User Equipment Cell Discovery During Out of Service
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Solution Overview
Problem
User equipment (UE) in wireless telecommunications systems face challenges in maintaining network connectivity when moving out of a service area, leading to potential loss of coverage due to temporary or long-term disruptions, such as physical movement, interference, or technical issues, necessitating efficient methods to discover and re-establish a suitable serving cell before connection loss.
Innovation Solution
The UE is configured with a processor to periodically or shortly before losing connection, search for a suitable cell among proximate cells by checking for coverage based on timers and radio access technologies, prioritizing re-checks on the last used frequency to quickly re-establish communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE waits until the timer expires before searching for a new cell, then the power consumption is reduced, but the connection is lost
Solution Approach 1:
The UE performs cell search and evaluation actions before the timer actually expires by checking for suitable cells at predetermined intervals during the out-of-service period. This preliminary action ensures that if a suitable cell is found, the connection can be re-established quickly without waiting for timer expiration, thus maintaining connection continuity while reducing reconnection time.
2Reliability
If the UE searches for cells frequently, then the connection recovery is faster, but the power consumption increases
Solution Approach 1:
The UE performs cell searches at predetermined periodic intervals during the out-of-service timer period rather than continuously or too frequently. This periodic action allows the system to balance between recovering connection quickly (by searching regularly) and conserving power (by not searching continuously), achieving optimal connection recovery speed with acceptable power consumption.
3Reliability
If the UE checks all frequencies, then the cell discovery is thorough, but the time to find a cell increases
Solution Approach 1:
The UE prioritizes checking the last used frequency first as a preliminary action before checking other frequencies. Since the previous serving cell's frequency is most likely to still be available or have a suitable neighbor cell, this preliminary check on the last used frequency can quickly restore connectivity without needing to exhaustively search all frequencies, thus reducing cell search time while maintaining discovery completeness.
Data Source
Figure 1~2
Figure 3A
Figure 3B
AI summary
A user equipment is provided. The user equipment comprises a processor that, when the UE goes out of service area of a first cell, is configured to search for a suitable cell before the UE loses a connection to a network by checking for a suitable cell among cells proximate to the first cell, based on a timer before the UE loses the connection to the network.