Multi-Tier Interference Canceler for RF Dynamic Range
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Solution Overview
Problem
Conventional interference cancelers face challenges in handling high dynamic range co-site interference between high-power RF transmitters and receivers, as they require complex and costly analog cancellation techniques, which are difficult to implement due to limitations in conventional ADCs.
Innovation Solution
A multi-tier interference canceler system that includes a first canceler to sample RF interference using a non-linear process, a second canceler to receive an amplitude scaled and time-shifted version of the interference, and a third canceler to cancel non-linear interference using samples from the first canceler, effectively removing both linear and non-linear interference from the received signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional analog cancellation techniques are used to achieve broadband cancellation of high-level interference, then interference cancellation performance is improved, but device complexity, cost, and size increase significantly
Solution Approach 1:
The patent replaces complex analog cancellation techniques with a digital signal processing approach. A downconverter converts RF interference to baseband or intermediate frequency, followed by digital signal processing that separates linear and non-linear interference components. This substitution of mechanical/analog systems with digital processing reduces device complexity while maintaining cancellation effectiveness.
Solution Approach 2:
The patent changes the operating parameters by converting the signal from RF domain to baseband/intermediate frequency domain through downconversion. This parameter change enables the use of digital processing techniques that can handle the wide dynamic range (90 dB) required for simultaneous cancellation of both high-level linear interference and low-level non-linear interference, avoiding the need for complex analog techniques.
2Ease of manufacture
If conventional ADCs are used, then cost is reduced, but they cannot handle the high dynamic range required for digital cancellation
Solution Approach 1:
The patent segments the interference cancellation process into two distinct stages: linear interference cancellation and non-linear interference cancellation. By separating these functions, the system can use a moderate-resolution ADC for the initial sampling, then process linear components digitally, and finally handle non-linear components with a dedicated canceler. This segmentation allows the use of cost-effective ADCs while achieving the required 90 dB dynamic range through multi-stage processing.
Solution Approach 2:
The patent introduces a downconverter as an intermediary device between the RF input and the digital processing stages. This intermediary converts the high-frequency RF signal to baseband or intermediate frequency, enabling subsequent digital processing to achieve wide dynamic range cancellation without requiring expensive high-resolution ADCs capable of directly handling the full RF dynamic range.
3Device complexity
If a single-stage canceler is used, then device complexity is reduced, but it cannot effectively cancel both high-level linear and low-level non-linear interference
Solution Approach 1:
The patent divides the interference canceler into multiple functional stages: a downconverter for frequency translation, a linear interference canceler for removing linear components, and a non-linear interference canceler for removing non-linear artifacts. This segmentation of the single-stage design into specialized sub-stages enables effective cancellation across the full dynamic range while keeping each individual stage relatively simple.
Solution Approach 2:
The patent adds a frequency dimension to the cancellation process by introducing downconversion to baseband or intermediate frequency. This dimensional change transforms the problem from direct RF domain cancellation to a multi-dimensional approach involving frequency translation followed by digital processing, enabling separate handling of linear and non-linear interference components that would be difficult to separate in a single RF stage.
Data Source
AI summary
A multi-tier interference canceler includes a first canceler, a second canceler, and a third canceler. The first canceler samples radio frequency (RF) interference generated from a linear signal using a non-linear process. The RF interference includes linear interference and non-linear interference. The first canceler cancels the linear interference from the sampled RF interference based on the linear signal to produce a first non-linear interference sample. The second canceler receives an amplitude scaled, time-shifted version of the RF interference and cancels the linear interference from the received RF interference based on the linear signal to produce a second non-linear interference sample. The third canceler cancels the non-linear interference from the second non-linear interference sample using the first non-linear interference sample, to produce a receive signal that is substantially free of the non-linear interference and the linear interference.