PDCCH Monitoring on SCell for PCell Scheduling in 5G NR
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Solution Overview
Problem
In 5G NR networks, efficient coexistence with 4G systems during dynamic spectrum sharing is challenging due to limitations in PDCCH design, particularly in avoiding interference with LTE channels, which affects the scheduling of PDSCH and PUSCH transmissions.
Innovation Solution
User equipment (UE) and generation node B (gNB) configurations that allow monitoring and scheduling of PDCCH candidates and non-overlapped CCEs on both primary and secondary cells, optimizing the number of monitored resources to enhance PDCCH detection capability and avoid rate matching, thereby supporting dynamic spectrum sharing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If PDCCH of SCell schedules PDSCH and/or PUSCH transmissions of PCell, then scheduling flexibility and spectrum sharing efficiency are improved, but PDCCH detection complexity and interference with LTE channels increase
Solution Approach 1:
The patent segments the PDCCH monitoring task by separating control information into different search spaces on different cells. UE monitors PDCCH candidates in search spaces of both PCell and SCell, with specific rules for handling overlapping CCEs between cells, thereby managing complexity through structured division of monitoring responsibilities
Solution Approach 2:
The patent introduces search space sets as intermediary structures that mediate between the scheduling cell and monitored cell. These search spaces define specific resource regions where PDCCH candidates are expected, acting as intermediaries to organize the complex task of monitoring across multiple cells with potential overlaps
2Productivity
If UE monitors PDCCH candidates on both PCell and SCell, then scheduling capability is improved, but number of monitored resources and detection burden increase
Solution Approach 1:
The patent applies partial action by requiring UE to monitor only a subset of PDCCH candidates in each search space, with the number of candidates limited by configured parameters. This partial monitoring approach balances scheduling capability with detection burden, avoiding the need to monitor all possible control signals
Solution Approach 2:
The patent uses parameter changes through configurable limits on the number of PDCCH candidates and non-overlapped CCEs. These parameters can be adjusted based on network conditions and UE capability, allowing dynamic optimization of the balance between scheduling capability and detection complexity
3Reliability
If NR transmission avoids resource used by LTE PDCCH, then LTE channel estimation performance is improved, but NR PDCCH transmission options are reduced
Solution Approach 1:
The patent resolves the resource conflict by moving to another dimension - using different cells for different functions. PCell handles LTE operations while SCell handles NR operations, with cross-carrier scheduling allowing SCell PDCCH to schedule PCell PDSCH. This dimensional separation allows both LTE and NR to coexist without direct resource conflicts
Solution Approach 2:
The patent makes the SCell PDCCH multi-functional by enabling it to schedule both SCell own transmissions and PCell transmissions. This universal scheduling capability provides additional transmission options for NR while avoiding interference with LTE PDCCH resources on the PCell
Data Source
AI summary
A user equipment (UE) configured for operating in a fifth-generation (5G) new radio (NR) network may monitor search space sets for a number of physical downlink control channel (PDCCH) candidates within a number of non-overlapped control-channel elements (CCEs) for a primary cell (PCell). The number of PDCCH candidates and the number of non-overlapped CCEs may include PDCCH candidates and non-overlapped CCEs on a scheduling secondary cell (SCell). The scheduling SCell may be an SCell that schedules a transmission on the PCell. The UE may decode one or more of the PDCCH candidates on the scheduling SCell for a downlink control information (DCI) format which may schedule a physical downlink shared channel (PDSCH) transmission and/or a physical uplink shared channel (PUSCH) transmission of the PCell.