WLAN Receiver AGC Switching for Low-Power Listen Mode

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Solution Overview

Problem

WLAN devices spend significant power due to continuous automatic gain control (AGC) operations during listen mode, which involves continuous sensing and computation of in-phase and quadrature components of the received signal.

Innovation Solution

Implementing a receiver with a first and second power estimator, where one estimator is inactive during listen mode, using single-rail power estimation to conserve power, and switching to IQ power estimation upon detecting a frame.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If both in-phase and quadrature power estimators are operated continuously during listen mode, then accurate AGC can be maintained, but power consumption increases significantly

Engineering Contradiction:

ImproveAGC accuracyVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The power estimation function is segmented into two separate estimators (in-phase and quadrature), allowing selective operation. During listen mode, only one estimator is activated while the other is deactivated, reducing power consumption. When a frame is detected, both estimators are activated to ensure accurate AGC processing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically switches between different operational states: during listen mode, only one power estimator is active; upon frame detection, the system transitions to activate both estimators. This dynamic adaptation allows the system to optimize power consumption based on operational requirements while maintaining AGC accuracy when needed.

Inventive Principle:

Principle #15Dynamics

2Use of energy by moving object

If single-rail power estimation is used during listen mode, then power consumption is reduced, but measurement capability is limited

Engineering Contradiction:

Improvepower consumptionVSAvoidpower estimation accuracy

Core Design Contradiction:

Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The system performs preliminary power estimation using a single active estimator during listen mode to detect frame arrivals. This preliminary action consumes minimal power while providing sufficient capability for frame detection. Upon frame detection, the system then activates the second estimator to perform more comprehensive power estimation for accurate AGC processing.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The measurement capability is dynamically adjusted based on operational mode. During listen mode, the system uses single-rail estimation with one active estimator to reduce power consumption. When a frame is detected, the system transitions to IQ power estimation with both estimators active, thereby dynamically scaling measurement precision to match operational requirements.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS20250357957A1Automatic gain control in a wireless local area network receiver

Publication Date: 2025.11.20 AVAGO TECHNOLOGIES INTERNATIONAL SALES PTE LTD

AI summary

An example receiver includes: a first power estimator operable to receive an in-phase signal; a second power estimator operable to receive a quadrature signal; a combiner coupled to outputs of the first and second power estimators, the combiner having an output that supplies estimated signal power; and an automatic gain controller coupled to the output of the combiner, the automatic gain controller operable to, in a first mode, turn off one of the first or second power estimators such that the one of the first or second power estimators is an inactive power estimator and the other is an active power estimator, and control the combiner to generate the estimated signal power using a function of an output of active power estimator.