OAM Full-Duplex Interference Cancellation Using Signal Replicas
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Solution Overview
Problem
Full-duplex wireless communication systems using orbital angular momentum (OAM) face significant self-interference issues due to the orthogonality of OAM multiplexing, which current methods fail to adequately address, leading to noise in received signals.
Innovation Solution
A communication device equipped with an interference cancellation circuit that generates and subtracts replicas of interference signals, using Butler matrix circuits and uniform circular array antennas to separate and cancel both intra- and inter-antenna interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If full-duplex wireless communication using OAM is implemented, then transmission and reception can be performed simultaneously using the same frequency, but self-interference occurs when transmitted signals turn around into receiving antennas
Solution Approach 1:
The patent segments the interference cancellation process into multiple independent components: intra-antenna interference cancellation and inter-antenna interference cancellation. Each component processes specific interference types separately, allowing comprehensive cancellation while maintaining full-duplex operation. The receiving antenna group and transmitting antenna group are also segmented to handle different interference paths.
Solution Approach 2:
The patent creates replicas (copies) of the transmitted signal to represent the interference signal. By generating a copy of the transmitted signal and processing it through the same channel effects, the system can accurately subtract the interference from the received signal without directly measuring the interference path.
2Device complexity
If only orthogonality of OAM multiplexing is used for separation between transmission and reception, then the system structure remains simple, but self-interference cannot be reduced sufficiently
Solution Approach 1:
The patent introduces an intermediary interference cancellation unit that mediates between the received signal and the transmitted signal. This unit processes the transmitted signal to generate an interference replica and subtracts it from the received signal, acting as a bridge to eliminate self-interference while maintaining the simplicity of using only OAM orthogonality for signal separation.
3Reliability
If interference cancellation is implemented, then received signal quality improves, but device complexity increases due to additional circuits
Solution Approach 1:
The patent merges the interference cancellation function with the existing OAM signal processing chain. The interference cancellation unit is integrated into the receiving device's signal processing path, sharing resources with the OAM mode separation and Butler matrix operations. This combining approach reduces overall system complexity compared to adding completely separate interference cancellation hardware.
Data Source
AI summary
A communication device according to the present invention is a communication device that wirelessly communicates with a counterpart communication device in a full-duplex mode using orbital angular momentum, and includes a second interference cancellation circuit that generates a replica of an interference signal received together with one or more signals transmitted from the counterpart communication device, on the basis of one or more signals to be transmitted to the counterpart communication device, and subtracts the replica from a received signal.