Uplink Control Information Reporting in LAA Secondary Cell Groups
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently and flexibly reporting uplink control information (UCI) with licensed-assisted access (LAA) uplink transmissions, particularly due to unreliable unlicensed access and fixed association timing, which can lead to performance issues and reduced spectrum efficiency.
Innovation Solution
The implementation of methods and systems that configure user equipment (UE) with a secondary cell group and licensed-assisted access serving cell, determining the appropriate channel and timing for UCI reporting based on reception timing and scheduling information, allowing for flexible UCI reporting on either licensed or unlicensed cells, and aggregating HARQ-ACK feedback across multiple subframes to ensure reliable and efficient transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed association timing is used for UCI reporting, then the system structure is simple, but the spectrum efficiency and reliability are reduced due to unreliable unlicensed access
Solution Approach 1:
The patent implements dynamic UCI reporting by allowing flexible selection of reporting timing and cell based on channel conditions and scheduling information. The UE can dynamically determine whether to report UCI on licensed or unlicensed cells and adjust reporting timing based on reception timing of PDSCH and scheduling information, thereby adapting to unreliable unlicensed access conditions while maintaining system reliability.
2Productivity
If UCI is reported on unlicensed cells, then spectrum efficiency may be improved, but reliability deteriorates due to unreliable unlicensed access
Solution Approach 1:
The patent applies local quality by allowing different reporting strategies for different cells based on their characteristics. Licensed cells provide reliable reporting when unlicensed access is poor, while unlicensed cells are utilized when channel conditions are good. The system selectively uses licensed or unlicensed cells for UCI reporting based on local channel conditions, achieving both high reliability and spectrum efficiency.
Solution Approach 2:
Licensed cells act as intermediary backup resources for UCI reporting. When unlicensed cell access is unreliable, the system can fall back to licensed cells for UCI transmission, ensuring that reporting reliability is maintained while still attempting to utilize unlicensed spectrum for improved efficiency when conditions permit.
3Reliability
If flexible UCI reporting on either licensed or unlicensed cells is implemented, then spectrum efficiency and reliability are improved, but device complexity increases
Solution Approach 1:
The patent implements preliminary action by pre-configuring the UE with multiple serving cells (both licensed and unlicensed) and their associated parameters before UCI reporting is needed. The network provides scheduling information and cell configuration in advance, allowing the UE to quickly determine the appropriate reporting cell and timing without complex real-time decision-making, thereby reducing UE complexity while maintaining flexibility.
Data Source
AI summary
A user equipment (UE) is described that includes a processor. The UE is configured with a secondary cell group (SCG). The UE is also configured with a licensed-assisted access (LAA) serving cell as a primary secondary cell (pSCell) of the SCG. The UE receives a physical downlink shared channel (PDSCH) on at least one LAA serving cell in the SCG. The UE determines a channel to carry uplink control information (UCI), the channel being on any one of the serving cell(s) in the SCG. The UE also determines transmission timing of the channel based on reception timing of the PDSCH. The UE further determines one or more PDSCHs of which HARQ-ACK bits are included in the UCI, the one or more PDSCHs including the PDSCH. The UE additionally determines content of the HARQ-ACK bits. The UE also performs a channel access procedure for the transmission of the channel.