Selective Observation Receiver for Transmitter Noise Cancellation
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Solution Overview
Problem
Existing RF transmitter-receiver systems face challenges in reducing transmitter noise leakage without the need for additional receiver circuitry, especially in multi-transmitter-receiver systems, where the cost and size of larger duplexers and additional circuitry become impractical as devices shrink and become less expensive.
Innovation Solution
A system with a plurality of transmitter outputs and receivers, including an observation receiver to estimate transmission noise and a cancellation filter to cancel the estimated noise in receiver paths, allowing for selective coupling of transmitter paths to an observation path for noise cancellation, reducing the need for additional receiver circuitry by using a single observation path to estimate noise for multiple transmitters.
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 transmit noise correlates with received signal patterns and uses this harmful correlation to generate cancellation signals. By analyzing the relationship between transmitted signals and their leaked counterparts in the receive path, the system creates adaptive filters that exploit this very correlation to subtract and eliminate the noise leakage, converting the harmful effect into a useful reference for cancellation.
Solution Approach 2:
The patent introduces asymmetric processing where the transmit path undergoes digital predistortion while the receive path applies adaptive noise cancellation. The system treats the transmit and receive paths differently by implementing separate signal processing chains, with the receive path using reference signals from the transmit path to generate asymmetric cancellation signals that specifically target the leaked noise without affecting the desired receive signal.
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 introduces an intermediary digital signal processing system that acts as a virtual isolator between transmit and receive paths. Instead of relying solely on physical isolation components like large duplexers, the system uses adaptive filters and cancellation signals as intermediaries to electronically remove transmit noise leakage from the receive path, achieving isolation without the physical footprint of larger RF components.
Solution Approach 2:
The patent replaces mechanical/physical isolation mechanisms (large duplexers with physical separation) with digital signal processing mechanisms. By using adaptive noise cancellation algorithms that operate in the digital domain, the system achieves transmit-receive isolation without requiring large physical components, substituting electronic intelligence for mechanical separation.
3Object-generated harmful factors
If additional receiver circuitry is added to generate estimates of leakage noise for each transmitter-receiver pair, then transmitter noise cancellation is improved, but device complexity and cost increase
Solution Approach 1:
The patent implements a universal noise cancellation architecture where a single observation receiver performs the function of estimating noise for multiple transmitter-receiver pairs. Instead of dedicating separate observation receivers to each pair, the system uses one multi-functional observation receiver that can selectively monitor and generate cancellation signals for different transmit paths, reducing the overall number of required components while maintaining comprehensive noise cancellation coverage.
Solution Approach 2:
The patent merges the functions of multiple potential observation receivers into a single shared observation receiver. By combining the noise estimation functionality for all transmitter-receiver pairs into one unit, the system reduces component count and complexity. The single observation receiver is equipped with the capability to handle multiple transmit signals and generate appropriate cancellation signals for each, consolidating what would otherwise require separate dedicated circuits.
Data Source
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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.