CSI-RS Pilot Pattern Allocation for Multi-Cell Channel Measurement
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Solution Overview
Problem
In the LTE Release 11 protocol, base stations face challenges in configuring channel state information reference signals (CSI-RS) for multiple joint cells, limiting the UE's ability to measure and feed back channel state information across multiple service points, which is essential for coordinated multiple point transmission and reception (CoMP) technology.
Innovation Solution
The method involves dividing access points into two sets and configuring distinct CSI-RS pilot patterns for each set, allowing each access point to send non-zero power CSI-RS according to its allocated pattern, enabling the UE to measure and report downlink channel state information from multiple access points, and generating joint channel state information by combining the reported data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the base station configures only one CSI-RS for the UE at most (as in LTE Release 10), then the configuration is simple, but the UE cannot measure channel state information of multiple joint cells for CoMP technology
Solution Approach 1:
The patent divides multiple access points into a serving access point set and a coordinating access point set. The serving access points transmit CSI-RS that the UE can measure and report, while coordinating access points transmit CSI-RS that the UE measures but does not report. This segmentation allows the UE to measure channel state information of multiple joint cells without requiring the base station to configure a single complex CSI-RS, thereby resolving the contradiction between measurement capability and configuration complexity.
2Measurement precision
If the base station configures three CSI-RSs for the UE at most (as in LTE Release 11), then the UE can measure CSI of multiple cells, but the UE cannot directly measure and feed back channel adjustment information among the cells
Solution Approach 1:
The patent introduces a dual-mode CSI-RS mechanism where the UE measures CSI-RS from both serving access points (for feedback) and coordinating access points (for reference). The base station uses these measurements to calculate joint channel state information and generate precoding matrices. This intermediary measurement approach enables the UE to indirectly contribute to joint channel state information without directly feeding back complex multi-cell channel adjustment information, resolving the contradiction between measurement precision and information feedback loss.
3Measurement precision
If multiple access points transmit CSI-RS simultaneously, then the UE can measure channel state information of multiple access points, but resource element conflicts and interference occur
Solution Approach 1:
The patent employs different periodicities and subframe offsets for serving access point CSI-RS and coordinating access point CSI-RS. By staggering the transmission timing of CSI-RS from different access points, the system reduces resource element conflicts and interference while still enabling the UE to measure channel state information of multiple access points. This periodic action approach resolves the contradiction between measurement precision and interference.
Data Source
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AI summary
Embodiments of the present invention provide a method for configuring a channel state information reference signal, a base station, and an access point. The method includes: dividing access points into a first access point set and a second access point set, configuring a first CSI-RS pilot pattern for a user equipment and allocating the pattern to the first access point set, configuring a second CSI-RS pilot pattern and allocating the pattern to the second access point set, and configuring a third CSI-RS pilot pattern and allocating the pattern to an antenna set formed by a first antenna of a first access point in the first access point set and a first antenna of a first access point in the second access point set, so that each access point sends a non-zero power on respective pilot patterns; and sending non-zero power CSI-RS configuration information to the user equipment, so that the user equipment measures and reports first downlink channel state information, second downlink channel state information, and third downlink channel state information of the antenna set. The base station obtains joint downlink channel state information according to the downlink channel state information.