CSI Feedback Segmentation for Coordinated Multi-Point Systems
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Solution Overview
Problem
Current CSI feedback methods in coordinated multi-point communication systems, especially in LTE-A systems, face challenges in supporting advanced transmission schemes like Joint Transmission (JT) due to high overhead and limited accuracy, particularly in multi-antenna multi-TP coordination scenarios.
Innovation Solution
A novel CSI feedback method and user equipment (UE) implementation that acquires and calculates CSI processes configured by multiple transmission points (TPs), incorporating inheritance mechanisms for RI and SB configurations, to efficiently feed back channel state information, optimizing feedback classes and modes for JT and frequency-domain DPS/DPB transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional CSI feedback methods are used in coordinated multi-point communication, then the system can maintain backward compatibility with existing LTE-A systems, but the feedback overhead becomes excessively high and the accuracy is limited for advanced transmission schemes like Joint Transmission
Solution Approach 1:
The patent segments the CSI feedback into multiple processes (first CSI process and second CSI process) with different levels of detail. The first CSI process provides basic feedback while the second CSI process provides enhanced feedback for coordinated transmission, allowing the system to segment information based on transmission mode requirements and reduce overall overhead.
Solution Approach 2:
The patent introduces dynamic configuration where the network can flexibly configure which CSI processes to use based on the transmission scheme. The eNodeB can configure RI inheritance and SB inheritance dynamically, allowing the system to adapt the feedback mechanism to current transmission needs rather than using a fixed overhead structure.
2Measurement precision
If complete channel state information is fed back for multi-antenna multi-TP coordination, then the measurement precision and reliability improve, but the signaling overhead increases significantly
Solution Approach 1:
The patent applies local quality by providing different levels of CSI detail for different transmission points. The first CSI process provides basic local feedback for each TP, while the second CSI process provides enhanced feedback only when coordinated transmission is needed, allowing high precision where required and reduced precision where sufficient.
Solution Approach 2:
The patent uses partial action by requiring the UE to report only the necessary CSI components for the current transmission mode. Through RI inheritance mechanisms, the system avoids requesting redundant CSI information, implementing partial feedback that suffices for the given transmission scheme without excessive overhead.
3Adaptability or versatility
If multiple CSI processes are configured for multi-TP coordination, then the system can support advanced CoMP transmission schemes, but the device complexity increases
Solution Approach 1:
The patent makes the CSI processes universal by designing them to serve multiple purposes. The same CSI process configuration can support both traditional single-TP transmission and coordinated multi-TP transmission. The inheritance mechanisms work universally across different transmission schemes, reducing the need for separate specialized configurations.
Solution Approach 2:
The patent uses feedback mechanisms where the eNodeB configures which CSI processes to use based on observed transmission conditions and UE capabilities. This feedback loop allows the system to manage complexity dynamically, activating only the necessary CSI processes for current operations rather than maintaining all possible configurations simultaneously.
Data Source
AI summary
The present disclosure provides a method in a UE for feeding back channel state information (CSI) and the UE. The method comprises: acquiring a set of CSI processes which are configured by a transmission point (TP) to participate in multi-antenna multi-TP coordination; acquiring a sub-band (SB) inheritance which is configured by a TP for a CSI process from the set of CSI processes; calculating the CSI based on the configuration for the CSI process; and feeding the calculated CSI back to a TP. The present disclosure has the advantages of simple implementation and low signalling overhead and is applicable to enhanced 4G systems and to 5G systems.