Active Scanning for Wireless Local Area Networks

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Solution Overview

Problem

Battery-powered client devices in wireless local area networks (WLANs) face power consumption challenges during connectivity sequences, which can significantly reduce battery life due to the need to maintain radio activity for extended periods while scanning for and connecting to access points.

Innovation Solution

Implementing an active scanning method that allows client devices to quickly identify and connect to wireless networks by transmitting probe requests on multiple channels without waiting for beacon frames, enabling faster discovery of access points and reducing power consumption by transitioning to a sleep state when no matching networks are found.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If client devices use traditional passive scanning waiting for beacon frames, then power consumption is reduced during scanning, but network discovery time increases significantly

Engineering Contradiction:

Improvenetwork discovery timeVSAvoidpower consumption

Core Design Contradiction:

Loss of timeVSUse of energy by moving object

Solution Approach 1:

The patent implements active scanning where client devices proactively transmit probe requests to access points before formally connecting to the network. This preliminary action of sending probe requests allows clients to discover networks faster without waiting for beacon frames, resolving the contradiction between fast discovery and power consumption by performing the discovery action in advance of formal connection

Inventive Principle:

Principle #10Preliminary action

2Reliability

If client devices maintain radio activity for extended periods to ensure reliable network connection, then connection reliability improves, but battery life decreases

Engineering Contradiction:

Improveconnection reliabilityVSAvoidbattery life

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent implements a structured connectivity sequence with periodic phases: active scanning phase where probe requests are sent, followed by authentication phase, then association phase. This periodic structure allows the radio to be actively engaged only during necessary phases rather than continuously, maintaining connection reliability while reducing overall power consumption and extending battery life

Inventive Principle:

Principle #19Periodic action

3Productivity

If client devices perform active scanning on multiple channels, then network discovery speed increases, but power consumption during scanning increases

Engineering Contradiction:

Improvenetwork discovery speedVSAvoidscanning power consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent performs active scanning on multiple channels as a preliminary action before formal network connection. By completing the scanning phase quickly across multiple channels and then transitioning to authentication and association phases, the system achieves fast network discovery while limiting the duration of high-power scanning activity, thus balancing productivity gains with power consumption management

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS7912465B2Scanning for wireless local area networks

Publication Date: 2011.03.22 MALIKIE INNOVATIONS LTD

AI summary

In a wireless device, active scanning for a particular wireless network name is initiated during passive scanning for a wireless network that matches a profile stored in a wireless local area network controller, the profile including the particular wireless network name. Active scanning for the particular wireless network name includes transmitting one or more probe requests, each transmitted on a different communication channel.