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US-20260129706-A1 - METHODS FOR ENHANCED MOBILITY IN WIRELESS SYSTEMS

US20260129706A1US 20260129706 A1US20260129706 A1US 20260129706A1US-20260129706-A1

Abstract

Methods, devices, and systems for communication by a wireless transmit/receive unit (WTRU) associated with a source cell. The WTRU is configured with a conditional reconfiguration which includes a trigger condition and a configured target cell. The WTRU detects an occurrence of an impairment event resulting in impairment to operation of the WTRU in the source cell. If the impairment event satisfies the trigger condition, a reconfiguration is performed with the configured target cell. If the impairment event does not satisfy the trigger condition, a target cell is selected based on a cell selection procedure, and if the WTRU is configured with a conditional reconfiguration for the selected target cell, a reconfiguration is performed with the selected target cell; and if the WTRU is not configured with a conditional reconfiguration for the target cell, a reestablishment is performed with the selected target cell.

Inventors

  • Yugeswar Deenoo Narayanan Thangaraj
  • Mouna Hajir
  • Ghyslain Pelletier

Assignees

  • INTERDIGITAL PATENT HOLDINGS, INC.

Dates

Publication Date
20260507
Application Date
20251219

Claims (20)

  1. 1 . A method for communication by a wireless transmit/receive unit (WTRU) associated with a source cell, the method comprising: detecting a trigger condition of a conditional handover (CHO) configuration; responsive to the trigger condition, performing a CHO to one of a plurality of target cells of the CHO, the one of the plurality of target cells selected from among the plurality of target cells based on beam quality.
  2. 2 . The method of claim 1 , further comprising removing a stored configuration of the CHO based on completing the CHO, wherein the stored configuration indicates the trigger condition.
  3. 3 . The method of claim 2 , wherein removing the stored configuration of the CHO comprises removing an entry from a conditional reconfiguration variable stored on the WTRU.
  4. 4 . The method of claim 2 , wherein removing the stored configuration of the CHO comprises removing an entry from a VarConditionalReconfig variable.
  5. 5 . The method of claim 2 , wherein removing the stored configuration of the CHO comprises removing an entry matching the trigger condition of the CHO.
  6. 6 . The method of claim 2 , wherein removing the stored configuration of the CHO comprises removing an entry matching a measID corresponding to the trigger condition of the CHO.
  7. 7 . The method of claim 2 , wherein removing the stored configuration of the CHO comprises removing an entry matching the one of the plurality of target cells of the CHO.
  8. 8 . The method of claim 2 , wherein removing the stored configuration of the CHO comprises removing an entry matching a special cell (spCell) variable corresponding to the one of the plurality of target cells of the CHO.
  9. 9 . The method of claim 1 , wherein the trigger condition comprises a threshold quality of a source gNB.
  10. 10 . The method of claim 1 , wherein the trigger condition comprises a radio link failure (RLF).
  11. 11 . A wireless transmit/receive unit (WTRU) associated with a source cell, the WTRU comprising: a transceiver; and a processor; the transceiver and the processor configured to detect a trigger condition of a conditional handover (CHO) configuration; the transceiver and the processor configured to perform, after detecting the trigger condition, a CHO to one of a plurality of target cells of the CHO, the one of the plurality of target cells selected from among the plurality of target cells based on beam quality.
  12. 12 . The WTRU of claim 11 , wherein the transceiver and the processor are configured to remove, based on completing the CHO, a stored configuration of the CHO, wherein the stored configuration indicates the trigger condition.
  13. 13 . The WTRU of claim 12 , wherein removing the stored configuration of the CHO comprises removing an entry from a conditional reconfiguration variable stored on the WTRU.
  14. 14 . The WTRU of claim 12 , wherein removing the stored configuration of the CHO comprises removing an entry from a VarConditionalReconfig variable.
  15. 15 . The WTRU of claim 12 , wherein removing the stored configuration of the CHO comprises removing an entry matching the trigger condition of the CHO.
  16. 16 . The WTRU of claim 12 , wherein removing the stored configuration of the CHO comprises removing an entry matching a measID corresponding to the trigger condition of the CHO.
  17. 17 . The WTRU of claim 12 , wherein removing the stored configuration of the CHO comprises removing an entry matching the one of the plurality of target cells of the CHO.
  18. 18 . The WTRU of claim 12 , wherein removing the stored configuration of the CHO comprises removing an entry matching a special cell (spCell) variable corresponding to the one of the plurality of target cells of the CHO.
  19. 19 . The WTRU of claim 11 , wherein the trigger condition comprises a threshold quality of a source gNB.
  20. 20 . The WTRU of claim 11 , wherein the trigger condition comprises a radio link failure (RLF).

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. patent application Ser. No. 18/141,797 filed May 1, 2023, which is a continuation of U.S. patent application Ser. No. 17/045,027 filed Oct. 2, 2020, which issued as U.S. Pat. No. 11,641,605 on May 2, 2023, which is a National Stage application of PCT/US2019/024397 filed Mar. 27, 2019, which claims the benefit of U.S. Provisional Application No. 62/652,163 filed on Apr. 3, 2018 and 62/736,290 filed Sep. 25, 2018. BACKGROUND Summary Mobile communications are in continuous evolution and mobile networks are at the doorstep of their fifth generation (5G). As with previous generations, new use cases largely contributed in setting the requirements for the new system. The 5G air interface, and its new radio (NR) access technology, is expected to enable use cases such as improved broadband performance (IBB), industrial control and communications (ICC) and vehicular applications (V2X), and massive machine-type communications (mMTC). Methods, devices, and systems for communication by a wireless transmit/receive unit (WTRU) associated with a source cell. The WTRU is configured with a conditional reconfiguration which includes a trigger condition and a configured target cell. The WTRU detects an occurrence of an impairment event resulting in impairment to operation of the WTRU in the source cell. If the impairment event satisfies the trigger condition, a reconfiguration is performed with the configured target cell. If the impairment event does not satisfy the trigger condition, a target cell is selected based on a cell selection procedure, and if the WTRU is configured with a conditional reconfiguration for the selected target cell, a reconfiguration is performed with the selected target cell; and if the WTRU is not configured with a conditional reconfiguration for the target cell, a reestablishment is performed with the selected target cell. BRIEF DESCRIPTION OF THE DRAWINGS A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings, wherein like reference numerals in the figures indicate like elements, and wherein: FIG. 1A is a system diagram illustrating an example communications system in which one or more disclosed embodiments may be implemented; FIG. 1B is a system diagram illustrating an example wireless transmit/receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1A according to an embodiment; FIG. 1C is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communications system illustrated in FIG. 1A according to an embodiment; FIG. 1D is a system diagram illustrating a further example RAN and a further example CN that may be used within the communications system illustrated in FIG. 1A according to an embodiment; FIG. 2 is a diagram illustrating handover failure causes associated with mobility signaling issues; FIG. 3 is a cell diagram which illustrates CFRA resources activated based on their association with a serving beam in a source cell; FIG. 4 is a message sequence chart illustrating a configuration mismatch scenario; and FIG. 5 is a message sequence chart illustrating an example procedure for re-establishment which includes a fallback to a conditional handover. DETAILED DESCRIPTION FIG. 1A is a diagram illustrating an example communications system 100 in which one or more disclosed embodiments may be implemented. The communications system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bank multicarrier (FBMC), and the like. As shown in FIG. 1A, the communications system 100 may include wireless transmit/receive units (WTRUs) 102a, 102b, 102c, 102d, a RAN 104/113, a CN 106/115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and/or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and/or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a “station” and/or a “STA”, may be configured to transmit and/or re