Distributed Antenna Feedback Architecture for RF Self-Interference
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Solution Overview
Problem
Conventional distributed antenna systems face challenges in efficiently isolating downstream and upstream 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 digital signal processing techniques, to reduce self-interference and potentially eliminate the need for high-power duplexers by using low-power duplexers or spatially isolated antennas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If high-power duplexers are used to isolate downstream and upstream RF signals, then signal isolation is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical/electrical isolation system (high-power duplexer) with a digital signal processing system. The self-interference cancellation is achieved through digital subtraction of the estimated self-interference signal from the received upstream signal, eliminating the need for complex physical isolation components.
Solution Approach 2:
The patent introduces an intermediary processing stage between the antenna and the baseband processing. A self-interference estimator and canceller are inserted in the signal path to actively compensate for self-interference, serving as a mediator that removes the harmful effect without requiring complete physical isolation.
2Object-affected harmful factors
If high-power duplexers are used to isolate downstream and upstream RF signals, then signal isolation is improved, but cost increases
Solution Approach 1:
The patent replaces expensive, power-intensive high-power duplexer hardware with computationally-intensive but cheaper digital signal processing algorithms. The implementation uses standard baseband processing units to perform self-interference cancellation, significantly reducing hardware cost and power consumption.
Solution Approach 2:
The patent substitutes costly mechanical/electrical isolation components with software-based digital signal processing. The self-interference cancellation is performed through mathematical operations on the digital signal, eliminating the need for expensive RF isolation hardware.
3Object-affected harmful factors
If spatially isolated antennas are used for downstream and upstream signals, then self-interference is reduced, but system complexity and space requirements increase
Solution Approach 1:
The patent replaces physical spatial separation with digital signal processing. Instead of requiring physically separated transmit and receive antennas, the system uses a single antenna array with digital self-interference cancellation algorithms to achieve the same isolation effect, dramatically reducing space requirements.
Solution Approach 2:
The patent moves the isolation problem from the spatial domain to the digital signal processing domain. By processing signals in the digital domain after reception, the system achieves isolation without requiring spatial separation of antennas, effectively solving the problem in a different dimension.
Data Source
AI summary
Communication system includes first unit; and second unit(s) having processing unit(s), downstream signal path(s), and upstream signal path(s). First unit communicates downstream digital transport signal (including digital representation of original downstream RF signal received at first unit) to second unit(s). Second unit uses processing unit and downstream signal path to generate downstream RF signal (for radiation from antenna) from downstream digital transport signal; and communicates upstream digital transport signal (generated from upstream RF signal received at second unit(s) using processing unit(s) and upstream signal path(s)) to first unit. Upstream digital transport signal includes digital representation of received upstream RF signal. Feedback path digitizes downstream RF signal(s) to provide digital representation(s) of downstream RF signal radiated from antenna to processing unit(s). Second unit pre-distorts input signal to downstream signal path for non-linearities in downstream signal path using digital representation of downstream RF signal radiated from antenna as received from feedback path.