Virtual Reference Signal for Downlink Channel Estimation
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Solution Overview
Problem
In multi-user multiple input multiple output (MU-MIMO) systems, accurate downlink channel estimation is challenging due to channel estimation errors and quantization-induced information loss, leading to imperfect interference control and degraded reception performance.
Innovation Solution
A method and apparatus for estimating a downlink channel using a virtual reference signal (RS) selected based on the accuracy of recovered data, correlation between signal positions, and average channel error, allowing for iterative detection and improved channel estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If orthogonal reference signals are used for channel estimation in MU-MIMO system, then interference between users is reduced, but channel estimation accuracy deteriorates due to frequency changes and time passage
Solution Approach 1:
The patent applies preliminary action by performing channel estimation at multiple time points (initial channel estimation before data transmission, and subsequent channel estimations at different time points during data transmission) and combining these estimates. This preliminary multi-point sampling approach captures channel variations over time and frequency, enabling more accurate compensation for channel changes while maintaining interference reduction through orthogonal reference signals.
Solution Approach 2:
The patent implements feedback by using the initially estimated channel information to guide subsequent channel estimation processes. The receiver feeds back the relationship between reference signals and data signals, and uses this feedback to adjust and refine channel estimates at different time points, thereby improving overall estimation accuracy while maintaining orthogonal signal structure for interference management.
2Reliability
If beamforming is applied based on downlink channel information, then reception performance is improved, but performance deteriorates due to channel estimation errors and quantization information loss
Solution Approach 1:
The patent performs preliminary channel estimation before beamforming application, and then updates channel estimates at multiple subsequent time points during data transmission. This preliminary and continuous estimation approach ensures that beamforming uses the most accurate available channel information, compensating for estimation errors and quantization losses by having multiple measurement opportunities to work with.
Solution Approach 2:
The patent applies dynamics by making the channel estimation process adaptive and time-varying. Instead of using a static channel estimate, the system continuously updates channel information at different time points and combines these dynamic estimates, allowing beamforming to adapt to changing channel conditions while mitigating the impact of individual estimation errors and quantization effects.
3Object-generated harmful factors
If multi-user signal detection is performed to handle imperfect beamforming, then interference processing capability is improved, but detection accuracy is limited by imperfect channel estimation
Solution Approach 1:
The patent performs preliminary channel estimation and uses this information to guide the multi-user signal detection process. By having accurate preliminary channel estimates from multiple time points, the detection algorithm can better separate user signals and handle interference, improving detection accuracy despite the inherent imperfections in channel estimation and beamforming.
Solution Approach 2:
The patent implements feedback loops where channel estimation results from multiple time points are fed back into the signal detection process. This feedback mechanism allows the system to continuously refine its understanding of channel conditions and adjust detection parameters accordingly, improving detection accuracy by leveraging accumulated channel information while effectively processing interference from multiple users.
Data Source
AI summary
The present disclosure relates to a 5G or pre-5G communication system to be provided to support a higher data transmission rate beyond the 4G communication system, such as LTE. The present invention provides a method for estimating a downlink channel by a receiver in a wireless communication system, the method comprising: estimating the downlink channel on the basis of a reference signal to recover an information bit, and checking whether the information bit recovery has succeeded; and when the information bit recovery has not succeeded, selecting at least one of the received signals as a virtual reference signal on the basis of the accuracy of the data reconstructed at a related resource location and the correlation between the related resource location and a resource location related to the reference signal, and estimating the downlink channel on the basis of at least one virtual reference signal.