WO2017140374A1

WO2017140374A1 - Terminal device mobility-based beam switching

Info

Publication number: WO2017140374A1
Application number: PCT/EP2016/053512
Authority: WO
Inventors: Maxim TESLENKO; Hongxin LIANG; Konstantinos Vandikas; Sibel TOMBAZ
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2016-02-19
Filing date: 2016-02-19
Publication date: 2017-08-24

Abstract

The present disclosure provides a method in a network node for facilitating beam switching, and related network node. The method comprises determining, for a terminal device moving along a route, one or more switching locations at which beam switching is to be performed for the terminal device and respective target beams to which the terminal device is to be switched at the switching locations. When the terminal device is about to arrive at one of the switching locations, a beam switching indication including said one of the switching locations and a respective one of the target beams is sent to a serving access node of the terminal device, so that the terminal device is switched to said respective one of the target beams at said one of the switching locations. The present disclosure also provides a method in an access node for performing beam switching and related access node.

Description

TERMINAL DEVICE MOBILITY-BASED BEAM SWITCHING

TECHNICAL FIELD

The present disclosure generally relates to the field of wireless communications, and particularly, to a method in a network node for facilitating beam switching and related network node and a method in an access node for performing beam switching and related access node.

BACKGROUND This section is intended to provide a background to the various embodiments of the technology described in this disclosure. The description in this section may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and/or claims of this disclosure and is not admitted to be prior art by the mere inclusion in this section.

In existing Long Term Evolution (LTE) wireless communications systems, a beam tracking process for a User Equipment (UE) requires a continuous mobility

measurement process which constantly evaluates data transmission quality at both the UE and its serving access node, in order to decide whether beam switching is needed at a position and if needed which beam the UE is to be switched to. Unless otherwise specified, the term "beam switching" is used herein to generically refer to switching of a UE between different beams from its current serving access node (as shown in Fig. 1 (a)) or from a beam from its current serving access node to a beam from a target access node (as shown in Fig. 1 (b)). The term "access node switching" is used to specifically refer to switching of the UE from a beam from its current serving access node to a beam from a target access node (as shown in Fig. 1 (b)).

More specifically, the beam tracking process starts with the UE that is connected to its serving node. By way of example, the UE is a connected device with a Subscriber Identity Module (SIM) card and can be mounted on a vehicle, such as a bus, which moves along a predefined route, and the UE's serving node is a base station. Based on the quality of the ongoing transmission, the serving node triggers mobility measurements. The quality can be determined by Down-link Mobility Reference Signals Signal to Interference Plus Noise Ratio (DL-MRS SINR) as reported by the UE, averaged over time.

At the serving node, a DL-MRS activation table is stored which contains achievable or acceptable link quality values for all geographical UE positions within the area potentially served by the node. These link quality values are collected over time, based on observed link performance and the reported DL-MRS measurements. The DL-MRS activation table also provides a mapping between the UE position and relevant candidate beams (and optionally their reference signal quality values at the UE position).

Based on the UE position and the DL-MRS activation table, a selection process is performed at the serving node, so that not only candidate beams from the current serving node but also from other access nodes are selected. All information on the selected access nodes is sent to the UE which uses that information in order to generate a UE measurement report. The UE measurement report is then sent to the serving node which based on the measurement report may or may not trigger beam switching inside the serving node or access node switching.

The beam tracking process described above can become computationally expensive, when it comes to constantly measuring the data transmission quality and deciding based on the measurements where beam switching shall be performed and which beam the UE shall be switched to. This may result in an increase in the amount of energy consumed both on the UE and the serving node. Also it increases the amount of signaling that is exchanged over the network. SUMMARY

An object of the present disclosure is to overcome or at least alleviate some of the above-described disadvantages.

According to a first aspect of the present disclosure, there is provided a method in a network node for facilitating beam switching. The method comprises determining, for a terminal device moving along a route, one or more switching locations at which beam switching is to be performed for the terminal device and respective target beams to which the terminal device is to be switched at the switching locations. The method further comprises, when the terminal device is about to arrive at one of the switching locations, sending, to a serving access node of the terminal device, a beam switching indication including said one of the switching locations and a respective one of the target beams so that the terminal device is switched to said respective one of the target beams at said one of the switching locations.

According to a second aspect of the present disclosure, there is provided a method in an access node for performing beam switching. The method comprises receiving, from a network node, a beam switching indication including a switching location where beam switching of a terminal device is to be performed and a target beam to which the terminal device is to be switched at the switching location. The method further comprises performing beam switching according to the beam switching indication. According to a third aspect of the present disclosure, there is provided a network node for facilitating beam switching. The network node comprises a determining unit and a transmitting unit. The determining unit is configured to determine, for a terminal device moving along a route, one or more switching locations at which beam switching is to be performed for the terminal device and respective target beams to which the terminal device is to be switched at the switching locations. The transmitting unit is configured to send, to a serving access node of the terminal device, a beam switching indication including one of the switching locations and a respective one of the target beams so that the terminal device is switched to said respective one of the target beams at said one of the switching locations, when the terminal device is about to arrive at said one of the switching locations.

According to a fourth aspect of the present disclosure, there is provided an access node for performing beam switching. The access node comprises a receiving unit and a beam switching unit. The receiving unit is configured to receive, from a network node, a beam switching indication including a switching location where beam switching of a terminal device moving along a route is to be performed and a target beam to which the terminal device is to be switched at the switching location. The beam switching unit is configured to perform beam switching according to the beam switching indication.

According to a fifth aspect of the present disclosure, there is provided a computer program that comprises instructions which, when executed by a processor, cause an apparatus to perform the actions of the first or the second aspect.

By arranging a network node that determines one or more switching locations at which beam switching is to be performed for a terminal device moving along a route and respective target beams to which the terminal device is to be switched at the switching locations and sends to a serving access node of the terminal device a beam switching indication including one of the switching locations and a respective one of the target beams when the terminal device is about to arrive at said one of the switching locations, the mobility of the terminal device is taken into account to facilitate the beam switching process. As a result, it is no longer needed to constantly measure data transmission quality at both the terminal device and the serving access node and to determine based on the measurements where beam switching shall be performed and which beam the terminal device shall be switched to. Accordingly, electrical power and wireless communication resources at both the terminal device and the access node can be saved.

As those skilled in the art would appreciate, the present disclosure is applicable to not only LTE systems but also other wireless communication systems. Therefore, the term "terminal device" is used herein to broadly refer to a terminal communication device in any kind of wireless communication systems. In LTE systems, a terminal device specifically refers to a UE.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features, and advantages of the present disclosure will become apparent from the following descriptions on embodiments of the present disclosure with reference to the drawings, in which:

Fig. 1 is a diagram illustrating two cases of beam switching; Fig. 2 is sequence diagram illustrating a learning phase of a terminal device mobility-based beam switching process according to the present disclosure;

Fig. 3 is sequence diagram illustrating a beam switching phase of a terminal device mobility-based beam switching process according to an embodiment of the present disclosure; Fig. 4 is a sequence diagram illustrating a beam switching phase of a terminal device mobility-based beam switching process according to another embodiment of the present disclosure;

Figs. 5-9 are flowcharts illustrating operations of a method in a network node for facilitating beam switching according to the present disclosure; Fig. 10 is a flowchart illustrating a method in an access node for performing beam switching according to the present disclosure;

Fig. 1 1 is a schematic diagram illustrating a structure of a network node for facilitating beam switching according to the present disclosure; and

Fig. 12 is a schematic diagram illustrating a structure of an access node for performing beam switching according to the present disclosure.

Fig. 13 shows an example of an apparatus for performing operations of a method according to embodiments of the present disclosure.

DETAILED DESCRIPTION

In the discussion that follows, specific details of particular embodiments of the present techniques are set forth for purposes of explanation and not limitation. It will be appreciated by those skilled in the art that other embodiments may be employed apart from these specific details. Furthermore, in some instances detailed descriptions of well-known methods, nodes, interfaces, circuits, and devices are omitted so as not obscure the description with unnecessary detail. Those skilled in the art will appreciate that the functions described may be

implemented in one or in several nodes. Some or all of the functions described may be implemented using hardware circuitry, such as analog and/or discrete logic gates interconnected to perform a specialized function, application specific integrated circuits (ASICs), programmable logical arrays (PLAs), etc. Likewise, some or all of the functions may be implemented using software programs and data in conjunction with one or more digital microprocessors or general purpose computers. Where nodes that communicate using the air interface are described, it will be appreciated that those nodes also have suitable radio communications circuitry. Moreover, the technology can additionally be considered to be embodied entirely within any form of

computer-readable memory, including non-transitory embodiments such as

solid-state memory, magnetic disk, or optical disk containing an appropriate set of computer instructions that would cause a processor to carry out the techniques described herein.

Hardware implementations of the presently disclosed techniques may include or encompass, without limitation, digital signal processor (DSP) hardware, a reduced instruction set processor, hardware (e.g., digital or analog) circuitry including but not limited to ASIC(s) and/or field programmable gate array(s) (FPGA(s)), and (where appropriate) state machines capable of performing such functions. In terms of computer implementation, a computer is generally understood to comprise one or more processors or one or more controllers, and the terms computer, processor, and controller may be employed interchangeably. When provided by a computer, processor, or controller, the functions may be provided by a single dedicated computer or processor or controller, by a single shared computer or processor or controller, or by a plurality of individual computers or processors or controllers, some of which may be shared or distributed. Moreover, the term

"processor" or "controller" also refers to other hardware capable of performing such functions and/or executing software, such as the example hardware recited above. To overcome or at least alleviate some of the disadvantages of the beam tracking process described above, the present application proposes introducing a network node that determines one or more switching locations at which beam switching is to be performed for a terminal device moving along a route and respective target beams to which the terminal device is to be switched at the switching locations and sends to a serving access node of the terminal device a beam switching indication including one of the switching locations and a respective one of the target beams when the terminal device is about to arrive at said one of the switching locations. As such, the mobility of the terminal device is taken into account when performing the beam switching process, and because the mobility and the beaming switching pattern of the terminal device are already known to the terminal device and the serving access node it is no longer needed to constantly measure data transmission quality at both the terminal device and the serving access node and to determine based on the measurements where beam switching shall be performed and which beam the terminal device shall be switched to. Accordingly, electrical power and wireless communication resources at both the terminal device and the access node can be saved.

In an embodiment, in order for the network node to determine the switching locations and the respective target beams for the terminal device, a learning phase may be undergone in advance. During the learning phase, the network node recorded one or more switching locations at which beam switching was performed for the same terminal device or a different terminal device which moved along the route and respective target beams to which the same or the different terminal device was switched at the switching locations. Accordingly, the network node can determine the switching locations for the terminal device as the switching locations recorded during the learning phase for the same or the different terminal device and determine the respective target beams for the terminal device as the respective target beams recorded during the learning phase for the same or the different terminal device.

Thus, by undergoing the learning phase only once for a terminal device which moves along a route, the switching locations and respective target beams for the same terminal device moving along the route once again or a different terminal device moving along the route can be directly determined as the switching locations and respective target beams recorded during the learning phase.

In practical implementation, the learning phase can be carried out a little more times to improve the preciseness of learned knowledge about the switching locations and respective target beams.

To facilitate understanding of the learning phase, reference can be made to Fig. 2. As illustrated, at step s210, a terminal device reports MRS measurements to its serving access node. Then, the serving access node decides that beam switching shall be performed for the terminal device based on the reported MRS measurements at step s220.

In case the beam switching is switching of the terminal device between different beams from its current serving access node as mentioned in the background section and as illustrated in Fig. 1 (a), after it makes the beam switching decision at step s220, the serving access node sends the switching location and the target beam to a network node at step s250. At step s260, the network node records the switching location and the target beam.

In case the beam switching is switching of the terminal device from a beam from its current serving access node to a beam from a target access node, i.e., access node switching as mentioned in the background section and as illustrated in Fig. 1 (b), after making the beam switching decision at step s220 and before sending the switching location and the target beam to the network node at step s250, the serving access node further sends a beam switching request to the target access node at step s230 and receives a beam switching acknowledgement from the target access node at step s240 as illustrated in Fig. 2 by dashed arrows.

In practical implementation, a switching location may be represented for example as latitude and longitude, and may be determined at the serving access node as a geographical location of the terminal device reported by the terminal device together with the MRS measurements corresponding to the geographical location when the serving access node decides that beam switching shall be performed for the terminal device based on the MRS measurements corresponding to the location.

In order for the terminal device to report its geographical location, the terminal device is provided with some kind of positioning mechanism, such as Global Positioning System (GPS), Advanced Forward Link Trilateration (AFLT), etc.

As an alternative embodiment, instead of undergoing the learning phase, the network node may derive, for the terminal device, one or more switching locations where beam switching is to be performed and respective target beams to which the terminal device is to be switched at the switching locations, from the route, a radio propagation model and a deployment of access nodes. Accordingly, the network node can determine the switching locations and respective target beams for the terminal device as the derived switching locations and the derived respective target beams.

Without having to constantly measure data transmission quality at both the terminal device and the serving access node and to determine based on the measurements where beam switching shall be performed and which beam the terminal device shall be switched to, beam switching for the terminal device is performed simply based on the mobility of the terminal device and the switching locations and respective target beams determined by the network node for the terminal device as described in detail in the above embodiments.

To facilitate better understanding of such terminal device mobility-based beam switching, reference will be made to Figs. 3 and 4 which depict an embodiment where the beam switching is triggered by the terminal device and an embodiment where the beam switching is triggered by the network node respectively.

As illustrated in Fig. 3, at step s310, a terminal device sends a notification to its serving access node, notifying that it enters a neighborhood of one of the switching locations stored in the network node. To this end, the terminal device is not only provided with some kind of positioning mechanism but it also prestores the switching locations determined by a network node for the terminal device as described above.

After receiving the notification from the terminal device, the serving access node sends a request for a beam switching indication to the network node at step s320. In response, the network node sends the beam switching indication including said one of the switching locations and a respective one of the target beams at step s330.

In case the beam switching is switching of the terminal device from a beam from its current serving access node to a beam from a target access node (i.e., access node switching as mentioned in the background section and as illustrated in Fig. 1 (b)), after receiving the beam switching indication from the network node at step s330, the serving access node further sends a beam switching request to the target access node at step s340 and receives a beam switching acknowledgement from the target access node at step s350 as illustrated in Fig. 3 by dashed arrows.

Alternatively, as illustrated in Fig. 4, a terminal device periodically sends its

geographical location to its serving access node at step s410, and the serving access node forwards at step s420 the received geographical location to a network node, at which the switching locations and respective target beams for the terminal device are determined as described above. Then, the network node predicts at step s430 that the terminal device is about to arrive at one of the switching locations based on the current location of the terminal device received from the serving access node and possibly estimated velocity and moving direction of the terminal device, and sends to the serving access node a beam switching indication including said one of the switching locations and a respective one of the target beams at step s440.

In case the beam switching is switching of the terminal device from a beam from its current serving access node to a beam from a target access node (i.e., access node switching as mentioned in the background section and as illustrated in Fig. 1 (b)), after receiving the beam switching indication from the network node at step s440, the serving access node further sends a beam switching request to the target access node at step s450 and receives a beam switching acknowledgement from the target access node at step s460 as illustrated in Fig. 4 by dashed arrows.

In a scenario where the terminal device sticks to a moving schedule, the network node may predict that the terminal device is about to arrive at one of the switching locations directly based on the moving schedule. Accordingly, there is no need for the terminal device to report its geographical location periodically.

As would be appreciated by those skilled in the art, the proposed terminal device mobility-based beam switching process is particularly useful for cases where a terminal device moves along a predefined route regularly and where a group of terminal devices move along the same route. In the former case, the terminal device may be mounted on a private car of a person who commutes by car. In the latter case, the group of terminal devices may be mounted on a team of buses or trucks respectively. It should also be noted that a hybrid implementation is feasible and practicable, wherein the switching locations and respective target beams are determined not only by performing the above-described terminal device mobility-based beam switching process but also based on periodic channel quality measurements which are performed at a reduced frequency compared with the conventional beam tracking process. In this way, signaling exchange and power consumption are reduced while allowing for agility to adapt to the ever-changing wireless environment.

In the following, operations of a method 500 in a network node for facilitating beam switching will be described with reference to Figs. 5-9. As those skilled in the art would appreciate, the operations of the method 500 include some or all of the

above-described operations performed at the network node.

As illustrated in Fig. 5, the method 500 comprises steps s510 and s530. At step s510, for a terminal device moving along a route, one or more switching locations at which beam switching is to be performed for the terminal device and respective target beams to which the terminal device is to be switched at the switching locations are determined.

At step s530, when the terminal device is about to arrive at one of the switching locations, a beam switching indication including said one of the switching locations and a respective one of the target beams is sent to a serving access node of the terminal device, so that the terminal device is switched to said respective one of the target beams at said one of the switching locations.

In an embodiment, step s510 may further comprise steps s511 and s512 as illustrated in Fig. 6. At step s511 , one or more switching locations at which beam switching was performed for the same terminal device or a different terminal device which moved along the route and respective target beams to which the same or the different terminal device was switched at the switching locations are recorded.

At step s512, the switching locations for the terminal device are determined as the switching locations recorded for the same or the different terminal device, and the respective target beams for the terminal device are determined as the respective target beams recorded for the same or the different terminal device.

In an alternative embodiment, step s510 may further comprise steps s511 ' and s512' as illustrated in Fig. 7. At step s511 ', for the terminal device, one or more switching locations where beam switching is to be performed and respective target beams to which the terminal device is to be switched at the switching locations are derived from the route, a radio propagation model and a deployment of access nodes At step s512', the switching locations and the respective target beams for the terminal device are determined as the derived switching locations and the derived respective target beams.

In an embodiment, the method 500 may further comprise step s520 as illustrated in Fig. 8. At step s520, a request for the beam switching indication is received from the serving access node, which request is sent by the serving access node upon receiving from the terminal device a notification that the terminal device enters a neighborhood of said one of the switching locations. In this embodiment, the beam switching indication is sent by the network node to the serving access node upon receipt of the request for the beam switching indication. In an alternative embodiment, the method 500 may further comprise step s520' as illustrated in Fig. 9. At step s520', it is predicted that the terminal device is about to arrive at said one of the switching locations, based on a current location of the terminal device received periodically from the serving access node or on a moving schedule of the terminal device. In this embodiment, the beam switching indication is sent by the network node to the serving access node upon predicting that the terminal device is about to enter a neighborhood of said one of the switching locations.

In an embodiment, the terminal device may be mounted on a vehicle.

Fig. 10 depicts operations of a method 1000 in an access node for performing beam switching. As those skilled in the art would appreciate, the operations of the method 1000 include some or all of the above-described operations performed at the serving access node.

As illustrated, the method 1000 comprises steps s1020 and s1030. At step s1020, a beam switching indication including a switching location where beam switching of a terminal device is to be performed and a target beam to which the terminal device is to be switched at the switching location is received from a network node. At step s1030, beam switching is performed according to the beam switching indication. In an embodiment, the method 1000 may further comprise step s1010. At step s1010, when beam switching was performed for the same terminal device or a different terminal device moving along the route at the switching location to the target beam, the switching location and the target beam are sent to the network node, where the switching location and the target beam are recorded so that, when the same or the different terminal device is about to arrive at the switching location, the beam switching indication is sent from the network node to the access node.

In the following, structures of a network node 1 100 for facilitating beam switching and an access node 1200 for performing beam switching according to the present disclosure will be described with reference to Figs. 1 1 and 12 respectively. As illustrated in Fig. 1 1 , the network node 1 100 comprises a determining unit 1110 and a transmitting unit 1130. The determining unit 1110 is configured to determine, for a terminal device moving along a route, one or more switching locations at which beam switching is to be performed for the terminal device and respective target beams to which the terminal device is to be switched at the switching locations. The transmitting unit 1130 is configured to send, to a serving access node of the terminal device, a beam switching indication including one of the switching locations and a respective one of the target beams so that the terminal device is switched to said respective one of the target beams at said one of the switching locations, when the terminal device is about to arrive at said one of the switching locations. In an embodiment, the determining unit 1 1 10 may comprise a recording subunit 1111 and a determining subunit 1112. The recoding subunit 1111 may be configured to record one or more switching locations at which beam switching was performed for the same terminal device or a different terminal device which moved along the route and respective target beams to which the same or the different terminal device was switched at the switching locations. The determining subunit 1112 may be configured to determine the switching locations for the terminal device as the switching locations recorded for the same or the different terminal device and to determine the respective target beams for the terminal device as the respective target beams recorded for the same or the different terminal device.

In an alternative embodiment, the determining unit 1110 may comprise a deriving subunit 1111 ' and a determining subunit 1112'. The deriving subunit 1111 ' may be configured to derive, for the terminal device, one or more switching locations where beam switching is to be performed and respective target beams to which the terminal device is to be switched at the switching locations, from the route, a radio propagation model and a deployment of access nodes. The determining subunit 1112' may be configured to determine the switching locations and the respective target beams for the terminal device as the derived switching locations and the derived respective target beams.

In an embodiment, the network node 1100 may further comprise a receiving unit 1120. The receiving unit 1120 may be configured to receive, from the serving access node, a request for the beam switching indication, which request is sent by the serving access node upon receiving from the terminal device a notification that the terminal device enters a neighborhood of said one of the switching locations. The beam switching indication is sent by the network node to the serving access node upon receipt of the request for the indication.

In an alternative embodiment, the network node 1100 may further comprise a predicting unit 1120'. The predicting unit 1120' may be configured to predict that the terminal device is about to arrive at said one of the switching locations, based on a current location of the terminal device received periodically from the serving access node or on a moving schedule of the terminal device. The beam switching indication is sent by the network node to the serving access node upon predicting that the terminal device is about to enter a neighborhood of said one of the switching locations. As illustrated in Fig. 12, the access node 1200 comprises a receiving unit 1220 and a beam switching unit 1230. The receiving unit 1220 is configured to receive, from a network node, a beam switching indication including a switching location where beam switching of a terminal device moving along a route is to be performed and a target beam to which the terminal device is to be switched at the switching location. The beam switching unit 1230 is configured to perform beam switching according to the beam switching indication.

In an embodiment, the access node 1200 may further comprise a transmitting unit 1210. The transmitting unit 1210 is configured to, when beam switching was performed for the same terminal device or a different terminal device moving along the route at the switching location to the target beam, send the switching location and the target beam to the network node, where the switching location and the target beam are recorded so that, when the same or the different terminal device is about to arrive at the switching location, the beam switching indication is sent from the network node to the access node.

Figure 13 shows an example of an apparatus 1300 performing the method 500 illustrated in Figures 5 to 9. The apparatus comprises an input 1301 for receiving a request for a beam switching indication and/or geographical location of switching locations and target beams, and an output 1303 for sending a beam switching indication. The apparatus 1300 further comprises a processor 1305, e.g. a central processing unit (CPU), and a computer program product 1307 in the form of a memory for storing the instructions, e.g. computer program 1309 that, when retrieved from the memory and executed by the processor 1305 causes the apparatus 1300 to perform processes connected with embodiments of the present beam switching. The processor 1305 is communicatively coupled to the input node 1301 , to the output node 1303 and to the memory 1307.

Alternatively, an apparatus 1300 performs the method 1000 illustrated in Figure 10. The apparatus comprises an input 1301 for receiving a beam switching indication, and an output 1303 for sending the switching location and the target beam or a beam switching request. The apparatus 1300 further comprises a processor 1305, e.g. a central processing unit (CPU), and a computer program product 1307 in the form of a memory for storing the instructions, e.g. computer program 1309 that, when retrieved from the memory and executed by the processor 1305 causes the apparatus 1300 to perform processes connected with embodiments of the present beam switching.

The present disclosure is described above with reference to the embodiments thereof. However, those embodiments are provided just for illustrative purpose, rather than limiting the present disclosure. The scope of the disclosure is defined by the attached claims as well as equivalents thereof. Those skilled in the art can make various alternations and modifications without departing from the scope of the disclosure, which all fall into the scope of the disclosure.

Claims

WHAT IS CLAMED IS:

1 . A method (500) in a network node for facilitating beam switching, comprising:

determining (s510), for a terminal device moving along a route, one or more switching locations at which beam switching is to be performed for the terminal device and respective target beams to which the terminal device is to be switched at the switching locations;

when the terminal device is about to arrive at one of the switching locations, sending (s530), to a serving access node of the terminal device, a beam switching indication including said one of the switching locations and a respective one of the target beams so that the terminal device is switched to said respective one of the target beams at said one of the switching locations.

2. The method (500) of claim 1 , wherein the step of determining (s510) comprises: recording (s511 ) one or more switching locations at which beam switching was performed for the same terminal device or a different terminal device which moved along the route and respective target beams to which the same or the different terminal device was switched at the switching locations; and

determining (s512) the switching locations for the terminal device as the switching locations recorded for the same or the different terminal device and determining the respective target beams for the terminal device as the respective target beams recorded for the same or the different terminal device.

3. The method (500) of claim 1 , wherein the step of determining (s510) comprises: deriving (s511 '), for the terminal device, one or more switching locations where beam switching is to be performed and respective target beams to which the terminal device is to be switched at the switching locations, from the route, a radio propagation model and a deployment of access nodes; and

determining (s512') the switching locations and the respective target beams for the ternninal device as the derived switching locations and the derived respective target beams.

4. The method (500) of any of claims 1 -3, further comprising:

receiving (s520), from the serving access node, a request for the beam switching indication, which request is sent by the serving access node upon receiving from the terminal device a notification that the terminal device enters a neighborhood of said one of the switching locations,

wherein the beam switching indication is sent by the network node to the serving access node upon receipt of the request for the beam switching indication.

5. The method (500) of any of claims 1 -3, further comprising:

predicting (s520') that the terminal device is about to arrive at said one of the switching locations, based on a current location of the terminal device received periodically from the serving access node or on a moving schedule of the terminal device,

wherein the beam switching indication is sent by the network node to the serving access node upon predicting that the terminal device is about to enter a neighborhood of said one of the switching locations.

6. The method (500) of any of the preceding claims, wherein the terminal device is mounted on a vehicle.

7. A method (1000) in an access node for performing beam switching, comprising: receiving (s1020), from a network node, a beam switching indication including a switching location where beam switching of a terminal device is to be performed and a target beam to which the terminal device is to be switched at the switching location; and performing (s1030) beam switching according to the beam switching indication.

8. The method (1000) of claim 7, further comprising:

when beam switching was performed for the same terminal device or a different terminal device moving along the route at the switching location to the target beam, sending (s1010) the switching location and the target beam to the network node, where the switching location and the target beam are recorded so that, when the same or the different terminal device is about to arrive at the switching location, the beam switching indication is sent from the network node to the access node.

9. A network node (1100) for facilitating beam switching, comprising:

a determining unit (1110) configured to determine, for a terminal device moving along a route, one or more switching locations at which beam switching is to be performed for the terminal device and respective target beams to which the terminal device is to be switched at the switching locations;

a transmitting unit (1130) configured to send, to a serving access node of the terminal device, a beam switching indication including one of the switching locations and a respective one of the target beams so that the terminal device is switched to said respective one of the target beams at said one of the switching locations, when the terminal device is about to arrive at said one of the switching locations.

10. The network node (1100) of claim 9, wherein the determining unit (1110) comprises:

a recording subunit (1111 ) configured to record one or more switching locations at which beam switching was performed for the same terminal device or a different terminal device which moved along the route and respective target beams to which the same or the different terminal device was switched at the switching locations; and a determining subunit (1112) configured to determine the switching locations for the terminal device as the switching locations recorded for the same or the different terminal device and to determine the respective target beams for the terminal device as the respective target beams recorded for the same or the different terminal device.

11 . The network node (1100) of claim 9, wherein the determining unit (1110) comprises:

a deriving subunit (1111 ') configured to derive, for the terminal device, one or more switching locations where beam switching is to be performed and respective target beams to which the terminal device is to be switched at the switching locations, from the route, a radio propagation model and a deployment of access nodes; and a determining subunit (1112') configured to determine the switching locations and the respective target beams for the terminal device as the derived switching locations and the derived respective target beams.

12. The network node (1100) of any of claims 9-11 , further comprising:

a receiving unit (1120) configured to receive, from the serving access node, a request for the beam switching indication, which request is sent by the serving access node upon receiving from the terminal device a notification that the terminal device enters a neighborhood of said one of the switching locations,

wherein the beam switching indication is sent by the network node to the serving access node upon receipt of the request for the indication.

13. The network node (1100) of any of claims 9-11 , further comprising:

a predicting unit (1120') configured to predict that the terminal device is about to arrive at said one of the switching locations, based on a current location of the terminal device received periodically from the serving access node or on a moving schedule of the terminal device,

14. The network node (1100) of any of claims 9-13, wherein the terminal device is mounted on a vehicle.

15. An access node (1200) for performing beam switching, comprising:

a receiving unit (1220) configured to receive, from a network node, a beam switching indication including a switching location where beam switching of a terminal device moving along a route is to be performed and a target beam to which the terminal device is to be switched at the switching location; and

a beam switching unit (1230) configured to perform beam switching according to the beam switching indication.

16. The access node (1200) of claim 15, further comprising:

a transmitting unit (1210) configured to, when beam switching was performed for the same terminal device or a different terminal device moving along the route at the switching location to the target beam, send the switching location and the target beam to the network node, where the switching location and the target beam are recorded so that, when the same or the different terminal device is about to arrive at the switching location, the beam switching indication is sent from the network node to the access node.

17. An apparatus (1300) comprising:

a processor (1305), and a memory (1307) storing instructions (1309) that, when executed by the processor (1305), cause the apparatus to:

determine, for a terminal device moving along a route, one or more switching locations at which beam switching is to be performed for the terminal device and respective target beams to which the terminal device is to be switched at the switching locations;

when the terminal device is about to arrive at one of the switching locations, send to a serving access node of the terminal device, a beam switching indication including said one of the switching locations and a respective one of the target beams so that the terminal device is switched to said respective one of the target beams at said one of the switching locations.

18. An apparatus (1300) comprising:

receive, from a network node, a beam switching indication including a switching location where beam switching of a terminal device is to be performed and a target beam to which the terminal device is to be switched at the switching location; and perform beam switching according to the beam switching indication.

19. A computer program, comprising instructions which, when executed by a processor, cause an apparatus to perform the actions of the method of any of claims 1 to 6 or 7 to 8.

20. A computer program product, comprising computer readable medium and a computer program according to claim 19 stored on the computer readable medium.