WO2025241066A1

WO2025241066A1 - Beam sweeping factor

Info

Publication number: WO2025241066A1
Application number: PCT/CN2024/094252
Authority: WO
Inventors: Morten Toft; Rafael Cauduro Dias De Paiva; Lei Du; Bent Henneberg RYSGAARD; Lars Dalsgaard
Original assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy; Nokia Technologies Oy
Current assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy; Nokia Technologies Oy
Priority date: 2024-05-20
Filing date: 2024-05-20
Publication date: 2025-11-27
Anticipated expiration: 2026-11-20

Abstract

Example embodiments of the present disclosure provide a solution for optimization of using a reduced receiver (Rx) Beam Sweeping Factor (BSF). In an example method, a terminal device counts a first number of at least one out-of-sync event. The terminal device enables, based on determining that the first number reaches a first threshold, a reduced Beam Sweeping Factor (BSF) in which multiple beams are activated at a time. The terminal device counts a second number of at least one in-sync event. The terminal device disables the reduced Beam Sweeping Factor (BSF) based on determining that the second number reaches a second threshold. In this way, the UE mobility performance at the cell edge can be improved, while in respective direction(s) with a minimal impact to the UE power consumption.

Description

BEAM SWEEPING FACTOR

FIELD

Various example embodiments relate to the field of communication, and in particular, to devices, methods, apparatuses, and a computer readable medium for optimization of using a reduced receiver (Rx) Beam Sweeping Factor (BSF) .

BACKGROUND

A communication network can be seen as a facility that enables communications between two or more communication devices, or provides communication devices access to a data network. A mobile or wireless communication network is one example of a communication network.

Such communication networks operate in accordance with standards, such as those promulgated by 3GPP (Third Generation Partnership Project) or ETSI (European Telecommunications Standards Institute) . Examples of such standards include the so-called 5G (5th Generation) standard or other standards promulgated by 3GPP.

SUMMARY

In general, example embodiments of the present disclosure provide a solution for optimization of using a reduced receiver (Rx) Beam Sweeping Factor (BSF) , especially for fast beam sweeping (FBS) usage controlled by quality metrics for cell evaluation.

In a first aspect, there is provided a terminal device. The terminal device comprises at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the terminal device at least to: count a first number of at least one out-of-sync event; enable, based on determining that the first number reaches a first threshold, a reduced Beam Sweeping Factor (BSF) in which multiple beams are activated at a time; count a second number of at least one in-sync event; and disable the reduced Beam Sweeping Factor (BSF) based on determining that the second number reaches a second threshold.

In a second aspect, there is provided a network device. The network device comprises at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the network device at least to: transmit, to a terminal device, configuration information for enabling or disabling of reduced Beam Sweeping Factor (BSF) in which multiple beams are activated at a time. The configuration information at least comprises a first threshold for at least one out-of-sync event and a second threshold for at least one in-sync event.

In a third aspect, there is provided a method. The method comprises: counting a first number of at least one out-of-sync event; enabling, based on determining that the first number reaches a first threshold, reduced Beam Sweeping Factor (BSF) in which multiple beams are activated at a time; counting a second number of at least one in-sync event; and disabling the reduced Beam Sweeping Factor (BSF) based on determining that the second number reaches a second threshold.

In a fourth aspect, there is provided a method. The method comprises: transmitting, to a terminal device, configuration information for enabling or disabling of reduced Beam Sweeping Factor (BSF) in which multiple beams are activated at a time. The configuration information at least comprises a first threshold for at least one out-of-sync event and a second threshold for at least one in-sync event.

In a fifth aspect, there is provided an apparatus. The apparatus comprises: means for counting a first number of at least one out-of-sync event; means for enabling, based on determining that the first number reaches a first threshold, reduced Beam Sweeping Factor (BSF) in which multiple beams are activated at a time; means for counting a second number of at least one in-sync event; and means for disabling reduced Beam Sweeping Factor (BSF) based on determining that the second number reaches a second threshold.

In a sixth aspect, there is provided an apparatus. The apparatus comprises: means for transmitting, to a terminal device, configuration information for enabling or disabling of reduced Beam Sweeping Factor (BSF) in which multiple beams are activated at a time. The configuration information at least comprises a first threshold for at least one out-of-sync event and a second threshold for at least one in-sync event.

In a seventh aspect, there is provided a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least method of the above third aspect or fourth aspect.

In an eighth aspect, there is provided a computer program comprising instructions, which, when executed by an apparatus, cause the apparatus to perform at least the method of the above third aspect or fourth aspect.

In a ninth aspect, there is provided a terminal device. The terminal device comprises: first counting circuitry configured to count a first number of at least one out-of-sync event; enabling circuitry configured to enable, based on determining that the first number reaches a first threshold, a reduced Beam Sweeping Factor (BSF) in which multiple beams are activated at a time; second counting circuitry configured to count a second number of at least one in-sync event; and disabling circuitry configured to disable the reduced Beam Sweeping Factor (BSF) based on determining that the second number reaches a second threshold.

In a tenth aspect, there is provided a network device. The network device comprises: transmitting circuitry configured to transmit, to a terminal device, configuration information for enabling or disabling of reduced Beam Sweeping Factor (BSF) in which multiple beams are activated at a time. The configuration information at least comprises a first threshold for at least one out-of-sync event and a second threshold for at least one in-sync event.

It is to be understood that the summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Some example embodiments will now be described with reference to the accompanying drawings, in which:

FIG. 1A illustrates an example communication network in which embodiments of the present disclosure may be implemented;

FIG. 1B illustrates example multi-Rx downlink (DL) reception of a user equipment (UE) where one beam is activated at a time;

FIG. 1C illustrates example multi-Rx DL reception of a UE where two beams are activated at a time;

FIG. 2 illustrates an example of a process flow in accordance with some example embodiments of the present disclosure;

FIG. 3A illustrates an example timeline with respect to block error rate (BLER) ;

FIG. 3B illustrates an example timeline with Q_out and Q_in events, indicating the events from lower layer indicating Out Of Sync (OOS) or In Sync (IS) , in accordance with some example embodiments of the present disclosure;

FIG. 3C illustrates an another example timeline with Q_out and Q_in events, indicating the events from lower layer indicating Out Of Sync (OOS) or In Sync (IS) , in accordance with some example embodiments of the present disclosure;

FIG. 3D illustrates how the radio link monitoring (RLM) is controlled by counters N310 and N311 and timer T310;

FIG. 4 illustrates a flowchart of an example method implemented at a terminal device in accordance with some other embodiments of the present disclosure;

FIG. 5 illustrates a flowchart of an example method implemented at a network device in accordance with some other embodiments of the present disclosure;

FIG. 6 illustrates a simplified block diagram of a device that is suitable for implementing some example embodiments of the present disclosure; and

FIG. 7 illustrates a block diagram of an example of a computer-readable medium in accordance with some example embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numerals represent the same or similar elements.

DETAILED DESCRIPTION

Principles of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. The disclosure described herein can be implemented in various manners other than the ones described below.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

References in the present disclosure to “one embodiment, ” “an embodiment, ” “an example embodiment, ” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

It shall be understood that although the terms “first” and “second” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the listed terms.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a” , “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” , “comprising” , “has” , “having” , “includes” and/or “including” , when used herein, specify the presence of stated features, elements, and/or components etc., but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof. As used herein, “at least one of the following: <a list of two or more elements>” and “at least one of <a list of two or more elements>” and similar wording, where the list of two or more elements are joined by “and” or “or” , mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

As used in this application, the term “circuitry” may refer to one or more or all of the following:

(a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and

(b) combinations of hardware circuits and software, such as (as applicable) :

(i) a combination of analog and/or digital hardware circuit (s) with software/firmware and

(ii) any portions of hardware processor (s) with software (including digital signal processor (s) ) , software, and memory (ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

(c) hardware circuit (s) and or processor (s) , such as a microprocessor (s) or a portion of a microprocessor (s) , that requires software (for example, firmware) for operation, but the software may not be present when it is not needed for operation.

This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

As used herein, the term “network” , “communication network” or “data network” refers to a network following any suitable communication standards, such as long term evolution (LTE) , LTE-advanced (LTE-A) , wideband code division multiple access (WCDMA) , high-speed packet access (HSPA) , narrow band Internet of things (NB-IoT) , wireless fidelity (Wi-Fi) and so on. Furthermore, the communications between a terminal device and a network device/element in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the fourth generation (4G) , 4.5G, the future fifth generation (5G) , IEEE 802.11 communication protocols, and/or any other protocols either currently known or to be developed in the future. Embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communications, there will of course also be future type communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system.

As used herein, the term “network device” refers to a node in a communication network via which a terminal device receives services (e.g., positioning services) therefrom. The network device may refer to a core network device or access network device, such as base station (BS) or an access point (AP) or a transmission and reception point (TRP) , for example, a node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , a NR NB (also referred to as a gNB) , a remote radio unit (RRU) , a radio header (RH) , a remote radio head (RRH) , a WiFi device, a relay, a low power node such as a femto, a pico, and so forth, depending on the applied terminology and technology. In the following description, the terms “network device” , “AP device” , “AP” and “access point” may be used interchangeably.

The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example rather than limitation, a terminal device may also be referred to as a communication device, user equipment (UE) , a Subscriber Station (SS) , a Portable Subscriber Station, a Mobile Station (MS) , a station (STA) or station device, or an Access Terminal (AT) . The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA) , portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE) , laptop-mounted equipment (LME) , USB dongles, smart devices, wireless customer-premises equipment (CPE) , an Internet of Things (IoT) device, a watch or other wearable, a head-mounted display (HMD) , a vehicle, a drone, a medical device and applications (for example, remote surgery) , an industrial device and applications (for example, a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts) , a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. In the following description, the terms “station” , “station device” , “STA” , “terminal device” , “communication device” , “terminal” , “user equipment” and “UE” may be used interchangeably.

Principles and embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Reference is first made to FIG. 1A, which illustrates an example communication system 100 in which embodiments of the present disclosure may be implemented. The system 100 includes a plurality of network devices, such as a network device 111 and a network device 112. The network devices 111, 112 serve respective areas 101 and 102 (also called as cells 101 and 102) using different frequency bands in both DL and UL. Such a frequency band may also be referred to as an operating frequency band of the corresponding network device.

The system 100 also includes one or more terminal devices, such as terminal devices 120, 121, 122. The terminal devices 120, 121, 122 are capable of connecting and communicating in an UL and DL with either or both of the network devices 111, 112 as long as the terminal devices located within the corresponding cells. In communication systems, an UL refers to a link in a direction from a terminal device to a network device, and a DL refers to a link in a direction from the network device to the terminal device. In addition to communicating the terminal devices 120, 121, 122, the network devices 111, 112 may also communicate with each other, for example, via a backhaul link.

It is to be understood that the number of network devices and terminal devices is only for the purpose of illustration without suggesting any limitations. The system 100 may include any suitable number of network devices and terminal devices adapted for implementing embodiments of the present disclosure. Although not shown, it would be appreciated that one or more terminal devices may be located in the cell 101 or 102.

Communications in the communication system 100 may be implemented according to any proper communication protocol (s) , comprising, but not limited to, cellular communication protocols of the first generation (1G) , the second generation (2G) , the third generation (3G) , the fourth generation (4G) and the fifth generation (5G) and on the like, wireless local network communication protocols such as Institute for Electrical and Electronics Engineers (IEEE) 802.11 and the like, and/or any other protocols currently known or to be developed in the future. Moreover, the communication may utilize any proper wireless communication technology, comprising but not limited to: Code Division Multiple Access (CDMA) , Frequency Division Multiple Access (FDMA) , Time Division Multiple Access (TDMA) , Frequency Division Duplex (FDD) , Time Division Duplex (TDD) , Multiple-Input Multiple-Output (MIMO) , Orthogonal Frequency Division Multiple (OFDM) , Discrete Fourier Transform spread OFDM (DFT-s-OFDM) and/or any other technologies currently known or to be developed in the future.

The coverage ranges of the cells 101, 102 of the network devices 111 is tightly related to the operating frequency bands of the network devices 111, 112. FIG. 1A shows an example where the operating frequency bands of the network devices 111, 112 are different, with the operating frequency band of the network device 111 higher than the operating frequency band of the network device 112. It is very possible that the coverage range of the cell 101 is smaller than that of the cell 102, due to a more serious path-loss situation in the high frequency band system. In the shown example, the cell 101 is overlapped with the cell 102. The large cell 102 may sometimes be referred to as a macro cell and the network device 112 may be referred to as a macro base station, while the relatively small cell 101 may sometimes be referred to as a small cell and the network device 111 may be referred to as a small base station. As a specific example, the network device 111 may be operating at sub6GHz, such as 3.5 GHz, while the network device 112 may be operating at a millimetre-wave (mmW) frequency band, such as at 28 GHz. It is to be understood that other operating frequency bands are also possible for the network devices 111, 112.

In some scenarios, the cell 101 and/or the cell 102 may have an asymmetric UL and DL budget. Such asymmetric budget easily happens in a cell with a high frequency band. For example, in a case of operating at the mmW frequency band, the different budget between the UL and DL may be up to 25 dB. FIG. 1A shows that the asymmetric UL and DL in the cell 101. For example, the cell 101 includes an UL coverage area 103 and a DL coverage area that is the same as the range of the cell 101. The UL coverage area 103 is smaller than the DL coverage area. For example, up to 25 dB budget difference may lead to a situation where the UL coverage area is only about 1/4 of the DL coverage area. The main reasons are the small UL transmission power of terminal devices and/or smaller UL transmission beamforming gain, as compared with the DL case.

Due to the UL/DL coverage asymmetry in the cell 101, there may be a situation where a terminal device is still communicating with the network device 101 in a DL with a high quality while the UL from that terminal device to the network device 101 is worse. For example, the terminal device 120 was previously in the coverage area 103 and had both UL and DL connections with the network device 111. After movement, the terminal device 120 is still in the cell 101 of the network device 111 and can work in the DL with the network device 111. However, at this time, the UL quality from the terminal device 120 to the network device 111 is decreased. For the terminal device 121 within the coverage area 103, the UL and DL with the network device 111 both works well. For the terminal device 122 outside the cell 101 but within the cell 102, it may establish a connection with the network device 112 in both UL and DL. To enable UL communication of the terminal device 120, as mentioned above, in embodiments of the present disclosure, the terminal device 120 is allowed to switch only its UL to the network device 112 and still maintain its DL with the network device 111.

It would be appreciated that although the frequency band of the network device 111 has been described as being higher than that of the network device 112, in some other cases, the frequency band of the network device 112 may be higher than or equal to that of the network device 111. In these cases, there may also occur when a terminal device has a good DL and a worse UL with one of the network devices 111, 112 and may thus switch the UL to the other one of the network devices 111, 112.

Generally, under normal operating conditions, a UE maintains its connection towards a primary serving cell and completes a handover to change the primary serving cell when necessary. The base station instructs the UE to return the measurement report through the radio resource control (RRC) message when the conditions for handover are satisfied. This allows the base station to take a handover decision and subsequently initiate the handover procedure.

The UE may experience radio link failure (RLF) if a handover procedure fails or if a handover procedure is not initiated when it is required. The former may result from congestion at the target cell or a change in radio conditions which leads to poor target cell coverage. The latter may result from a missing neighbour relationship or a triggering threshold which initiates the handover procedure too late. The UE may also experience radio link failure if the 5G coverage becomes weak and the UE is unable to complete an intersystem handover.

The UE shall monitor the downlink radio link quality based on the reference signal (RS) configured as radio link monitoring (RLM) -RS resource (s) in order to detect the downlink radio link quality of the primary cell (PCell) , primary secondary Cell (PSCell) , and deactivated PSCell if configured with bfd-and-RLM with value true. The configured RLM-RS resources can be all synchronization signal block (SSBs) , or all channel state information (CSI) -RSs, or a mix of SSBs and CSI-RSs.

On each RLM-RS resource, the UE shall estimate the downlink radio link quality and compare it to the thresholds Q_out and Q_in for the purpose of monitoring downlink radio link quality of the cell.

The threshold Q_out is defined as the level at which the downlink radio link cannot be reliably received and shall correspond to the out-of-sync block error rate (BLER_out) . For SSB based radio link monitoring, Q_{out_SSB} is derived based on the hypothetical Physical Downlink Control Channel (PDCCH) transmission parameters. For CSI-RS based radio link monitoring, Q_{out_CSI-RS} is derived based on the hypothetical PDCCH transmission parameters.

The threshold Q_in is defined as the level at which the downlink radio link quality can be received with significantly higher reliability than at Q_out and shall correspond to the in-sync block error rate (BLER_in) . For SSB based radio link monitoring, Q_{in_SSB} is derived based on the hypothetical PDCCH transmission parameters. For CSI-RS based radio link monitoring, Q_{in_CSI-RS} is derived based on the hypothetical PDCCH transmission parameters.

In 5G frequency range 2 (FR2) , it has been agreed that UE always use directional beams for DL and uplink (UL) data. For simplicity and for UE power saving reasons, it is assumed that UE has one directional beam activated at a time.

For the UE to cover all directions around the UE, it has been agreed that 8 beams in different directions are needed. As a result, whenever the UE needs to monitor a cell, it will need to sweep the 8 different beams to make sure that one beam is pointing against the cell. Therefore, beam sweeping factor (BSF) = 8 is used for setting requirement for measurements. As illustrated in FIG. 1B, for multi-Rx downlink (DL) reception of the UE, one beam is activated at a time.

Moreover, fast beam sweeping (FBS) may also be used when the UE supports multi-RX reception. In this case, the UE may have two beams activated at a time, and hence a BSF=4 is used. As illustrated in FIG. 1C, for multi-Rx DL reception of the UE, two beams are activated at a time. That is, the UE monitors two directions simultaneously. It should be noted that, although in FIG. 1C, two beams activated at a time have opposite directions, the two beams activated at a time may have any relative directions between them. More than two beams may be activated at a time; that is, the UE monitors more than two directions simultaneously.

The effect is that when using FBS (e.g., BSF=4) , the UE can perform measurements in half of the time as compared to BSF=8, but at the cost of higher UE power consumption. This can be helpful for measurements used for mobility where the time to perform the measurements is critical.

In general, the reduction of layer 3 (L3) measurement delay by using lower beam sweeping factor (BSF) will come with a cost for the UE in terms of increased UE power consumption. Therefore, it is desirable from a UE implementation perspective, that the reduced BSF is enabled only when there is a benefit in doing so. Otherwise, the UE might use the beam sweeping factor (currently 8 has been adopted when defining the measurement requirements) . One situation where a reduced BSF for L3 measurements can enhance user perceived quality is close to mobility events, such as handover, since longer L3 measurement delay may lead to handover errors and longer interruption.

Using the optimized BSF to improve the mobility performance is considered. In particular, when the UE is in cell edge and experiencing link variation, it is expected that the UE can perform the L3 measurement in a faster way so that the handover delay can be reduced.

Hence, there is a need to link the use of FBS, especially FBS for L3 measurements, to the procedure for radio link failure detection. When the UE is approaching radio link failure, it is of high importance that the UE with minimum delay can identify and measure a new potential primary cell, to which it can direct the re-establishment procedure or select a candidate target cell for handover.

In some scenarios, the present disclosure mainly relates to the UE on a single FR2 carrier connected to a primary cell. For example, how the UE can use FBS for L3 measurements during and in a specified time period before and after a period with high block error rate (BLER) . This is important for both reducing UE power consumption, as well as for improving the UE mobility performance at the cell edge.

Therefore, some embodiments of the present disclosure propose a solution for optimization of using a reduced Rx Beam Sweeping Factor (BSF) . In this solution, a terminal device counts a first number of at least one out-of-sync event. Also, the terminal device enables, based on determining that the first number reaches a first threshold, a reduced Beam Sweeping Factor (BSF) in which multiple beams are activated at a time. Then, the terminal device counts a second number of at least one in-sync event. In addition, the terminal device disables the reduced Beam Sweeping Factor (BSF) based on determining that the second number reaches a second threshold. By implementing the example embodiments of the present disclosure, the UE mobility performance at the cell edge can be improved, while in respective direction (s) with a minimal impact to the UE power consumption.

For illustrative purposes, principles and example embodiments of the present disclosure will be described below with reference to FIG. 1A to FIG. 7. However, it is to be noted that these embodiments are given to enable the skilled in the art to understand inventive concepts of the present disclosure and implement the solution as proposed herein, and not intended to limit scope of the present application in any way.

FIG. 2 illustrates an example of a process flow 200 in accordance with some example embodiments of the present disclosure. For ease of understanding, the process flow 200 will be described with reference to FIG. 1A. It would be appreciated that although the process flow 200 has been described referring to the communication network 100 of FIG. 1A, this process flow 200 may be likewise applied to other similar communication scenarios.

As shown in FIG. 2, at 202, a network device 260 may transmit, to a terminal device 240, configuration information 204 for enabling or disabling of reduced Beam Sweeping Factor (BSF) in which multiple beams are activated at a time.

Accordingly, at 206, the terminal device 240 may receive, from the network device 260, the configuration information 204. Thereafter, at 210, the terminal device 240 may count a first number of at least one out-of-sync event. At 212, the terminal device 240 may enable, based on determining that the first number reaches a first threshold, a reduced Beam Sweeping Factor (BSF) in which multiple beams are activated at a time.

Thereafter, at 214, the terminal device 240 may count a second number of at least one in-sync event. At 216, the terminal device 240 may disable the reduced Beam Sweeping Factor (BSF) based on determining that the second number reaches a second threshold.

In some embodiments, when enabling the reduced Beam Sweeping Factor (BSF) , the terminal device 240 may enable the reduced Beam Sweeping Factor (BSF) when determining that the first number reaches the first threshold.

In some embodiments, when disabling the reduced Beam Sweeping Factor (BSF) , the terminal device 240 may start a timer when the second number reaches the second threshold, and disable the reduced Beam Sweeping Factor (BSF) at expiry of the timer.

In some embodiments, the configuration information 204 at least comprises the first threshold and the second threshold. Additionally, in some embodiments, the configuration information 204 further configures the timer.

Alternatively, in some embodiments, configuration information for enabling or disabling the reduced Beam Sweeping Factor (BSF) is predefined.

FIG. 3A illustrates an example timeline with respect to block error rate (BLER) , and FIG. 3B illustrates an example timeline with Q_out and Q_in events, indicating the events from lower layer indicating Out Of Sync (OOS) or In Sync (IS) , in accordance with some example embodiments of the present disclosure.

As illustrated in FIG. 3B, fast beam sweeping (FBS) is enabled by using mRXOOS_Counter, mRXIN_Counter, and timer mRXIN_Timer. For example, mRXOOS_Counter may be set as the first threshold as mentioned above, mRXIN_Counter may be set as the second threshold as mentioned above, and the timer mRXIN_Timer may be set as the timer as mentioned above.

In FIG. 3B, the Q_out and Q_in events are used as triggers for the legacy BLER targets, where BLER_out = 10%and BLER_in = 2%. In general, the Q_out event refers to an event that relates to the downlink radio link quality estimated by the UE reaching or above the threshold Q_out, and the Q_in event refers to an event that relates to the downlink radio link quality estimated by the UE reaches or below the threshold Q_in.

For example, the Q_out and Q_in events are used to control the use of FBS for L3 measurements. The rules for controlling the use of FBS can be explicitly indicated by the network or pre-defined.

For the procedure controlled by the network, it proposes to define a new set of parameters to configure the FBS control procedure.

For example, to enable the FBS, when counting the number of Q_out signals to be received from lower layers before the FBS is activated, the mRXOOS_Counter is defined, where each Q_out signal corresponds to a Q_out event. It allows the network to configure the UE to start using FBS during period (s) of high BLER, which may indicate a high potential of handover.

Similarly, when counting the number of Q_in signals to be received from lower layers until FBS is deactivated, the mRXIN_Counter is defined, where each Q_in signal corresponds to a Q_in event. In order to further extend the FBS period, the mRXIN_Timer is defined, which is started when the count of Q_in events reaches the value of mRXIN_Counter. At the expiry of the mRXIN_Timer, FBS is disabled.

The procedure for enabling and disabling FBS as illustrated in FIG. 3B may be described as follows.

The number of consecutive Q_out events is counted. When the number of consecutive Q_out events reaches the value of mRXOOS_Counter, then the FBS is enabled.

Then, the number of consecutive Q_in events is counted. When the number of consecutive Q_in events reaches the value of mRXIN_Counter, then the timer mRXIN_timer is started.

In addition, at expiry of the timer mRXIN_timer, the FBS is disabled.

FIG. 3D illustrates how the radio link monitoring (RLM) is controlled by counters N310 and N311 and timer T310. At expiry of the timer T310, the radio link failure is detected.

As illustrated in FIGS. 3A and 3B in combination with FIG. 3D, with the above mentioned procedure, it is possible to mandate the UE to start use FBS before RLM detection of physical layer problem, and keep using FBS after recovery of physical layer problem.

Table 1Table shows an example of how the proposed timers and parameters can be defined. In the information element SpCellConfig, it proposes to add a new information element mRX-TimersAndConstants-r19. It will contain mRXOOS_Counter, mRXIN_Counter, and mRXIN_Timer. In the example below, the proposed timers and parameters are in bold type.

Table 1. Exemplary timers and parameters added into the SpCellConfig information element

Referring back to FIG. 2, in some embodiments, the first threshold is set to 1. For example, the FBS based measurement may be triggered/activated implicitly by Q_out, e.g., the first Q_out indication from lower layers. In some embodiments, when disabling the reduced Beam Sweeping Factor (BSF) , the terminal device 240 may disable the reduced Beam Sweeping Factor (BSF) when determining, based on the at least one in-sync event, that a link is recovered. For example, in this situation, no network signaling is needed.

In some embodiments, the terminal device is configured with a first configuration comprising a first out-of-sync block error rate (BLER) for determining a first set of out-of-sync events and a first in-sync BLER for determining a first set of in-sync events; the terminal device is configured with a second configuration comprising a second out-of-sync BLER for determining a second set of out-of-sync events and a second in-sync BLER for determining a second set of in-sync events; the second set of out-of-sync events are used for enabling the reduced Beam Sweeping Factor (BSF) , and the first set of out-of-sync events are not used for enabling the beam sweeping; and the second set of in-sync events are used for disabling of the reduced Beam Sweeping Factor (BSF) , and the first set of in-sync events are not used for disabling of the reduced Beam Sweeping Factor (BSF) .

In some embodiments, the first out-of-sync BLER is 10%and the first in-sync BLER is 2%. Additionally or alternatively, the second out-of-sync BLER is less than 10%and the second in-sync BLER is less than 2%.

FIG. 3C illustrates an another example timeline with Qout and Qin events, indicating the events from lower layer indicating Out Of Sync (OOS) or In Sync (IS) , in accordance with some example embodiments of the present disclosure.

For example, as an enhancement to the above procedure, implementation of new additional BLER targets for the Q_out and Q_in used for enabling FBS may be proposed. The out-of-sync BLER target is less than 10%and the in-sync BLER target is less than 2%. As an example, it proposes to use BLER_out = 6%and BLER_in = 1%as shown in FIG 3C. With the updated BLER targets, the FBS period can be extended, which means both to start earlier and to end later. The proposed BLER targets are optional, the network may select and signal to the UE to use legacy BLER targets (BLER_out = 10%and BLER_in = 2%) or the proposed BLER targets (e.g., BLER_out = 6%and BLER_in = 1%as shown in FIG 3C) .

For example, the criteria for the Q_out and Q_in events are defined as a single configuration in Table 2, where the BLER targets are: BLER of 10%for Q_out and 2%for Q_in.

Table 2. Exemplary definitions of BLER_out and BLER_in

(Out-of-sync and in-sync block error rates)

Some embodiments of the present disclosure propose to add a second configuration for the Q_out and Q_in events used for FBS control. An example is shown in Table 3. In the proposed SpCellConfig above, the mRXInSyncOutOfSyncThreshold is added and shown in bold type, which will indicate to the UE which of the configurations to use for FBS procedure. The example may use fixed configurations with both values, while the values may also be given explicitly.

Table 3. Example of mRXInSyncOutOfSyncThreshold configurations

Referring back to FIG. 2, in some embodiments, the at least one out-of-sync event comprises multiple consecutive out-of-sync events, and the at least one in-sync event comprises multiple consecutive in-sync events. In some embodiments, the reduced Beam Sweeping Factor (BSF) is used for at least one layer 3 (L3) measurement, and the terminal device 240 may further transmit a report of the at least one L3 measurement to the network device 260. Accordingly, the network device 260 may further receive the report of the at least one L3 measurement from the terminal device 240.

The present disclosure proposes linking bad radio link performance to the UE’s use of FBS. As mentioned above, the use of FBS is power consuming for the UE. However, during bad radio link performance conditions, it might be worth for the UE to ensure early detection of a new potential primary cell. Moreover, the present disclosure proposes the definition of new parameters for controlling the FBS procedure.

FIG. 4 illustrates a flowchart of an example method 400 implemented at a terminal device in accordance with some other embodiments of the present disclosure. For ease of understanding, the method 400 will be described from the perspective of the terminal device 240 with reference to FIG. 2.

At block 410, the terminal device may count a first number of at least one out-of-sync event. At block 420, the terminal device may enable, based on determining that the first number reaches a first threshold, a reduced Beam Sweeping Factor (BSF) in which multiple beams are activated at a time. At block 430, the terminal device may count a second number of at least one in-sync event. At block 440, the terminal device may disable the reduced Beam Sweeping Factor (BSF) based on determining that the second number reaches a second threshold.

In some embodiments, when enabling the reduced Beam Sweeping Factor (BSF) , the terminal device may enable the reduced Beam Sweeping Factor (BSF) when determining that the first number reaches the first threshold. In some embodiments, the first threshold is set to 1.

Additionally, in some embodiments, when disabling the reduced Beam Sweeping Factor (BSF) , the terminal device may start a timer when the second number reaches the second threshold, and disable the reduced Beam Sweeping Factor (BSF) at expiry of the timer.

Alternatively, in some embodiments, when disabling the reduced Beam Sweeping Factor (BSF) , the terminal device may disable the reduced Beam Sweeping Factor (BSF) when determining, based on the at least one in-sync event, that a link is recovered.

In some embodiments, the first out-of-sync BLER is 10%and the first in-sync BLER is 2%; or the second out-of-sync BLER is less than 10%and the second in-sync BLER is less than 2%; or both.

Additionally, in some embodiments, the terminal device may further receive, from a network device, configuration information for enabling or disabling the reduced Beam Sweeping Factor (BSF) , wherein the configuration information at least comprises the first threshold and the second threshold.

Additionally, in some embodiments, the configuration information further configures a timer, the timer is started when the second number reaches the second threshold, and the reduced Beam Sweeping Factor (BSF) is disabled at expiry of the timer.

In some embodiments, the at least one out-of-sync event comprises multiple consecutive out-of-sync events, and the at least one in-sync event comprises multiple consecutive in-sync events.

In some embodiments, the reduced Beam Sweeping Factor (BSF) is used for at least one layer 3 (L3) measurement, and the terminal device may further transmit a report of the at least one L3 measurement to a network device.

FIG. 5 illustrates a flowchart of an example method 500 implemented at a network device in accordance with some other embodiments of the present disclosure. For ease of understanding, the method 500 will be described from the perspective of the network device 260 with reference to FIG. 2.

At block 510, the network device may transmit, to a terminal device, configuration information for enabling or disabling of reduced Beam Sweeping Factor (BSF) in which multiple beams are activated at a time. The configuration information at least comprises a first threshold for at least one out-of-sync event and a second threshold for at least one in-sync event.

In some embodiments, the reduced Beam Sweeping Factor (BSF) is enabled based on determining that the first number reaches the first threshold, and the reduced Beam Sweeping Factor (BSF) is disabled based on determining that the second number reaches the second threshold.

In some embodiments, the reduced Beam Sweeping Factor (BSF) is enabled when determining that the first number reaches the first threshold. In some embodiments, the first threshold is set to 1.

Alternatively, in some embodiments, the reduced Beam Sweeping Factor (BSF) is disabled when determining, based on the at least one in-sync event, that a link is recovered.

In some embodiments, the network device may further transmit, to the terminal device, a first configuration and a second configuration. The first configuration comprises a first out-of-sync block error rate (BLER) for determining a first set of out-of-sync events and a first in-sync BLER for determining a first set of in-sync events, and the second configuration comprises a second out-of-sync BLER for determining a second set of out-of-sync events and a second in-sync BLER for determining a second set of in-sync events; the second set of out-of-sync events are used for enabling the reduced Beam Sweeping Factor (BSF) , and the first set of out-of-sync events are not used for enabling the reduced Beam Sweeping Factor (BSF) ; and the second set of in-sync events are used for disabling of the reduced Beam Sweeping Factor (BSF) , and the first set of in-sync events are not used for disabling of the reduced Beam Sweeping Factor (BSF) .

In some embodiments, at least one of the following: the first out-of-sync BLER is 10%and the first in-sync BLER is 2%; or the second out-of-sync BLER is less than 10%and the second in-sync BLER is less than 2%; or both.

In some embodiments, the reduced Beam Sweeping Factor (BSF) is used for at least one layer 3 (L3) measurement, and the network device is further caused to receive a report of the at least one L3 measurement from the terminal device.

In some embodiments, an apparatus capable of performing any of the method 400 (for example, the terminal device 240) may comprise means for performing the respective steps of the method 400. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

In some embodiments, the apparatus comprises means for counting a first number of at least one out-of-sync event; means for enabling, based on determining that the first number reaches a first threshold, a reduced Beam Sweeping Factor (BSF) in which multiple beams are activated at a time; means for counting a second number of at least one in-sync event; and means for disabling the reduced Beam Sweeping Factor (BSF) based on determining that the second number reaches a second threshold.

In some embodiments, the means for enabling the reduced Beam Sweeping Factor (BSF) comprises means for enabling the reduced Beam Sweeping Factor (BSF) when determining that the first number reaches the first threshold. In some embodiments, the first threshold is set to 1.

In some embodiments, the means for disabling the reduced Beam Sweeping Factor (BSF) comprises means for starting a timer when the second number reaches the second threshold, and means for disabling the reduced Beam Sweeping Factor (BSF) at expiry of the timer.

In some embodiments, the means for disabling the reduced Beam Sweeping Factor (BSF) comprises means for disabling the reduced Beam Sweeping Factor (BSF) when determining, based on the at least one in-sync event, that a link is recovered.

In some embodiments, the apparatus is configured with a first configuration comprising a first out-of-sync block error rate (BLER) for determining a first set of out-of-sync events and a first in-sync BLER for determining a first set of in-sync events; the apparatus is configured with a second configuration comprising a second out-of-sync BLER for determining a second set of out-of-sync events and a second in-sync BLER for determining a second set of in-sync events; the second set of out-of-sync events are used for enabling the reduced Beam Sweeping Factor (BSF) , and the first set of out-of-sync events are not used for enabling the beam sweeping; and the second set of in-sync events are used for disabling of the reduced Beam Sweeping Factor (BSF) , and the first set of in-sync events are not used for disabling of the reduced Beam Sweeping Factor (BSF) .

In some embodiments, the apparatus further comprises means for receiving, from a network device, configuration information for enabling or disabling the reduced Beam Sweeping Factor (BSF) , wherein the configuration information at least comprises the first threshold and the second threshold.

In some embodiments, the configuration information further configures a timer, the timer is started when the second number reaches the second threshold, and the reduced Beam Sweeping Factor (BSF) is disabled at expiry of the timer.

In some embodiments, configuration information for enabling or disabling the reduced Beam Sweeping Factor (BSF) is predefined.

In some embodiments, the reduced Beam Sweeping Factor (BSF) is used for at least one layer 3 (L3) measurement, and the apparatus further comprises means for transmitting a report of the at least one L3 measurement to a network device.

In some embodiments, the apparatus further comprises means for performing other steps in some embodiments of the method 400. In some embodiments, the means comprises at least one processor and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus.

In some embodiments, an apparatus capable of performing any of the method 500 (for example, the network device 260) may comprise means for performing the respective steps of the method 500. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

In some embodiments, the apparatus comprises means for transmitting, to a terminal device, configuration information for enabling or disabling of reduced Beam Sweeping Factor (BSF) in which multiple beams are activated at a time. The configuration information at least comprises a first threshold for at least one out-of-sync event and a second threshold for at least one in-sync event.

In some embodiments, the reduced Beam Sweeping Factor (BSF) is disabled when determining, based on the at least one in-sync event, that a link is recovered.

In some embodiments, the apparatus further comprises means for transmitting, to the terminal device, a first configuration and a second configuration. The first configuration comprises a first out-of-sync block error rate (BLER) for determining a first set of out-of-sync events and a first in-sync BLER for determining a first set of in-sync events, and the second configuration comprises a second out-of-sync BLER for determining a second set of out-of-sync events and a second in-sync BLER for determining a second set of in-sync events; the second set of out-of-sync events are used for enabling the reduced Beam Sweeping Factor (BSF) , and the first set of out-of-sync events are not used for enabling the reduced Beam Sweeping Factor (BSF) ; and the second set of in-sync events are used for disabling of the reduced Beam Sweeping Factor (BSF) , and the first set of in-sync events are not used for disabling of the reduced Beam Sweeping Factor (BSF) .

In some embodiments, the apparatus further comprises means for performing other steps in some embodiments of the method 500. In some embodiments, the means comprises at least one processor and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the performance of the apparatus.

FIG. 6 illustrates a simplified block diagram of a device 600 that is suitable for implementing some example embodiments of the present disclosure. The device 600 may be provided to implement a communication device, for example, the terminal device 240 or the network device 260 as shown in FIG. 2. As shown, the device 600 includes one or more processors 610, one or more memories 620 coupled to the processor 610, and one or more communication modules 640 coupled to the processor 610.

The communication module 640 is for bidirectional communications. The communication module 640 has at least one antenna to facilitate communication. The communication interface may represent any interface that is necessary for communication with other network elements.

The processor 610 may be of any type suitable to the local technical network and may include one or more of the following: general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 600 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

The memory 620 may include one or more non-volatile memories and one or more volatile memories. Examples of the non-volatile memories include, but are not limited to, a Read Only Memory (ROM) 624, an electrically programmable read only memory (EPROM) , a flash memory, a hard disk, a compact disc (CD) , a digital video disk (DVD) , and other magnetic storage and/or optical storage. Examples of the volatile memories include, but are not limited to, a random access memory (RAM) 622 and other volatile memories that will not last in the power-down duration.

A computer program 630 includes computer executable instructions that are executed by the associated processor 610. The program 630 may be stored in the ROM 624. The processor 610 may perform any suitable actions and processing by loading the program 630 into the RAM 622.

The embodiments of the present disclosure may be implemented by means of the program 630 so that the device 600 may perform any process of the disclosure as discussed with reference to FIGS. 4 and 5. The embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

In some example embodiments, the program 630 may be tangibly contained in a computer-readable medium which may be included in the device 600 (such as in the memory 620) or other storage devices that are accessible by the device 600. The device 600 may load the program 630 from the computer-readable medium to the RAM 622 for execution. The computer-readable medium may include any types of tangible non-volatile storage, such as ROM, EPROM, a flash memory, a hard disk, CD, DVD, and the like.

FIG. 7 illustrates a block diagram of an example of a computer-readable medium 1000 in accordance with some example embodiments of the present disclosure. The computer-readable medium 700 has the program 630 stored thereon. It is noted that although the computer-readable medium 700 is depicted in form of CD or DVD in FIG. 7, the computer-readable medium 700 may be in any other form suitable for carry or hold the program 630.

Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it is to be understood that the block, apparatus, system, technique or method described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the method 400 or 500 as described above with reference to FIG. 4 or 5. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowcharts and/or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

In the context of the present disclosure, the computer program codes or related data may be carried by any suitable carrier to enable the device, apparatus or processor to perform various processes and operations as described above. Examples of the carrier include a signal, computer-readable medium, and the like.

The computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium. A computer-readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the computer-readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM) , a read-only memory (ROM) , an erasable programmable read-only memory (EPROM or Flash memory) , an optical fiber, a portable compact disc read-only memory (CD-ROM) , an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. The term “non-transitory, ” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM) .

Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

Although the present disclosure has been described in languages specific to structural features and/or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

A terminal device comprising:

at least one processor; and

at least one memory storing instructions that, when executed by the at least one processor, cause the terminal device at least to:

count a first number of at least one out-of-sync event;

enable, based on determining that the first number reaches a first threshold, a reduced Beam Sweeping Factor (BSF) in which multiple beams are activated at a time;

count a second number of at least one in-sync event; and

disable the reduced Beam Sweeping Factor (BSF) based on determining that the second number reaches a second threshold.
The terminal device of claim 1, wherein the terminal device is caused to enable the reduced Beam Sweeping Factor (BSF) by:

enabling the reduced Beam Sweeping Factor (BSF) when determining that the first number reaches the first threshold.
The terminal device of claim 2, wherein the first threshold is set to 1.
The terminal device of any of claims 1-3, wherein the terminal device is caused to disable the reduced Beam Sweeping Factor (BSF) by:

starting a timer when the second number reaches the second threshold; and

disabling the reduced Beam Sweeping Factor (BSF) at expiry of the timer.
The terminal device of any of claims 1-3, wherein the terminal device is caused to disable the reduced Beam Sweeping Factor (BSF) by:

disabling the reduced Beam Sweeping Factor (BSF) when determining, based on the at least one in-sync event, that a link is recovered.
The terminal device of any of claims 1-5, wherein:

the terminal device is configured with a first configuration comprising a first out-of-sync block error rate (BLER) for determining a first set of out-of-sync events and a first in-sync BLER for determining a first set of in-sync events;

the terminal device is configured with a second configuration comprising a second out-of-sync BLER for determining a second set of out-of-sync events and a second in-sync BLER for determining a second set of in-sync events;

the second set of out-of-sync events are used for enabling the reduced Beam Sweeping Factor (BSF) , and the first set of out-of-sync events are not used for enabling the beam sweeping; and

the second set of in-sync events are used for disabling of the reduced Beam Sweeping Factor (BSF) , and the first set of in-sync events are not used for disabling of the reduced Beam Sweeping Factor (BSF) .
The terminal device of claim 6, wherein at least one of the following:

the first out-of-sync BLER is 10%and the first in-sync BLER is 2%; or

the second out-of-sync BLER is less than 10%and the second in-sync BLER is less than 2%.
The terminal device of any of claims 1-7, wherein the terminal device is further caused to:

receive, from a network device, configuration information for enabling or disabling the reduced Beam Sweeping Factor (BSF) , wherein the configuration information at least comprises the first threshold and the second threshold.
The terminal device of claim 8, wherein the configuration information further configures a timer, the timer is started when the second number reaches the second threshold, and the reduced Beam Sweeping Factor (BSF) is disabled at expiry of the timer.
The terminal device of any of claims 1-7, wherein configuration information for enabling or disabling the reduced Beam Sweeping Factor (BSF) is predefined.
The terminal device of any of claims 1-10, wherein the at least one out-of-sync event comprises multiple consecutive out-of-sync events, and the at least one in-sync event comprises multiple consecutive in-sync events.
The terminal device of any of claims 1-11, wherein the reduced Beam Sweeping Factor (BSF) is used for at least one layer 3 (L3) measurement, and the terminal device is further caused to transmit a report of the at least one L3 measurement to a network device.
A network device comprising:

at least one processor; and

at least one memory storing instructions that, when executed by the at least one processor, cause the network device at least to:

transmit, to a terminal device, configuration information for enabling or disabling of reduced Beam Sweeping Factor (BSF) in which multiple beams are activated at a time,

wherein the configuration information at least comprises a first threshold for at least one out-of-sync event and a second threshold for at least one in-sync event.
The network device of claim 13, wherein the reduced Beam Sweeping Factor (BSF) is enabled based on determining that the first number reaches the first threshold, and the reduced Beam Sweeping Factor (BSF) is disabled based on determining that the second number reaches the second threshold.
The network device of claim 14, wherein the reduced Beam Sweeping Factor (BSF) is enabled when determining that the first number reaches the first threshold.
The network device of claim 15, wherein the first threshold is set to 1.
The network device of any of claims 14-16, wherein the configuration information further configures a timer, the timer is started when the second number reaches the second threshold, and the reduced Beam Sweeping Factor (BSF) is disabled at expiry of the timer.
The network device of any of claims 14-16, wherein the reduced Beam Sweeping Factor (BSF) is disabled when determining, based on the at least one in-sync event, that a link is recovered.
The network device of any of claims 13-18, wherein the network device is further caused to:

transmit, to the terminal device, a first configuration and a second configuration, wherein the first configuration comprises a first out-of-sync block error rate (BLER) for determining a first set of out-of-sync events and a first in-sync BLER for determining a first set of in-sync events, and the second configuration comprises a second out-of-sync BLER for determining a second set of out-of-sync events and a second in-sync BLER for determining a second set of in-sync events;

the second set of out-of-sync events are used for enabling the reduced Beam Sweeping Factor (BSF) , and the first set of out-of-sync events are not used for enabling the reduced Beam Sweeping Factor (BSF) ; and

the second set of in-sync events are used for disabling of the reduced Beam Sweeping Factor (BSF) , and the first set of in-sync events are not used for disabling of the reduced Beam Sweeping Factor (BSF) .
The network device of claim 19, wherein at least one of the following:

the first out-of-sync BLER is 10%and the first in-sync BLER is 2%; or

the second out-of-sync BLER is less than 10%and the second in-sync BLER is less than 2%.
The network device of any of claims 13-20, wherein the at least one out-of-sync event comprises multiple consecutive out-of-sync events, and the at least one in-sync event comprises multiple consecutive in-sync events.
The network device of any of claims 13-21, wherein the reduced Beam Sweeping Factor (BSF) is used for at least one layer 3 (L3) measurement, and the network device is further caused to receive a report of the at least one L3 measurement from the terminal device.
A method comprising:

counting a first number of at least one out-of-sync event;

enabling, based on determining that the first number reaches a first threshold, reduced Beam Sweeping Factor (BSF) in which multiple beams are activated at a time;

counting a second number of at least one in-sync event; and

disabling the reduced Beam Sweeping Factor (BSF) based on determining that the second number reaches a second threshold.
A method comprising:

transmitting, to a terminal device, configuration information for enabling or disabling of reduced Beam Sweeping Factor (BSF) in which multiple beams are activated at a time,

wherein the configuration information at least comprises a first threshold for at least one out-of-sync event and a second threshold for at least one in-sync event.
An apparatus comprising:

means for counting a first number of at least one out-of-sync event;

means for enabling, based on determining that the first number reaches a first threshold, reduced Beam Sweeping Factor (BSF) in which multiple beams are activated at a time;

means for counting a second number of at least one in-sync event; and

means for disabling reduced Beam Sweeping Factor (BSF) based on determining that the second number reaches a second threshold.
An apparatus comprising:

means for transmitting, to a terminal device, configuration information for enabling or disabling of reduced Beam Sweeping Factor (BSF) in which multiple beams are activated at a time,

wherein the configuration information at least comprises a first threshold for at least one out-of-sync event and a second threshold for at least one in-sync event.
A non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least method of any of claims 23-24.