Near-Field Self-Interference Cancellation in Full Duplex Systems
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Solution Overview
Problem
In wireless full duplex communications, near-field reflected self-interference signals are difficult to effectively cancel due to their short propagation distance and small delay difference, making it challenging to recognize and reconstruct these signals using normal bandwidths, which hinders spectral efficiency.
Innovation Solution
A method and apparatus that send a sounding signal with a greater bandwidth than the communication signal, allowing for the separation and processing of near-field reflected signals to determine the near-field reflection channel parameter, and subsequently subtract the reconstructed self-interference signal from the received communication signal, using techniques like matched filtering or super-resolution delay algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If normal bandwidth is used for communication, then power consumption is reduced, but near-field reflected self-interference signal cannot be effectively recognized and reconstructed
Solution Approach 1:
The patent applies preliminary action by sending a sounding signal before the actual communication signal to characterize the near-field reflection channel. This preliminary channel characterization enables subsequent effective cancellation of self-interference signals during communication, resolving the contradiction between using normal bandwidth (lower energy) and achieving sufficient signal recognition accuracy.
2Reliability
If sounding signal is sent continuously, then near-field reflection channel is continuously characterized, but interference to communication signal increases
Solution Approach 1:
The patent implements periodic action by sending sounding signals only in specific time slots rather than continuously. The sounding signal is transmitted periodically to update channel characterization while remaining silent in other time slots to avoid interfering with communication signals, thus balancing channel accuracy with interference reduction.
3Measurement precision
If sounding signal power is increased, then channel parameter estimation accuracy improves, but interference to communication signal worsens
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the power of the sounding signal based on channel conditions and communication requirements. The sounding signal power is set to an appropriate level that provides sufficient channel characterization accuracy while minimizing interference to ongoing communications, rather than using fixed high power.
4Productivity
If wireless full duplex is implemented, then spectral efficiency doubles, but self-interference cancellation becomes extremely difficult
Solution Approach 1:
The patent applies segmentation by dividing the self-interference cancellation process into distinct components: near-field reflection channel characterization using sounding signals, and separate cancellation processing for different signal components. This segmentation of the interference cancellation task makes the complex full duplex operation more manageable and effective.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables effective reduction of near-field self-interference signals, improving the accuracy of received signals and enhancing spectral efficiency in wireless full duplex systems by accurately determining and canceling near-field reflected self-interference.
Implementation Method 1
Self-interference includes a near-field reflected self-interference signal on a near-field reflection channel and a far-field reflected self-interference signal on a far-field reflection channel. The near-field reflected self-interference signal typically corresponds to a near-field reflection path of 0.3 m to 60 m, and a multi-path transmission delay is 1 ns to 400 ns.
Implementation Method 2
a receive antenna configured to receive an echo signal, where the echo signal includes a near-field reflected signal corresponding to the sounding signal
Data Source
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AI summary
Embodiments of the present invention provide a method for reducing a self-interference signal in a communications system, and an apparatus, where the method includes: sending a sounding signal; receiving an echo signal, where the echo signal includes a near-field reflected signal corresponding to the sounding signal; separating the near-field reflected signal corresponding to the sounding signal from the echo signal; determining a near-field reflection channel parameter according to the near-field reflected signal; determining a reconstructed near-field reflected self-interference signal based on the near-field reflection channel parameter; and subtracting the reconstructed near-field reflected self-interference signal from a received second communication signal. According to the method and apparatus that are provided by the present invention, a near-field reflection channel parameter used to estimate a near-field reflected self-interference signal can be determined, and near-field reflected self-interference signals in signals received from another apparatus are reduced by using the near-field reflection channel parameter.