Backhaul Link Subframe Configuration for Carrier Aggregation
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently configuring backhaul link subframes using carrier aggregation, particularly in managing HARQ timing mismatches between cells, which can lead to issues with cross carrier scheduling and interference in TDD systems.
Innovation Solution
The method involves determining subframe configurations for primary and secondary component carriers, ensuring that backhaul UL and DL subframes do not overlap, and aligning HARQ timing by transmitting ACK/NACK in specific uplink subframes of the primary component carrier corresponding to downlink data channels on secondary component carriers, thereby maintaining compatibility with legacy systems and reducing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carrier aggregation is applied to backhaul links, then system capacity and spectral efficiency are improved, but HARQ timing mismatches and scheduling complexity increase
Solution Approach 1:
The patent segments the backhaul link configuration by introducing separate subframe configuration parameters for primary and secondary component carriers. This allows independent optimization of each carrier's timing structure, resolving HARQ timing mismatches by dividing the scheduling problem into manageable segments rather than treating carrier aggregation as a monolithic complex system.
Solution Approach 2:
The patent implements dynamic subframe configuration where the base station can independently adjust uplink-downlink subframe allocations for each component carrier based on traffic conditions. This dynamic adaptation enables the system to maintain optimal HARQ timing relationships while aggregating multiple carriers, balancing capacity improvement with manageable scheduling complexity.
2Adaptability or versatility
If different subframe configurations are used for primary and secondary component carriers, then flexibility in resource allocation is improved, but timing alignment and interference management become more difficult
Solution Approach 1:
The patent applies local quality by allowing each component carrier to have its own optimized subframe configuration tailored to its specific traffic requirements and channel conditions. The primary carrier uses one configuration while secondary carriers use potentially different configurations, enabling localized optimization without causing system-wide interference through careful timing relationship management.
Solution Approach 2:
The patent introduces the base station as an intermediary that coordinates subframe configurations across multiple component carriers. The base station acts as a mediator to align timing relationships and manage potential interference between carriers with different configurations, ensuring that resource allocation flexibility does not lead to harmful interference through centralized control.
3Productivity
If cross carrier scheduling is implemented, then spectral efficiency is improved, but HARQ timing synchronization between carriers becomes more complex
Solution Approach 1:
The patent applies preliminary action by pre-configuring HARQ timing relationships between primary and secondary component carriers before cross-carrier scheduling operations. The base station establishes predetermined timing offsets and synchronization rules in advance, allowing cross-carrier scheduling to proceed efficiently without real-time timing negotiation, thus maintaining spectral efficiency while simplifying HARQ synchronization.
Data Source
AI summary
Disclosed in the present invention is a method for a base station to set a backhaul link subframe for a relay node in a wireless communication system, to which a carrier aggregation technique is applied. More particularly, the present invention comprises the steps of: determining one of the plurality of subframe settings as a first subframe setting for a main component carrier allocated to the relay node; composing subframe setting candidates for one or more subcomponent carriers allocated to the relay node, one the basis of the determined first subframe setting; and determining a second subframe setting for each of the one or more subcomponent carriers, using the composed subframe setting candidates, wherein a subframe aggregation according to the first subframe setting and subframe aggregations according to each of the subframe setting candidates do not overlap when downlink subframes and uplink subframes of the different component carriers are identical, and a downlink subframe aggregation according to the second subframe setting is included in a downlink subframe aggregation according to the first subframe setting.