Idle-Mode Cell Selection Measurements in Unlicensed Spectrum
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Solution Overview
Problem
Facilitating efficient and reliable idle-mode measurements for cell selection in unlicensed spectrum, where downlink signals may not be transmitted in all time resources indicated for cell selection, particularly during listen-before-talk failures.
Innovation Solution
A method and apparatus for a communication device to make idle-mode cell selection measurements only in specific time resources determined from broadcast system information, refraining from measurements outside these resources, and using these measurements to select a preferred cell for camping based on signal strength and quality thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If idle-mode cell selection measurements are made continuously in all time resources, then measurement coverage is improved, but power consumption increases
Solution Approach 1:
The patent applies periodic action by configuring the communication device to perform idle-mode cell selection measurements only in specific periodic time resources (measurement windows) rather than continuously. The network configures measurement window periodicity, and the device performs measurements during these designated windows while remaining in idle mode, thereby reducing power consumption while maintaining reliable measurement coverage.
2Reliability
If idle-mode measurements are made in all time resources, then measurement reliability is improved, but measurement time increases
Solution Approach 1:
By organizing measurements into periodic windows with specific configurations (periodicity, duration, offset), the patent achieves reliable measurements within concentrated time intervals. The device performs comprehensive measurements during each measurement window, then remains inactive until the next window, reducing total measurement time while maintaining reliability through periodic sampling.
Solution Approach 2:
The network pre-configures measurement window parameters (periodicity, duration, offset relative to reference time) before the device performs measurements. This preliminary configuration allows the device to efficiently execute measurements without real-time decision-making, reducing measurement time while ensuring reliable coverage through pre-planned measurement opportunities.
3Reliability
If the communication device attempts to measure cells outside configured time resources, then measurement coverage is improved, but device complexity increases
Solution Approach 1:
The patent simplifies device complexity by establishing periodic measurement windows with fixed parameters (periodicity, duration, offset). The device only needs to activate measurements during these pre-configured windows rather than continuously monitoring all time resources, reducing measurement management complexity while maintaining coverage through regular periodic sampling.
Data Source
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AI summary
A technique for differentiating licensed-assisted-access (LAA) cells (on which a UE may not be allowed to camp) from non-LAA cells (on which a UE may camp) comprising: making at least one type of idle-mode cell selection measurement for at least one carrier in time resources determinable from broadcast system information; and refraining from making said at least one type of idle-mode cell selection measurement for said at least one carrier outside of said time resources; in alternative, the technique comprising creating a specific type of DRS for non-LAA cells which may be recognized by the UE (e. g., the DRS including an additional PSS sequence or being scrambled with a network-specific signature).