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KR-20260068056-A - Method and device for lower-layer triggered mobility in a wireless communication system

KR20260068056AKR 20260068056 AKR20260068056 AKR 20260068056AKR-20260068056-A

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting higher data transfer rates. A UE includes a transceiver configured to receive a Radio Resource Control (RRC) reset message containing a setting for at least one lower-layer triggered mobility (LTM) candidate cell, and to receive an LTM switching command Media Access Control (MAC) control element (CE) indicating to perform an LTM cell switching to the LTM candidate cell among the at least one LTM candidate cell. The transceiver is also configured to transmit a Random Access (RA) preamble to the LTM candidate cell indicated by the MAC CE a number of N repetitions. The UE also includes a processor operably connected to the transceiver. The processor is configured to monitor a Physical Downlink Control Channel (PDCCH) for a Random Access response after the RA preamble has been transmitted N times.

Inventors

  • 아지왈 아닐

Assignees

  • 삼성전자주식회사

Dates

Publication Date
20260513
Application Date
20240913
Priority Date
20240906

Claims (15)

  1. A method performed by a user terminal (UE) in a wireless communication system, A step of identifying that the random access procedure has not been completed; A step of identifying whether a preamble transmission counter is equal to a specific value when a random access preamble is repeatedly transmitted and no contention-free random access resource for the random access procedure is provided; and A method performed by a user terminal (UE) in a wireless communication system, comprising the step of selecting a set of random access resources for a random access procedure when the preamble transmission counter is equal to the specific value and a set of random access resources associated with a higher message 1 repetition count is available.
  2. In paragraph 1, A method performed by a user terminal (UE) in a wireless communication system, wherein the above specific value is equal to the maximum number of random access preamble transmissions containing message 1 repetition plus 1.
  3. In paragraph 1, A method performed by a user terminal (UE) in a wireless communication system, wherein the above specific value is equal to twice the maximum number of random access preamble transmissions containing message 1 repetition plus 1.
  4. In paragraph 1, The above identifying step includes the step of identifying that the time duration associated with the random access procedure has expired, and A method performed by a user terminal (UE) in a wireless communication system, wherein the above time duration includes a contention resolution timer or a random access response window.
  5. In paragraph 1, A method performed by a user terminal (UE) in a wireless communication system, wherein the type of random access procedure described above is set to 4-step random access.
  6. In paragraph 1, A method performed by a user terminal (UE) in a wireless communication system, further comprising the step of transmitting a random access preamble to a base station a higher number of message repetitions in a set of physical random access channel (PRACH) time points.
  7. In paragraph 1, A method performed by a user terminal (UE) in a wireless communication system, wherein the set of random access resources is associated with the next highest number of message 1 repetitions after the current set of random access resources.
  8. As a user terminal (UE) in a wireless communication system, transceiver; and It includes a controller connected to the above transceiver, and The above controller is: Identify that the random access procedure has not been completed, and When a random access preamble is repeatedly transmitted and a contention-free random access resource for the random access procedure is not provided, identify whether the preamble transmission counter is equal to a specific value, and, A user terminal (UE) in a wireless communication system configured to select the set of random access resources for the random access procedure when the preamble transmission counter is equal to the specific value and a set of random access resources associated with a higher message 1 repetition count is available.
  9. In paragraph 8, A user terminal (UE) in a wireless communication system, wherein the above specific value is equal to the maximum number of random access preamble transmissions containing message 1 repetition plus 1.
  10. In paragraph 8, A user terminal (UE) in a wireless communication system, wherein the above specific value is equal to twice the maximum number of random access preamble transmissions containing message 1 repetition plus 1.
  11. In paragraph 8, The above controller is additionally configured to identify that the time duration associated with the above random access procedure has expired, and, A user terminal (UE) in a wireless communication system, wherein the above time duration includes a contention resolution timer.
  12. In paragraph 8, The above controller is additionally configured to identify that the time duration associated with the above random access procedure has expired, and, A user terminal (UE) in a wireless communication system, wherein the above time duration includes a random access response window.
  13. In paragraph 8, A user terminal (UE) in a wireless communication system, wherein the type of the above random access procedure is set to 4-stage random access.
  14. In paragraph 8, The above controller is: A user terminal (UE) in a wireless communication system, additionally configured to transmit a random access preamble to a base station a higher number of message repetitions in a set of physical random access channel (PRACH) times.
  15. In paragraph 8, A user terminal (UE) in a wireless communication system, wherein the set of random access resources is associated with the next highest number of message 1 repetitions after the current set of random access resources.

Description

Method and device for lower-layer triggered mobility in a wireless communication system The present disclosure generally relates to wireless networks, wireless communication systems, or mobile communication systems. More specifically, the present disclosure relates to lower-layer triggered mobility in wireless communication systems. 5G mobile communication technology defines a wide frequency band to enable fast transmission speeds and new services, and can be implemented not only in frequency bands below 6 GHz ('Sub 6 GHz'), such as 3.5 gigahertz (3.5 GHz), but also in ultra-high frequency bands called millimeter waves (mmWave), such as 28 GHz and 39 GHz ('Above 6 GHz'). In addition, for 6G mobile communication technology, which is referred to as a system beyond 5G, implementation in the terahertz (THX) band (e.g., the 3 terahertz band at 95 GHz) is being considered to achieve transmission speeds 50 times faster and ultra-low latency reduced to one-tenth compared to 5G mobile communication technology. In the early stages of 5G mobile communication technology, aiming to satisfy service support and performance requirements for enhanced Mobile BroadBand (eMBB), Ultra-Reliable Low-Latency Communications (URLLC), and massive Machine-Type Communications (mMTC), technologies such as beamforming and Massive MIMO to mitigate path loss and increase transmission distance in ultra-high frequency bands, support for various numerologies (such as the operation of multiple subcarrier spacings) and dynamic operation of slot formats for the efficient utilization of ultra-high frequency resources, initial access techniques to support multi-beam transmission and broadband, definition and operation of Band-Width Parts (BWP), Low Density Parity Check (LDPC) codes for high-volume data transmission, new channel coding methods such as Polar Codes for the reliable transmission of control information, and L2 pre-processing (L2 Standardization has been carried out for pre-processing, network slicing which provides a dedicated network specialized for specific services, and other methods. Currently, discussions are underway to improve and enhance the performance of the initial 5G mobile communication technology, taking into account the services that the 5G mobile communication technology was intended to support. Additionally, standardization of the physical layer is in progress for technologies such as V2X (Vehicle-to-Everything), which helps autonomous vehicles make driving decisions and enhance user convenience based on their own location and status information transmitted by the vehicle; NR-U (New Radio Unlicensed), which aims for system operation in unlicensed bands to comply with various regulatory requirements; NR terminal low power consumption technology (UE Power Saving); Non-Terrestrial Network (NTN), which is direct terminal-satellite communication for securing coverage in areas where communication with the terrestrial network is impossible; and positioning. In addition, standardization is underway in the field of wireless interface architecture/protocols for technologies such as the Industrial Internet of Things (IIoT) for supporting new services through linkage and convergence with other industries, Integrated Access and Backhaul (IAB) which provides nodes for expanding network service areas by integrating wireless backhaul links and access links, Mobility Enhancement including Conditional Handover and Dual Active Protocol Stack (DAPS) Handover, and 2-step Random Access (2-step RACH for NR) which simplifies random access procedures. Standardization is also underway in the field of system architecture/services for 5G baseline architectures (e.g., Service based Architecture, Service based Interface) for incorporating Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC), which provides services based on the location of the terminal. When such 5G mobile communication systems are commercialized, connected devices, which are increasing explosively, will be connected to communication networks. Accordingly, it is expected that there will be a need to enhance the functionality and performance of 5G mobile communication systems and to integrate the operation of connected devices. To this end, new research is planned to be conducted on 5G performance improvement and complexity reduction, support for AI services, support for metaverse services, and drone communication using eXtended Reality (XR), Artificial Intelligence (AI), and Machine Learning (ML) to efficiently support Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR). Furthermore, the advancement of these 5G mobile communication systems encompasses multi-antenna transmission technologies such as new waveforms to guarantee coverage in the terahertz band of 6G mobile communication technology, Full Dimensional MIMO (FD-MIMO), array antennas, and large-scale antennas; metamaterial-based lenses and