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US-20260129678-A1 - METHODS FOR WIDEBAND UNLICENSED CHANNEL ACCESS

US20260129678A1US 20260129678 A1US20260129678 A1US 20260129678A1US-20260129678-A1

Abstract

Systems, methods, and devices for addressing wideband unlicensed channel access are disclosed herein. A device may be configured for different types of listen-before-talk (LBT) procedures, where the LBT type may refer to the frequency granularity of the LBT. There may be a hierarchical LBT procedure, where the LBT granularity changes at each point in the LBT procedure. There may be a selection of parameters for each LBT type. Some of the parameters may be shared over different points of the LBT procedure. There may be LBT subband sets for a subband set LBT type. There may be one or more indications of acquired LBT subbands on a condition of shared channel occupancy time. At one point in the LBT procedure, there may be a selection of a LBT subband or one or more subbands sets for transmission based on one or more criteria.

Inventors

  • J. Patrick Tooher
  • Oghenekome Oteri
  • Aata EL HAMSS

Assignees

  • INTERDIGITAL PATENT HOLDINGS, INC.

Dates

Publication Date
20260507
Application Date
20251229

Claims (15)

  1. 1 . A wireless transmit/receive unit (WTRU) comprising a transceiver and at least one processor configured to control the transceiver to: perform a hierarchical listen-before-talk (LBT) process for acquiring channel resources, the hierarchical LBT process comprising a plurality of steps; and determine one or more parameters of the hierarchical LBT process based on at least one of: a result of a previous LBT operation, a network configuration, a measurement, or a transmission type.
  2. 2 . The WTRU of claim 1 , wherein the hierarchical LBT process comprises: performing LBT on an entire bandwidth part (BWP); on a condition that the entire BWP is not acquired, performing LBT on one or more subband sets; and on a condition that the one or more subband sets are not acquired, performing LBT on one or more subbands.
  3. 3 . The WTRU of claim 1 , wherein the one or more parameters comprise a number of steps of the hierarchical LBT process.
  4. 4 . The WTRU of claim 1 , wherein the one or more parameters comprise a stopping criterion for the hierarchical LBT process.
  5. 5 . The WTRU of claim 4 , wherein the stopping criterion is satisfied when at least a minimum number of subbands or subband sets has been acquired.
  6. 6 . The WTRU of claim 4 , wherein the stopping criterion is satisfied when a largest contiguous group of subband sets has been acquired.
  7. 7 . The WTRU of claim 1 , wherein the processor is further configured to adjust one or more parameters of a subsequent step of the hierarchical LBT process based on a result of a previous step.
  8. 8 . The WTRU of claim 7 , wherein the one or more adjusted parameters comprise a number of idle clear channel assessment (CCA) slots required.
  9. 9 . The WTRU of claim 7 , wherein the one or more adjusted parameters comprise a contention window size (CWS) or an LBT category.
  10. 10 . The WTRU of claim 1 , wherein the processor is further configured to transmit on channel resources corresponding to one or more acquired bandwidth parts, subband sets, or subbands after completion of the hierarchical LBT process.
  11. 11 . A method performed by a wireless transmit/receive unit (WTRU) for acquiring channel resources, the method comprising: performing a hierarchical listen-before-talk (LBT) process comprising a plurality of steps; and determining one or more parameters of the hierarchical LBT process based on at least one of: a result of a previous LBT operation, a network configuration, a measurement, or a transmission type.
  12. 12 . The method of claim 11 , wherein the hierarchical LBT process comprises performing LBT on an entire bandwidth part (BWP), and if not acquired, performing LBT on one or more subband sets, and if not acquired, performing LBT on one or more subbands.
  13. 13 . The method of claim 11 , wherein the one or more parameters comprise a number of steps of the hierarchical LBT process or a stopping criterion.
  14. 14 . The method of claim 11 , further comprising adjusting one or more parameters of a subsequent step of the hierarchical LBT process based on a result of a previous step.
  15. 15 . The method of claim 14 , wherein the one or more adjusted parameters comprise at least one of: a number of idle clear channel assessment (CCA) slots, a contention window size (CWS), or an LBT category.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. patent application Ser. No. 17/441,765 filed Sep. 22, 2021, which is the U.S. National Stage, under 35 U.S. C. § 371, of International Application No. PCT/US2020/025327 filed Mar. 27, 2020, which claims the benefit of U.S. Provisional Application No. 62/824,799 filed Mar. 27, 2019, the contents of which are incorporated herein by reference. BACKGROUND Using large bandwidths in new radio in unlicensed bands (NR-U) is beneficial because it ensures that large transmissions take place in short amounts of time. This, in turn, reduces the impact of failing to acquire a channel due to listen-before-talk (LBT) not being successful in the allotted time. LBT may be done in portions of at least 20 MHz. If the LBT process is defined to only be performed on LBT subbands, multiple LBT processes would need to be performed to acquire a large bandwidth (BW). This may increase channel access complexity. For example, it is unclear how many LBT processes can be performed in parallel. Using a wideband LBT process may reduce the undue complexity. However, a wideband LBT process may fail for the entire BW or bandwidth part (BWP) when only a small portion of the BW is actually occupied. Therefore, adaptability between these two extreme examples is required to benefit from both the reduced complexity of wideband LBT and the greater access granularity of subband LBT. Additionally, it may be beneficial to ensure that all acquired LBT subbands form a contiguous BW. Therefore, rules may be required when acquiring the channel to ensure that the union of acquired LBT subbands form a contiguous set. SUMMARY Systems, methods, and devices for addressing wideband unlicensed channel access are disclosed herein. A device may be configured for different types of listen-before-talk (LBT) procedures, where the LBT type may refer to the frequency granularity of the LBT. There may be a hierarchical LBT procedure, where the LBT granularity changes at each point in the LBT procedure. There may be a selection of parameters for each LBT type. Some of the parameters may be shared over different points of the LBT procedure. There may be LBT subband sets for a subband set LBT type. There may be one or more indications of acquired LBT subbands on a condition of shared channel occupancy time. At one point in the LBT procedure, there may be a selection of a LBT subband or one or more subbands sets for transmission based on one or more criteria. A wireless transmit/receive unit (WTRU) may be configured to perform the disclosed hierarchical LBT procedure. In the hierarchical LBT procedure, the WTRU may change the LBT type at different levels of the process. For example, the WTRU may first perform LBT to acquire available resources on an entire bandwidth part (BWP). If the BWP is not acquired, the WTRU may then perform LBT to acquire resources on one or more subband sets. If one or more subband sets are not acquired, the WTRU may then perform LBT to acquire available resources on one or more subbands. After every LBT attempt on a different LBT type, data may be transmitted if a sufficient number of resources have been acquired. Resources comprising one or more subband sets may be determined by at least one of previous LBT operation, network configuration, measurements, and transmission type. Performing LBT on one or more subband sets may include adjusting at least one LBT parameter, where the at least one LBT parameter may be a number of idle clear channel assessment (CCA) slots required. The hierarchical LBT procedure may further comprise monitoring multiple LBT subbands for a discovery reference signal (DRS) and transmitting a physical random access channel (PRACH) on an acquired LBT subband. 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 examples of different LBT types covering a whole bandwidth part (BWP); FIG. 3 is a flow chart illustrating an example of hierarchical LBT with a transmission possibility after every L