External Amplifier Interference Cancellation via Phase Shifting
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Solution Overview
Problem
External mounted amplifiers (EMAs) face challenges in effectively canceling interference in radio frequency signals received at base station antennas, which affects signal quality and noise reduction.
Innovation Solution
A system comprising dual low-noise amplifiers with a digital or analog signal processor that splits and phases signals to create cancellation signals, mixing them with input signals to remove interference, thereby enhancing signal quality and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If filters are used to limit bandwidth and improve signal to noise ratio, then noise and interference outside pass-band are reduced, but interferers within the pass-band cannot be removed and signal quality deteriorates
Solution Approach 1:
The patent segments the interference cancellation process into multiple stages: initial filtering to remove out-of-band noise, followed by adaptive interference cancellation to remove in-band interferers. This multi-stage approach allows each stage to address specific types of interference without compromising the other, resolving the contradiction between noise reduction and signal quality preservation.
Solution Approach 2:
The patent employs adaptive filtering techniques that dynamically adjust filter parameters based on the received signal characteristics. By continuously optimizing filter coefficients to match the actual interference patterns, the system can effectively remove in-band interferers while preserving desired signals, thus improving signal quality without being limited by fixed pass-band constraints.
2Reliability
If external mounted amplifiers are positioned close to radiating antennas for low-noise amplification, then signal quality is improved, but interference cancellation becomes more difficult due to the external mounting location
Solution Approach 1:
The patent introduces an adaptive interference cancellation module as an intermediary between the EMA and the receiver. This module acts as a mediator that processes the amplified signal to remove interference before the signal reaches the receiver, thereby maintaining signal quality improvement from the EMA while adding interference cancellation capability without requiring internal receiver modification.
Solution Approach 2:
The patent performs interference cancellation as a preliminary action before the signal is processed by the main receiver. By removing interference early in the signal chain, just after amplification, the system simplifies the overall complexity because subsequent receiver stages deal with already-cleaned signals, reducing the computational burden on the receiver itself.
3Measurement precision
If filters are used to condition RF signals at EMAs, then signal to noise ratio is improved for signals within pass-band, but the device complexity increases due to additional filtering components
Solution Approach 1:
The patent designs the filtering system to serve multiple functions: initial noise filtering, adaptive interference cancellation, and signal conditioning. By making the filter system multi-functional, the patent avoids adding separate dedicated components for each function, thereby improving signal to noise ratio through comprehensive filtering while minimizing the increase in device complexity through shared infrastructure.
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
The system effectively cancels interference and improves signal quality by using phase-shifting and mixing techniques, leading to better noise reduction and signal clarity for base station antennas.
Implementation Method 1
The first phase shifter is operable to shift the phase of first sampling signal to create a second cancelation signal
Implementation Method 2
The second mixer is operable to mix a second input signal derived from second signal with second cancelation signal to create a second output signal
Data Source
AI summary
A system includes a first external mounted amplifier (EMA) having a first low-noise amplifier (LNA) coupled to a first antenna, a second EMA having a second LNA coupled to a second antenna, a first splitter coupled between the first antenna and the first LNA, a first phase shifter coupled to the first splitter, and a second mixer coupled to the first phase shifter. The first LNA is operable to receive a first input signal from first antenna. The second LNA is operable to receive a second input signal from second antenna. The first splitter is operable to derive a first sampling signal from first signal. The first phase shifter is operable to shift the phase of first sampling signal to create a second cancelation signal. The second mixer is operable to mix a second input signal derived from second signal with second cancelation signal to create a second output signal.