WLAN PPDU Pilot Subcarrier Layout for CFO and Phase Noise
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Solution Overview
Problem
High-frequency wireless local area network (WLAN) communication faces challenges due to non-unified modulation schemes and incompatibility between low-frequency and high-frequency PPDU formats, leading to issues like carrier frequency offset (CFO) and phase noise, which current solutions fail to adequately address.
Innovation Solution
Increase the quantity of pilot subcarriers by adding M pilot subcarriers to the existing K pilot subcarriers, specifically allocating them at strategic locations within the subcarrier structure to enhance robustness against CFO and phase noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a low-frequency OFDM format PPDU with increased subcarrier spacing is used for high-frequency transmission, then compatibility with low-frequency format is improved, but the impact of carrier frequency offset and phase noise remains significant
Solution Approach 1:
The patent increases the subcarrier spacing parameter from conventional values (e.g., 78.125 kHz) to larger values (e.g., 156.25 kHz or 312.5 kHz) specifically for high-frequency transmission. This parameter change makes the system more adaptable to high-frequency characteristics while maintaining compatibility with low-frequency formats, and simultaneously reduces the relative impact of carrier frequency offset and phase noise on communication quality.
2Adaptability or versatility
If single-carrier transmission is performed first followed by OFDM transmission in a PPDU, then high-frequency transmission capability is achieved, but non-unified modulation schemes and format incompatibility occur
Solution Approach 1:
The patent designs a universal PPDU format that can be used for both low-frequency and high-frequency transmission. By making the low-frequency OFDM format adaptable to high-frequency scenarios through increased subcarrier spacing, the system eliminates the need for separate single-carrier and OFDM transmission schemes, achieving format unification and reducing system complexity while maintaining high-frequency capability.
3Reliability
If the subcarrier spacing is increased to resist carrier frequency offset and phase noise, then communication quality improves, but the bandwidth utilization efficiency may be reduced
Solution Approach 1:
The patent implements dynamic subcarrier spacing configuration where the spacing can be adjusted based on transmission conditions. For high-frequency transmission prone to CFO and phase noise, larger subcarrier spacing is applied; for conditions where efficiency is paramount, conventional spacing can be used. This dynamic approach allows the system to optimize between reliability and productivity based on actual transmission requirements.
Data Source
AI summary
This application provides a communication method and a communication apparatus. The method includes: generating a PPDU; and transmitting the PPDU on a channel corresponding to a first bandwidth. X subcarriers in Y subcarriers corresponding to the first bandwidth are used to carry data corresponding to X data subcarriers of at least one RU and/or at least one MRU, the X subcarriers are subcarriers other than K pilot subcarriers in the Y subcarriers, the Y subcarriers further include M pilot subcarriers, and the M pilot subcarriers are subcarriers other than the X subcarriers and the K pilot subcarriers in the Y subcarriers. The method is designed for “increasing a quantity of pilot subcarriers”, and the quantity of pilot subcarriers is extended from K to K+M. In other words, the M pilot subcarriers are added.