ULP Cell Reselection for Energy-Efficient Idle Mobility
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Solution Overview
Problem
Switching between Uu cells in ultra-low power (ULP) systems limits power savings gains from ULP receivers, necessitating a method to maintain power savings without cell reselection.
Innovation Solution
Implementing ULP cell reselection without triggering Uu cell reselection by associating Uu cells with ULP cells, determining measurement offsets, and selecting ULP cells based on signal quality to maintain power savings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If switching between Uu cells is performed, then connectivity is maintained, but power savings gains from ULP receivers are limited
Solution Approach 1:
The patent segments the cell selection process into two independent parts: Uu cell selection for connectivity and ULP cell selection for power savings. The WTRU can perform ULP cell reselection without triggering Uu cell reselection, allowing these two functions to be optimized separately. This segmentation resolves the contradiction by enabling the system to maintain connectivity through Uu cells while achieving power savings through ULP cell reselection.
Solution Approach 2:
The patent introduces measurement offsets as an intermediary mechanism that allows the WTRU to compare ULP cell measurements against adjusted thresholds. The offset compensates for differences in measurement conditions between Uu and ULP cells, enabling accurate ULP cell selection without requiring full Uu cell reselection procedures. This intermediary allows the system to maintain connectivity decisions while optimizing for power savings.
2Loss of energy
If ULP cell reselection is performed without triggering Uu cell reselection, then power savings are maintained, but cell association accuracy may be affected
Solution Approach 1:
The patent applies parameter changes by introducing measurement offsets that adjust the evaluation criteria for ULP cells based on their association with different Uu cells. The offset value changes depending on whether the ULP cell is associated with the serving Uu cell or a different Uu cell. This parameter adjustment allows the system to maintain measurement precision for ULP cell selection while preserving power savings benefits.
Solution Approach 2:
The patent implements partial action by performing ULP cell measurements and selections without requiring full Uu cell reselection procedures. The WTRU performs limited measurements on neighboring ULP cells using adjusted thresholds, which is sufficient for making accurate cell selection decisions while consuming significantly less power than a full reselection process would require.
3Measurement precision
If measurement offsets are applied to neighboring ULP cells, then signal quality determination is improved, but processing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring the WTRU with information about Uu-ULP cell associations and their corresponding measurement offsets. This information is provided beforehand through network signaling, so the WTRU doesn't need to perform complex analysis during the measurement process. The offset values are prepared in advance, allowing the WTRU to simply apply them during ULP cell selection without adding significant processing complexity.
Data Source
AI summary
Systems, methods, and instrumentalities are described herein for idle mode mobility in an ultra-low power (ULP) system. Idle mode mobility in a ULP system may support energy efficient downlink signaling. An association may be identified between a Uu cell and a ULP cell. Switching between Uu cells may limit power savings gains from ULP receivers. Enabling switching between ULP cells without switching between Uu cells may help maintain the power savings gains from ULP receivers. A wireless transmit/receive unit may be configured to perform ULP cell reselection, for example, without triggering Uu cell reselection (e.g., to maintain power savings gains).