Downlink Channel Information Acquisition with Combined Weight Matrices
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Solution Overview
Problem
Existing methods for obtaining downlink channel information in MIMO systems suffer from low accuracy and poor real-time performance due to the unbalanced receiving and transmitting capabilities of user equipment, particularly in TDD systems, where the time interval between uplink and downlink transmissions limits the precision and speed of channel estimation.
Innovation Solution
A method involving the network side device receiving a first pilot signal from user equipment using multiple antenna ports, determining a weight matrix based on channel gain, sending a second pilot signal, and combining the weight matrices to obtain comprehensive downlink channel information, utilizing precoding matrix indicators (PMI) to enhance accuracy and reduce time intervals for measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the UE sends SRS by using multiple antenna ports in separate time intervals to obtain downlink channel information, then the channel information can be obtained for all antenna ports, but the real-time performance deteriorates and measurement accuracy decreases due to the time interval required
Solution Approach 1:
The patent combines uplink channel measurement results from multiple antenna ports with downlink channel measurement results to form comprehensive downlink channel information. By merging the weight matrix from uplink measurement with PMI from downlink measurement, the system obtains accurate downlink channel information for all antenna ports simultaneously, eliminating the need for sequential measurements across different time intervals.
2Adaptability or versatility
If the UE uses unbalanced transmitting and receiving antenna ports (e.g., 2T4R, 4T8R), then the hardware configuration is optimized for practical scenarios, but the accuracy of downlink channel information obtained through reciprocity deteriorates
Solution Approach 1:
The patent segments the downlink channel information acquisition process into two parts: obtaining a weight matrix through uplink channel measurement using transmitting antenna ports, and obtaining PMI through downlink channel measurement using receiving antenna ports. This segmentation allows the system to handle unbalanced antenna configurations (e.g., 2T4R, 4T8R) effectively by treating uplink and downlink measurements as complementary components that together form complete downlink channel information.
3Reliability
If the base station performs beamforming using downlink channel information, then communication quality improves, but the system complexity increases due to the need for accurate channel estimation and weight matrix calculation
Solution Approach 1:
The patent enables the system to self-determine downlink channel information by having the UE autonomously measure uplink channels and generate weight matrices, then combine these with downlink PMI measurements. This self-service approach reduces the base station's computational burden for channel estimation, as the UE performs part of the measurement work and provides results that the base station can directly utilize for beamforming, thereby reducing system complexity while maintaining communication quality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves the accuracy and real-time performance of downlink channel information acquisition by concatenating weight matrices, allowing for more precise and timely estimation of channel conditions across multiple antenna ports.
Implementation Method 1
In a time division duplex (English: time division duplex, TDD for short) system, a same channel is used for uplink transmission and downlink transmission. Therefore, the base station can estimate the downlink channel information by measuring the uplink channel based on channel reciprocity.
Data Source
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AI summary
A method and an apparatus for obtaining downlink channel information are provided to resolve a problem in the prior art that obtained downlink channel information is of low accuracy. The method includes: receiving, by a network side device, a first pilot signal sent by user equipment by using N first antenna ports, and determining, based on the received first pilot signal, a downlink channel gain matrix corresponding to the N first antenna ports; determining, based on the downlink channel gain matrix corresponding to the N first antenna ports, a first weight matrix corresponding to the N first antenna ports; sending, by the network side device, a second pilot signal to the user equipment, receiving a precoding matrix indicator PMI fed back by the user equipment; determining a second weight matrix based on the PMI; and determining, by the network side device based on the first weight matrix and the second weight matrix, downlink channel information that corresponds to the N first antenna ports and that corresponds to the M second antenna ports.