 190 than when performing the beam scan outside the search sector 190.

In some aspects, that the candidate beams 170 that are inside the search sector 190 are scanned more frequently implies that more symbols are received in these candidate beams and then measured on. That is, in some embodiments, more symbols are received using the candidate beams 170 that are inside the search sector 190 than using the candidate beams 170 that are outside the search sector 190.

In some aspects, the candidate beams 170 that are inside the search sector 190 are scanned more frequently in time than the candidate beams 170 that are outside the search sector 190 and a higher density of the candidate beams 170 is used when performing the beam scan inside the search sector 190 than when performing the beam scan outside the search sector 190.

Aspects of the directional information will be disclosed next.

In some embodiments, the directional information is obtained by the user equipment 300 by being received from the network node 300. The directional information could originate from the network node 300 itself or be provided to the network node 300 from an entity, such as a server, in the service network 130. There could be different ways for the user equipment 200 to obtain the directional information from the network node 300. In some non-limiting examples, the directional information is obtained as system information, as radio resource control (RRC) information, as medium access control (MAC) information, as downlink control information (DCI), as handover information, or as random access channel information. The directional information might be provided as system information in a system information block (SIB) of an SSB for cell common information or in RRC signalling, or using similar protocols, for individual guiding. The direction information might be provided as handover configuration or during triggering of radio access channel signalling.

In some embodiments, the directional information is obtained by being derived by the user equipment 200 itself, i.e., without being explicitly received from the network node 300. For example, the user equipment 200 might be configured to obtain the directional information using orientation-providing information, such as information from a gyro in the user equipment 200. Further, the directional information might be specified in terms of compass directions. The compass direction might be obtained from a compass in the user equipment 200 or from the network node 300. That is, in some embodiments, the directional information is specified as a compass direction. Further, the user equipment 200 might obtain the directional information in combination from the network node 300 and internally (e.g., from the gyro and/or the compass). The orientation-providing information could enable the user equipment 200 to scan less frequently towards the ground and the sky (with directions given by the orientation-providing information) and hence to define a search sector 190 (e.g., within an elevation angle from -45⁰ to +45°) inside which the candidate beams 170 are neither pointing towards the sky, nor towards the ground. For example, the user equipment 200 might be configured to obtain the directional information using machine learning techniques using positional-providing information, cell identity information, map information, etc., as input.

There could be different examples of directional information. In some non-limiting examples, the directional information is provided as any of: bearing, elevation, sector range.

Further, the directional information might be specified in terms of absolute or relative height of the radio deployment. That is, in some embodiments, the directional information specifies a vertical height of a transmission and reception point 140 of the network node 300. The vertical height of the transmission and reception point 140 might either be the absolute height of the transmission and reception point 140 (e.g., relative sea level) or the relative height of the transmission and reception point 140 relative the user equipment 200.

Further, the directional information might be specified relatively an already used connection direction. That is, in some embodiments, the user equipment 200 has an established directive wireless link to a transmission and reception point 140 of the network node 300, and the directional information is specified in relation to a direction of the directive wireless link.

Reference is now made to Fig. 4 illustrating a method for assisting a user equipment 200 to perform a beam finding procedure as performed by the network node 300 according to an embodiment. The network node 300 indicates to the user equipment 200 to scan more frequently in a search sector 190 defined by directional information. In order to do so, the network node 300 first estimates the direction towards the user equipment 200, as in S202.

S202: The network node 300 estimates the direction towards the user equipment 200 with respect to a transmission and reception point 140 of the network node 300.

The network node 300 then determines the beam directions, as in S208.

S208: The network node 300 determines the beam directions in which the beam finding procedure is to be performed. The beam directions define a search sector 190. The beam directions are a function of the estimated direction towards the user equipment 200.

The directional information is then provided towards the user equipment 200 as in S212.

S212: The network node 300 provides the directional information towards the user equipment 200.

Embodiments relating to further details of assisting a user equipment 200 to perform a beam finding procedure as performed by the network node 300 will now be disclosed.

There may be different ways for the network node 300 to estimate the direction towards the user equipment in S202. In some aspects, the direction is estimated by means of direction-of-arrival (DoA). In particular, in some embodiments, the direction towards the user equipment 200 is estimated from DoA estimates of transmissions from the user equipment 200 towards the transmission and reception point 140.

In some aspects, the beam directions are determined based on the geographical position of the user equipment 200. In particular, in some embodiments, the network node 300 is configured to perform (optional) step S204: S204: The network node 300 obtains information of location of the user equipment 200. The beam directions might then further be determined as a function of the location of the user equipment 200.

In further aspects, the beam directions are determined based on positions of neighbouring transmission and reception points. In particular, in some embodiments, the network node 300 is configured to perform (optional) step S206:

S206: The network node 300 obtains information of locations of transmission and reception points of other network nodes. The beam directions might then further be determined as a function of the locations of the transmission and reception points of the other network nodes.

In yet further aspects, the beam directions are determined as a function of network deployment information, historically made radio measurements, modelled network performance, etc. For example, the radio measurements can be made in a different frequency band than the frequency band used during the beam finding procedure. For example, the radio measurements might have been made at a lower frequency band than the frequency band used during the beam finding procedure. That is, also the above disclosed DoA estimates might be based on measurements on radio signals in a different frequency band, such as a lower frequency band, than the frequency band used during the beam finding procedure. In this respect, the DoA estimates can be obtained based on an omnidirectional transmission from the user equipment 200 on a low frequency band, such as mid-band NEW Radio (NR) or Long Term Evolution (LTE) frequency band.

In line with what has been disclosed above with respect to the user equipment 200, in some non-limiting examples, the directional information is provided in S212 as system information, as radio resource control (RRC) information, as MAC information, as DCI, as handover information, or as random access channel information.

In line with what has been disclosed above with respect to the user equipment 200, in some non-limiting examples, the directional information is provided as any of: bearing, elevation, sector range. Further in line with what has been disclosed above with respect to the user equipment 200, the directional information might be specified in terms of absolute or relative height of the radio deployment. That is, in some embodiments, the directional information specifies a vertical height of a transmission and reception point 140 of the network node 300. The vertical height of the transmission and reception point 140 might either be the absolute height of the transmission and reception point 140 (e.g., relative sea level) or the relative height of the transmission and reception point 140 relative the user equipment 200.

Further in line with what has been disclosed above with respect to the user equipment 200, the directional information might be specified in terms of compass directions. That is, in some embodiments, the directional information is specified as a compass direction.

Further in line with what has been disclosed above with respect to the user equipment 200, the directional information might be specified relatively an already used connection direction. That is, in some embodiments, the user equipment 200 has an established directive wireless link to the transmission and reception point 140 of the network node 300, and the directional information is specified in relation to a direction of the directive wireless link.

Further in line with what has been disclosed above with respect to the user equipment 200, in some aspects, the network node 300 configures the user equipment 200 to scan the candidate beams 170. Hence, in some embodiments, the user equipment 200, as part of performing the beam finding procedure, evaluates a set of candidate beams 170 by performing a beam scan, and the network node 300 is configured to perform (optional) S210:

S210: The network node 300 instructs the user equipment 200 to scan the candidate beams 170 that are inside the search sector 190 more frequently than the candidate beams 170 that are outside the search sector 190.

Embodiments of different ways for the user equipment 200 to scan the candidate beams 170 that are inside the search sector 190 more frequently than the candidate beams 170 that are outside the search sector 190 have been disclosed above with respect to the user equipment 200. Particularly, in some embodiments, the user equipment 200 is in S210 instructed to scan the candidate beams 170 that are inside the search sector 190 more frequently in time than the candidate beams 170 that are outside the search sector 190. Further particularly, in some embodiments, the user equipment 200 is in S210 instructed to use a higher density of the candidate beams 170 when performing the beam scan inside the search sector 190 than when performing the beam scan outside the search sector 190. Further particularly, in some embodiments, the user equipment 200 is in S210 instructed to scan the candidate beams 170 that are inside the search sector 190 more frequently in time than the candidate beams 170 that are outside the search sector 190 and to use a higher density of the candidate beams 170 when performing the beam scan inside the search sector 190 than when performing the beam scan outside the search sector 190.

Some non-limiting illustrative examples based on at least some of the above disclosed embodiments and aspects will be disclosed next.

A first non-limiting example is shown in Fig. 5, where transmission and reception points 140 are deployed on rooftops of buildings. In such an example, the directional information might be provided as either the (absolute or relative) height of the buildings or some angular interval. If the transmission and reception points 140 are deployed on rooftops, candidate beams in higher elevation angles should be scanned more frequently than candidate beams in lower elevation angles.

A second non-limiting example is shown in Fig. 6, where transmission and reception points 140 are mounted on lampposts (such as streetlights). In such an example, the directional information might be provided as some angular interval. For example if the transmission and reception points 140 are mounted on lampposts the user equipment 200 can avoid scanning high elevation angles. That is, if the transmission and reception points 140 are mounted on lampposts, candidate beams in lower elevation angles should be scanned more frequently than candidate beams in higher elevation angles.

A third non-limiting example is shown in Fig. 7, where transmission and reception points 140 are deployed at street level, such as in a street canyon, or a tunnel. In a street canyon, candidate beams in directions along the street can be scanned more frequently than candidate beams in directions perpendicular into the walls on the side of the street. The directional information can be specified as the compass directions (North and South in the case in Fig. 7) so that the user equipment 200 can relate the directional information to its internal compass. The directional information might alternatively be specified relatively an already used connection direction, such as a connected cell and used beam (such as a 180-degree scanning for a transmission and reception point 140 of a neighboring cell in the opposite direction from the transmission and reception point 140 of its serving cell. For example, assuming that the user equipment 140 has a connection to the transmission and reception point 140 located in the south (“S”) direction of the user equipment 200, the directional information might specify a search space to also be in the north (“N”) direction.

A fourth non-limiting example is shown in Fig. 8, where the geographical positions of the transmission and reception points 140 are assumed to be known by the network nodes (not shown). From the geographical positions of the transmission and reception point 140 of the serving cell, the directions of transmission and reception points 140 of potential neighboring cells can be calculated and signaled to the user equipment 200, thus specifying a search sector 190 for the user equipment 200 to scan using candidate beams 170. The directional information can be provided as compass directions or relatively the direction of the transmission and reception point 140 of the serving cell.

A fifth non-limiting example is shown in Fig. 9. This example shows how the DoA of user equipment 200 with respect to transmission and reception point 140 can be determined in an urban scenario, as illustrated in Fig. 9(a), comprising buildings 910, 920, 930, 940. As shown in Fig. 9(b), where received power in dB is plotted against time, in terms of number of samples, the received power for the user equipment 200 reaches two peaks in time at A and B. Peak A is for samples that correspond to a direct path between the transmission and reception point 140 and the user equipment 200 in Fig. 9(a) and peak B is for samples that correspond to a path between the transmission and reception point 140 and the user equipment 200 as reflected at building 930 in Fig. 9(a). The measurements shown in Fig. 9(b) could have been conducted at an arbitrary frequency band. Using estimates of delays of multipath components and respective DoA, the network node 300 (not shown) can estimate possible reflection points in the environment. Given the reflection points, the DoA at the user equipment 200 can be determined. A sixth non-limiting example is shown in Fig. io. This example relates to an embodiment where the directional information is specified in relation to a direction of a known direction. Assuming that an SSB has by the transmission and reception point 140 been transmitted on beam 3a and that the user equipment 200 has determined the best corresponding candidate beam to be beam 3b, the network node 300 (not shown) might then when the SSB is transmitted in beam 2a from the transmission and reception point 140 provide the user equipment 200 with directional information that indicates the best likely beam directions to be confined to an area “to the right” (i . e. , corresponding to a search sector within which beams 2b and lb are confined) of the best beam for receiving the SSB transmitted in beam 3a. Similarly, when the SSB is transmitted in beam 5a from the transmission and reception point 140 the UE might be instructed to search in the area “to the left” (i.e., corresponding to a search sector within which beams 4b and 5b are confined) of the best beam for receiving the SSB transmitted in beam 3a.

Fig. 11 schematically illustrates, in terms of a number of functional units, the components of a user equipment 200 according to an embodiment. Processing circuitry 210 is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), etc., capable of executing software instructions stored in a computer program product 1510a (as in Fig. 15), e.g. in the form of a storage medium 230. The processing circuitry 210 may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA).

Particularly, the processing circuitry 210 is configured to cause the user equipment 200 to perform a set of operations, or steps, as disclosed above. For example, the storage medium 230 may store the set of operations, and the processing circuitry 210 may be configured to retrieve the set of operations from the storage medium 230 to cause the user equipment 200 to perform the set of operations. The set of operations maybe provided as a set of executable instructions. Thus the processing circuitry 210 is thereby arranged to execute methods as herein disclosed.

The storage medium 230 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory. The user equipment 200 may further comprise a communications interface 220 for communications with other entities, functions, nodes, and devices. As such the communications interface 220 may comprise one or more transmitters and receivers, comprising analogue and digital components.

The processing circuitry 210 controls the general operation of the user equipment 200 e.g. by sending data and control signals to the communications interface 220 and the storage medium 230, by receiving data and reports from the communications interface 220, and by retrieving data and instructions from the storage medium 230. Other components, as well as the related functionality, of the user equipment 200 are omitted in order not to obscure the concepts presented herein.

Fig. 12 schematically illustrates, in terms of a number of functional modules, the components of a user equipment 200 according to an embodiment. The user equipment 200 of Fig. 12 comprises a number of functional modules; an obtain module 210a configured to perform step S102, and an evaluate module 210c configured to perform step S106. The user equipment 200 of Fig. 12 may further comprise a number of optional functional modules, such as a receive module 210b configured to perform step S104. In general terms, each functional module 210a: 210c may be implemented in hardware or in software. Preferably, one or more or all functional modules 2ioa:2ioc may be implemented by the processing circuitry 210, possibly in cooperation with the communications interface 220 and/or the storage medium 230. The processing circuitry 210 may thus be arranged to from the storage medium 230 fetch instructions as provided by a functional module 2ioa:2ioc and to execute these instructions, thereby performing any steps of the user equipment 200 as disclosed herein.

Fig. 13 schematically illustrates, in terms of a number of functional units, the components of a network node 300 according to an embodiment. Processing circuitry 310 is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), etc., capable of executing software instructions stored in a computer program product 1510b (as in Fig. 15), e.g. in the form of a storage medium 330. The processing circuitry 310 may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA). Particularly, the processing circuitry 310 is configured to cause the network node 300 to perform a set of operations, or steps, as disclosed above. For example, the storage medium 330 may store the set of operations, and the processing circuitry 310 may be configured to retrieve the set of operations from the storage medium 330 to cause the network node 300 to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus the processing circuitry 310 is thereby arranged to execute methods as herein disclosed.

The storage medium 330 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory.

The network node 300 may further comprise a communications interface 320 for communications with other entities, functions, nodes, and devices. As such the communications interface 320 may comprise one or more transmitters and receivers, comprising analogue and digital components.

The processing circuitry 310 controls the general operation of the network node 300 e.g. by sending data and control signals to the communications interface 320 and the storage medium 330, by receiving data and reports from the communications interface 320, and by retrieving data and instructions from the storage medium 330. Other components, as well as the related functionality, of the network node 300 are omitted in order not to obscure the concepts presented herein.

Fig. 14 schematically illustrates, in terms of a number of functional modules, the components of a network node 300 according to an embodiment. The network node 300 of Fig. 14 comprises a number of functional modules; an estimate module 310a configured to perform step S202, a determine module 3iod configured to perform step S208, and a provide module 3iof configured to perform step S112. The network node 300 of Fig. 14 may further comprise a number of optional functional modules, such as any of an obtain module 310b configured to perform step S204, an obtain module 310c configured to perform step S206, and an instruct module 3ioe configured to perform step S110. In general terms, each functional module 3ioa:3iof may be implemented in hardware or in software. Preferably, one or more or all functional modules 3ioa:3iof may be implemented by the processing circuitry 310, possibly in cooperation with the communications interface 320 and/or the storage medium 330. The processing circuitry 310 may thus be arranged to from the storage medium 330 fetch instructions as provided by a functional module 3ioa:3iof and to execute these instructions, thereby performing any steps of the network node 300 as disclosed herein.

The network node 300 may be provided as a standalone device or as a part of at least one further device. For example, the network node 300 may be provided in a node of the radio access network or in a node of the core network. Alternatively, functionality of the network node 300 may be distributed between at least two devices, or nodes. These at least two nodes, or devices, may either be part of the same network part (such as the radio access network or the core network) or may be spread between at least two such network parts. In general terms, instructions that are required to be performed in real time may be performed in a device, or node, operatively closer to the cell than instructions that are not required to be performed in real time.

Thus, a first portion of the instructions performed by the network node 300 may be executed in a first device, and a second portion of the instructions performed by the network node 300 may be executed in a second device; the herein disclosed embodiments are not limited to any particular number of devices on which the instructions performed by the network node 300 may be executed. Hence, the methods according to the herein disclosed embodiments are suitable to be performed by a network node 300 residing in a cloud computational environment. Therefore, although a single processing circuitry 310 is illustrated in Fig. 13 the processing circuitry 310 may be distributed among a plurality of devices, or nodes. The same applies to the functional modules 3ioa:3iof of Fig. 14 and the computer program 1520b of Fig. 15.

Fig. 15 shows one example of a computer program product 1510a, 1510b comprising computer readable means 1530. On this computer readable means 1530, a computer program 1520a can be stored, which computer program 1520a can cause the processing circuitry 210 and thereto operatively coupled entities and devices, such as the communications interface 220 and the storage medium 230, to execute methods according to embodiments described herein. The computer program 1520a and/or computer program product 1510a may thus provide means for performing any steps of the user equipment 200 as herein disclosed. On this computer readable means 1530, a computer program 1520b can be stored, which computer program 1520b can cause the processing circuitry 310 and thereto operatively coupled entities and devices, such as the communications interface 320 and the storage medium 330, to execute methods according to embodiments described herein. The computer program 1520b and/or computer program product 1510b may thus provide means for performing any steps of the network node 300 as herein disclosed.

In the example of Fig. 15, the computer program product 1510a, 1510b is illustrated as an optical disc, such as a CD (compact disc) or a DVD (digital versatile disc) or a Blu- Ray disc. The computer program product 1510a, 1510b could also be embodied as a memory, such as a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), or an electrically erasable programmable read-only memory (EEPROM) and more particularly as a non-volatile storage medium of a device in an external memory such as a USB (Universal Serial Bus) memory or a Flash memory, such as a compact Flash memory. Thus, while the computer program 1520a, 1520b is here schematically shown as a track on the depicted optical disk, the computer program 1520a, 1520b can be stored in any way which is suitable for the computer program product 1510a, 1510b.

The inventive concept has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the inventive concept, as defined by the appended patent claims.

Claims

22 CLAIMS

1. A method for performing a beam finding procedure with a network node (300), the method being performed by a user equipment (200), the method comprising: obtaining (S102) directional information indicating beam directions in which the beam finding procedure is to be performed, wherein the beam directions define a search sector (190); and evaluating (S106), as part of performing the beam finding procedure, a set of candidate beams (170) by performing a beam scan, wherein the candidate beams (170) that are inside the search sector (190) are scanned more frequently than the candidate beams (170) that are outside the search sector (190).

2. The method according to claim 1, wherein the candidate beams (170) that are inside the search sector (190) are scanned more frequently in time than the candidate beams (170) that are outside the search sector (190).

3. The method according to claim 1 or 2, wherein a higher density of the candidate beams (170) is used when performing the beam scan inside the search sector (190) than when performing the beam scan outside the search sector (190).

4. The method according to any preceding claim, wherein the directional information is obtained from the network node (300).

5. The method according to any preceding claim, wherein the directional information is obtained as system information, as radio resource control, RRC, information, as medium access control, MAC, information, as downlink control information, DCI, as handover information, or as random access channel information.

6. The method according to any preceding claim, wherein the directional information is provided as any of: bearing, elevation, sector range.

7. The method according to any preceding claim, wherein the directional information specifies a vertical height of a transmission and reception point (140) of the network node (300).

8. The method according to any preceding claim, wherein the directional information is specified as a compass direction.

9. The method according to any preceding claim, wherein the user equipment (200) has an established directive wireless link to a transmission and reception point (140) of the network node (300), and wherein the directional information is specified in relation to a direction of the directive wireless link.

10. The method according to any preceding claim, wherein the method further comprises: receiving (S104) instructions from the network node (300) to scan the candidate beams (170) that are inside the search sector (190) are more frequently than the candidate beams (170) that are outside the search sector (190).

11. The method according to any preceding claim, wherein each of the candidate beams (170) is used for receiving and measuring on reference signals received from the network node (300), and wherein the reference signals are synchronization signal block, SSB, signals.

12. A method for assisting a user equipment (200) to perform a beam finding procedure, the method being performed by a network node (300), the method comprising: estimating (S202) direction towards the user equipment (200) with respect to a transmission and reception point (140) of the network node (300); determining (S208) beam directions in which the beam finding procedure is to be performed, wherein the beam directions define a search sector (190) and are a function of the estimated direction towards the user equipment (200); and providing (S212) the directional information towards the user equipment (200).

13. The method according to claim 12, wherein the direction towards the user equipment (200) is estimated from direction-of-arrival estimates of transmissions from the user equipment (200) towards the transmission and reception point (140).

14. The method according to claim 12 or 13, wherein the method further comprises: obtaining (S204) information of location of the user equipment (200), and wherein the beam directions further are determined as a function of the location of the user equipment (200).

15. The method according to any of claims 12 to 14, wherein the method further comprises: obtaining (S206) information of locations of transmission and reception points of other network nodes, and wherein the beam directions further are determined as a function of the locations of the transmission and reception points of the other network nodes.

16. The method according to any of claims 12 to 15, wherein the beam directions further are a function of network deployment information, historically made radio measurements, or modelled network performance.

17. The method according to any of claims 12 to 16, wherein the directional information is provided as system information, as radio resource control, RRC, information, as medium access control, MAC, information, as downlink control information, DCI, as handover information, or as random access channel information.

18. The method according to any of claims 12 to 17, wherein the directional information is provided as any of: bearing, elevation, sector range.

19. The method according to any of claims 12 to 18, wherein the directional information specifies a vertical height of a transmission and reception point (140) of the network node (300).

20. The method according to any of claims 12 to 19, wherein the directional information is specified as a compass direction.

21. The method according to any of claims 12 to 20, wherein the user equipment (200) has an established directive wireless link to the transmission and reception point (140) of the network node (300), and wherein the directional information is specified in relation to a direction of the directive wireless link. 25

22. The method according to any of claims 12 to 21, wherein the user equipment (200), as part of performing the beam finding procedure, evaluates a set of candidate beams (170) by performing a beam scan, and wherein the method further comprises: instructing (S210) the user equipment (200) to scan the candidate beams (170) that are inside the search sector (190) more frequently than the candidate beams (170) that are outside the search sector (190).

23. The method according to claim 22, wherein the user equipment (200) is instructed to scan the candidate beams (170) that are inside the search sector (190) more frequently in time than the candidate beams (170) that are outside the search sector (190).

24. The method according to claim 22, wherein the user equipment (200) is instructed to use a higher density of the candidate beams (170) when performing the beam scan inside the search sector (190) than when performing the beam scan outside the search sector (190).

25. A user equipment (200) for performing a beam finding procedure with a network node (300), the user equipment (200) comprising processing circuitry (210), the processing circuitry being configured to cause the user equipment (200) to: obtain directional information indicating beam directions in which the beam finding procedure is to be performed, wherein the beam directions define a search sector (190); and evaluate, as part of performing the beam finding procedure, a set of candidate beams (170) by performing a beam scan, wherein the candidate beams (170) that are inside the search sector (190) are scanned more frequently than the candidate beams (170) that are outside the search sector (190).

26. A user equipment (200) for performing a beam finding procedure with a network node (300), the user equipment (200) comprising: an obtain module (210a) configured to obtain directional information indicating beam directions in which the beam finding procedure is to be performed, wherein the beam directions define a search sector (190); and 26 an evaluate module (210c) configured to evaluate, as part of performing the beam finding procedure, a set of candidate beams (170) by performing a beam scan, wherein the candidate beams (170) that are inside the search sector (190) are scanned more frequently than the candidate beams (170) that are outside the search sector (190).

27. The user equipment (200) according to claim 25 or 26, further being configured to perform the method according to any of claims 2 to 11.

28. A network node (300) for assisting a user equipment (200) to perform a beam finding procedure, the network node (300) comprising processing circuitry (310), the processing circuitry being configured to cause the network node (300) to: estimate direction towards the user equipment (200) with respect to a transmission and reception point (140) of the network node (300); determine beam directions in which the beam finding procedure is to be performed, wherein the beam directions define a search sector (190) and are a function of the estimated direction towards the user equipment (200); and provide the directional information towards the user equipment (200).

29. A network node (300) for assisting a user equipment (200) to perform a beam finding procedure, the network node (300) comprising: an estimate module (310a) configured to estimate direction towards the user equipment (200) with respect to a transmission and reception point (140) of the network node (300); a determine module (3iod) configured to determine beam directions in which the beam finding procedure is to be performed, wherein the beam directions define a search sector (190) and are a function of the estimated direction towards the user equipment (200); and a provide module (3iof) configured to provide the directional information towards the user equipment (200). 27

30. The network node (300) according to 28 or 29, further being configured to perform the method according to any of claims 13 to 24.

31. A computer program (1520a) for performing a beam finding procedure with a network node (300), the computer program comprising computer code which, when run on processing circuitry (210) of a user equipment (200), causes the user equipment (200) to: obtain (S102) directional information indicating beam directions in which the beam finding procedure is to be performed, wherein the beam directions define a search sector (190); and evaluate (S106), as part of performing the beam finding procedure, a set of candidate beams (170) by performing a beam scan, wherein the candidate beams (170) that are inside the search sector (190) are scanned more frequently than the candidate beams (170) that are outside the search sector (190).

32. A computer program (1520b) for assisting a user equipment (200) to perform a beam finding procedure, the computer program comprising computer code which, when run on processing circuitry (310) of a network node (300), causes the network node (300) to: estimate (S202) direction towards the user equipment (200) with respect to a transmission and reception point (140) of the network node (300); determine (S208) beam directions in which the beam finding procedure is to be performed, wherein the beam directions define a search sector (190) and are a function of the estimated direction towards the user equipment (200); and provide (S212) the directional information towards the user equipment (200).

33. A computer program product (1510a, 1510b) comprising a computer program (1520a, 1520b) according to at least one of claims 31 and 32, and a computer readable storage medium (1530) on which the computer program is stored.