Scrambling Code Filtering for UE Power Savings in Mobile Networks
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Solution Overview
Problem
User equipment (UE) in wireless communication systems faces power consumption issues when trying to maintain an up-to-date neighbor cell list while in idle mode, as it must decode system information from cells not in its locally stored list, leading to potential improper handovers and reselections due to outdated information.
Innovation Solution
The UE determines if a received signal is scrambled by a code not in its locally stored list and applies rules to decide whether to decode broadcast system information, using the scrambling code as a filter to conserve power and avoid unnecessary decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE decodes system information from all detected cells to maintain an up-to-date neighbor cell list, then the accuracy of handover and reselection is improved, but the power consumption increases significantly
Solution Approach 1:
The patent extracts only the necessary information (scrambling code) from the cell signal without performing full system information decoding. By taking out just the scrambling code identification step and stopping there, the UE avoids the power-intensive full decoding process while still gathering enough data to determine whether the cell is a valid neighbor, thus reducing power consumption while maintaining handover accuracy.
Solution Approach 2:
The patent performs preliminary identification of the scrambling code before committing to full system information decoding. This preliminary action allows the UE to filter out cells that are unlikely to be valid neighbors early in the process, avoiding unnecessary full decodings and thereby reducing overall power consumption while ensuring that potential handover targets are identified accurately.
2Loss of information
If the UE stores and reports all detected neighbor cells including those not in the locally stored NCL, then the neighbor cell list accuracy is improved, but the complexity of measurement and reporting increases
Solution Approach 1:
The patent uses the scrambling code as an intermediary identifier to simplify the neighbor cell detection process. Instead of requiring full system information decoding to identify cells, the scrambling code serves as a mediator that provides sufficient information to determine cell identity and validity. This reduces measurement complexity while maintaining information completeness about detected neighbors.
3Speed
If the UE continuously monitors and updates the neighbor cell list while in idle mode, then the handover responsiveness is improved, but the battery life is reduced
Solution Approach 1:
The patent extracts only the essential scrambling code information from neighbor cells during idle mode monitoring, avoiding full system information decoding. This extraction approach maintains the ability to quickly identify potential handover targets (preserving responsiveness) while dramatically reducing the power consumption associated with continuous monitoring, thereby extending battery life.
Solution Approach 2:
The patent performs partial monitoring by identifying scrambling codes without completing full system information decoding for all detected cells. This partial action is sufficient to maintain handover responsiveness while avoiding the excessive power consumption of complete decoding, achieving a balance between speed and battery life.
Data Source
AI summary
A UE in the idle or semi-idle state determines that a wirelessly received signal is scrambled by a scrambling code which is not within a locally stored list of scrambling codes received from its serving network node, and applies a rule to determine from the scrambling code whether to decode broadcast system information that is transmitted by an access node using the scrambling code. In one embodiment such a rule is that if the scrambling code is not within the list, do not decode the broadcast system information again if the scrambling code is locally stored from a previous instance of decoding the system information. Another rule embodiment is if the scrambling code is not within the list, do not attempt to decode the system information unless a measured signal strength for the wirelessly received signal is higher than a threshold, which may be absolute or dependent on strength of a signal received from the serving network node.