APPDU Padding for IEEE 802.11ax Sub-PPDU Alignment
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Solution Overview
Problem
In wireless local area networks (WLANs), the existing IEEE 802.11 standards face challenges in aligning packet ends of multiple sub-PPDUs transmitted through different subchannels, leading to inefficiencies in packet decoding and acknowledgement feedback, particularly in dense environments with increased interference.
Innovation Solution
The proposed solution involves padding methods for aggregated physical layer protocol data units (APPDUs) to align the packet ends of sub-PPDUs across different subchannels, using techniques such as pre-FEC, post-FEC padding, and packet extension (PE) fields, ensuring consistent tone spacing and proper preamble design for orthogonality and efficient transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple sub-PPDUs are transmitted through different subchannels without padding alignment, then transmission flexibility is improved, but packet decoding efficiency deteriorates due to misaligned packet ends
Solution Approach 1:
The patent applies preliminary action by calculating and adding padding bytes to sub-PPDUs before transmission to align their packet ends. The access point determines the required padding length based on the longest sub-PPDU and adds pre-FEC and post-FEC padding bytes accordingly, ensuring all sub-PPDUs are aligned before being transmitted through different subchannels. This preliminary alignment resolves the contradiction by maintaining transmission flexibility while ensuring efficient packet decoding.
2Productivity
If padding is added to align packet ends of sub-PPDUs, then decoding efficiency is improved, but transmission time increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the padding length based on the specific transmission scenario. The access point calculates the exact number of padding bytes needed for each sub-PPDU to achieve alignment, rather than using fixed padding. This allows optimization of the padding amount to minimize transmission time while still achieving the alignment necessary for efficient decoding.
3Manufacturing precision
If pre-FEC and post-FEC padding are applied to all sub-PPDUs, then packet end alignment is improved, but overhead increases
Solution Approach 1:
The patent applies local quality by selectively applying different padding strategies to different sub-PPDUs based on their individual characteristics and requirements. Rather than uniformly applying the same padding to all sub-PPDUs, the access point determines the appropriate padding approach for each sub-PPDU, optimizing the balance between alignment precision and overhead reduction for each local case.
Data Source
AI summary
A method is described for aligning high efficiency (HE), extremely high throughput (EHT), and EHT+sub-physical layer protocol data units (sub-PPDUs) included in an aggregated PPDU (APPDU) trigger frame. The method includes aligning a preamble portion of the sub-PPDUs by applying a multi-user PPDU (MU-PPDU) format to each of the sub-PPDUs and aligning a data portion of the sub-PPDUs by including a padding subfield in each of the sub-PPDUs to produce a common length.