CSI-RS Resource Element Allocation for Interference Estimation
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Solution Overview
Problem
Current CSI-RS density in LTE systems is insufficient for accurate interference covariance estimation, leading to errors in CQI and rank feedback, which affects transmission scheme selection and results in throughput loss, especially in heterogeneous networks with challenging interference characteristics.
Innovation Solution
Increasing the density of resource elements in a physical resource block (PRB) for CSI-RS while ensuring backwards compatibility with legacy mobile terminals by positioning additional CSI-RS elements to be interpreted as muted by older systems, thereby avoiding interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the density of resource elements for CSI-RS is increased to improve channel state information and interference estimation accuracy, then measurement precision improves, but device complexity increases due to additional resource element definitions and backwards compatibility requirements
Solution Approach 1:
The patent applies local quality by differentiating resource element allocation for different terminal types. Legacy terminals interpret certain resource elements as muted (lower quality requirement), while advanced terminals utilize the same resource elements for CSI-RS (higher quality requirement). This allows localized optimization where advanced terminals receive enhanced channel state information without imposing complexity on legacy terminals.
Solution Approach 2:
The patent resolves the contradiction by adding a dimensional layer of terminal type differentiation. Instead of uniformly increasing CSI-RS density across all terminals, it creates a multi-dimensional resource allocation where the same physical resource elements serve different purposes for different terminal types, effectively increasing density for advanced terminals while maintaining compatibility with legacy ones.
2Object-affected harmful factors
If additional CSI-RS resource elements are positioned to overlap with muted resource elements for legacy terminals, then interference is avoided for legacy systems, but the quantity of resource elements required increases to achieve sufficient CSI-RS density
Solution Approach 1:
The patent converts the harmful factor of muted resource elements into a beneficial opportunity. By positioning CSI-RS in resource elements that legacy terminals interpret as muted, the patent ensures that legacy terminals experience no interference from these elements, while advanced terminals can fully utilize them for CSI-RS transmission. This transforms potential interference zones into dedicated CSI-RS resources.
3Reliability
If CSI-RS density is increased to reduce errors in CQI and rank feedback, then reliability improves, but loss of information decreases only marginally due to overhead constraints
Solution Approach 1:
The patent applies universality by making resource elements serve multiple functions simultaneously. The same resource elements are used for CSI-RS transmission to advanced terminals while being interpreted as muted by legacy terminals. This multi-functional usage increases effective CSI-RS density without proportionally increasing overall resource overhead, as the muted resource elements would otherwise be unavailable for data transmission to legacy terminals.
Data Source
AI summary
Methods, apparatus and computer program products define additional resource elements of a physical resource block (PRB) to be allocated for the provision of channel state information reference signals in a manner that does not create issues relating to backwards compatibility for legacy mobile terminals. A method may include receiving a definition of a plurality of resource elements of a PRB to be allocated for provision of channel state information reference signals. At least some of the plurality of resource elements of the PRB that are allocated for the provision of channel state information reference signals correspond in position to resource elements of the PRB that are interpreted by a different type of mobile terminal to be muted. The method also causes, channel state information reference signals to be received via the plurality of resource elements of the PRB that are allocated for the provision of channel state information reference signals.