Reference Cell Groups for UE Synchronization Without Per-Cell SSBs
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Solution Overview
Problem
The challenge in wireless networks is how UEs should utilize reference signals (RS) for synchronization and communication with cells that do not transmit SSBs, as well as how the network controls which cells serve as reference cells and ensures continuous synchronization for UEs.
Innovation Solution
The solution involves configuring a Reference Cell Group (RCG) where one cell acts as a reference cell (RC) and others as auxiliary cells, with the RC transmitting a first RS that the UE uses for synchronization and operations in the auxiliary cells, and includes rules and criteria for determining and managing this configuration based on UE capabilities and network control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all cells transmit reference signals (SSBs) for synchronization, then UE synchronization and communication reliability is improved, but signaling overhead and network interference increase
Solution Approach 1:
The patent segments the set of serving cells into reference cell groups (RCGs), where each group has a designated reference cell that transmits SSBs while other cells in the group do not. This segmentation allows the network to maintain synchronization reliability through reference cells while reducing overall signaling overhead by having only a subset of cells transmit reference signals.
Solution Approach 2:
The patent introduces an intermediary mechanism where the reference cell serves as a mediator for synchronization. The reference cell transmits reference signals that are used by UEs to synchronize with multiple serving cells, including cells that do not transmit their own reference signals. This intermediary approach eliminates the need for every cell to transmit reference signals while maintaining synchronization reliability.
2Reliability
If all cells transmit reference signals, then UE synchronization is ensured, but network capacity for data transmission is reduced
Solution Approach 1:
By segmenting cells into RCGs with designated reference cells, the patent enables more network resources to be allocated to data transmission. Only the reference cells in each group transmit reference signals, while other cells can focus on data transmission, thereby increasing overall network capacity while maintaining synchronization through the reference cell mechanism.
3Productivity
If cells without SSBs are supported, then network flexibility and capacity are improved, but UE complexity for determining reference cells increases
Solution Approach 1:
The patent applies preliminary action by having the network configure RCGs and designate reference cells before data transmission begins. The UE receives configuration information about which cells are reference cells and which are auxiliary cells, eliminating the need for the UE to independently determine reference cells. This reduces UE complexity while enabling cells without SSBs to operate efficiently.
Solution Approach 2:
The patent implements feedback mechanisms where the network provides configuration information to the UE about RCG structure, and the UE reports its capabilities and status back to the network. This feedback loop enables the network to optimize RCG configuration based on UE capabilities, reducing complexity at the UE level while maintaining network flexibility.
Data Source
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AI summary
Embodiments include methods for a user equipment (UE) configured to communicate with a radio access network (RAN) via a plurality of serving cells. Such methods include determining a reference cell group (RCG) from the plurality of serving cells. The RCG includes one of the serving cells as a reference cell (RC) and one or more other of the serving cells as auxiliary cells. Such methods include receiving a first reference signal (RS) from the RC. The first RS is not received by the UE from the one or more auxiliary cells. Such methods include performing one or more operations in the one or more auxiliary cells based on the first RS received from the RC.Other embodiments include complementary methods for a RAN node, as well as UEs and RAN nodes configured to perform such methods.