PDCCH Repetition for Reduced Capability UE Coverage
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Solution Overview
Problem
In 5G wireless networks, reduced capability user equipment (UE) experiences unreliable communication due to affected PDCCH channel coverage, particularly at cell edges, leading to poor quality of service (QoS) due to reduced functions for power and cost savings.
Innovation Solution
Implementing PDCCH candidate repetition over multiple monitoring occasions, where the base station transmits physical downlink control channel (PDCCH) with multiple repetitions, and user equipment (UE) monitors PDCCH candidates based on received RRC parameters indicating the number of monitoring occasions, to enhance coverage and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If reduced capability UE functions are implemented 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 PDCCH transmission is segmented into multiple repetitions across different monitoring occasions. Each repetition carries the same control information, allowing the UE to combine multiple segments to achieve the required reliability while maintaining reduced device complexity
Solution Approach 2:
The base station performs preliminary action by transmitting multiple PDCCH repetitions in advance before the UE needs to decode the control information. This ensures that even with reduced capability UE, the control information is delivered reliably through cumulative signal combining
2Ease of manufacture
If reduced capability UE functions are implemented for cost savings, then device cost is reduced, but PDCCH channel coverage deteriorates
Solution Approach 1:
The control channel transmission is divided into multiple temporal segments (repetitions) that can be combined at the receiver. This allows reduced capability UEs to achieve extended coverage through signal combining without requiring more complex hardware
Solution Approach 2:
Multiple PDCCH repetitions are merged/combined at the UE receiver through soft combining or maximal ratio combining. This merging process extends the effective coverage range by accumulating signal energy across multiple transmissions
3Reliability
If multiple PDCCH repetitions are transmitted over monitoring occasions, then PDCCH coverage and reliability are improved, but signaling overhead and processing complexity increase
Solution Approach 1:
The base station configures the UE with RRC parameters indicating the number of monitoring occasions and PDCCH repetitions in advance. This preliminary configuration allows the UE to prepare its monitoring strategy and reduces real-time processing complexity
Solution Approach 2:
The system uses RRC signaling to provide feedback/configuration about the PDCCH repetition structure. This allows the UE to adapt its monitoring behavior to the configured repetition pattern, optimizing processing efficiency while maintaining reliability
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 one or more second RRC parameters, indicating a number of monitoring occasions R associated to each DCI; and monitoring circuity configured to monitor, based on the first RRC parameter, a set of PDCCH candidates for the search space set.