In-band SRS Calculation for Multi-Antenna Channel Estimation
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Solution Overview
Problem
Current channel estimation methods in multi-antenna transmission systems require additional Sounding Reference Signals (SRS) equal to the number of transmitting antenna ports, leading to increased overhead and incomplete channel information due to precoding applied to Demodulation Reference Signals (DMRS).
Innovation Solution
The method calculates the difference between the number of transmitting antenna ports and the number of layers of currently transmitted DMRSs to determine the number of in-band SRSs needed, allowing for complete channel estimation with reduced overhead by transmitting only the necessary SRSs, ensuring the total number of reference signals equals the number of transmitting antenna ports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If the number of SRSs is increased to equal the number of transmitting antenna ports to achieve complete channel information estimation, then the completeness of channel information is improved, but the overhead is increased
Solution Approach 1:
The patent applies partial action by transmitting only the necessary number of SRSs (difference between Ntx and Nrank) rather than the full Ntx SRSs required by prior art. Since DMRS already provides channel information for Nrank layers, only the remaining Ntx-Nrank SRSs are needed to complete the channel matrix estimation, achieving complete channel information with reduced overhead.
2Quantity of substance
If the number of in-band SRSs is reduced to decrease overhead, then the overhead is reduced, but the completeness of channel information estimation deteriorates
Solution Approach 1:
The patent changes the parameter of SRS quantity from the traditional Ntx (equal to transmitting antenna ports) to Ntx-Nrank (difference between transmitting antenna ports and DMRS layers). This parameter optimization maintains complete channel information estimation by leveraging the complementary relationship between precoded DMRS and non-precoded SRS.
3Productivity
If precoding is applied to DMRSs to improve transmission efficiency, then the transmission efficiency is improved, but the ability to estimate complete channel information deteriorates
Solution Approach 1:
The patent segments the channel estimation function into two parts: DMRS handles the precoded channel estimation for Nrank layers, while SRS handles the remaining Ntx-Nrank antenna ports. This segmentation allows DMRS to maintain precoding for efficiency while SRS complements the estimation to achieve complete channel information.
Solution Approach 2:
The patent introduces SRS as an intermediary reference signal that bridges the gap left by precoded DMRS. Since DMRS with precoding cannot directly reveal the full channel matrix H, SRS serves as a mediator transmitted without precoding to enable the receiving end to estimate the complete channel information.
Data Source
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AI summary
A channel estimation method, comprising when it is determined that in-band SRSs are required to be transmitted, acquiring the number of transmitting antenna ports and the number of layers of the currently transmitted DMRSs; calculating the difference of the number of the transmitting antenna ports and the number of layers of the currently transmitted DMRSs, and using the difference as the number of in-band SRSs that are required to be transmitted; transmitting in-band SRSs to a receiving-end device according to the number of in-band SRSs that are required to be transmitted, to enable the receiving-end device to perform channel estimation according to the currently transmitted DMRSs and the received in-band SRSs. A channel estimation method, comprising receiving in-band SRSs transmitted from a transmitting-end device, the number of the in-band SRSs being the difference of the number of transmission antenna ports on the transmitting-end device and the number of layers of the currently transmitted DMRSs; performing channel estimation according to the received in-band SRSs and the currently transmitted DMRSs. A transmitting-end device, a receiving-end device and a communication system are also provided.