PPDU Transmission with Variable FFT Sizes
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Solution Overview
Problem
Next-generation wireless local area networks (WLANs) face challenges in improving spectrum efficiency and area throughput, especially in dense environments with multiple access points and stations, and require performance enhancements in both indoor and outdoor settings, including minimizing preamble overhead for backward compatibility with legacy stations.
Innovation Solution
A method and device for transmitting a physical layer convergence procedure (PLCP) protocol data unit (PPDU) with a first portion generated by inverse fast Fourier transform (IFFT) based on a first FFT size and a second portion generated by IFFT based on a different FFT size, allowing for efficient transmission and backward compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a uniform FFT size is used for the entire PPDU, then processing simplicity is maintained, but spectrum efficiency and area throughput cannot be improved in dense environments
Solution Approach 1:
The PPDU is divided into multiple portions, each processed with a different FFT size appropriate to its specific requirements. This segmentation allows optimized processing for different parts of the data unit without requiring complex processing for the entire PPDU, thereby improving spectrum efficiency while managing processing complexity.
Solution Approach 2:
The patent employs dynamic FFT size adjustment where different portions of the PPDU can use different FFT sizes based on their specific requirements. This dynamic approach allows the system to adapt processing parameters to actual needs, improving spectrum efficiency and area throughput in dense environments without requiring uniformly complex processing throughout.
2Productivity
If a new-format PPDU with different FFT sizes is used, then spectrum efficiency is improved, but backward compatibility with legacy stations is compromised
Solution Approach 1:
The PPDU structure is segmented into different portions that can be processed with different FFT sizes. This allows new-format PPDU to carry optimized data portions while maintaining compatibility mechanisms, enabling legacy stations to receive and process compatible portions while new stations benefit from the enhanced spectrum efficiency of the new format.
Solution Approach 2:
The patent designs the PPDU structure to serve multiple functions: it can operate in a legacy-compatible mode for backward compatibility while simultaneously supporting new-format portions for improved spectrum efficiency. This multi-functionality allows the same transmission mechanism to serve both legacy and next-generation requirements.
3Loss of substance
If legacy PPDU format is used, then backward compatibility is maintained, but preamble overhead cannot be minimized
Solution Approach 1:
The patent extracts and optimizes the preamble portion separately from the main data portions. By taking out the preamble overhead and processing it differently, the system can minimize preamble overhead while maintaining the necessary legacy support functionality in the extracted portion, thereby reducing overall overhead without sacrificing compatibility.
Solution Approach 2:
Instead of maintaining the traditional legacy PPDU structure throughout, the patent inverts the approach by using legacy-compatible portions only where necessary (such as preamble for legacy detection) while employing optimized structures for the remaining portions. This inversion allows minimal legacy support where required while achieving overhead reduction in the overall structure.
Data Source
AI summary
A method and a device for transmitting a data unit are disclosed. A method for transmitting a PPDU can comprise the steps of: generating, by an STA, the PPDU including a first portion and a second portion; and transmitting, by the STA, the PPDU, wherein the first portion is generated by performing IFFT according to a first FFT size, the second portion is generated by performing IFFT according to a second FFT size, and the first FFT size can differ from the second FFT size.