RedCap NR Downlink Repetition for Coverage Loss Recovery
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Solution Overview
Problem
The current NR system is not designed to meet the requirements of Redcap UE, which includes low cost, low complexity, and certain coverage enhancement, leading to coverage loss due to reduced receiving antennas.
Innovation Solution
Implementing a downlink transmission method that includes determining parameters for the number of repeated transmissions of physical downlink control and shared channels, along with time domain positions, to enhance coverage and optimize communication performance for Redcap UE.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the number of receiving antennas of Redcap UE is reduced to meet low cost and low complexity requirements, then device cost and complexity are reduced, but coverage is degraded and communication performance is affected
Solution Approach 1:
The network device performs repeated transmissions of PDCCH and PDSCH channels before the terminal needs to decode them successfully. By transmitting multiple copies of the control and data channels in advance, the system ensures that even with reduced antenna diversity, the terminal can accumulate sufficient signal energy through combining multiple receptions, thereby maintaining coverage without increasing antenna count.
Solution Approach 2:
The patent implements periodic repeated transmissions of downlink channels at specific time intervals. The network device transmits PDCCH and PDSCH channels multiple times with predetermined time spacing, allowing the terminal to perform time-domain combining. This periodic repetition compensates for the reduced spatial diversity from fewer antennas by providing multiple temporal opportunities for successful reception.
2Reliability
If repeated transmissions of PDCCH and PDSCH channels are increased to enhance coverage, then coverage is improved, but system complexity and resource overhead increase
Solution Approach 1:
The patent introduces specific parameters to control the repeated transmission process: a first parameter indicating the number of repeated transmissions for PDCCH, a second parameter for PDSCH repetitions, and a third parameter for time domain position. By parameterizing the repetition count and timing, the system can flexibly adjust coverage enhancement levels based on channel conditions and terminal capabilities, avoiding excessive complexity while achieving the required coverage.
Solution Approach 2:
The downlink transmission is segmented into distinct controllable components: PDCCH repeated transmissions, PDSCH repeated transmissions, and time domain positioning. Each component can be independently configured and optimized. This segmentation allows the network to apply different repetition strategies to control channels versus data channels, reducing overall system complexity compared to a monolithic repeated transmission approach.
Data Source
AI summary
A terminal in a 5G new radio (NR) network that meets the requirements of mid-range Internet of Things (IoT) devices is referred to as a reduced capability user equipment (UE) or simply called Redcap UE. A downlink transmission method for use with a Redcap UE includes: determining a first parameter configured to indicate the number of repeated transmissions of a physical downlink control channel of a first type of terminal; and performing downlink transmissions based on the first parameter.