Broadband WLAN PPDU Preamble Phase Rotation for Lower PAPR
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Solution Overview
Problem
The increased number of spatial streams in new WLAN standards, such as IEEE 802.11be (EHT), requires improved signaling techniques to optimize the peak-to-average power ratio (PAPR) for enhanced PPDU transmission in broadband channels, particularly in 240 MHz or 320 MHz bands.
Innovation Solution
A method and apparatus for setting a phase rotation value applied to a legacy preamble for optimized PAPR in L-STF and L-LTF, with 80 MHz-based preamble puncturing, to enhance subcarrier efficiency and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of spatial streams is increased in new WLAN standards, then the throughput and data rate are improved, but the peak-to-average power ratio (PAPR) increases causing transmission inefficiency
Solution Approach 1:
The patent applies phase rotation parameter changes to the legacy preamble signals (L-STF and L-LTF) to optimize the PAPR. By adjusting the phase rotation values applied to different spatial streams, the patent reduces the peak power while maintaining the same throughput, thereby improving power efficiency and reducing energy loss in broadband transmissions (240 MHz and 320 MHz bands).
2Productivity
If broadband transmission (240 MHz or 320 MHz) is used, then the subcarrier efficiency and throughput are improved, but the PAPR optimization becomes more difficult due to preamble puncturing
Solution Approach 1:
The patent applies different phase rotation values to different parts of the legacy preamble (L-STF and L-LTF) based on the specific broadband configuration and puncturing pattern. This localized optimization approach allows the system to maintain high subcarrier efficiency in 240 MHz and 320 MHz bands while simplifying PAPR optimization by treating each preamble component with appropriate phase adjustments rather than requiring complex global optimization.
3Adaptability or versatility
If legacy preamble is used in broadband, then backward compatibility is maintained, but the PAPR is not optimized leading to transmission inefficiency
Solution Approach 1:
The patent modifies the phase rotation parameters of the legacy preamble while keeping the overall structure and format unchanged. This allows backward compatibility to be maintained as legacy devices can still recognize and process the preamble, while the phase rotation optimization reduces PAPR and improves transmission efficiency in broadband (240 MHz and 320 MHz) environments.
Data Source
Figure 1(a)~1(b)
Figure 2
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AI summary
Proposed are a method and an apparatus for receiving a PPDU in a wireless LAN system. Specifically, a reception STA receives a PPDU from a transmission STA through a broadband and decodes the PPDU. The broadband is a 320 MHz band or a 160+160 MHz band. The PPDU includes a first field and a second field. The first field includes an L-STF and an L-LTF. The first field is generated on the basis of a first phase rotation value. The first phase rotation value is generated on the basis of a second phase rotation value and a third phase rotation value. The second phase rotation value is obtained by repeating a phase rotation value for a 160 MHz band, defined in an 802.11 ax wireless LAN system.