Rank-driven measurement event and reporting

Abstract

Embodiments of the present disclosure relate to methods, apparatuses, and computer programs for rank-driven measurement events and reporting. A user equipment (UE) comprising: at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the UE to at least: determine a first rank associated with a first set of beams, the first set of beams being scheduled by one or more network nodes, a first set of beams for communication between the UE and one or more network nodes, where the first set of beams comprises one or more beams; reporting to one or more network nodes that a second rank higher than the first rank can be implemented by a second set of beams, wherein the second set of beams comprises one or more beams; and receiving a handover command from the one or more network nodes, the handover command to be scheduled on the reported second set of beams, rather than the first set of beams.

Description

Technical Field

[0001] The present disclosure relates to beam management, and in particular to UE measurement reporting for beam selection. Background Art

[0002] Any discussion of the background art throughout the specification should in no way be considered as an admission that this art is widely known or forms part of the common general knowledge in the field.

[0003] Regarding event-triggered measurement reporting for mobility, 3GPP specification 38.331 specifies the following events defined for handovers in 5G NR:

[0004] Event A1 (Service becomes better than threshold)

[0005] ●Event A2 (Service becomes worse than threshold)

[0006] ● Event A3 (neighbor cell becomes offset better than SpCell)

[0007] ●Event A4 (neighborhood becomes better than threshold)

[0008] ● Event A5 (SpCell becomes worse than threshold 1, and neighbor cell becomes better than threshold 2)

[0009] ● Event A6 (neighbor cell becomes offset better than SpCell)

[0010] Event B1 (Inter-RAT neighbor becomes better than threshold)

[0011] • Event B2 (PCell becomes worse than Threshold 1, and Inter-RAT neighbor becomes better than Threshold 2).

[0012] like Figure 1 As illustrated in , for each beam, the best beam selection using the DL L1-RSRP (reference signal received power) value does not ensure maximization of the rank, i.e., the number of layers that can be sent to the UE. If there is a high correlation between the channels with two (or even more) beams measured at the UE (and this is common, e.g. in line-of-sight LOS, single-ray or single-cluster scenarios), the UE cannot achieve a high rank due to the lack of channel diversity (uncorrelated channel components may exist only in the polarization domain). In this case, even if the gNB schedules 2 different CSI (channel state information) beams with 2 ports on each CSI beam, the UE may only see rank 1 or rank 2, but not the full possible rank 4.

[0013] Therefore, there is a need to ensure that the UE selects and obtains the maximum possible rank under the context of UE-triggered reports / events. Summary of the invention

[0014] According to a first aspect of the present disclosure, a user equipment UE is provided, the UE being configured to establish communication with one or more network nodes configured in a cell serving the UE, including:

[0015] at least one processor, and

[0016] at least one memory storing instructions that, when executed by at least one processor, cause the UE to at least:

[0017] determining a first rank associated with a first beam set, the first beam set being scheduled by one or more network nodes for communication between the UE and the one or more network nodes, wherein the first beam set comprises one or more beams;

[0018] reporting to one or more network nodes that a second rank higher than the first rank can be achieved by a second beam set, wherein the second beam set includes one or more beams; and

[0019] A handover command is received from one or more network nodes to be scheduled on the reported second beam set instead of the first beam set.

[0020] In some examples, for a beam set comprising at least two beams, the UE is configured to: determine a correlation between at least two beams included in the beam set, wherein a higher correlation between the beams indicates: a lower rank associated with the beam set.

[0021] In some examples: the first beam set includes one beam transmitted using two antenna ports, wherein the first rank corresponds to a rank indicator RI of 2; and the UE is configured to:

[0022] Instructing one or more network nodes to send a plurality of beam groups, each beam group including one or more beams for obtaining a second beam set;

[0023] receiving a plurality of beam groups from one or more network nodes;

[0024] performing measurement on beams included in the plurality of beam groups; and

[0025] determining, based on the performed measurements, a second set of beams in the plurality of beam groups that is associated with an achievable second rank that is higher than the first rank; and

[0026] and reporting the determined second beam set to one or more network nodes, wherein the reporting is triggered by the UE when the UE determines that the achievable second rank is higher than the first rank.

[0027] In some examples:

[0028] The UE is configured to: measure a reference signal received power RSRP or a signal interference plus noise SINR of each beam included in a plurality of beam groups, and the measured RSRP / SINR value of each beam is greater than or equal to a first threshold; and / or

[0029] The UE is configured to determine a rank associated with each beam group, and for each beam group, the determined rank is greater than or equal to a second threshold.

[0030] In some examples:

[0031] At least one beam group among the plurality of beam groups includes at least one beam, and the at least one beam is the one beam included in the first beam set; and / or

[0032] For at least one beam group among the plurality of beam groups, one or more beams included in the at least one beam group are all different from the one beam included in the first beam set.

[0033] In some examples, the number of one or more network nodes is less than or equal to a third threshold.

[0034] In some examples: the first beam set includes two beams respectively transmitted using one antenna port, wherein the first rank corresponds to an RI of 2; and the UE is further configured to:

[0035] indicating to the one or more network nodes that the second rank can be achieved using one or more additional beams sent from the one or more network nodes; and

[0036] receiving, from one or more network nodes, one beam transmitted using two antenna ports, or two beams respectively transmitted using one antenna port,

[0037] The second beam set includes: the first beam set, and the received one beam or the received two beams,

[0038] The second rank associated with the obtained second beam set corresponds to an RI of 4.

[0039] In some examples: the first beam set includes two beams transmitted using two antenna ports, respectively, wherein the first rank corresponds to an RI lower than 4; and the UE is further configured to:

[0040] Indicating to one or more network nodes that a second rank corresponding to an RI of 4 can be achieved by switching to a second beam set different from the first beam set; and

[0041] A second beam set is received from one or more network nodes, wherein the second beam set includes at least one beam different from two beams included in the first beam set.

[0042] In some examples, one or more beams included in the second set of beams are all different from at least one beam included in the first set of beams.

[0043] According to a second aspect of the present disclosure, a network node is provided. The network node is configured in a cell serving a user equipment UE and is configured to establish communication with the UE. The network node includes:

[0044] at least one processor, and

[0045] at least one memory storing instructions that, when executed by at least one processor, cause the network node to at least:

[0046] Scheduling a first beam set for communication with a UE, wherein the first beam set includes one or more beams, and a UE measurement value reported on the first beam set indicates: a first rank associated with the scheduled first beam set;

[0047] The UE is configured to: determine a second rank that can be achieved by a second beam set, wherein the second rank is higher than the first rank, and the second beam set includes one or more beams;

[0048] The UE is configured to: report an achievable second rank and the determined second beam set;

[0049] receiving, from the UE, an indication related to the determined second beam set; and

[0050] A handover command is sent to the UE, the handover command being used to schedule the UE on the reported second beam set instead of the first beam set.

[0051] In some examples: the first beam set includes one beam transmitted using two antenna ports, wherein the first rank corresponds to a rank indicator RI of 2; and the network node is configured to:

[0052] receiving, from the UE, an indication to send a plurality of beam groups to the UE, each beam group including one or more beams for obtaining a second beam set;

[0053] Sending multiple beam groups to the UE;

[0054] The UE is configured to: perform measurements on beams included in the plurality of beam groups to determine a second beam set associated with an achievable second rank higher than the first rank; and

[0055] An indication related to a determined second beam set is received from the UE, where the second beam set is determined by the UE in the plurality of beam groups.

[0056] In some examples: the first beam set includes two beams respectively transmitted using one antenna port, wherein the first rank corresponds to an RI of 2; and the network node is further configured to:

[0057] receiving, from the UE, an indication to add one or more beams to the first beam set to obtain an achievable second rank;

[0058] Based on the indication of adding one or more beams, a beam transmitted using two antenna ports is sent to the UE, or two beams transmitted using one antenna port are sent to the UE to obtain a second beam set, wherein the second beam set includes: the first beam set, and the transmitted beam or the transmitted two beams, wherein a second rank associated with the obtained second beam set corresponds to an RI of 4.

[0059] In some examples: the first beam set includes two beams transmitted using two antenna ports, respectively, wherein the first rank corresponds to an RI lower than 4; and the network node is further configured to:

[0060] receiving, from the UE, an indication of switching to a second beam set different from the first beam set to achieve a second rank, the second rank corresponding to an RI of 4; and

[0061] A second beam set is sent to the UE, wherein the second beam set includes: at least one beam different from two beams included in the first beam set.

[0062] In some examples, the network node is configured to configure the UE to report at least one of the following:

[0063] an achievable second rank greater than or equal to a fourth threshold, and / or lower than or equal to a fifth threshold,

[0064] other network nodes configured in the cell serving the UE,

[0065] the transmit configuration index TCI state associated with each beam obtained at the UE, and

[0066] The UE measures on the channel state information reference signal CSI-RS transmitted via each antenna port.

[0067] In some examples: the network node is configured to send to the UE a list of synchronization signals and physical broadcast channel block resource indicators SSBRI or CSI reference signal resource indicators CRI related to the beam sent from the network node to the UE, so that the UE performs measurements and determines an achievable second rank and an associated second beam set.

[0068] According to a third aspect of the present disclosure, a communication system is provided, comprising: a user equipment UE according to the first aspect and any one of its related examples; and one or more network nodes according to the second aspect and any one of its related examples, wherein the one or more network nodes are configured in a cell serving the UE.

[0069] According to a fourth aspect of the present disclosure, a method of a user equipment UE is provided, where the UE is configured to establish communication with one or more network nodes configured in a cell serving the UE, the method comprising:

[0070] determining a first rank associated with a first beam set, the first beam set being scheduled by one or more network nodes for communication between the UE and the one or more network nodes, wherein the first beam set comprises one or more beams;

[0071] reporting to one or more network nodes that a second rank higher than the first rank can be achieved by a second beam set, wherein the second beam set includes one or more beams; and

[0072] A handover command is received from one or more network nodes to be scheduled on the reported second beam set instead of the first beam set.

[0073] According to a fifth aspect of the present disclosure, a method of a network node is provided, where the network node is configured in a cell serving a user equipment UE and is configured to establish communication with the UE, the method comprising:

[0074] Scheduling a first beam set for communication with a UE, wherein the first beam set includes one or more beams, and a UE measurement value reported on the first beam set indicates: a first rank associated with the scheduled first beam set;

[0075] The UE is configured to: determine a second rank that can be achieved by a second beam set, wherein the second rank is higher than the first rank, and the second beam set includes one or more beams;

[0076] The UE is configured to: report an achievable second rank and the determined second beam set;

[0077] receiving, from the UE, an indication related to the determined second beam set; and

[0078] A handover command is sent to the UE, the handover command being used to schedule the UE on the reported second beam set instead of the first beam set.

[0079] According to a sixth aspect of the present disclosure, a computer program is provided, comprising instructions for causing an apparatus to execute the method according to the fourth aspect, or for causing an apparatus to execute the method according to the fifth aspect.

[0080] According to a seventh aspect of the present disclosure, a memory is provided, storing computer-readable instructions for causing an apparatus to execute the method according to the fourth aspect, or for causing an apparatus to execute the method according to the fifth aspect.

[0081] In addition, according to some other example embodiments, for example, a computer program product for a wireless communication device including at least one processor is provided, comprising a software code portion for executing the corresponding steps disclosed in the present disclosure when the product is run on the device. The computer program product may include a computer-readable medium storing the software code portion. In addition, the computer program product may be directly loadable into the internal memory of the computer and / or transmittable via a network by means of at least one of an upload, download, and push program.

[0082] Although some example embodiments will be described herein with particular reference to the above application, it will be appreciated that the present disclosure is not limited to this field of use and is applicable in a wider context.

[0083] It is worth noting that it is to be understood that the method according to the present disclosure relates to a method of operating a device according to the above example embodiments and variations thereof, and that corresponding statements about the device are equally applicable to the corresponding method, and vice versa, so that similar descriptions may be omitted for the sake of brevity. In addition, even if not explicitly disclosed, the above aspects may be combined in many ways. Those skilled in the art will appreciate that these combinations of aspects and features / steps are possible unless it produces a contradiction that is explicitly excluded.

[0084] Implementations of the disclosed apparatus may include, but are not limited to, the use of one or more processors, one or more application specific integrated circuits (ASICs), and / or one or more field programmable gate arrays (FPGAs). Implementations of the apparatus may also include the use of other conventional and / or custom hardware, such as software programmable processors, such as graphics processing unit (GPU) processors.

[0085] Other and further example embodiments of the present disclosure will become apparent during the course of the following discussion and with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] Example embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0087] Figure 1 schematically illustrates an example of a process that provides a UE-selected best RSRP beam but fails to maximize rank;

[0088] Figure 2 An example of a beam management process is schematically illustrated;

[0089] Figure 3 Schematically illustrates an example of event-triggered measurement reporting based on rank optimization in DL for a single TRP scenario according to an example embodiment of the present disclosure;

[0090] Figure 4 schematically illustrates an example of event-triggered measurement reporting based on rank optimization in DL for a multi-TRP scenario according to an example embodiment of the present disclosure; and

[0091] Figure 5(1) to Figure 5(2) An example of a signaling diagram for event-triggered measurement reporting based on rank optimization according to an example embodiment of the present disclosure is schematically illustrated. DETAILED DESCRIPTION

[0092] In the following, different exemplary embodiments will be described using a communication network architecture based on a 3GPP standard for a communication network (such as 5G / NR) as an example of an exemplary communication network to which the embodiments may be applied, however, the embodiments are not limited to such an architecture. It is obvious to those skilled in the art that the embodiments may also be applied to other types of communication networks in which mobile communication principles are integrated with D2D (device to device) or V2X (vehicle to everything) configurations, such as SL (side link), e.g. Wi-Fi, Worldwide Interoperability for Microwave Access (WiMAX), Personal Communications Service (PCS), Wideband Code Division Multiple Access (WCDMA), systems using ultra-wideband (UWB) technology, mobile ad hoc networks (MANET), wired access, etc. In addition, without loss of generality, the description of some examples of the embodiments is related to mobile communication networks, but the principles of the present disclosure can be extended and applied to any other type of communication network, such as a wired communication network.

[0093] The following examples and embodiments should be understood as illustrative examples only. Although the specification may refer to "one", "an" or "some" (multiple) examples or (multiple) embodiments in several places, this does not necessarily mean that each such reference is related to the same (multiple) examples or (multiple) embodiments, or that the feature only applies to a single example or embodiment. Individual features of different embodiments may also be combined to provide other embodiments. In addition, terms such as "comprising" and "including" should be understood as not limiting the described embodiments to only those features that have been mentioned; such examples and embodiments may also include features, structures, units, modules, etc. that are not specifically mentioned.

[0094] The basic system architecture of a (telecommunication) communication network including a mobile communication system to which some examples of the embodiments apply may include the architecture of one or more communication networks including (multiple) radio access network subsystems and (multiple) core networks. Such an architecture may include one or more communication network control elements or functions, access network elements, radio access network elements, access service network gateways or base transceiver stations, such as base stations (BS), access points (AP), NodeBs (NBs), eNBs or gNBs, distributed units (DUs) or centralized / central units (CUs), which control corresponding coverage areas or (multiple) cells, and one or more communication stations (such as communication elements or functions, such as user devices or terminal devices, such as user equipment (UEs)), or another device with similar functions (such as modem chipsets, chips, modules, etc.) are capable of communicating via one or more communication beams for sending several types of data in multiple access domains, via one or more channels, which may also be part of a station, element, function or application (such as a UE) capable of communicating, an element or function available in a machine-to-machine communication architecture, or attached as a separate element to such an element, function or application capable of communicating, etc. Furthermore, core network elements or network functions may be included, such as gateway network elements / functions, mobility management entities, mobile switching centers, servers, databases, etc.

[0095] The following description may provide further details of alternatives, modifications and variations: For example, in accordance with Section 3.2 of 3GPP TS 38.300 V16.6.0 (2021-06) incorporated by reference, the gNB includes, for example, a node that provides NR user plane and control plane protocol terminations to the UE and is connected to the 5GC via an NG interface.

[0096] For example, the gNB Central Unit (gNB-CU) includes logical nodes that host, for example, RRC, SDAP, and PDCP protocols of the gNB, or RRC and PDCP protocols of the en-gNB that controls the operation of one or more gNB-DUs. The gNB-CU terminates the F1 interface with the gNB-DU.

[0097] For example, the gNB distributed unit (gNB-DU) includes logical nodes such as RLC, MAC and PHY layers that host the gNB or en-gNB, and its operation is partially controlled by the gNB-CU. One gNB-DU supports one or more cells. One cell is supported by only one gNB-DU. The gNB-DU terminates the F1 interface connected to the gNB-CU.

[0098] For example, the gNB-CU control plane (gNB-CU-CP) includes a logical node that hosts the RRC and control plane parts of the PDCP protocol of a gNB-CU such as an en-gNB or gNB. The gNB-CU-CP terminates the E1 interface with the gNB-CU-UP and the F1-C interface with the gNB-DU.

[0099] For example, the gNB-CU user plane (gNB-CU-UP) includes a logical node that hosts, for example, the user plane portion of the PDCP protocol of the gNB-CU of the en-gNB, and the user plane portions of the PDCP protocol and the SDAP protocol of the gNB-CU of the gNB. For example, according to Section 3.1 of 3GPP TS 38.401 V16.6.0 (2021-07) incorporated by reference, the gNB-CU-UP terminates the E1 interface connected to the gNB-CU-CP and the F1-U interface connected to the gNB-DU.

[0100] There may be different functional splits between central and distributed units, for example, referred to as options:

[0101] Option 1 (1A Split):

[0102] ● The functional split in this option is similar to the 1A architecture in DC. RRC is located in the central unit. PDCP, RLC, MAC, physical layer and RF are all located in the distributed unit.

[0103] Option 2 (3C Split):

[0104] ● The functional split in this option is similar to the 3C architecture in DC. RRC and PDCP are located in the central unit. RLC, MAC, physical layer, and RF are all located in the distributed unit.

[0105] Option 3 (split within RLC):

[0106] ● Low RLC (part of the RLC function), MAC, physical layer and RF are located in the distributed unit. PDCP and High RLC (another part of the RLC function) are located in the central unit.

[0107] Option 4 (RLC-MAC Split):

[0108] ●MAC, physical layer and RF are located in the distributed unit. PDCP and RLC are located in the central unit.

[0109] Or, for example according to section 11 of 3GPP TR 38.801 V14.0.0 (2017-03), which is incorporated by reference.

[0110] gNB supports different protocol layers, such as Layer 1 (L1) - physical layer.

[0111] NR's Layer 2 (L2) is split into the following sublayers: Medium Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP), and Service Data Adaptation Protocol (SDAP), where, for example:

[0112] ●The physical layer provides transport channels to the MAC sublayer;

[0113] ●The MAC sublayer provides logical channels to the RLC sublayer;

[0114] ●The RLC sublayer provides RLC channels to the PDCP sublayer;

[0115] ●The PDCP sublayer provides radio bearers to the SDAP sublayer;

[0116] ●The SDAP sublayer provides QoS flows to the 5GC;

[0117] ●Comp. refers to header compression, and Segm. refers to segmentation;

[0118] ●Control channels include (BCCH, PCCH).

[0119] For example, according to Section 6 of 3GPP TS 38.300 V16.6.0 (2021-06), which is incorporated by reference, Layer 3 (L3) includes, for example, Radio Resource Control (RRC).

[0120] A RAN (Radio Access Network) node or network node (e.g., such as a gNB, base station, gNB CU or gNB DU, or part thereof) may be implemented using, for example, a device having at least one processor and / or at least one memory having computer-readable instructions (computer program) configured to support and / or provide and / or process CU and / or DU related functionality and / or features and / or at least one protocol (sub)layer of a RAN (Radio Access Network), such as Layer 2 and / or Layer 3.

[0121] The gNB CU and gNB DU parts may be, for example, co-located or physically separated. The gNB DU may even be further split into, for example, two parts, for example, one part including a processing device and one part including an antenna. The central unit (CU) may also be referred to as BBU / REC / RCC / C-RAN / V-RAN, O-RAN, or parts thereof. The distributed unit (DU) may also be referred to as RRH / RRU / RE / RU, or parts thereof. Hereinafter, in various example embodiments of the present disclosure, the CU-CP (or more generally, CU) may also be referred to as a (first) network node that supports at least one of the central unit control plane functionality or the layer 3 protocol of the radio access network; and similarly, the DU may be referred to as a (second) network node that supports at least one of the distributed unit functionality or the layer 2 protocol of the radio access network.

[0122] A gNB-DU supports one or more cells and can therefore act as a serving cell for, for example, a user equipment (UE).

[0123] User equipment (UE) may include a wireless or mobile device, a device having a radio interface that interacts with a RAN (Radio Access Network), a smartphone, an in-vehicle device, an IoT device, an M2M device, or other. Such a UE or device may include: at least one processor; and at least one memory, including computer program code, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the device to at least perform certain operations, such as, for example, an RRC connection with the RAN. The UE is, for example, configured to generate a message (e.g., including a cell ID) to be sent to the RAN via radio (e.g., to reach a serving cell and communicate with it). The UE may generate, send, and receive an RRC message including one or more RRC PDUs (Packet Data Units).

[0124] The UE may have different states (e.g. according to 3GPP TS 38.331 V16.5.0 (2021-06) sections 42.1 and 4.4, incorporated by reference).

[0125] When the RRC connection has been established, the UE is in, for example, an RRC_CONNECTED state or an RRC_INACTIVE state.

[0126] In the RRC_CONNECTED state, the UE may:

[0127] ●Store AS context;

[0128] ●Unicast data transmission between UEs;

[0129] ● monitoring a control channel associated with a shared data channel to determine whether data is scheduled for the data channel;

[0130] ●Provide channel quality and feedback information;

[0131] ●Perform neighbor cell measurements and measurement reporting.

[0132] The RRC protocol includes the following main functions:

[0133] ●RRC connection control;

[0134] ●Measurement configuration and reporting;

[0135] ● Establish / modify / publish measurement configurations (e.g. intra-frequency, inter-frequency and inter-RAT measurements);

[0136] ● Setting and releasing of measuring gap;

[0137] ●Measurement report.

[0138] The general functionality and interconnection of the described elements and functions (also depending on the actual network type) are known to a person skilled in the art and are described in the corresponding specifications, so that for the sake of brevity, a detailed description thereof may be omitted herein. However, it is to be noted that several additional network elements and signaling links may be employed to communicate with elements, functions or applications, such as communication endpoints, communication network control elements such as servers, gateways, radio network controllers, and other elements of the same or other communication networks in addition to those described in detail herein below.

[0139] The communication network architecture considered in the examples of embodiments may also be able to communicate with other networks, such as a public switched telephone network or the Internet. The communication network may also be able to support the use of cloud services for virtual network elements or their functions, wherein it should be noted that the virtual network portion of the telecommunications network may also be provided by non-cloud resources, such as an internal network, etc. It should be understood that the network elements and / or corresponding functionality of the access system, core network, etc. may be implemented by using any node, host, server, access node or entity, etc. suitable for such purpose. In general, the network functions may be implemented as network elements on dedicated hardware, software instances running on dedicated hardware, or virtualized functions instantiated on an appropriate platform (e.g., a cloud infrastructure).

[0140] In addition, network elements such as communication elements (such as UE), terminal devices, control elements or functions such as access network elements (such as base stations / BS, gNBs, radio network controllers), core network control elements or functions (such as gateway elements), or other network elements or functions described herein, as well as any other elements, functions or applications, may be implemented by software, for example, by a computer program product for a computer and / or by hardware. In order to perform its corresponding processing, the corresponding device, node, function or network element may include several components, modules, units, components, etc. (not shown) required for control, processing and / or communication / signaling functionality. Such components, modules, units and components may, for example, include one or more processors or processor units (including one or more processing parts) for executing instructions and / or programs and / or for processing data, storage or memory units or components (such as ROM, RAM, EEPROM, etc.) for storing instructions, programs and / or data to serve as working areas for processors or processing parts, etc., input or interface components for inputting data and instructions through software (such as floppy disks, CD-ROMs, EEPROMs, etc.), user interfaces (such as screens, keyboards, etc.) for providing users with monitoring and manipulation possibilities, other interfaces or components for establishing links and / or connections under the control of processor units or parts (such as wired and wireless interface components, radio interface components including, for example, antenna units, etc., components for forming radio communication parts, etc.), wherein the corresponding components forming the interface (such as radio communication parts) can also be located at remote sites (such as radio heads or radio stations, etc.). It should be noted that in this specification, a processing part should not only be regarded as representing a physical part of one or more processors, but also as a logical division of the referenced processing tasks performed by one or more processors. It should be appreciated that according to some examples, a so-called "liquid" or flexible network concept may be employed, wherein the operations and functionality of a network element, a network function, or another entity of a network may be performed in a flexible manner in different entities or functions (such as in a node, a host, or a server). In other words, the "division of labor" between the network elements, functions, or entities involved may vary from case to case.

[0141] UE-initiated beam management: In Rel-15 to Rel-18 5G NR, beam management has been specified in 3 phases of network control: Phase #1 (P1), Phase #2 (P2), and Phase #3 (P3), as described by 3GPP in TS 38.214 Section 5.1.5 (TCI and QCL framework) and Section 5.1.6 (CSI-RS reception procedure), and as Figure 2 In addition, P1, P2, and P3 are specified according to the 3GPP Rel15 study item [3GPP TR 38.802] of 5G NR.

[0142] The following beam management procedures are supported within one or more TRPs (Transmit Receive Points) of a serving cell:

[0143] ●P1: is used to enable UE measurements on different TRP Tx beams to support selection of (multiple) TRP Tx beams / UE Rx beams.

[0144] ○ For beamforming at the TRP, it typically includes intra-TRP / inter-TRP Tx beam scanning from a set of different beams. For beamforming at the UE, it typically includes UE Rx beam scanning from a set of different beams. The UE may sequentially scan its antenna / panel for each SS burst and average, for example, 3 samples.

[0145] ●P2: is used to enable UE measurements on different TRP Tx beams to possibly change (multiple) inter-TRP / intra-TRP Tx beams.

[0146] ○ Beam refinement from a possibly smaller set of beams than P1. Note that P2 can be a special case of P1. P2 can use narrower CSI beams compared to SSB beams.

[0147] ● P3: is used to enable UE measurements on the same TRP Tx beam in case the UE uses beamforming to change UE Rx beam (e.g. mmW array on UE for FR2 operation). P3 typically uses aperiodic CSI-RS with 'repeat' flag 'on' and disables UE L1-RSRP / SINR (signal-to-interference-plus-noise) reporting.

[0148] This disclosure focuses on the reporting of P2.

[0149] In TS38.214, CSI-ResourceConfig specifies what type of reference signal to send (nzp-CSI-RS-SSB, csi-IM resource). It also configures the transmission type (periodic, aperiodic, semi-persistent). The parameter reportConfigType indicates the scheduling method of the report. It can be periodic, aperiodic, and semi-persistent, as shown in the following table.

[0150] Table 1 Triggering / activation of CSI reporting for possible CSI-RS configurations

[0151]

[0152] Rel-16 enables mTRP operation with PDSCH scheduled on two beams from two TRPs simultaneously. Rel-18 is addressing the issue of indicating two TCI (Transmission Configuration Index) states simultaneously in a unified TCI framework. Within the scope of Rel-19 preparations, some use cases are being identified where the UE can benefit from initiating beam switching. The main benefits are regarding the latency of CSI L1-RSRP / L1-SINR reporting and the overhead of reporting. The obvious advantage of UE triggered reporting is that the delay between reports may be shorter over a period of time to avoid e.g. failures and that such event triggered reporting is only sent when the UE needs it (instead of increasing the periodicity of periodic measurement reports).

[0153] In view of the above, the following is proposed based on this discussion.

[0154] As a new event, the UE uses the correlation of the measured beams and therefore the maximum achievable rank of simultaneous reception / transmission to trigger a new report of the best beam pair. Therefore, if the rank provided by the currently indicated beam of PDSCH and / or PUSCH is less than another pair measured by the UE, this constitutes an event and the new pair should be reported to the network as an event-triggered beam report and a UE-initiated beam pair switch; in addition to the (transmission / reception) beam pair, the UE can also be configured to report corresponding measurement values, such as achievable rank, RSRP, SINR, etc.

[0155] In an alternative embodiment, the reporting event may be triggered by:

[0156] - In case the UE is reporting current (multiple) single-beam L1-RSRP results and the UE observes that a higher rank or data rate can be achieved via two simultaneous beams, an event is triggered to send an indication to the gNB about the higher rank in multi-beam conditions.

[0157] ○ This may be triggered at the gNB to switch reporting from single beam reporting to multi-beam / group based beam reporting.

[0158] - In case the UE is reporting the current multi-beam / group based L1-RSRP results and the UE observes that a higher rank or data rate can be achieved via only a single beam, an event is triggered to send an indication to the gNB about the higher rank under single beam condition.

[0159] ○ This may be triggered at the gNB to switch reporting from group beam based reporting to single beam based reporting.

[0160] The UE may be at least partially configured (e.g. via RRC) to perform the triggering suggested above. The configuration may include one or more of the following: the (minimum / maximum) rank that the UE should consider for the above events, or just the condition that the achievable rank of the beam pair is higher than the currently indicated rank (or previously reported rank), the number(s) to report when the event occurs, the TRP or reference signal resources to consider, the TCI (transmission configuration index) state or TCI state group to consider, etc.

[0161] The above solutions are as follows Figure 3 and Figure 4 As shown in the figure. Figure 3 In the example, a single TRP solution is illustrated. However, the solution can be extended to Figure 4 The multi-TRP scenario illustrated in FIG. 1 is even extended to UL beam selection.

[0162] The current specification focuses on X-layer (e.g. X=4) DL scheduling across two TCI states belonging to two TRPs. In this disclosure, we generalize the solution to more cases, i.e., for example, 4-layer DL scheduling can also be configured on 2 TCI states originating from the same TRP, or 4 TCI states can be indicated. All these aspects are relevant to the potential Rel-19 MIMO proposal and scope.

[0163] In summary, it is proposed according to the present disclosure that UE measurements of a higher rank than the current rank constitute an event, which then triggers UE beam reporting for the specific beam pair that produces the higher rank.

[0164] Here, the UE is able to detect a “better” beam pair than the one currently selected from the gNB (“better” here takes rank into account) because the UE is calculating the correlation between the beams, while the gNB only calculates the received power report (RSRP and / or SINR).

[0165] Digital example: See Figure 3 , e.g. the UE previously used two beam / TCI states (TCI1 and TCI2, providing the best RSRP, e.g. -80 and -82 dBm), and the UE triggers a switch to a new pair (TCI2+TCI3, even though the RSRP of TCI 3 is worse, e.g. Figure 3 -83dBm in ), as this pair allows achieving better rank.

[0166] Compared with conventional techniques (e.g. Figure 1 As shown in the figure, since a higher rank is measured, the UE triggers reporting of the beam set (SSBRI / CRI) (as opposed to the current periodic reporting for the active TCI state).

[0167] The following use case is intended for the UE to trigger TCI state addition or TCI state pair switching to maximize rank and ultimately throughput. The TCI state may come from or may correspond to one or more TRPs (TRPs may be represented by coresetPoolIndex or SRS resource set or DL ​​reference signal (resource) set in the specification, or correspond to them).

[0168] In the present disclosure, a specific rank corresponds to a rank indicator (RI) indicating the number of layers transmitted. For example, rank 1 corresponds to RI 1 indicating one layer, rank 2 corresponds to RI 2 indicating two layers, and rank 4 corresponds to RI 4 indicating 4 layers.

[0169] In the first case, the UE is currently scheduled with only 2 layers, and the UE detects that it can go up to rank 4 (i.e., 4 layers) using a specific beam pair, and reports it to the network (when configured for this). The use case is generalized to N groups of M beams, where a typical use case is N=4 and M=2, where each beam is a 2-port CSI-RS.

[0170] In the second case, the UE is also currently scheduled with only 2 layers, although these 2 layers are from two different TCI states. This would be the case for example of a single polarized antenna element at the UE, where no diversity can be achieved from polarization. Therefore, in order to achieve rank 4, the UE needs to receive 4 different TCI states simultaneously (each TCI state carries a 1-port CSI RS). This use case can be considered as an example of M=4, where each beam is a 1-port CSI-RS.

[0171] In the third case, the UE has been scheduled with 4 layers on 2 TCI states, albeit with lower throughput. The UE can detect that if a different beam pair is selected, the beams will be better de-correlated, so the maximum achievable throughput will be higher, although the individual received power level (e.g. L1-RSRP) of each of the new beams may be slightly lower than one of the beams currently used for scheduling. Based on this, the UE triggers a beam pair report to switch one or both beams to the network.

[0172] For use case 3, the UE is connected to 2 beams, but cannot achieve the maximum rank. The UE detects another pair that could actually achieve rank 4, which triggers the UE to report the new pair. The network then switches to the new pair and schedules 4-layer transmission.

[0173] Case 1: UE is scheduled with 2 layers in FR2 with 2-port CSI (i.e., 1 TCI state)

[0174] ■UE is already maximizing performance for scenarios with 2 layers;

[0175] ■UE can improve throughput by entering a scenario with 4 layers;

[0176] ■The UE may inform the network of the beam(s) to be added to the currently scheduled TCI to produce the highest rank;

[0177] ■According to this disclosure:

[0178] The gNB configures the UE to report N beam groups of M beams, where the individual RSRP / SINR levels cannot be below a threshold (e.g. a relative threshold of x dB below the current best beam) and the rank is better than y (e.g. better than rank 2);

[0179] The gNB may set a condition that, among the N beam groups, at least one group needs to contain at least one beam that is the currently indicated TCI state;

[0180] The gNB may set a condition that, among the N beam groups, at least one group may contain M beams, none of which are in the currently indicated TCI state;

[0181] The gNB may set a condition that beams belonging to N beam groups may be associated with a maximum number of k TRPs;

[0182] ●Based on the above conditions and UE measurement values, the UE can inform the network that a higher rank can be achieved by switching to a pair of beams that does not include the currently scheduled TCI (if any).

[0183] Case 2: UE is scheduled with 2 layers in FR2 with two 1-port CSIs (i.e., 2 TCI states)

[0184] ■ Note that this operation is currently only specified in mTRP, but this use case also considers sTRP extensions.

[0185] ■UE can improve throughput by entering a scenario with 4 layers. Note that this will require the gNB to indicate 4 TCI states, which may be the goal of Rel-19 for Coherent Joint Transmission (CJT).

[0186] ■According to this disclosure:

[0187] The UE informs the network whether it needs to add one 2-port CSI beam or two 1-port CSI beams to the current TCI state(s) to achieve rank 4;

[0188] ○ Based on UE indication, the gNB schedules groups of 2 or 4 simultaneous DL RSs and configures the UE with N=2 or N=4.

[0189] Case 3: UE is scheduled with 4 layers in FR2 with two 2-port CSIs (i.e., 2 TCI states)

[0190] ■ The UE is scheduled on the CSI beam reported with the highest RSRP, but the rank is still low and the throughput is not maximized, e.g. in LOS / single-ray environments.

[0191] ■ According to the present disclosure, based on the UE reporting a low rank (e.g., in 2 TCI states, reporting rank 2 instead of the expected rank 4), the UE indicates to the network that a higher rank can be achieved with a different beam pair;

[0192] ● This pair may be 2 TCI states different from the currently scheduled TCI state, in which case the network can switch the pair of beams,

[0193] ○ The gNB needs to plan the coordination and handover commands across TRP pairs in the mDCI mTRP scenario to reduce scheduling disruptions;

[0194] ● This pair may consist of one TCI state in the currently scheduled TCI state and the new TCI state, in which case the network only needs to perform a TCI state switch,

[0195] ○ The UE may report a pair with CRI and reportquantity, or

[0196] ○ The UE can only report the new TCI to be added and point to the TCI index that needs to be retained (among the 2 TCI indexes currently scheduled);

[0197] ○ Coordinate single beam switching while preserving DL scheduling on the remaining beams (mDCI and DL throughput optimization are not interrupted).

[0198] Additionally, the gNB can provide the UE with a list of SSBRI / CRIs where the UE can measure the correlation and trigger a beam pair switch if a higher rank is detected. Thus, the search for the UE is reduced and the gNB still controls the beams for which the UE can trigger a beam pair switch.

[0199] Figure 5(1) to Figure 5(2) Examples of signaling diagrams for event-triggered measurement reporting based on rank optimization are schematically illustrated, in particular for the above three use cases.

[0200] As shown in FIG5(1), for all the above three use cases, the present disclosure proposes:

[0201] Step 501: UE establishes RRC connection with gNB; and

[0202] Step 502: The gNB sends an RRC configuration for UE CSI reporting to the UE, wherein the RRC configuration is used to indicate N groups of M beams to the UE. Optionally, the RRC configuration includes an RSRP / SINR threshold for each of the M beams and a minimum rank for each of the groups. Optionally, the RRC configuration includes a presence condition (e.g., in an active / indication list).

[0203] Specifically, for the first use case above, as shown in FIG5(1), according to the present disclosure, the following is proposed:

[0204] Step 503: The gNB performs 2-layer PDSCH transmission and sends 1 beam with 2-port CSI-RS to the UE.

[0205] Step 504: UE reports rank 2 as part of CSI L1 report;

[0206] Step 505: The UE detects additional TCI states, DL-RS, SSBRI / CRI, and if scheduled simultaneously with the current TCI state, provides rank 4. Alternatively, the UE detects a TCI state pair that does not include the current TCI state;

[0207] Step 506: The above events of possibly higher rank measured by the UE trigger the UE report of the candidate beam;

[0208] Step 507: The UE indicates the candidate beams of rank 4 to the gNB as part of the CSI report; and

[0209] Step 508: The gNB selects a pair of 2-port CSI-RS for 4-layer PSDCH transmission.

[0210] Specifically, for the second use case above, as shown in FIG5(1), the present disclosure proposes:

[0211] Step 509: The gNB performs 2-layer PDSCH transmission and sends 2 beams with 1-port CSI-RS to the UE.

[0212] Step 510: UE reports rank 2 as part of CSI L1 reporting;

[0213] Step 511: The UE detects that one 2-port CSI-RS or two 1-port CSI-RS are needed to achieve rank 4;

[0214] Step 512: The UE detects DL-RS, SSBRI / CRI of (multiple) additional TCI states, and provides rank 4 if it is scheduled simultaneously with the current TCI state;

[0215] Step 513: The above events of possibly higher rank measured by the UE trigger the UE report of the candidate beam;

[0216] Step 514: The UE indicates the candidate beams to the gNB; and

[0217] Step 515: The gNB selects four 1-port CSI-RS for 4-layer PSDCH transmission.

[0218] Specifically, for the third use case above, as shown in FIG5(2), the present disclosure proposes:

[0219] Step 516: The gNB sends a reference signal and two beams with a two-port CSI-RS to the UE.

[0220] Step 517: The UE performs rank 2 reporting on the measured CSI-RS resource pair;

[0221] Step 518: The UE detects different pairs of TCI states, which may or may not include one of the TCI states in the currently indicated TCI state, and provides rank 4;

[0222] Step 519: The above events of possibly higher rank measured by the UE trigger the UE report of the candidate beam;

[0223] Step 520: The UE indicates the DL-RS, SSBRI / CRI of the candidate beam / pair to the gNB.

[0224] Step 521: The gNB selects a pair of 2-port CSI-RS for 4-layer PSDCH transmission.

[0225] Step 522: The gNB adds the indicated beam / pair to the list of active TCI states if it does not already exist; and

[0226] Step 523: gNB performs 4-layer PDSCH transmission.

[0227] It should be noted that although in the example embodiments illustrated above (refer to the accompanying drawings), the messages passed / exchanged between network components / elements may appear to have specific / clear names, depending on various implementations (e.g., underline technology), these messages may have different names and / or be passed / exchanged in different forms / formats, as can be understood and appreciated by technicians.

[0228] According to some example embodiments, corresponding methods suitable for being performed by the above-mentioned apparatus (network element / component), such as UE, CU, DU, etc., are also provided.

[0229] However, it should be noted that the above-mentioned device (equipment) features correspond to corresponding method features, but for the sake of brevity, such method features may not be explicitly described. The disclosure of this document is considered to extend to such method features as well. In particular, the present disclosure is understood to relate to methods of operating the above-mentioned devices and / or providing and / or arranging corresponding elements of these devices.

[0230] In addition, according to some other example embodiments, a corresponding device (for example, implementing the above-mentioned UE, CU, DU, etc.) is also provided, which includes at least one processing circuit system and at least one memory for storing instructions executed by the processing circuit system, wherein the at least one memory and the instructions are configured to, together with the at least one processing circuit system, enable the corresponding device to at least perform the above-mentioned corresponding steps.

[0231] However, in some other example embodiments, a corresponding apparatus (eg, implementing the above-mentioned UE, CU, DU, etc.) is provided, which includes corresponding components configured to at least perform the above-mentioned corresponding steps.

[0232] It should be noted that the examples of the embodiments of the present disclosure are applicable to a variety of different network configurations. In other words, the examples shown in the above figures used as the basis for the examples discussed above are merely illustrative and do not limit the present disclosure in any way. That is, based on the defined principles, additional other existing and proposed new functionality available in the corresponding operating environment can be used in conjunction with the examples of the embodiments of the present disclosure.

[0233] It should also be noted that the disclosed example embodiments can be implemented in many ways using hardware and / or software configurations. For example, the disclosed embodiments can be implemented using dedicated hardware and / or hardware associated with software executable thereon. The components and / or elements in the accompanying drawings are examples only and do not limit the scope of use or functionality of any hardware, software combined with hardware, firmware, embedded logic components, or a combination of two or more such components that implement a specific embodiment of the present disclosure.

[0234] It should be further noted that the description and the accompanying drawings illustrate only the principles of the present disclosure. Those skilled in the art will be able to realize various arrangements that implement the principles of the present disclosure and are included in its spirit and scope, although not explicitly described or shown herein. In addition, all examples and embodiments summarized in this disclosure are primarily intended to be explicitly for illustrative purposes only, to help the reader understand the principles of the proposed method. In addition, all statements providing the principles, aspects and embodiments of the present disclosure and their specific examples herein are intended to cover their equivalents.

[0235] List of abbreviations:

[0236] UE – User Equipment

[0237] RSRP – Reference Signal Received Power

[0238] CSI – Channel State Information

[0239] TCI – Transmit Configuration Index

[0240] DL RS – Downlink Reference Signal

[0241] PUCCH – Physical Uplink Control Channel

[0242] PUSCH – Physical Uplink Shared Channel

[0243] SRS – Sounding Reference Signal

[0244] RRC – Radio Resource Control

[0245] MAC CE – Media Access Control Element

[0246] TRP – Transmit Receive Point

[0247] PCI – Physical Cell Id

[0248] SSB – Synchronization Signal Block

[0249] SSBRI – Synchronization Signal and Physical Broadcast Channel Block Resource Indicator

Claims

1. A user equipment UE, configured to establish communication with one or more network nodes configured in a cell serving the UE, comprising: at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the UE to at least: determining a first rank associated with a first beam set scheduled by the one or more network nodes for the communication between the UE and the one or more network nodes, wherein the first beam set comprises one or more beams; reporting to the one or more network nodes that a second rank higher than the first rank can be achieved by a second beam set, wherein the second beam set includes one or more beams; as well as A handover command is received from the one or more network nodes, the handover command being scheduled on the reported second beam set instead of the first beam set.

2. The UE according to claim 1, wherein: For a beam set including at least two beams, the UE is configured to: determine a correlation between the at least two beams included in the beam set, wherein a higher correlation between the beams indicates: a lower rank associated with the beam set.

3. The UE according to claim 1 or 2, wherein: The first beam set includes one beam transmitted using two antenna ports, wherein the first rank corresponds to a rank indicator RI of 2; and The UE is configured to: Instructing the one or more network nodes to send a plurality of beam groups, each beam group comprising one or more beams for obtaining the second beam set; receiving the plurality of beam groups from the one or more network nodes; performing measurement on the beams included in the plurality of beam groups; and determining, based on the performed measurements, among the plurality of beam groups, the second beam set associated with the achievable second rank higher than the first rank; and and reporting the determined second beam set to the one or more network nodes, wherein the reporting is triggered by the UE when the UE determines that the achievable second rank is higher than the first rank.

4. The UE according to claim 3, wherein: The UE is configured to: measure a reference signal received power RSRP or a signal interference plus noise ratio SINR of each beam included in the multiple beam groups, and the measured RSRP / SINR value of each beam is greater than or equal to a first threshold; and / or The UE is configured to determine a rank associated with each beam group, and for each beam group, the determined rank is greater than or equal to a second threshold.

5. The UE according to claim 3 or 4, wherein: At least one beam group among the plurality of beam groups includes at least one beam, and the at least one beam is the one beam included in the first beam set; and / or For at least one beam group among the plurality of beam groups, the one or more beams included in the at least one beam group are all different from the one beam included in the first beam set. 6 . The UE according to claim 3 , wherein the number of the one or more network nodes is less than or equal to a third threshold.

7. The UE according to any one of claims 1 to 6, wherein: The first beam set includes two beams respectively transmitted using one antenna port, wherein the first rank corresponds to an RI of 2; and The UE is further configured to: indicating to the one or more network nodes that the second rank can be achieved using one or more additional beams sent from the one or more network nodes; and receiving, from the one or more network nodes, one beam transmitted using two antenna ports, or two beams respectively transmitted using one antenna port, The second beam set includes: the first beam set, and the one received beam or the two received beams, The second rank associated with the obtained second beam set corresponds to an RI of 4.

8. The UE according to any one of claims 1 to 7, wherein: The first beam set includes two beams respectively transmitted using two antenna ports, wherein the first rank corresponds to an RI lower than 4; and The UE is further configured to: indicating to the one or more network nodes that the second rank corresponding to the RI of 4 can be achieved by switching to the second beam set different from the first beam set; as well as The second beam set is received from the one or more network nodes, wherein the second beam set includes at least one beam different from the two beams included in the first beam set. 9 . The UE according to claim 1 , wherein the one or more beams included in the second beam set are all different from at least one beam included in the first beam set.

10. A network node, the network node being configured in a cell serving a user equipment UE and configured to establish communication with the UE, the network node comprising: at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the network node to at least: Scheduling a first beam set for the communication with the UE, wherein the first beam set includes one or more beams, and UE measurement values ​​reported on the first beam set indicate: a first rank associated with the scheduled first beam set; The UE is configured to: determine a second rank that can be achieved by a second beam set, wherein the second rank is higher than the first rank, and the second beam set includes one or more beams; Configuring the UE to: report the achievable second rank and the determined second beam set; receiving, from the UE, an indication related to the determined second beam set; as well as A handover command is sent to the UE, wherein the handover command is used to schedule the UE on the reported second beam set instead of the first beam set.

11. The network node according to claim 10, wherein: The first beam set includes one beam transmitted using two antenna ports, wherein the first rank corresponds to a rank indicator RI of 2; and The network node is configured to: receiving, from the UE, an indication to transmit a plurality of beam groups to the UE, each beam group comprising one or more beams for obtaining the second beam set; Sending the multiple beam groups to the UE; configuring the UE to: perform measurements on the beams included in the plurality of beam groups to determine the second beam set associated with the achievable second rank higher than the first rank; and An indication related to the determined second beam set is received from the UE, where the second beam set is determined by the UE among the plurality of beam groups.

12. The network node according to claim 10, wherein: The first beam set includes two beams respectively transmitted using one antenna port, wherein the first rank corresponds to an RI of 2; and The network node is further configured to: receiving, from the UE, an indication of adding one or more beams to the first beam set to obtain the achievable second rank; Based on the indication of adding one or more beams, one beam transmitted using two antenna ports is sent to the UE, or two beams transmitted using one antenna port are sent to the UE to obtain the second beam set, wherein the second beam set includes: the first beam set, and the one beam transmitted or the two beams transmitted, wherein the second rank associated with the obtained second beam set corresponds to an RI of 4.

13. The network node according to claim 10, wherein: The first beam set includes two beams respectively transmitted using two antenna ports, wherein the first rank corresponds to an RI lower than 4; and The network node is further configured to: receiving, from the UE, an indication of switching to a second beam set different from the first beam set to implement a second rank, the second rank corresponding to an RI of 4; as well as The second beam set is sent to the UE, wherein the second beam set includes: at least one beam different from the two beams included in the first beam set.

14. The network node according to any one of claims 10 to 13, wherein the network node is configured to: configure the UE to report at least one of the following: the achievable second rank being greater than or equal to a fourth threshold, and / or lower than or equal to a fifth threshold, other network nodes configured in the cell serving the UE, a transmit configuration index (TCI) state associated with each beam obtained at the UE, and The UE measures on the channel state information reference signal CSI-RS transmitted via each antenna port.

15. The network node according to any one of claims 10 to 14, wherein The network node is configured to send to the UE a list of synchronization signals and physical broadcast channel block resource indicators SSBRI or CSI reference signal resource indicators CRI related to the beam sent from the network node to the UE, so that the UE performs measurement and determines the achievable second rank and the associated second beam set.

16. A communication system comprising: A user equipment UE according to any one of claims 1 to 9; as well as One or more network nodes according to any one of claims 10 to 15, The one or more network nodes are configured in a cell serving the UE.

17. A method for a user equipment (UE), wherein the UE is configured to establish communication with one or more network nodes configured in a cell serving the UE, the method comprising: determining a first rank associated with a first beam set scheduled by the one or more network nodes for the communication between the UE and the one or more network nodes, wherein the first beam set comprises one or more beams; reporting to the one or more network nodes that a second rank higher than the first rank can be achieved by a second beam set, wherein the second beam set includes one or more beams; as well as A handover command is received from the one or more network nodes, the handover command being scheduled on the reported second beam set instead of the first beam set.

18. A method of a network node, the network node being configured in a cell serving a user equipment UE and configured to establish communication with the UE, the method comprising: Scheduling a first beam set for the communication with the UE, wherein the first beam set includes one or more beams, and UE measurement values ​​reported on the first beam set indicate: a first rank associated with the scheduled first beam set; The UE is configured to: determine a second rank that can be achieved by a second beam set, wherein the second rank is higher than the first rank, and the second beam set includes one or more beams; Configuring the UE to: report the achievable second rank and the determined second beam set; receiving, from the UE, an indication related to the determined second beam set; as well as A handover command is sent to the UE, wherein the handover command is used to schedule the UE on the reported second beam set instead of the first beam set.

19. A computer program product comprising instructions for causing an apparatus to perform the method according to any one of claims 1 to 9, or the method according to any one of claims 10 to 15.

20. A memory storing computer-readable instructions, wherein the computer-readable instructions are used to cause an apparatus to execute the method according to any one of claims 1 to 9, or the method according to any one of claims 10 to 15.

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