Access Point NAV Update Logic for WLAN TXOP Continuity
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Solution Overview
Problem
In WLAN systems, the TXOP holder may fail to send data during the allocated TXOP period due to an updated NAV, leading to inefficiencies in spectrum resource utilization and communication quality.
Innovation Solution
The access point (AP) conditionally maintains or updates the NAV based on specific conditions, such as the duration of the received frame and the association of the transmitter address, to avoid unnecessary NAV updates, allowing continued data transmission during the TXOP period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the NAV is updated based on received frames during TXOP, then channel access control is improved, but data transmission continuity deteriorates
Solution Approach 1:
The patent applies dynamics by making the NAV update mechanism adaptive rather than static. The access point dynamically adjusts whether to update the NAV based on real-time conditions: if the received frame's duration exceeds the current NAV value and the frame is not addressed to the AP, then update NAV; otherwise, maintain the current NAV. This dynamic decision-making resolves the contradiction by allowing flexible channel access control while preserving data transmission continuity when appropriate.
Solution Approach 2:
The patent changes the parameter update behavior of NAV based on specific conditions. Instead of uniformly updating NAV for all received frames, the system selectively updates the NAV parameter only when certain criteria are met (duration comparison and address matching). This selective parameter change approach maintains reliability of channel control while avoiding unnecessary disruptions to ongoing data transmissions.
2Measurement precision
If the NAV is frequently updated, then channel sensing accuracy is improved, but spectrum resource utilization deteriorates
Solution Approach 1:
The patent applies partial action by selectively updating the NAV only when necessary, rather than updating it for every received frame. The condition check (duration comparison and address verification) ensures that NAV updates occur only when they provide genuine value for channel sensing accuracy. This partial update approach maintains measurement precision while avoiding excessive updates that would waste spectrum resources and reduce overall system efficiency.
3Reliability
If the access point sends RTS/CTS frames, then collision avoidance is improved, but transmission overhead increases
Solution Approach 1:
The patent applies preliminary action by using RTS/CTS frames to reserve the channel before actual data transmission. The access point sends RTS frames to potential recipients, and upon receiving CTS responses, secures the channel for subsequent data transfer. This preliminary channel reservation prevents collisions before they occur, improving reliability. Although it adds transmission overhead, the overhead is justified by the collision avoidance benefit in busy wireless environments.
Data Source
AI summary
A method includes an access point device that obtains a transmission opportunity (TXOP) in a wireless local area network (WLAN) and that allocates a first period in the TXOP to a non-access point device for data transmission. The access point device receives a first frame in the first period. An access address or a transmitter address of the first frame is associated with the non-access point device. The method further includes that the access point device keeps, based on the first frame, a network allocation vector (NAV) unchanged.