Uplink Precoding Matrix Indication via Downlink Equivalent Channel
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Solution Overview
Problem
The precision of indicating uplink precoding matrices in 5G communication systems, whether codebook based or non-codebook based, is low, leading to inefficiencies in spectral efficiency.
Innovation Solution
A method involving channel estimation based on downlink reference signals to determine uplink precoding matrices, allowing precise indication without additional resource overhead, using downlink equivalent channels to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If codebook based uplink transmission or non-codebook based uplink transmission is used, then uplink transmission can be implemented, but the precision of indicating the uplink precoding matrix is low
Solution Approach 1:
The patent introduces a downlink reference signal as an intermediary carrier to convey uplink precoding matrix indication information. Instead of directly indicating the precoding matrix through DCI (which has limited precision), the system uses the downlink reference signal as a mediator that embeds the indication information, allowing the terminal to extract precise precoding matrix details through channel estimation and downlink equivalent channel calculation.
Solution Approach 2:
The patent changes the parameter representation method by using the downlink equivalent channel (derived from downlink reference signal) to indicate uplink precoding matrix information. This transforms the indication from direct index-based representation to a channel-based representation, enabling higher precision in conveying precoding matrix characteristics.
2Measurement precision
If additional resources are allocated to indicate uplink precoding matrix, then indication precision can be improved, but resource overhead increases
Solution Approach 1:
The downlink reference signal serves multiple functions: it is used for downlink channel estimation and simultaneously carries uplink precoding matrix indication information. This multi-functionality allows the system to improve indication precision without allocating additional dedicated resources, as the same reference signal resource accomplishes both tasks.
Solution Approach 2:
The patent merges the function of downlink channel estimation and uplink precoding matrix indication into a single process. The downlink reference signal is used for both purposes, and the terminal combines channel estimation results with indication information extraction, thereby improving precision while avoiding additional resource overhead.
Data Source
AI summary
This disclosure discloses an information indication method and an apparatus, to resolve a problem that indication precision of an uplink precoding matrix is low. The method includes: receiving a downlink reference signal sent by a network device on a first transmission resource; performing channel estimation based on the downlink reference signal, to obtain a downlink equivalent channel corresponding to the first transmission resource; and determining, based on the downlink equivalent channel, to-be-indicated information corresponding to a terminal device, where the to-be-indicated information indicates an uplink precoding matrix used when a first terminal device sends uplink data on the first transmission resource. The downlink equivalent channel is obtained by performing channel estimation based on the downlink reference signal.