Uplink LBT Failure Detection in 5G Unlicensed Band Terminals
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Solution Overview
Problem
In wireless communication systems using 3GPP 5G new radio (NR) technology, there is a challenge in detecting uplink listen-before-talk (LBT) failures due to interference from other devices in unlicensed bands, which affects transmission reliability and connectivity.
Innovation Solution
A method is provided for a terminal in a wireless communication system to detect uplink LBT failures by receiving configuration information related to LBT failures, performing LBT procedures for a first bandwidth part (BWP) on a cell, identifying LBT failures, and indicating such failures to an upper layer when the primary cell experiences failures across all BWPs configured with physical random access channel (PRACH) resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LBT procedure is performed for uplink transmission in unlicensed band, then transmission reliability is improved, but detection precision of LBT failure is worsened due to interference from other devices
Solution Approach 1:
The patent introduces a dedicated detection channel as an intermediary mechanism to monitor LBT failure conditions. This detection channel separately observes the channel state without requiring the terminal to actually transmit on the uplink channel, thereby accurately detecting LBT failures caused by interference from other devices while maintaining transmission reliability through the LBT procedure.
2Adaptability or versatility
If multiple BWPs are configured for uplink transmission, then adaptability is improved, but device complexity is worsened due to need to monitor LBT failure across all BWPs
Solution Approach 1:
The patent segments the LBT failure detection process by BWP (bandwidth part). Instead of monitoring all BWPs simultaneously which would increase complexity, the terminal performs LBT procedures and monitors for failures independently on each BWP. The MAC entity then determines overall LBT failure based on the segmented results from individual BWPs, thereby managing complexity while maintaining adaptability.
Solution Approach 2:
The patent applies partial action by requiring LBT failure detection only for BWPs that have PRACH (physical random access channel) resources configured. Not all BWPs need to be monitored for LBT failure, only those with relevant uplink access capabilities, thereby reducing the complexity burden while maintaining sufficient adaptability for the intended communication scenarios.
3Ease of operation
If LBT failure detection is performed only when needed, then ease of operation is improved, but reliability is worsened due to delayed failure detection
Solution Approach 1:
The patent implements preliminary action by having the terminal perform LBT procedures and monitor for failures before actual uplink transmission occurs. The MAC entity continuously monitors the channel state during LBT procedure execution, so when interference from other devices is detected, the failure is identified immediately at the detection timing rather than after transmission attempts fail, thereby ensuring timely reliability while maintaining operational simplicity.
Data Source
AI summary
The disclosure relates to a communication technique for convergence of a 5G communication system for supporting a higher data transmission rate beyond a 4G system with an IoT technology, and a system therefor. The disclosure may be applied to intelligent services (e.g., smart homes, smart buildings, smart cities, smart cars or connected cars, health care, digital education, retail business, security and safety-related services, etc.) based on 5G communication technology and IoT-related technology. The disclosure relates to a method and apparatus for detecting an uplink listen-before-talk (LBT) failure when using a 3GPP 5G new radio (NR) technology in a wireless communication system.