Uplink Trigger Frame Synchronization in HE WLAN
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Solution Overview
Problem
Current WLAN systems lack a specified method for uplink channel access, particularly in High Efficiency WLAN (HEW) environments with dense deployments of Access Points (APs) and overlapping coverage areas, which hinders performance improvements felt by users despite increased bandwidth and peak transmission rates.
Innovation Solution
A method and apparatus for uplink channel access in HEW, where a station (STA) receives a trigger frame from an Access Point (AP) to transmit an uplink frame, including padding for synchronized transmissions among multiple STAs, ensuring all transmissions end at the same time indicated by the trigger frame, and the AP responds after a predetermined time following the end of the uplink transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple STAs transmit uplink frames simultaneously in dense WLAN deployments, then network capacity and user experience are improved, but transmission synchronization and collision avoidance become problematic
Solution Approach 1:
The AP sends a trigger frame before the uplink transmission to preliminarily establish the transmission parameters, timing, and synchronization requirements for all STAs. This preliminary action ensures that all STAs are prepared and synchronized before actually transmitting, resolving the synchronization problem while maintaining high network capacity
Solution Approach 2:
The system implements a feedback mechanism where the AP monitors the uplink transmissions from multiple STAs and provides responses (such as block acknowledgments) to indicate successful reception. This feedback allows the system to detect and correct synchronization issues, ensuring reliable simultaneous transmissions while maintaining high network capacity
2Productivity
If uplink transmissions from multiple STAs are synchronized to end at the same time, then channel access efficiency is improved, but the complexity of timing coordination increases
Solution Approach 1:
The trigger frame serves multiple functions simultaneously: it schedules the uplink transmission, specifies the timing parameters, indicates the target end time for all transmissions, and provides resource allocation information. This multi-functionality simplifies the overall timing coordination complexity while maintaining high channel access efficiency
Solution Approach 2:
The AP acts as an intermediary that centralizes the timing coordination function. Instead of requiring complex peer-to-peer synchronization between multiple STAs, the AP mediates the timing by providing a common reference point (the trigger frame) that all STAs use to align their transmissions, thereby reducing overall system complexity while improving channel access efficiency
Data Source
AI summary
The present disclosure relates to a method and apparatus for uplink channel access in a High Efficiency WLAN (HEW). According to one aspect, a method for transmitting an uplink frame by a station (STA) to an access point (AP) in a wireless local area network may be provided. The method may include receiving from the AP a trigger frame for eliciting an uplink transmission from the STA, transmitting to the AP the uplink frame according to a type of the trigger frame, wherein when the uplink frame is transmitted in an uplink multiple user (MU) transmission, the uplink frame includes a padding added by the STA such that transmissions from a plurality of STAs including the STA in the uplink MU transmission end at a same time indicated by the trigger frame, and receiving from the AP a frame in response to the uplink MU transmission a predetermined time after an end of the uplink MU transmission.