Collocated Transceiver Interference Cancellation via Analog Signal Injection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Interference issues arise in RF communication systems due to collocated transceivers and overlapping antenna patterns, leading to reduced quality of service and capacity in wireless networks, especially in backhaul links where antennas are in close proximity and share the same or adjacent frequency bands.
Innovation Solution
A method to cancel interference by acquiring the interfering signal and generating an analog or digital cancellation signal, which is then injected into the receiver to reduce interference, using techniques such as cross-correlation and adaptive filtering, and employing multiple input multiple output (MIMO) antennas configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If collocated transceivers use the same frequency band for simultaneous transmission and reception, then spectral efficiency is improved, but self-interference occurs reducing signal quality
Solution Approach 1:
The system applies preliminary anti-action by generating an analog cancellation signal that is the inverse of the expected self-interference signal before it corrupts the received signal. The cancellation signal is injected into the receiver path to preemptively neutralize the interference, allowing simultaneous transmission and reception on the same frequency without degradation of signal quality.
Solution Approach 2:
An intermediate cancellation signal is introduced as a mediator between the transmitted signal and the received signal. This cancellation signal, generated from a sample of the transmitted signal and processed through adaptive filtering, acts as a intermediary element that subtracts the self-interference component from the received signal, enabling full-duplex operation.
2Volume of moving object
If transmitting and receiving antennas are placed in close proximity, then device compactness is improved, but mutual interference between antennas increases
Solution Approach 1:
The system replaces mechanical isolation methods (such as physical separation or shielding) with an electronic signal processing approach. Instead of mechanically isolating the antennas through distance or barriers, the invention uses analog signal cancellation and adaptive digital filtering to electronically remove the mutual interference, maintaining compact antenna placement while eliminating interference.
Solution Approach 2:
The system dynamically changes signal parameters through adaptive filtering, adjusting the cancellation signal's amplitude and phase to match the interfering signal characteristics. By continuously adapting the cancellation parameters based on the transmitted signal sample and received signal feedback, the system maintains effective interference cancellation despite the close proximity of antennas.
3Productivity
If strong interfering signals are present in the same spectrum block, then frequency utilization is improved, but receiver front end saturation occurs
Solution Approach 1:
The system performs preliminary action by generating and injecting the cancellation signal before the interfering signal reaches the receiver front end in a way that would cause saturation. By subtracting the interfering signal component in the analog domain, the cancellation occurs upstream of the low-noise amplifier, preventing the strong interfering signal from saturating the receiver front end circuitry.
Solution Approach 2:
The cancellation signal acts as a beforehand cushioning mechanism that protects the receiver front end from saturation. By preemptively removing the strong interfering signal component through analog cancellation, the system cushions the receiver front end against the harmful effects of strong signals, allowing high frequency utilization without risking saturation.
4Object-affected harmful factors
If analog cancellation signal is injected into receiver, then interference reduction is improved, but system complexity increases
Solution Approach 1:
The system merges the interference cancellation function with the existing receiver architecture by integrating the analog cancellation signal injection into the receiver's signal path. The cancellation signal is combined with the received signal through a summing junction that is part of the receiver structure, consolidating multiple functions (signal reception, interference cancellation, and processing) into a unified system rather than adding separate independent subsystems.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 2C
AI summary
The present invention, in some embodiments thereof, relates to a method of cancelling interference in a wireless system, wherein the interference introduced by an interfering signal causing reception of an interfered signal responsive to transmission of a desired signal, the method comprising acquiring the interfering signal from a transmitter during or before transmission thereof, generating an analog cancellation signal based on the acquired interfering signal, and injecting said analog cancellation signal into an interfered receiver receiving said interfered signal to reduce said interference therefrom.