US 11272535

US patent 11272535, titled "Method and apparatus for LBT failure detection," was granted to Hannibal IP LLC. The inventors are Hung-Chen Chen, Chie-Ming Chou, Chia-Hung Wei, and Mei-Ju Shih. The patent was filed on January 8, 2020, and issued on March 8, 2022.

Abstract:
The patent describes a method for Listen-Before-Talk (LBT) failure detection in a User Equipment (UE). This method involves a Medium Access Control (MAC) entity of the UE receiving an LBT failure indication from a lower layer for all uplink (UL) transmissions. An LBT failure counter is increased upon receiving this indication. An LBT failure event is determined to have occurred when the counter meets or exceeds a defined threshold. The LBT failure counter is reset if the MAC entity has not received an LBT failure indication for a specified time period.

Plain-language overview of independent claims:

• Claim 1 (User Equipment - UE): This claim describes a User Equipment (UE) designed to detect Listen-Before-Talk (LBT) failures. The UE includes a processor and computer-readable memory. The processor is set up to:

  1. Receive a signal indicating an LBT failure from a lower layer (e.g., the physical layer) for any type of uplink (UL) transmission.
  2. Increase an LBT failure counter when this LBT failure signal is received.
  3. Determine that a serious "LBT failure event" has happened if this counter reaches or goes above a pre-set limit (threshold).
  4. Reset the LBT failure counter specifically when an upper layer (like the Radio Resource Control, RRC, layer) requests the MAC entity to be reset.

• Claim 10 (Method): This claim outlines a method performed by a User Equipment (UE) for detecting Listen-Before-Talk (LBT) failures. The method involves:

  1. A MAC entity within the UE receiving an LBT failure signal from a lower layer for any type of uplink (UL) transmission.
  2. Increasing an LBT failure counter when the MAC entity receives this LBT failure signal.
  3. Determining that an "LBT failure event" has occurred when the LBT failure counter is greater than or equal to a specified threshold.
  4. Resetting the LBT failure counter when an upper layer of the UE requests a reset of the MAC entity.

Legal Status and Litigation:
The patent US11272535B2 is currently active and is set to expire on February 16, 2040.
Public records indicate that this patent family has been involved in litigation:

• A PTAB case, IPR2025-01188, was filed and subsequently settled.
• A US case was filed in the Texas Eastern District Court, identified as 4:25-cv-00200.
• The first worldwide family litigation has also been filed.

As of April 26, 2026, searches of the USPTO and CAFC dockets for patent 11272535 did not yield further specific updates on the statuses of IPR2025-01188 or case 4:25-cv-00200 beyond what is stated in the patent's metadata. General information about the functioning of these dockets was found, but no direct current status reports for these specific cases.