PDCCH Repetition Configuration for Reliable Reduced-Capability UEs
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Solution Overview
Problem
In 5G cellular systems, reduced capability user equipment (UEs) experience unreliable communication due to affected PDCCH channel coverage, particularly for cell edge UEs, which can be addressed by enhancing the quality of service (QoS) through multiple repetitions of the physical downlink control channel (PDCCH) over monitoring occasions.
Innovation Solution
The method involves configuring user equipment (UE) and base stations to determine and transmit/receive PDCCH candidates based on RRC parameters that include CCE aggregation level (L) and repetition level (R), optimizing PDCCH monitoring and transmission through search space set configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If reduced capability UE functions are used for power and cost savings, then power consumption and device cost are reduced, but PDCCH channel coverage and communication reliability deteriorate
Solution Approach 1:
The patent changes the parameter of PDCCH transmission by introducing multiple repetitions (R times) of the same PDCCH message across different monitoring occasions. This parameter change allows reduced capability UEs to reliably receive control information despite having reduced processing capabilities, thereby maintaining communication reliability while preserving power and cost benefits of reduced capability design
Solution Approach 2:
The patent implements periodic repetition of PDCCH transmissions at defined intervals (monitoring occasions). The PDCCH is transmitted repeatedly according to a periodic pattern where the same control information is sent multiple times, allowing the UE to reliably detect and decode the control message through repeated exposure, thus resolving the reliability issue without requiring full-capability UE design
2Reliability
If multiple repetitions of PDCCH are sent over monitoring occasions, then communication reliability for cell edge UEs is improved, but system complexity and resource overhead increase
Solution Approach 1:
The patent segments the PDCCH transmission across multiple monitoring occasions rather than concentrating all transmission resources in a single occasion. By dividing the transmission into R repeated instances distributed over time, the system manages complexity through structured segmentation while achieving improved reliability through diverse reception opportunities
Solution Approach 2:
The patent employs preliminary configuration where the network pre-configures the UE with repetition parameters (R values, monitoring occasion patterns) before actual PDCCH transmission. This preliminary action allows the UE to prepare appropriate reception strategies in advance, reducing real-time processing complexity while maintaining high reliability through pre-planned repeated transmissions
3Length of stationary object
If PDCCH candidates are increased for reduced capability UEs, then channel coverage is improved, but processing load and complexity at UE increase
Solution Approach 1:
The patent uses copying by transmitting identical PDCCH content multiple times (repetition) across different monitoring occasions. Instead of increasing the number of different PDCCH candidates which would raise UE processing complexity, the system copies the same control message repeatedly, allowing reduced capability UEs to achieve reliable reception through simple repetition detection without complex processing of multiple candidate types
Data Source
AI summary
A user equipment (UE) is described. The UE includes reception circuitry configured to receive, from a base station, a first radio resource control (RRC) parameter related to a search space set configuration, wherein the first RRC parameter includes a plurality of second RRC parameters for a list of combinations, each of the second RRC parameters indicates a number of PDCCH candidates associated with a combination; and control circuitry configured to determine, based on the first RRC parameter, the number of PDCCH candidates for the search space set, and to monitor the PDCCH candidates determined by the number of PDCCH candidates.