WLAN Channel Access Control After MU-to-SU Mode Switching
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Solution Overview
Problem
Existing wireless LAN systems face inefficiencies in channel access control during mode switching from MU to SU, leading to potential collisions and reduced throughput due to reset access control parameters and simultaneous restarts by terminals.
Innovation Solution
A communication apparatus and method that controls channel access by setting access control parameters like CW and BO in trigger frames, allowing terminals to adjust their waiting periods based on priority, number of transmissions, and retransmission needs, ensuring fair and efficient channel access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If access control parameters are reset when switching from MU mode to SU mode, then terminals can independently access the channel, but collisions occur and throughput decreases
Solution Approach 1:
The access point performs preliminary actions by setting transmission waiting periods in trigger frames before terminals switch to SU mode. This preliminary configuration of access control parameters prevents collisions by ensuring terminals have predetermined waiting periods established before they independently access the channel, resolving the contradiction between independent access and collision avoidance.
2Productivity
If all terminals restart channel access simultaneously after MU mode, then channel utilization increases, but collisions occur
Solution Approach 1:
The invention applies local quality by assigning different transmission waiting periods to different terminals through individual trigger frames. Instead of uniform restart behavior, each terminal receives customized access parameters tailored to its specific situation (new data vs. retransmission), enabling simultaneous channel access without collisions while maintaining high channel utilization.
Solution Approach 2:
The system dynamically adjusts access control parameters for each terminal based on real-time conditions. The access point determines appropriate transmission waiting periods considering each terminal's buffer status, retransmission needs, and priority levels, creating a dynamic parameter adjustment mechanism that prevents collisions while maximizing channel utilization during SU mode operation.
3Productivity
If transmission waiting period is shortened for retransmission terminals, then retransmission efficiency improves, but channel access conflicts increase
Solution Approach 1:
The access point acts as an intermediary that mediates channel access for retransmission terminals. By controlling and coordinating the transmission waiting periods of multiple terminals through trigger frames, the access point prevents direct conflicts between retransmission terminals while maintaining short waiting periods for efficiency. The intermediary manages the timing and sequence of retransmissions to avoid collisions.
4Device complexity
If uniform transmission waiting period is set for all terminals, then system simplicity is maintained, but fairness and efficiency decrease
Solution Approach 1:
The invention changes parameters by introducing differentiated transmission waiting periods based on terminal-specific conditions such as retransmission status, buffer content, and priority levels. Instead of uniform parameters, the system dynamically adjusts waiting periods to optimize channel access efficiency for each terminal while maintaining manageable complexity through centralized control by the access point.
Data Source
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AI summary
To provide a communication apparatus which controls channel access operation under a multi user environment, and a communication method. Channel access operation of each STA after an MU mode is finished is controlled through a trigger frame from an AP to prevent collision immediately after the MU mode is finished. Further, the AP sets a smaller CW upon transmission of the trigger frame than a CW of an STA to preferentially transmit the trigger frame and give priority to communication in the MU mode over communication in an SU mode. Further, by the CW of each STA upon switching of the mode being not reset, a transmission waiting period after the MU mode is finished is shortened.