Method and system for fast moving cell measurement and measurement reporting based on lower layer signaling

Abstract

The present disclosure relates to UE measurement and measurement reporting of serving cells, and configuration for cell measurement and reporting to enable fast serving cell change during UE mobility within lower network layers, such as layer-1 or layer-2 of a wireless communication protocol stack. The present disclosure further relates to signaling procedures associated with fast serving cell change for a UE triggered by the network based on cell measurement and reporting, and various lower layer configurations and operations for enabling actual fast serving cell change at and for the UE.

Description

Technical Field

[0001] This disclosure generally relates to the mobility of wireless terminal devices, and more particularly to a rapid serving cell change process triggered by Layer-1 or Layer-2 signaling. Background Technology

[0002] In a cellular radio access network, each cell can be associated with a coverage area. The coverage areas of multiple cells collectively provide radio services to user equipment (UE). As a UE moves, its connectable cells may change, and consequently, the UE's active radio data connections may change from one cell to another. Such cell changes or handovers can involve complex signaling and operations at various layers of the wireless communication network protocol stack for both the UE and the network. For the signaling and operations of cell changes, it is generally preferable to minimize communication overhead and maximize communication efficiency and speed. Summary of the Invention

[0003] This disclosure generally relates to UE mobility in a radio access network, particularly UE measurements and measurement reporting for a serving cell, and the configuration of cell measurements and reporting to enable rapid serving cell changes during UE movement within lower network layers (such as layer-1 or layer-2 of the wireless communication protocol stack). This disclosure further relates to signaling procedures associated with rapid serving cell changes for a UE, triggered by the network based on cell measurements and reporting, and various lower-layer configurations and operations for implementing and performing the actual rapid serving cell changes for the UE.

[0004] In some implementations, a method for preparing a serving cell change process, performed by a wireless device, is disclosed. This method may include receiving cell measurement and measurement reporting configuration from a wireless communication node; performing cell measurements based on the cell measurement and measurement reporting configuration to generate a cell measurement report associated with the cell measurements; and sending the cell measurement report in a cell measurement reporting message, which includes layer-1 or layer-2 control messages, according to the cell measurement and measurement reporting configuration.

[0005] In the above implementation, layer-1 includes a physical (PHY) layer, and layer-2 includes at least one of the following: a media access control (MAC) layer, a radio link control (RLC) layer, or a packet data convergence protocol (PDCP) layer.

[0006] In any of the above implementations, sending a cell measurement report may include reporting cell measurements via a Layer-1 Uplink Control Information (UCI) message or a Layer-2 MAC Control Unit (MAC CE) message.

[0007] In any of the above implementations, the cell measurement report may include: measurement results for the source serving cell of the wireless device and at least one or more neighboring cells of the source serving cell.

[0008] In any of the above implementations, the method may further include: identifying one or more suitable neighboring serving cells from a set of candidate neighboring cells of the source serving cell for the wireless device, based on the performed cell measurement, wherein the cell measurement report includes physical cell information of one or more suitable neighboring cells.

[0009] In any of the above implementations, the cell measurement report may further include beam information for one or more suitable neighboring cells, and the beam information is provided to indicate one or more recommended beams from one or more suitable neighboring cells used for the service cell change process.

[0010] In any of the above implementations, the cell measurement and measurement reporting configuration can indicate to the wireless device the triggering event conditions for sending cell measurement reports.

[0011] In any of the above implementations, the triggering event conditions for sending a cell measurement report may include at least one of the following set of triggering event conditions: a first result of the cell measurement indicates that the source serving cell of the radio device is continuously at or below a first threshold measurement level during a first pre-configured measurement time period; a second result of the cell measurement indicates that at least one neighboring cell of the source serving cell of the radio device is continuously at or above a second threshold measurement level during a second pre-configured measurement time period; or the difference measurement result between the first result and the second result is continuously at or above a cell measurement gap threshold level.

[0012] In any of the above implementations, the first threshold measurement level may include: the sum of the offset of a first pre-configured baseline threshold level and a first configurable tolerance threshold level.

[0013] In any of the above implementations, the second threshold measurement level may include the sum of the offset of a second pre-configured baseline threshold level and a second configurable tolerance threshold level.

[0014] In any of the above implementations, the cell measurement gap threshold level may include the sum of a pre-configured baseline gap threshold level and a configurable tolerance gap threshold level offset.

[0015] In any of the above implementations, the first pre-configured measurement time period may include: N consecutive measurement opportunities on the source serving cell for the wireless device, where N is a pre-configured positive integer.

[0016] In any of the above implementations, the second pre-configured measurement time period may include M consecutive measurement opportunities performed on at least one neighboring cell of the source serving cell of the wireless device, where M is a pre-configured positive integer.

[0017] In any of the above implementations, the first result or the second result may include at least one of the following: reference signal received power (RSRP), signal-to-interference and noise ratio (SINR), or reference signal received quality (RSRQ).

[0018] In any of the above implementations, each of the first result and the second result may respectively include cell-level measurement results or beam-level measurement results associated with the source serving cell of the wireless device and at least one neighboring cell of the source serving cell.

[0019] In any of the above implementations, the cell-level measurement results of the serving cell can be derived from measurements of multiple beams associated with the serving cell.

[0020] In any of the above implementations, beam-level measurement results may include measurement results associated with the following: a predetermined number of optimal beams with respect to the source serving cell of the wireless device or at least one suitable neighboring cell of the source serving cell.

[0021] In any of the above implementations, the first result may include the measurement results of a first merged N consecutive cell measurements performed by the wireless device on the source serving cell, where N is a pre-configured positive integer. The second measurement result includes the measurement results of a second merged N consecutive cell measurements performed on at least one neighboring cell of the source serving cell. The triggering event condition for sending the cell measurement report includes: sending the cell measurement report when the difference between the measurement results of the first merged N consecutive cell measurements and the measurement results of the second merged N consecutive cell measurements is at or exceeds a cell measurement gap threshold level.

[0022] In any of the above implementations, sending a cell measurement report in a cell measurement reporting message may include, when at least one of a set of triggering event conditions is met: sending a MAC CE message containing the cell measurement report to the wireless communication node; or triggering the wireless device to send the cell measurement reporting message as Layer-1 uplink control information (UCI) to the wireless communication node.

[0023] In any of the above implementations, the applicable triggering event conditions in a set of triggering event conditions may be configured for each serving cell or for a list of candidate serving cells.

[0024] In any of the above implementations, the first and second neighboring cells of at least one neighboring cell of the source serving cell can be independently configured with different triggering event conditions from a set of triggering event conditions.

[0025] In any of the above implementations, a set of triggering event conditions may further include the wireless device detecting a beam failure in the source serving cell and fewer than P suitable beams of the source serving cell being identifiable; or the wireless device detecting a radio link failure with respect to the source serving cell.

[0026] In some other implementations, a wireless device including a processor and memory is disclosed. The processor can be configured to read computer code from memory to implement any of the methods described above.

[0027] In some other implementations, a computer program product is disclosed, including a non-transitory computer-readable program medium on which computer code is stored. When the computer code is executed by a processor, the processor may implement any of the methods described above.

[0028] Other aspects and alternatives to the above embodiments and their implementations will be described in more detail in the following drawings, description and claims. Attached Figure Description

[0029] Figure 1 This section describes an example wireless communication network that includes a wireless access network, a core network, and a data network.

[0030] Figure 2 An example radio access network is described, which includes multiple mobile stations or UEs communicating with each other via an over-the-air radio communication interface and radio access network nodes.

[0031] Figure 3 An example communication protocol stack is shown in a wireless access network node or wireless terminal device that includes various network layers.

[0032] Figure 4 This paper describes a split architecture for separating a radio access network node into a central unit (CU) and one or more distributed units (DU).

[0033] Figure 5 Example signaling and operational flowcharts are shown for the preparation phase of a lower-layer rapid serving cell change.

[0034] Figure 6 Example signaling and operation flowcharts are shown for the execution phase of a lower-layer rapid serving cell change. Detailed Implementation

[0035] The techniques and examples of the implementations and / or embodiments described in this disclosure can be used to facilitate the allocation, configuration, and signaling of air radio resources in a radio access network. The term "example" is used to mean "one example" and, unless otherwise stated, does not imply an ideal or preferred example, implementation, or embodiment. Section headings used in this disclosure are for ease of understanding of the disclosed implementations and are not intended to limit the techniques disclosed in each section to the corresponding section. The disclosed implementations may be further embodied in various different forms, and therefore, the scope of this disclosure or the claimed subject matter is intended to be construed as not being limited to any of the embodiments described below. Various implementations may be embodied as methods, apparatuses, components, systems, or non-transitory computer-readable media. Thus, embodiments of this disclosure, for example, may take the form of hardware, software, firmware, or any combination thereof.

[0036] This disclosure relates to UE measurements and measurement reporting of the serving cell, and the configurations used for cell measurements and reporting to enable rapid serving cell changes during UE movement within a lower network layer (e.g., layer-1 or layer-2 of the wireless communication protocol stack). This disclosure further relates to signaling procedures associated with rapid serving cell changes for the UE triggered by the network based on cell measurements and reporting, and various lower-layer configurations and operations for implementing and for the actual rapid serving cell change at the UE.

[0037] Wireless Network Overview

[0038] like Figure 1 The example wireless communication network shown in Figure 100 may include user equipment (UE) 110, 111, and 112, operator network 102, various service applications 140, and other data networks 150. For example, operator network 102 may include access networks 120 and 121 and core network 130. Operator network 102 may be configured to transmit voice, data, and other information (collectively referred to as data services) between UEs 110, 111, and 112, between UEs and service applications 140, or between UEs and other data networks 150. Access networks 120 and 121 may be configured as various radio access network nodes (WANNs, alternatively referred to as base stations) to interact with UEs on one side of a communication session and with core network 130 on the other side. Core network 130 may include various network nodes configured to control communication sessions and perform network access management and service routing. Service applications 140 may be hosted by various application servers deployed outside of core network 130 but connected to core network 130. Similarly, other data networks 150 can also be connected to the core network 130.

[0039] exist Figure 1In the wireless communication network of 100, UEs can communicate with each other via a radio access network. For example, UEs 110 and 112 can connect to and communicate via the same access network 120. UEs can communicate with each other via both the access network and the core network. For example, UE 110 can be connected to access network 120, while UE 111 can be connected to access network 121; therefore, UEs 110 and UE 111 can communicate with each other via access networks 120 and 121 and the core network 130. UEs can further communicate with serving application 140 and data network 150 via the core network 130. Furthermore, as shown in 113, UEs can communicate directly with each other via sidelink communication.

[0040] Figure 2 A further example system diagram of a wireless access network 120 is shown, which includes a WANN 202 providing services to UEs 110 and 112 via an air interface 204. The radio transmission resources of the air interface 204 include a combination of frequency, time, and / or spatial resources. Each of UEs 110 and 112 can be a mobile or fixed terminal device equipped with a mobile access unit (such as a SIM / USIM module) for accessing the wireless communication network 100. Both UEs 110 and 112 can be implemented as terminal devices, including but not limited to mobile phones, smartphones, tablets, laptops, vehicle-mounted communication devices, roadside communication devices, sensor devices, smart appliances (such as televisions, refrigerators, and ovens), or other devices capable of wireless communication over the network. Figure 2 As shown, each UE (such as UE 112) may include transceiver circuitry 206 coupled to one or more antennas 208 to enable wireless communication with WANN 120 or another UE (such as UE 110). Transceiver circuitry 206 may also be coupled to processor 210, which may also be coupled to memory 212 or other storage devices. Memory 212 may be transient or non-transient and may store computer instructions or code therein that, when read and executed by processor 210, cause processor 210 to implement the various methods described herein.

[0041] Similarly, WANN 120 may include a base station or other wireless network access point capable of wirelessly communicating with one or more UEs via air interface 204 and with core network 130. For example, but not limited to, WANN 120 may be implemented as a 2G base station, 3G nodeB, LTE eNB, 4G LTE base station, 5G NR base station, 5G central unit base station, or 5G distributed unit base station. Each type of these WANNs may be configured to perform a corresponding set of wireless network functions. WANN 202 may include transceiver circuitry 214 coupled to one or more antennas 216, which may include various forms of antenna towers 218 to enable wireless communication with UEs 110 and 112. Transceiver circuitry 214 may be coupled to one or more processors 220, which may be further coupled to memory 222 or other storage devices. The memory 222 may be transient or non-transient and may store instructions or code therein, which, when read and executed by one or more processors 220, cause one or more processors 220 to perform the various functions of the WANN 120 described herein.

[0042] Such as Figure 2 In the example wireless access network, data packets can be transmitted as Protocol Data Units (PDUs). The data contained within can be encapsulated as PDUs at various network layers wrapped in nested and / or layered protocol headers. Once a connection is established between the transmitting and receiving ends (e.g., a Radio Link Control (RRC) connection), the PDUs can communicate between the transmitting device or receiving end (these terms are used interchangeably) and the receiving device or receiving end (these terms are also used interchangeably). Any transmitting or receiving device can be a wireless terminal device, such as... Figure 2 Devices 110 and 120 in the diagram may be wireless access network nodes, such as... Figure 2 Node 202 in the diagram. For bidirectional communication, each device can be both a sending device and a receiving device.

[0043] like Figure 3 As shown, for example, WANN 120 may further include multiple individual access network nodes in the form of a central unit (CU) 302 and at least one distributed unit (DU) 304 and 306. CU 122 may be connected to DU1 304 and DU2 306 via various F1 interfaces. For example, the F1 interfaces may further include F1-C and F1-U interfaces, which can be used to transmit control plane data and user plane data, respectively. UE can connect to core network 130 via radio interface through WANN 120.

[0044] Each DU can provide service to a UE via one or more cells. Each cell is associated with a coverage area. These cells are alternatively referred to as serving cells. Coverage areas between cells may partially overlap. Each UE can actively communicate with at least one cell and may potentially connect to or connect to more than one cell. Figure 3 In the example, UE1, UE2, and UE3 may be served by cell 1 320 of DU1, while UE4 and UE5 may be served by cell 2 330 of DU1. In some implementations, a UE may be served by two or more cells simultaneously. Each UE may be mobile, and the signal strength and quality from each cell at the UE may depend on the UE's location. In some implementations, the CU may be the gNB Central Unit (gNB-CU), and the DU may be the gNB Distributed Unit (gNB-DU). Although the various implementations described below are provided in the context of 5G cellular wireless networks, the basic principles described herein are applicable to other types of radio access networks, including but not limited to other generations of cellular networks and Wi-Fi, Bluetooth, ZigBee, and WiMax networks.

[0045] In some example implementations, Figure 3 The cells shown may be alternatively referred to as serving cells. Serving cells may be grouped into serving cell groups (CGs). Serving cell groups may be primary CGs (MCGs) or secondary CGs (SCGs). Within each type of cell group, there may be one primary cell and one or more secondary cells. For example, the primary cell in an MCG may be referred to as PCell, while the primary cell in an SCG may be referred to as PScell. Secondary cells in either an MCG or an SCG may be referred to as SCell. The primary cells, including both PCell and PScell, may be collectively referred to as SpCell. All of these cells may be referred to as serving cells or multiple cells. Unless otherwise specified, the terms "cell" and "serving cell" are used interchangeably. The term "serving cell" may refer to a cell that is currently serving, will serve, or may serve a UE. In other words, a "serving cell" may not currently be providing service to a UE. While the various embodiments described below may sometimes refer to one of the types of serving cells described above, the basic principles apply to all types of serving cells within both types of serving cell groups.

[0046] Figure 4 This further explains in Figures 1-3 A simplified view of the various network layers involved in transmitting a user plane PDU from transmitting device 402 to receiving device 404 in an example wireless access network. Figure 4 It is not intended to include all the basic device components or network layers used to process the transmission of PDUs. Figure 4This describes how data encapsulated by the upper network layer 420 at the transmitting device 402 can be sent to the corresponding upper layer 430 (such as the Radio Resource Control or RRC layer) at the access device 304 via the following: the packet data convergence protocol layer (PDCP layer) of the transmitting device. Figure 4 The network entities in each of these layers (not shown) include the Radio Link Control (RLC) layer 422, the Physical (PHY) layer of the transmitting and receiving devices, the radio interface (as shown in 406), and the Media Access Control (MAC) layer 434 and RLC layer 432 of the receiving device. Each network entity in each of these layers can be configured to handle the transmission and retransmission of PDUs.

[0047] exist Figure 4 In the middle, the upper layer 420 can be referred to as layer-3 or L3, while the intermediate layers are such as RLC layers and / or MAC layers and / or PDCP layers ( Figure 4 (Not shown in the diagram) can be collectively referred to as Layer-2 or L2, and the term Layer-1 is used to refer to layers such as the physical layer and radio interface associated layers. In some cases, the term "lower layer" can be used to refer to the set of L1 and L2, while the term "higher layer" can be used to refer to Layer-3. The term "lower layer" can be used to refer to layers in L1, L2, and L3 that are below the current reference layer. Control signaling can be initiated and triggered in each of the layers L1 to L3 and in the respective network layers within them. These signaling messages can be encapsulated and concatenated into lower layer packets and transmitted via allocated control or data air radio resources and interfaces. The term "layer" generally includes various corresponding entities. For example, the MAC layer includes corresponding MAC entities that can be created. For example, Layer-1 includes PHY entities. As another example, Layer-2 includes MAC layer / entities, RLC layer / entities, and / or PDCP layer / entities.

[0048] Back Figure 3 The various functions of a wireless access network node can be separated between the CU and DU. For example, the DU can host lower layers including L2 and L1, such as RLC, MAC, and PHY (physical) layers, while the CU can host higher layers of the network, such as L3.

[0049] General UE mobility and serving cell changes

[0050] When a UE moves between the coverage areas of various cells, the signal strength and quality from those cells change. The UE can be configured to measure and monitor cell signal strength and quality. The parameters associated with performing these measurements can be configured by the network. In some cases, signal differences between cells may require a change of serving cell from a source serving cell (alternately referred to as the original serving cell) to a target serving cell (alternately referred to as serving cell handover, PCell and SCell role change, or serving cell handover) to proactively provide service to the UE. The source serving cell and the target (serving) cell can be served by the same DU, or by different DUs associated with the same CU, or by different CUs. Therefore, a serving cell change can be intra-DU (when changing cells within one or more cells served by the same DU) or inter-DU (when changing from a source cell served by one DU to a target cell served by another DU). An inter-DU serving cell change can be intra-CU (when changing from a source cell to a target cell served by the same CU) or inter-CU (when changing from a source cell served by one CU to a target cell served by another CU). These cell changes represent different levels of cell changes and may involve various levels of service cell configuration changes, resets, and handover processes.

[0051] In some implementations, serving cell handover can be triggered as a result of L3 measurements, regardless of whether the source and target serving cells are inter-CU or intra-CU, and can be achieved via synchronized Radio Resource Control (RRC) signaling. For example, RRC signaling can be used to implement changes to SpCells (from one SpCell to another) (the SpCell can be a PCCell or PSCell), and, where applicable, to release / add SCells. Such SpCell change processes initiated via RRC reconfiguration typically result in lengthy interruptions in user plane data communications / streams, significant delays in updating user plane data transmissions, and are generally associated with considerable RRC signaling overhead.

[0052] This high-latency, RRC-based reconfiguration serving cell change process, moving from one serving cell to another, can sometimes be difficult to avoid, especially when the change involves source and target serving cells served by different CUs (inter-CU serving cell change). However, in most cases, handover may occur from one cell to another served by the same DU (intra-DU serving cell change), or between cells served by different DUs within the same CU (inter-DU, but intra-CU). In these cases, the UE serving cell change may not require any changes to the serving CU hosting the L3 entity. In this scenario, UE movement only involves non-L3 lower layers of the communication protocol stack residing in the DU, including, for example, L1 and / or L2 layers, such as the RLC / MAC / PHY layers, etc. Figure 3 As shown. In this scenario, there is no need to require the UE to perform a serving cell change procedure based on L3 signaling.

[0053] Serving cell change processes implemented using only L1 and / or L2 signaling are fast and flexible, have minimal impact / interference on user plane data streams, and help reduce handover latency and signaling overhead. This L1 / L2-based serving cell change can be referred to as a fast serving cell change, and the change process can be correspondingly called a fast cell change process or fast serving cell change procedure. Hyphens ("-") can be added between these terms without modifying their meaning. In cellular networks where frequent DU handovers occur during UE mobility, for example when the carrier frequency in the air radio band can only provide short communication distances and dense cell density is required, the cumulative reduction in communication latency and signaling overhead will be very significant.

[0054] This document discloses various example implementations of mobility measurement / reporting and its configuration and signaling, serving cell change signaling, the cell change process, and data communication updates as a result of the cell change in the context of rapid cell changes that rely on low-level signaling and operations. Such a process can be performed with minimal user plane data flow interruption and can provide fast, efficient, and low-latency cell changes based on L1 / L2 UE mobility.

[0055] Typical L1 / L2-based fast inter-cell mobility

[0056] Generally, UE mobility can be achieved by: monitoring signal levels from various cells during UE movement, reporting cell measurement results to the network, performing a serving cell change procedure when specific cell handover conditions are met, and performing various procedures to update the current communication session. Each unit of the access network, including the UE and the WANN (or base station, referred to as NW in this document, representing the network side), participates in completing the entire mobility process. For example, the base station may be responsible for providing various configurations related to UE mobility, while the UE may be responsible for various cell measurements and reports. The base station, rather than the UE, may ultimately determine whether to perform a serving cell change and whether to trigger a cell handover, thereby balancing the UE load served by the source serving cell and the target serving cell. For example, the NW may determine and signal the target serving cell based on cell measurement reports from the UE. In some implementations of L1 / L2-centric fast mobility, similar to traditional L3-based mobility, the UE-side actions during the mobility process can be divided into two phases:

[0057] ●Preparation phase: This includes L1 and / or L3 measurements for each cell, and reporting the measurement results from the UE to the NW.

[0058] ●Execution phase: This includes the behavior of UE / NW at each network layer when receiving L1 / L2 signaling for mobility, including PHY layer (L1), MAC layer, RLC layer, PDCP (L2) and RRC (L3) layers, as well as the evaluation of the serving cell change results and the execution of the corresponding UE / NW operations after the serving cell change.

[0059] Preparation Phase for L1 / L2-Based Rapid Mobility - Overview

[0060] Figure 5 The flowchart illustrates the interaction between a sample UE and NW (e.g., a base station) during the preparation phase associated with the fast serving cell change process. In such a sample preparation phase, the general process may include, but is not limited to:

[0061] ●Step 1: NW configures cell measurement configuration and cell measurement reporting configuration for UE.

[0062] ●Step 2: The UE performs cell measurement according to the received cell measurement configuration, and determines whether to trigger a measurement result report to the NW based on the cell measurement reporting configuration, such as pre-configured reporting conditions (e.g., time-triggered conditions, such as periodic, semi-persistent periodic reports, or event-triggered conditions, as described in further detail below).

[0063] ●Step 3: If the cell measurement reporting conditions are met, the UE will report the cell measurement results related to the source cell and one or more candidate cells adjacent to the source cell to the NW.

[0064] Preparation phase for rapid L1 / L2 mobility - cell measurement configuration and cell measurement

[0065] Cell measurements can be of different types, including but not limited to L3 measurements and / or L1 measurements. Measurements within the serving cell can include those characteristics that can be used to determine the cell's signal quality and channel state, including but not limited to Synchronization System Block (SSB), Channel State Information Reference Signal (CSI-RS), etc. Reporting timing patterns can include periodic, aperiodic, semi-persistent periodic, or times triggered by predefined or configured events. For example, communication resources used to send cell measurement reports can include Physical Uplink Control Channel (PUCCH) resources and / or Physical Uplink Shared Channel (PUSCH) resources (in the time and frequency domains).

[0066] For example, measurements can be performed in L1 layer on the SSB and / or CSI-RS. L1 measurements may include:

[0067] ●L1 measurement of the source cell currently providing active services to the UE.

[0068] ●L1 measurement of one or more neighboring cells of the source cell.

[0069] In some implementations, cell measurement configuration and cell measurement reporting configuration can be signaled separately from the NW. In other implementations, these configurations can be signaled to the UE as a single signaling message. These configurations, or multiple configurations, can specify the measurements to be performed, the content to be reported, the report format, the report timing, the report triggering conditions, the report transmission resource allocation, etc.

[0070] For example, cell measurement configuration and cell measurement reporting configuration can indicate the following items for, for example, various CSI measurements:

[0071] ●CSI-MeasConfig specifies a set of CSI measurement and reporting configurations for the following CSIs.

[0072] ■CSI-ResourceConfig (e.g., periodic, non-periodic, and semi-persistent periodic reporting configurations).

[0073] ■NZP-CSI-RS-ResourceSet (i.e., a set of non-zero power CIS-RS resources measured in, for example, periodic, aperiodic, or semi-periodic manner).

[0074] ■CSI-RS-SSB-ResourceSet (i.e., a CIS-RS-SSB resource set measured in, for example, periodic, aperiodic, or semi-perpetual periodic manner).

[0075] ■CSI-ReportConfig (i.e., report trigger configuration, used to report cell measurements in a periodic, non-periodic, or semi-persistent periodic manner, or to report when triggered by an event).

[0076] The example cell measurement and cell measurement reporting configurations described above can be cell-specific. For example, different cell measurement and cell measurement reporting configurations can be provided to the source cell and neighboring cells. The neighboring cells to be measured can be configured as a candidate neighboring cell list for the source cell, for cell changes. The candidate cell list can be predetermined due to cell configuration within the area, or can be signaled from the network. Using the example implementation above, both / any of NZP-CSI-RS-ResourceSet and / or CSI-RS-SSB-ResourceSet can be associated with the cell indicated by PhysicalCellID or additionalPCIIndex.

[0077] Preparation Phase Based on Fast L1 / L2 Mobility - Cell Measurement Report

[0078] In some implementations, signaling and messaging for cell measurement reports can be performed at L1 and / or L2 layers, rather than L3. These layers can be predefined, pre-configured, or dynamically configured by the NW, from which cell measurement reports are sent. In some example implementations, the signaling / transmission of cell measurement reports can be specified as part of the aforementioned cell measurement reporting configuration. For example, cell measurement reports can be signaled / sent via:

[0079] ●L1 signaling and messaging (e.g., via uplink signaling, such as uplink control information (UCI), which can be transmitted via PUCCH or PUSCH); and / or

[0080] ●L2 signaling and messaging (e.g., via MACCE for reporting serving cell change processes).

[0081] For the L1 or L2 signaling / messaging mentioned above, the measurement results that can be included in the cell measurement report can also be predefined or pre-configured, for example, configured according to the cell measurement reporting configuration specified above. The following can be signaled as optional or alternative content that can be included in the cell measurement report:

[0082] 1. Direct measurement results of the source serving cell and one or more neighboring cells of the source serving cell, which may include, for example, at least one of the following:

[0083] ① Direct measurement results of one or more neighboring cells that are potential target cells for cell relocation;

[0084] ② Direct measurement results from the source serving cell; or

[0085] 2. Identifiers and related information of one or more neighboring cells of the current source serving cell suitable for handover, such as:

[0086] ①Physical Cell Information (PCI) indicates one or more neighboring physical cells that the UE determines are suitable as the target cell for serving cell change;

[0087] ② Optionally, additional beam information for the indicated physical cell is used to indicate the beams of suitable neighboring physical cells that are suitable for the serving beam change as the serving cell.

[0088] The first alternative described above may be particularly suitable for L1 signaling / messaging in L1 cell measurement reporting, as L1 measurements are directly included in the L1 measurement reporting message without involving other higher layers. By reporting direct measurement results via L1 or L2 signaling / messaging, the NW makes decisions to identify and characterize the target serving cell for serving cell changes based on the direct measurement results reported in the cell measurement report and other factors known to the NW. Direct measurement results of the source cell or one or more neighboring cells may include overall measurement results of neighboring cells and individual beams within each neighboring cell.

[0089] Regarding the second alternative, the UE can select a suitable neighboring cell for rapid serving cell change based on direct cell measurements performed at Layer-1 within the UE. For example, a selection can be made from a set of candidate cells, which, as described above, are predetermined, pre-configured, or signaled from the NW. One or more such suitable neighboring cells can be selected and reported. Upon receiving the selection, the NW can further determine the target serving cell for rapid serving cell change.

[0090] Regarding the second alternative described above, the cell measurement report may include physical cell information of any suitable neighboring cells and beam information of any suitable beam. Such information may include, but is not limited to:

[0091] ● Appropriate physical cell information of neighboring cells, including at least one of the following:

[0092] o Physical community identifier;

[0093] o The position or index of the appropriate cell in the candidate cell list (e.g., 0 represents the first cell information in the candidate cell information list, and 1 represents the second cell information in the candidate cell information list, etc.);

[0094] ● Beam information of the appropriate physical cell, including at least one of the following:

[0095] o The CSI-RS ID and / or SSB identifier associated with the beam;

[0096] o The beam position or index associated with the candidate beam list of the physical cell (i.e., 0 represents the first beam in the candidate beam list, and 1 represents the second beam in the candidate beam list, and so on).

[0097] In some implementations of L1 signaling / messaging, such physical cell and beam information can be reported using code points. In other implementations, physical cell and beam information can be indicated by one or more bitmaps for L1 or L2 signaling / messaging. For example, a physical cell bitmap can be included in a cell measurement report to indicate one or more suitable neighboring cells in a set of candidate cells for serving cell change. Furthermore, in a suitable physical cell, a beam bitmap can be included in the cell measurement report to indicate one or more beams of the physical cell that the UE deems suitable for serving cell change. Besides code points or bitmaps, other methods can be implemented for cell measurement reports to indicate the aforementioned physical cell and beam information.

[0098] In some other example implementations, the cell measurement report may include a combination of the two alternatives described above. Specifically, via L1 or L2 signaling / messaging, the cell measurement report may include direct measurement results of one or more suitable neighboring cells or beams selected by the UE from candidate cells or beams for serving cell changes.

[0099] Preparation phase for fast L1 / L2 mobility - Cell measurement reporting via trigger event conditions

[0100] In some implementations, cell measurement results can be reported to the NW according to predefined or pre-configured timing. For example, cell measurement results can be reported periodically in pre-configured time slots.

[0101] In some other example implementations, cell measurement reports may be sent based on one or more trigger events. Whether cell measurement reports are sent based on time or trigger events can be pre-configured, for example, as indicated in the cell measurement reporting configuration described above.

[0102] Regarding event-based cell measurement reporting, for example, a cell measurement report can be triggered at L1 or L2 by satisfying one or more of the following event conditions:

[0103] 1. The measurement results of the source serving cell meet the following conditions (referred to as the Source Cell Discretionary Principle (BSC)):

[0104] The measurement result of the source cell is ≤ threshold 1 + offset 1 (1)

[0105] and / or

[0106] 2: The measurement results of at least one candidate neighboring target cell meet the following established conditions (referred to as the Target Cell Discrimination Criterion (GTC)):

[0107] The measurement result of the candidate target cell is ≥ threshold2 + offset2(2)

[0108] Meeting the above BSC condition indicates that the source serving cell may not be suitable for providing service to the UE and a change of serving cell may be necessary. Meeting the above GTC condition indicates that at least one neighboring serving cell is suitable as a potential target cell for handover. The above "Threshold 1" represents the baseline cell signal quality threshold used to determine whether the source serving cell has become unsuitable for supporting the communication link, while "Offset 1" represents the tolerance level of Threshold 1. Similarly, the above "Threshold 2" represents the baseline cell signal quality threshold used to determine whether a neighboring cell is suitable as a potential target serving cell for serving cell change, while "Offset 2" represents the tolerance level of Threshold 2. Each of "Threshold 1," "Threshold 2," "Offset 1," and "Offset 2" can be predetermined, pre-configured, or dynamically configured. In some example implementations, the baseline threshold can be predefined, while the tolerance level can be configured.

[0109] In some cases, especially when the UE is at a cell edge or boundary, the relative signal between the current source serving cell and one or more neighboring cells may fluctuate significantly. Therefore, using this mechanism to determine whether the current source serving cell is poor and whether at least one neighboring cell is good (based on the above mechanism) may lead to frequent serving cell changes due to the ping-pong effect. The ping-pong effect can cause significant inefficiency and communication overhead. To avoid or reduce the ping-pong effect in L1 / L2 mobility, and considering the computational and signal processing limitations of the L1 / L2 layers, the UE can employ the following enhancement mechanism for event-based triggering of sending cell measurement results to the NW:

[0110] ●BSC condition: N consecutive measurement results of the source serving cell satisfy the conditions of formula (1) above, and / or

[0111] ●GTC condition: At the same time as or after the measurement of the source serving cell, the M consecutive measurement results of at least one neighboring cell satisfy the condition of formula (2) above.

[0112] In another specific implementation to avoid or reduce the ping-pong effect, the UE can employ an alternative enhancement mechanism for event-based triggering of sending cell measurement results to the NW:

[0113] ●BSC condition: The average measurement result of N consecutive measurements of the source serving cell satisfies the condition of formula (1) above, and / or

[0114] ●GTC condition: The average measurement result of M consecutive measurements from at least one neighboring cell satisfies the condition of formula (2) above.

[0115] In some example implementations, the measurement results of the source serving cell or neighboring cells can be cell-level or beam-level measurements. Cell-level measurements can be obtained, for example, from the measurements of one or more beams. Beam-level measurements can, for example, include a predetermined or pre-configured number P of optimal beams for a specific cell. In the above implementations, M, N, and P can be predefined, pre-configured, or dynamically configured positive integers.

[0116] The aforementioned N consecutive source cell measurement results and M consecutive neighboring cell measurement results correspond to the source cell measurement time window and the neighboring cell measurement time window, respectively. The enhancement mechanism described above represents a filtering process that smooths the consecutive measurement results, more accurately representing the channel quality of each cell, thereby avoiding or reducing the ping-pong effect.

[0117] In some example implementations, the measurement results may include one or more of the following: Reference Signal Received Power (RSRP), Signal-to-Interference-Noise Ratio (SINR), Reference Signal Received Quality (RSRQ) level, etc., as a reflection of the channel state. When more than one result is used, the results may be aggregated or combined (e.g., averaged, weighted averaged, etc.), and correspondingly, the baseline thresholds and offset values ​​in Equations (1) and (2) above may also be aggregated or combined. Alternatively, each of the multiple measurement results in a cell may be associated with its own threshold and offset, thereby providing sub-conditions based on Equations (1) and (2). For example, each of these formulas may be considered satisfied when all or most of the sub-conditions are satisfied.

[0118] As an example of the above implementation, when the number of consecutive measurements indicating that the source cell is a poor cell is equal to or greater than N, and / or the number of consecutive measurements indicating that at least one candidate neighbor cell among the candidate neighbor cells is a superior target cell is equal to or greater than M, the MAC layer can generate and / or send a MAC CE or notify the L1 layer to send an L1 message to report the cell measurement results to the NW. Therefore, the MAC layer can be configured to track the number of BSC and GTC measurements using simple logic and counters, thus eliminating the need for the MAC layer to possess complex computational capabilities.

[0119] In some implementations of simple logic and counters, the MAC layer or entity can maintain one or two counters, referred to as counter A and counter B. When an instruction regarding the BSC is received from a lower layer, the MAC layer or entity can increment counter A by 1, and when an instruction regarding the GTC is received from a lower layer, the MAC layer or entity can increment counter B by 1. Through this implementation, one or two timers can be maintained at the MAC layer accordingly, referred to as timer A and timer B. Timer A can be associated with counter A, and / or timer B can be associated with counter B. When counter A increments, timer A can be started or restarted, and when counter B increments, timer B can be started or restarted. When timer A expires, counter A can be reset to 0, and when timer B expires, counter B can be reset to 0. Additionally, one or two maximum values ​​M and / or N can be pre-configured for counters A and counter B to trigger or send cell measurement reports. When counters A and / or counter B reach their maximum values ​​M and / or N, cell measurement reports can be triggered and / or sent.

[0120] As an example of the above implementation, when notified by the L1 layer to send a MAC CE, the MAC layer can generate and / or send a MAC CE. Alternatively, when the L1 layer detects that the average of N consecutive measurement results indicates a source cell discrimination condition, and / or when the L1 layer detects that the average of M consecutive measurement results indicates that at least one candidate neighbor cell among the candidate neighbor cells is the preferred target cell, the L1 layer can send an L1 message to report the cell measurement results to the NW. Therefore, the MAC layer can be configured to track indications from lower layers regarding BSC and GTC information to generate and send MAC CEs for cell measurement reports. Thus, when receiving indications of BSC and / or GTC information from lower layers, the MAC layer can trigger and / or send a cell measurement report.

[0121] In some other implementations, the event triggering condition may be based on a combination of source cell measurement results (referred to as "first cell measurement results") and one or more neighboring cell measurement results (referred to as "second cell measurement results"). For example, the difference between the first cell measurement results and the second cell measurement results can be used as the basis for a triggering event for reporting cell measurement results. Specifically, an example triggering event condition may be represented as follows:

[0122] The result of the neighboring cell - the result of the source cell ≥ threshold 3 + offset 3, (3)

[0123] The definitions or configurations of “threshold 3” and “offset 3” can be similar to those of “threshold 1”, “threshold 2”, “offset 1” and “offset 2” mentioned above.

[0124] To avoid or reduce the ping-pong effect of L1 / L2 mobility, and considering the limited L1 / L2 computing power, the above differential measurements can be performed continuously within the measurement window, and a cell measurement report can be triggered when X consecutive different measurements satisfy the conditions in formula (3) above. In the specific details of this implementation, a counter (called counter C) and a timer (called timer C) can be introduced in the L2 layer. For example, counter C can be associated with timer C, and counter C can be incremented by 1 when the MAC layer receives an indication from the lower layer that satisfies formula (3). Timer C can be started or restarted as long as counter C is incrementing. When timer C expires, counter C can be reset to 0. In addition, a maximum value X can be pre-configured, and when counter C reaches the maximum value X, the L2 layer can generate and / or send a cell measurement report, and / or the L2 layer can instruct the lower layer to generate and / or send a cell measurement report when counter C reaches the maximum value X.

[0125] In another implementation, to avoid or reduce the ping-pong effect of L1 / L2 mobility and considering the limited L1 / L2 computing power, the measurement results of neighboring cells can be the average of Y consecutive measurements of neighboring cells, while the measurement results of the source cell can be the average of Y consecutive measurements of the source serving cell. In the details of this implementation, the L2 layer can trigger and / or generate a cell measurement report upon receiving an instruction from a lower layer that satisfies formula (3), and / or the L1 layer can trigger and / or generate a cell measurement report when the difference satisfies formula (3).

[0126] Similarly, the measurement results reflected in formula (3) above can be cell-level differential measurement results or beam-level differential measurement results. Cell-level differential measurement results can be obtained from differential measurement results of one or more beams. For example, beam-level measurement results may include a predetermined or pre-configured number P optimal beams for a specific cell. Differential measurement results may be differential RSRP, SINR, RSRQ, and / or other differential characteristics reflecting the channel state of the cell under test.

[0127] In the various implementations of the cell measurement report triggered by the above events, the triggering events related to neighboring cells can be configured for each candidate neighboring cell, for each list of candidate neighboring cells, or for each group of cells.

[0128] Trigger events for different candidate cells, different candidate cell lists, or different candidate cell groups can be configured differently. For example, each candidate cell, each candidate cell list, or each candidate cell group can be configured with its own trigger event independently. For example, a neighboring candidate cell can be associated with a trigger event based on formulas (1) and (2) under filtering conditions, while another neighboring candidate cell can be associated with a trigger event based on formula (3) under filtering conditions, and vice versa. Then, any neighboring cell that satisfies its respective trigger event will cause a cell measurement report to be sent.

[0129] In some other implementations, one or more of the following events may also trigger a cell measurement report:

[0130] ● A beam failure (BF) is detected on the source serving cell, and fewer than P suitable beams of the source serving cell can be identified, where P is a predetermined, configured positive integer; and / or

[0131] ● A radio link failure was detected for the source serving cell.

[0132] Meeting these conditions indicates that the source serving cell can no longer support communication and a cell handover is required. The triggered cell measurement report will be used to urge the NW to provide and designate a target serving cell for the service cell change, regardless of the quality of the target cell.

[0133] Execution Phase - Overview

[0134] In some implementations, once cell measurement results are reported, the NW can determine, based on these results, whether a fast serving cell change should be implemented for the reporting UE. If the decision is made to proceed with the fast serving cell change, the NW can identify the target serving cell and begin the execution phase of the fast serving cell change.

[0135] Figure 6 This section describes example steps for the execution phase of a fast-service cell change. For example... Figure 6 As shown, these steps may include:

[0136] Step 1: The source cell sends L1 and / or L2 signaling messages to the UE to trigger the fast serving cell change process.

[0137] Step 2: The UE performs a set of fast serving cell change operations.

[0138] Step 3: The UE notifies the target serving cell of the fast serving cell change.

[0139] Step 4: Target serving cell confirms UE notification.

[0140] Step 5: If the fast serving cell change fails based on the response or no response from the target serving cell in Step 4, the UE performs further operations.

[0141] L1 / L2 signaling that triggers rapid serving cell change

[0142] The source serving cell can trigger a rapid serving cell change based on L1 / L2 signaling / messaging. For example, the trigger can be entirely based on L1 signaling / messaging, such as via downlink control information (DCI) messages. In this example implementation, the L1-triggered DCI message may include at least one of a set of information items, including but not limited to:

[0143] ●Target service area information:

[0144] ○ Physical Cell ID (PCI): Indicates the target serving cell to which the UE should be transferred;

[0145] ○ Serving Cell ID: Indicates the target serving cell to which the UE should be transferred; or

[0146] ○ Candidate Cell ID: Indicates the target serving cell that the UE should transfer to.

[0147] ● Beam Information: For example, used to indicate which Transport Configuration Indicator (TCI) state can be activated for uplink and / or downlink after the UE hands over to the target serving cell. In some implementations, the beam indication may be based on the CSI-RS ID and / or SSBID. In some implementations, the beam indication may be indicated via the TCI state ID. In some implementations, the Transmit / Receive Point (TRP) indication may be indicated via the position of the TRP in the TRP list.

[0148] ●Time Advance (TA) Information: Indicates the TA value of the target serving cell.

[0149] ● Preamble Index: Instructs the UE to perform RACH on the indicated target serving cell.

[0150] ●RO Index: The RACH timing (RO) index that indicates when the UE will perform RACH on the indicated target serving cell.

[0151] ●Cell Radio Network Temporary Identifier (C-RNTI): Indicates a new C-RNTI when the UE transfers to the target serving cell.

[0152] ●Keycode: Used by the UE to authenticate L1 signaling from the NW (source serving cell). It can also be included in the RRC configuration of the target serving cell indicated by the physical cell information.

[0153] In some other example implementations, the source serving cell triggering a fast serving cell change process can be entirely based on L2 signaling / messaging, for example via one or more MAC CEs. In this example implementation, the L2-triggered MAC CE may include at least one of a set of information items similar to the information items listed above for LI-triggered DCI.

[0154] In other example implementations, L1 DCI and L2 MAC CE can be used together to trigger a fast serving cell change process. For example, one or more MAC CEs can be used to activate one or more candidate cells in a candidate cell list to achieve a fast serving cell change. Such a MAC CE can be sent to one or more candidate cells for activation. The MAC CE can be further sent to the UE as part of the triggering process to indicate to the UE which candidate serving cells are activated for fast serving cell change. Furthermore, one or more DCIs can be used to actually trigger a fast serving cell change to a specific target serving cell among those candidate serving cells activated by one or more MAC CEs. In one implementation, the MAC CE used to activate a candidate serving cell for fast serving cell change may include at least one of the following:

[0155] ● Target serving cell information can be indicated by the physical cell identifier or by the index of the candidate serving cell in the candidate target serving cell list.

[0156] ● Beam information: Beam information associated with each current target serving cell in the same MAC CE, which may be indicated by SSB information and / or CSI-RS information and / or TCI status identifier.

[0157] UE Fast Serving Cell Change Operation - Overview

[0158] The following describes a set of example fast serving cell change operations performed by a UE in response to receiving L1 or L2 fast serving cell change signaling or triggering.

[0159] For example, the L2 layer of the UE can perform at least one of the following:

[0160] ● Keycode verification used to verify fast serving cell change signaling.

[0161] ● One or more Random Access Channel (RACH) procedures used to access the target serving cell.

[0162] ● One or more complete MAC layer resets or adapted MAC layer resets.

[0163] ● Activate / deactivate one or more serving cells.

[0164] In another example, one or more RLC layer operations can also be performed in the UE. Additionally, one or more PDCP layer operations can be performed in the UE. Furthermore, one or more RRC layer operations can be performed in the UE.

[0165] The following sections will describe in further detail these example operations of the UE in response to fast serving cell change signaling at various network layers.

[0166] UE Fast Serving Cell Change Operation - MAC Layer

[0167] In some implementations, after receiving Fast Serving Cell Change signaling from the source serving cell, the UE may first perform key code verification for the Fast Serving Cell Change. In some example implementations, if the key code in the received L1 / L2 signaling for Fast Serving Cell Change matches the value of a reference key code in the RRC configuration associated with the target serving cell and / or the source serving cell for Fast Serving Cell Change, the UE can determine that the key code verification was successful. The UE can then continue to notify the upper layers of the Fast Serving Cell Change. Otherwise, the UE can ignore the received L1 / L2 Fast Serving Cell Change signaling and not perform any further serving cell change operations.

[0168] After successful authentication, the UE may, for example, execute one or more RACH procedures to access the target serving cell. For instance, the RACH procedure may involve the UE first determining whether any RACH operation needs to be performed. More specifically, the UE may determine, based on Fast Serving Cell Change signaling, whether to execute a RACH procedure to access the target serving cell as part of the serving cell change process, and in response to determining that a RACH procedure needs to be performed, continue executing the RACH procedure.

[0169] In some example implementations, as long as the L1 / L2 signaling indicating a change in the fast serving cell is received and successfully verified through the key code process described above, a RACH operation can be initiated in the target serving cell.

[0170] In some alternative implementations, whether a RACH operation should be initiated on the target serving cell when L1 / L2 signaling indicating a fast serving cell change is received can be determined by one or more of the following explicit instructions:

[0171] ● An explicit RACH procedure indication pre-stored in the RRC reconfiguration message associated with the target serving cell. For example, the RRC reconfiguration message may contain an information element indicating whether a RACH procedure is required.

[0172] ● A RACH configuration associated with the target serving cell exists.

[0173] ● Explicit RACH triggering indication for fast serving cell changes in Layer-1 or Layer-2 signaling.

[0174] If one or more of the above explicit conditions are met, the RACH operation can be performed.

[0175] In some alternative implementations, whether a RACH operation should be initiated on the target serving cell when L1 / L2 signaling indicating a fast serving cell change is received can be determined by one or more of the following implicit indicators:

[0176] ● The time advance (TA) value associated with the target serving cell is invalid.

[0177] ● There is no TA value or time advance group (TAG) ID associated with the target serving cell.

[0178] ● No TA value is present in the fast-serving cell change signaling.

[0179] ● Perform a MAC reset.

[0180] If one or more of the above implicit conditions are met, the RACH operation can be performed.

[0181] In some example implementations, the RACH operation can proceed once the UE determines that it wants to perform the RACH procedure on the target serving cell. The various parameters of the RACH operation can be pre-configured in the RRC configuration associated with the target serving cell. Furthermore, the RACH procedure can be a contention-free RACH (CFRA) procedure or a contention-based RACH (CBRA) procedure.

[0182] In some example implementations, when the NW provides a RACH preamble identifier and / or RACH timing (RO) identifier for Fast Serving Cell Change or RRC signaling via Layer-1 or Layer-2 signaling, the UE can determine to follow the CFRA procedure and can continue to perform the CFRA procedure using the RACH preamble identifier and RO identifier explicitly provided by the NW.

[0183] In some example implementations, when there is no RACH preamble identifier or the RACH RO identifier is signaled, or the current RACH preamble identifier is equal to 0b000000 or the dedicated RRC configuration is not signaled, the UE may determine to follow the CBRA procedure and may continue to select a target SSB with a synchronization signal-RSRP (SS-RSRP) higher than the reference signal received power threshold and the corresponding RACH preamble from multiple signal blocks (SSBs) to perform the CBRA procedure.

[0184] In some example implementations, a normal full MAC reset or an adaptive MAC reset can be performed. For example, the UE can first determine whether to perform a full MAC reset or an adaptive MAC reset. For instance, an explicit RRC information element in the RRC configuration associated with the target serving cell or a list of target serving cells that includes the target serving cell can indicate to the UE whether to perform a normal full MAC reset or an adaptive MAC reset. As another example, an explicit indication in the fast serving cell change signaling can indicate to the UE whether to perform a normal full MAC reset or an adaptive MAC reset.

[0185] In some implementations, adapting to a MAC reset may include performing one or more of the following:

[0186] ● Cancel the ongoing RACH process;

[0187] ● Refresh the RACH message-3 buffer;

[0188] ● Refresh the RACH message-A buffer;

[0189] ● Cancel the beam failure recovery (BFR) procedure triggered on the target serving cell;

[0190] ● Cancel the Power Headroom Report (PHR) procedure triggered on the target cell;

[0191] ● Cancellation of consistent Listen-After-Talk (LBT) triggering for the original cell and target serving cell of the wireless device failed;

[0192] ● Reset the beam failure instance BFI counter (BFI-COUNTER) for the original cell and target serving cell of the wireless device;

[0193] ●Reset LBT_COUNTER for the original cell and target serving cell used by the wireless device;

[0194] ● Cancel the triggered Schedule Request (SR) procedure;

[0195] ● Refresh the soft buffer for all downlink Hybrid Automatic Repeat Request (DLHARQ) procedures used in the original cell and treat the transmission of the next received transport block (TB) as the first transmission; or

[0196] ● Set the new data indicator (NDI) for all UL HARQ process IDs of the original cell and the target cell to zero.

[0197] In some implementations, an adaptive MAC reset can be a subset of a normal full MAC reset. In some implementations, some operations in an adaptive MAC reset can be modified from the corresponding normal MAC reset operations. In some implementations, the main difference between a full MAC reset and an adaptive MAC reset might be that a full MAC reset includes treating all TA timers as expiring for all Time Advance Groups (TAGs), while an adaptive MAC reset may not include this consideration. For adaptive MAC resets, some example modifications and adaptations for fast serving cell changes are reflected in the list above.

[0198] In some implementations, an AllowedServingCell for an LCH (e.g., mapped to the DRB of the serving cell) can be determined. In one implementation, if an LCH is configured to contain an AllowedServingCell for the target cell, and the target cell is unique, and if the target cell is one of the SCells, the UE considers the serving cell with ID=0 as the AllowedServingCell. In one implementation, an AllowedServingCell for an LCH MACCE can be introduced to dynamically adjust the AllowedServingCells of one or more LCHs. In another implementation, the MACCE may include at least one of the following:

[0199] ●LCH ID: Indicates the LCH used for remapping to the serving cell.

[0200] ●Serving Cell ID: Indicates the serving cell to which the LCH should be mapped.

[0201] In one implementation, the NW determines whether to adjust the allowed serving cells of the LCH via RRC reconfiguration before sending the L1 / L2 signal for serving cell change or after the serving cell change is sent to the UE.

[0202] In some implementations, the UE's MAC layer operation in response to receiving a fast serving cell change signaling may further include serving cell activation and deactivation operations. The UE may determine whether to perform any serving cell deactivation based on the indication contained in the fast serving cell change signaling. For example, when receiving and verifying an L1 / L2 fast serving cell change signaling, the UE may deactivate all activated serving cells, such as SCells of cell groups associated with a MAC entity. For example, the UE may deactivate all SCells of an MCG in the event of a PCell change, or all SCells of an SCG in the event of a PSCell change. In some example implementations, the UE may deactivate all activated SCells not included in the serving cell list indicated by an RRC information element in an RRC configuration associated with a target serving cell or candidate target serving cell list.

[0203] UE Fast Serving Cell Change Operation - RLC Layer

[0204] In some implementations, upon receiving and verifying L1 / L2 Fast Serving Cell Change signaling, the UE may perform one or more RLC layer operations. For example, RLC layer operations may include re-establishing an RLC entity. In some implementations, whether an RLC entity needs to be re-established may be indicated by an information element in the RRC configuration associated with the target serving cell or by an indication (e.g., a flag indicator) in the Fast Serving Cell Change signaling. In some implementations, this indication information element may be configured for each RLC entity in the cell group involved. In other implementations, the indication information element may be configured for each cell group.

[0205] UE Fast Serving Cell Change Operation - PDCP Layer

[0206] In some implementations, when the UE receives and verifies L1 / L2 fast serving cell change signaling, it can perform one or more PDCP layer operations.

[0207] In some implementations, when the Signal Radio Bearer (SRB) is configured for carrier aggregation (CA) replication, the UE can suspend PDCP replication of the SRB until the serving cell change process is complete. In this implementation, the PDCP entity may generate only one PDCP PDU and send it to the lower layer of the primary path.

[0208] In some implementations, when only two RLC entities are associated with a PDCP replication of a data radio bearer (DRB), the UE can automatically deactivate the PDCP replication upon receiving fast serving cell change signaling, regardless of whether it is an MCG or SCG.

[0209] In some other implementations, when two or more RLC entities are associated with a DRB’s PDCP replication, the UE can deactivate RLC entities other than the primary RLC entity used for PDCP replication when receiving fast serving cell change signaling, regardless of the MCG and SCG.

[0210] In another example implementation, when there are more than two RLC entities associated with PDCP repetition and the RLC entities belong to different CGs, if the primary path is located in the MCG and if L1 / L2 signaling for fast serving cell change is received for the SCG, the UE can deactivate PDCP repetition for all RLC entities in the SCG. In yet another implementation, when there are more than two RLC entities associated with PDCP repetition and the RLC entities belong to different CGs, if the primary path is located in the SCG and if L1 / L2 signaling for fast serving cell change is received for the MCG, the UE can deactivate PDCP repetition for all RLC entities in the MCG.

[0211] In some implementations, the UE can perform PDCP recovery. For example, an information element can be included in the RRC configuration associated with the target cell and / or candidate target cell list. The information element can be used to indicate to the UE whether the UE needs to perform PDCP recovery for the Acknowled Mode (AM) DRB. If indicated, the UE can continue to perform such PDCP recovery for the AM DRB.

[0212] UE Fast Serving Cell Change Operation - RRC Layer

[0213] In some example implementations, when the UE receives and verifies L1 / L2 fast serving cell change signaling, it can perform one or more RRC layer operations. The RRC layer operations can depend on various RRC models. Two example RRC models are described below along with the corresponding RRC layer operations that the UE can perform under each RRC model.

[0214] RRC Mode #1

[0215] In Example RRC Mode #1, fast serving cell change based on L1 / L2 signaling can continue to be implemented using the pre-configured RRCReconfiguration message. More specifically, the UE can still follow the normal behavior of the RRC reconfiguration process to reuse, for example, the information element reconfigurationWithSync to implement fast serving cell change.

[0216] In some implementations, the NW can pre-configure the UE using L1L2CentricRRCReconfig, which includes the RRCReconfiguration message. The UE can then store the L1L2CentricRRCReconfig information in UE variables for rapid serving cell change based on L1 / L2 signaling. An example RRC structure is shown in Table 1 below. In some example implementations, a key code can be configured in this example RRC structure for rapid serving cell change.

[0217] Table 1

[0218]

[0219] As shown in Table 1, the RRC unit reoconfigurationWithSync2 can be introduced into the information unit of CellGroupConfig. This unit is mutually exclusive with reconfigurationWithSync.

[0220] In some implementations, if ReconfigurewithSync is received / configured in the RRCReconfiguration message for fast serving cell change, the MAC layer can be completely reset in the normal manner, and the TA values ​​of all TAGs can be considered invalid. Conversely, if ReconfigurewithSync2 is received / configured in the RRCReconfiguration message for fast serving cell change, the MAC layer can be adaptively reset as described above, and the TA values ​​of the MAC entities can still be considered valid if the corresponding TA timers have not expired.

[0221] In some implementations of ReconfigurationWithSync2, the following information units may be further included:

[0222] ●SCellID / ServingCellID / AssistanceCellID / CandidateCellID / Physic

[0223] alCellID: Indicates the target cell for fast serving cell change. In one implementation, the UE may apply the cell configuration associated with this information element (i.e., ServingCellConfigComm and / or ServingCellConfig) as the serving cell configuration for fast serving cell change.

[0224] ●ServingCellConfigCommon: A cell-specific parameter for the target serving cell.

[0225] ●ServingCellConfig: A UE-specific parameter for the target serving cell.

[0226] ●NewUE-ID: Indicates the new C-RNTI that should be used after a fast serving cell change. If it does not exist, the old C-RNTI should be retained for use when transferring to the target serving cell.

[0227] Using RRC model #1, and in some example implementations, the UE can store the current CellGroupConfiguration and / or C-RNTI and / or servingCellConfigCommon and / or servingCellConfigDedicated into a list of candidate target cells with a minimized L1L2CentricRRCReconfigID, which is currently available when receiving an indication of fast serving cell change from a lower layer.

[0228] In some other implementations, the UE may store the current CellGroupConfiguration and / or C-RNTI and / or servingCellConfigCommon and / or servingCellConfigDedicated into a list of candidate target cells with the sameL1L2CentricRRCReconfigID, which belongs to the target serving cell indicated by L1 / L2 signaling used for fast serving cell changes.

[0229] Therefore, the UE can perform the following example steps under RRC model #1:

[0230] ●Step 1: The UE can determine whether it has received an indication of fast serving cell change from a lower layer. If yes, proceed to step 2; otherwise, proceed to the end.

[0231] ●Step 2: The UE can perform the RRC reconfiguration process according to the RRCReconfiguration message of the target serving cell stored in L1L2CentricRRCReconfigToADDmodList as indicated by the instruction from the lower layer, and then proceed to step 3.

[0232] ●Step 3: The UE can store the current CellGroupConfiguration and / or C-RNTI and / or servingCellConfigCommon and / or servingCellConfigDedicated from the RRCReconfiguration message of the source serving cell into L1L2CentricRRCReconfigToADDmodList with the sameL1L2CentricRRCReconfigID of the target serving cell.

[0233] In another example implementation, the UE can perform the following steps under RRC model #1:

[0234] ●Step 1: The UE can determine whether the RRC reconfiguration message includes reconfigurationWithSync2 or reconfigurationWithSync. If it includes reconfigurationWithSync, proceed to step 2A; otherwise, proceed to step 2B.

[0235] ●Step 2A: The UE can normally perform RRC reconfiguration for fast serving cell change (i.e., normal full MAC reset), and then proceed to the end.

[0236] ●Step 2B: The UE can utilize the MAC entity's adaptation reset to perform RRC reconfiguration for rapid serving cell change. Then proceed to the end.

[0237] RRC Model #2

[0238] In Example RRC Model #2, the candidate target serving cell configuration for rapid serving cell change can be in one or more cell configuration lists, which can be configured in CellGroupConfig and / or CellConfigSpCellConfig.

[0239] In some example implementations, if the target serving cell is one of the SCells, the UE can apply differential reconfiguration of the target serving cells in the list to fast serving cell change. In this implementation, the deltaConfigurationForSpCellChange information element may include at least one of the following:

[0240] ●PUCCH channel related configuration

[0241] ●New UE identifier

[0242] ● Radio link monitoring related configuration

[0243] ● Beam failure recovery related configurations

[0244] ●RACH related configurations, including:

[0245] ■RACH Resource Allocation

[0246] ■ Dedicated RACH resource configuration

[0247] ●ResetMAC / PartialResetMAC flag

[0248] ●Timer for quick service cell changes

[0249] ●Key Code

[0250] In some example implementations, if the target serving cell is not one of the SCells in SCellToAddModlist, the UE can apply the RRC configuration for the target serving cell to Fast Serving Cell Change. In other words, the target serving cell cannot be activated as an SCell, and the RRC configuration for the target serving cell can include at least one of the following:

[0251] ●ServingCellConfigCommon: Indicates cell-specific parameters for the target serving cell.

[0252] ●ServingCellConfigDedicated: Indicates UE-specific parameters for the target serving cell.

[0253] ●RACH related configuration: Indicates the RACH resources / parameters of the target serving cell, including

[0254] At least one of the following:

[0255] ■RACH Resource Allocation

[0256] ■ Dedicated RACH resource configuration

[0257] ● Timer for Fast Serving Cell Change: A timer used by the UE to determine whether the Fast Serving Cell Change has been successfully terminated.

[0258] ●NewUEIdentity: The C-RNTI that should be used after a fast-serving cell change.

[0259] ●ResetMAC: Indicates whether the MAC entity should be reset.

[0260] ●TAG ID: Indicates the TAG to which the target serving cell belongs.

[0261] ●Key Code

[0262] Therefore, the UE can perform the following example steps under RRC model #2:

[0263] ●Step 1: The UE can determine whether it has received an indication of fast serving cell change from a lower layer. If so, proceed to step 2. Otherwise, proceed to the end.

[0264] ●Step 2: The UE can determine that the RRC configuration of the target serving cell indicated by the L1 / L2 signaling from the lower layer is an SCell in SCellToAddmodList. If it is, proceed to step 3; otherwise, proceed to step 4.

[0265] ●Step 3: The UE can adapt to at least one of the following operations, and then proceed to the end.

[0266] ■ Configure SCell based on the differential (delta) configuration of the target serving cell.

[0267] ■Activate the SCell if it is not already activated.

[0268] ■ Release the serving cell configuration and notify lower layers to release the resources of the currently serving cell.

[0269] ■ Treating SCell as a serving cell, in one implementation, the serving cell ID of SCell is considered to be equal to 0.

[0270] ■ Reset or adapt the MAC entity of the cell group (e.g., partially reset).

[0271] ■ Apply ueNewIdentity as the C-RNTI for this cell group (if it exists).

[0272] ●Step 4: The UE can adapt to at least one of the following operations, and then proceed to the end.

[0273] ■ Configure the lower layer for the target serving cell according to ServingCellConfigCommon (if it exists).

[0274] ■ Configure the lower tier for the target serving cell based on ServigCellConfigDedicated (if it exists).

[0275] ■ Reset or adapt the MAC entity of the cell group (e.g., partially reset).

[0276] ■ Apply ueNewIdentity as the C-RNTI for the cell group (if it exists).

[0277] Notification to target service area

[0278] After the UE performs the various fast serving cell change operations described above, it can send a notification of completion of the fast serving cell change operation to the target serving cell. For example, such a notification can be sent in at least one of the following formats:

[0279] ● Notifications similar to those in a Mac CE, including one of the following:

[0280] ■C-RNTI MAC CE

[0281] ■BSR MAC CE

[0282] ■ New MAC CE, which may contain information about the UE identifier and / or keycode configured in the RRC configuration associated with the target serving cell / candidate target serving cell list / source cell, and / or in the L1 / L2 signaling used to trigger fast serving cell change.

[0283] ●UCI, such as scheduling requests

[0284] ●RRC Message

[0285] ●RACH process

[0286] In some implementations involving MAC CE, a scheduling request (SR) should be triggered if no PUSCH is available for transmitting them.

[0287] Response to notification from the target serving cell

[0288] The response from the target serving cell to the above notification may include acknowledgment (ACK), negative acknowledgment (NACK), or no response.

[0289] In some implementations, if the RACH procedure has been performed for a fast serving cell based on L1 / L2 signaling, the successful termination of the RACH procedure can be regarded as an ACK indication.

[0290] In some implementations, the DCI that receives a new C-RNTI can be regarded as an ACK indication.

[0291] In some implementations, the reception of a MAC CE can be considered an ACK indication. In this implementation, the MAC CE may consist only of a subheading without a payload, or the MAC CE may include at least one of the following:

[0292] ●Key code; or

[0293] ●New C-RNTI

[0294] In some implementations, an ACK indication can be considered received when a UL authorization for a new transmission of a HARQ process ID used to send a notification to the NW is received.

[0295] In some implementations, a timer (FastServingCellChangeTimer) configured in the configuration associated with the target serving cell and / or the list of candidate target serving cells and / or the source serving cell can be used to determine whether a fast serving cell change based on L1 / L2 signaling was successful. For example, if no ACK is received before the FastServingCellChangeTimer expires, it can be assumed that a NACK indication has been received.

[0296] UE actions in response to a NACK notification

[0297] If the UE determines that a NACK was indicated from the target serving cell, for example, the UE can trigger an RRC re-establishment procedure. In another example, if the source serving cell configuration has not been released and / or has been stored and is still available, the UE can revert to the source serving cell.

[0298] The foregoing description and accompanying drawings provide specific example embodiments and implementations. However, the described subject matter can be embodied in a variety of different forms, and therefore, the covered or claimed subject matter is intended to be construed as not being limited to any of the example embodiments set forth herein. The claimed or covered subject matter is intended to be reasonably broad. Among other things, the subject matter can be embodied as a method, apparatus, component, system, or non-transitory computer-readable medium for storing computer code. Thus, embodiments can take the form of, for example, hardware, software, firmware, storage media, or any combination thereof. For example, a component, apparatus, or system including a memory and a processor can implement the above-described method embodiments by executing computer code stored in the memory.

[0299] Throughout the specification and claims, terms may have subtle meanings implied or implied in the context rather than explicitly stated meanings. Similarly, the phrase "in one embodiment / implementation" as used herein does not necessarily refer to the same embodiment, and the phrase "in another embodiment / implementation" as used herein does not necessarily refer to a different embodiment. For example, it is intended that the claimed subject matter encompasses combinations of all or some of the exemplary embodiments.

[0300] Generally, at least part of a term can be understood based on its usage in the context. For example, terms used herein, such as “and,” “or,” or “and / or,” can have multiple meanings, which depend at least in part on the context in which they are used. Typically, “or,” when used in an associative list, such as A, B, or C, is intended to mean A, B, and C (in an inclusive sense) and A, B, or C (in an exclusive sense). Furthermore, the term “one or more,” as used herein, depends at least in part on the context and can be used to describe any feature, structure, or characteristic in a singular sense, or a combination of features, structures, or characteristics in a plural sense. Similarly, the terms “a,” “an,” or “the” can be understood to convey either a singular or a plural usage, depending at least in part on the context. Moreover, the term “based on” can be understood to not necessarily convey an exclusive set of factors, and conversely, may allow for the presence of other factors that are not necessarily explicitly described, which also depends at least in part on the context.

[0301] The use of terms like "features," "advantages," or similar language throughout this specification does not imply that all features and advantages achievable with this solution should be included or contained in any single implementation. Rather, references to features and advantages are understood to indicate that a particular feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of this solution. Therefore, discussions of features and advantages throughout the specification, as well as similar language, may, but are not necessarily, refer to the same embodiments.

[0302] Furthermore, the features, advantages, and characteristics described herein can be combined in any suitable manner in one or more embodiments. Based on the description herein, those skilled in the art will recognize that this solution can be practiced without one or more specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of this solution.

Claims

1. A method performed by a wireless device for preparing a serving cell change procedure, the method comprising: receiving, from a wireless communication node, a measurement and measurement reporting configuration; performing measurements based on the measurement and measurement reporting configuration to generate a measurement report associated with the measurements; and transmitting the measurement report in a measurement reporting message according to the measurement and measurement reporting configuration, the measurement reporting message comprising a layer-1 or layer-2 control message; wherein: the measurement and measurement reporting configuration indicates a triggering event condition for triggering the measurement report, the triggering event condition comprising a difference between a first result of the measurements for at least one candidate cell of a source serving cell of the wireless device and a second result of the measurements for the source serving cell being at or above a measurement gap threshold level; and the measurement gap threshold level comprises a sum of a pre-configured baseline gap threshold level and a configurable tolerance gap threshold level offset.

2. The method of claim 1, wherein: the layer-1 comprises a physical, PHY, layer; and the layer-2 comprises at least one of a medium access control, MAC, layer, a radio link control, RLC, layer, or a packet data convergence protocol, PDCP, layer.

3. The method of claim 1, wherein transmitting the measurement report comprises: the measurements are reported via a layer-1 uplink control information, UCI, message or a layer-2 MAC control element, MAC CE, message.

4. The method of claim 1, wherein the measurement report comprises: measurement results for a source serving cell of the wireless device and at least one or more candidate cells of the source serving cell.

5. The method of claim 1, further comprising: one or more suitable candidate serving cells are identified in a set of candidate neighboring cells for the source serving cell of the wireless device according to performing the cell measurements, wherein the measurement report comprises physical cell information for the one or more suitable candidate cells.

6. The method of claim 5, wherein: the measurement report further comprises beam information for the one or more suitable candidate cells; and the beam information is provided to indicate one or more recommended beams in the one or more suitable candidate cells for the serving cell change procedure.

7. The method of claim 1, wherein the triggering event condition comprises a difference between the first result of the measurements for at least one candidate cell of the source serving cell of the wireless device and a second result of the measurements for the source serving cell being at or above a measurement gap threshold level continuously N times, N being a configurable or pre-defined integer.

8. The method of claim 1, wherein the first result or the second result comprises at least one of a reference signal received power, RSRP, a signal to interference and noise ratio, SINR, or a reference signal received quality, RSRQ.

9. The method of claim 1, wherein the first result and the second result each comprise: cell level measurement results or beam level measurement results associated with the source serving cell of the wireless device and the at least one neighboring cell of the source serving cell, respectively.

10. The method of claim 9, wherein the cell level measurement results for a serving cell are derived from measurements of a plurality of beams associated with the serving cell.

11. The method of claim 9, wherein the beam-level measurement results include measurement results associated with a predetermined number of optimal beams for the source serving cell of the wireless device or the at least one suitable neighboring cell of the source serving cell.

12. The method according to claim 1, wherein: The first result includes N consecutive cell measurements for the first merging performed by the wireless device on the source serving cell, where N is a pre-configured positive integer; as well as The second result includes N consecutive cell measurements of a second merge performed on at least one neighboring cell of the source serving cell.

13. The method of claim 1, wherein sending the measurement report in the measurement reporting message includes, when the triggering event condition is met: Send a MAC CE message including the measurement report to the wireless communication node; or The wireless device is triggered to send the measurement reporting message as Layer-1 uplink control information (UCI) to the wireless communication node.

14. The method of claim 7, wherein the triggering event condition is configured for each serving cell or for a list of candidate serving cells.

15. The method of claim 4, wherein the first neighboring cell and the second neighboring cell of the at least one neighboring cell of the source serving cell are independently configured with different triggering event conditions.

16. A wireless device including a processor and a memory, wherein the processor is configured to read computer code from the memory to cause the wireless device to: Receive measurement and measurement reporting configuration from the wireless communication node; Measurements are performed based on the measurement and measurement reporting configuration to generate a measurement report associated with the measurement; as well as According to the measurement and measurement reporting configuration, the measurement report is sent in the measurement reporting message, which includes a layer-1 or layer-2 control message; in, The measurement and measurement reporting configuration indicates triggering event conditions for triggering the measurement report, the triggering event conditions including a persistent difference between a first result of the measurement of at least one candidate cell of the source serving cell of the wireless device and a second result of the measurement of the source serving cell at or above a measurement gap threshold level; and The measurement gap threshold level includes the sum of the pre-configured baseline gap threshold level and the offset of the configurable tolerance gap threshold level.

17. A computer program product comprising a non-transitory computer-readable program medium having computer code stored thereon, the computer code, when executed by a processor of a wireless device, causing the wireless device to: Receive measurement and measurement reporting configuration from the wireless communication node; Measurements are performed based on the measurement and measurement reporting configuration to generate a measurement report associated with the measurement; as well as According to the measurement and measurement reporting configuration, the measurement report is sent in the measurement reporting message, which includes a layer-1 or layer-2 control message; as well as in, The measurement and measurement reporting configuration indicates triggering event conditions for triggering the measurement report, the triggering event conditions including a persistent difference between a first result of the measurement of at least one candidate cell of the source serving cell of the wireless device and a second result of the measurement of the source serving cell at or above a measurement gap threshold level; and The measurement gap threshold level includes the sum of the pre-configured baseline gap threshold level and the offset of the configurable tolerance gap threshold level.

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