Cell Selection Offsets for REDCAP Uplink Coverage Limits
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Solution Overview
Problem
Reduced capability terminal devices (REDCAP UEs) face communication failures due to insufficient uplink transmit power, despite being within the downlink coverage area, as they cannot perform uplink enhancement, leading to inconsistent cell selection and reselection criteria with other devices.
Innovation Solution
A cell selection method that differentiates parameters based on uplink capability, using specific offsets for Srxlev and Squal, ensuring appropriate cell selection and reselection for devices capable and incapable of uplink enhancement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a unified cell selection criterion is used for all terminal devices, then the cell selection process is simple and uniform, but reduced capability terminal devices with low uplink transmit power fail to establish normal wireless communication
Solution Approach 1:
The patent applies local quality by differentiating cell selection criteria based on terminal device capabilities. Specifically, devices with uplink enhancement capability use one set of selection parameters (Q_rxlevmin, Q_qualmin), while devices without this capability use adjusted parameters (Q_rxlevmin+N, Q_qualmin+M). This localized adaptation ensures each device type can reliably communicate with selected cells.
Solution Approach 2:
The patent changes the cell selection parameters based on uplink capability. For terminals without uplink enhancement, minimum receive level Q_rxlevmin and minimum receive quality Q_qualmin are increased by offsets N and M respectively. This parameter adjustment compensates for insufficient uplink transmit power, ensuring reliable communication while maintaining a structured selection process.
2Adaptability or versatility
If reduced capability terminal devices select cells using standard criteria, then they can access cells within downlink coverage area, but they cannot perform wireless communication due to insufficient uplink transmit power
Solution Approach 1:
The patent applies preliminary anti-action by pre-adjusting cell selection criteria to prevent communication failure. Before cell selection, terminals without uplink enhancement capability apply offsets N and M to Q_rxlevmin and Q_qualmin respectively. This preliminary adjustment ensures that selected cells have sufficient uplink coverage, preventing the harmful effect of communication failure before it occurs.
3Reliability
If uplink enhancement is mandatory for all terminals to ensure communication reliability, then communication reliability improves, but device complexity and system requirements increase
Solution Approach 1:
The patent segments the terminal device population into two groups based on uplink enhancement capability. Group 1 (with enhancement) uses standard cell selection criteria, while Group 2 (without enhancement) uses adjusted criteria with offsets. This segmentation allows the system to maintain communication reliability for all devices without requiring uplink enhancement to be mandatory, thus avoiding increased device complexity.
Data Source
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AI summary
This application provides a cell selection method and apparatus, to resolve abnormal wireless communication between a terminal device and a selected cell. The method includes: A terminal device may obtain a first offset of at least one first to-be-selected cell. The first offset is used to determine a cell selection parameter of the at least one first to-be-selected cell. The cell selection parameter includes a cell selection receive level value Srxlev and/or a cell selection receive quality value Squal. Next, the terminal device may determine, based on uplink capability information of the terminal device, the cell selection parameter of the at least one first to-be-selected cell by using the first offset. The uplink capability information indicates whether the terminal device can perform uplink enhancement. Then, the terminal device may determine a first cell based on the cell selection parameter. The first cell is one of the at least one first to-be-selected cell.