PDCCH Candidate Hopping for Reduced-Capability UE Collision
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Solution Overview
Problem
Reduced capability user equipment (UEs) in wireless communication systems experience increased collisions of physical downlink control channel (PDCCH) candidates due to limited resources, leading to decode errors and inefficient resource utilization.
Innovation Solution
Implementing a PDCCH candidate hopping function that correlates the mapping behavior with changing values over time, such as starting symbol numbers, slot numbers, or system frame numbers, to reduce persistent collisions and improve resource allocation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PDCCH candidates are mapped to CCEs using fixed hashing functions, then the mapping is simple and deterministic, but persistent collisions occur between PDCCH candidates of different UEs
Solution Approach 1:
The patent applies dynamics by making the PDCCH candidate to CCE mapping variable over time through hopping patterns. The mapping relationship changes in different time slots or frames based on hopping parameters, transforming the static hashing function into a dynamic mapping mechanism that adapts to different time instances to avoid persistent collisions
Solution Approach 2:
The patent changes the mapping parameters by introducing hopping patterns that modify the CCE index calculation based on time-varying parameters such as slot number, frame number, or hopping offset. This parameter change approach allows the same PDCCH candidate to map to different CCEs at different times, reducing collision probability while maintaining deterministic mapping within each time instance
2Device complexity
If reduced capability UEs monitor fewer PDCCH candidates to conserve resources, then device complexity is reduced, but collision probability increases
Solution Approach 1:
The hopping mechanism provides dynamic time-domain separation where reduced capability UEs can monitor fewer candidates but benefit from time-varying mapping that spreads collisions across different time instances, effectively reducing persistent collision impact on overall reliability
Solution Approach 2:
The patent implements periodic hopping patterns where the mapping relationship cycles through different configurations over time. This periodic action ensures that even with reduced monitoring capacity, UEs can reliably receive PDCCH messages as the system periodically varies the mapping to avoid collisions
3Productivity
If PDCCH candidates are concentrated in limited CCE resources, then resource allocation is efficient, but collisions between multiple UEs increase
Solution Approach 1:
The hopping pattern introduces dynamic time-domain spreading of PDCCH candidates across CCE resources. While spatial concentration is maintained for efficiency, the time-varying mapping distributes the effective usage across different time instances, reducing simultaneous collisions while maintaining overall resource allocation efficiency
Solution Approach 2:
The patent adds a time dimension to the resource allocation by introducing hopping patterns that vary mapping over time slots or frames. This transforms the static two-dimensional mapping (UE to CCE) into a three-dimensional mapping (UE to CCE to time), allowing efficient resource concentration in space while distributing collisions in time
Data Source
AI summary
Methods and apparatuses described herein provide a physical downlink control channel (PDCCH) candidate hopping function that reduces collisions between PDCCH candidates, particularly between PDCCH candidates associated with reduced capability user equipment (UE). For example, the hopping function may be implemented as part of a PDCCH candidate to control channel element (CCE) function or may be applied separately from the PDCCH candidate to CCE function. The hopping function may reduce persistent collisions between PDCCH candidates by correlating the mapping behavior with a value that changes over time. Some techniques and apparatuses described herein provide signaling for configuration and activation/deactivation/modification of the hopping pattern. Thus, collisions between PDCCH candidates are reduced, thereby conserving computing resources and wireless communication resources. Furthermore, the reduction of collisions may improve performance of UEs with reduced PDCCH capabilities, such as reduced-capability UEs. Numerous other aspects are provided.