WLAN Power Saving Mode via Coordinated PS-Poll Transmission

Solution Overview

Problem

In wireless local area networks (WLANs), the power save mode mechanism is inefficient as stations (STAs) frequently transition between awake and doze states to manage pending frames, leading to increased power consumption and reduced network efficiency due to the lack of coordinated data transmission among multiple users.

Innovation Solution

The method involves an access point (AP) transmitting a beacon frame and a power saving (PS)-poll request frame to multiple target STAs, allowing them to send PS-poll frames on overlapped time resources, and subsequently transmitting downlink frames to those STAs based on the received PS-poll frames, utilizing techniques like UL MU OFDMA for efficient data transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If STAs frequently transition between awake and doze states to manage pending frames, then power consumption is reduced, but network efficiency deteriorates due to lack of coordinated data transmission

Engineering Contradiction:

Improvepower consumptionVSAvoidnetwork efficiency

Core Design Contradiction:

Use of energy by moving objectVSProductivity

Solution Approach 1:

The patent combines multiple STAs' PS-poll transmissions into a single uplink multi-user transmission opportunity using UL MU OFDMA. Instead of each STA individually transitioning to awake state to send PS-poll frames, the AP coordinates a joint transmission where multiple STAs send their PS-poll frames simultaneously on different frequency subcarriers, reducing the number of transitions needed while maintaining network efficiency

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The AP sends a PS-poll request frame in advance to notify multiple target STAs about upcoming uplink transmission opportunities. This preliminary action allows STAs to remain in doze state longer and wake up simultaneously for coordinated transmission, rather than individually transitioning to check for pending frames

Inventive Principle:

Principle #10Preliminary action

2Use of energy by moving object

If STAs operate in doze state for long time to reduce power consumption, then lifespan is increased, but frame transmission and reception become impossible

Engineering Contradiction:

Improvepower consumptionVSAvoidframe transmission capability

Core Design Contradiction:

Use of energy by moving objectVSEase of operation

Solution Approach 1:

The AP sends a PS-poll request frame in advance to notify multiple target STAs about upcoming uplink transmission opportunities. This preliminary action allows STAs to remain in doze state longer and wake up simultaneously for coordinated transmission, rather than individually transitioning to check for pending frames

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback through the TIM element in beacon frames and PS-poll request frames, which inform STAs about pending downlink frames and upcoming transmission opportunities. This feedback mechanism allows STAs to make informed decisions about when to transition from doze state, balancing power saving with transmission needs

Inventive Principle:

Principle #23Feedback

3Loss of information

If STAs periodically transition to awake mode to receive pending frame information, then information about buffered traffic is acquired, but power consumption increases

Engineering Contradiction:

Improveinformation about buffered trafficVSAvoidpower consumption

Core Design Contradiction:

Loss of informationVSUse of energy by moving object

Solution Approach 1:

The patent combines multiple STAs' PS-poll transmissions into a single uplink multi-user transmission opportunity using UL MU OFDMA. Instead of each STA individually transitioning to awake state to send PS-poll frames, the AP coordinates a joint transmission where multiple STAs send their PS-poll frames simultaneously on different frequency subcarriers, reducing the number of transitions needed while maintaining network efficiency

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The AP sends a PS-poll request frame in advance to notify multiple target STAs about upcoming uplink transmission opportunities. This preliminary action allows STAs to remain in doze state longer and wake up simultaneously for coordinated transmission, rather than individually transitioning to check for pending frames

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS10327204B2Method and apparatus for power saving mode operation in wireless LAN

Publication Date: 2019.06.18 LG ELECTRONICS INC

AI summary

A method and a corresponding apparatus, for a power saving mode operation in a wireless LAN, the method including: an AP transmitting, on the basis of a virtual bitmap of a TIM element comprised in a beacon frame, a PS-poll request frame to a plurality of target STAs that have received the indication of the existence of pended downlink data; the AP receiving, on overlapped time resources, each of a plurality of PS-poll frames from each of a plurality of PS-poll transmission STAs that are indicated on the basis of the PS-poll request frame among the plurality of target STAs; and the AP, on the overlapped time resources, transmitting each of a plurality of downlink frames to each of the plurality of PS-poll transmission STAs as a response to each of the plurality of PS-poll frames.