HE-LTF Cyclic Prefix Extension for WLAN AGC Estimation
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Solution Overview
Problem
Current automatic gain control (AGC) methods in wireless local area networks (WLANs) require large system overheads due to the use of legacy short and high throughput short training fields, which can be reduced by employing a high efficiency long training field with a cyclic prefix (CP) that allows for accurate AGC estimation while minimizing intersymbol interference.
Innovation Solution
The implementation of a high efficiency long training field with a CP length sufficient for AGC estimation in wireless local area networks, where the CP of the first symbol is extended to ensure accurate AGC estimation and reduce system overheads, allowing for a shorter preamble length and reduced energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If legacy short training field and high throughput short training field are used for AGC estimation, then AGC estimation can be performed, but system overheads are relatively large
Solution Approach 1:
The patent merges the AGC estimation function with the high efficiency long training field (HE-LTF) by extending the cyclic prefix of the first HE-LTF symbol. This combines the functions of channel estimation and AGC estimation into a single field, eliminating the need for separate AGC training fields and reducing overall system overhead while maintaining AGC estimation accuracy.
Solution Approach 2:
The extended cyclic prefix of the first HE-LTF symbol serves multiple functions: it provides channel estimation capability, enables AGC estimation, and maintains compatibility with existing HE-LTF processing. This multi-functional design reduces the total number of training fields required in the preamble.
2Measurement precision
If cyclic prefix length is extended for AGC estimation, then AGC estimation accuracy improves, but preamble length increases
Solution Approach 1:
The patent combines AGC estimation functionality with the existing HE-LTF structure by extending its cyclic prefix, rather than adding a separate AGC training field. This merging approach provides the necessary extended duration for accurate AGC estimation without proportionally increasing overall preamble length, as the HE-LTF itself is already part of the mandatory preamble structure.
Data Source
AI summary
Embodiments disclose an automatic gain control method and a communications device in a wireless local area network. The method includes generating a physical layer packet, where the physical layer packet includes a high efficiency long training field, the high efficiency long training field includes N symbols, a length of a cyclic prefix (CP— of a first symbol in the N symbols is greater than or equal to a minimum length required by a receiver device to perform automatic gain control (AGC) estimation, and N is a positive integer. The method also includes sending the physical layer packet to the receiver device.