Joint Channel Estimation for UL CoMP Interference
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Solution Overview
Problem
In Coordinated Multipoint (CoMP) transmission/reception systems, particularly in uplink (UL) CoMP, the interference between locally scheduled and desired user signals due to overlapping frequency resources leads to inaccurate channel estimates, compromising the reliability of conventional Demodulation Reference Signal (DMRS)-based decision making.
Innovation Solution
A channel estimation system that jointly estimates channels for locally scheduled and desired users by processing a composite wideband signal, subtracting locally scheduled signals to isolate desired signals, and calculating channel estimates using overlapping frequency resources, ensuring accurate channel estimation and minimizing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional DMRS-based decision making is used in UL CoMP, then the system operation is simple, but channel estimation accuracy deteriorates due to interference from overlapping frequency resources
Solution Approach 1:
The patent segments the composite signal into individual user signals by identifying and separating signals from different UEs based on their reference sequences. This segmentation allows the system to estimate channels for each user independently, resolving the interference issue that plagues conventional approaches while maintaining manageable complexity through systematic signal separation.
Solution Approach 2:
The patent uses reference sequences as intermediary elements to detect and separate user signals. By correlating the received composite signal with known reference sequences, the system can identify which users are present and extract their individual signals, enabling accurate channel estimation without direct interference from other users' signals.
2Reliability
If all potential desired user signals are processed for channel estimation, then detection reliability improves, but processing time and computational load increase
Solution Approach 1:
The patent performs preliminary detection of desired user signals by correlating the composite signal with reference sequences before full channel estimation. This preliminary action identifies which users are actually present in the signal, allowing the system to focus processing only on detected users rather than all potential users, thus improving reliability while reducing processing time.
Solution Approach 2:
The patent applies partial action by processing only the subset of user signals that are actually detected and relevant to the current transmission, rather than exhaustively processing all potential desired user signals. This selective approach maintains detection reliability for active users while significantly reducing computational load and processing time.
Data Source
AI summary
A channel estimation system disclosed herein jointly estimates the channels for users transmitting signals allocated overlapping frequency resources in a received composite wideband signal. The channel estimation system may further limit the joint channel estimation process to only locally scheduled UEs and those desired users transmitting detectable desired signals using frequency resources at least partially overlapping the locally scheduled UE's frequency resources. More particularly, a local base station processes the received composite wideband signal to determine which of the potential desired user(s) have transmitted user signals allocated frequency resources that at least partially overlap the frequency resources allocated to locally scheduled users and having a sufficient signal strength and quality to be detectable as present in the received signal. The local base station processes the local and detected desired user signals in the received signal to jointly calculate channel estimates for the corresponding users based on the corresponding reference sequences.