Cellular-Assisted WLAN Channel Switch for Idle Mode Devices

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Solution Overview

Problem

In wireless local area networks (WLANs), user equipment in power save mode often misses channel switch announcements from access points (APs), leading to increased power consumption and time-consuming re-scanning processes when channel switching occurs, especially in densely populated areas with interference from nearby APs or radar signals.

Innovation Solution

A cellular-network-assisted WLAN channel switch announcement method, where the WLAN AP predicts user equipment wake-up times and maps user equipment IDs to be recognizable by the cellular network base station, allowing the base station to send channel switch announcements using RRC control signaling, ensuring timely notification of impending channel changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If user equipment enters power save mode to reduce power consumption, then power saving is improved, but channel switch announcement reception reliability deteriorates

Engineering Contradiction:

Improvepower consumptionVSAvoidchannel switch announcement reception reliability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent introduces the cellular network base station as an intermediary to forward channel switch announcements to sleeping user equipment. The base station receives announcements from WLAN APs and delivers them to user equipment through cellular signaling channels, enabling reliable delivery without requiring user equipment to wake up and listen to WLAN beacon frames.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent establishes a mapping relationship between user equipment identifiers in WLAN and cellular networks in advance. This preliminary action enables the base station to identify and contact the correct user equipment when channel switch announcements need to be delivered, ensuring timely notification even when user equipment is in power save mode.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If user equipment wakes up frequently to receive channel switch announcements, then announcement reception reliability is improved, but power consumption increases

Engineering Contradiction:

Improveannouncement reception reliabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The cellular network base station serves as a mediator that decouples the announcement delivery process from user equipment wake-up cycles. User equipment remains in power save mode while the base station handles announcement delivery through the cellular network, eliminating the need for frequent wake-ups.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical approach of user equipment actively listening to WLAN beacon frames with a signaling-based approach using the cellular network. This substitution allows announcements to be delivered through existing cellular control channels without requiring changes to user equipment power management behavior.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Speed

If channel switching is performed rapidly to avoid interference, then network responsiveness is improved, but user equipment synchronization deteriorates

Engineering Contradiction:

Improvechannel switching speedVSAvoiduser equipment synchronization

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The patent delivers channel switch announcements to user equipment in advance of the actual channel switching event. User equipment receives notification of the upcoming channel change and prepares accordingly, maintaining synchronization with the AP even when the switch occurs rapidly.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent establishes bidirectional communication between the base station and user equipment for channel switch announcements. The base station can send announcements to user equipment, and user equipment can provide feedback about its state, enabling coordinated channel switching that maintains network synchronization.

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP3331275B1Method for wireless local area network channel handover notification assisted by cellular network

Publication Date: 2020.04.15 SHANGHAI RES CENT FOR WIRELESS COMM

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AI summary

The present invention discloses a cellular-network-assisted wireless local area network (WLAN) channel switch announcement method, including the following steps: before a wireless network access point (AP) performs channel switching, delivering channel switch announcement signaling to correlated user equipment in a broadcast manner, and sending channel switch announcement request signaling to a cellular network base station that also serves the user equipment; after the cellular network base station receives the channel switch announcement request signaling, sending the channel switch announcement signaling to user equipment in an idle mode by using a cellular link air interface; and performing, by the WLAN AP, channel switching within a predetermined time, and following, by user equipment that directly acquires channel switch information by receiving the channel switch announcement signaling and user equipment that acquires channel switch information by using the cellular network base station, the WLAN AP and performing channel switching.