Base Station Channel Reciprocity Control
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Solution Overview
Problem
In a radio access network, deteriorated channel reciprocity between the uplink and downlink hinders accurate downlink beamforming and precoding, leading to poor signal quality and increased data decoding errors, especially when terminal apparatus movement or misalignment of transmitting and receiving antennas occurs.
Innovation Solution
A base station obtains downlink channel information based on a downlink channel estimate and uplink channel information based on an uplink channel estimate, using this correlation to perform control related to downlink transmission, thereby maintaining effective control even when channel reciprocity is deteriorated.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If channel reciprocity is used to estimate downlink channel quality, then downlink transmission control can be performed, but the accuracy deteriorates when uplink-downlink reciprocity is not ideal
Solution Approach 1:
The patent introduces a correlation calculation unit as an intermediary that processes both uplink and downlink channel information separately before combining them. This intermediary structure allows the system to handle cases where direct reciprocity fails by using correlated characteristics from both directions to infer accurate channel quality, thereby resolving the contradiction between measurement precision and reliability.
Solution Approach 2:
The patent replaces the direct mechanical assumption of perfect channel reciprocity with a statistical correlation-based approach. Instead of relying on the channel being identical in both directions, the system uses correlation analysis to find the statistical relationship between uplink and downlink channels, enabling accurate estimation even when perfect reciprocity does not hold.
2Productivity
If downlink transmission control is performed based on uplink channel estimate, then control can be maintained, but signal quality deteriorates when channel reciprocity is deteriorated
Solution Approach 1:
The patent merges the processing of uplink and downlink channel information by calculating their correlation and using both to determine downlink transmission control parameters. This combining approach allows the system to leverage information from both directions to maintain both productivity and signal quality, resolving the contradiction between transmission efficiency and signal reliability.
Solution Approach 2:
The patent implements a feedback mechanism where downlink channel information obtained from downlink estimates is fed back into the control process. This feedback loop allows the system to continuously adjust transmission parameters based on actual downlink conditions, ensuring both efficient transmission and high signal quality even when reciprocity is imperfect.
3Measurement precision
If calibration user terminal selection is used to improve reciprocity calibration, then measurement accuracy improves, but system complexity increases
Solution Approach 1:
The patent enables the system to perform self-calibration by automatically selecting calibration user terminals based on the correlation between uplink and downlink channel information. The system uses its own measured data to identify suitable calibration terminals and perform reciprocity calibration without external intervention, thereby improving measurement precision while keeping the calibration process self-managing and not excessively complex.
Data Source
AI summary
Even if the channel reciprocity established between the uplink and the downlink is deteriorated, control the transmission in the downlink is performed properly. A base station 100 includes: an information obtaining unit 143 configured to obtain downlink channel information based on a downlink channel estimate, and uplink channel information based on an uplink channel estimate; and a control unit 145 configured to perform control related to transmission in downlink channel based on a correlation between the downlink channel information and the uplink channel information.