IP Verse

Method And Apparatus For Lbt Failure Detection

Patent No. US11272535 (titled "Method And Apparatus For Lbt Failure Detection") was filed by Hannibal Ip Llc on Jan 8, 2020.

What is this patent about?

’535 is related to the field of wireless communication, specifically addressing the problem of Listen-Before-Talk (LBT) failures in next-generation (5G NR) networks operating on unlicensed spectrum. Before a User Equipment (UE) transmits on unlicensed spectrum, it must perform LBT to ensure it doesn't interfere with other devices. The background highlights the need for UEs to efficiently handle LBT failures, which can disrupt uplink transmissions.

The underlying idea behind ’535 is to implement a mechanism within the UE's Medium Access Control (MAC) layer to detect and react to persistent LBT failures. The UE maintains an LBT failure counter that increments each time the physical layer reports a failure. By comparing this counter to a threshold, the MAC layer can determine when a significant LBT failure event has occurred, signaling a potential problem with the radio link.

The claims of ’535 focus on a UE configured to: receive LBT failure indications from the physical layer for all uplink transmissions; increment an LBT failure counter upon receiving such an indication; determine an LBT failure event when the counter reaches a threshold; and reset the counter when the MAC layer is reset by a higher layer. This mechanism allows the UE to track and respond to persistent LBT failures .

In practice, the UE's physical layer attempts an uplink transmission and, if it fails the LBT check, sends a failure indication to the MAC layer. The MAC layer then increments the LBT failure counter. If the counter exceeds a configured threshold, the MAC layer determines that an LBT failure event has occurred. The MAC layer then may report this event to the Radio Resource Control (RRC) layer, which can trigger actions like switching to a different bandwidth part or initiating a radio link failure recovery procedure. The LBT failure counter is reset when the MAC layer itself is reset by the RRC layer.

This approach differs from prior solutions by providing a structured way for the UE to detect and react to persistent LBT failures. Instead of simply retrying transmissions, the UE uses the LBT failure counter and threshold to identify a more fundamental problem. This allows the UE to take more drastic actions, such as switching to a different channel or initiating a re-establishment procedure, which can improve the overall reliability and performance of the wireless connection. The MAC layer reset provides a clean slate after a failure event.

How does this patent fit in bigger picture?

Technical landscape at the time

In the late 2010s when ’535 was filed, wireless communication systems commonly relied on Listen-Before-Talk (LBT) mechanisms to manage channel access, especially in unlicensed spectrums. At a time when carrier aggregation was typically implemented using LTE in both licensed and unlicensed bands, ensuring coexistence with other technologies like Wi-Fi was a key consideration. When hardware or software constraints made efficient handling of LBT failures non-trivial, especially in the context of uplink transmissions.

Novelty and Inventive Step

The claims were amended during prosecution. Arguments were presented by the applicant in response to rejections based on 35 U.S.C. 102 and 103. The examiner issued a final rejection. The prosecution record does describe claim changes and technical reasoning that led to the rejection.

Claims

This patent contains 20 claims, with independent claims 1 and 10. The independent claims are directed to a user equipment and a method for Listen-Before-Talk (LBT) failure detection. The dependent claims generally elaborate on specific aspects, features, or steps related to the LBT failure detection and handling procedures.

Key Claim Terms New

Definitions of key terms used in the patent claims.

Term (Source)Support for SpecificationInterpretation
LBT failure counter
(Claim 1, Claim 10)		“According to an aspect of the present disclosure, a UE is provided. The UE includes one or more non-transitory computer-readable media having computer-executable instructions embodied thereon and at least one processor coupled to the one or more non-transitory computer-readable media. The at least one processor is configured to execute the computer-executable instructions to: increase an LBT failure counter when the MAC entity receives the LBT failure indication; determine an LBT failure event occurs when the LBT failure counter is greater than or equal to a threshold; and reset the LBT failure counter after the MAC entity has not received the LBT failure indication for a time period.”A counter that is incremented when the MAC entity receives the LBT failure indication and reset when a reset of the MAC entity is requested by an upper layer of the UE.
LBT failure event
(Claim 1, Claim 10)		“According to an aspect of the present disclosure, a UE is provided. The UE includes one or more non-transitory computer-readable media having computer-executable instructions embodied thereon and at least one processor coupled to the one or more non-transitory computer-readable media. The at least one processor is configured to execute the computer-executable instructions to: increase an LBT failure counter when the MAC entity receives the LBT failure indication; determine an LBT failure event occurs when the LBT failure counter is greater than or equal to a threshold; and reset the LBT failure counter after the MAC entity has not received the LBT failure indication for a time period.”An event that occurs when the LBT failure counter is greater than or equal to a threshold.
Listen-Before-Talk (LBT) failure indication
(Claim 1, Claim 10)		“The present disclosure is directed to a method for LBT failure detection performed by a UE in the next generation wireless communication networks. LBT is a mechanism by which a wireless device applies Clear Channel Assessment (CCA) before using the channel.”An indication of LBT failure received by the MAC entity from a lower layer for all UL transmissions.
Medium Access Control (MAC) entity
(Claim 1, Claim 10)		“According to an aspect of the present disclosure, a UE is provided. The UE includes one or more non-transitory computer-readable media having computer-executable instructions embodied thereon and at least one processor coupled to the one or more non-transitory computer-readable media. The at least one processor is configured to execute the computer-executable instructions to: receive, by a Medium Access Control (MAC) entity of the UE, an LBT failure indication from a lower layer for all UL transmissions; increase an LBT failure counter when the MAC entity receives the LBT failure indication; determine an LBT failure event occurs when the LBT failure counter is greater than or equal to a threshold; and reset the LBT failure counter after the MAC entity has not received the LBT failure indication for a time period.”A MAC entity of the UE that receives the LBT failure indication from a lower layer for all UL transmissions.

Litigation Cases New

US Latest litigation cases involving this patent.

Case NumberFiling DateTitle
4:25-cv-00200Feb 27, 2025Hannibal IP, LLC v. Samsung Electronics Co., Ltd. et al

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US11272535

HANNIBAL IP LLC
Application Number
US16737787
Filing Date
Jan 8, 2020
Status
Granted
Expiry Date
Feb 16, 2040
External Links
Slate, USPTO, Google Patents