PDCCH Monitoring for Multi-Cell Scheduling With Unified DCI
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Solution Overview
Problem
Legacy 5G NR systems face limitations in PDCCH monitoring due to the inability to efficiently handle multiple DCI format sizes and multi-cell scheduling, leading to increased UE complexity and signaling overhead, particularly in scenarios involving Rel-16 and Rel-17 features and cross-carrier scheduling.
Innovation Solution
The proposed solution involves modifying UE procedures for PDCCH candidate allocation and search space set overbooking, where the number of configured PDCCH candidates is scaled by the number of DCI format sizes, with separate counting per format size, and implementing multi-cell scheduling using a single DCI format to reduce overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate PDCCH monitoring is performed for each DCI format size in legacy systems, then scheduling flexibility is maintained, but UE complexity and signaling overhead increase significantly
Solution Approach 1:
The patent combines multiple DCI format sizes into a unified PDCCH monitoring framework. Instead of separately monitoring PDCCH for each DCI format size (0_0, 0_1, 0_2, 1_0, 1_1, 1_2), the UE is configured with a single search space set that can carry DCI formats of different sizes. The network indicates the actual DCI format size through higher layer parameters, allowing the UE to efficiently monitor without duplicating monitoring procedures for each format size, thereby reducing complexity while preserving scheduling flexibility.
Solution Approach 2:
The search space set is designed to serve multiple DCI format sizes universally. A single search space set configuration can accommodate DCI formats 0_0, 01, 02, 10, 11, and 12, making the monitoring structure multi-functional. This universal approach eliminates the need for separate dedicated search space sets for each DCI format size, reducing overall UE complexity while maintaining the ability to schedule diverse traffic types.
2Adaptability or versatility
If multi-cell scheduling is implemented using multiple DCI formats in legacy systems, then comprehensive scheduling coverage is achieved, but signaling overhead increases
Solution Approach 1:
The patent merges multiple cell scheduling information into a single DCI format. Instead of transmitting separate DCI messages for each cell, the network can indicate scheduling information for multiple cells within one DCI format. The UE monitors a unified search space set that can carry this consolidated multi-cell scheduling DCI, reducing the number of PDCCH candidates and associated signaling overhead while maintaining comprehensive scheduling coverage across multiple cells.
Solution Approach 2:
The DCI format and search space set are designed with multi-functionality to handle both single-cell and multi-cell scheduling scenarios. A single DCI format structure can represent scheduling assignments for one or multiple cells, and the same search space set serves both single-cell and multi-cell scheduling purposes. This universal design reduces signaling overhead by eliminating redundant scheduling messages while preserving full scheduling coverage.
Data Source
AI summary
Methods and apparatuses for physical downlink control channel (PDCCH) monitoring for multi-cell scheduling. A method for a user equipment (UE) includes receiving first information indicating a set of cells that includes more than one cell, second information indicating a first search space set that is associated with a DCI format for scheduling on multiple cells, and third information indicating an indicator value corresponding to the set of cells. The method further includes determining an association between the first search space set and the set of cells, and, based on the first search space set and the indicator value, control channel elements (CCEs) for receptions of PDCCH candidates; and receiving the PDCCH candidates over the CCEs.