WO2023139399A1

WO2023139399A1 - Cell role changing between primary cell and secondary cell

Info

Publication number: WO2023139399A1
Application number: PCT/IB2022/000038
Authority: WO
Inventors: Hao Lin
Original assignee: Orope France Sarl
Priority date: 2022-01-24
Filing date: 2022-01-24
Publication date: 2023-07-27

Abstract

A method by a user equipment (UE) includes being configured by a base station, with a first serving cell and a second serving cell and receiving from the base station, a first information, wherein the first information is relevant to a role change between the first serving cell and the second serving cell. The first serving cell is a primary cell (PCell), and the second serving cell is a first secondary cell (SCell) or a first primary secondary cell group (SCG) cell (PSCell).

Description

CELL ROLE CHANGING BETWEEN PRIMARY CELL AND SECONDARY CELL

BACKGROUND OF DISCLOSURE

1. Field of the Disclosure

[0001] The present disclosure relates to the field of communication systems, and more particularly, to an apparatus and a method of wireless communication, which can provide a good communication performance and/or high reliability.

2. Description of the Related Art

[0002] Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple- access systems include fourth generation (4G) systems such as long term evolution (LTE) systems, LTE-advanced (LTE-A) systems, or LTE-A pro systems, and fifth generation (5G) systems which may be referred to as new radio (NR) systems. These systems may employ technologies such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT- S-OFDM). A wireless multiple-access communications system may include a number of base stations or network access nodes, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE).

[0003] In a 3rd generation partnership project (3GPP) system, a UE is accessing to a network in a primary cell (PCell). The PCell controls a UE connection status, e.g., if the PCell has a connection loss, the UE will lose the connection status and a secondary cell (SCell) connection will be automatically cancelled. In some cases, if the network wants to shut down a serving cell for the reason of power saving, the network might have difficulty in shutting down the PCell for the UE.

SUMMARY

[0004] An object of the present disclosure is to propose an apparatus (such as a user equipment (UE) and/or a base station) and a method of wireless communication, which can provide a network power saving, allow a network to shut down a first serving cell such as a primary cell (PCell) while still maintain a connection for a UE, provide a good communication performance, and/or provide high reliability.

[0005] In a first aspect of the present disclosure, a method of wireless communication by a user equipment (UE) comprises being configured by a base station, with a first serving cell and a second serving cell and receiving from the base station, a first information, wherein the first information is relevant to a role change between the first serving cell and the second serving cell. [0006] In some embodiments of the above method according to the first aspect of the present disclosure, the UE is configured to receive the first information from the first serving cell or the second serving cell. [0007] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, the first serving cell is a primary cell (PCell), and the second serving cell is a first secondary cell (SCell) or a first primary secondary cell group (SCG) cell (PSCell).

[0008] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, the UE is further configured by the base station, with a third serving cell, and the UE is configured to receive the first information from the first serving cell, the second serving cell, or the third serving cell.

[0009] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, the first serving cell is a PCell, the second serving cell is a first SCell or a first PSCell, and the third serving cell is a second SCell.

[0010] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, the role change between the first serving cell and the second serving cell comprises that the second seving cell is to be the PCell and/or a current PCell is to be a SCell.

[0011] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, the first information comprises a synchronization signal block (SSB) related information, a system information block typel (SIB1) relevant information, a common search space (CSS) set configuration, and/or a PCell role change command.

[0012] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, the SSB related information comprises a frequency location and/or one or more SSB indexes.

[0013] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, the SSB frequency location comprises a global synchronization channel number (GSCN) value. [0014] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, one or more SSBs of the SSB related information are transmitted in the second serving cell.

[0015] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, an SIB1 of the SIB1 relevant information is transmitted in the second serving cell as a PCell.

[0016] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, a CSS of the CSS set configuration comprises at least one of the followings: a typeO CSS, a type 0A CSS, a typel CSS, a type 2 CSS, or type 3 CSS.

[0017] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, the CSS set configuration configures one or more CSS monitoring occasions in the second serving cell for the UE.

[0018] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, the method further comprises starting to monitor one or more physical downlink control channels (PDCCHs) in configured one or more CSS sets after the role change between the first serving cell and the second serving cell is performed.

[0019] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, the PCell role change command provides information about a cell identifier (ID) of the second serving cell, where the cell ID is physical cell ID or a SCell index.

[0020] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, the method further comprises transmitting a second information to the base station after receiving the first information from the base station.

[0021] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, the second information is transmitted to the first serving cell or the second serving cell.

[0022] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, the second information is used to inform the base station to start the role change between the first serving cell and the second serving cell.

[0023] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, the second information comprises a physical random access channel (PRACH) transmission performed by the UE.

[0024] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, the PRACH transmission is contention based or contention free.

[0025] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, when the PRACH transmission is contention based, the UE selects one or more PRACH resources among a set of PRACH resources.

[0026] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, the set of PRACH resources is pre-configured by the base station.

[0027] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, a PRACH resource configuration of the PRACH transmission is transmitted in a system information, in the first information, or in a UE dedicated radio resource control (RRC) signaling.

[0028] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, when the PRACH transmission is contention free, a PRACH preamble or a time-frequency resource is configured by the base station for the UE to transmit the PRACH transmission.

[0029] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, the second information is conveyed in a physical uplink shared channel (PUSCH) in one or more symbols in time domain and/or in one or more resource blocks in frequency domain.

[0030] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, PUSCH resources are selected by the UE in a set of PUSCH resources pre-configured by the base station. [0031] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, PUSCH resources are scheduled by a first downlink control information (DO).

[0032] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, the first DCI is detected by the UE and is transmitted from the second serving cell.

[0033] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, the method further comprises monitoring a response carrying a third information from the second serving cell after transmitting the second information.

[0034] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, when the response is received by the UE, the UE assumes that the role change between the first serving cell and the second serving cell is performed.

[0035] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, the third information is carried in a physical downlink shared channel (PDSCH) scheduled by a second DCI from the first SCell.

[0036] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, the DCI is cyclic redundancy check (CRC) scrambled with a radio network temporary identifier (RNTI).

[0037] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, an RNTI value is relevant to the PRACH resource, or the RNTI value is pre-defined, preconfigured, or a cell-RNTI (C-RNTI).

[0038] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, after the UE receives the third information, the UE considers that the role change between the first serving cell and the second serving cell is performed.

[0039] In some embodiments of any one of the above methods according to the first aspect of the present disclosure, when the UE determines that the role change between the first serving cell and the second serving cell is performed, the UE treats the first SCell as the PCell.

[0040] In a second aspect of the present disclosure, a method of wireless communication by a base station comprises configuring, to a user equipment (UE), a first serving cell and a second serving cell and transmitting, to the UE, a first information, wherein the first information is relevant to a role change between the first serving cell and the second serving cell.

[0041] In some embodiments of the above method according to the second aspect of the present disclosure, the first serving cell or the second serving cell is configured to transmit the first information from to the UE.

[0042] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, the first serving cell is a primary cell (PCell), and the second serving cell is a first secondary cell (SCell) or a first primary secondary cell group (SCG) cell (PSCell). [0043] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, the base station further configures, to the UE a third serving cell, and the first serving cell, the second serving cell, or the third serving cell is configured to transmit, to the UE, the first information from.

[0044] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, the first serving cell is a PCell, the second serving cell is a first SCell or a first PSCell, and the third serving cell is a second SCell.

[0045] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, the role change between the first serving cell and the second serving cell comprises that the second seving cell is to be the PCell and/or a current PCell is to be a SCell.

[0046] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, the first information comprises a synchronization signal block (SSB) related information, a system information block typel (SIB1) relevant information, a common search space (CSS) set configuration, and/or a PCell role change command.

[0047] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, the SSB related information comprises a frequency location and/or one or more SSB indexes.

[0048] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, the SSB frequency location comprises a global synchronization channel number (GSCN) value.

[0049] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, one or more SSBs of the SSB related information are transmitted in the second serving cell.

[0050] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, an SIB1 of the SIB1 relevant information is transmitted in the second serving cell as a PCell.

[0051] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, a CSS of the CSS set configuration comprises at least one of the followings: a typeO CSS, a type 0A CSS, a typel CSS, a type 2 CSS, or type 3 CSS.

[0052] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, the CSS set configuration configures one or more CSS monitoring occasions in the second serving cell for the UE.

[0053] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, the method further comprises controlling the UE to start to monitor one or more physical downlink control channels (PDCCHs) in configured one or more CSS sets after the role change between the first serving cell and the second serving cell is performed. [0054] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, the PCell role change command provides information about a cell identifier (ID) of the second serving cell, where the cell ID is physical cell ID or a SCell index.

[0055] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, the method further comprises receiving a second information from the UE after transmitting the first information to the UE.

[0056] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, the second information is transmitted to the first serving cell or the second serving cell. [0057] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, the second information is used to inform the base station to start the role change between the first serving cell and the second serving cell.

[0058] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, the second information comprises a physical random access channel (PRACH) transmission performed by the UE.

[0059] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, the PRACH transmission is contention based or contention free.

[0060] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, when the PRACH transmission is contention based, the base station controls the UE to select one or more PRACH resources among a set of PRACH resources.

[0061] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, the set of PRACH resources is pre-configured by the base station.

[0062] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, a PRACH resource configuration of the PRACH transmission is transmitted in a system information, in the first information, or in a UE dedicated radio resource control (RRC) signaling.

[0063] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, when the PRACH transmission is contention free, a PRACH preamble or a timefrequency resource is configured by the base station for the UE to transmit the PRACH transmission.

[0064] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, the second information is conveyed in a physical uplink shared channel (PUSCH) in one or more symbols in time domain and/or in one or more resource blocks in frequency domain.

[0065] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, PUSCH resources are selected by the UE in a set of PUSCH resources pre-configured by the base station.

[0066] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, PUSCH resources are scheduled by a first downlink control information (DO). [0067] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, the first DO is detected by the UE and is transmitted from the second serving cell.

[0068] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, the method further comprises controlling the UE to monitor a response carrying a third information from the second serving cell after transmitting the second information.

[0069] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, when the response is received by the UE, the base station controls the UE to assume that the role change between the first serving cell and the second serving cell is performed.

[0070] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, the third information is carried in a physical downlink shared channel (PDSCH) scheduled by a second DCI from the first SCell.

[0071] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, the DCI is cyclic redundancy check (CRC) scrambled with a radio network temporary identifier (RNTI).

[0072] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, an RNTI value is relevant to the PRACH resource, or the RNTI value is pre-defined, pre-configured, or a cell-RNTI (C-RNTI).

[0073] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, after the third information is received by the UE, the base station controls the UE to consider that the role change between the first serving cell and the second serving cell is performed.

[0074] In some embodiments of any one of the above methods according to the second aspect of the present disclosure, when the base station controls the UE to determine that the role change between the first serving cell and the second serving cell is performed, the base station controls the UE to treat the first SCell as the PCell.

[0075] In a third aspect of the present disclosure, a user equipment comprises a memory, a transceiver, and a processor coupled to the memory and the transceiver. The processor is configured to perform the above method.

[0076] In a fourth aspect of the present disclosure, a base station comprises a memory, a transceiver, and a processor coupled to the memory and the transceiver. The processor is configured to perform the above method.

[0077] In a fifth aspect of the present disclosure, a non-transitory machine-readable storage medium has stored thereon instructions that, when executed by a computer, cause the computer to perform the above method.

[0078] In a sixth aspect of the present disclosure, a chip includes a processor, configured to call and run a computer program stored in a memory, to cause a device in which the chip is installed to execute the above method. [0079] In a seventh aspect of the present disclosure, a computer readable storage medium, in which a computer program is stored, causes a computer to execute the above method.

[0080] In an eighth aspect of the present disclosure, a computer program product includes a computer program, and the computer program causes a computer to execute the above method.

[0081] In a ninth aspect of the present disclosure, a computer program causes a computer to execute the above method.

BRIEF DESCRIPTION OF DRAWINGS

[0082] In order to illustrate the embodiments of the present disclosure or related art more clearly, the following figures will be described in the embodiments are briefly introduced. It is obvious that the drawings are merely some embodiments of the present disclosure, a person having ordinary skill in this field can obtain other figures according to these figures without paying the premise.

[0083] FIG. 1 is a block diagram of one or more user equipments (UEs) and a base station (e.g., gNB or eNB) of communication in a communication network system (e.g., non-terrestrial network (NTN) or a terrestrial network) according to an embodiment of the present disclosure.

[0084] FIG. 2 is a flowchart illustrating a method of wireless communication performed by a user equipment (UE) according to an embodiment of the present disclosure.

[0085] FIG. 3 is a flowchart illustrating a method of wireless communication performed by a base station according to an embodiment of the present disclosure.

[0086] FIG. 4 is a schematic diagram illustrating a serving cell role change procedure according to an embodiment of the present disclosure.

[0087] FIG. 5 is a schematic diagram illustrating a serving cell role change procedure according to an embodiment of the present disclosure.

[0088] FIG. 6 is a schematic diagram illustrating a serving cell role change procedure according to an embodiment of the present disclosure.

[0089] FIG. 7 is a schematic diagram illustrating a serving cell role change procedure according to an embodiment of the present disclosure.

[0090] FIG. 8 is a block diagram of a system for wireless communication according to an embodiment of the present disclosure.

DETAIEED DESCRIPTION OF EMBODIMENTS

[0091] Embodiments of the present disclosure are described in detail with the technical matters, structural features, achieved objects, and effects with reference to the accompanying drawings as follows. Specifically, the terminologies in the embodiments of the present disclosure are merely for describing the purpose of the certain embodiment, but not to limit the disclosure.

[0092] In a 3rd generation partnership project (3GPP) system, a user equipment (UE) is accessing to a network in a primary cell (PCell), and the UE is also configured with a common search space set in the PCell. When the UE is in a connected mode, the UE continues monitoring one or more physical downlink control channels (PDCCHs) in the CSS in the PCell, and the UE also monitors a connection quality in the PCell, e.g., radio link failure monitoring. To increase a UE throughput, the network may additionally configure the UE with additional serving cell to the PCell. The additional one or more serving cells can be called secondary cells (SCells). The PCell controls a UE connection status, e.g., if the PCell has a connection loss, the UE will lose the connection status and the SCell connection will be automatically cancelled. In some cases, if the network wants to shut down a serving cell for the reason of power saving, the network might have difficulty in shutting down the PCell for a UE or some UEs. This is because as long as the Pcell is off, the UE may immediately lose the connection. In this case, the cost to reduce a network power saving is to degrade a UE user experience, which is not a good solution.

[0093] In this disclosure, some embodiments present a method, which allows a network to shut down a PCell while still maintains a connection for a UE or some UEs. In some embodiments, the general concept of this exemplary method is that the network may trigger to switch a role between a PCell and a SCell, so that the PCell will become (is to be) a SCell and the SCell will become (is to be) a PCell. As long as the PCell is not switched off, the UE can continue maintaining connection mode. Further, the network can switch off the serving cell it aims to turn off.

[0094] FIG. 1 illustrates that, in some embodiments, one or more user equipments (UEs) 10 and a base station (e.g., gNB or eNB) 20 for transmission adjustment in a communication network system 30 (e.g., non-terrestrial network (NTN) or terrestrial network) according to an embodiment of the present disclosure are provided. The communication network system 30 includes the one or more UEs 10 and the base station 20. The one or more UEs 10 may include a memory 12, a transceiver 13, and a processor 11 coupled to the memory 12 and the transceiver 13. The base station 20 may include a memory 22, a transceiver 23, and a processor 21 coupled to the memory 22 and the transceiver 23. The processor 11 or 21 may be configured to implement proposed functions, procedures and/or methods described in this description. Layers of radio interface protocol may be implemented in the processor 11 or 21. The memory 12 or 22 is operatively coupled with the processor 11 or 21 and stores a variety of information to operate the processor 11 or 21. The transceiver 13 or 23 is operatively coupled with the processor 11 or 21, and the transceiver 13 or 23 transmits and/or receives a radio signal.

[0095] The processor 11 or 21 may include application-specific integrated circuit (ASIC), other chipset, logic circuit and/or data processing device. The memory 12 or 22 may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium and/or other storage device. The transceiver 13 or 23 may include baseband circuitry to process radio frequency signals. When the embodiments are implemented in software, the techniques described herein can be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The modules can be stored in the memory 12 or 22 and executed by the processor 11 or 21. The memory 12 or 22 can be implemented within the processor 11 or 21 or external to the processor 11 or 21 in which case those can be communicatively coupled to the processor 11 or 21 via various means as is known in the art. [0096] In some embodiments, the processor 11 is configured by the base station 20, with a first serving cell and a second serving cell, and the transceiver 13 is configured to receive from the base station 20, a first information, wherein the first information is relevant to a role change between the first serving cell and the second serving cell. This can provide a network power saving, allow a network to shut down a first serving cell such as a primary cell (PCell) while still maintain a connection for a UE, provide a good communication performance, and/or provide high reliability.

[0097] In some embodiments, the processor 21 configures to the user equipment (UE) 10, a first serving cell and a second serving cell, and the transceiver 23 is configured to transmit, to the UE 10, a first information, wherein the first information is relevant to a role change between the first serving cell and the second serving cell. This can provide a network power saving, allow a network to shut down a first serving cell such as a primary cell (PCell) while still maintain a connection for a UE, provide a good communication performance, and/or provide high reliability.

[0098] FIG. 2 illustrates a method 200 of wireless communication by a user equipment (UE) according to an embodiment of the present disclosure. In some embodiments, the method 200 includes: a block 202, being configured by a base station, with a first serving cell and a second serving cell, and a block 204, receiving from the base station, a first information, wherein the first information is relevant to a role change between the first serving cell and the second serving cell. This can provide a network power saving, allow a network to shut down a first serving cell such as a primary cell (PCell) while still maintain a connection for a UE, provide a good communication performance, and/or provide high reliability.

[0099] In some embodiments, the UE is configured to receive the first information from the first serving cell or the second serving cell. In some embodiments, the first serving cell is a primary cell (PCell), and the second serving cell is a first secondary cell (SCell) or a first primary secondary cell group (SCG) cell (PSCell). In some embodiments, the UE is further configured by the base station, with a third serving cell, and the UE is configured to receive the first information from the first serving cell, the second serving cell, or the third serving cell. In some embodiments, the first serving cell is a PCell, the second serving cell is a first SCell or a first PSCell, and the third serving cell is a second SCell. In some embodiments, the role change between the first serving cell and the second serving cell comprises that the second seving cell is to be the PCell and/or a current PCell is to be a SCell.

[0100] In some embodiments, the first information comprises a synchronization signal block (SSB) related information, a system information block typel (SIB1) relevant information, a common search space (CSS) set configuration, and/or a PCell role change command. In some embodiments, the SSB related information comprises a frequency location and/or one or more SSB indexes. In some embodiments, the SSB frequency location comprises a global synchronization channel number (GSCN) value. In some embodiments, one or more SSBs of the SSB related information are transmitted in the second serving cell. In some embodiments, an SIB1 of the SIB1 relevant information is transmitted in the second serving cell as a PCell. In some embodiments, a CSS of the CSS set configuration comprises at least one of the followings: a typed CSS, a type 0A CSS, a typel CSS, a type 2 CSS, or type 3 CSS. [0101] In some embodiments, the CSS set configuration configures one or more CSS monitoring occasions in the second serving cell for the UE. In some embodiments, the method further comprises starting to monitor one or more physical downlink control channels (PDCCHs) in configured one or more CSS sets after the role change between the first serving cell and the second serving cell is performed. In some embodiments, the PCell role change command provides information about a cell identifier (ID) of the second serving cell, where the cell ID is physical cell ID or a SCell index. In some embodiments, the method further comprises transmitting a second information to the base station after receiving the first information from the base station. In some embodiments, the second information is transmitted to the first serving cell or the second serving cell. In some embodiments, the second information is used to inform the base station to start the role change between the first serving cell and the second serving cell.

[0102] In some embodiments, the second information comprises a physical random access channel (PRACH) transmission performed by the UE. In some embodiments, the PRACH transmission is contention based or contention free. In some embodiments, when the PRACH transmission is contention based, the UE selects one or more PRACH resources among a set of PRACH resources. In some embodiments, the set of PRACH resources is pre-configured by the base station. In some embodiments, a PRACH resource configuration of the PRACH transmission is transmitted in a system information, in the first information, or in a UE dedicated radio resource control (RRC) signaling. In some embodiments, when the PRACH transmission is contention free, a PRACH preamble or a time-frequency resource is configured by the base station for the UE to transmit the PRACH transmission.

[0103] In some embodiments, the second information is conveyed in a physical uplink shared channel (PUSCH) in one or more symbols in time domain and/or in one or more resource blocks in frequency domain. In some embodiments, PUSCH resources are selected by the UE in a set of PUSCH resources preconfigured by the base station. In some embodiments, PUSCH resources are scheduled by a first downlink control information (DCI). In some embodiments, the first DCI is detected by the UE and is transmitted from the second serving cell. In some embodiments, the method further comprises monitoring a response carrying a third information from the second serving cell after transmitting the second information. In some embodiments, when the response is received by the UE, the UE assumes that the role change between the first serving cell and the second serving cell is performed.

[0104] In some embodiments, the third information is carried in a physical downlink shared channel (PDSCH) scheduled by a second DCI from the first SCell. In some embodiments, the DCI is cyclic redundancy check (CRC) scrambled with a radio network temporary identifier (RNTI). In some embodiments, an RNTI value is relevant to the PRACH resource, or the RNTI value is pre-defined, preconfigured, or a cell-RNTI (C-RNTI). In some embodiments, after the UE receives the third information, the UE considers that the role change between the first serving cell and the second serving cell is performed. In some embodiments, when the UE determines that the role change between the first serving cell and the second serving cell is performed, the UE treats the first SCell as the PCell. [0105] FIG. 3 illustrates a method 300 of wireless communication by a base station according to an embodiment of the present disclosure. In some embodiments, the method 300 includes: a block 302, configuring, to a user equipment (UE), a first serving cell and a second serving cell, and a block 304, transmitting, to the UE, a first information, wherein the first information is relevant to a role change between the first serving cell and the second serving cell. This can provide a network power saving, allow a network to shut down a first serving cell such as a primary cell (PCell) while still maintain a connection for a UE, provide a good communication performance, and/or provide high reliability.

[0106] In some embodiments, the first serving cell or the second serving cell is configured to transmit the first information from to the UE. In some embodiments, the first serving cell is a primary cell (PCell), and the second serving cell is a first secondary cell (SCell) or a first primary secondary cell group (SCG) cell (PSCell). In some embodiments, the base station further configures, to the UE a third serving cell, and the first serving cell, the second serving cell, or the third serving cell is configured to transmit, to the UE, the first information from. In some embodiments, the first serving cell is a PCell, the second serving cell is a first SCell or a first PSCell, and the third serving cell is a second SCell. In some embodiments, the role change between the first serving cell and the second serving cell comprises that the second seving cell is to be the PCell and/or a current PCell is to be a SCell. In some embodiments, the first information comprises a synchronization signal block (SSB) related information, a system information block typel (SIB 1) relevant information, a common search space (CSS) set configuration, and/or a PCell role change command.

[0107] In some embodiments, the SSB related information comprises a frequency location and/or one or more SSB indexes. In some embodiments, the SSB frequency location comprises a global synchronization channel number (GSCN) value. In some embodiments, one or more SSBs of the SSB related information are transmitted in the second serving cell. In some embodiments, an SIB1 of the SIB1 relevant information is transmitted in the second serving cell as a PCell. In some embodiments, a CSS of the CSS set configuration comprises at least one of the followings: a typeO CSS, a type 0A CSS, a typel CSS, a type 2 CSS, or type 3 CSS. In some embodiments, the CSS set configuration configures one or more CSS monitoring occasions in the second serving cell for the UE. In some embodiments, the method further comprises controlling the UE to start to monitor one or more physical downlink control channels (PDCCHs) in configured one or more CSS sets after the role change between the first serving cell and the second serving cell is performed.

[0108] In some embodiments, the PCell role change command provides information about a cell identifier (ID) of the second serving cell, where the cell ID is physical cell ID or a SCell index. In some embodiments, the method further comprises receiving a second information from the UE after transmitting the first information to the UE. In some embodiments, the second information is transmitted to the first serving cell or the second serving cell. In some embodiments, the second information is used to inform the base station to start the role change between the first serving cell and the second serving cell. In some embodiments, the second information comprises a physical random access channel (PRACH) transmission performed by the UE. In some embodiments, the PRACH transmission is contention based or contention free. In some embodiments, when the PRACH transmission is contention based, the base station controls the UE to select one or more PRACH resources among a set of PRACH resources.

[0109] In some embodiments, the set of PRACH resources is pre-configured by the base station. In some embodiments, a PRACH resource configuration of the PRACH transmission is transmitted in a system information, in the first information, or in a UE dedicated radio resource control (RRC) signaling. In some embodiments, when the PRACH transmission is contention free, a PRACH preamble or a time-frequency resource is configured by the base station for the UE to transmit the PRACH transmission. In some embodiments, the second information is conveyed in a physical uplink shared channel (PUSCH) in one or more symbols in time domain and/or in one or more resource blocks in frequency domain. In some embodiments, PUSCH resources are selected by the UE in a set of PUSCH resources pre-configured by the base station. In some embodiments, PUSCH resources are scheduled by a first downlink control information (DO). In some embodiments, the first DCI is detected by the UE and is transmitted from the second serving cell.

[0110] In some embodiments, the method further comprises controlling the UE to monitor a response carrying a third information from the second serving cell after transmitting the second information. In some embodiments, when the response is received by the UE, the base station controls the UE to assume that the role change between the first serving cell and the second serving cell is performed. In some embodiments, the third information is carried in a physical downlink shared channel (PDSCH) scheduled by a second DCI from the first SCell. In some embodiments, the DCI is cyclic redundancy check (CRC) scrambled with a radio network temporary identifier (RNTI). In some embodiments, an RNTI value is relevant to the PRACH resource, or the RNTI value is pre-defined, pre-configured, or a cell-RNTI (C-RNTI). In some embodiments, after the third information is received by the UE, the base station controls the UE to consider that the role change between the first serving cell and the second serving cell is performed. In some embodiments, when the base station controls the UE to determine that the role change between the first serving cell and the second serving cell is performed, the base station controls the UE to treat the first SCell as the PCell.

[0111] The examples given in this disclosure can be applied for loT device or NB-IoT UE in NTN systems, but the method is not exclusively restricted to NTN system nor for loT devices or NB-IoT UE. The examples given in this disclosure can be applied for NR systems, LTE systems, or NB-IoT systems. Further, some examples in the present disclosure can be applied for NB-IoT system, the PDCCH is equivalent to NB-PDCCH (NPDCCH) and the PDSCH is equivalent to NB-PDSCH (NPDSCH).

[0112] Example:

[0113] In a communication system, as illustrated in FIG. 5, when a UE is configured with more than one serving cell, where there is one primary cell (PCell) and there is one secondary cell (SCell) or a PSCell. If a network wants to switch off the PCell for the reason of power saving, it still needs to ensure a continuous service for the UE. However, the network cannot simply switch off the PCell and leave the SCell or the PSCell as the only serving cell for the connected UE. In some exemplary methods, some examples present a mechanism that the network can switch the role of between the PCell and a SCell or a PSCell (in case the UE is configured with more than one SCell or PSCell). Further, a SCell or a PSCell will become (is to be) a PCell, and the previous PCell will become (is to be) a SCell or a PSCell. After that, the network can switch off the SCell or the PSCell without causing any connection problem for the UE.

[0114] In some examples, a UE is configured by a network with a PCell and a first SCell or a PSCell. The UE may receive a first information from the network, where the first information may be transmitted in the PCell, in the first SCell or the PSCell, or in a second SCell as illustrated in FIG. 6.

[0115] The first information may contain a message relevant to a PCell role changing. In some examples, the message informs the UE that the first SCell or the PSCell is to be a PCell and/or the current PCell is to be a SCell or a PSCell. In some examples according to the previous examples, the first information may contain an SSB related information, e.g., an SSB frequency location and/or one or more SSB indexes. The SSB frequency location may be a GSCN value and the SSBs are transmitted in the first SCell or the PSCell. Optionally, the first information may contain SIB 1 relevant information where the SIB 1 is transmitted in the first SCell or the PSCell as a PCell. Optionally, the first information may contain common search space (CSS) set configuration, where the CSS contains at least one of the followings: typeO CSS, type 0A CSS, typel CSS, type 2 CSS, or type 3 CSS. The CSS set configuration configures one or more CSS monitoring occasions in the first SCell or the PSCell for the UE. In some examples, the UE starts to monitor PDCCHs in the configured one or more CSS sets after the PCell role change procedure is complete.

[0116] Optionally, the first information contains a PCell role change command, which further provides information about a cell ID of the first SCell or the PSCell, where the cell ID is physical cell ID, a SCell index, or a PSCell index.

[0117] In some examples, after receiving the first information, the UE sends a second information to the network, where the second information is transmitted to the PCell or the first SCell or the PSCell as illustrated in FIG. 7. In some examples, the second information is used to inform the network to start the PCell role change procedure. In some examples, the second information may be a PRACH transmission performed by the UE. The PRACH transmission may be contention based, where the UE may select one or more PRACH resources among a set of PRACH resources, where the set of PRACH resources may be preconfigured by the network. The PRACH resource configuration may be transmitted in a system information or in the first information or in a UE dedicated RRC signaling.

[0118] Optionally, the PRACH transmission may be contention free, where the network configures a PRACH preamble or time-frequency resource for the UE to transmit the PRACH. In some examples, the second information is conveyed in a PUSCH in one or more symbols in time domain and in one or more resource blocks in frequency domain, where the PUSCH resources may be selected by the UE in a set of PUSCH resources pre-configured by the network. Optionally, the PUSCH resources may be scheduled by a DCI, where the DCI is detected by the UE and it is transmitted from the network, e.g., the first SCell or the PSCell.

[0119] In some examples, after sending the second information, the UE may monitor a response from the first SCell or the PSCell. The response carries a third information. When the response is received by the UE, the UE will assume that the PCell role change procedure is complete. It is to say that the first SCell or the PSCell becomes (is treated as) the PCell. In some examples, the third information is carried in a PDSCH scheduled by a DO from the first SCell or the PSCell. Optionally, the DCI is CRC scrambled with a RNTI whose value is relevant to the PRACH resource according to the previous example. Optionally, the RNTI value is pre-defined or pre-configured or C-RNTI. In some examples, after UE receives the third information, the UE considers that the role switching procedure is complete. The UE treats the first SCell or the PSCell as a PCell.

[0120] Commercial interests for some embodiments are as follows. 1. Providing a network power saving. 2. Allowing a network to shut down a first serving cell such as a primary cell (PCell) while still maintaining a connection for a UE. 3. Providing a good communication performance. 4. Providing a high reliability. 5. Some embodiments of the present disclosure are used by 5G-NR chipset vendors, V2X communication system development vendors, automakers including cars, trains, trucks, buses, bicycles, moto-bikes, helmets, and etc., drones (unmanned aerial vehicles), smartphone makers, communication devices for public safety use, AR/VR device maker for example gaming, conference/seminar, education purposes. Some embodiments of the present disclosure are a combination of “techniques/processes” that can be adopted in 3GPP specification to create an end product. Some embodiments of the present disclosure could be adopted in 5G NR licensed and non-licensed or shared spectrum communications. Some embodiments of the present disclosure propose technical mechanisms.

[0121] FIG. 8 is a block diagram of an example system 700 for wireless communication according to an embodiment of the present disclosure. Embodiments described herein may be implemented into the system using any suitably configured hardware and/or software. FIG. 8 illustrates the system 700 including a radio frequency (RF) circuitry 710, a baseband circuitry 720, an application circuitry 730, a memory/storage 740, a display 750, a camera 760, a sensor 770, and an input/output (I/O) interface 780, coupled with each other at least as illustrated. The application circuitry 730 may include a circuitry such as, but not limited to, one or more single-core or multi-core processors. The processors may include any combination of general- purpose processors and dedicated processors, such as graphics processors, application processors. The processors may be coupled with the memory/storage and configured to execute instructions stored in the memory/storage to enable various applications and/or operating systems running on the system.

[0122] The baseband circuitry 720 may include circuitry such as, but not limited to, one or more singlecore or multi-core processors. The processors may include a baseband processor. The baseband circuitry may handle various radio control functions that enables communication with one or more radio networks via the RF circuitry. The radio control functions may include, but are not limited to, signal modulation, encoding, decoding, radio frequency shifting, etc. In some embodiments, the baseband circuitry may provide for communication compatible with one or more radio technologies. For example, in some embodiments, the baseband circuitry may support communication with an evolved universal terrestrial radio access network (EUTRAN) and/or other wireless metropolitan area networks (WMAN), a wireless local area network (WLAN), a wireless personal area network (WPAN). Embodiments in which the baseband circuitry is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry.

[0123] In various embodiments, the baseband circuitry 720 may include circuitry to operate with signals that are not strictly considered as being in a baseband frequency. For example, in some embodiments, baseband circuitry may include circuitry to operate with signals having an intermediate frequency, which is between a baseband frequency and a radio frequency. The RF circuitry 710 may enable communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry may include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. In various embodiments, the RF circuitry 710 may include circuitry to operate with signals that are not strictly considered as being in a radio frequency. For example, in some embodiments, RF circuitry may include circuitry to operate with signals having an intermediate frequency, which is between a baseband frequency and a radio frequency.

[0124] In various embodiments, the transmitter circuitry, control circuitry, or receiver circuitry discussed above with respect to the user equipment, eNB, or gNB may be embodied in whole or in part in one or more of the RF circuitry, the baseband circuitry, and/or the application circuitry. As used herein, “circuitry” may refer to, be part of, or include an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group), and/or a memory (shared, dedicated, or group) that execute one or more software or firmware programs, a combinational logic circuit, and/or other suitable hardware components that provide the described functionality. In some embodiments, the electronic device circuitry may be implemented in, or functions associated with the circuitry may be implemented by, one or more software or firmware modules. In some embodiments, some or all of the constituent components of the baseband circuitry, the application circuitry, and/or the memory/storage may be implemented together on a system on a chip (SOC). The memory/storage 740 may be used to load and store data and/or instructions, for example, for system. The memory/storage for one embodiment may include any combination of suitable volatile memory, such as dynamic random access memory (DRAM)), and/or non-volatile memory, such as flash memory.

[0125] In various embodiments, the I/O interface 780 may include one or more user interfaces designed to enable user interaction with the system and/or peripheral component interfaces designed to enable peripheral component interaction with the system. User interfaces may include, but are not limited to a physical keyboard or keypad, a touchpad, a speaker, a microphone, etc. Peripheral component interfaces may include, but are not limited to, a non-volatile memory port, a universal serial bus (USB) port, an audio jack, and a power supply interface. In various embodiments, the sensor 770 may include one or more sensing devices to determine environmental conditions and/or location information related to the system. In some embodiments, the sensors may include, but are not limited to, a gyro sensor, an accelerometer, a proximity sensor, an ambient light sensor, and a positioning unit. The positioning unit may also be part of, or interact with, the baseband circuitry and/or RF circuitry to communicate with components of a positioning network, e.g., a global positioning system (GPS) satellite. [0126] In various embodiments, the display 750 may include a display, such as a liquid crystal display and a touch screen display. In various embodiments, the system 700 may be a mobile computing device such as, but not limited to, a laptop computing device, a tablet computing device, a netbook, an ultrabook, a smartphone, an AR/VR glasses, etc. In various embodiments, system may have more or less components, and/or different architectures. Where appropriate, methods described herein may be implemented as a computer program. The computer program may be stored on a storage medium, such as a non-transitory storage medium.

[0127] A person having ordinary skill in the art understands that each of the units, algorithm, and steps described and disclosed in the embodiments of the present disclosure are realized using electronic hardware or combinations of software for computers and electronic hardware. Whether the functions run in hardware or software depends on the condition of application and design requirement for a technical plan. A person having ordinary skill in the art can use different ways to realize the function for each specific application while such realizations should not go beyond the scope of the present disclosure. It is understood by a person having ordinary skill in the art that he/she can refer to the working processes of the system, device, and unit in the above-mentioned embodiment since the working processes of the above-mentioned system, device, and unit are basically the same. For easy description and simplicity, these working processes will not be detailed.

[0128] It is understood that the disclosed system, device, and method in the embodiments of the present disclosure can be realized with other ways. The above-mentioned embodiments are exemplary only. The division of the units is merely based on logical functions while other divisions exist in realization. It is possible that a plurality of units or components are combined or integrated in another system. It is also possible that some characteristics are omitted or skipped. On the other hand, the displayed or discussed mutual coupling, direct coupling, or communicative coupling operate through some ports, devices, or units whether indirectly or communicatively by ways of electrical, mechanical, or other kinds of forms.

[0129] The units as separating components for explanation are or are not physically separated. The units for display are or are not physical units, that is, located in one place or distributed on a plurality of network units. Some or all of the units are used according to the purposes of the embodiments. Moreover, each of the functional units in each of the embodiments can be integrated in one processing unit, physically independent, or integrated in one processing unit with two or more than two units.

[0130] If the software function unit is realized and used and sold as a product, it can be stored in a readable storage medium in a computer. Based on this understanding, the technical plan proposed by the present disclosure can be essentially or partially realized as the form of a software product. Or, one part of the technical plan beneficial to the conventional technology can be realized as the form of a software product. The software product in the computer is stored in a storage medium, including a plurality of commands for a computational device (such as a personal computer, a server, or a network device) to run all or some of the steps disclosed by the embodiments of the present disclosure. The storage medium includes a USB disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a floppy disk, or other kinds of media capable of storing program codes.

[0131] While the present disclosure has been described in connection with what is considered the most practical and preferred embodiments, it is understood that the present disclosure is not limited to the disclosed embodiments but is intended to cover various arrangements made without departing from the scope of the broadest interpretation of the appended claims.

Claims

What is claimed is:

1. A wireless communication method by a user equipment (UE), comprising: being configured by a base station, with a first serving cell and a second serving cell; and receiving from the base station, a first information, wherein the first information is relevant to a role change between the first serving cell and the second serving cell.

2. The method of claim 1 , wherein the UE is configured to receive the first information from the first serving cell or the second serving cell.

3. The method of claim 1 or 2, wherein the first serving cell is a primary cell (PCell), and the second serving cell is a first secondary cell (SCell) or a first primary secondary cell group (SCG) cell (PSCell).

4. The method of claim 1 , wherein the UE is further configured by the base station, with a third serving cell, and the UE is configured to receive the first information from the first serving cell, the second serving cell, or the third serving cell.

5. The method of claim 4, wherein the first serving cell is a PCell, the second serving cell is a first SCell or a first PSCell, and the third serving cell is a second SCell.

6. The method of claim 3 or 5, wherein the role change between the first serving cell and the second serving cell comprises that the second seving cell is to be the PCell and/or a current PCell is to be a SCell.

7. The method of any one of claims 3 to 6, wherein the first information comprises a synchronization signal block (SSB) related information, a system information block typel (SIB1) relevant information, a common search space (CSS) set configuration, and/or a PCell role change command.

8. The method of any one of claims 3 to 7, wherein further comprising transmitting a second information to the base station after receiving the first information from the base station.

9. The method of claim 8, wherein the second information is transmitted to the first serving cell or the second serving cell.

10. The method of claim 8 or 9, wherein the second information is used to inform the base station to start the role change between the first serving cell and the second serving cell.

11. The method of any one of claim 8 to 10, wherein the second information comprises a physical random access channel (PRACH) transmission performed by the UE.

12. The method of any one of claim 8 to 10, wherein the second information is conveyed in a physical uplink shared channel (PUSCH) in one or more symbols in time domain and/or in one or more resource blocks in frequency domain.

13. The method of any one of claims 8 to 12, further comprising monitoring a response carrying a third information from the second serving cell after transmitting the second information.

14. The method of claim 13, wherein when the response is received by the UE, the UE assumes that the role change between the first serving cell and the second serving cell is performed.

15. The method of claim 13 or 14, wherein the third information is carried in a physical downlink shared channel (PDSCH) scheduled by a second DO from the first SCell.

16. The method of any one of claims 13 to 15, wherein after the UE receives the third information, the UE considers that the role change between the first serving cell and the second serving cell is performed.

17. The method of any one of claims 3 to 16, wherein when the UE determines that the role change between the first serving cell and the second serving cell is performed, the UE treats the first SCell as the PCell.

18. A wireless communication method by a base station, comprising: configuring, to a user equipment (UE), a first serving cell and a second serving cell; and transmitting, to the UE, a first information, wherein the first information is relevant to a role change between the first serving cell and the second serving cell.

19. A user equipment (UE), comprising: a memory; a transceiver; and a processor coupled to the memory and the transceiver; wherein the processor is configured to perform the method of any one of claims 1 to 17.

20. A base station, comprising: a memory; a transceiver; and a processor coupled to the memory and the transceiver; wherein the processor is configured to perform the method of claim 18.