Receiver AGC Thresholding for Narrowband Frequency Retuning

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Solution Overview

Problem

Conventional Automatic Gain Control (AGC) algorithms in radio receivers are inefficient due to the need for prolonged power measurements and frequent gain adjustments, leading to high power consumption and potential signal impairments, especially in scenarios where only a portion of the transmission bandwidth is received at a time.

Innovation Solution

Implementing a gain control system that assesses the frequency difference between current and target carrier frequencies to determine whether to perform a full or optimized AGC algorithm, using historical gain variability data and metrics like signal-to-noise ratio and channel coherence bandwidth to adjust amplifier gain settings efficiently.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional AGC algorithms perform full power measurements and frequent gain adjustments, then gain control reliability is improved, but power consumption increases and signal impairments occur

Engineering Contradiction:

Improvegain control reliabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent changes the parameters of AGC operation by detecting frequency differences between current and target carrier frequencies. When the frequency difference is below a threshold, the system switches to optimized AGC mode with different measurement and adjustment parameters, reducing power consumption while maintaining reliability. This is achieved by modifying the AGC algorithm's behavior based on frequency conditions rather than always performing full power measurements

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system performs preliminary frequency difference detection and assessment of historical gain variability data before executing the AGC algorithm. This preliminary action allows the system to determine in advance whether optimized AGC procedures can be used, avoiding unnecessary full power measurements and reducing power consumption while maintaining gain control reliability

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If conventional AGC algorithms perform full power measurements, then measurement precision is improved, but time consumption increases

Engineering Contradiction:

Improvepower measurement precisionVSAvoidtime consumption

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent modifies the measurement parameters based on frequency conditions. When frequency difference is small and historical data indicates stable gain characteristics, the system uses optimized measurement parameters that require less time while maintaining sufficient precision. This selective parameter adjustment resolves the contradiction between measurement precision and time consumption

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Instead of always performing complete full-bandwidth power measurements, the system applies partial measurements when frequency differences are small. The optimized AGC algorithm performs measurements only on relevant frequency portions, reducing time consumption while maintaining adequate measurement precision for the current operating conditions

Inventive Principle:

Principle #16Partial or excessive action

3Manufacturing precision

If AGC algorithms perform frequent gain adjustments, then gain control accuracy is improved, but signal impairments increase

Engineering Contradiction:

Improvegain control accuracyVSAvoidsignal impairments

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The system changes the gain adjustment parameters based on frequency conditions. When operating in optimized AGC mode with small frequency differences, the system uses adjusted gain values derived from historical data rather than frequent full adjustments. This reduces signal impairments while maintaining gain control accuracy through smarter parameter selection

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system uses historical gain variability data as feedback to determine appropriate gain adjustments. By analyzing past gain characteristics and frequency relationships, the optimized AGC algorithm can make more accurate adjustments with less frequency, reducing signal impairments from frequent gain changes while maintaining control accuracy

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS11239871B2Optimization of automatic gain control for narrow bandwidth operation

Publication Date: 2022.02.01 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

The gain of an amplifier in a receiver operating in a cellular communication system is controlled by determining one or more gain variability metrics, which are then used to produce first and second threshold values. A frequency difference between a current carrier frequency and a target carrier frequency is ascertained and then compared to the threshold values. Target gain setting production is based on comparison results: If the frequency difference is larger than the first threshold, a first automatic gain control algorithm is performed; if the frequency difference is smaller than the first threshold and larger than the second threshold, a second automatic gain control algorithm is performed, wherein the second automatic gain control algorithm uses a current gain setting as a starting point; and if the frequency difference is smaller than both the first and second thresholds, the current gain setting is used as the target gain setting.