PDCCH Decoding Search Space Ordering for 5G
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Solution Overview
Problem
In 5G wireless communication systems, the computationally intensive process of blind decoding multiple search space sets for Physical Downlink Control Channel (PDCCH) decoding consumes significant power and lacks an optimal decoding logic, especially due to the absence of defined order for PDCCH decoding across multiple search space sets.
Innovation Solution
The method involves configuring multiple search space sets within a channel bandwidth, ordering them based on the number of PDCCH candidates per aggregation level, and selecting the appropriate search space set for transmitting Downlink Control Information (DCI) based on a Channel Quality Indicator (CQI) value received from the User Equipment (UE).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If blind decoding of multiple search space sets is performed for PDCCH decoding, then the reliability of control information reception is improved, but the power consumption and decoding complexity increase significantly
Solution Approach 1:
The base station performs preliminary ordering of search space sets based on aggregation level configurations before transmission. The UE receives this ordering information and follows it during decoding, avoiding the need to independently evaluate multiple search space sets in arbitrary orders. This preliminary arrangement significantly reduces the number of decoding attempts required while ensuring reliable control information reception.
2Adaptability or versatility
If multiple search space sets with different aggregation levels are configured, then the adaptability to varying channel conditions is improved, but the device complexity and decoding overhead increase
Solution Approach 1:
The search space sets are segmented by aggregation levels (AL1, AL2, AL4, AL8, etc.), with each set dedicated to specific channel conditions. The base station configures and orders these segmented sets according to channel quality requirements. The UE only needs to decode search space sets appropriate for the current channel conditions, reducing overall decoding complexity while maintaining adaptability.
Solution Approach 2:
The system changes the aggregation level parameter based on channel conditions. Higher aggregation levels provide more robust decoding for poor channel conditions, while lower aggregation levels are sufficient for good channel conditions. The ordered search space set configuration enables the UE to select appropriate aggregation levels dynamically, balancing adaptability with reduced decoding complexity.
3Reliability
If the number of PDCCH candidates per aggregation level is increased, then the probability of successful decoding is improved, but the processing time and energy consumption increase
Solution Approach 1:
The base station performs preliminary ordering of search space sets by aggregation level before transmission. The UE receives this ordering and follows it during decoding, starting from the most appropriate aggregation level for current channel conditions. This eliminates the need for the UE to attempt decoding in multiple aggregation levels sequentially, significantly reducing processing time while maintaining high decoding success probability through the pre-optimized ordering.
Data Source
AI summary
Disclosed herein is method for optimizing Physical Downlink Control Channel (PDCCH) decoding by a base station in a wireless communication system. In an embodiment, a plurality of search spaces is configured within bandwidth of channel used for sending data packets to a user equipment (UE). Further, plurality of search spaces is ordered in a specified order, such that first end of specified order comprises search space set having higher number of candidates with lower aggregation levels and second end comprises search space set having higher number of candidates with higher aggregation levels. A channel quality indicator (CQI) value is received from UE and based on CQI value, an order for selecting one of plurality of search space set for sending downlink control information (DCI) to the UE is determined. An available search space set among determined one of plurality of search space set is selected for transmitting the DCI to the UE.