CSI Reporting Codebook Structure for Interference Management
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Solution Overview
Problem
In wireless communications, particularly in LTE systems, the deployment of low-power nodes in macrocell networks leads to interference issues, where macro base stations interfere with low-power nodes and user equipment, necessitating almost blank subframes to reduce interference, which wastes scheduling resources and limits flexibility.
Innovation Solution
A CSI reporting method that adjusts the codebook structure to select a suitable precoding matrix based on interference situations, allowing for efficient antenna selection and power allocation to minimize scheduling resource wastage by optimizing precoding matrix indicators and rank indicators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If almost blank subframes are used to reduce interference from macro base stations to low-power nodes, then interference is reduced, but scheduling resources are wasted and flexibility is limited
Solution Approach 1:
The patent changes the parameter of transmit power dynamically by using precoding matrix selection instead of semi-persistent ABS configuration. The UE selects precoding matrices from different codebook subsets (first subset for macro base station, second subset for low-power node) based on channel conditions, enabling flexible power control without wasting scheduling resources.
Solution Approach 2:
The patent introduces dynamic precoding matrix selection where the UE can switch between different codebook subsets based on real-time channel state information. This dynamic adaptation allows the system to respond to changing interference conditions without the rigidity of semi-persistent ABS configuration, improving scheduling flexibility.
2Object-affected harmful factors
If semi-persistent ABS configuration is used for interference coordination, then interference is reduced, but time-frequency resources are wasted
Solution Approach 1:
The patent enables the UE to autonomously select appropriate precoding matrices from different codebook subsets based on its own channel state information and interference measurements. This self-service mechanism eliminates the need for semi-persistent ABS configuration signaling, allowing the UE to adapt to interference conditions without consuming additional time-frequency resources for configuration.
3Stability of the object's composition
If codebook with constant modulus precoding matrices is used, then every antenna port can transmit data with constant power, but adaptability to interference situations is reduced
Solution Approach 1:
The patent segments the codebook into multiple subsets, where the first codebook subset contains precoding matrices suitable for macro base station transmission and the second codebook subset contains precoding matrices suitable for low-power node transmission. The UE selects from the appropriate subset based on the detected interference situation, maintaining constant modulus properties within each subset while achieving adaptability through subset selection.
Data Source
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AI summary
The present invention provides a channel state information CSI reporting method, including: receiving a reference signal from a base station; selecting, based on the reference signal, a precoding matrix from a codebook, where the codebook includes a precoding matrix W and W=αSV, where a matrix V is an N×ν matrix, N is the number of reference signal ports, ν ≤ N, S is a row selection matrix used to select one or more row vectors from the matrix V, and α is a constant; and sending CSI to the base station, where the CSI includes a precoding matrix indicator PMI and the PMI is corresponding to the selected precoding matrix. In the embodiments of the present invention, by means of codebook structure adjustment, a suitable precoding matrix can be selected according to an interference situation, so as to select an antenna for transmitting data and power of the antenna to reduce the amount of scheduling resources wasted due to interference control by a base station.