Multi-Link NAV Control for Wireless LAN Collision Prevention
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Solution Overview
Problem
In wireless LAN systems, the hidden node problem occurs when a station has a hidden relationship with another station, leading to collisions during flexible downlink/uplink transmissions, as existing methods do not effectively prevent collisions by setting a network allocation vector (NAV) across multiple links.
Innovation Solution
A method where a transmitting station sets a NAV for a second link by transmitting a frame including NAV information to a first receiving station through a different link, while receiving a signal from a second receiving station, to prevent collisions and ensure efficient data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transmitting STA uses a single channel to transmit one packet, then the transmission is simple and straightforward, but collision prevention is limited and cannot address hidden node problems in multi-link environments
Solution Approach 1:
The patent extends the traditional single-link NAV mechanism into a multi-dimensional multi-link environment. The transmitting STA sets NAV values for multiple links simultaneously, and the receiving STA must manage NAV settings across different link dimensions. This dimensional extension allows collision prevention to work effectively in multi-link hidden node scenarios by reserving channels across multiple links, not just one.
Solution Approach 2:
The patent segments the NAV setting process into link-specific components. Each link has its own NAV value that can be independently set and managed. The frame structure is segmented to include link-specific NAV information for each link, allowing granular control over channel reservation on a per-link basis rather than a monolithic approach.
2Reliability
If the transmitting STA transmits NAV information for the second link through the first link while receiving from the second link, then collision probability is reduced, but the transmission process becomes more complex
Solution Approach 1:
The patent uses the first link as an intermediary channel to convey NAV information about the second link. By transmitting NAV settings through a different link than the one being monitored, the system creates an indirect communication path that allows the receiving STA to be warned about upcoming transmissions on the second link without interfering with the current reception process. This intermediary approach resolves the operational complexity of simultaneous transmission and reception.
3Loss of information
If NAV information is included in the PHY header, then all STAs within coverage receive the information, but the transmission overhead increases
Solution Approach 1:
The patent applies local quality by allowing flexible placement of NAV information in different frame portions depending on the specific communication scenario. NAV information can be placed in the PHY header for broad dissemination, or in the MAC header for targeted delivery to specific STAs. This localized approach allows the system to optimize information dissemination based on whether broad awareness or targeted notification is needed, reducing unnecessary overhead.
4Reliability
If the transmitting STA monitors only one channel at a time, then the reception process is simple, but hidden node collisions cannot be prevented
Solution Approach 1:
The patent uses preliminary action by having the transmitting STA set NAV values in advance on links where it will transmit later. The receiving STA receives these preliminary NAV settings through other links before the actual transmission occurs on the monitored link. This advance notification allows the receiving STA to prepare by setting its own NAV, preventing hidden node collisions without requiring simultaneous multi-channel monitoring.
Data Source
AI summary
One embodiment according to the present specification relates to a method for transmitting, from a first link, information for setting a NAV in a second link. When transmission STA performs communication through a second link, the transmission STA can transmit, through a first link, information for setting the NAV for the second link in another STA. Particularly, the transmission STA can receive, from the second reception STA, a second frame through the second link. The transmission STA can transmit, to a first reception STA, a first frame through the first link during the reception of the second frame. The first frame can include information for setting the NAV for the second link. The first reception STA can set the NAV for the second link on the basis of the first frame.