Method for enhancing handover performance in wireless communication systems

Abstract

Method for enhancing handover performance in wireless communication systems, characterized by, receiving measurement configuration for AI / ML enabled feature / functional groups (FGs) for data collection and logging of measurements, and measuring RSRP / RSRQ values of serving cell and the neighboring cells according to its measurement configuration; predicting the occurrence of measurement events based on internal statistics, history of measurement results, and configured prediction models; if the UE predicts that a measurement event will occur within a configured prediction horizon, the UE selecting a Time-To-Trigger (TTT) value from a mapping table, and using the selected TTT for measurement reporting.

Description

[0001] TITLE

[0002] Method for enhancing handover performance in wireless communication systems

[0003] TECHNICAL FIELD

[0004] This application generally is related to wireless communication and to techniques for user equipment (UE) mobility support and enhanced handover performance.

[0005] BACKGROUND

[0006] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, and / or the like). Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency-division multiple access (FDMA) systems, orthogonal frequency-division multiple access (OFDMA) systems, single-carrier frequency-division multiple access (SC-FDMA) systems, time division synchronous code division multiple access (TD-SCDMA) systems, and Long Term Evolution (LTE). LTE / LTE-Advanced is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by the Third Generation Partnership Project (3GPP).

[0007] A wireless network may include a number of base stations (BSs) that can support communication for a number of user equipment (UEs). A user equipment (UE) may communicate with a base station (BS) via the downlink and uplink. The downlink (or forward link) refers to the communication link from the BS to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the BS. As will be described in more detail herein, a BS may be referred to as a Node B, a gNB, an access point (AP), a radio head, a transmit receive point (TRP), a New Radio (NR) BS, a 5G Node B, and / or the like. The above multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different user equipment to communicate on a municipal, national, regional, and even global level. New Radio (NR), which may also be referred to as 5G, is a set of enhancements to the LTE mobile standard promulgated by the Third Generation Partnership Project (3GPP). NR is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) (CP- OFDM) on the downlink (DL), using CP-OFDM and / or SC-FDM (e.g., also known as discrete Fourier transform spread OFDM (DFT-s-OFDM)) on the uplink (UL), as well as supporting beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation. As the demand for mobile broadband access continues to increase, further improvements in LTE, NR, and other radio access technologies remain useful.

[0008] Relevant for this application is the L3 handover procedure. The UE continuously measures signal qualities (such as RSRP, RSRQ, SINR) of neighboring cells and reports these to the serving base station (eNodeB / gNB) according to configured measurement events. Based on measurement reports and mobility criteria, the serving base station (source cell) decides if a handover is needed and selects a suitable target cell. The source base station sends a handover request to the target base station, which allocates resources and responds with a handover request acknowledgment. This exchange is performed using Layer 3 (RRC and higher) signaling messages. The source base station sends an RRC handover command to the UE. Upon receiving this command, the UE disconnects from the source cell and synchronizes with the target cell. The UE accesses the target cell and completes the random access procedure if required. It then establishes a connection with the target base station. The UE sends a handover complete message to the target base station, which informs the core network. The resources in the source cell are then released. The basis for this is network-controlled mobility, which comes in two flavors: beam level mobility and cell level mobility. Beam-level mobility is handled in lower layers, MAC and the physical layer and is essentially identical to beam management. Celllevel mobility, on the other hand, requires RRC signaling and implies changing the serving cell. The device is configured with measurements to perform on candidate cells, filtering of the measurements, and event-triggered reporting to the network. Since the network is in charge of determining when the device should be moved to a different cell, the device location is known to the network on a cell level.

[0009] Within 3GPP RRC specification several reporting events are defined. It mentions 5G NR Event A1 , Event A2, Event A3, Event A4, Event A5 and Event A6. Based on following events, triggering of measurement reports occur. Event A1 (Serving becomes better than threshold). Event A2 (Serving becomes worse than threshold). • Event A3 (Neighbor becomes offset better than SpCell). Event A4 (Neighbor becomes better than threshold). Event A5 (SpCell becomes worse than thresholdl and neighbor becomes better than threshold2). Event A6 (Neighbor becomes offset better than SCell). The B1 event occurs when the measurement of the signal received from the neighboring inter-RAT (4G) cell with an inter-RAT offset ofn and ocn becomes greater than that of a threshold. The B2 event occurs when the measurement of the signal received from the PCell is below a threshold and the 4G inter-RAT measurements become greater than a second threshold.

[0010] Handover can be triggered due to changing radio conditions. UE's connection with the source cell may weaken. Once a certain threshold has been reached, the network decides to handover the UE to another cell that has better radio conditions. The network knows these conditions based on measurement reports sent by the UE.

[0011] US 2022 / 0030453 Al titled "TECHNIQUES FOR UE MOBILITY PREDICTION BASED RADIO RESOURCE MANAGEMENT discloses a user equipment (UE), which may determine a mobility prediction for the UE. The UE may determine one or more radio resource management (RRM) measurement parameters based at least in part on the mobility prediction. The UE may perform one or more RRM measurements based at least in part on the one or more RRM measurement parameters. Numerous other aspects are provided.

[0012] US 2023 / 0413152 Al titled "AI / ML BASED MOBILITY RELATED PREDICTION FOR HANDOVER discloses a source network node and a UE may obtain at least one mobility related prediction associated with the UE or at least one target network node, the at least one mobility related prediction being derived by at least one neural network, and the source network node may handover the UE from the source network node to the at least one target network node based on the at least one mobility related prediction. The target network node may receive the handover request, obtain at least one mobility related prediction associated with the UE or the target network node, and output for transmission a handover request ACK, the handover request ACK based at least in part on the at least one mobility related prediction.

[0013] US 2022 / 0116838 Al titled "HANDOVER OPTIMIZATION BASED ON UE MOBILITY PREDICTION" discloses a user equipment (UE), which may determine one or more candidate base stations for a handover procedure for the UE. The UE may transmit an indication of the one or more candidate base stations to a serving base station.

[0014] The present disclosure solves the cited problem by the proposed embodiments and describes a AI / ML-based method for enhancing handover performance in wireless communication systems, characterized by, that UE checks, if the mapping is received and measures RSRP / RSRQ values of serving and neighboring cells according to its measurement configuration, UE predicts the occurrence of measurement events based on internal statistics and history of measurement results, if the UE predicted measurement event occurs within configured prediction horizon, the UE selects a Time-To-Trigger (TTT) value from the mapping table and the selected Time-To- Trigger (TTT) is used for measurement reporting.

[0015] In some embodiments of the method according to the first aspect, the method is characterized by, that UE evaluates RSRP / RSRQ change rate once a measurement event is predicted to occur within configured time horizon and adapts TTT value accordingly.

[0016] In some embodiments of the method according to the first aspect, the method is characterized by, UE continuously evaluates RSRP / RSRQ change rates and adapts TTT value accordingly.

[0017] In some embodiments of the method according to the first aspect, the method is characterized by, that the selected TTT is used for measurement reporting

[0018] In some embodiments of the method according to the first aspect, the method is characterized by, that the selected TTT being used for measurement reporting is A3 or predicted time instant at which RLF may occur in the serving cell.

[0019] In some embodiments of the method according to the first aspect, the method is characterized by, that mapping between RSRP / RSRQ and TTT values is provided via SIB signaling.

[0020] In some embodiments of the method according to the first aspect, the method is characterized by, that mapping between RSRP / RSRQ and TTT values is provided via UE-specific signaling.

[0021] In some embodiments of the method according to the first aspect, the method is characterized by, that the UE-specific signaling is RRC signaling.

[0022] In some embodiments of the method according to the first aspect, the method is characterized by, that mapping between RSRP / RSRQ and TTT values is provided by SIB and UE-specific signaling.

[0023] In some embodiments of the method according to the first aspect, the method is characterized by, that mapping between RSRP / RSRQ and TTT values is provided by the predefinition in specification of the wireless communication system. According to a second aspect, the present disclosure relates to a AI / ML-based method for enhancing handover performance in wireless communication systems, characterized by, that the gNB determines mapping of RSRP / RSRQ change rates and TTT values, provides mapping, checks if at least one UE report is received, provides updated mapping and / or updated handover and / or measurement configurations.

[0024] According to a third aspect, the present disclosure relates to an Apparatus for AI / ML- based method for enhancing handover performance in wireless communication systems, that the apparatus comprising a wireless transceiver, a processor coupled with a memory in which computer program instructions are stored, said instructions being configured to carry out the steps according to the first aspect.

[0025] According to a fourth aspect, the present disclosure relates to an Apparatus for AI / ML-based method for enhancing handover performance in wireless communication systems, that the apparatus comprising a wireless transceiver, a processor coupled with a memory in which computer program instructions are stored, said instructions being configured to carry out the steps according to the second aspect.

[0026] According to a fifth aspect, the present disclosure relates to user equipment comprising an apparatus according the third aspect.

[0027] According to a sixth aspect, the present disclosure relates to gNB comprising an apparatus according the fourth aspect.

[0028] According to a seventh aspect, the present disclosure relates to a Wireless communication systems for AI / ML-based method for enhancing handover performance comprises at least one user equipment according the third aspect, gNB according to fourth aspect, whereby the user equipment and the gNB each comprises a processor coupled with a memory in which computer program instructions are stored, said instructions being configured to carry out the steps of the according to the first and second aspect. According to a further aspect, the present disclosure relates to a computer program product comprising instructions which, when executed by at least one processor, configure said at least one processor to carry out a method according to the first aspect and / or said at least one processor to carry out a method for exchanging data according to any one of the embodiments of the present disclosure. The computer program product can use any programming language, and can be in the form of source code, object code, or in any intermediate form between source code and object code, such as in a partially compiled form, or in any other desirable form.

[0029] According to a further aspect, the present disclosure relates to a computer-readable storage medium comprising instructions which, when executed by at least one processor, configure said at least one processor to carry out a method according to any one of the embodiments of the present disclosure.

[0030] Beneficially, the proposed aspects can reduce the radio link failures and enhance handover performance.

[0031] BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 shows the conditions for triggering handover in 5G Figure 2 shows the UE side flow

[0033] Figure 3 shows the network side (gNB) flow

[0034] DETAILED DESCRIPTION

[0035] The detailed description set forth below, with reference to annexed drawings, is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In particular, although terminology from 3GPP 5G NR may be used in this disclosure to exemplify embodiments herein, this should not be seen as limiting the scope of the invention.

[0036] Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Other embodiments, however, are contained within the scope of the subject matter disclosed herein, the disclosed subject matter should not be construed as limited to only the embodiments set forth herein; rather, these embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.

[0037] Generally, all terms used herein are to be interpreted according to their ordinary meaning in the relevant technical field, unless a different meaning is clearly given and / or is implied from the context in which it is used. All references to a / an / the element, apparatus, component, means, step, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any methods disclosed herein do not have to be performed in the exact order disclosed, unless a step is explicitly described as following or preceding another step and / or where it is implicit that a step must follow or precede another step. Any feature of any of the embodiments disclosed herein may be applied to any other embodiment, wherever appropriate. Likewise, any advantage of any of the embodiments may apply to any other embodiments, and vice versa. Other objectives, features and advantages of the enclosed embodiments will be apparent from the following description.

[0038] In some embodiments, a more general term “network node” may be used and may correspond to any type of radio network node or any network node, which communicates with a UE (directly or via another node) and / or with another network node. Examples of network nodes are NodeB, MeNB, ENB, a network node belonging to MCG or SCG, base station (BS), multi-standard radio (MSR) radio node such as MSR BS, eNodeB, gNodeB, network controller, radio network controller (RNC), base station controller (BSC), relay, donor node controlling relay, base transceiver station (BTS), access point (AP), transmission points, transmission nodes, RRU, RRH, nodes in distributed antenna system (DAS), core network node (e.g. Mobile Switching Center (MSC), Mobility Management Entity (MME), etc), Operations & Maintenance (O&M), Operations Support System (OSS), Self Optimized Network (SON), positioning node (e.g. Evolved- Serving Mobile Location Centre (E-SMLC)), Minimization of Drive Tests (MDT), test equipment (physical node or software), etc.

[0039] In some embodiments, the non-limiting term user equipment (UE) or wireless device may be used and may refer to any type of wireless device communicating with a network node and / or with another UE in a cellular or mobile communication system. Examples of UE are target device, device to device (D2D) UE, machine type UE or UE capable of machine to machine (M2M) communication, PDA, PAD, Tablet, mobile terminals, smart phone, laptop embedded equipped (LEE), laptop mounted equipment (LME), USB dongles, UE category Ml, UE category M2, ProSe UE, V2V UE, V2X UE, etc.

[0040] Additionally, terminologies such as base station / gNodeB and UE should be considered non-limiting and do in particular not imply a certain hierarchical relation between the two; in general, “gNodeB” could be considered as device 1 and “UE” could be considered as device 2 and these two devices communicate with each other over some radio channel. And in the following the transmitter or receiver could be either gNodeB (gNB), or UE.

[0041] As will be appreciated by one skilled in the art, aspects of the embodiments may be embodied as a system, apparatus, method, or program product. Accordingly, embodiments may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects.

[0042] For example, the disclosed embodiments may be implemented as a hardware circuit comprising custom very-large-scale integration (“VLSI”) circuits or gate arrays, off- the-shelf semiconductors such as logic chips, transistors, or other discrete components. The disclosed embodiments may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices, or the like. As another example, the disclosed embodiments may include one or more physical or logical blocks of executable code which may, for instance, be organized as an object, procedure, or function.

[0043] Furthermore, embodiments may take the form of a program product embodied in one or more computer readable storage devices storing machine readable code, computer readable code, and / or program code, referred hereafter as code. The storage devices may be tangible, non- transitory, and / or non-transmission. The storage devices may not embody signals. In a certain embodiment, the storage devices only employ signals for accessing code.

[0044] Any combination of one or more computer readable medium may be utilized. The computer readable medium may be a computer readable storage medium. The computer readable storage medium may be a storage device storing the code. The storage device may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, holographic, micromechanical, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing.

[0045] More specific examples (a non-exhaustive list) of the storage device would include the following: 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), a portable compact disc readonly memory (“CD-ROM”), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device.

[0046] Code for carrying out operations for embodiments may be any number of lines and may be written in any combination of one or more programming languages including an object- oriented programming language such as Python, Ruby, Java, Smalltalk, C++, or the like, and conventional procedural programming languages, such as the “C” programming language, or the like, and / or machine languages such as assembly languages. The code may execute entirely on the user’s computer, partly on the user’s computer, as a stand-alone software package, partly on the user’s computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user’s computer through any type of network, including a local area network (“LAN”), wireless LAN (“WLAN”), or a wide area network (“WAN”), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider (“ISP”)).

[0047] Furthermore, the described features, structures, or characteristics of the embodiments may be combined in any suitable manner. In the following description, numerous specific details are provided, such as examples of programming, software modules, user selections, network transactions, database queries, database structures, hardware modules, hardware circuits, hardware chips, etc., to provide a thorough understanding of embodiments. One skilled in the relevant art will recognize, however, that embodiments may be practiced without one or more of the specific details, or with other methods, components, materials, and so forth. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of an embodiment. Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment, but mean “one or more but not all embodiments” unless expressly specified otherwise. The terms “including,” “comprising,” “having,” and variations thereof mean “including but not limited to,” unless expressly specified otherwise. An enumerated listing of items does not imply that any or all of the items are mutually exclusive, unless expressly specified otherwise. The terms “a,” “an,” and “the” also refer to “one or more” unless expressly specified otherwise. Aspects of the embodiments are described below with reference to schematic flowchart diagrams and / or schematic block diagrams of methods, apparatuses, systems, and program products according to embodiments. It will be understood that each block of the schematic flowchart diagrams and / or schematic block diagrams, and combinations of blocks in the schematic flowchart diagrams and / or schematic block diagrams, can be implemented by code. This code may be provided to a processor of a general-purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the fimctions / acts specified in the flowchart diagrams and / or block diagrams.

[0048] The code may also be stored in a storage device that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the storage device produce an article of manufacture including instructions which implement the function / act specified in the flowchart diagrams and / or block diagrams.

[0049] The code may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus, or other devices to produce a computer implemented process such that the code which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart diagrams and / or block diagrams.

[0050] The flowchart diagrams and / or block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of apparatuses, systems, methods, and program products according to various embodiments. In this regard, each block in the flowchart diagrams and / or block diagrams may represent a module, segment, or portion of code, which includes one or more executable instructions of the code for implementing the specified logical function(s). In the context of AI / ML, the terms feature group and functional group can be used interchangeably.

[0051] It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the Figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more blocks, or portions thereof, of the illustrated Figures.

[0052] Although various arrow types and line types may be employed in the flowchart and / or block diagrams, they are understood not to limit the scope of the corresponding embodiments. Indeed, some arrows or other connectors may be used to indicate only the logical flow of the depicted embodiment. For instance, an arrow may indicate a waiting or monitoring period of unspecified duration between enumerated steps of the depicted embodiment. It will also be noted that each block of the block diagrams and / or flowchart diagrams, and combinations of blocks in the block diagrams and / or flowchart diagrams, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and code.

[0053] The description of elements in each figure may refer to elements of proceeding figures. Like numbers refer to like elements in all figures, including alternate embodiments of like elements.

[0054] The detailed description set forth below, with reference to the figures, is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. For instance, although 3GPP terminology, from e.g., 5G NR, may be used in this disclosure to exemplify embodiments herein, this should not be seen as limiting the scope of the present disclosure.

[0055] The disclosure is related to wireless communication system, which may be for example a 5G NR wireless communication system. More specifically, it represents a RAN of the wireless communication system, which is used exchange data with UEs via radio signals. For example, the RAN may send data to the UEs (downlink, DL), for instance data received from a core network (CN). The RAN may also receive data from the UEs (uplink, UL), which data may be forwarded to the CN.

[0056] In the examples illustrated, the RAN comprises one base station, BS. Of course, the RAN may comprise more than one BS to increase the coverage of the wireless communication system. Each of these BSs may be referred to as NB, eNodeB (or eNB), gNodeB (or gNB, in the case of a 5G NR wireless communication system), an access point or the like, depending on the wireless communication standard(s) implemented.

[0057] The UEs are located in a coverage of the BS. The coverage of the BS corresponds for example to the area in which UEs can decode a PDCCH transmitted by the BS.

[0058] An example of a wireless device suitable for implementing any method, discussed in the present disclosure, performed at a UE corresponds to an apparatus that provides wireless connectivity with the RAN of the wireless communication system, and that can be used to exchange data with said RAN. Such a wireless device may be included in a UE. The UE may for instance be a cellular phone, a wireless modem, a wireless communication device, a handheld device, a laptop computer, or the like. The UE may also be an Internet of Things (loT) equipment, like a wireless camera, a smart sensor, a smart meter, smart glasses, a vehicle (manned or unmanned), a global positioning system device, etc., or any other equipment that may run applications that need to exchange data with remote recipients, via the wireless device.

[0059] The wireless device comprises one or more processors and one or more memories. The one or more processors may include for instance a central processing unit (CPU), a digital signal processor (DSP), a field-programmable gate array (FPGA), an application specific integrated circuit (ASIC), etc. The one or more memories may include any type of computer readable volatile and non-volatile memories (magnetic hard disk, solid-state disk, optical disk, electronic memory, etc.). The one or more memories may store a computer program product, in the form of a set of programcode instructions to be executed by the one or more processors to implement all or part of the steps of a method for exchanging data, performed at a UE’s side, according to any one of the embodiments disclosed herein.

[0060] The wireless device can comprise also a main radio, MR, unit. The MR unit corresponds to a main wireless communication unit of the wireless device, used for exchanging data with BSs of the RAN using radio signals. The MR unit may implement one or more wireless communication protocols, and may for instance be a 3G, 4G, 5G, NR, WiFi, WiMax, etc. transceiver or the like. In preferred embodiments, the MR unit corresponds to a 5G NR wireless communication unit.

[0061] Figure 1 shows the conditions for triggering handover in 5G

[0062] The Figure 1 shows A3 event for which the target cell is better than the source cell by a certain threshold for at least Time-To-Trigger (TTT) duration.

[0063] Currently, UE uses TTT values, which are statically configured by the gNB. Highspeed UEs face the risk of Radio Link Failure (RLF), if handover is not completed, before RSRP / RSRQ values of the serving cell becomes too weak. The solved problem as mentioned before is how to adjust TTT value for enhancing handover performance and mitigating radio link failure.

[0064] Figure 2 shows the UE side flow and in principle the problem is solved by, that the UE selects a TTT value based on the change rate of RSRP / RSRQ values. The benefits of this approach are enhanced handover performance and less radio link failures and UE mobility is considered for triggering measurement reporting. The UE determines the change rate of RSRP / RSRQ values to select a Time-To- Trigger (TTT) value from the mapping table. Time-To-Trigger (TTT) is a timer parameter used in mobility management, especially for handover and cell reselection procedures. When a measurement event (such as a neighboring cell’s signal becoming stronger than the serving cell) is detected by the user equipment (UE), the TTT timer is started. The event must remain true i.e. , the condition must be continuously met for the entire duration of the TTT. Only if the condition persists for the full TTT duration will the network or device trigger the corresponding action (such as initiating a handover or reselection). If the condition stops being true before the TTT expires, the timer is reset and no action is taken. TTT helps prevent unnecessary or rapid switching (ping-pong effect) between cells due to short-term fluctuations in signal quality. It ensures that handovers or reselections are only triggered when a new cell consistently provides better service, improving user experience and network efficiency.

[0065] The UE determines the change rate of RSRQ / RSRQ within a time window and predicts the instant at which a measurement event (e.g., A3) will be triggered. The UE also determine the time instant at which RLF may occur in the serving cell.

[0066] AR / At = (R2 - / ?1 ) / (t2 - t1 )

[0067] RSRP / RSRQ change rate TTT value

[0068] A(R1~R2) / At TTT1

[0069] A(R2~R3) / At TTT2

[0070] A(RN1~RN2) / At TTTN

[0071] The UE measures RSRP / RSRQ values of serving and (intra- / inter-frequency) neighboring cells according to its measurement configuration). Based on internal statistics e.g., incl. time, date, location, speed, heading data and history of measurement results, the UE predicts the occurrence of measurement events, e.g., A3, B2, RLF. If the UE predicted measurement event occurs within configured prediction horizon, the UE selects a TTT value from the mapping table. The UE evaluates RSRP / RSRQ change rate once a measurement event is predicted to occur within configured time horizon and adapts TTT value accordingly. The UE continuously evaluates RSRP / RSRQ change rates and adapts TTT value accordingly. This selected TTT is used for measurement reporting, e.g., A3 or predicted time instant at which RLF may occur in the serving cell.

[0072] The mapping between RSRP / RSRQ and TTT values can be provided via: SIB signaling, UE-specific signaling (e.g., RRC), SIB (initial) and UE-specific signaling e.g., updates, Pre-defined in specification.

[0073] Reference Signals Received Power (RSRP) and Reference Signal Received Quality (RSRQ) are key measures of signal level and quality for networks. In cellular networks, when a mobile device moves from cell to cell and performs cell selection / reselection and handover, it has to measure the signal strength / quality of the neighbor cells. In the procedure of handover, the LTE specification provides the flexibility of using RSRP, RSRQ, or both. Reference Signal Received Power (RSRP) is an RSSI type of measurement. It is the power of the LTE Reference Signals spread over the full bandwidth and narrowband. A minimum of -20 dB SINR (of the S-Synch channel) is needed to detect RSRP / RSRQ.

[0074] Reference Signal Received Quality (RSRQ) is Quality considering also RSSI and the number of used Resource Blocks (N) RSRQ = (N * RSRP) I RSSI measured over the same bandwidth. RSRQ is a C / 1 type of measurement and it indicates the quality of the received reference signal. The RSRQ measurement provides additional information when RSRP is not sufficient to make a reliable handover or cell reselection decision.

[0075] Generally spoken the network determines and provides via a gNB mapping of RSRP / RSRQ change rates and TTT values.

[0076] The predict measurements events could be related to mobility condition and / or Reference Signal Received Power (RSRP) and / or channel quality. The UE determines the mobility indicator which can be RSRP. In 3GPP (specifically LTE and 5G NR), RSRP is a standardized measurement that quantifies the average received power of the reference signals transmitted by a cell over the considered frequency bandwidth. RSRP is defined as: "The linear average over the power contributions (in Watts) of the resource elements that carry cell-specific reference signals within the considered measurement frequency bandwidth". In LTE, these reference signals are known as Cell-Specific Reference Signals (CRS). In 5G NR, similar measurements are made using Synchronization Signal (SS-RSRP) or Channel State Information Reference Signals (CSI-RSRP). RSRP measures the strength of the desired signal from a specific cell, not the overall signal quality (which would also consider interference and noise). It is a critical metric for cell selection, reselection, and handover decisions by the user equipment (UE). Reporting Range: RSRP values typically range from about -140 dBm (very weak) to -44 dBm (very strong). Unlike RSSI, which measures total received power, including interference and noise, RSRP focuses only on the power of the reference signals, providing a more accurate indication of the serving cell’s signal strength.

[0077] Mobility conditions refer to the set of mechanisms, policies, and procedures that manage how user equipment (UE)-such as smartphones or loT devices-maintains connectivity and service continuity as it moves between different cells, base stations, or network areas within a mobile network. The network keeps track of the UE’s location by requiring periodic registration updates. This ensures the device is still active, within coverage, and able to receive services. Updates are also triggered when the UE moves outside its current registration or tracking area. When a UE moves from one cell or base station (gNB in 5G) to another, the network coordinates a handover to maintain ongoing sessions without interruption. In 5G, this is managed by the Access and Mobility Management Function (AMF), which handles procedures such as Xn handover between gNBs using the XnAP protocol. Additionally the Policy Control Function (PCF) provides access and mobility management policies to the AMF, which enforces them. These policies can include service area restrictions, allowed or disallowed tracking areas, and the maximum number of areas a UE can traverse. Furthermore, the mapping between RSRP / RSRQ and TTT values can be provided via Radio Resource Control (RRC) signaling. RRC establishes, maintains, and releases the signaling connection between the UE and the network, sets up, reconfigures, and releases radio bearers, which are logical channels for data transmission, delivers essential network configuration and operational parameters to all UEs in a cell, handles procedures such as handovers, cell reselection, and paging to support user movement and maintain service continuity, manages security parameters for encryption and integrity protection, allocates and optimizes radio resources to ensure efficient network operation and quality of service and helps manage UE power consumption by controlling active and idle states. RRC operates as a state machine, with the UE transitioning between states such as idle not actively connected and connected actively exchanging data, depending on network activity and user behavior. Each state determines the level of network resources allocated to the UE and impacts both service quality and battery consumption.

[0078] Furthermore, the mapping between RSRP / RSRQ and TTT values can be done by System Information Block SIB (initial) and UE-specific signaling (e.g., updates). SIBs are structured messages broadcast by the network (base station) to all user devices (UEs) within a cell. Each SIB contains specific types of system information that are essential for devices to access, operate in, and move within the mobile network. Each SIB carries different information, such as cell selection parameters, network identifiers, mobility settings, access restrictions, and neighbor cell data. There are multiple SIBs (e.g., SIB1 , SIB2, SIB3, etc.), each with a defined role. For example, SIB1 typically contains cell selection information and scheduling details for other SIBs, while SIB2 and higher carry more detailed configuration and mobility information. SIBs are periodically broadcast on downlink channels so that any UE can receive them, even before establishing a dedicated connection with the network.

[0079] Each SIB has its own repetition period and scheduling, allowing UEs to know when to read the information they need. SIB1 : Cell selection info, PLMN identity, tracking area code, scheduling for other SIBs. SIB2: Common channel configuration and access parameters. SIB3 and above: Mobility, neighbor cell, and other advanced parameters. A SIB (System Information Block) is a broadcast message containing vital network and cell information, enabling user devices to access, operate, and move within the mobile network

[0080] Furthermore, the mapping between RSRP / RSRQ and TTT values can be done by predefinition in the specification of the implementation of the wireless communication network. They might refer to a set of messages broadcast by the network to all user devices (UEs) within a cell. These messages provide essential details that devices need to access, operate in, and move between cells within the mobile network. This provides unique identifiers for the network, location area, and cell. This helps the device recognize which network and cell it is communicating with. It Includes information required for the device to determine if it can access the cell, such as cell selection and reselection parameters and describes the structure of control channels, random access channel configurations, and other radio-related settings.

[0081] Furthermore, it supplies data about neighboring cells to support handover and mobility management and it may include notifications for emergency warning systems like ETWS or CMAS and it contains parameters relevant for all devices, such as paging and system access settings.

[0082] Figure 3 shows the network side (gNB) flow. The gNB determines mapping of RSRP / RSRQ change rates and TTT values, provides mapping check if at least one UE report is received and provides updated mapping and / or updated handover and / or measurement configurations.

Claims

CLAIMS1. A method performed by a user equipment (UE) for enhancing handover performance in wireless communication systems, characterized by:• receiving measurement configuration for AI / ML enabled feature / functional groups (FGs) for data collection and logging of measurements, and measuring RSRP / RSRQ values of serving cell and the neighbouring cells according to its measurement configuration;• predicting the occurrence of measurement events based on internal statistics, history of measurement results, and configured AI / ML-based prediction models;• If the UE predicts that a measurement event will occur within a configured prediction horizon, the UE selecting a Time-To-Trigger (TTT) value from a mapping table, and using the selected TTT for measurement reporting.

2. A method according to claim 1 , wherein the UE is configured with periodic or event-triggered reporting of predicted and / or actual RRM measurements.

3. A method according to claim 1 , wherein UE evaluates RSRP / RSRQ change rate once a measurement event is predicted to occur within configured time horizon and adapts TTT value accordingly.

4. A method according to claim 1 , wherein UE continuously evaluates RSRP / RSRQ change rates and adapts TTT value accordingly.

5. A method according to any of the previous claims, wherein the selected TTT value is used for measurement reporting.

6. A method according to any of the previous claims, wherein the selected TTT value being used for measurement reporting is A3 or predicted time instant at which RLF may occur in the serving cell.

7. A method according to any of the previous claims, wherein mapping between RSRP / RSRQ and TTT values is provided via SIB signaling.

8. A method according to any of the previous claims, wherein mapping between RSRP / RSRQ and TTT values is provided via UE-specific signaling and / or RRC signalling.

9. A method according to claims 1 to 8, wherein mapping between RSRP / RSRQ and TTT values is provided by SIB and UE-specific signaling.

10. A method according to claims 1 to 8, wherein mapping between RSRP / RSRQ and TTT values is provided by the predefinition in specification of the wireless communication system.

11. An AI / ML-based method performed by a base station (e.g., gNB) for enhancing handover performance in wireless communication systems, characterized by,• determining the mapping of RSRP / RSRQ change rates and TTT values,• Providing the mapping to the UE,• Checking, if at least one UE report is received,• providing updated mapping and / or updated handover and / or measurement configurations.

12. Apparatus for AI / ML-based method for enhancing handover performance in wireless communication systems, that the apparatus comprising a wireless transceiver, a processor coupled with a memory in which computer program instructions are stored, said instructions being configured to carry out the steps of the claims 1 to 10.

13. Apparatus for AI / ML-based method for enhancing handover performance in wireless communication systems, that the apparatus comprising a wireless transceiver, a processor coupled with a memory in which computer program instructions are stored, said instructions being configured to carry out the steps of the claim 11 .

14. User Equipment comprising an apparatus according to claim 12.

15. Base station (e.g., gNB) comprising an apparatus according to claim 13.

16. Wireless communication systems for AI / ML-based method for enhancing handover performance comprises at least one user equipment according to claim 14, at least one gNB according to claim 15, whereby the user equipment and the gNB each comprises a processor coupled with a memory in which computer program instructions are stored, said instructions being configured to carry out steps of the claims 1 to 11 .

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