WLAN Station Sphere Decoding for MU-MIMO Interference
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Solution Overview
Problem
In down-link (DL) multiple user multiple input multiple output (MU-MIMO) orthogonal frequency division multiplexing (OFDM) systems, interference signals disrupt the detection of desired signals, leading to performance degradation and error floors due to imperfect precoding caused by channel estimation and feedback errors.
Innovation Solution
A method for a wireless local area network (WLAN) station to estimate channels, separate desired and interference signal matrices, detect signals using sphere decoding, and generate a virtual channel by combining channel matrices to enhance signal reception and reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If precoding technology is used to transmit signals to multiple users, then signal interference is reduced, but channel estimation errors and feedback quantization errors cause imperfect precoding, resulting in residual interference signals that degrade reception performance
Solution Approach 1:
The patent converts the harmful residual interference signals into beneficial information by detecting them as additional signals. The interference signals, which were previously considered noise degrading performance, are now treated as detectable signals that can be separated and removed, thereby improving the overall reception performance and reducing the error floor phenomenon.
Solution Approach 2:
The patent segments the received signal into distinct components by separating the channel matrix into desired signal components and interference signal components. This segmentation allows independent detection and processing of each component, enabling the station to explicitly handle interference signals rather than treating them as不可分割 noise.
2Productivity
If the number of users in the system is increased, then spatial utilization is improved, but the sum of interference signal values increases, adversely affecting detection of desired signals
Solution Approach 1:
The patent implements a feedback mechanism where the station detects interference signals and uses this information to generate corrected channel matrices. The detected interference signals are fed back into the processing system to be subtracted from the received signal, thereby compensating for the increased interference caused by higher user density and maintaining detection accuracy.
3Ease of operation
If conventional detection methods are used assuming perfect precoding, then detection simplicity is maintained, but performance degradation occurs due to unaccounted interference signals
Solution Approach 1:
The patent performs preliminary detection of interference signals before final signal processing. By detecting and characterizing the interference signals in advance, the system can prepare corrected channel matrices and optimized detection parameters beforehand, enabling accurate desired signal detection even in complex multi-user environments without significantly increasing operational complexity.
Data Source
AI summary
A method of operating a wireless local area network (WLAN) station. The WLAN station receives at least one desired signal and at least one interference signal from an access point (AP) capable of simultaneously transmitting desired signals to multiple WLAN stations. The method includes estimating a channel and generating a channel matrix estimated based on the estimated channel, separating a channel matrix of the desired signal and a channel matrix of the interference signal from the estimated channel matrix, generating the matrix of a virtual channel by combining the separated channel matrixes, and executing a sphere decoding (SD) algorithm using the matrix of the virtual channel.Or, separating a desired signal and an interference signal from the stream signal based on the analysis result, ascertaining a modulation scheme of the interference signal, and setting the ascertained modulation scheme of the interference signal as decreased lattice points.