Duplicated PPDU Phase Rotation for PAPR Reduction
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Solution Overview
Problem
High peak-to-average power ratio (PAPR) in OFDMA transmissions for IEEE 802.11be wireless communications leads to decreased signal-to-quantization noise ratio and power amplifier efficiency, particularly in lower power indoor bands, due to duplicated data sequences across wideband channels.
Innovation Solution
The method involves forming and transmitting duplicated physical layer convergence protocol (PPDU) units as sub-PPDUs on different sub-carriers with phase rotations, offsets, or ramps to mitigate PAPR, ensuring the same data content is carried across multiple sub-bands without exceeding signal limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If duplicated PPDU format is used in lower power indoor bands to boost power, then transmission power is increased, but peak-to-average power ratio increases causing signal levels to exceed permissible limits
Solution Approach 1:
The patent applies asymmetry by introducing different phase rotations to different subcarriers in the duplicated PPDU format. Specifically, odd-indexed subcarriers receive a phase rotation of π radians while even-indexed subcarriers receive no phase rotation, creating an asymmetric phase pattern that destroys the periodicity causing high PAPR while maintaining the power boosting benefit
Solution Approach 2:
The patent changes the phase parameter of subcarriers to mitigate PAPR. By applying phase rotations of either 0 or π radians to different subcarriers, the signal's temporal periodicity is altered, which reduces the peak-to-average power ratio while maintaining the duplicated format's power enhancement capability
2Productivity
If OFDMA transmissions use multiple subcarrier components added via IFFT, then data throughput is increased, but peak-to-average power ratio increases decreasing power amplifier efficiency
Solution Approach 1:
The patent introduces asymmetric phase rotations across subcarriers to break the constructive interference patterns that create high peaks in OFDMA signals. By rotating odd-indexed subcarriers by π radians while leaving even-indexed subcarriers unchanged, the signal distribution becomes more uniform, reducing PAPR and improving power amplifier efficiency while preserving multi-carrier throughput capabilities
Data Source
AI summary
Duplicated physical layer convergence protocol (PLCP) protocol data unit (PPDU) transmission is described for a wireless device with reduced peak-to-average power ratios (PAPR). One example includes obtaining a first sub-PPDU from ta PPDU that includes a data field with data content. A second sub-PPDU may also be obtained by duplicating the PPDU including the data content of the PPDU. At least one of a phase rotation, a phase offset, or a phase ramp is applied to at least a portion of a second set of sub-carrier of a wideband channel. The first sub-PPDU is transmitted on a first set of sub-carriers of the wideband channel and the second sub-PPDU is transmitted on the second set of sub-carriers of the wideband channel.