Cross-Carrier Cell Scheduling for PCell Control Channel Capacity
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Solution Overview
Problem
Existing 5G NR systems face limitations in determining efficient cell scheduling modes, particularly for primary cells (Pcells), as they can only be self-scheduled and lack effective methods for cross-carrier scheduling by secondary cells (Scells), leading to insufficient bandwidth and control channel overheads.
Innovation Solution
A method and apparatus for determining a cell scheduling mode that allows secondary cells to schedule primary cells by configuring high-band carriers for Scells, utilizing scheduling configuration information and activity states to enable cross-carrier scheduling, including common and UE-specific search spaces, and managing scheduling modes through RNTI scrambling and timer-based transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If primary cells are configured to be self-scheduled only, then scheduling simplicity is maintained, but control channel capacity and bandwidth utilization are insufficient
Solution Approach 1:
The patent inverts the conventional scheduling relationship by allowing secondary cells (Scells) to schedule primary cells (Pcells) through cross-carrier scheduling. This is achieved by configuring a Scell as a scheduling cell for a Pcell, where the Scell transmits PDCCH for both itself and the Pcell, thereby increasing control channel capacity without adding more Pcells
Solution Approach 2:
The patent enables Scells to perform multiple functions: they serve as data transmission cells, self-scheduling cells, and cross-carrier scheduling cells for Pcells. This multi-functionality allows the Scell to schedule both its own PDSCH and the Pcell's PDSCH, optimizing resource utilization and reducing control channel overhead
2Productivity
If cross-carrier scheduling is enabled for primary cells, then control channel capacity increases, but scheduling mode determination complexity increases
Solution Approach 1:
The patent implements dynamic scheduling mode determination based on the activity state of the scheduling cell. When the Scell is active, cross-carrier scheduling is enabled; when the Scell becomes inactive or enters dormancy, the system automatically switches to self-scheduling mode for the Pcell. This dynamic adaptation reduces complexity by only enabling cross-carrier scheduling when beneficial
Solution Approach 2:
The system continuously monitors the activity state of the Scell and uses this feedback to determine the appropriate scheduling mode for the Pcell. The terminal device reports scheduling mode indication information based on the Scell's activity state, creating a closed-loop control mechanism that automatically adjusts scheduling modes to optimize performance while managing complexity
3Productivity
If secondary cells use high-band carriers for cross-carrier scheduling, then bandwidth utilization improves, but control channel overhead increases
Solution Approach 1:
The patent merges the control channels by allowing the Scell to transmit PDCCH for both its own PDSCH and the Pcell's PDSCH. This consolidation reduces the total number of separate control channels needed, as the Scell's PDCCH resources serve dual purposes, thereby reducing control channel overhead while maintaining high bandwidth utilization through high-band carrier usage
Data Source
AI summary
A method for determining a cell scheduling mode includes: receiving scheduling configuration information, where the scheduling configuration information indicates that a second cell of the terminal is scheduled by a first cell of the terminal and that the second cell is capable of self-scheduling; determining an activity state of the first cell; and determining a scheduling mode for the second cell based on the scheduling configuration information and the activity state.