WO2024072131A1

WO2024072131A1 - Selective serving cell configuration for mobility

Info

Publication number: WO2024072131A1
Application number: PCT/KR2023/015088
Authority: WO
Inventors: Sunghoon Jung; Sangwon Kim; Hongsuk Kim
Original assignee: Lg Electronics Inc.
Priority date: 2022-09-29
Filing date: 2023-09-27
Publication date: 2024-04-04

Abstract

The present disclosure relates to selective serving cell configuration for mobility in wireless communications. According to an embodiment of the present disclosure, a method performed by a user equipment (UE) in a wireless communication system comprises: receiving, from a network, a cell configuration pool comprising a plurality of cell configurations for multiple candidate cells, wherein each of the plurality of cell configurations comprises at least one of: a special cell (SpCell) configuration applied based on a corresponding candidate cell being a special cell; or a secondary cell (SCell) configuration applied based on the corresponding candidate cell being a secondary cell; and based on performing a mobility to a first target cell: applying an SpCell configuration in a cell configuration for the first target cell; and applying an SCell configuration in a cell configuration for an SCell related to the first target cell.

Description

SELECTIVE SERVING CELL CONFIGURATION FOR MOBILITY

The present disclosure relates to selective serving cell configuration for mobility in wireless communications.

3rd Generation Partnership Project (3GPP) Long-Term Evolution (LTE) is a technology for enabling high-speed packet communications. Many schemes have been proposed for the LTE objective including those that aim to reduce user and provider costs, improve service quality, and expand and improve coverage and system capacity. The 3GPP LTE requires reduced cost per bit, increased service availability, flexible use of a frequency band, a simple structure, an open interface, and adequate power consumption of a terminal as an upper-level requirement.

Work has started in International Telecommunication Union (ITU) and 3GPP to develop requirements and specifications for New Radio (NR) systems. 3GPP has to identify and develop the technology components needed for successfully standardizing the new RAT timely satisfying both the urgent market needs, and the more long-term requirements set forth by the ITU Radio communication sector (ITU-R) International Mobile Telecommunications (IMT)-2020 process. Further, the NR should be able to use any spectrum band ranging at least up to 100 GHz that may be made available for wireless communications even in a more distant future.

The NR targets a single technical framework addressing all usage scenarios, requirements and deployment scenarios including enhanced Mobile BroadBand (eMBB), massive Machine Type Communications (mMTC), Ultra-Reliable and Low Latency Communications (URLLC), etc. The NR shall be inherently forward compatible.

In wireless communications, a user equipment (UE) may perform a mobility from a source cell to a target cell. For the mobility, the UE may be configured with one or more cell configurations, and may perform the mobility to a target cell based on applying a cell configuration for the target cell. However, configuring each cell configuration for each of a special cell (SpCell) and optionally one or more secondary cells (SCells) may cause a large signalling overhead.

An aspect of the present disclosure is to provide method and apparatus for selective serving cell configuration for mobility in a wireless communication system.

According to an embodiment of the present disclosure, a method performed by a user equipment (UE) in a wireless communication system comprises: receiving, from a network, a cell configuration pool comprising a plurality of cell configurations for multiple candidate cells, wherein each of the plurality of cell configurations comprises at least one of: a special cell (SpCell) configuration applied based on a corresponding candidate cell being a special cell; or a secondary cell (SCell) configuration applied based on the corresponding candidate cell being a secondary cell; and based on performing a mobility to a first target cell: applying an SpCell configuration in a cell configuration for the first target cell; and applying an SCell configuration in a cell configuration for an SCell related to the first target cell.

According to an embodiment of the present disclosure, a user equipment (UE) configured to operate in a wireless communication system comprises: at least one transceiver; at least one processor; and at least one memory operatively coupled to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations comprising: receiving, from a network, a cell configuration pool comprising a plurality of cell configurations for multiple candidate cells, wherein each of the plurality of cell configurations comprises at least one of: a special cell (SpCell) configuration applied based on a corresponding candidate cell being a special cell; or a secondary cell (SCell) configuration applied based on the corresponding candidate cell being a secondary cell; and based on performing a mobility to a first target cell: applying an SpCell configuration in a cell configuration for the first target cell; and applying an SCell configuration in a cell configuration for an SCell related to the first target cell.

According to an embodiment of the present disclosure, a network node configured to operate in a wireless communication system comprises: at least one transceiver; at least one processor; and at least one memory operatively coupled to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations comprising: transmitting, to a user equipment (UE), a cell configuration pool comprising a plurality of cell configurations for multiple candidate cells, wherein each of the plurality of cell configurations comprises at least one of: a special cell (SpCell) configuration applied based on a corresponding candidate cell being a special cell; or a secondary cell (SCell) configuration applied based on the corresponding candidate cell being a secondary cell; and transmitting, to the UE, reference signals related to the multiple candidate cells for a mobility to a target cell among the multiple candidate cells, wherein the UE is configured to, based on performing a mobility to a first target cell: apply an SpCell configuration in a cell configuration for the target cell; and apply an SCell configuration in a cell configuration for an SCell related to the target cell.

According to an embodiment of the present disclosure, a method performed by a network node configured to operate in a wireless communication system comprises: transmitting, to a user equipment (UE), a cell configuration pool comprising a plurality of cell configurations for multiple candidate cells, wherein each of the plurality of cell configurations comprises at least one of: a special cell (SpCell) configuration applied based on a corresponding candidate cell being a special cell; or a secondary cell (SCell) configuration applied based on the corresponding candidate cell being a secondary cell; and transmitting, to the UE, reference signals related to the multiple candidate cells for a mobility to a target cell among the multiple candidate cells, wherein the UE is configured to, based on performing a mobility to a first target cell: apply an SpCell configuration in a cell configuration for the target cell; and apply an SCell configuration in a cell configuration for an SCell related to the target cell.

According to an embodiment of the present disclosure, an apparatus adapted to operate in a wireless communication system comprises: at least processor; and at least one memory operatively coupled to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations comprising: receiving, from a network, a cell configuration pool comprising a plurality of cell configurations for multiple candidate cells, wherein each of the plurality of cell configurations comprises at least one of: a special cell (SpCell) configuration applied based on a corresponding candidate cell being a special cell; or a secondary cell (SCell) configuration applied based on the corresponding candidate cell being a secondary cell; and based on performing a mobility to a first target cell: applying an SpCell configuration in a cell configuration for the first target cell; and applying an SCell configuration in a cell configuration for an SCell related to the first target cell.

According to an embodiment of the present disclosure, a non-transitory computer readable medium (CRM) has stored thereon a program code implementing instructions that, based on being executed by at least one processor, perform operations comprising: receiving, from a network, a cell configuration pool comprising a plurality of cell configurations for multiple candidate cells, wherein each of the plurality of cell configurations comprises at least one of: a special cell (SpCell) configuration applied based on a corresponding candidate cell being a special cell; or a secondary cell (SCell) configuration applied based on the corresponding candidate cell being a secondary cell; and based on performing a mobility to a first target cell: applying an SpCell configuration in a cell configuration for the first target cell; and applying an SCell configuration in a cell configuration for an SCell related to the first target cell.

The present disclosure may have various advantageous effects.

For example, UE may be configured with candidate cell configurations with lower signalling overhead.

Advantageous effects which can be obtained through specific embodiments of the present disclosure are not limited to the advantageous effects listed above. For example, there may be a variety of technical effects that a person having ordinary skill in the related art can understand and/or derive from the present disclosure. Accordingly, the specific effects of the present disclosure are not limited to those explicitly described herein, but may include various effects that may be understood or derived from the technical features of the present disclosure.

FIG. 1 shows an example of a communication system to which implementations of the present disclosure is applied.

FIG. 2 shows an example of wireless devices to which implementations of the present disclosure is applied.

FIG. 3 shows an example of UE to which implementations of the present disclosure is applied.

FIGs. 4 and 5 show an example of protocol stacks in a 3GPP based wireless communication system to which implementations of the present disclosure is applied.

FIG. 6 shows a frame structure in a 3GPP based wireless communication system to which implementations of the present disclosure is applied.

FIG. 7 shows a data flow example in the 3GPP NR system to which implementations of the present disclosure is applied.

FIG. 8 shows an example of a legacy handover procedure to which technical features of the present disclosure can be applied.

FIG. 9 shows an example of a conditional handover procedure to which technical features of the present disclosure can be applied.

FIG. 10 shows an example of configuration parameters for cells according to an embodiment of the present disclosure.

FIG. 11 shows an example of configuration parameters for cells before serving cell change according to an embodiment of the present disclosure.

FIG. 12 shows an example of configuration parameters for cells after serving cell change according to an embodiment of the present disclosure.

FIG. 13 shows an example of a method performed by a UE according to an embodiment of the present disclosure.

FIG. 14 show an example of a signal flow between UE and network node according to an embodiment of the present disclosure.

FIG. 15 shows an example of a method for determining serving cell configuration according to an embodiment of the present disclosure.

The following techniques, apparatuses, and systems may be applied to a variety of wireless multiple access systems. Examples of the multiple access systems include a Code Division Multiple Access (CDMA) system, a Frequency Division Multiple Access (FDMA) system, a Time Division Multiple Access (TDMA) system, an Orthogonal Frequency Division Multiple Access (OFDMA) system, a Single Carrier Frequency Division Multiple Access (SC-FDMA) system, and a Multi Carrier Frequency Division Multiple Access (MC-FDMA) system. CDMA may be embodied through radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may be embodied through radio technology such as Global System for Mobile communications (GSM), General Packet Radio Service (GPRS), or Enhanced Data rates for GSM Evolution (EDGE). OFDMA may be embodied through radio technology such as Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, or Evolved UTRA (E-UTRA). UTRA is a part of a Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) Long-Term Evolution (LTE) is a part of Evolved UMTS (E-UMTS) using E-UTRA. 3GPP LTE employs OFDMA in downlink (DL) and SC-FDMA in uplink (UL). Evolution of 3GPP LTE includes LTE-Advanced (LTE-A), LTE-A Pro, and/or 5G New Radio (NR).

For convenience of description, implementations of the present disclosure are mainly described in regards to a 3GPP based wireless communication system. However, the technical features of the present disclosure are not limited thereto. For example, although the following detailed description is given based on a mobile communication system corresponding to a 3GPP based wireless communication system, aspects of the present disclosure that are not limited to 3GPP based wireless communication system are applicable to other mobile communication systems.

For terms and technologies which are not specifically described among the terms of and technologies employed in the present disclosure, the wireless communication standard documents published before the present disclosure may be referenced.

In the present disclosure, "A or B" may mean "only A", "only B", or "both A and B". In other words, "A or B" in the present disclosure may be interpreted as "A and/or B". For example, "A, B or C" in the present disclosure may mean "only A", "only B", "only C", or "any combination of A, B and C".

In the present disclosure, slash (/) or comma (,) may mean "and/or". For example, "A/B" may mean "A and/or B". Accordingly, "A/B" may mean "only A", "only B", or "both A and B". For example, "A, B, C" may mean "A, B or C".

In the present disclosure, "at least one of A and B" may mean "only A", "only B" or "both A and B". In addition, the expression "at least one of A or B" or "at least one of A and/or B" in the present disclosure may be interpreted as same as "at least one of A and B".

In addition, in the present disclosure, "at least one of A, B and C" may mean "only A", "only B", "only C", or "any combination of A, B and C". In addition, "at least one of A, B or C" or "at least one of A, B and/or C" may mean "at least one of A, B and C".

Also, parentheses used in the present disclosure may mean "for example". In detail, when it is shown as "control information (PDCCH)", "PDCCH" may be proposed as an example of "control information". In other words, "control information" in the present disclosure is not limited to "PDCCH", and "PDCCH" may be proposed as an example of "control information". In addition, even when shown as "control information (i.e., PDCCH)", "PDCCH" may be proposed as an example of "control information".

Technical features that are separately described in one drawing in the present disclosure may be implemented separately or simultaneously.

Although not limited thereto, various descriptions, functions, procedures, suggestions, methods and/or operational flowcharts of the present disclosure disclosed herein can be applied to various fields requiring wireless communication and/or connection (e.g., 5G) between devices.

Hereinafter, the present disclosure will be described in more detail with reference to drawings. The same reference numerals in the following drawings and/or descriptions may refer to the same and/or corresponding hardware blocks, software blocks, and/or functional blocks unless otherwise indicated.

The 5G usage scenarios shown in FIG. 1 are only exemplary, and the technical features of the present disclosure can be applied to other 5G usage scenarios which are not shown in FIG. 1.

Three main requirement categories for 5G include (1) a category of enhanced Mobile BroadBand (eMBB), (2) a category of massive Machine Type Communication (mMTC), and (3) a category of Ultra-Reliable and Low Latency Communications (URLLC).

Referring to FIG. 1, the communication system 1 includes wireless devices 100a to 100f, Base Stations (BSs) 200, and a network 300. Although FIG. 1 illustrates a 5G network as an example of the network of the communication system 1, the implementations of the present disclosure are not limited to the 5G system, and can be applied to the future communication system beyond the 5G system.

The BSs 200 and the network 300 may be implemented as wireless devices and a specific wireless device may operate as a BS/network node with respect to other wireless devices.

The wireless devices 100a to 100f represent devices performing communication using Radio Access Technology (RAT) (e.g., 5G NR or LTE) and may be referred to as communication/radio/5G devices. The wireless devices 100a to 100f may include, without being limited to, a robot 100a, vehicles 100b-1 and 100b-2, an eXtended Reality (XR) device 100c, a hand-held device 100d, a home appliance 100e, an Internet-of-Things (IoT) device 100f, and an Artificial Intelligence (AI) device/server 400. For example, the vehicles may include a vehicle having a wireless communication function, an autonomous driving vehicle, and a vehicle capable of performing communication between vehicles. The vehicles may include an Unmanned Aerial Vehicle (UAV) (e.g., a drone). The XR device may include an Augmented Reality (AR)/Virtual Reality (VR)/Mixed Reality (MR) device and may be implemented in the form of a Head-Mounted Device (HMD), a Head-Up Display (HUD) mounted in a vehicle, a television, a smartphone, a computer, a wearable device, a home appliance device, a digital signage, a vehicle, a robot, etc. The hand-held device may include a smartphone, a smartpad, a wearable device (e.g., a smartwatch or a smartglasses), and a computer (e.g., a notebook). The home appliance may include a TV, a refrigerator, and a washing machine. The IoT device may include a sensor and a smartmeter.

In the present disclosure, the wireless devices 100a to 100f may be called User Equipments (UEs). A UE may include, for example, a cellular phone, a smartphone, a laptop computer, a digital broadcast terminal, a Personal Digital Assistant (PDA), a Portable Multimedia Player (PMP), a navigation system, a slate Personal Computer (PC), a tablet PC, an ultrabook, a vehicle, a vehicle having an autonomous traveling function, a connected car, an UAV, an AI module, a robot, an AR device, a VR device, an MR device, a hologram device, a public safety device, an MTC device, an IoT device, a medical device, a FinTech device (or a financial device), a security device, a weather/environment device, a device related to a 5G service, or a device related to a fourth industrial revolution field.

The wireless devices 100a to 100f may be connected to the network 300 via the BSs 200. An AI technology may be applied to the wireless devices 100a to 100f and the wireless devices 100a to 100f may be connected to the AI server 400 via the network 300. The network 300 may be configured using a 3G network, a 4G (e.g., LTE) network, a 5G (e.g., NR) network, and a beyond-5G network. Although the wireless devices 100a to 100f may communicate with each other through the BSs 200/network 300, the wireless devices 100a to 100f may perform direct communication (e.g., sidelink communication) with each other without passing through the BSs 200/network 300. For example, the vehicles 100b-1 and 100b-2 may perform direct communication (e.g., Vehicle-to-Vehicle (V2V)/Vehicle-to-everything (V2X) communication). The IoT device (e.g., a sensor) may perform direct communication with other IoT devices (e.g., sensors) or other wireless devices 100a to 100f.

Wireless communication/

connections

150a, 150b and 150c may be established between the wireless devices 100a to 100f and/or between wireless device 100a to 100f and BS 200 and/or between BSs 200. Herein, the wireless communication/connections may be established through various RATs (e.g., 5G NR) such as uplink/downlink communication 150a, sidelink communication (or Device-to-Device (D2D) communication) 150b, inter-base station communication 150c (e.g., relay, Integrated Access and Backhaul (IAB)), etc. The wireless devices 100a to 100f and the BSs 200/the wireless devices 100a to 100f may transmit/receive radio signals to/from each other through the wireless communication/

connections

150a, 150b and 150c. For example, the wireless communication/

connections

150a, 150b and 150c may transmit/receive signals through various physical channels. To this end, at least a part of various configuration information configuring processes, various signal processing processes (e.g., channel encoding/decoding, modulation/demodulation, and resource mapping/de-mapping), and resource allocating processes, for transmitting/receiving radio signals, may be performed based on the various proposals of the present disclosure.

NR supports multiples numerologies (and/or multiple Sub-Carrier Spacings (SCS)) to support various 5G services. For example, if SCS is 15 kHz, wide area can be supported in traditional cellular bands, and if SCS is 30 kHz/60 kHz, dense-urban, lower latency, and wider carrier bandwidth can be supported. If SCS is 60 kHz or higher, bandwidths greater than 24.25 GHz can be supported to overcome phase noise.

The NR frequency band may be defined as two types of frequency range, i.e., Frequency Range 1 (FR1) and Frequency Range 2 (FR2). The numerical value of the frequency range may be changed. For example, the frequency ranges of the two types (FR1 and FR2) may be as shown in Table 1 below. For ease of explanation, in the frequency ranges used in the NR system, FR1 may mean "sub 6 GHz range", FR2 may mean "above 6 GHz range," and may be referred to as millimeter Wave (mmW).

Frequency Range designation	Corresponding frequency range	Subcarrier Spacing
FR1	450MHz - 6000MHz	15, 30, 60kHz
FR2	24250MHz - 52600MHz	60, 120, 240kHz

As mentioned above, the numerical value of the frequency range of the NR system may be changed. For example, FR1 may include a frequency band of 410MHz to 7125MHz as shown in Table 2 below. That is, FR1 may include a frequency band of 6GHz (or 5850, 5900, 5925 MHz, etc.) or more. For example, a frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or more included in FR1 may include an unlicensed band. Unlicensed bands may be used for a variety of purposes, for example for communication for vehicles (e.g., autonomous driving).

Frequency Range designation	Corresponding frequency range	Subcarrier Spacing
FR1	410MHz - 7125MHz	15, 30, 60kHz
FR2	24250MHz - 52600MHz	60, 120, 240kHz

Here, the radio communication technologies implemented in the wireless devices in the present disclosure may include NarrowBand IoT (NB-IoT) technology for low-power communication as well as LTE, NR and 6G. For example, NB-IoT technology may be an example of Low Power Wide Area Network (LPWAN) technology, may be implemented in specifications such as LTE Cat NB1 and/or LTE Cat NB2, and may not be limited to the above-mentioned names. Additionally and/or alternatively, the radio communication technologies implemented in the wireless devices in the present disclosure may communicate based on LTE-M technology. For example, LTE-M technology may be an example of LPWAN technology and be called by various names such as enhanced MTC (eMTC). For example, LTE-M technology may be implemented in at least one of the various specifications, such as 1) LTE Cat 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-bandwidth limited (non-BL), 5) LTE-MTC, 6) LTE Machine Type Communication, and/or 7) LTE M, and may not be limited to the above-mentioned names. Additionally and/or alternatively, the radio communication technologies implemented in the wireless devices in the present disclosure may include at least one of ZigBee, Bluetooth, and/or LPWAN which take into account low-power communication, and may not be limited to the above-mentioned names. For example, ZigBee technology may generate Personal Area Networks (PANs) associated with small/low-power digital communication based on various specifications such as IEEE 802.15.4 and may be called various names.FIG. 2 shows an example of wireless devices to which implementations of the present disclosure is applied.

In FIG. 2, The first wireless device 100 and/or the second wireless device 200 may be implemented in various forms according to use cases/services. For example, {the first wireless device 100 and the second wireless device 200} may correspond to at least one of {the wireless device 100a to 100f and the BS 200}, {the wireless device 100a to 100f and the wireless device 100a to 100f} and/or {the BS 200 and the BS 200} of FIG. 1. The first wireless device 100 and/or the second wireless device 200 may be configured by various elements, devices/parts, and/or modules.

The first wireless device 100 may include at least one transceiver, such as a transceiver 106, at least one processing chip, such as a processing chip 101, and/or one or more antennas 108.

The processing chip 101 may include at least one processor, such a processor 102, and at least one memory, such as a memory 104. Additional and/or alternatively, the memory 104 may be placed outside of the processing chip 101.

The processor 102 may control the memory 104 and/or the transceiver 106 and may be adapted to implement the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts described in the present disclosure. For example, the processor 102 may process information within the memory 104 to generate first information/signals and then transmit radio signals including the first information/signals through the transceiver 106. The processor 102 may receive radio signals including second information/signals through the transceiver 106 and then store information obtained by processing the second information/signals in the memory 104.

The memory 104 may be operably connectable to the processor 102. The memory 104 may store various types of information and/or instructions. The memory 104 may store a firmware and/or a software code 105 which implements codes, commands, and/or a set of commands that, when executed by the processor 102, perform the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. For example, the firmware and/or the software code 105 may implement instructions that, when executed by the processor 102, perform the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. For example, the firmware and/or the software code 105 may control the processor 102 to perform one or more protocols. For example, the firmware and/or the software code 105 may control the processor 102 to perform one or more layers of the radio interface protocol.

Herein, the processor 102 and the memory 104 may be a part of a communication modem/circuit/chip designed to implement RAT (e.g., LTE or NR). The transceiver 106 may be connected to the processor 102 and transmit and/or receive radio signals through one or more antennas 108. Each of the transceiver 106 may include a transmitter and/or a receiver. The transceiver 106 may be interchangeably used with Radio Frequency (RF) unit(s). In the present disclosure, the first wireless device 100 may represent a communication modem/circuit/chip.

The second wireless device 200 may include at least one transceiver, such as a transceiver 206, at least one processing chip, such as a processing chip 201, and/or one or more antennas 208.

The processing chip 201 may include at least one processor, such a processor 202, and at least one memory, such as a memory 204. Additional and/or alternatively, the memory 204 may be placed outside of the processing chip 201.

The processor 202 may control the memory 204 and/or the transceiver 206 and may be adapted to implement the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts described in the present disclosure. For example, the processor 202 may process information within the memory 204 to generate third information/signals and then transmit radio signals including the third information/signals through the transceiver 206. The processor 202 may receive radio signals including fourth information/signals through the transceiver 106 and then store information obtained by processing the fourth information/signals in the memory 204.

The memory 204 may be operably connectable to the processor 202. The memory 204 may store various types of information and/or instructions. The memory 204 may store a firmware and/or a software code 205 which implements codes, commands, and/or a set of commands that, when executed by the processor 202, perform the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. For example, the firmware and/or the software code 205 may implement instructions that, when executed by the processor 202, perform the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. For example, the firmware and/or the software code 205 may control the processor 202 to perform one or more protocols. For example, the firmware and/or the software code 205 may control the processor 202 to perform one or more layers of the radio interface protocol.

Herein, the processor 202 and the memory 204 may be a part of a communication modem/circuit/chip designed to implement RAT (e.g., LTE or NR). The transceiver 206 may be connected to the processor 202 and transmit and/or receive radio signals through one or more antennas 208. Each of the transceiver 206 may include a transmitter and/or a receiver. The transceiver 206 may be interchangeably used with RF unit. In the present disclosure, the second wireless device 200 may represent a communication modem/circuit/chip.

Hereinafter, hardware elements of the

wireless devices

100 and 200 will be described more specifically. One or more protocol layers may be implemented by, without being limited to, one or

more processors

102 and 202. For example, the one or

more processors

102 and 202 may implement one or more layers (e.g., functional layers such as Physical (PHY) layer, Media Access Control (MAC) layer, Radio Link Control (RLC) layer, Packet Data Convergence Protocol (PDCP) layer, Radio Resource Control (RRC) layer, and Service Data Adaptation Protocol (SDAP) layer). The one or

more processors

102 and 202 may generate one or more Protocol Data Units (PDUs), one or more Service Data Unit (SDUs), messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. The one or

more processors

102 and 202 may generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure and provide the generated signals to the one or

more transceivers

106 and 206. The one or

more processors

102 and 202 may receive the signals (e.g., baseband signals) from the one or

more transceivers

106 and 206 and acquire the PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure.

The one or

more processors

102 and 202 may be referred to as controllers, microcontrollers, microprocessors, or microcomputers. The one or

more processors

102 and 202 may be implemented by hardware, firmware, software, or a combination thereof. As an example, one or more Application Specific Integrated Circuits (ASICs), one or more Digital Signal Processors (DSPs), one or more Digital Signal Processing Devices (DSPDs), one or more Programmable Logic Devices (PLDs), or one or more Field Programmable Gate Arrays (FPGAs) may be included in the one or

more processors

102 and 202. For example, the one or

more processors

102 and 202 may be configured by a set of a communication control processor, an Application Processor (AP), an Electronic Control Unit (ECU), a Central Processing Unit (CPU), a Graphic Processing Unit (GPU), and a memory control processor.

The one or

more memories

104 and 204 may be connected to the one or

more processors

102 and 202 and store various types of data, signals, messages, information, programs, code, instructions, and/or commands. The one or

more memories

104 and 204 may be configured by Random Access Memory (RAM), Dynamic RAM (DRAM), Read-Only Memory (ROM), electrically Erasable Programmable Read-Only Memory (EPROM), flash memory, volatile memory, non-volatile memory, hard drive, register, cash memory, computer-readable storage medium, and/or combinations thereof. The one or

more memories

104 and 204 may be located at the interior and/or exterior of the one or

more processors

102 and 202. The one or

more memories

104 and 204 may be connected to the one or

more processors

102 and 202 through various technologies such as wired or wireless connection.

The one or

more transceivers

106 and 206 may transmit user data, control information, and/or radio signals/channels, mentioned in the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure, to one or more other devices. The one or

more transceivers

106 and 206 may receive user data, control information, and/or radio signals/channels, mentioned in the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure, from one or more other devices. For example, the one or

more transceivers

106 and 206 may be connected to the one or

more processors

102 and 202 and transmit and receive radio signals. For example, the one or

more processors

102 and 202 may perform control so that the one or

more transceivers

106 and 206 may transmit user data, control information, or radio signals to one or more other devices. The one or

more processors

102 and 202 may perform control so that the one or

more transceivers

106 and 206 may receive user data, control information, or radio signals from one or more other devices.

The one or

more transceivers

106 and 206 may be connected to the one or more antennas 108 and 208. Additionally and/or alternatively, the one or

more transceivers

106 and 206 may include one or more antennas 108 and 208. The one or

more transceivers

106 and 206 may be adapted to transmit and receive user data, control information, and/or radio signals/channels, mentioned in the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure, through the one or more antennas 108 and 208. In the present disclosure, the one or more antennas 108 and 208 may be a plurality of physical antennas or a plurality of logical antennas (e.g., antenna ports).

The one or

more transceivers

106 and 206 may convert received user data, control information, radio signals/channels, etc., from RF band signals into baseband signals in order to process received user data, control information, radio signals/channels, etc., using the one or

more processors

102 and 202. The one or

more transceivers

106 and 206 may convert the user data, control information, radio signals/channels, etc., processed using the one or

more processors

102 and 202 from the base band signals into the RF band signals. To this end, the one or

more transceivers

106 and 206 may include (analog) oscillators and/or filters. For example, the one or

more transceivers

106 and 206 can up-convert OFDM baseband signals to OFDM signals by their (analog) oscillators and/or filters under the control of the one or

more processors

102 and 202 and transmit the up-converted OFDM signals at the carrier frequency. The one or

more transceivers

106 and 206 may receive OFDM signals at a carrier frequency and down-convert the OFDM signals into OFDM baseband signals by their (analog) oscillators and/or filters under the control of the one or

more processors

102 and 202.

Although not shown in FIG. 2, the

wireless devices

100 and 200 may further include additional components. The additional components 140 may be variously configured according to types of the

wireless devices

100 and 200. For example, the additional components 140 may include at least one of a power unit/battery, an Input/Output (I/O) device (e.g., audio I/O port, video I/O port), a driving device, and a computing device. The additional components 140 may be coupled to the one or

more processors

102 and 202 via various technologies, such as a wired or wireless connection.

In the implementations of the present disclosure, a UE may operate as a transmitting device in Uplink (UL) and as a receiving device in Downlink (DL). In the implementations of the present disclosure, a BS may operate as a receiving device in UL and as a transmitting device in DL. Hereinafter, for convenience of description, it is mainly assumed that the first wireless device 100 acts as the UE, and the second wireless device 200 acts as the BS. For example, the processor(s) 102 connected to, mounted on or launched in the first wireless device 100 may be adapted to perform the UE behavior according to an implementation of the present disclosure or control the transceiver(s) 106 to perform the UE behavior according to an implementation of the present disclosure. The processor(s) 202 connected to, mounted on or launched in the second wireless device 200 may be adapted to perform the BS behavior according to an implementation of the present disclosure or control the transceiver(s) 206 to perform the BS behavior according to an implementation of the present disclosure.

In the present disclosure, a BS is also referred to as a node B (NB), an eNode B (eNB), or a gNB.

Referring to FIG. 3, a UE 100 may correspond to the first wireless device 100 of FIG. 2.

A UE 100 includes a processor 102, a memory 104, a transceiver 106, one or more antennas 108, a power management module 141, a battery 142, a display 143, a keypad 144, a Subscriber Identification Module (SIM) card 145, a speaker 146, and a microphone 147.

The processor 102 may be adapted to implement the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. The processor 102 may be adapted to control one or more other components of the UE 100 to implement the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. Layers of the radio interface protocol may be implemented in the processor 102. The processor 102 may include ASIC, other chipset, logic circuit and/or data processing device. The processor 102 may be an application processor. The processor 102 may include at least one of DSP, CPU, GPU, a modem (modulator and demodulator). An example of the processor 102 may be found in SNAPDRAGON^TM series of processors made by Qualcomm^®, EXYNOS^TM series of processors made by Samsung^®, A series of processors made by Apple^®, HELIO^TM series of processors made by MediaTek^®, ATOM^TM series of processors made by Intel^® or a corresponding next generation processor.

The memory 104 is operatively coupled with the processor 102 and stores a variety of information to operate the processor 102. The memory 104 may include ROM, RAM, flash memory, memory card, storage medium and/or other storage device. When the embodiments are implemented in software, the techniques described herein can be implemented with modules (e.g., procedures, functions, etc.) that perform the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. The modules can be stored in the memory 104 and executed by the processor 102. The memory 104 can be implemented within the processor 102 or external to the processor 102 in which case those can be communicatively coupled to the processor 102 via various means as is known in the art.

The transceiver 106 is operatively coupled with the processor 102, and transmits and/or receives a radio signal. The transceiver 106 includes a transmitter and a receiver. The transceiver 106 may include baseband circuitry to process radio frequency signals. The transceiver 106 controls the one or more antennas 108 to transmit and/or receive a radio signal.

The power management module 141 manages power for the processor 102 and/or the transceiver 106. The battery 142 supplies power to the power management module 141.

The display 143 outputs results processed by the processor 102. The keypad 144 receives inputs to be used by the processor 102. The keypad 144 may be shown on the display 143.

The SIM card 145 is an　integrated circuit　that is intended to　securely store the　International Mobile Subscriber Identity　(IMSI) number and its related　key, which are used to identify and authenticate subscribers on　mobile telephony　devices (such as　mobile phones　and　computers). It is also possible to store contact information on many SIM cards.

The speaker 146 outputs sound-related results processed by the processor 102. The microphone 147 receives sound-related inputs to be used by the processor 102.

In particular, FIG. 4 illustrates an example of a radio interface user plane protocol stack between a UE and a BS and FIG. 5 illustrates an example of a radio interface control plane protocol stack between a UE and a BS. The control plane refers to a path through which control messages used to manage call by a UE and a network are transported. The user plane refers to a path through which data generated in an application layer, for example, voice data or Internet packet data are transported. Referring to FIG. 4, the user plane protocol stack may be divided into Layer 1 (i.e., a PHY layer) and Layer 2. Referring to FIG. 5, the control plane protocol stack may be divided into Layer 1 (i.e., a PHY layer), Layer 2, Layer 3 (e.g., an RRC layer), and a non-access stratum (NAS) layer. Layer 1, Layer 2 and Layer 3 are referred to as an access stratum (AS).

In the 3GPP LTE system, the Layer 2 is split into the following sublayers: MAC, RLC, and PDCP. In the 3GPP NR system, the Layer 2 is split into the following sublayers: MAC, RLC, PDCP and SDAP. The PHY layer offers to the MAC sublayer transport channels, the MAC sublayer offers to the RLC sublayer logical channels, the RLC sublayer offers to the PDCP sublayer RLC channels, the PDCP sublayer offers to the SDAP sublayer radio bearers. The SDAP sublayer offers to 5G core network quality of service (QoS) flows.

In the 3GPP NR system, the main services and functions of the MAC sublayer include: mapping between logical channels and transport channels; multiplexing/de-multiplexing of MAC SDUs belonging to one or different logical channels into/from transport blocks (TB) delivered to/from the physical layer on transport channels; scheduling information reporting; error correction through hybrid automatic repeat request (HARQ) (one HARQ entity per cell in case of carrier aggregation (CA)); priority handling between UEs by means of dynamic scheduling; priority handling between logical channels of one UE by means of logical channel prioritization; padding. A single MAC entity may support multiple numerologies, transmission timings and cells. Mapping restrictions in logical channel prioritization control which numerology(ies), cell(s), and transmission timing(s) a logical channel can use.

Different kinds of data transfer services are offered by MAC. To accommodate different kinds of data transfer services, multiple types of logical channels are defined, i.e., each supporting transfer of a particular type of information. Each logical channel type is defined by what type of information is transferred. Logical channels are classified into two groups: control channels and traffic channels. Control channels are used for the transfer of control plane information only, and traffic channels are used for the transfer of user plane information only. Broadcast control channel (BCCH) is a downlink logical channel for broadcasting system control information, paging control channel (PCCH) is a downlink logical channel that transfers paging information, system information change notifications and indications of ongoing public warning service (PWS) broadcasts, common control channel (CCCH) is a logical channel for transmitting control information between UEs and network and used for UEs having no RRC connection with the network, and dedicated control channel (DCCH) is a point-to-point bi-directional logical channel that transmits dedicated control information between a UE and the network and used by UEs having an RRC connection. Dedicated traffic channel (DTCH) is a point-to-point logical channel, dedicated to one UE, for the transfer of user information. A DTCH can exist in both uplink and downlink. In downlink, the following connections between logical channels and transport channels exist: BCCH can be mapped to broadcast channel (BCH); BCCH can be mapped to downlink shared channel (DL-SCH); PCCH can be mapped to paging channel (PCH); CCCH can be mapped to DL-SCH; DCCH can be mapped to DL-SCH; and DTCH can be mapped to DL-SCH. In uplink, the following connections between logical channels and transport channels exist: CCCH can be mapped to uplink shared channel (UL-SCH); DCCH can be mapped to UL-SCH; and DTCH can be mapped to UL-SCH.

The RLC sublayer supports three transmission modes: transparent mode (TM), unacknowledged mode (UM), and acknowledged node (AM). The RLC configuration is per logical channel with no dependency on numerologies and/or transmission durations. In the 3GPP NR system, the main services and functions of the RLC sublayer depend on the transmission mode and include: transfer of upper layer PDUs; sequence numbering independent of the one in PDCP (UM and AM); error correction through ARQ (AM only); segmentation (AM and UM) and re-segmentation (AM only) of RLC SDUs; reassembly of SDU (AM and UM); duplicate detection (AM only); RLC SDU discard (AM and UM); RLC re-establishment; protocol error detection (AM only).

In the 3GPP NR system, the main services and functions of the PDCP sublayer for the user plane include: sequence numbering; header compression and decompression using robust header compression (ROHC); transfer of user data; reordering and duplicate detection; in-order delivery; PDCP PDU routing (in case of split bearers); retransmission of PDCP SDUs; ciphering, deciphering and integrity protection; PDCP SDU discard; PDCP re-establishment and data recovery for RLC AM; PDCP status reporting for RLC AM; duplication of PDCP PDUs and duplicate discard indication to lower layers. The main services and functions of the PDCP sublayer for the control plane include: sequence numbering; ciphering, deciphering and integrity protection; transfer of control plane data; reordering and duplicate detection; in-order delivery; duplication of PDCP PDUs and duplicate discard indication to lower layers.

In the 3GPP NR system, the main services and functions of SDAP include: mapping between a QoS flow and a data radio bearer; marking QoS flow ID (QFI) in both DL and UL packets. A single protocol entity of SDAP is configured for each individual PDU session.

In the 3GPP NR system, the main services and functions of the RRC sublayer include: broadcast of system information related to AS and NAS; paging initiated by 5GC or NG-RAN; establishment, maintenance and release of an RRC connection between the UE and NG-RAN; security functions including key management; establishment, configuration, maintenance and release of signaling radio bearers (SRBs) and data radio bearers (DRBs); mobility functions (including: handover and context transfer, UE cell selection and reselection and control of cell selection and reselection, inter-RAT mobility); QoS management functions; UE measurement reporting and control of the reporting; detection of and recovery from radio link failure; NAS message transfer to/from NAS from/to UE.

The frame structure shown in FIG. 6 is purely exemplary and the number of subframes, the number of slots, and/or the number of symbols in a frame may be variously changed. In the 3GPP based wireless communication system, OFDM numerologies (e.g., subcarrier spacing (SCS), transmission time interval (TTI) duration) may be differently configured between a plurality of cells aggregated for one UE. For example, if a UE is configured with different SCSs for cells aggregated for the cell, an (absolute time) duration of a time resource (e.g., a subframe, a slot, or a TTI) including the same number of symbols may be different among the aggregated cells. Herein, symbols may include OFDM symbols (or CP-OFDM symbols), SC-FDMA symbols (or discrete Fourier transform-spread-OFDM (DFT-s-OFDM) symbols).

Referring to FIG. 6, downlink and uplink transmissions are organized into frames. Each frame has T_f = 10ms duration. Each frame is divided into two half-frames, where each of the half-frames has 5ms duration. Each half-frame consists of 5 subframes, where the duration T_sf per subframe is 1ms. Each subframe is divided into slots and the number of slots in a subframe depends on a subcarrier spacing. Each slot includes 14 or 12 OFDM symbols based on a cyclic prefix (CP). In a normal CP, each slot includes 14 OFDM symbols and, in an extended CP, each slot includes 12 OFDM symbols. The numerology is based on exponentially scalable subcarrier spacing βf = 2^u*15 kHz.

Table 3 shows the number of OFDM symbols per slot N^slot _symb, the number of slots per frame N^frame,u _slot, and the number of slots per subframe N^subframe,u _slot for the normal CP, according to the subcarrier spacing βf = 2^u*15 kHz.

u	N ^slot _symb	N ^frame,u _slot	N ^subframe,u _slot
0	14	10	1
1	14	20	2
2	14	40	4
3	14	80	8
4	14	160	16

Table 4 shows the number of OFDM symbols per slot N^slot _symb, the number of slots per frame N^frame,u _slot, and the number of slots per subframe N^subframe,u _slot for the extended CP, according to the subcarrier spacing βf = 2^u*15 kHz.

u	N ^slot _symb	N ^frame,u _slot	N ^subframe,u _slot
2	12	40	4

A slot includes plural symbols (e.g., 14 or 12 symbols) in the time domain. For each numerology (e.g., subcarrier spacing) and carrier, a resource grid of N ^size,u _grid,x*N ^RB _sc subcarriers and N ^subframe,u _symb OFDM symbols is defined, starting at common resource block (CRB) N ^start,u _grid indicated by higher-layer signaling (e.g., RRC signaling), where N ^size,u _grid,x is the number of resource blocks (RBs) in the resource grid and the subscript x is DL for downlink and UL for uplink. N ^RB _sc is the number of subcarriers per RB. In the 3GPP based wireless communication system, N ^RB _sc is 12 generally. There is one resource grid for a given antenna port p, subcarrier spacing configuration u, and transmission direction (DL or UL). The carrier bandwidth N ^size,u _grid for subcarrier spacing configuration u is given by the higher-layer parameter (e.g., RRC parameter). Each element in the resource grid for the antenna port p and the subcarrier spacing configuration u is referred to as a resource element (RE) and one complex symbol may be mapped to each RE. Each RE in the resource grid is uniquely identified by an index k in the frequency domain and an index l representing a symbol location relative to a reference point in the time domain. In the 3GPP based wireless communication system, an RB is defined by 12 consecutive subcarriers in the frequency domain. As shown in FIG. 6, as SCS doubles, the slot length and symbol length are halved. For example, when SCS is 15kHz, the slot length is 1ms, which is the same as the subframe length. When SCS is 30kHz, the slot length is 0.5ms (=500us), and the symbol length is half of that when the SCS is 15kHz. When SCS is 60kHz, the slot length is 0.25ms (=250us), and the symbol length is half of that when the SCS is 30kHz. When SCS is 120kHz, the slot length is 0.125ms (=125us), and the symbol length is half of that when the SCS is 60kHz. When SCS is 240kHz, the slot length is 0.0625ms (=62.5us), and the symbol length is half of that when the SCS is 120kHz.

In the 3GPP NR system, RBs are classified into CRBs and physical resource blocks (PRBs). CRBs are numbered from 0 and upwards in the frequency domain for subcarrier spacing configuration u. The center of subcarrier 0 of CRB 0 for subcarrier spacing configuration u coincides with 'point A' which serves as a common reference point for resource block grids. In the 3GPP NR system, PRBs are defined within a bandwidth part (BWP) and numbered from 0 to N ^size _BWP,i-1, where i is the number of the bandwidth part. The relation between the physical resource block n_PRB in the bandwidth part i and the common resource block n_CRB is as follows: n_PRB = n_CRB + N ^size _BWP,i, where N ^size _BWP,i is the common resource block where bandwidth part starts relative to CRB 0. The BWP includes a plurality of consecutive RBs. A carrier may include a maximum of N (e.g., 5) BWPs. A UE may be configured with one or more BWPs on a given component carrier. Only one BWP among BWPs configured to the UE can active at a time. The active BWP defines the UE's operating bandwidth within the cell's operating bandwidth.

In the present disclosure, the term "cell" may refer to a geographic area to which one or more nodes provide a communication system, or refer to radio resources. A "cell" as a geographic area may be understood as coverage within which a node can provide service using a carrier and a "cell" as radio resources (e.g., time-frequency resources) is associated with bandwidth which is a frequency range configured by the carrier. The "cell" associated with the radio resources is defined by a combination of downlink resources and uplink resources, for example, a combination of a DL component carrier (CC) and a UL CC. The cell may be configured by downlink resources only, or may be configured by downlink resources and uplink resources. Since DL coverage, which is a range within which the node is capable of transmitting a valid signal, and UL coverage, which is a range within which the node is capable of receiving the valid signal from the UE, depends upon a carrier carrying the signal, the coverage of the node may be associated with coverage of the "cell" of radio resources used by the node. Accordingly, the term "cell" may be used to represent service coverage of the node sometimes, radio resources at other times, or a range that signals using the radio resources can reach with valid strength at other times.

In CA, two or more CCs are aggregated. A UE may simultaneously receive or transmit on one or multiple CCs depending on its capabilities. CA is supported for both contiguous and non-contiguous CCs. When CA is configured, the UE only has one RRC connection with the network. At RRC connection establishment/re-establishment/handover, one serving cell provides the NAS mobility information, and at RRC connection re-establishment/handover, one serving cell provides the security input. This cell is referred to as the primary cell (PCell). The PCell is a cell, operating on the primary frequency, in which the UE either performs the initial connection establishment procedure or initiates the connection re-establishment procedure. Depending on UE capabilities, secondary cells (SCells) can be configured to form together with the PCell a set of serving cells. An SCell is a cell providing additional radio resources on top of special cell (SpCell). The configured set of serving cells for a UE therefore always consists of one PCell and one or more SCells. For dual connectivity (DC) operation, the term SpCell refers to the PCell of the master cell group (MCG) or the primary SCell (PSCell) of the secondary cell group (SCG). An SpCell supports PUCCH transmission and contention-based random access, and is always activated. The MCG is a group of serving cells associated with a master node, comprised of the SpCell (PCell) and optionally one or more SCells. The SCG is the subset of serving cells associated with a secondary node, comprised of the PSCell and zero or more SCells, for a UE configured with DC. For a UE in RRC_CONNECTED not configured with CA/DC, there is only one serving cell comprised of the PCell. For a UE in RRC_CONNECTED configured with CA/DC, the term "serving cells" is used to denote the set of cells comprised of the SpCell(s) and all SCells. In DC, two MAC entities are configured in a UE: one for the MCG and one for the SCG.

Referring to FIG. 7, "RB" denotes a radio bearer, and "H" denotes a header. Radio bearers are categorized into two groups: DRBs for user plane data and SRBs for control plane data. The MAC PDU is transmitted/received using radio resources through the PHY layer to/from an external device. The MAC PDU arrives to the PHY layer in the form of a transport block.

In the PHY layer, the uplink transport channels UL-SCH and RACH are mapped to their physical channels physical uplink shared channel (PUSCH) and physical random access channel (PRACH), respectively, and the downlink transport channels DL-SCH, BCH and PCH are mapped to physical downlink shared channel (PDSCH), physical broadcast channel (PBCH) and PDSCH, respectively. In the PHY layer, uplink control information (UCI) is mapped to physical uplink control channel (PUCCH), and downlink control information (DCI) is mapped to physical downlink control channel (PDCCH). A MAC PDU related to UL-SCH is transmitted by a UE via a PUSCH based on an UL grant, and a MAC PDU related to DL-SCH is transmitted by a BS via a PDSCH based on a DL assignment.

Hereinafter, contents regarding handover (HO) are described.

The handover may comprise PCell change. Further, in the present disclosure, descriptions related to handover may also be applied to other mobility procedures, such as PSCell change (or, secondary node (SN) change) and/or PSCell addition (or, SN addition).

Referring to FIG. 8, in step S801, the source RAN node may transmit measurement control message to the UE. The source RAN node may configure the UE measurement procedures according to the roaming and access restriction information and, for example, the available multiple frequency band information through the measurement control message. Measurement control information provided by the source RAN node through the measurement control message may assist the function controlling the UE's connection mobility. For example, the measurement control message may comprise measurement configuration and/or report configuration.

In step S803, the UE may transmit a measurement report message to the source RAN node. The measurement report message may comprise a result of measurement on neighbor cell(s) around the UE which can be detected by the UE. The UE may generate the measurement report message according to a measurement configuration and/or measurement control information in the measurement control message received in step S801.

In step S805, the source RAN node may make a handover (HO) decision based on the measurement report. For example, the source RAN node may make a HO decision and determine a target RAN node for HO among neighbor cells around the UE based on a result of measurement (e.g., cell quality, signal quality, signal strength, reference signal received power (RSRP), reference signal received quality (RSRP), channel state, channel quality, signal to interference plus noise ratio (SINR)) on the neighbor cells.

In step S807, the source RAN node may transmit a HO request message to the target RAN node which is determined in step S805. That is, the source RAN node may perform handover preparation with the target RAN node. The HO request message may comprise necessary information to prepare the handover at the target RAN node.

In step S809, the target RAN node may perform an admission control based on information included in the HO request message. The target RAN node may configure and reserve the required resources (e.g., C-RNTI and/or RACH preamble). The AS-configuration to be used in the target RAN node can either be specified independently (i.e. an "establishment") or as a delta compared to the AS-configuration used in the source RAN node (i.e. a "reconfiguration").

In step S811, the target RAN node may transmit a HO request acknowledge (ACK) message to the source RAN node. The HO request ACK message may comprise information on resources reserved and prepared for a handover. For example, the HO request ACK message may comprise a transparent container to be sent to the UE as an RRC message to perform the handover. The container may include a new C-RNTI, target gNB security algorithm identifiers for the selected security algorithms, a dedicated RACH preamble, and/or possibly some other parameters i.e. access parameters, SIBs. If RACH-less handover is configured, the container may include timing adjustment indication and optionally a preallocated uplink grant. The HO request ACK message may also include RNL/TNL information for forwarding tunnels, if necessary. As soon as the source RAN node receives the HO request ACK message, or as soon as the transmission of the handover command is initiated in the downlink, data forwarding may be initiated.

In step S813, the source RAN node may transmit a handover command, to the UE. For example, the handover command may comprise or may be a cell configuration (i.e., RRCReconfiguration message including the reconfigurationWithSync). The RRCReconfiguration message and/or reconfigurationWithSync for a target cell may comprise information required to access the target cell (i.e., access configuration) comprising at least one of a physical cell ID of the target cell, identifier of the UE (i.e., C-RNTI), HO validity timer (i.e., T304 timer), the target gNB security algorithm identifiers for the selected security algorithms, a set of dedicated RACH resources for contention-free random access (e.g., dedicated random access preamble), the association between RACH resources and SSB(s), the association between RACH resources and UE-specific CSI-RS configuration(s), common RACH resources, or system information of the target cell. The source RAN node may perform the necessary integrity protection and ciphering of the message.

In step S815, the UE may switch to a new cell i.e., the target RAN node. The UE may detach from the old cell i.e., the source RAN node and synchronize to a new cell i.e., the target RAN node. The UE may perform a handover from the source RAN node to the target RAN node based on applying the cell configuration. For example, upon receiving the handover command, the UE may start the T304 timer, and perform a contention-free random access towards the target RAN node based on the set of dedicated RACH resources.

In step S817, upon successful completion of the random access procedure, the UE may stop the T304 timer, and transmit a handover complete message (i.e., RRCReconfigurationComplete message) to the target RAN node. The UE may send the RRCReconfigurationComplete message comprising the C-RNTI to confirm the handover, to the target RAN node to indicate that the handover procedure is completed for the UE. The target RAN node may verify the C-RNTI sent in the RRCReconfigurationComplete message. The target RAN node can now begin sending data to the UE. When the random access fails and the T304 timer is still running, the UE may retry random access towards the target RAN node. Upon expiry of the T304 timer, the UE may declare handover failure (HOF) and perform an RRC re-establishment procedure.

Referring to FIG. 9, in step S901, the source cell may transmit measurement control message to the UE. The measurement control message may comprise a measurement configuration including a list of measurement configurations, and each measurement configuration in the list includes a measurement identity (ID), the corresponding measurement object and the corresponding report configuration.

In step S903, the UE may transmit a measurement report message to the source cell. The measurement report message may comprise a result of measurement on neighbor cell(s) around the UE which can be detected by the UE. The UE may generate the measurement report message according to a measurement configuration and/or measurement control information in the measurement control message received in step S901.

In step S905, the source cell may make a handover decision based on the measurement report. For example, the source cell may make a handover decision and determine candidate target cells (e.g., target cell 1 and target cell 2) for handover among neighbor cells around the UE based on a result of measurement (e.g., signal quality, reference signal received power (RSRP), reference signal received quality (RSRP)) on the neighbor cells.

In step S907, the source cell may transmit handover request messages to the target cell 1 and the target cell 2 which are determined in step S905. That is, the source cell may perform handover preparation with the target cell 1 and the target cell 2. The handover request message may comprise necessary information to prepare the handover at the target side (e.g., target cell 1 and target cell 2).

In step S909, each of the target cell 1 and the target cell 2 may perform an admission control based on information included in the handover request message. The target cell may configure and reserve the required resources (e.g., C-RNTI and/or RACH preamble). The AS-configuration to be used in the target cell can either be specified independently (i.e. an "establishment") or as a delta compared to the AS-configuration used in the source cell (i.e. a "reconfiguration").

In step S911, the target cell and the target cell 2 may transmit a handover request acknowledge (ACK) message to the source cell. The handover request ACK message may comprise cell configuration (i.e., RRCReconfiguration message including ReconfigurationWithSync) including information on resources reserved and prepared for a handover. For example, the handover request ACK message may comprise a transparent container to be sent to the UE as an RRC message (i.e., RRCReconfiguration message/cell configuration) to perform the handover. The container/cell configuration/RRCReconfiguration message may include information required to access the target cell (i.e., access configuration) comprising at least one of a physical cell ID of the target cell, identifier of the UE (i.e., C-RNTI), HO validity timer (i.e., T304 timer), the target gNB security algorithm identifiers for the selected security algorithms, a set of dedicated RACH resources for contention-free random access (e.g., dedicated random access preamble), the association between RACH resources and SSB(s), the association between RACH resources and UE-specific CSI-RS configuration(s), common RACH resources, or system information of the target cell. If RACH-less handover is configured, the container may include timing adjustment indication and optionally a pre-allocated uplink grant. The handover request ACK message may also include RNL/TNL information for forwarding tunnels, if necessary. As soon as the source cell receives the handover request ACK message, or as soon as the transmission of the conditional handover command is initiated in the downlink, data forwarding may be initiated.

In step S913, the source cell may transmit a RRCReconfiguration message including a conditional reconfiguration to the UE. The conditional reconfiguration may be also referred to as (or, may comprise) conditional handover (CHO) configuration and/or a conditional handover command (e.g., CHO command). The conditional reconfiguration may comprise a list of conditional reconfigurations/conditional handover commands, including a conditional reconfiguration/conditional handover command for each of the candidate target cells (e.g., target cell 1, target cell 2). For example, the conditional reconfiguration may comprise a conditional reconfiguration/conditional handover command for the target cell 1, and a conditional reconfiguration/conditional handover command for the target cell 2. The conditional reconfiguration for a target cell may comprise an index/identifier identifying the corresponding conditional reconfiguration, a handover condition for the target cell, and/or a cell configuration (i.e., RRCReconfiguration message including the reconfigurationWithSync) for the target cell. The RRCReconfiguration message and/or reconfigurationWithSync for the target cell may comprise information required to access the target cell comprising at least one of a physical cell ID of the target cell, identifier of the UE (i.e., C-RNTI), HO validity timer (i.e., T304 timer), the target gNB security algorithm identifiers for the selected security algorithms, a set of dedicated RACH resources for contention-free random access (e.g., dedicated random access preamble), the association between RACH resources and SSB(s), the association between RACH resources and UE-specific CSI-RS configuration(s), common RACH resources, or system information of the target cell.

In step S915, the UE may perform an evaluation of the handover condition for the candidate target cells (e.g., target cell 1, target cell 2) and select a target cell for a handover among the candidate target cells. For example, the UE may perform measurements on the candidate target cells, and determine whether a candidate target cell fulfils a handover condition for the candidate target cell among the candidate target cells based on a result of the measurements on the candidate target cells. Or, the UE may determine whether the target cell/measurement result for the target cell fulfils the handover condition of the target cell. If the UE identifies that the target cell 1 fulfils a handover condition for the target cell 1, the UE may select the target cell 1 as a target cell for the handover.

In step S917, the UE may detach from the old cell i.e., the source cell and synchronize to a new cell i.e., the selected target cell. The UE may perform a handover from the source cell to the target cell based on applying the cell configuration. For example, upon receiving the handover command, the UE may start the T304 timer, and perform a contention-free random access towards the target cell based on the set of dedicated RACH resources.

In step S919, upon successful completion of the random access procedure, the UE may stop the T304 timer, and transmit a handover complete message (i.e., RRCReconfigurationComplete message) to the target cell. The UE may send the RRCReconfigurationComplete message comprising the C-RNTI to confirm the handover, to the target cell to indicate that the handover procedure is completed for the UE. The target RAN node may verify the C-RNTI sent in the RRCReconfigurationComplete message. The target RAN node can now begin sending data to the UE. When the random access fails and the T304 timer is still running, the UE may retry random access towards the target cell. Upon expiry of the T304 timer, the UE may declare handover failure (HOF) and perform an RRC re-establishment procedure.

In this disclosure, a method for efficient configuration switching between a serving cell and a candidate/target cell based on non-shared configuration part and shared-configuration part with selective configuration adjustment is proposed.

The UE may obtain multiple configuration parts configured for the UE. For example, the UE may receive the multiple configuration parts from a network. The configuration part may be used to configure the reference configuration and/or the modification configurations.

Each configuration part may be associated with one or more cells. Each configuration part may be associated with one or more cell IDs (cell indexes or physical cell IDs (PCIs)).

At least one of the following configuration parts may be configured:

- Non-shared common configuration part that is applicable only for the associated cell if the associated cell is a serving cell;

- Non-shared common configuration part that is applicable only for the associated cell if the associated cell is a non-serving cell;

- Non-shared dedicated configuration part that is applicable only for the associated cell if the associated cell is a serving cell;

- Non-shared dedicated configuration part that is applicable only for the associated cell if the associated cell is a non-serving cell;

- Shared-common configuration part that is applicable for multiple cells (applicable cells). Shared-common configuration part may have multiple shared-common configuration entries. For each of the applicable cells, one shared-common configuration entry may be associated and hence applied. For each of shared-common configuration entries, adjustment configuration may be also configured. Adjustment configuration may intend to adjust the corresponding shared- common configuration entry, depending on whether the applicable cell is a serving cell or non-serving cell. Adjustment configuration for serving cell and that for non-serving cell may be configured for the corresponding shared- common configuration entry.

- Shared-dedicated configuration part that is applicable for multiple cells (applicable cells). Applicable cell of the concerned shared-dedicated configuration part may be implicitly indicated or explicated indicated. Shared-dedicated configuration part may have multiple shared-dedicated configuration entries. For each of the applicable cells, one shared-dedicated configuration entry may be associated and hence applied. For each of shared-dedicated configuration entries, adjustment configuration may be also configured. Adjustment configuration may intend to adjust the corresponding shared-dedicated configuration entry, depending on whether the applicable cell is a serving cell or non-serving cell. Adjustment configuration for serving cell and that for non-serving cell may be configured for the corresponding shared-dedicated configuration entry.

The shared configuration part may be used to configure the reference configuration. The non-shared configuration part may be used to configure the modification configuration.

UE may determine applicable parts of configuration based on the configuration parts and which cell is a serving cell, possibly with configuration adjustment. The UE may determine the applicable parts upon mobility to a target cell.

For each non-shared common configuration part that is applicable if the associated cell is a serving cell:

- if the associated cell is a serving cell, UE may consider the configuration part as being active (i.e., the concerned configuration part is selected) or equivalently UE may activate the configuration part.

- if the associated cell is not a serving cell, UE may consider the configuration part as being inactive (i.e., the concerned configuration part is not selected) or equivalently UE may deactivate the configuration part.

For each non-shared dedicated configuration part that is applicable if the associated cell is a serving cell:

For each non-shared common configuration part that is applicable if the associated cell is a not serving cell:

- if the associated cell is a not serving cell, UE may consider the configuration part as being active (i.e., the concerned configuration part is selected) or equivalently UE may activate the configuration part.

- if the associated cell is a serving cell, UE may consider the configuration part as being inactive (i.e., the concerned configuration part is not selected) or equivalently UE may deactivate the configuration part.

For each non-shared dedicated configuration part that is applicable if the associated cell is not a serving cell:

- if the associated cell is not a serving cell, UE may consider the configuration part as being active (i.e., the concerned configuration part is selected) or equivalently UE may activate the configuration part.

For each shared-common configuration part, UE may select a shared-common configuration entry applicable for the serving cell and that for the other cell, based on the association relation between the shared-common configuration entries and applicable cells, possibly with configuration adjustment.

For each shared-dedicated configuration part, UE may select a shared-dedicated configuration entry applicable for the serving cell and that for other cell, based on the association relation between the shared-dedicated configuration entries and applicable cells, possibly with adjustment.

The UE may apply the determined applicable parts of configuration. The UE may apply the determined applicable parts upon mobility to a target cell.

UE may be configured with an explicit indicator indicating whether the concerned configuration part can remain inactive (or can enter deactivated) without being released when the associated PCI becomes a non-serving cell or whether the concerned configuration part should be released. UE may be configured with an explicit indicator indicating whether the concerned configuration part can remain active at least partly with a role change (via adaptation) when the associated PCI becomes a non-serving cell. The indicator can be configured when network configures the UE with the configuration parts or when providing mobility command.

Referring to FIG. 10, UE may be configured with configuration parameters for cell 1 and cell2. UE may be configured with non-shared serving cell configuration part for cell1 applicable only when the cell1 is a serving cell, and UE may also be configured with non-shared serving cell configuration part for cell2 applicable only when the cell2 is a serving cell, and shared-dedicated configuration part commonly applicable for cell1 and cell2 (i.e., applicable when cell1 is a serving cell and also when cell2 is a serving cell).

The shared-dedicated configuration part may include shared-dedicated configuration base1 applicable for cell1 and shared-dedicated configuration base2 applicable for the cell2. The shared-dedicated configuration part may include a shared-dedicated configuration base applicable for cell1 and the cell2. For the shared-dedicated configuration part, adjustment configuration part may also be configured. The adjustment configuration part may include adjustment configuration for cell1 and adjustment configuration for cell2.

The adjustment configuration for cell1 may include adjustment_1s that is used to adjust the shared-dedicated configuration base1 when the cell1 is a serving cell. The adjustment configuration for cell1 may include adjustment_1n that is used to adjust the shared-dedicated configuration base1 when the cell1 is a non-serving cell.

The adjustment configuration for cell2 may include adjustment_2s that is used to adjust the shared-dedicated configuration base2 when the cell2 is a serving cell. The adjustment configuration for cell2 may include adjustment_2n that is used to adjust the shared-dedicated configuration base2 when the cell2 is a non-serving cell.

For example, the reference configuration for cell#1 and cell#2 may comprise at least one of shared-dedicated configuration base1 or shared-dedicated configuration base2.

The modification configuration for cell#1 may comprise at least one of a modification configuration for serving cell related to cell#1 and a modification configuration for non-serving cell related to cell#1. The modification configuration for serving cell related to cell#1 may comprise at least one of common configuration part 1, non-shared dedicated configuration 1, or adjustment_1s. The modification configuration for non-serving cell related to cell#1 may comprise adjustment_1n.

The modification configuration for cell#2 may comprise at least one of a modification configuration for serving cell related to cell#2 and a modification configuration for non-serving cell related to cell#2. The modification configuration for serving cell related to cell#2 may comprise at least one of common configuration part 2, non-shared dedicated configuration 2, or adjustment_2s. The modification configuration for non-serving cell related to cell#2 may comprise adjustment_2n.

Referring to FIG. 11, cell#1 may be configured as a serving cell to the UE. Cell#2 may be configured as a non-serving cell, e.g., candidate cell to possibly become a serving cell.

UE may activate the non-shared serving cell configuration part for cell1. UE may deactivate the non-shared serving cell configuration part for cell2.

UE may activate the shared-dedicated configuration part with adjustments, where UE adjusts the shared-dedicated configuration base1 based on the adjustment_1s and also adjusts the shared-dedicated configuration base2 based on the adjustment_2n. Then UE may apply the activated configuration parts as a serving cell configuration.

Referring to FIG. 12, cell#2 may become a serving cell due to mobility or change of a serving cell.

UE may activate the non-shared serving cell configuration part for cell2. UE may deactivate the non-shared serving cell configuration part for cell1.

UE may activate the shared-dedicated configuration part with adjustments, where UE adjusts the shared-dedicated configuration base1 based on the adjustment_1n and also adjusts the shared-dedicated configuration base2 based on the adjustment_2s. Then UE may apply the activated configuration parts as a serving cell configuration.

Meanwhile, when a cell becomes a serving cell, the cell may be either a special cell (SpCell) or a SCell. So, to configure the serving cell, network may be sufficient to configure a special cell configuration (SpCellConfig) if the serving cell is a special cell or to configure a SCell configuration (SCellConfig) if the serving cell is a SCell.

In conditional mobility, a full RRC reconfiguration is preconfigured to UE as UE/cell group configuration for each candidate cell, where the UE applies the RRC reconfiguration if the candidate cell becomes a special cell. If there are multiple candidate cells to be configured and frequent mobility based on the pre-configuration among the candidate cells is required, the conditional mobility may incur excessive signalling overhead and large configuration latency.

To allow frequent mobility between configured candidate cells while reducing signalling overhead, it would be desirable to develop a new mobility method and configuration methods.

In the present disclosure, a common candidate configuration pool is introduced, and different cell group candidates refer to a subset of the contents of the common candidate configuration pool as per its need.

In the present disclosure, although the embodiments have been described as being applied to the case of MCG, this is illustrative and may also be applied to the case of SCG.

In particular, if a candidate cell becomes an SpCell or an SCell, depending on mobility scenarios, configuration structures and/or control parameters, the present disclosure proposes eliminating the ambiguity in how to provision the serving cell configuration related to the candidate cell.

FIG. 13 shows an example of a method performed by a UE according to an embodiment of the present disclosure. The method may also be performed by a wireless device.

Referring to FIG. 13, in step S1301, UE may receive, from a network, a cell configuration pool comprising a plurality of cell configurations for multiple candidate cells. Each of the plurality of cell configurations comprises at least one of: a special cell (SpCell) configuration applied based on a corresponding candidate cell being a special cell; or a secondary cell (SCell) configuration applied based on the corresponding candidate cell being a secondary cell.

In step S1303, the UE may determine to perform a mobility to a first target cell among the multiple candidate cells based on measuring reference signals related to the multiple target cells.

In step S1305, the UE may apply an SpCell configuration in a cell configuration for the first target cell.

In step S1307, the UE may apply an SCell configuration in a cell configuration for an SCell related to the first target cell.

According to various embodiments, the SCell related to the first target cell may belong to a cell group including the first target cell as an SpCell.

According to various embodiments, the UE may receive, from the network, a plurality of cell group configurations. The UE may identify a cell group configuration for the first target cell among the plurality of cell group configurations, wherein the cell group configuration comprises a first configuration identifier (ID) of the cell configuration for the first target cell, and a second configuration ID of the cell configuration for the SCell. The UE may identify the cell configuration for the first target cell informed by the first configuration ID in the cell group configuration. The UE may identify the cell configuration for the SCell informed by the second configuration ID in the cell group configuration.

According to various embodiments, the cell configuration for the first target cell may comprise a configuration ID matching the first configuration ID. The cell configuration for the SCell may comprise a configuration ID matching the second configuration ID.

According to various embodiments, the cell configuration for the first target cell may comprise the cell group configuration for the first target cell.

According to various embodiments, the UE may obtain measurement results for the multiple candidate cells based on measuring reference signals related to the multiple candidate cells. The UE may transmit, to the network, a measurement report comprising the measurement results for the multiple candidate cells. The UE may receive, from the network, information informing the first target cell as a mobility target.

According to various embodiments, the UE may obtain measurement results for the multiple candidate cells based on measuring reference signals related to the multiple candidate cells. The UE may evaluate a mobility condition for each of the multiple candidate cells based on the measurement results for the multiple candidate cells. The UE may determine the first target cell for which the mobility condition is satisfied among the multiple candidate cell.

According to various embodiments, the plurality of cell configurations may be maintained without being released after the mobility to the first target cell.

According to various embodiments, after performing the mobility to the first target cell, the UE may measure reference signals related to the multiple candidate cells excluding the first target cell. The UE may determine a second target cell among the multiple candidate cells excluding the first target cell based on measuring reference signals related to the multiple candidate cells excluding the first target cell. The UE may determine an SpCell configuration for the second target cell based on a cell group configuration for the second target cell. The UE may perform a mobility to the second target cell based on applying the SpCell configuration for the second target cell.

According to various embodiments, the cell group configuration for the second target cell may comprise the SpCell configuration.

According to various embodiments, the cell group configuration for the second target cell may comprise a configuration identifier (ID) of a cell configuration for the second target cell. The cell configuration for the second target cell may comprise the SpCell configuration.

According to various embodiments, the UE may apply an SCell configuration for a second SCell related to the second target cell. The SCell configuration for the second SCell may be included in the cell group configuration, or included in a cell configuration for the second SCell informed by a configuration ID in the cell group configuration.

According to various embodiments, the UE may receive an active cell group configuration. The UE may receive one or multiple candidate cell groups. Each candidate serving cell group may include a special cell candidate and zero or more SCell candidates. The UE may receive a candidate cell configuration pool for each of one or multiple candidate cells, where for each candidate cell, special cell configuration and SCell configuration are included. Upon mobility from the active cell group to a candidate cell group, the UE may select a candidate cell group including the candidate cell as special cell. The UE may apply the special cell configuration within the selected candidate cell group as a special cell configuration of the target cell group as active cell group configuration. The UE may apply the SCell cell configuration within the selected candidate cell group as a SCell cell configuration of the target cell group as active cell group configuration

FIG. 14 show an example of a signal flow between UE and network node according to an embodiment of the present disclosure. The network node may comprise a base station (BS).

Referring to FIG. 14, in step S1401, the network node may transmit, to a user equipment (UE), a cell configuration pool comprising a plurality of cell configurations for multiple candidate cells. Each of the plurality of cell configurations may comprise at least one of: a special cell (SpCell) configuration applied based on a corresponding candidate cell being a special cell; or a secondary cell (SCell) configuration applied based on the corresponding candidate cell being a secondary cell.

In step S1403, the network node may transmit, to the UE, reference signals related to the multiple candidate cells for a mobility to a target cell among the multiple candidate cells.

In step S1405, the UE may determine to perform a mobility to a target cell based on measuring the reference signals related to the multiple candidate cells.

In step S1407, the UE may apply an SpCell configuration in a cell configuration for the target cell.

In step S1409, the UE may apply an SCell configuration in a cell configuration for an SCell related to the target cell.

FIG. 15 shows an example of a method for determining serving cell configuration according to an embodiment of the present disclosure. The method may be performed by a UE and/or a wireless device.

Referring to FIG. 15, in step S1501, UE may an apply active cell group configuration for an active cell group including an SpCell and optionally one or more SCells. UE may be configured with the active cell group configuration, and apply the active cell group configuration. Serving cells may be configured within the active cell group configuration. For example, the active cell group configuration may comprise an SpCell configuration (i.e., SpCellConfig) for the SpCell, and optionally one or more SCell configurations (i.e., SCellConfig) for the one or more SCells.

In step S1503, UE may receive one or multiple cell group configurations for one or multiple candidate cell groups (i.e., CandidateCellGroupConfig). The exemplary information elements (IEs) included in the cell group configuration are shown in table 5:

CandidateCellGroupConfig-r18:=SEQUENCE {
//sPCell configuration control
spCellConfig_r18 CHOICE {
configID-r18 CellConfigID,
explicitSpCellConfig-r18 SpCellConfig
}

//Scell configuration control
sCellsToRemoveList-r18 CHOICE {
allSCellsToRemove NULL,
sCellsToRemove SEQUENCE (SIZE(1...maxNrofSCells)) OF ServingCellID
} OPTIONAL

sCellsToAddModList-r18 SEQUENCE(SIZE(1...maxNrofSCells)) OF CHOICE {
configID-r18 CellConfigID, //candidate cell configuration ID to add as SCell
explicitSCellConfig SCellConfig, //Explicit configuration to add or modify SCell
},

//candidate cell control
addServingCeellAsCandidateCell-r18 CHOICE {
ENUMERATED {true},
allowedSourceCellList SEQUENCE (SIZE (1...maxNrofSCells)) OF ServingCellID
}

allowedCandidateCellList-r18 CHOICE {
allCandCellsToAllow NULL,
candCellsToAllow SEQUENCE (SIZE(1...maxNrOfSCells)) OF CellConfigID
}
}

UE may be configured with the one or multiple candidate cell groups. Each candidate cell group may include a candidate SpCell and zero or more candidate SCells, and each cell group configuration for the corresponding candidate cell group may comprise a configuration of an SpCell (i.e., SpCellConfig), and configurations of zero or more SCells (i.e., sCellsToRemovelist/sCellsToAddModList).The configuration of an SpCell may comprise a configuration ID (i.e., configID), and/or an explicit SpCell configuration for the SpCell (i.e., explicitSpCellConfig). The configuration ID may refer to an SpCell configuration (i.e., candSpCellConfig) in a cell configuration (i.e., CandCellConfig) comprising the corresponding configuration ID (i.e., candidateCellConfigID) in the candidate cell configuration pool (i.e., CandidateCellPoolConfig).

For example, the explicit SpCell configuration may be configured/applied as full configuration. To make UE apply the full configuration for the SpCell, full configuration indicator for the SpCell may be included in the configuration of the SpCell. For another example, the explicit SpCell configuration may be configured/applied as delta configuration. To make UE apply the delta configuration for the SpCell, delta configuration indicator for the SpCell may be included in the configuration of the SpCell.

The configurations of zero or more SCells may comprise configurations to add/modify zero or more SCells (i.e., sCellsToAddModList), and/or configurations to remove zero or more SCells (i.e., sCellsToRemoveList).

The configurations to add/modify zero or more SCells may comprise a list of configurations of SCells to add/modify. Each configuration of an SCell may comprise a configuration ID (i.e., configID), and/or an explicit SCell configuration for the SCell (i.e., explicitSCellConfig). The configuration ID may refer to an SCell configuration (i.e., candSCellConfig) in a cell configuration (i.e., CandCellConfig) comprising the corresponding configuration ID (i.e., candidateCellConfigID) in the candidate cell configuration pool (i.e., CandidateCellPoolConfig).

For example, the explicit SCell configuration may be configured/applied as full configuration. To make UE apply the full configuration for the SCell, full configuration indicator for the SCell may be included in the configuration of the SCell. For another example, the explicit SCell configuration may be configured/applied as delta configuration. To make UE apply the delta configuration for the SCell, delta configuration indicator for the SCell may be included in the configuration of the SCell.

The configurations to remove zero or more SCells may comprise an indicator indicating whether to remove all SCells in the current active cell group (i.e., allSCellsToRemove), and/or a list of serving cell IDs related to SCells to remove.

Each cell group configuration for a candidate cell group may include control information controlling a candidate cell configuration pool upon mobility (i.e., addServingCellAsCandidateCell). For example, the control information may be a simple allow/disallow type indicator. This is to enable the control granularity per target cell. For another example, the control information may include a list of cells (i.e., a list of source cells/allowedSourceCellList). This is to enable the control granularity per source cell-target cell pair.

Each cell group configuration for a candidate cell group may comprise cell status information (i.e., allowedCandidateCellList) indicating which candidate cell within the candidate cell group/candidate cell configuration pool is active or inactive. For example, the cell status information may comprise "allCandCellsToAllow" field indicating that all candidate cells in the candidate cell group/candidate cell configuration pool are active, or comprise "candCellsToAllow" field indicating one or more cell configuration IDs that are active in the candidate cell group/candidate cell configuration pool.

In some implementations, the cell status information may not be included in a cell group configuration, but may be received from a network via a separate signalling.

In step S1505, UE may receive a candidate cell configuration pool (i.e., CandidateCellPoolConfig). The exemplary IEs included in the candidate cell configuration pool are shown in table 6:

CandidateCellPoolConfig:=SEQUENCE(SIZE(1...maxCandidateCell)) OF CandCellConfig

CandCellConfig ::=SEQUENCE {
candidateCellConfigID-r18 CellConfigID,
candSpCellconfig-r18 SpCellConfig-r18 OPTIONAL
candSCellConfig-r18 SCellConfig-r18 OPTIONAL
status CHOICE {
active NULL,
inactive NULL
}
}

UE may be configured with the candidate cell configuration pool. The candidate cell configuration pool may include a set of cell configurations for a set of candidate cells, where each cell configuration is related to a corresponding candidate cell in the set of candidate cells.Each cell configuration for a candidate cell (i.e., CandCellConfig) in the candidate cell configuration pool may include a configuration ID (i.e., candidateCellConfigID), SpCell configuration (i.e., candSpCellconfig), SCell configuration (i.e., candSCellConfig) and/or status information. The SpCell configuration may be applied when the candidate cell is configured as an SpCell, and may comprise a cell ID of the SpCell and the corresponding configuration (e.g., sPCellConfig). The SCell configuration may be applied when the candidate cell is configured an SCell, and may comprise a cell ID of the SCell and the corresponding configuration (e.g., SCellconfig). The status information may be determined/informed by the cell status information included in a cell group configuration or received from a network.

In some implementations, a cell configuration for a candidate cell and/or an SpCell configuration in the cell configuration may comprise a cell group configuration for the candidate cell (i.e., cell group configuration for a candidate cell group including the candidate cell as an SpCell).

In step S1507, upon mobility to a candidate cell or upon initiation of mobility to the candidate cell, UE may select a cell group configuration for the candidate cell (i.e., cell group configuration for a candidate cell group including the candidate cell as SpCell) as an active cell group configuration.

In case of handover/mobility to a candidate cell, UE may select a cell group configuration for a candidate cell group including the candidate cell as an SpCell, and consider the selected cell group configuration and the candidate cell group as an active cell group configuration and an active cell group, respectively. Other cell group configurations may not be considered as an active cell group configuration.

In step S1509, UE may determine/apply a configuration of each serving cell in the active cell group based on at least one of the active cell group configuration or a cell configuration for each serving cell.

For each serving cell of the active cell group configuration, UE may determine the configuration of each serving cell.

For an SpCell of the active cell group, if an SpCell configuration for the SpCell is derived from the candidate cell configuration pool, UE may apply the SpCell configuration within a cell configuration for the SpCell as a configuration of the SpCell in the active cell group. If an SpCell configuration for the SpCell is based on full/delta configuration, UE may apply the full/delta configuration for the SpCell (i.e., explicitSpCellConfig) configured by the active cell group configuration.

For an SCell of the active cell group, if an SCell configuration for the SCell is derived from the candidate cell configuration pool, UE may apply the SCell configuration within a cell configuration for the SCell as a configuration of the SCell in the active cell group. If an SCell configuration for the SCell is based on full/delta configuration, UE may apply the full/delta configuration for the SCell (i.e., explicitSCellConfig) configured by the active cell group configuration.

For example, UE may be configured with MCG including PCell and SCells as shown in table 7:

PCell=SpCellConfig[x]
SCell1=SCellConfig[a]=
{SERVING_CELL_ID_2,...}
SCell2=SCellConfig[b]=
{SERVING_CELL_ID_3,...}
SCell3=SCellConfig[c]=
{SERVING_CELL_ID_4,...}

Also, UE may be configured with three candidate cell groups as shown in table 8:

candidateCellGroupConfig[1] = {

sPCellConfig-r18=configID=1, //sPCell is configured with candiSpCellConfig[1] in the candidateCellPoolConfig

sCellsToRemoveList-r18 = null,
sCellsToAddModList-r18 = {
configID=2, //SCell is configured with candiSCellConfig[2] in the candidateCellPoolConfig
configID=3 //SCell is configured with candiSCellConfig[3] in the candidateCellPoolConfig
},
addServingCellAsCandidateCell-r18 = true
allowedCandidateCellList-r18 = candCellsToAllow = {2}
}

candidateCellGroupConfig[2] = {

sPCellConfig_r18=explicitSpCellconfig, //sPCell is configured with SpCellConfig within candidateCellPoolConfig[2]

sCellsToRemoveList-r18 = sCellsToRemove {
SERVING_CELL_ID_2, //SCell1
SERVING_CELL_ID_3, //SCell2
},
sCellsToAddModList-r18 = {
explicitSCellConfig[1] = {SERVING_CELL_ID_4,...} //SCell3 is reconfigured with SCellConfig IE within candidateCellGroupConfig[2] as delta signaling
explicitSCellConfig[2] = {SERVING_CELL_ID_6,...} //A New SCell with SERVING_CELL_ID_6 is added with SCellConfig IE within candidateCellGroupConfig[2]
},
addServingCellAsCandidateCell-r18 = true
allowedCandidateCellList-r18 = allCandCellsToAllow
}

candidateCellGroupConfig[3] = {

sPCellConfig-r18=configID=3, //sPCell is configured with candiSpCellConfig[3] in the candidateCellPoolConfig

sCellsToRemoveList-r18 = null,
sCellsToAddModList-r18 = {
configID=1,
explicitSCellConfig = {SERVING_CELL_ID_6,...} //A New SCell with SERVING_CELL_ID_6 is added with SCellConfig IE within candidateCellGroupConfig[3]
},
addServingCellAsCandidateCell-r18 = false
allowedCandidateCellList-r18 = allCandCellsToAllow
}

Further, UE may be configured with a candidate cell configuration pool as shown in table 9:

Alt_a) // Only non-serving cell is configured as candidate cell
candidateCellPoolConfig = {
candCellConfig[1] = {1, candSpCellconfig[1], candSCellConfig[1], active}
candCellConfig[2] = {2, candSpCellconfig[2], candSCellConfig[2], active}
candCellConfig[3] = {3, candSpCellconfig[3], candSCellConfig[3], active}

Alt_b) // current serving cell can be configured as candidate cell
candidateCellPoolConfig = {
candCellConfig[1] = {1, candSpCellconfig[1], candSCellConfig[1], active}
candCellConfig[2] = {2, candSpCellconfig[2], candSCellConfig[2], active}
candCellConfig[3] = {3, candSpCellconfig[3], candSCellConfig[3], active}
candCellConfig[4] = {4, candSpCellconfig[4], candSCellConfig[4], inactive}

Then, upon mobility, the UE may apply the following CG configurations as active CG configuration, according to the present disclosure:Case 1) Upon (initiation of) mobility to a candidate cell corresponding to candCellConfig[1], UE may select the candidateCellGroupConfig[1] as active CG configuration and apply the configurations of the serving cells for the special and SCells for the CG based on the candidateCellGroupConfig[1] as shown in table 10:

CG configuration when a cell corresponding to candSpCellConfig[1] is a sPCell
sPCellConfig = candSpCellconfig[1],

SCellConfig = SCellConfig[a],
SCellConfig = SCellConfig[b],
SCellConfig = SCellConfig[c],

SCellConfig = candSCellConfig[2],
SCellConfig = candSCellConfig[3],

}

That is, according to candidateCellGroupConfig[1], since sPCellConfig comprises configID set to 1, UE should apply candSpCellconfig[1] within candCellConfig[1] comprising candidateCellConfigID set to 1. Further, according to candidateCellGroupConfig[1], since sCellsToAddModList comprises configID set to 2 and configID set to 3, UE should add/apply candSCellconfig[2] within candCellConfig[2] comprising candidateCellConfigID set to 2 and add/apply candSCellconfig[3] within candCellConfig[3] comprising candidateCellConfigID set to 3.Case 2) Upon (initiation of) mobility to a candidate cell corresponding to candCellConfig[2], UE may select the candidateCellGroupConfig[2] as active CG configuration and apply the configurations of the serving cells for the SpCell and SCells for the CG based on the candidateCellGroupConfig[2] as shown in table 11:

CG configuration when a cell corresponding to candSpCellConfig[2] is a sPCell
sPCellConfig = candSpCellconfig[2],

SCellConfig = Delta(SCellConfig[c], explicitSCellConfig[1] within candidateCellGroupConfig[2]) // Delta(A, B) is a delta configuration taking A as base configuration and B applies on top of the base configuration as specified in 38.331
SCellConfig = explicitSCellConfig[2] within candidateCellGroupConfig[2])

SCellConfig = candSCellConfig[1],
SCellConfig = candSCellConfig[3],

}

That is, according to candidateCellGroupConfig[2], since sPCellConfig comprises explicitSpCellConfig, UE should apply SpCellconfig indicated by the explicitSpCellConfig in the candidateCellGroupConfig[2]. Further, according to candidateCellGroupConfig[2], since sCellsToRemoveList comprises sCellsToRemove informing SERVING_CELL_ID_2 and SERVING_CELL_ID_3, UE may remove SCellConfig[a] and SCellConfig[b] related to SERVING_CELL_ID_2 and SERVING_CELL_ID_3, respectively. The sCellsToAddModList comprises explicitSCellConfig[1] for SERVING_CELL_ID_4 which is related to already configured SCellConfig[c], and explicitSCellConfig[2] for SERVING_CELL_ID_6 which is newly configured. Therefore, UE may apply explicitSCellConfig[1] as delta configuration to SCellConfig[c] (i.e., modification), and add/apply SCellConfig indicated by the explicitSCellConfig[2] in the candidateCellGroupConfig[2].

Case 3) Upon (initiation of) mobility to a candidate cell corresponding to candCellConfig[3], UE may select the candidateCellGroupConfig[3] as active CG configuration and apply the configurations of the serving cells for the SpCell and SCells for the CG based on the candidateCellGroupConfig[3] as shown in table 12:

CG configuration when a cell corresponding to candSpCellConfig[3] is a sPCell
sPCellConfig = candSpCellconfig[3],

SCellConfig = SCellConfig[a],
SCellConfig = SCellConfig[b],
SCellConfig = SCellConfig[c],

SCellConfig = candSCellConfig[2],
SCellConfig = explicitSCellConfig within candidateCellGroupConfig[3])

}

That is, according to candidateCellGroupConfig[3], since sPCellConfig comprises configID set to 3, UE should apply candSpCellconfig[3] within candCellConfig[3] comprising candidateCellConfigID set to 3. Further, according to candidateCellGroupConfig[3], since sCellsToAddModList comprises configID set to 1 and explicitSCellConfig for SERVING_CELL_ID_6 which is newly configured, UE should add/apply candSCellconfig[1] within candCellConfig[1] comprising candidateCellConfigID set to 1 and add/apply SCellConfig indicated by the explicitSCellConfig within the candidateCellGroupConfig[3].Furthermore, the method in perspective of the UE described in the present disclosure (e.g., in FIG. 13) may be performed by the first wireless device 100 shown in FIG. 2 and/or the UE 100 shown in FIG. 3.

More specifically, the UE comprises at least one transceiver, at least processor, and at least one computer memory operably connectable to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations.

The operations comprise: receiving, from a network, a cell configuration pool comprising a plurality of cell configurations for multiple candidate cells, wherein each of the plurality of cell configurations comprises at least one of: a special cell (SpCell) configuration applied based on a corresponding candidate cell being a special cell; or a secondary cell (SCell) configuration applied based on the corresponding candidate cell being a secondary cell; and based on performing a mobility to a first target cell: applying an SpCell configuration in a cell configuration for the first target cell; and applying an SCell configuration in a cell configuration for an SCell related to the first target cell.

Furthermore, the method in perspective of the UE described in the present disclosure (e.g., in FIG. 13) may be performed by a software code 105 stored in the memory 104 included in the first wireless device 100 shown in FIG. 2.

More specifically, at least one computer readable medium (CRM) stores instructions that, based on being executed by at least one processor, perform operations comprising: receiving, from a network, a cell configuration pool comprising a plurality of cell configurations for multiple candidate cells, wherein each of the plurality of cell configurations comprises at least one of: a special cell (SpCell) configuration applied based on a corresponding candidate cell being a special cell; or a secondary cell (SCell) configuration applied based on the corresponding candidate cell being a secondary cell; and based on performing a mobility to a first target cell: applying an SpCell configuration in a cell configuration for the first target cell; and applying an SCell configuration in a cell configuration for an SCell related to the first target cell.

Furthermore, the method in perspective of the UE described in the present disclosure (e.g., in FIG. 13) may be performed by control of the processor 102 included in the first wireless device 100 shown in FIG. 2 and/or by control of the processor 102 included in the UE 100 shown in FIG. 3.

More specifically, an apparatus configured to/adapted to operate in a wireless communication system (e.g., wireless device/UE) comprises at least processor, and at least one computer memory operably connectable to the at least one processor. The at least one processor is configured to/adapted to perform operations comprising: receiving, from a network, a cell configuration pool comprising a plurality of cell configurations for multiple candidate cells, wherein each of the plurality of cell configurations comprises at least one of: a special cell (SpCell) configuration applied based on a corresponding candidate cell being a special cell; or a secondary cell (SCell) configuration applied based on the corresponding candidate cell being a secondary cell; and based on performing a mobility to a first target cell: applying an SpCell configuration in a cell configuration for the first target cell; and applying an SCell configuration in a cell configuration for an SCell related to the first target cell.

Furthermore, the method in perspective of a network node described in the present disclosure (e.g., in FIG. 14) may be performed by the second wireless device 200 shown in FIG. 2.

More specifically, the network node comprises at least one transceiver, at least processor, and at least one computer memory operably connectable to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations.

The operations comprise: transmitting, to a user equipment (UE), a cell configuration pool comprising a plurality of cell configurations for multiple candidate cells, wherein each of the plurality of cell configurations comprises at least one of: a special cell (SpCell) configuration applied based on a corresponding candidate cell being a special cell; or a secondary cell (SCell) configuration applied based on the corresponding candidate cell being a secondary cell; and transmitting, to the UE, reference signals related to the multiple candidate cells for a mobility to a target cell among the multiple candidate cells, wherein the UE is configured to, based on performing a mobility to a first target cell: apply an SpCell configuration in a cell configuration for the target cell; and apply an SCell configuration in a cell configuration for an SCell related to the target cell.

The present disclosure may have various advantageous effects.

Claims in the present disclosure can be combined in a various way. For instance, technical features in method claims of the present disclosure can be combined to be implemented or performed in an apparatus, and technical features in apparatus claims can be combined to be implemented or performed in a method. Further, technical features in method claim(s) and apparatus claim(s) can be combined to be implemented or performed in an apparatus. Further, technical features in method claim(s) and apparatus claim(s) can be combined to be implemented or performed in a method. Other implementations are within the scope of the following claims.

Claims

A method performed by a user equipment (UE) in a wireless communication system, the method comprising:

receiving, from a network, a cell configuration pool comprising a plurality of cell configurations for multiple candidate cells,

wherein each of the plurality of cell configurations comprises at least one of:

a special cell (SpCell) configuration applied based on a corresponding candidate cell being a special cell; or

a secondary cell (SCell) configuration applied based on the corresponding candidate cell being a secondary cell; and

based on performing a mobility to a first target cell:

applying an SpCell configuration in a cell configuration for the first target cell; and

applying an SCell configuration in a cell configuration for an SCell related to the first target cell.
The method of claim 1, wherein the SCell related to the first target cell belongs to a cell group including the first target cell as an SpCell.
The method of claim 1, further comprising:

receiving, from the network, a plurality of cell group configurations;

identifying a cell group configuration for the first target cell among the plurality of cell group configurations, wherein the cell group configuration comprises a first configuration identifier (ID) of the cell configuration for the first target cell, and a second configuration ID of the cell configuration for the SCell;

identifying the cell configuration for the first target cell informed by the first configuration ID in the cell group configuration; and

identifying the cell configuration for the SCell informed by the second configuration ID in the cell group configuration.
The method of claim 3, wherein the cell configuration for the first target cell comprises a configuration ID matching the first configuration ID, and

wherein the cell configuration for the SCell comprises a configuration ID matching the second configuration ID.
The method of claim 3, wherein the cell configuration for the first target cell comprises the cell group configuration for the first target cell.
The method of claim 1, wherein the performing of the mobility to the first target cell comprises:

obtaining measurement results for the multiple candidate cells based on measuring reference signals related to the multiple candidate cells;

transmitting, to the network, a measurement report comprising the measurement results for the multiple candidate cells; and

receiving, from the network, information informing the first target cell as a mobility target.
The method of claim 1, wherein the performing of the mobility to the first target cell comprises:

obtaining measurement results for the multiple candidate cells based on measuring reference signals related to the multiple candidate cells;

evaluating a mobility condition for each of the multiple candidate cells based on the measurement results for the multiple candidate cells; and

determining the first target cell for which the mobility condition is satisfied among the multiple candidate cell.
The method of claim 1, wherein the plurality of cell configurations are maintained without being released after the mobility to the first target cell.
The method of claim 1, further comprising:

after performing the mobility to the first target cell, measuring reference signals related to the multiple candidate cells excluding the first target cell;

determining a second target cell among the multiple candidate cells excluding the first target cell based on measuring reference signals related to the multiple candidate cells excluding the first target cell;

determining an SpCell configuration for the second target cell based on a cell group configuration for the second target cell; and

performing a mobility to the second target cell based on applying the SpCell configuration for the second target cell.
The method of claim 9, wherein the cell group configuration for the second target cell comprises the SpCell configuration.
The method of claim 9, wherein the cell group configuration for the second target cell comprises a configuration identifier (ID) of a cell configuration for the second target cell, and

wherein the cell configuration for the second target cell comprises the SpCell configuration.
The method of claim 9, further comprising:

applying an SCell configuration for a second SCell related to the second target cell,

wherein the SCell configuration for the second SCell is included in the cell group configuration, or included in a cell configuration for the second SCell informed by a configuration ID in the cell group configuration.
The method of claims 1 to 12, wherein the UE is in communication with at least one of a mobile device, a network, or autonomous vehicles.
A user equipment (UE) configured to operate in a wireless communication system, the UE comprising:

at least one transceiver;

at least one processor; and

at least one memory operatively coupled to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations comprising:

receiving, from a network, a cell configuration pool comprising a plurality of cell configurations for multiple candidate cells,

wherein each of the plurality of cell configurations comprises at least one of:

a special cell (SpCell) configuration applied based on a corresponding candidate cell being a special cell; or

a secondary cell (SCell) configuration applied based on the corresponding candidate cell being a secondary cell; and

based on performing a mobility to a first target cell:

applying an SpCell configuration in a cell configuration for the first target cell; and

applying an SCell configuration in a cell configuration for an SCell related to the first target cell.
The UE of claim 14, wherein the UE is arranged to implement a method of one of claims 2 to 13.
A network node configured to operate in a wireless communication system, the network node comprising:

at least one transceiver;

at least one processor; and

at least one memory operatively coupled to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations comprising:

transmitting, to a user equipment (UE), a cell configuration pool comprising a plurality of cell configurations for multiple candidate cells,

wherein each of the plurality of cell configurations comprises at least one of:

a special cell (SpCell) configuration applied based on a corresponding candidate cell being a special cell; or

a secondary cell (SCell) configuration applied based on the corresponding candidate cell being a secondary cell; and

transmitting, to the UE, reference signals related to the multiple candidate cells for a mobility to a target cell among the multiple candidate cells,

wherein the UE is configured to, based on performing a mobility to a first target cell:

apply an SpCell configuration in a cell configuration for the target cell; and

apply an SCell configuration in a cell configuration for an SCell related to the target cell.
A method performed by a network node configured to operate in a wireless communication system, the method comprising:

transmitting, to a user equipment (UE), a cell configuration pool comprising a plurality of cell configurations for multiple candidate cells,

wherein each of the plurality of cell configurations comprises at least one of:

a special cell (SpCell) configuration applied based on a corresponding candidate cell being a special cell; or

a secondary cell (SCell) configuration applied based on the corresponding candidate cell being a secondary cell; and

transmitting, to the UE, reference signals related to the multiple candidate cells for a mobility to a target cell among the multiple candidate cells,

wherein the UE is configured to, based on performing a mobility to a target cell:

apply an SpCell configuration in a cell configuration for the first target cell; and

apply an SCell configuration in a cell configuration for an SCell related to the target cell.
The method of claim 17, wherein the UE is arranged to implement a method of one of claims 1 to 13.
An apparatus adapted to operate in a wireless communication system, the apparatus comprising:

at least processor; and

at least one memory operatively coupled to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations comprising:

receiving, from a network, a cell configuration pool comprising a plurality of cell configurations for multiple candidate cells,

wherein each of the plurality of cell configurations comprises at least one of:

a special cell (SpCell) configuration applied based on a corresponding candidate cell being a special cell; or

a secondary cell (SCell) configuration applied based on the corresponding candidate cell being a secondary cell; and

based on performing a mobility to a first target cell:

applying an SpCell configuration in a cell configuration for the first target cell; and

applying an SCell configuration in a cell configuration for an SCell related to the first target cell.
A non-transitory computer readable medium (CRM) having stored thereon a program code implementing instructions that, based on being executed by at least one processor, perform operations comprising:

receiving, from a network, a cell configuration pool comprising a plurality of cell configurations for multiple candidate cells,

wherein each of the plurality of cell configurations comprises at least one of:

a special cell (SpCell) configuration applied based on a corresponding candidate cell being a special cell; or

a secondary cell (SCell) configuration applied based on the corresponding candidate cell being a secondary cell; and

based on performing a mobility to a first target cell:

applying an SpCell configuration in a cell configuration for the first target cell; and

applying an SCell configuration in a cell configuration for an SCell related to the first target cell.