Unlicensed Carrier Aggregation Timing Alignment to Avoid IDC
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Solution Overview
Problem
In-device coexistence (IDC) problems arise when user equipment (UE) communicates using multiple unlicensed bands concurrently, leading to self-interference due to timing misalignment between master and secondary nodes in dual connectivity operations.
Innovation Solution
A master node sends timing information, such as Tstart and GMFQDN, to a secondary node to align slot and symbol boundaries, ensuring synchronized communication across different unlicensed bands, thereby preventing IDC issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple unlicensed bands are used concurrently for dual connectivity operations, then spectrum utilization and data throughput are improved, but self-interference and in-device coexistence problems occur due to timing misalignment between master and secondary nodes
Solution Approach 1:
The patent applies parameter changes by adjusting timing parameters (Tstart, GMFQDN) of the secondary node to align with the master node's timing structure. This ensures that slot and symbol boundaries are synchronized between master and secondary nodes, preventing self-interference while maintaining concurrent operation on multiple unlicensed bands. The timing alignment parameter adjustment resolves the contradiction by modifying the temporal parameters of signal transmission.
2Reliability
If timing alignment is implemented between master and secondary nodes, then in-device coexistence problems are eliminated, but system complexity increases due to additional timing information exchange and synchronization mechanisms
Solution Approach 1:
The patent implements preliminary action by pre-configuring timing information (Tstart and GMFQDN) in the secondary node addition request message before actual data transmission begins. This advance timing synchronization setup ensures that when the secondary node starts operating, it is already aligned with the master node's timing structure, preventing IDC issues from the outset. The timing alignment is established in advance rather than dynamically adjusted during operation.
Solution Approach 2:
The patent uses timing information messages (containing Tstart and GMFQDN parameters) as an intermediary mechanism to transfer synchronization data from the master node to the secondary node. This intermediary timing information serves as a bridge that coordinates the timing structures of both nodes without requiring complex direct synchronization protocols, thereby reducing system complexity while maintaining reliability.
3Object-affected harmful factors
If slot-boundary and symbol boundary alignment is achieved between master and secondary nodes, then self-interference is prevented, but transmission latency increases due to timing coordination requirements
Solution Approach 1:
The patent minimizes latency by optimizing the timing parameters (Tstart offset and GMFQDN) to achieve alignment with the smallest possible time adjustment. By carefully selecting the Tstart value, the secondary node can align its slot and symbol boundaries with the master node while introducing minimal delay. This parameter optimization ensures that timing alignment is achieved with the least possible impact on transmission latency.
Data Source
AI summary
A master node (MN) communicating with a UE using resources of a first band of unlicensed spectrum sends an addition request to a selected secondary node, to request resources for supporting the UE in a second band of unlicensed spectrum. The addition request includes timing information including one or more of: i) information indicating a start time for the MN time division duplexing (TDD) timing structure with respect to the UE, or ii) information indicating a reference clock being used by the MN. The secondary node uses the received timing information from the MN to perform timing alignment at the secondary node. The adjusted timing alignment of the secondary node allows the UE to achieve slot-boundary and/or symbol boundary alignment with regard to MN communications using the first unlicensed spectrum and SN communications using the second unlicensed spectrum. Due to the achieved synchronization, an in-device coexistence (IDC) problem is avoided.