Identifying Repeated PPDU Format via Extra Tone in 5.9 GHz WLAN
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Solution Overview
Problem
In the Next Generation Vehicular (NGV) standard, there is a need to distinguish between a repeatedly transmitted 11p PPDU format in wireless LAN systems, particularly for STAs supporting the 802.11bd standard, to enhance communication efficiency and support high-speed Dedicated Short Range Communication (DSRC) in the 5.9 GHz band.
Innovation Solution
A method where a receiving STA identifies a repeated PPDU format by receiving a first PPDU with extra tones and a second PPDU containing the same data, transmitted through a 5.9 GHz band with a frequency spacing of 156.25 kHz, allowing confirmation of scheduled transmissions and improving Signal-to-Noise Ratio (SNR).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If repeated PPDU transmission is used to improve SNR and communication reliability, then the ability to distinguish repeated PPDU format from standard PPDU format deteriorates
Solution Approach 1:
The patent applies the 'Color changes' principle by modifying the physical characteristics of the PPDU signal to indicate its format type. Specifically, repeated PPDUs include an extra tone at a defined frequency offset from the DC subcarrier, serving as a distinctive marker that allows receiving STAs to easily identify repeated PPDU format versus standard PPDU format, thus resolving the identification difficulty while maintaining SNR improvement benefits
Solution Approach 2:
The patent employs the 'Parameter changes' principle by altering the frequency domain parameters of the PPDU signal. The repeated PPDU format introduces an additional tone at a specific frequency offset, changing the spectral characteristics of the signal. This parameter modification enables reliable format identification without affecting the core repeated transmission mechanism that improves SNR
2Measurement precision
If extra tone is added to identify repeated PPDU format, then the complexity of signal processing increases
Solution Approach 1:
The patent applies the 'Taking out (Extraction)' principle by isolating the format identification function to a specific, easily detectable feature - the extra tone at a defined frequency offset. Instead of analyzing the entire signal structure, the receiving STA only needs to detect the presence or absence of this specific tone component, which simplifies the processing complexity while maintaining high identification accuracy
3Speed
If repeated PPDU transmission is implemented in 5.9 GHz band for V2X communication, then communication speed improves, but the compatibility with existing WLAN standards deteriorates
Solution Approach 1:
The patent employs the 'Dynamics' principle by creating a flexible PPDU format system that can adapt to different communication requirements. The repeated PPDU format with extra tone is designed as an extension that coexists with standard PPDU formats, allowing the system to dynamically select appropriate formats based on whether V2X high-speed communication or general WLAN compatibility is the priority, thus resolving the contradiction between speed improvement and standard compatibility
Data Source
AI summary
One example according to the present specification relates to a method for identifying the format of a PPDU in a wireless LAN (WLAN) system. A receiving STA may receive a first PPDU. The receiving STA may check at least one extra tone of at least one symbol of the first PPDU. The receiving STA may determine, on the basis of the at least one extra tone, the format of the first PPDU as a repeated PPDU format. Thereafter, the receiving STA may receive a second PPDU including the same data as the first PPDU.