PDCCH Search Space Allocation Based on Channel Quality Indicators
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Solution Overview
Problem
Current 5G NR and other wireless communication systems face challenges in efficiently scheduling the physical downlink control channel due to collisions and decoding failures, especially when channel quality indicators (CQIs) are unreliable, leading to suboptimal resource allocation and interference between user equipment (UE) specific and common search spaces.
Innovation Solution
The base station dynamically determines and allocates channel resource elements (CCEs) based on received CQIs from user equipment (UEs), shifting scheduling from UE-specific to common search spaces when collisions or decoding failures occur, and adjusts aggregation levels to ensure reliable downlink control information transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the base station schedules PDCCH in UE-specific search space based on CQI, then resource allocation efficiency is improved, but decoding reliability deteriorates when CQI is unreliable
Solution Approach 1:
The base station dynamically switches between UE-specific search space scheduling (when CQI is reliable) and common search space scheduling (when CQI is unreliable or collisions occur). This dynamic adaptation allows the system to optimize resource allocation efficiency while maintaining decoding reliability by selecting the appropriate search space type based on real-time channel conditions and collision detection results.
2Object-generated harmful factors
If the base station uses UE-specific search space for PDCCH allocation, then interference between UEs is reduced, but collision with common search space increases
Solution Approach 1:
The base station acts as an intermediary that monitors for collisions between UE-specific and common search spaces. When a collision is detected or CQI decoding fails, the system transitions to using common search space for PDCCH allocation, thereby avoiding the harmful collision effect while maintaining UE-specific scheduling benefits when possible.
3Reliability
If the base station increases aggregation level for PDCCH, then decoding reliability is improved, but resource consumption increases
Solution Approach 1:
The base station adjusts the aggregation level parameter dynamically based on channel conditions and CQI reliability. When channel quality is poor or CQI is unreliable, higher aggregation levels are used to improve decoding reliability. When channel conditions are good, lower aggregation levels are used to conserve control channel resources, achieving an optimal balance between reliability and resource consumption.
Data Source
Figure 1
Figure 2A~2D
Figure 3
AI summary
A first apparatus may send, to a base station, a set of channel quality indicators associated with a set of channels. The first apparatus may monitor sets of control channel elements in a search space based on the set of channel quality indicators sent to the base station. A second apparatus may receive, from a first user equipment, a set of channel quality indicators associated with a set of channels. The second apparatus may send, based on the set of channel quality indicators received from the first user equipment, control information on a physical downlink control channel associated with the first user equipment in a search space specific to the first user equipment.