HE-LTF Symbol Alignment for Multi-User OFDMA Throughput
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Solution Overview
Problem
The IEEE 802.11n and 802.11ac standards do not effectively address the alignment of Long Training Field (LTF) symbols for users with different numbers of spatial streams in Orthogonal Frequency Division Multiple Access (OFDMA) symbols, leading to throughput and efficiency issues in wireless networks.
Innovation Solution
The proposed solution involves determining the highest number of spatial streams among users and generating High Efficiency-LTF (HE-LTF) symbols, with control circuitry adding padding symbols if necessary to align the symbols, using either random generation or circular repetition to ensure alignment, thereby ensuring that all users have the same number of HE-LTF symbols for efficient communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If LTF symbols are generated according to the number of spatial streams for each user, then the LTF symbols can be optimized for each user's specific needs, but the alignment of LTF symbols across users with different spatial streams is not addressed
Solution Approach 1:
The patent applies preliminary action by determining the maximum number of spatial streams among all users before generating LTF symbols. This allows the system to pre-establish the alignment requirement (N_HE-LTF ≥ maximum spatial streams) before actual symbol generation, ensuring that all users' LTF symbols can be aligned to the same length without requiring complex post-processing adjustments.
Solution Approach 2:
The patent applies local quality by allowing each user to have LTF symbols generated according to their specific number of spatial streams (local customization), while simultaneously applying a global alignment rule (padding to match the maximum) to ensure consistency across all users. This resolves the contradiction between user-specific optimization and system-wide alignment.
2Manufacturing precision
If padding symbols are added to align HE-LTF symbols across users, then symbol alignment is achieved, but the processing complexity increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the number of HE-LTF symbols based on the maximum spatial streams requirement. The alignment parameter N_HE-LTF is set to be greater than or equal to the maximum number of spatial streams, and padding symbols are added to each user's LTF sequence to match this parameter, achieving precise alignment through parameter standardization.
3Productivity
If the number of HE-LTF symbols is set based on the maximum spatial streams, then all users can be aligned, but users with fewer spatial streams require additional padding symbols
Solution Approach 1:
The patent applies partial or excessive action by generating LTF symbols at the maximum required level (excessive for users with fewer spatial streams) and then using padding to fill in the difference. This ensures that the system operates at optimal throughput by accommodating the maximum spatial streams requirement, while the padding operation is a simple time-domain extension that minimizes processing overhead.
Data Source
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AI summary
Aligning HE-LTFs corresponding to a plurality of users by determining a respective number of spatial streams corresponding to each user, determining a highest respective number of spatial streams of the spatial streams, and setting an alignment number of HE-LTF symbols to be equal to or larger than the highest respective number of spatial streams. For each respective user, padding symbols may be added to the respective generating matrix to yield a number of HE-LTF symbols in the respective matrix that corresponds to the alignment number.