ER-PPDU Scrambler for Transmit Spectrum Mask Improvement
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Solution Overview
Problem
Range extension schemes in wireless communication networks result in a poorer transmit spectral mask margin due to repeated data symbols, which require operation in a more linear region, limiting the effectiveness of next-gen WLAN standards.
Innovation Solution
A method using a pseudo-random number (PN) sequence or scrambler is introduced to introduce randomness into repeated data symbols, improving the transmit spectral mask margin by applying a polarity sequence to subcarriers and modifying the Dual Carrier Modulation (DCM) pattern, and utilizing a scrambler or PN sequence at the modulated symbol level in the extended range physical layer protocol data unit (ER-PPDU) format.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If repeated data symbols are used for range extension, then wireless communication range is improved, but transmit spectral mask margin deteriorates
Solution Approach 1:
The patent applies polarity sequences (±1 multiplication) to repeated data symbols to modify their spectral characteristics. This parameter change transforms the deterministic repeated symbols into randomized versions, improving the spectral mask margin while preserving the range extension benefit. The polarity sequence is applied in the frequency domain before IFFT, changing the amplitude/phase parameters of the modulated symbols.
Solution Approach 2:
The patent introduces dynamic randomization by applying different polarity sequences to different repeated symbols. Instead of static repetition, the system dynamically varies the polarity of repeated symbols based on a pseudo-random sequence, which spreads the spectral energy more uniformly and improves the spectral mask margin.
2Manufacturing precision
If transmit power is operated in a more linear region to improve spectral mask, then spectral efficiency is improved, but power efficiency deteriorates
Solution Approach 1:
By applying polarity sequences to repeated symbols, the patent changes the spectral distribution parameters of the transmitted signal. This allows the system to maintain better spectral mask margins without requiring operation in a highly linear power region, thus preserving power efficiency while improving spectral characteristics.
Data Source
AI summary
A wireless communication system, apparatus, and methodology are described for enabling wireless communication devices to generate extended range Physical Layer Protocol Data Units (PPDUs) for wireless transmission to a destination communication devices by generating, at a first wireless communication device, a data sequence in which a plurality of repeated data symbols are encoded for wireless transmission to the second communication device, and then applying a scrambling sequence that is known to the first and second communication devices to the data sequence to generate an output data sequence wherein the plurality of repeated data symbols are pseudo-randomized prior to performing an inverse Fourier transform on the output data sequence.