Communication Circuit for Self-Interference Cancellation in Wireless Systems
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Solution Overview
Problem
Wireless distribution systems (WDSs) employing software-defined remote units face challenges with inadequate suppression of in-band and out-of-band leakages, leading to downlink-to-uplink interference, which reduces the sensitivity and dynamic range of uplink receivers due to the absence of hardware-based filters and duplexers.
Innovation Solution
A communication circuit in the head-end unit provides accurate temporal and phase estimates for interference signals in the uplink band by utilizing an anchor downlink signal to determine an optimal phase shift, enabling effective self-interference cancellation through phase-synchronized uplink signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If hardware-based filters and duplexers are removed to enable software-defined radio (SDR), then flexibility and adaptability improve, but in-band and out-of-band leakage suppression deteriorates
Solution Approach 1:
The patent replaces hardware-based filters and duplexers (mechanical/physical systems) with software-defined radio processing and self-interference cancellation algorithms. The SDR architecture uses digital signal processing to achieve filtering and duplexing functions that were traditionally performed by physical components, thereby maintaining flexibility while addressing interference suppression through software-based solutions.
Solution Approach 2:
The patent converts the harmful downlink-to-uplink interference caused by leakage into a measurable signal that can be used for calibration and self-interference cancellation. By characterizing the interference signal and using it to generate cancellation signals, the system transforms the harmful leakage into a useful reference for developing compensation mechanisms.
2Object-generated harmful factors
If downlink-to-uplink interference increases due to leakage, then the harmful factors worsen, but sensitivity and dynamic range of uplink receivers deteriorate
Solution Approach 1:
The patent applies preliminary anti-action by pre-characterizing the downlink-to-uplink interference signal and generating self-interference cancellation signals before the actual uplink reception. The system uses calibration procedures to model the interference path and prepares compensation signals that are subtracted from the received uplink signal, thereby preventing the interference from degrading receiver sensitivity and dynamic range.
3Device complexity
If self-interference cancellation is implemented without accurate synchronization, then device complexity increases, but interference suppression stability deteriorates
Solution Approach 1:
The patent implements feedback mechanisms where the system continuously monitors the effectiveness of self-interference cancellation and adjusts synchronization parameters accordingly. The calibration procedures provide feedback loops that measure residual interference and refine the cancellation signals, ensuring stable interference suppression while managing system complexity through adaptive adjustment rather than overly complex fixed architectures.
Data Source
AI summary
A communication circuit in a wireless communications system (WCS) is provided. The WCS employs self-interference cancellation (SIC) circuitry to suppress an interference signal(s) associated with an uplink communications signal(s) in a target uplink band(s). A communication circuit is employed to provide more accurate temporal and phase estimates about interference signal(s) in the target uplink band(s). The communication circuit utilizes an anchor downlink signal, which can be any of the downlink communications signals communicated in the WCS, to help determine an optimal phase shift for uplink communications signal(s) in the target uplink band(s). Accordingly, the SIC circuitry can suppress the interference signal(s) in the target uplink band(s) based on the optimal phase shift. By determining the optimal phase shift in the target uplink band(s), it is possible to achieve accurate temporal and phase synchronization in the SIC circuitry, thus helping to achieve higher and more stable interference suppression in the WCS.