PDCCH Reliability via Linked Search Space Sets
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Solution Overview
Problem
Current 5G wireless communication systems face challenges in ensuring reliable physical downlink control channel (PDCCH) transmissions, particularly in high-frequency bands where increased path loss and smaller symbol duration lead to significant coverage losses, and in scenarios with reduced receiver capabilities, such as RedCap UEs, which experience additional coverage losses.
Innovation Solution
The proposed solution involves enhancing PDCCH reliability by extending the resource element group (REG) over multiple OFDM symbols, using different demodulation reference signal (DM-RS) structures based on subcarrier spacing, and configuring search space sets with linked reception or transmission occasions to maintain identical information across multiple slots, thereby improving coverage and reducing complexity for user equipment (UE) in combining repetitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If PDCCH transmissions are performed in high-frequency bands, then capacity is increased, but path loss increases and coverage is reduced
Solution Approach 1:
The patent segments the PDCCH transmission by dividing the control information into multiple parts and transmitting them across multiple slots using multiple search space sets. Each search space set transmits a portion of the control information, allowing the UE to combine these segments to reconstruct the complete control information, thereby improving coverage while maintaining capacity in high-frequency bands
Solution Approach 2:
The patent employs periodic transmission by configuring multiple search space sets with the same periodicity, where each search space set transmits control information at regular intervals. This periodic action across multiple slots enables the UE to receive and combine multiple transmissions of the same control information, enhancing reliability and coverage without sacrificing capacity
2Reliability
If search space sets are configured with linked receptions, then PDCCH reliability is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple search space sets into a linked configuration where each search space set is associated with the same control information. The UE combines the transmissions from all linked search space sets to reconstruct the complete control information, improving reliability while the standardized merging process manages UE complexity through defined procedures
Solution Approach 2:
The patent creates a universal configuration where multiple search space sets share the same periodicity and are linked to transmit identical control information. This multi-functional approach allows a single control information to be transmitted across multiple search space sets, improving reliability while the universal configuration parameters (periodicity, linking indication) simplify UE processing by providing standardized handling procedures
Data Source
AI summary
Methods and apparatus for physical downlink control channel (PDCCH) reliability enhancements. A method includes receiving first information for a number of N>1 search space sets. For each of the N search space sets, the first information includes: an index, wherein search space sets are indexed in an ascending order of respective indexes, a periodicity, wherein the periodicity is same for all of the N search space sets, and an indication that the N search space sets are linked for receptions of PDCCHs, wherein the PDCCHs provide identical information. The method further includes determining a number of N PDCCH reception occasions in M≥1 slots within a period according to the periodicity. A n-th PDCCH reception occasion from the NPDCCH reception occasions is according to a n-th search space set from the N search space sets. The method further includes receiving N PDCCHs in the N PDCCH reception occasions.