Uplink Reference Signal Carrying Downlink Channel Data
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Solution Overview
Problem
In wireless mobile communication systems, especially those using frequency division duplexing (FDD), base stations face challenges in accurately converting uplink channel status to downlink channel status due to different frequency bands, hindering effective channel information transmission and impacting spectrum efficiency and service quality.
Innovation Solution
The method involves a user device generating and transmitting uplink reference signals that carry downlink channel estimation values to the base station, allowing the base station to decode downlink channel information through pre-coding and noise estimation processes, regardless of channel symmetry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If frequency division duplexing (FDD) is used to separate uplink and downlink frequencies, then spectral efficiency is improved, but accurate conversion between uplink and downlink channel status becomes difficult due to frequency asymmetry
Solution Approach 1:
The patent introduces an intermediary transformation process where the downlink channel matrix is converted to an uplink channel matrix through a predetermined transformation relationship. This intermediary mathematical transformation allows the system to bridge the frequency asymmetry gap between uplink and downlink channels, enabling accurate channel status conversion despite the FDD frequency separation.
Solution Approach 2:
The patent changes the parameter representation of channel information by transforming the downlink channel matrix into an uplink channel matrix through mathematical operations. This parameter transformation allows the system to adapt channel status from one frequency band to another, resolving the accuracy issue caused by FDD frequency separation while maintaining spectral efficiency.
2Productivity
If multi-antenna techniques are deployed to increase throughput, then transmission performance is improved, but accurate downlink channel information acquisition becomes critical and complex
Solution Approach 1:
The patent inverts the traditional approach by having the user equipment estimate the downlink channel matrix and then transform it to the uplink channel matrix, rather than having the base station directly estimate the uplink channel. This inversion leverages the reciprocity principle in reverse, allowing the system to acquire accurate downlink channel information for multi-antenna processing while simplifying the overall acquisition process.
Solution Approach 2:
The patent implements a feedback mechanism where the user equipment estimates the downlink channel matrix, transforms it to the uplink channel matrix, and feeds back the transformed information to the base station. This feedback loop enables the base station to acquire accurate channel information for multi-antenna techniques while reducing the complexity of direct channel estimation at the base station.
3Productivity
If uplink reference signals are designed to carry downlink channel information, then channel information transmission efficiency is improved, but signal processing complexity increases
Solution Approach 1:
The patent merges the downlink channel estimation function with the uplink reference signal transmission. The user equipment estimates the downlink channel matrix and embeds this information into the uplink reference signal through mathematical transformation. This merging allows efficient channel information transmission using existing uplink reference signal resources while avoiding the need for separate dedicated feedback channels.
Solution Approach 2:
The patent makes the uplink reference signal serve multiple functions: it acts as both a standard uplink reference signal for uplink channel estimation and as a carrier for downlink channel information. This multi-functionality improves transmission efficiency by utilizing existing signal structures while reducing the need for additional dedicated signaling resources.
Data Source
AI summary
A method for transmitting channel information, adapted to a base station, includes steps of: receiving a first uplink reference signal and a second uplink reference signal from a user device, obtaining an uplink channel estimation value according to the first uplink reference signal, and obtaining a downlink channel estimation value according to the second uplink reference signal and the uplink channel estimation value.