Remote Antenna RF Feedback Cancellation for Duplexer-Free Isolation

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Solution Overview

Problem

Conventional distributed antenna systems face challenges in efficiently isolating upstream and downstream radio frequency signals, leading to self-interference and increased costs due to the use of high-power duplexers, especially in multiple input/multiple output (MIMO) or antenna array applications.

Innovation Solution

The implementation of self-interference suppression processing using feedback signals derived from downstream radio frequency signals, combined with low-power duplexers or spatially isolated antennas, to reduce self-interference and eliminate the need for high-power duplexers, thereby enhancing signal isolation and reducing system size and cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high-power duplexers are used to isolate upstream and downstream RF signals, then signal isolation is improved, but system cost and device complexity increase

Engineering Contradiction:

Improvesignal isolationVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical/electrical isolation system (high-power duplexers) with a digital signal processing system. The self-interference suppression processing unit uses digital algorithms to cancel out self-interference in the upstream signal path, substituting complex hardware isolation with software-based interference cancellation. This reduces device complexity while maintaining signal isolation performance.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a feedback signal as an intermediary element. The downstream RF signal is tapped and processed to create a self-interference model, which then serves as a mediator to cancel the interference in the upstream path. This intermediary approach allows isolation without requiring direct physical separation or high-power duplexers.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-generated harmful factors

If high-power duplexers are used to suppress self-interference, then self-interference suppression is improved, but system cost increases

Engineering Contradiction:

Improveself-interference suppressionVSAvoidsystem cost

Core Design Contradiction:

Object-generated harmful factorsVSEase of manufacture

Solution Approach 1:

The patent substitutes expensive high-power duplexer hardware with more cost-effective digital signal processing components. The self-interference suppression is achieved through digital algorithms in the processing unit rather than through costly RF isolation hardware, significantly reducing system manufacturing cost while maintaining interference suppression effectiveness.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses lower-cost components (low-power duplexers or no duplexer at all) combined with digital processing to achieve the same functional result as expensive high-power duplexers. The system trades hardware cost for processing capability, using more affordable components that perform the isolation function through software rather than expensive hardware.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If high-power duplexers are used to isolate signals, then signal isolation is improved, but system size increases

Engineering Contradiction:

Improvesignal isolationVSAvoidsystem size

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The patent replaces bulky high-power duplexer hardware with compact digital signal processing units. The self-interference suppression processing is performed in the digital domain using standard processing components, which occupy significantly less physical space than the RF isolation hardware they replace, thereby reducing overall system size while maintaining isolation performance.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS10389313B2Distributed antenna system architectures

Publication Date: 2019.08.20 OUTDOOR WIRELESS NETWORKS LLC

AI summary

One embodiment is directed to a distributed antenna system comprising a host unit and at least one remote antenna unit that is communicatively coupled to the host unit. The host unit is configured to communicate a downstream transport signal from the host unit to the remote antenna unit. The remote antenna unit to which the downstream transport signal is communicated uses the downstream transport signal to generate a downstream radio frequency signal for radiation from an antenna associated with the remote antenna unit. The remote antenna unit is configured to communicate an upstream transport signal from the remote antenna unit to the host unit, wherein the upstream transport signal is generated from a received upstream radio frequency signal received at the remote antenna unit. The remote antenna unit is configured to perform self-interference suppression processing in an upstream signal path using, as an input thereto, a feedback signal derived from the downstream radio frequency signal radiated from the antenna. Other embodiments are disclosed.