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EP-4740624-A1 - MANAGING EARLY TIMING ADVANCE ACQUISITION

EP4740624A1EP 4740624 A1EP4740624 A1EP 4740624A1EP-4740624-A1

Abstract

One or more distributed units (DU) of a distributed base station that also includes a central unit (CU) implement the method comprising: transmitting, from a candidate DU to the CU, configuration parameters for early timing advance (TA) acquisition by a user equipment (UE) in a target cell; receiving, at the candidate DU from the UE in the target cell and in accordance with the configuration parameters, a random access preamble; and transmitting, from the candidate DU to the CU, a TA value based on the receiving of the random access preamble.

Inventors

  • WU, CHIH-HSIANG

Assignees

  • GOOGLE LLC

Dates

Publication Date
20260513
Application Date
20240729

Claims (15)

  1. 1. A method implemented in one or more distributed units (DU) of a distributed base station that also includes a central unit (CU), the method comprising: transmitting, from a candidate DU to the CU, configuration parameters for early timing advance (TA) acquisition by a user equipment (UE) in a target cell; receiving, at the candidate DU from the UE in the target cell and in accordance with the configuration parameters, a random access preamble; and transmitting, from the candidate DU to the CU, a TA value based on the receiving of the random access preamble.
  2. 2. The method of claim 1, further comprising: transmitting, from the candidate DU to the CU and prior to the receiving of the random access preamble, a low-layer triggered mobility (LTM) DU configuration related to the target cell.
  3. 3. The method of claim 2, wherein: the transmitting of the LTM DU configuration includes transmitting a UE Context Setup Response message.
  4. 4. The method of any of the preceding claims, wherein: the configuration parameters for the early TA acquisition include a physical random access channel (PRACH) resource.
  5. 5. The method of any of the preceding claims, wherein: the configuration parameters for the early TA acquisition include one or more PRACH occasions.
  6. 6. The method of any of the preceding claims, further comprising, prior to the receiving of the random access preamble: transmitting, from a source DU to the UE, a command instructing the UE to transmit the random access preamble in the target cell.
  7. 7. The method of claim 6, wherein the command instructing the UE to transmit the random access preamble is a physical downlink control channel (PDCCH) order.
  8. 8. The method of claim 6 or 7, further comprising, subsequently to the receiving of the random access preamble: receiving, at the source DU from the UE, a measurement report; and transmitting, from the source DU to the UE, an LTM command to instruct the UE to initiate an LTM cell switch to the target cell.
  9. 9. A method implemented in a central unit (CU) of a distributed base station, the method comprising: receiving, from a candidate DU of the distributed base station, configuration parameters for early timing advance (TA) acquisition by a user equipment (UE) in a target cell; transmitting, to the UE, the configuration parameters; and receiving, from the candidate DU, a TA value generated for the UE in the target cell.
  10. 10. The method of claim 9, wherein: the transmitting of the configuration parameters to the UE includes transmitting the configuration parameters to the UE via a source DU of the distributed base station.
  11. 11. The method of claim 9 or 10, further comprising: receiving, from the candidate DU and prior to the receiving of the random access preamble, a low-layer triggered mobility (LTM) DU configuration related to the target cell.
  12. 12. The method of claim 11, wherein: the receiving of the LTM DU configuration receiving transmitting a UE Context Setup Response message.
  13. 13. The method of any of claims 9-12, wherein: the configuration parameters for the early TA acquisition include a physical random access channel (PRACH) resource.
  14. 14. The method of any of claims 9-13, wherein: the configuration parameters for the early TA acquisition include one or more PRACH occasions.
  15. 15. A node in a distributed base station comprising processing hardware and configured to implement a method of any of the preceding claims.

Description

MANAGING EARLY TIMING ADVANCE ACQUISITION CROSS-REFERENCE TO RELATED APPLICATION [0001] This application claims priority to and the benefit of the filing date of provisional U.S. Patent Application No. 63/516,136 entitled “Managing Early Timing Advance Acquisition,” filed on July 27, 2024. The entire content of the provisional application is hereby expressly incorporated herein by reference FIELD OF THE DISCLOSURE [0002] This disclosure relates to wireless communications and, more particularly, to managing timing advance acquisition for early uplink timing synchronization with a target cell for a UE before the UE connects to the target cell. BACKGROUND [0003] This background description is provided for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. [0004] In telecommunication systems, the Packet Data Convergence Protocol (PDCP) sublayer of the radio protocol stack provides services such as transfer of user-plane data, ciphering, integrity protection, etc. For example, the PDCP layer defined for the Evolved Universal Terrestrial Radio Access (EUTRA) radio interface (see 3GPP specification TS 36.323) and New Radio (NR) (see 3GPP specification TS 38.323) provides sequencing of protocol data units (PDUs) in the uplink direction (from a user device, also known as a user equipment (UE), to a base station) as well as in the downlink direction (from the base station to the UE). Further, the PDCP sublayer provides signaling radio bearers (SRBs) and data radio bearers (DRBs) to the Radio Resource Control (RRC) sublayer. Generally speaking, the UE and a base station can use SRBs to exchange RRC messages as well as non-access stratum (NAS) messages, and can use DRBs to transport data on a user plane. [0005] UEs can use several types of SRBs and DRBs. When operating in dual connectivity (DC), the cells associated with the base station operating the master node (MN) define a master cell group (MCG), and the cells associated with the base station operating as the secondary node (SN) define the secondary cell group (SCG). So-called SRB1 resources carry RRC messages, which in some cases include NAS messages over the dedicated control channel (DCCH), and SRB2 resources support RRC messages that include logged measurement information or NAS messages, also over the DCCH but with lower priority than SRB1 resources. More generally, SRB1 and SRB2 resources allow the UE and the MN to exchange RRC messages related to the MN and embed RRC messages related to the SN, and also can be referred to as MCG SRBs. SRB3 resources allow the UE and the SN to exchange RRC messages related to the SN, and can be referred to as SCG SRBs. Split SRBs allow the UE to exchange RRC messages directly with the MN via lower layer resources of the MN and the SN. Further, DRBs using the lower-layer resources of only the MN can be referred as MCG DRBs, DRBs using the lower-layer resources of only the SN can be referred as SCG DRBs, and DRBs using the lower-layer resources of both the MCG and the SCG can be referred to as split DRBs. [0006] The UE in some scenarios can concurrently utilize resources of multiple radio access network (RAN) nodes (e.g., base stations or components of a distributed base station), interconnected by a backhaul. When these network nodes support different radio access technologies (RATs), this type of connectivity is referred to as Multi-Radio Dual Connectivity (MR-DC). When a UE operates in MR-DC, one base station operates as a master node (MN) that covers a primary cell (PCell), and the other base station operates as a secondary node (SN) that covers a primary secondary cell (PSCell). The UE communicates with the MN (via the PCell) and the SN (via the PSCell). In other scenarios, the UE utilizes resources of one base station at a time. One base station and/or the UE determines that the UE should establish a radio connection with another base station. For example, one base station can determine to hand the UE over to the second base station, and initiate a handover procedure. [0007] When the UE moves from the coverage area of one cell to the coverage area of another cell in a RAN, the UE and the RAN at some point must perform a serving cell change. To this end, the RAN configures the UE to transmit Layer 3 (L3) measurement results. Using the L3 measurement results from the UE, the RAN transmits an RRC reconfiguration message configuring Reconfiguration with Synchronization (e.g., the RRC reconfiguration message includes ^ReconfigurationWithSync IE) for a change of the serving cell (e.g., PCell or PSCell). When the UE operates in carrier aggregation (CA) of at least one secondary cell (SCell) with the PCell or PSCell, the RAN