PPDU Signal Extension Field for WLAN Processing Delay
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Solution Overview
Problem
The increased data processing time at the receive end in WLANs with 4x symbol length leads to processing delays, particularly in high-bandwidth scenarios, causing issues with completing data processing and state switching within the current SIFS duration of 16 us.
Innovation Solution
The introduction of a frame extension or signal extension field after the last OFDM symbol, which includes padding bits not involved in encoding or decoding, provides additional time for data processing, and the use of indication mechanisms in the HE-SIG to inform the receive end when to stop decoding, optimizing processing time without increasing overhead significantly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If 4x symbol length is introduced to improve transmission efficiency, then data transmission capacity is improved, but data processing time at the receive end increases
Solution Approach 1:
The patent segments the OFDM symbol structure by introducing a signal extension field that separates the data payload from the processing requirement indicators. This allows the receive end to identify and stop decoding at optimal points without processing the entire extended symbol, thus resolving the contradiction between increased transmission capacity and excessive processing time.
Solution Approach 2:
The patent applies preliminary action by embedding indication information in the HE-SIG field before the data payload, which pre-informs the receive end about the decoding stop position. This allows the receive end to prepare and execute stopping at the precise moment, avoiding unnecessary processing of padding bits and maintaining efficiency despite the 4x symbol length extension.
2Productivity
If 4x symbol length is used to increase data volume per symbol, then transmission efficiency is improved, but SIFS duration becomes insufficient for processing and state switching
Solution Approach 1:
The indication information is placed in advance in the HE-SIG field, allowing the receive end to know the exact decoding stop position before actual data processing begins. This preliminary information enables the receive end to complete processing within the constrained SIFS duration by avoiding unnecessary decoding of padding bits that would otherwise extend the processing time beyond 16 us.
Solution Approach 2:
The patent changes the parameter structure by introducing a new indication field that modifies how the receive end interprets the symbol length and decoding requirements. This parameter change allows the system to maintain the 4x symbol length for high data volume while simultaneously enabling the receive end to adjust its processing duration to fit within SIFS constraints.
3Quantity of substance
If padding bits are added to extend symbol length, then data capacity is improved, but decoding complexity increases
Solution Approach 1:
The patent extracts the padding bits from the decoding process by providing explicit indication information about the decoding stop position. The receive end takes out only the necessary data portion for decoding and ignores the padding bits, thus increasing data capacity without proportionally increasing decoding complexity.
Solution Approach 2:
By preliminarily indicating the decoding stop position in the HE-SIG field, the patent enables the receive end to know in advance where to stop decoding. This preliminary action prevents the receive end from unnecessarily processing padding bits, thereby maintaining decoding complexity at acceptable levels while still utilizing the extended symbol length for increased data capacity.
Data Source
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AI summary
Embodiments of the present invention provide a physical layer protocol data unit PPDU transmission method, including: generating and sending a PPDU, where the PPDU includes a signal extension SE field, the SE field is after the last orthogonal frequency division multiplexing OFDM symbol that carries useful information, the PPDU includes indication information, the indication information is in a high efficiency signaling field HE-SIG, and the indication information I is generated based on a symbol length of the SE field and is used to indicate whether a receive end needs to adjust a calculated quantity of OFDM symbols.