Wireless LAN Roaming Search Time Reduction via Frequency Separation

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Solution Overview

Problem

In wireless LAN systems, the time taken to search for alternative base stations during roaming is excessive, particularly affecting voice calls that require high real-time performance, as existing scanning methods like active and passive scanning waste time by using the same frequency for communication and search processes.

Innovation Solution

A wireless LAN system where the wireless terminal changes communication frequency to send probe requests to non-connected base stations through a wired LAN, allowing for simultaneous probe response messages to be sent via both wired and wireless channels, reducing search time by enabling the reception of signal level information without waiting for wireless probe responses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the wireless terminal uses the same frequency for communication and base station search, then the device complexity is reduced, but the search time increases significantly affecting voice call quality

Engineering Contradiction:

Improvefrequency management complexityVSAvoidbase station search time

Core Design Contradiction:

Device complexityVSLoss of time

Solution Approach 1:

The patent divides the frequency resources into separate search frequencies and communication frequencies. The wireless terminal performs base station searches on dedicated search frequencies that are different from the communication frequency, allowing simultaneous data transmission and base station scanning without interfering with each other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a frequency dimension separation where base station searches occur on different frequency channels than data communication. This dimensional separation allows the terminal to maintain communication on one frequency while searching for base stations on other frequencies, resolving the time conflict.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Ease of operation

If the wireless terminal performs active scanning by transmitting probe requests, then the search process becomes more controllable, but the communication delay increases due to frequency switching

Engineering Contradiction:

Improvesearch process controlVSAvoidcommunication delay

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The patent performs base station searches on alternative frequencies before roaming is actually needed. By proactively discovering and evaluating candidate base stations in advance, the terminal prepares roaming information that can be quickly utilized when communication quality degrades, avoiding last-minute frequency switching delays.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent enables continuous base station searching on search frequencies while maintaining uninterrupted data communication on communication frequencies. This continuous parallel operation ensures that base station information is always available without interrupting the ongoing communication process.

Inventive Principle:

Principle #20Continuity of useful action

3Measurement precision

If the wireless terminal waits for wireless probe responses during base station search, then the search accuracy is improved, but the search time increases which affects real-time voice calls

Engineering Contradiction:

Improvesignal level measurement accuracyVSAvoidsearch time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent uses the connected base station as an intermediary to deliver search results. Instead of waiting for direct wireless probe responses from target base stations, the terminal sends probe requests that are relayed through the connected base station, which then provides the search results including signal level information about alternative base stations through the existing communication channel.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the traditional wireless probe response mechanism with an information feedback mechanism through the connected base station. The search process substitutes direct wireless measurement waiting with indirect information acquisition through the already-established communication link, significantly reducing search time while maintaining accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS9942832B2Wireless LAN system and wireless communication device

Publication Date: 2018.04.10 JVC KENWOOD CORP

AI summary

A wireless terminal transmits a probe request message to a non-connected base station by changing the communication frequency from a first frequency to a second frequency used by the non-connected base station. The non-connected base station wirelessly sends a probe response message to the wireless terminal using the second frequency. The non-connected base station sends a probe redundant message to a connected base station by wire through a wired LAN. The connected base station wirelessly sends a probe redundant response message to the wireless terminal using the first frequency.