Interference Cancellation Apparatus Using Multiple Schemes
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Solution Overview
Problem
In orthogonal frequency division multiplexing (OFDM) wireless transmission systems, existing interference cancellation methods, such as MRC and LS schemes, often fail to provide optimal performance due to varying interference levels and magnitudes, making it difficult to achieve effective interference cancellation, especially when the interference exceeds the desired signal at the cell edge.
Innovation Solution
A method and apparatus that convert received signals to frequency domain signals, apply multiple interference cancellation schemes, measure residual interference, and select the signal with the least residual interference, utilizing multiple antennas, converters, interference cancellation units, variance detectors, and an output selecting unit to optimize interference cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single interference cancellation scheme (MRC or LS) is used, then the device complexity is reduced, but the interference cancellation performance becomes suboptimal in varying interference environments
Solution Approach 1:
The interference cancellation unit is segmented into multiple parallel processing paths, each implementing a different cancellation scheme (MRC and LS). Each path processes the received signal independently through its own converter and processing unit, allowing both schemes to operate simultaneously without interfering with each other. This segmentation enables the system to evaluate multiple approaches and select the optimal one based on residual interference measurement.
Solution Approach 2:
The system dynamically switches between different interference cancellation schemes based on real-time measurement of residual interference. The output selecting unit receives interference-canceled signals from multiple schemes and selects the one with the least residual interference, making the system adaptive to changing interference conditions. This dynamic selection mechanism allows the system to optimize performance without requiring manual reconfiguration.
2Reliability
If multiple interference cancellation schemes are applied simultaneously, then the interference cancellation performance is optimized, but the device complexity increases
Solution Approach 1:
Multiple interference cancellation schemes are merged into a single integrated unit that processes all schemes through a common received signal input. The converters and processing units for different schemes share the same structural framework, and their outputs are combined at the output selecting unit. This merging approach allows the system to achieve optimal performance through multiple schemes while minimizing the increase in overall device complexity through shared components.
3Reliability
If interference is treated as noise using MRC scheme, then the signal-to-noise ratio is improved, but the interference cancellation is insufficient when interference magnitude exceeds desired signal
Solution Approach 1:
The system creates multiple copies of the received signal, with each copy being processed through a different interference cancellation scheme. One copy goes through MRC treatment while another goes through LS treatment. By having separate signal copies for different processing approaches, the system can compare the effectiveness of each scheme and select the one that produces the least residual interference, thereby overcoming the limitations of treating interference as noise in high-interference environments.
Data Source
AI summary
An apparatus for canceling interference includes a plurality of converters, a plurality of interference cancellation units, a plurality of variance detectors, and an output selecting unit. The plurality of converters converts a plurality of received signals to a plurality of frequency domain signals, respectively. The plurality of interference cancellation units cancel interference in the plurality of frequency domain signals using a plurality of interference cancellation schemes to generate a plurality of interference-canceled signals corresponding to the plurality of interference cancellation schemes, respectively. The plurality of variance detectors measure a plurality of amounts of residual interference corresponding to the plurality of interference-canceled signals, respectively. The output selecting unit selects a single interference-canceled signal with the least amount of residual interference from the plurality of interference-canceled signals, based on the plurality of amounts of residual interference.