Null Instruction Frame for BSS Channel Reservation
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Solution Overview
Problem
In wireless communication systems, especially in overlapping Basic Service Sets (BSSs), data collisions occur due to hidden stations and intense WLAN deployment, leading to unreliable transmissions.
Innovation Solution
A transmission control method and device that include a radio frame with a null instruction information domain to trigger an access point in another BSS to send a second radio frame indicating a channel reservation time, ensuring that other stations set their Network Allocation Vector (NAV) accordingly to avoid channel competition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple wireless stations share channels in overlapping BSSs, then channel utilization increases, but data collisions increase due to hidden stations
Solution Approach 1:
The patent applies preliminary action by having the first station send a first radio frame with a null data packet before actually transmitting data. This early frame reserves the channel and triggers access points in other BSSs to send CTS-TO-SELF frames, which set NAV values in listening stations. This preliminary reservation prevents hidden stations from causing collisions during the actual data transmission, thus improving transmission reliability while maintaining channel utilization.
2Area of stationary object
If access points in overlapping BSSs operate simultaneously, then network coverage expands, but data collisions occur due to hidden stations
Solution Approach 1:
The patent uses CTS-TO-SELF frames as intermediaries to coordinate channel access between overlapping BSSs. When an access point receives the first radio frame from a station in another BSS, it sends a CTS-TO-SELF frame back. This intermediary frame carries NAV information that listening stations use to set their virtual carrier sense, effectively mediating channel access and preventing collisions between hidden stations in different BSSs while allowing simultaneous network operation.
3Reliability
If virtual carrier sense is used to avoid hidden station problems, then channel reservation is improved, but NAV setting conflicts occur in overlapping BSSs
Solution Approach 1:
The patent applies local quality by making the NAV setting behavior dependent on the BSS context. Access points determine whether a received frame is from their own BSS or an overlapping BSS, and only respond with CTS-TO-SELF frames for frames from other BSSs. This localized differentiation allows each BSS to maintain its own NAV management independently while coordinating with overlapping BSSs, reducing unnecessary NAV updates and simplifying overall NAV management complexity.
Data Source
AI summary
Transmission control methods and devices for avoiding data collision are provided. According to the methods, a first radio frame is generated by a first station. The first radio frame includes a physical layer preamble, a null instruction information domain and a data section. The null instruction information domain is used for triggering an access point in another basic service set. The basic service set receives the first radio frame to send a second radio frame. The second radio frame indicates a time for reserving a channel. According to the methods, the first radio frame is sent by the first station.