Wireless LAN Frame Transmission via Trigger Frames and EDCA
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Solution Overview
Problem
Next-generation WLAN systems face challenges in improving spectrum efficiency and area throughput, especially in dense environments with multiple access points and stations, and in outdoor settings, where existing technologies struggle to optimize performance under high user loads and interference.
Innovation Solution
The implementation of OFDMA technology and MU-MIMO techniques in wireless LAN systems, allowing multiple channels to be used simultaneously by multiple terminals without the limitations of the primary channel rule, and the use of trigger frames to allocate different frequency resources for uplink transmissions, along with enhanced distributed channel access (EDCA) procedures to manage channel access based on user priority levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If OFDMA and MU-MIMO techniques are implemented to allow multiple terminals to use multiple channels simultaneously, then spectrum efficiency and area throughput are improved, but device complexity and system configuration complexity increase
Solution Approach 1:
The patent segments the wireless medium into multiple orthogonal frequency subchannels (OFDMA) and spatial streams (MU-MIMO), allowing different terminals to occupy different segments simultaneously. This segmentation enables multiple users to transmit data in parallel without interfering with each other, thereby improving spectrum efficiency while managing system complexity through structured resource division.
Solution Approach 2:
The patent introduces frequency dimension (OFDMA) and spatial dimension (MU-MIMO) to the traditional time-division multiplexing approach. By utilizing these additional dimensions, the system can support multiple simultaneous transmissions without increasing temporal complexity, thus improving productivity while maintaining manageable device complexity.
2Productivity
If trigger frames are used to allocate frequency resources for uplink transmissions, then channel access efficiency is improved, but message length and processing overhead increase
Solution Approach 1:
The trigger frame performs preliminary resource allocation by assigning specific frequency resources to multiple terminals before their actual uplink transmissions. This preliminary action eliminates the need for individual contention-based access for each terminal, significantly improving channel access efficiency. The trigger frame contains pre-configured resource allocation information that terminals can directly execute.
Solution Approach 2:
The trigger frame serves multiple functions simultaneously: it acts as a scheduling command, a resource allocation message, and a synchronization signal. By consolidating these functions into a single frame structure, the patent reduces the overall control overhead compared to using separate frames for each function, thereby mitigating the message length increase.
3Productivity
If EDCA procedures are enhanced to manage channel access based on user priority levels, then fairness and throughput are improved, but device complexity increases
Solution Approach 1:
The patent applies different EDCA parameters (such as contention window sizes, arbitration interframe spaces) to different access categories or priority levels locally. High-priority traffic receives more favorable parameters while low-priority traffic uses less aggressive parameters. This local differentiation improves overall throughput and fairness without requiring complete redesign of the access control mechanism, thus managing device complexity effectively.
4Productivity
If multiple channels are used simultaneously by multiple terminals without primary channel rule limitations, then area throughput is improved, but interference management difficulty increases
Solution Approach 1:
The patent introduces the access point (AP) as an intermediary that coordinates uplink transmissions from multiple terminals. The AP sends trigger frames that schedule specific frequency resources for specific terminals, thereby mediating potential interferences. This intermediary approach enables simultaneous multi-channel access while the AP actively manages and prevents collisions, improving area throughput without overwhelming interference management complexity.
Data Source
Figure 1(A)~1(B)
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AI summary
A method for transmitting a frame in a wireless LAN system according to the present embodiment comprises: a step of determining whether to transmit a first frame to an AP through an EDCA by comparing a time parameter indicating the time used for transmission of a wireless terminal with a predetermined allowable time; a step of summing up, to the time parameter, a first required time for transmission of the first frame; a step of receiving, from the AP, a trigger frame for multi-user uplink transmission; and a step of performing data processing for a second frame transmitted in response to the trigger frame, wherein a second required time for transmission of the second frame is not summed up to the time parameter.