Self-Interference Cancellation in Small Cell Backhaul
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Solution Overview
Problem
In wireless backhaul networks for small cell base stations, significant self-interference occurs due to the simultaneous transmission and reception of signals over the same channel, making it challenging to achieve high data rates while maintaining compactness and power efficiency.
Innovation Solution
Implementing a self-interference cancellation method at the baseband level using an RF impairment compensator and digital canceller to estimate and subtract the distortions caused by the transmitter chain from the receive signal, allowing for effective cancellation of self-interference without requiring analog domain processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If simultaneous transmission and reception over the same channel is implemented, then data rate is improved, but self-interference increases
Solution Approach 1:
The patent segments the self-interference cancellation process into multiple stages: analog domain cancellation using circulators and isolation circuits, followed by digital domain cancellation using signal processing algorithms. This multi-level segmentation allows progressive reduction of self-interference to enable full-duplex operation
Solution Approach 2:
The patent introduces circulators as intermediary devices between the transmitter and receiver antennas. These passive RF components redirect self-interference signals away from the receiver input, providing isolation without requiring active cancellation. The circulator acts as a mediator that physically separates the harmful interference path
2Object-generated harmful factors
If analog domain processing is used for self-interference cancellation, then self-interference reduction is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex analog self-interference cancellation hardware with digital signal processing algorithms. Instead of using analog adaptive filters and complex RF circuitry, the system captures the self-interference signal digitally and cancels it using computational methods, simplifying the hardware architecture
Solution Approach 2:
The patent changes the domain of processing from analog to digital. By sampling the self-interference signal and performing cancellation operations in the digital domain, the system avoids the complexity of analog signal manipulation while achieving equivalent or superior cancellation performance through programmable algorithms
Data Source
AI summary
To provide for higher data rates, a wireless back haul network for connecting small cell base stations to a core network can be implemented using full-duplex over single channel communications. The difficulty with full-duplex over single channel communications, and the reason why it has not become common place in wireless and mobile communication standards to date, is the significant interference that the receiver of a full-duplex communication device will generally experience from the full-duplex communication device's own transmitter transmitting over the same channel that the receiver is to receive signals. This interference is referred to as self-interference because the interference experienced by the receiver originates from its own paired transmitter. The present disclosure describes embodiments of an apparatus and method that provide sufficient self-interference cancellation in a compact and power efficient manner for a small cell wireless backhaul network.