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EP-4740625-A1 - METHODS AND APPARATUS FOR ENHANCED BEAM REPORTS AND UPLINK SYNCHRONIZATION FOR MOBILITY PROCEDURES IN WIRELESS COMMUNICATION

EP4740625A1EP 4740625 A1EP4740625 A1EP 4740625A1EP-4740625-A1

Abstract

Methods and apparatus are provided for beam reporting and uplink synchronization. A UE is configured to support an uplink procedure that is after a cell switch command reception. Methods are also provided for differential encoding and handling PRACH overlap with uplink transmissions on a serving cell.

Inventors

  • HE, HONG
  • ZENG, WEI
  • YE, CHUNXUAN
  • ZHANG, DAWEI
  • WU, DAN
  • CUI, JIE
  • NIU, HUANING

Assignees

  • Apple Inc.

Dates

Publication Date
20260513
Application Date
20240809

Claims (20)

  1. 1. A method for a user equipment (UE) to perform uplink (UL) synchronization with a candidate cell, the method comprising: receiving, from a base station, a cell switch command (CSC) media access control (MAC) control element (MAC-CE); when the CSC MAC-CE includes a timing advance (TA) field indicator (TAFI) field set to a first value, or when the CSC MAC-CE does not include the TAFI field: determining a first TA value from a TA field of the CSC MAC-CE; and using the first TA value to adjust UL timing for an UL transmission on the candidate cell; and when the CSC MAC-CE includes the TAFI field set to a second value: determining a synchronization signal/physical broadcast channel block (SSB) index and a preamble index from the TA field of the CSC MAC-CE; using the SSB index and the preamble index associated with the SSB index to perform a physical random access channel (PRACH) procedure with the candidate cell to obtain a second TA value; and using the second TA value to adjust the UL timing for the UL transmission on the candidate cell.
  2. 2. The method of claim 1, wherein the TAFI field comprises a single bit, and wherein the TA field comprises 12 bits.
  3. 3. The method of claim 2, wherein when the TAFI field is set to the first value, or when the CSC MAC-CE does not include the TAFI field, the 12 bits of the TA field indicate the first TA value, and wherein when the TAFI field is set to the second value, a first six bits of the 12 bits of the TA field indicate an SSB index value and a second 6 bits of the 12 bits of the TA field indicate a preamble index value.
  4. 4. The method of claim 1, wherein the candidate cell is configured with a lower layer- triggered mobility (LTM) operation.
  5. 5. The method of claim 1, further comprising receiving, from the base station, before receiving the CSC MAC-CE, a physical downlink control channel (PDCCH) order instructing the UE to perform the PRACH procedure.
  6. 6. The method of claim 1, wherein the PRACH procedure comprises a contention free random access (CFRA) procedure.
  7. 7. A method for a base station in a wireless network, the method comprising: configuring, for a user equipment (UE), a cell switch command (CSC) media access control (MAC) control element (MAC-CE) to include, during a lower layer- triggered mobility (LTM) operation by one or more candidate cells, a timing advance (TA) field indicator (TAFI) field; in response to a measurement report from the UE: determining to perform the LTM operation for a candidate cell of the one or more candidate cells; and transmitting, to the UE, the CSC MAC-CE comprising the TAFI field to indicate whether a TA field of the CSC MAC-CE includes: a TA value; or a synchronization signal/physical broadcast channel block (SSB) index and a preamble index; and receiving, from the UE, an LTM completion message.
  8. 8. The method of claim 7, wherein configuring the CSC MAC-CE comprises transmitting, to the UE, a radio resource control (RRC) signal comprising LTM configuration information.
  9. 9. The method of claim 7, wherein the TAFI field comprises a single bit, and wherein the TA field comprises 12 bits.
  10. 10. The method of claim 9, wherein when the TAFI field is set to a first value, the 12 bits of the TA field indicate the TA value, and wherein when the TAFI field is set to a second value, a first six bits of the 12 bits of the TA field indicate an SSB index value and a second 6 bits of the 12 bits of the TA field indicate a preamble index value.
  11. 11. The method of claim 7, further comprising transmitting, to the UE, before transmitting the CSC MAC-CE, a physical downlink control channel (PDCCH) order instructing the UE to perform a physical random access channel (PRACH) procedure.
  12. 12. The method of claim 11, wherein the PRACH procedure comprises a contention free random access (CFRA) procedure.
  13. 13. A method for a user equipment (UE) to perform uplink (UL) synchronization with a candidate cell, the method comprising: receiving, from a base station, a radio resource control (RRC) signal comprising a synchronization signal/physical broadcast channel block (SSB) resource list; receiving, from the base station, a cell switch command (CSC) media access control (MAC) control element (MAC-CE) indicating a transmission configuration indicator (TCI)-state; determining an SSB index, from a TCI-state list, of a corresponding SSB that is used as a quasi co-located (QCL) source reference signal (RS) for the TCI-state indicated in the CSC MAC-CE; determining a preamble index associated with the SSB index; performing, using the SSB index and the preamble index, to perform a physical random access channel (PRACH) procedure with the candidate cell to obtain a timing advance (TA) value; and using the TA value to adjust UL timing for an UL transmission on the candidate cell.
  14. 14. The method of claim 13, wherein the SSB resource list comprises a list of contention free random access (CFRA) SSB resources, where each CFRA SSB resource comprises respective SSB indexes and respective associated preamble indexes.
  15. 15. The method of claim 14, wherein the RRC signal further comprises a PRACH mask index to apply to the preamble indexes of the CFRA SSB resources in the SSB resource list.
  16. 16. The method of claim 13, wherein the candidate cell is configured with a lower layer- triggered mobility (LTM) operation.
  17. 17. The method of claim 13, further comprising receiving, from the base station, before receiving the CSC MAC-CE, a physical downlink control channel (PDCCH) order instructing the UE to perform the PRACH procedure.
  18. 18. The method of claim 13, wherein the PRACH procedure comprises a contention free random access (CFRA) procedure.
  19. 19. A method for a base station in a wireless network, the method comprising: transmitting, to a user equipment (UE), a radio resource control (RRC) signal comprising a synchronization signal/physical broadcast channel block (SSB) resource list; configuring a transmission configuration indicator (TCI)-state list, wherein a TCI-state in the TCI-state list is configured an SSB index for a corresponding SSB that is used as a quasi co-located (QCL) source reference signal (RS); and transmitting, to the UE, a cell switch command (CSC) media access control (MAC) control element (MAC-CE) indicating the TCI-state that is used by the UE to determine the SSB index and a corresponding preamble index associated with the SSB index based on the SSB resource list.
  20. 20. The method of claim 19, wherein the SSB resource list comprises a list of contention free random access (CFRA) SSB resources where each CFRA SSB resource comprises respective SSB indexes and respective associated preamble indexes.

Description

METHODS AND APPARATUS FOR ENHANCED BEAM REPORTS AND UPLINK SYNCHRONIZATION FOR MOBILITY PROCEDURES IN WIRELESS COMMUNICATION TECHNICAL.FIELD [0001] This application relates generally to wireless communication systems, including beam reporting and uplink synchronization. BACKGROUND [0002] Wireless mobile communication technology uses various standards and protocols to transmit data between a base station and a wireless communication device. Wireless communication system standards and protocols can include, for example, 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) (e.g., 4G), 3GPP New Radio (NR) (e.g., 5G), and Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard for Wireless Local Area Networks (WLAN) (commonly known to industry groups as Wi-Fi®). [0003] As contemplated by the 3GPP, different wireless communication systems' standards and protocols can use various radio access networks (RANs) for communicating between a base station of the RAN (which may also sometimes be referred to generally as a RAN node, a network node, or simply a node) and a wireless communication device known as a user equipment (UE). 3GPP RANs can include, for example, Global System for Mobile communications (GSM), Enhanced Data Rates for GSM Evolution (EDGE) RAN (GERAN), Universal Terrestrial Radio Access Network (UTRAN), Evolved Universal Terrestrial Radio Access Network (E-UTRAN), and/or Next- Generation Radio Access Network (NG-RAN). [0004] Each RAN may use one or more radio access technologies (RATs) to perform communication between the base station and the UE. For example, the GERAN implements GSM and/or EDGE RAT, the UTRAN implements Universal Mobile Telecommunication System (UMTS) RAT or other 3GPP RAT, the E-UTRAN implements LTE RAT (sometimes simply referred to as LTE), and NG-RAN implements NR RAT (sometimes referred to herein as 5G RAT, 5GNR RAT, or simply NR). In certain deployments, the E-UTRAN may also implement NR RAT. In certain deployments, NG-RAN may also implement LTE RAT. [0005] A base station used by a RAN may correspond to that RAN. One example of an E-UTRAN base station is an Evolved Universal Terrestrial Radio Access Network (E- UTRAN) Node B (also commonly denoted as evolved Node B, enhanced Node B, eNodeB, or eNB). One example of an NG-RAN base station is a next generation Node B (also sometimes referred to as a g Node B or gNB). [0006] A RAN provides its communication services with external entities through its connection to a core network (CN). For example, E-UTRAN may utilize an Evolved Packet Core (EPC) while NG-RAN may utilize a 5G Core Network (5GC). [0007] Frequency bands for 5G NR may be separated into two or more different frequency ranges. For example, Frequency Range 1 (FR1) may include frequency bands operating in sub-6 gigahertz (GHz) frequencies, some of which are bands that may be used by previous standards, and may potentially be extended to cover new spectrum offerings from 410 megahertz (MHz) to 7125 MHz. Frequency Range 2 (FR2) may include frequency bands from 24.25 GHz to 52.6 GHz. Note that in some systems, FR2 may also include frequency bands from 52.6 GHz to 71 GHz (or beyond). Bands in the millimeter wave (mmWave) range of FR2 may have smaller coverage but potentially higher available bandwidth than bands in FR1. Skilled persons will recognize these frequency ranges, which are provided by way of example, may change from time to time or from region to region. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS [0008] To easily identify the discussion of any particular element or act, the most significant digit or digits in a reference number refer to the figure number in which that element is first introduced. [0009] FIG. 1 illustrates a triggering CFRA procedure by a CSC MAC-CE for candidate cells, according to one embodiment. [0010] FIG. 2 illustrates a flowchart of a method for a UE to perform UL synchronization with a candidate cell, according to certain embodiments herein. [0011] FIG. 3 illustrates a flowchart of a method for a base station in a wireless network, according to certain embodiments herein. [0012] FIG. 4 illustrates a CFRA resource selection process based on TCLstate information in a CSC MAC-CE, according to one embodiment. [0013] FIG. 5 illustrates a flowchart of a method for a UE to perform UL synchronization with a candidate cell, according to certain embodiments herein. [0014] FIG. 6 illustrates a flowchart of a method for a base station in a wireless network, according to certain embodiments herein. [0015] FIG. 7 illustrates a procedure for PRACH RO selection for LTM, according to certain embodiments. [0016] FIG. 8 illustrates a flowchart of a method of a UE to perform UL synchronization with a candidate cell, according to certain embodiments herein. [0017] FIG. 9A illustrates an Ll-RSRP encoding scheme for candidate cell reporting, according to one embodiment. [0018] FIG. 9B illustrates an Ll-RSRP encoding scheme