Transmit Channel Response Estimation Using Frequency Shifting

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Solution Overview

Problem

In transmission systems, the feedback channel response is inadvertently included in the error correction signal, leading to incomplete compensation for the transmission channel response, resulting in an output signal that is improperly modified by the feedback channel.

Innovation Solution

A system and method that learns and identifies the feedback channel response and transmission channel response in real-time by shifting the frequency of feedback and transmission signals, allowing for the calculation of both responses using singular value decomposition, and generates a control signal to modify the input signal by the inverse of the transmission channel response, thereby eliminating the feedback channel response from the pre-distortion circuit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the adaptation engine uses the feedback channel to measure the transmission channel response, then the system can determine the transmission channel response for current operating conditions, but the feedback channel response is inadvertently included in the error correction signal, leading to incomplete compensation for the transmission channel response

Engineering Contradiction:

Improvereal-time channel response measurement capabilityVSAvoidaccuracy of transmission channel response identification

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent segments the composite system response into two distinct components: transmission channel response and feedback channel response. By introducing frequency offsets to the feedback channel, the patent enables separate identification of each channel's response characteristics through singular value decomposition, allowing the adaptation engine to extract only the transmission channel response for pre-distortion correction.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces frequency offsets as an intermediary mechanism to differentiate between the transmission channel and feedback channel responses. This frequency offset acts as a marker that allows the system to distinguish and separate the two channel responses mathematically, enabling accurate identification of the transmission channel response without contamination from the feedback channel.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If the system uses external monitoring equipment to measure the transmission channel response, then the measurement accuracy is high, but the system cannot operate outside production or test environments

Engineering Contradiction:

Improvetransmission channel response measurement accuracyVSAvoidoperational environment flexibility

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent enables the system to perform its own channel response measurement and characterization using its internal feedback channel and signal processing capabilities. The adaptation engine uses singular value decomposition to self-identify the transmission channel response from the composite system response, eliminating the need for external monitoring equipment and enabling operation in real-world deployment environments.

Inventive Principle:

Principle #25Self-service

3Device complexity

If the feedback channel response is not eliminated from the pre-distortion correction, then the system structure remains simple, but the output signal is improperly modified by the feedback channel

Engineering Contradiction:

Improvepre-distortion circuit structure simplicityVSAvoidoutput signal accuracy

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent replaces physical modifications to the feedback channel structure with a mathematical signal processing approach. Instead of adding hardware components to physically separate or eliminate the feedback channel response, the patent uses singular value decomposition and frequency offset techniques to mathematically identify and remove the feedback channel response from the composite system response, maintaining structural simplicity while improving output signal accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS8306150B2System and method for estimating a transmit channel response and/or a feedback channel response using frequency shifting

Publication Date: 2012.11.06 TEXAS INSTRUMENTS INC

AI summary

Systems and methods for identifying a transmission channel response and a feedback channel response from a plurality of composite system responses are disclosed. A plurality of shifted feedback signals are created by shifting a feedback signal frequency by a plurality of first offset values and/or by shifting a transmission signal frequency by a plurality of second offset values. The feedback signals are compared to an input signal to identify the transmission channel response and/or a feedback channel response. A control signal is generated for a pre-distortion circuit to modify the input signal by an inverse of the transmission channel response. The composite system response is measured at a plurality of operating frequencies and at the plurality of offset values. The measurements are stored in a matrix and singular value decomposition is applied to the matrix of measurements to calculate the transmission channel response and feedback channel response.