Listen Before Talk Procedure in Wireless Device
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently managing carrier aggregation and Listen Before Talk (LBT) procedures, particularly in unlicensed spectrum, leading to inefficiencies in channel access and resource allocation, which affects network performance and fairness in multi-user scenarios.
Innovation Solution
The implementation of advanced LBT mechanisms, such as adaptive energy detection thresholds and random back-off procedures, along with optimized carrier aggregation techniques, enables efficient channel access and resource allocation in unlicensed spectrum, ensuring fair coexistence with other technologies and improving network performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LBT procedure is performed before each uplink transmission in unlicensed spectrum, then channel access fairness is improved, but transmission delay increases
Solution Approach 1:
The patent applies preliminary action by performing LBT procedure in advance during subframe n-1 (prior subframe) before the actual uplink transmission in subframe n. This allows the channel access decision to be made beforehand, reducing the delay at the time of actual transmission while ensuring fair channel access through proper LBT execution in the preceding subframe.
2Productivity
If carrier aggregation is implemented with multiple cells, then network capacity is improved, but system complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the carrier aggregation system into licensed cells and unlicensed cells, each with distinct LBT handling mechanisms. Licensed cells follow traditional scheduling while unlicensed cells implement autonomous LBT-based access. This segmentation allows the system to handle multiple carriers efficiently without uniformly increasing complexity across all cells, as each cell type can be managed independently with appropriate LBT strategies.
Data Source
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AI summary
A wireless device receives an uplink grant for a licensed assisted access (LAA) cell. The uplink grant comprises a physical uplink shared channel (PUSCH) starting position field and a listen-before-talk (LBT) type field. The PUSCH starting position field indicates a PUSCH starting position in a subframe of the LAA cell. The LBT type field indicates at least one of a first LBT type or a second LBT type for the subframe. A determination is made based, at least, on uplink transmissions by the wireless device in a preceding adjacent subframe of the LAA cell, to: perform an LBT procedure for transmission of uplink signals in the subframe, or transmit the uplink signals without performing the LBT procedure for the subframe, regardless of the LBT type field indicating the first LBT type or the second LBT type. The uplink signals in the subframe may be transmitted via the LAA cell.