Tone Rotation Selection for Lower-PAPR Wi-Fi Preambles
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Solution Overview
Problem
The IEEE 802.11be standard's pre-EHT modulated fields in wireless communication systems result in high peak to average power ratio (PAPR) due to repetitive structures in the frequency domain, which can be exacerbated by dynamic multi-user OFDMA scenarios with preamble puncturing, leading to inefficient power usage.
Innovation Solution
An access point and station employ a processing device to identify puncturing patterns and compute tone rotation patterns using parameters to minimize PAPR by selecting an optimal tone rotation pattern based on the puncturing pattern for the channel width, utilizing a selection matrix and projection vectors to reduce PAPR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pre-EHT modulated fields are used with repetitive frequency domain structures, then wireless communication compatibility is maintained, but peak to average power ratio (PAPR) increases
Solution Approach 1:
The patent applies parameter changes by modifying the frequency domain structure through tone rotation. Specifically, it changes the phase parameters of subcarriers in the pre-EHT modulated fields using rotation angles (e.g., π/4, π/2, 3π/4) to transform the repetitive frequency domain structure into a non-repetitive time domain structure, thereby reducing PAPR while maintaining compatibility
Solution Approach 2:
The patent implements dynamics by making the tone rotation pattern adaptive rather than fixed. The system dynamically selects different rotation patterns based on detection results and channel conditions, allowing the modulation structure to change adaptively to minimize PAPR for different transmission scenarios while preserving compatibility with pre-EHT standards
2Productivity
If dynamic multi-user OFDMA scenarios with preamble puncturing are implemented, then user flexibility and spectral efficiency improve, but PAPR is exacerbated
Solution Approach 1:
The patent applies preliminary action by performing tone rotation on the pre-EHT modulated fields before transmission. The system pre-processes the signal by applying rotation patterns to the frequency domain data, which prevents PAPR exacerbation from occurring during the actual OFDMA transmission with puncturing, thereby maintaining both spectral efficiency and power efficiency
Solution Approach 2:
The patent implements local quality by applying different rotation patterns to different portions of the frequency spectrum. Specifically, it applies tone rotation selectively to the pre-EHT modulated fields (L-STF, L-LTF, L-SIG, RL-SIG) while leaving other portions unchanged, thereby locally optimizing power efficiency in the affected bands without impacting overall spectral efficiency
Data Source
AI summary
An access point may include a processing device configured to: identify a puncturing pattern for a channel width of a physical layer protocol data unit (PPDU) of a transmit signal; compute one or more tone rotation patterns using one or more tone rotation pattern parameters; and select a tone rotation pattern of the one or more tone rotation patterns based on the puncturing pattern for the channel width to minimize a peak to average power ratio (PAPR) of the transmit signal. The access point may include a transceiver configured to transmit the transmit signal to a wireless device based on the tone rotation pattern.