LTE-A Reference Signal Mapping for Interference Estimation
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Solution Overview
Problem
LTE-A systems require higher accuracy in interference estimation, which is not adequately addressed by existing configurations of downlink channel quality measurement reference signals.
Innovation Solution
A radio base station apparatus generates and maps channel quality measurement reference signals (CSI-RSs) to two adjacent symbols or punctures a subcarrier in a particular symbol to enhance interference estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If channel quality measurement reference signals are mapped to positions far apart in frequency or time domains, then coverage area is improved, but interference estimation accuracy deteriorates
Solution Approach 1:
The reference signal is segmented into two parts: CSI-RS for channel quality measurement and CRS for interference estimation. These are mapped to different resource positions, allowing the system to achieve both wide coverage through CRS and accurate interference estimation through dedicated CSI-RS resources.
Solution Approach 2:
A puncture pattern is introduced as an intermediary mechanism. By puncturing specific resource elements where CRS is mapped, the system ensures that CSI-RS and CRS do not interfere with each other, while maintaining the ability to estimate interference accurately using the punctured CRS resources.
2Measurement precision
If channel quality measurement reference signals are mapped to positions close together, then interference estimation accuracy is improved, but coverage area deteriorates
Solution Approach 1:
The system segments interference estimation functionality from channel quality measurement by using separate reference signals (CRS and CSI-RS) with different mapping strategies. CRS is mapped densely for accurate interference estimation, while CSI-RS provides channel quality information without compromising interference estimation accuracy.
Solution Approach 2:
The system transitions from a single reference signal serving both purposes to a two-dimensional approach using separate time-frequency resource allocations. This allows independent optimization of mapping density for interference estimation versus coverage for channel quality measurement.
3Adaptability or versatility
If existing reference signal configurations are used in LTE-A, then system compatibility is maintained, but interference estimation accuracy deteriorates
Solution Approach 1:
The system dynamically adapts the reference signal configuration by introducing configurable parameters such as subframe period, cyclic shift, and puncture patterns. This allows the system to maintain backward compatibility with existing LTE configurations while enabling enhanced interference estimation accuracy through optimized CSI-RS mapping when needed.
Solution Approach 2:
The invention changes key parameters of the reference signal configuration including mapping position, resource element allocation, and puncture patterns. These parameter changes enable accurate interference estimation in LTE-A systems while maintaining compatibility with existing LTE infrastructure through configurable activation and fallback mechanisms.
Data Source
AI summary
To provide a radio base station apparatus, mobile terminal device and wireless communication method for transmitting and receiving downlink channel quality measurement reference signals in consideration of interference estimation of high accuracy, in a wireless communication method of the invention, a radio base station apparatus generates channel quality measurement reference signals, and maps the channel quality measurement reference signals to two adjacent symbols, and a mobile terminal device receives a downlink signal including the channel quality measurement reference signals mapped to two adjacent symbols, and performs interfering power estimation using the channel quality measurement reference signals mapped to two adjacent symbols.