Flexible Spectrum Cell Search via Carrier Segmentation
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Solution Overview
Problem
In multi-carrier cellular communication systems, maintaining compatibility between Rel-8 and Rel-9 systems is challenging, particularly during UE cell search and selection, as current methods can be resource-intensive and prone to confusion due to inter-cell and co-channel interference, especially with flexible spectrum use (FSU) allowing multiple operators to share the same carrier spectrum.
Innovation Solution
A method to determine a multi-carrier structure based on synchronization and broadcast channels, allowing UE to select an intended carrier for initial access or cell reselection by using predefined relations between carriers, explicit or implicit coordination, and a redirecting synchronization pointer (RSP) to differentiate between Rel-8 and Rel-9 carriers, reducing protocol overhead and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If UE performs cell search and selection in multi-carrier system with flexible spectrum use, then system capacity and spectrum efficiency are improved, but cell search complexity and interference confusion increase
Solution Approach 1:
The patent segments the multi-carrier system into individual carriers, each with its own synchronization channel and broadcast channel. The UE searches and selects carriers individually rather than treating the entire spectrum as a single unit, reducing the complexity of cell search while maintaining spectrum efficiency through multi-carrier operation.
Solution Approach 2:
The patent introduces a redirecting synchronization pointer (RSP) as an intermediary mechanism that helps UE distinguish between different carriers and understand the multi-carrier structure. The RSP acts as a mediator that simplifies the UE's perception of the complex multi-carrier environment, reducing search complexity while maintaining system capacity.
2Adaptability or versatility
If Rel-8 and Rel-9 carriers coexist in the same cell, then system compatibility is improved, but carrier differentiation and interference management become more difficult
Solution Approach 1:
The patent applies local quality by making each carrier have distinct local characteristics through carrier-specific synchronization channels and broadcast channels. Even though Rel-8 and Rel-9 carriers coexist in the same cell, each carrier maintains its own unique identification and synchronization properties, making differentiation easier for the UE while maintaining backward compatibility.
Solution Approach 2:
The patent uses different synchronization channel structures and broadcast channel contents as distinguishing markers (analogous to color changes) between Rel-8 and Rel-9 carriers. The redirecting synchronization pointer explicitly indicates the carrier type, allowing UE to easily differentiate between legacy and advanced carriers while both operate in the same spectrum.
3Productivity
If multiple operators share the same carrier spectrum with flexible spectrum use, then spectrum utilization is improved, but inter-cell interference and co-channel interference increase
Solution Approach 1:
The patent segments the spectrum into individual carriers with dedicated synchronization and broadcast channels for each carrier. This segmentation allows multiple operators to share the overall spectrum while maintaining distinct carrier boundaries, reducing inter-cell and co-channel interference through proper carrier differentiation and synchronization.
Data Source
Figure 1A~1C
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AI summary
Structure of a multi-carrier flexible spectrum wireless cell is determined from received synchronization or broadcast channels of detected individual carriers. The determined structure is used to select an intended carrier for initial access or cell reselection to the flexible spectrum wireless cell. The structure may have carriers compatible with an earlier version (LTE/Release 8) of a communication standard and with a later version (LTE-A/Release 9). The received synchronization channels can inform of: relative positions of the individual carriers in a spectrum band of the multi-carrier structure; relative timing alignments of the received synchronization channels; contents of the received synchronization channels; and/or layer 1 cell-carrier identifiers. The synchronization channels may have a different structure as between the earlier and later versions, and the different structure is used to select the carrier that is compatible with the user equipment making the selection.