OFDM PPDU Pilot Subcarrier Layout for High-Frequency WLAN
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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 physical layer protocol data units (PPDUs), leading to issues with carrier frequency offset (CFO) and phase noise, which are not adequately addressed by existing methods.
Innovation Solution
The solution involves increasing the number of pilot subcarriers in high-frequency transmission 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 resistance to CFO and phase noise remains insufficient
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 allows the low-frequency OFDM format to be adapted for high-frequency use while improving resistance to CFO and phase noise, as larger subcarrier spacing reduces the relative impact of frequency offsets and phase variations.
Solution Approach 2:
The patent introduces dynamic adjustment of transmission parameters based on frequency band. The system can switch between conventional subcarrier spacing for low-frequency bands and increased subcarrier spacing for high-frequency bands (60 GHz and above). This dynamic adaptation allows optimal performance in different frequency ranges while maintaining format compatibility where applicable.
2Ease of operation
If single-carrier transmission is performed first and then OFDM transmission in a PPDU at high frequency, then a unified modulation scheme is achieved, but robustness against high-frequency impairments deteriorates
Solution Approach 1:
The patent changes the fundamental parameter of subcarrier spacing to be larger than conventional values. This single parameter change enables the OFDM modulation to handle high-frequency impairments effectively while maintaining a unified OFDM-based modulation scheme throughout the PPDU, eliminating the need for single-carrier preambles followed by OFDM data portions.
Data Source
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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. This helps resist impact of a larger CFO and phase noise of a high frequency, improve robustness of low-frequency transmission, and improve communication quality.