Wireless LAN Symbol Boundary Alignment in A-PPDU
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Solution Overview
Problem
In the context of next-generation WLAN systems, particularly the IEEE 802.11be or EHT WLAN system, there is a need to improve the alignment of symbol boundaries between High Efficiency (HE) PPDU and Extreme High Throughput (EHT) PPDU within an Aggregated-PPDU (A-PPDU) to prevent interference and ensure efficient communication.
Innovation Solution
The method involves aligning the symbol boundaries of each field in the HE PPDU and EHT PPDU by setting the type and maximum number of spatial streams, ensuring that the lengths of specific fields such as L-STF, L-LTF, L-SIG, RL-SIG, HE-SIG-A, HE-STF, HE-LTF, and EHT-SIG are identical, with padding used to maintain alignment, and configuring HE-STF and EHT-STF based on 1× or 2× periods depending on downlink or uplink transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If HE PPDU and EHT PPDU are transmitted with different symbol boundary alignments, then backward compatibility with 802.11ax is maintained, but interference occurs at symbol boundaries between different PPDU types
Solution Approach 1:
The patent applies preliminary action by pre-configuring the symbol boundary alignment through setting the type and maximum number of spatial streams before transmission. The transmitting station determines the appropriate alignment configuration in advance and applies padding or adjusts field lengths to ensure symbol boundaries are aligned, preventing interference before it occurs. This is evident in the method where the transmitter configures HE-STF and EHT-STF based on 1× or 2× periods and uses padding to maintain alignment.
Solution Approach 2:
The patent employs parameter changes by modifying the lengths of specific fields (L-STF, L-LTF, L-SIG, RL-SIG, HE-SIG-A, HE-STF, HE-LTF, EHT-SIG) and adjusting the number of spatial streams to achieve symbol boundary alignment. The transmitting station changes parameters such as the period configuration (1× or 2×) for HE-STF and EHT-STF, and applies padding to adjust field lengths, thereby transforming the transmission parameters to ensure aligned symbol boundaries while maintaining backward compatibility.
2Reliability
If the lengths of all fields in HE PPDU and EHT PPDU are made identical through padding, then symbol boundary alignment is achieved, but transmission efficiency decreases due to additional padding overhead
Solution Approach 1:
The patent applies local quality by applying padding selectively only to specific fields that require alignment (such as L-STF, L-LTF, L-SIG, RL-SIG, HE-SIG-A, HE-STF, HE-LTF, EHT-SIG) rather than uniformly padding the entire PPDU structure. This localized approach ensures symbol boundary alignment where necessary while minimizing the overall padding overhead and preserving transmission efficiency in other parts of the data structure.
Solution Approach 2:
The patent uses partial action by aligning only the critical preamble fields and signal fields that require synchronization, rather than making all fields identical in length. The method configures HE-STF and EHT-STF based on 1× or 2× periods and applies padding selectively to achieve alignment for the essential synchronization and signaling portions, accepting that not all fields need identical lengths, thus balancing reliability with transmission efficiency.
3Productivity
If the number of spatial streams is increased to support EHT requirements, then throughput is improved, but complexity of signaling and coordination increases
Solution Approach 1:
The patent applies universality by designing a unified symbol boundary alignment mechanism that works across different PPDU types (HE PPDU and EHT PPDU) and different numbers of spatial streams. The same alignment principles and field configurations can be applied regardless of whether 1, 2, 4, or 8 spatial streams are used, reducing the need for separate signaling mechanisms for each configuration and simplifying the overall system complexity while supporting high throughput.
Data Source
AI summary
The present disclosure proposes a method and apparatus for aligning symbol boundaries of each field of an HE PPDU and an EHT PPDU within an A-PPDU in a wireless LAN system. In particular, a reception STA receives the A-PPDU from a transmission STA. The reception STA decodes the A-PPDU. The A-PPDU comprises an HE PPDU for a primary 160 MHz channel and an EHT PPDU for a secondary 160 MHz channel. The length from a first L-STF to an HE-SIG-A is the same as the length from a second L-STF to a U-SIG. Symbol boundaries of an HE-SIG-B and an EHT-SIG are equally aligned.