NAV Update Logic for WLAN Hidden Node Resolution
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Solution Overview
Problem
In High Efficiency (HE) Wireless Local Area Networks (WLANs), existing Network Allocation Vector (NAV) techniques lead to inefficiencies due to difficulties in detecting all transmissions, especially in dense environments, causing performance degradation and hidden node problems.
Innovation Solution
A method is implemented by a station (STA) in a WLAN to update or disregard the NAV based on the duration indicated in a Physical Layer Protocol Data Unit (PPDU) and its association with the Basic Service Set (BSS), allowing for more accurate assessment of the wireless medium's availability and reducing unnecessary NAV updates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing NAV techniques are used in HE WLAN, then the network can maintain basic operation, but performance degradation occurs in dense environments due to hidden node problems and inability to detect all transmissions
Solution Approach 1:
The patent applies preliminary action by having stations update their NAV based on duration information from received PPDU preambles before actual transmissions occur. This allows stations to proactively reserve the wireless medium and avoid hidden node collisions by predicting future transmission durations from ongoing transmissions, even when those transmissions are not fully detectable by all stations.
2Reliability
If NAV is updated for every received PPDU, then the wireless medium reservation is maximized, but unnecessary NAV updates cause inefficiency and reduce channel utilization
Solution Approach 1:
The patent applies local quality by making NAV update behavior specific to different transmission scenarios. Stations selectively update NAV based on whether the received PPDU is from the same BSS or overlapping BSS, and whether it's a trigger frame or data frame. This localized differentiation ensures NAV updates only when necessary for collision avoidance, rather than universally for all transmissions.
Solution Approach 2:
The patent applies partial action by implementing selective NAV updates rather than updating for every received PPDU. Stations perform NAV updates only for specific conditions (same BSS transmissions, certain frame types), avoiding excessive NAV updates that would unnecessarily reserve the channel and reduce overall network efficiency.
3Reliability
If the STA updates NAV using duration from all received PPDU, then hidden node problems are reduced, but the complexity of NAV management increases
Solution Approach 1:
The patent applies segmentation by dividing NAV management into distinct cases: same BSS NAV updates, overlapping BSS NAV updates, trigger frame handling, and data frame handling. This segmentation simplifies the overall complexity by providing clear rules for each scenario rather than requiring complex global optimization algorithms.
Data Source
AI summary
A method implemented by a station (STA) in a Wireless Local Area Network (WLAN) to disregard a Network Allocation Vector (NAV) maintained by the STA. The method includes receiving a first frame from an Access Point (AP), determining whether the NAV maintained by the STA was previously set using a duration indicated in a second frame that (1) was received by the STA prior to receiving the first frame and (2) originated from the AP, and transmitting a third frame to the AP as an immediate response to the first frame without considering the NAV maintained by the STA when a determination is made that the NAV maintained by the STA was previously set using the duration indicated in the second frame that originated from the AP.