Tree-Based Resource Allocation for OFDMA CQI Feedback
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Solution Overview
Problem
In wireless access networks using multi-carrier access techniques like OFDMA, efficiently communicating channel quality indicators (CQI) is challenging due to bandwidth limitations, especially when supporting varying mobility and channel profiles, as existing methods require significant bandwidth for CQI feedback, which can limit system capacity and quality of service (QoS).
Innovation Solution
The solution involves a tree-based structure for resource allocation, allowing flexible selection of CQI feedback granularity and simultaneous support of distributed and contiguous sub-carrier allocation, where CQI is reported at a parent node to represent multiple child nodes, reducing bandwidth usage and enabling dynamic adaptation based on subscriber mobility and channel conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If CQI is reported for each individual sub-channel, then measurement precision is improved, but bandwidth consumption increases
Solution Approach 1:
The patent merges CQI reporting for multiple sub-channels by reporting a single CQI value at a parent node that represents the aggregate channel quality of multiple child nodes. This combining approach reduces the number of CQI reports from N individual sub-channels to fewer parent node reports, directly reducing bandwidth consumption while maintaining adequate measurement precision through hierarchical representation.
Solution Approach 2:
The patent implements a nested hierarchical structure where parent nodes contain multiple child nodes, and each level of the hierarchy represents aggregated sub-channel groups. This nesting allows CQI to be reported at appropriate granularity levels - individual sub-channels are nested within parent node groups, enabling selective reporting that balances precision requirements with bandwidth constraints.
2Productivity
If CQI feedback granularity is increased, then scheduling gains are improved, but feedback overhead increases
Solution Approach 1:
The patent enables dynamic adjustment of CQI feedback granularity by allowing the system to adaptively select which parent nodes report CQI based on current channel conditions and mobility patterns. When channel conditions are stable, coarser granularity (fewer parent node reports) suffices, reducing feedback overhead. When conditions change rapidly, finer granularity can be activated to maintain scheduling gains, creating a dynamic balance between the two objectives.
3Productivity
If bandwidth allocation for CQI feedback is reduced, then system capacity is improved, but CQI communication accuracy deteriorates
Solution Approach 1:
The patent segments the CQI feedback system into hierarchical levels (individual sub-channels, parent nodes, and higher-level aggregates). This segmentation allows the system to allocate feedback bandwidth efficiently by reporting CQI at the appropriate segmentation level - not every individual sub-channel needs its own report when parent node aggregation can adequately represent the channel quality, thus preserving accuracy while reducing overall feedback volume to free up bandwidth for data transmission.
Data Source
AI summary
In a wireless network, simultaneous support of distributed and contiguous sub-carrier allocation may be accomplished in the same sub-frame or time zone. Techniques are described herein that can be used to allocate distributed and/or contiguous basic (physical) resource blocks to users by specifying a codebook index and parent node. Techniques are described herein that can be used to flexibly set a number of sub-channels over which a subscriber station indicates a channel quality indicator to a base station. Sub-channels may be represented as nodes and may be grouped to include a parent node and child nodes. By specifying a code book to use and a parent node, the channel quality indicator of the parent and children nodes can be indicated.