Observation Receiver Switching for Multi-Transmitter Noise Cancellation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing radio frequency (RF) transmitter-receiver systems face challenges in reducing transmitter noise leakage without adding additional receiver circuitry, especially in multi-transmitter-receiver systems, where the cost and size of larger duplexers become impractical as devices shrink and become less expensive.
Innovation Solution
A system with a selectively coupled observation receiver that estimates transmission noise and applies a cancellation filter to reduce noise leakage, using a single observation path to serve multiple transmitter-receiver pairs, and selectively coupling transmitters to the observation path based on monitored communication conditions to optimize noise cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If digital predistortion techniques are used to generate more usable power from amplifiers, then power efficiency is improved, but transmitter noise leakage into received signals increases
Solution Approach 1:
The patent observes that transmitter noise leakage correlates with the transmitted signal and uses this harmful correlation to generate a noise estimate. By processing the transmitted signal through the receiver chain to create an estimate of the leakage noise, and then subtracting this estimate from the received signal, the system converts the harmful noise into a useful reference for cancellation, thereby maintaining power efficiency while reducing noise interference
Solution Approach 2:
The patent combines multiple signal processing techniques including digital predistortion for power efficiency with transmit noise cancellation for noise reduction. By integrating these composite approaches - using both the predistorted transmitted signal and the received signal processing - the system achieves both improved power efficiency and reduced noise leakage simultaneously
2Object-generated harmful factors
If the size of the duplexer is increased to achieve better isolation between transmit and receive bands, then transmitter noise leakage is reduced, but device size and cost increase
Solution Approach 1:
The patent replaces the mechanical/physical solution of using larger duplexers for noise isolation with a signal processing solution. Instead of increasing physical isolation hardware, the system uses digital signal processing to estimate and subtract transmitter noise from received signals, thereby reducing device size and cost while maintaining noise reduction performance
Solution Approach 2:
The patent changes the approach from physical parameter changes (increasing duplexer size) to signal parameter processing. By manipulating signal parameters through estimation and subtraction in the digital domain, the system achieves noise reduction without changing physical hardware dimensions, thus reducing device size and cost
3Object-generated harmful factors
If additional receiver circuitry is added to generate noise estimates for each transmitter-receiver pair in multi-transmitter systems, then transmitter noise cancellation is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes the receiver circuitry universal by enabling a single receiver to handle multiple transmitter-receiver pairs through signal processing. Instead of requiring dedicated noise estimation circuitry for each transmitter pair, the system uses the existing receiver to process signals from multiple transmitters, applying noise cancellation algorithms that work across all pairs, thereby reducing device complexity while maintaining effective noise cancellation
Solution Approach 2:
The patent creates a virtual copy of the noise estimation process through signal processing rather than physical circuit duplication. By processing the transmitted signal through the receiver chain to generate a noise estimate, the system creates a software/digital copy of the noise characteristics without requiring additional physical receiver circuitry, thus reducing complexity while achieving noise cancellation
Data Source
AI summary
In a multi transmitter-receiver system, transmitter noise cancellation may be applied selectively for certain transmitters by exploiting asymmetries of the system. Hence, observation receiver(s) numbering less than the number of transmitters may be provided saving space and cost. Each observation receiver may selectively couple to a transmitter path and estimate the leakage noise from that transmitter. Based on the estimated leakage noise, noise cancellation may be applied to corresponding receiver path(s). Selection of the transmitters for leakage estimation may be based on system conditions at that time, which may be known to the system or may be estimated dynamically.