STF Sequence Phase Rotation for 320 MHz WLAN PAPR
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Solution Overview
Problem
Current WLAN systems face challenges in efficiently transmitting Physical Protocol Data Units (PPDUs) over wideband channels, particularly in achieving optimized Peak to Average Power Ratio (PAPR) for high-throughput applications like the emerging IEEE 802.11be standard.
Innovation Solution
The proposed solution involves configuring an optimized Short Training Field (STF) sequence for wideband channels, specifically for the 320 MHz band, by applying phase rotation to a repeated STF sequence based on the 80 MHz band defined in the 802.11ax standard. This approach ensures compatibility and efficiency across different bandwidths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the existing 802.11ax STF sequence is used for wideband channels, then backward compatibility is maintained, but the PAPR is not optimized for wideband transmission
Solution Approach 1:
The wideband STF sequence is segmented into multiple 80 MHz sub-sequences, each corresponding to a specific 80 MHz band. By segmenting the overall wideband sequence into manageable parts that match the existing 802.11ax definitions, the patent achieves both PAPR optimization for the entire wideband while maintaining compatibility with existing 80 MHz receivers that only process their respective band.
Solution Approach 2:
The patent merges multiple 80 MHz STF sequences (defined in 802.11ax) to form a composite wideband STF sequence. This combining approach allows the system to leverage existing standardized sequences while achieving optimized PAPR characteristics across the aggregated wideband spectrum, resolving the contradiction between compatibility and optimization.
2Productivity
If a new wideband STF sequence is designed for optimized PAPR, then transmission efficiency improves, but compatibility with existing 802.11ax systems deteriorates
Solution Approach 1:
The patent applies local quality by ensuring that each 80 MHz portion of the wideband STF sequence maintains the exact properties of the original 802.11ax STF sequence. This local preservation of sequence characteristics ensures that 802.11ax systems can process their band without issues, while the global structure achieves optimized PAPR for wideband transmission, thus improving productivity without sacrificing compatibility.
3Device complexity
If the STF sequence is repeated across wideband, then sequence structure is simplified, but PAPR optimization is insufficient
Solution Approach 1:
Instead of simple repetition which creates symmetry and suboptimal PAPR, the patent introduces asymmetric phase rotation factors across different 80 MHz bands. This asymmetric modification breaks the simple repetition pattern while maintaining structural simplicity, achieving both low complexity and optimized PAPR performance by carefully designing the phase rotation parameters.
Solution Approach 2:
The patent changes the phase parameters of the repeated STF sequence by applying different phase rotation factors to different 80 MHz bands. This parameter modification transforms the simple repeated structure into an optimized wideband sequence with improved PAPR characteristics, resolving the contradiction between structural simplicity and performance optimization.
Data Source
AI summary
A method and a device for receiving a PPDU in a wireless LAN system are presented. 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 an STF signal. The STF signal is generated on the basis of a first STF sequence for a broadband. The first STF sequence is a sequence of which a phase rotation is applied to a sequence in which a second STF sequence is repeated. The second STF sequence is an STF sequence for a 80 MHz band defined in an 802.11ax wireless LAN system. If the broadband is a 320 MHz band, the first SFT sequence is a sequence in which preset sequence M is repeated, and is defined to be the same as {M 1 −M 0 −M 1 −M 0 M 1 −M 0 −M 1 −M 0 −M −1 M 0 M −1 M 0 −M −1 M 0 M −1 M}*(1+j)/sqrt(2)).