NB-IoT UE Measurement Procedure Selection for RRC Re-Establishment
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Solution Overview
Problem
NB-IoT UE faces challenges in consistently and reliably performing neighbor cell measurements due to inconsistent measurement behavior, especially during DRX cycles and when switching between different carrier frequencies, which affects timely cell change upon radio link failure.
Innovation Solution
The UE determines the relation between the serving cell's carrier frequency and a potential new cell's carrier frequency and selects an appropriate measurement procedure (Procedure A for intra-frequency or Procedure B for inter-frequency) to perform measurements, ensuring guaranteed measurement occasions and reference signals are available.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE performs neighbor cell measurements during DRX cycles and carrier frequency switching, then measurement coverage is improved, but measurement consistency and reliability deteriorate due to inconsistent measurement behavior
Solution Approach 1:
The patent implements dynamic measurement procedure selection based on the frequency relationship between serving cell and neighbor cells. When frequencies match, Procedure A is used; when they differ, Procedure B is used. This dynamic adaptation resolves the contradiction by adjusting measurement behavior to operating conditions, ensuring reliability without requiring a single complex procedure for all scenarios.
Solution Approach 2:
The patent changes measurement parameters (procedure type) based on the frequency relation parameter between serving and neighbor cells. This parameter-based differentiation allows the system to optimize measurement reliability for each frequency scenario, avoiding the inconsistency that would occur with a uniform measurement approach across different frequency conditions.
2Adaptability or versatility
If the UE performs inter-frequency measurements, then cell selection capability is improved, but power consumption increases due to additional frequency switching
Solution Approach 1:
The patent segments the measurement process into two distinct procedures based on frequency relationship. Procedure A handles intra-frequency measurements with lower power consumption, while Procedure B handles inter-frequency measurements when necessary for cell selection. This segmentation allows the UE to minimize power consumption by using the simpler Procedure A whenever possible, while retaining the capability to perform inter-frequency measurements when adaptability is required.
Solution Approach 2:
The patent dynamically selects between measurement procedures based on whether inter-frequency measurement is actually needed for cell selection. This dynamic approach ensures that the UE only incurs the additional power cost of frequency switching when necessary, rather than continuously performing inter-frequency measurements, thus balancing adaptability with power efficiency.
3Device complexity
If the UE uses a single measurement procedure for all frequencies, then device complexity is reduced, but measurement precision deteriorates due to inability to account for frequency-specific conditions
Solution Approach 1:
The patent applies local quality by tailoring the measurement procedure to the specific frequency relationship between serving and neighbor cells. Procedure A is optimized for intra-frequency conditions, while Procedure B is optimized for inter-frequency conditions. This local optimization ensures measurement precision is maximized for each frequency scenario without requiring the UE to implement a single overly complex procedure that attempts to handle all cases uniformly.
Data Source
AI summary
Upon detecting a triggering condition (e.g., a transition between RRC states, a radio link problem (RLP), etc.), a UE determines a first carrier frequency (F1) of serving cell (Cell1) and a second carrier frequency (F2) of a second cell (Cell2), are different, and selects a measurement procedures to measure on Cell2. The UE is configured with F2 by the network node for performing the RRC connection re-establishment procedure, e.g., when RLP is detected. The UE measures on Cell2 based on a measurement procedure in which the measurement occasions are limited to specific occasions, where at least a certain number of reference signals are guaranteed. The measurement procedure used for performing measurement on Cell2 may further depend on the measurement triggering condition. The UE may further determine the time instance when the UE initiates measurements on Cell2 based on the triggering condition.