PS-Poll Triggering in Wireless LAN for Dense Environments
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Solution Overview
Problem
Next-generation wireless local area networks (WLANs) face challenges in improving spectrum efficiency and area throughput, especially in dense environments with multiple access points and stations, and require enhanced performance in outdoor and indoor settings, including scenarios like smart homes and stadiums, where existing WLANs are inadequate.
Innovation Solution
The method involves triggering multiple PS-poll frames by access points to facilitate downlink multi-user transmission, utilizing orthogonal frequency division multiple access (OFDMA) and multi-user multiple input multiple output (MU MIMO) technologies to efficiently manage data transmission and reception across multiple stations, improving power saving mechanisms and channel access techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional single-user transmission is used in WLAN, then device compatibility is maintained, but spectrum efficiency and area throughput are insufficient in dense environments
Solution Approach 1:
The patent segments the transmission medium by introducing orthogonal frequency division multiple access (OFDMA) that divides the frequency spectrum into multiple subcarriers, and multi-user multiple input multiple output (MU-MIMO) that separates spatial streams. This allows multiple stations to transmit simultaneously on different frequency resources and spatial layers, thereby improving spectrum efficiency and area throughput in dense WLAN environments while maintaining compatibility with traditional single-user transmission modes.
2Use of energy by moving object
If power saving mode is implemented in WLAN stations, then energy consumption is reduced, but channel access efficiency deteriorates due to periodic wake-up requirements
Solution Approach 1:
The patent implements a feedback mechanism where the access point monitors the buffer status of each station and actively triggers power-saving mode transitions. When the AP determines that a station has no pending data to transmit, it sends a trigger frame to put the station into power-saving mode. The station wakes up only when triggered by the AP, eliminating the need for periodic wake-ups and reducing both power consumption and channel access delays. This feedback-based approach allows the system to dynamically adjust power saving behavior based on actual traffic conditions.
3Productivity
If multiple stations transmit simultaneously in dense WLAN environments, then area throughput increases, but interference and collision probability increase
Solution Approach 1:
The patent applies local quality by assigning different orthogonal resource characteristics to different stations: OFDMA allocates specific frequency subcarriers to specific stations, while MU-MIMO assigns specific spatial layers and beamforming directions. This localized resource allocation ensures that each station's transmission is confined to its designated resources, minimizing interference with other stations. The orthogonal nature of these resources maintains high transmission reliability even when multiple stations transmit simultaneously, thereby increasing area throughput without sacrificing reliability.
Data Source
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AI summary
Method and apparatus for triggering a plurality of PS-poll frames in wireless LAN is disclosed. The method for triggering a plurality of PS-poll frames is comprising receiving, by a station, STA, a beacon frame including transmission time offset information from an access point, AP, wherein the transmission time offset information includes information on a time point at which the STA entering a doze state after reception of the beacon frame is to be switched to an awake state; receiving, by the STA, a power save, PS,-poll trigger frame based on the transmission time offset information from the AP, wherein the first PS-poll trigger frame triggers uplink multi-user, UL-MU, transmission from a plurality of STAs including the STA, wherein the PS-poll trigger frame includes partial association identifier, AID, information for the plurality of STAs and UL MU resource allocation information for a plurality of PS-poll frames to be transmitted by the plurality of STAs; and transmitting, by the STA, a PS-poll frame to the AP in response to the PS-poll trigger frame.