Frequency Reference Signal Weighting for Fading-Resistant Synchronization
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Solution Overview
Problem
Existing communication systems face challenges in achieving accurate frequency synchronization due to the impact of frequency selective fading on frequency offset correction, particularly when using frequency shift keying (FSK) or on-off keying (OOK) signals, as current frequency offset correction methods do not adequately address this issue.
Innovation Solution
A communication method and apparatus that employs a frequency reference signal with non-uniform energy distribution across frequency domain units, concentrating energy on specific units to mitigate the effects of frequency selective fading, allowing for improved frequency synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency offset correction is performed using traditional frequency reference signals with uniform energy distribution, then frequency synchronization can be achieved, but frequency selective fading significantly degrades the correction accuracy
Solution Approach 1:
The patent applies local quality by creating non-uniform energy distribution across frequency domain units, where specific units (N out of M) are assigned higher energy weights. This concentrates the frequency reference signal energy on selected subcarriers, making those specific frequency components more robust against frequency selective fading. The weighted distribution ensures that at least some high-energy units fall within the passband, enabling accurate frequency offset correction despite channel conditions.
Solution Approach 2:
The patent changes the energy distribution parameter of the frequency reference signal from uniform to non-uniform. By adjusting the energy weights of different frequency domain units according to a specific pattern (where N units have higher energy than the remaining M-N units), the system adapts the reference signal characteristics to better withstand frequency selective fading effects, thereby improving frequency synchronization accuracy.
2Object-affected harmful factors
If frequency reference signal energy is concentrated on fewer frequency domain units, then frequency selective fading impact is reduced, but signal robustness may decrease
Solution Approach 1:
The patent segments the frequency domain units into two groups: N units with higher energy weights and M-N units with lower energy weights. This segmentation allows the system to concentrate energy on selected units to combat frequency selective fading, while the remaining units provide additional redundancy and robustness. The segmented structure ensures that even if some high-energy units are affected by fading, the system maintains reliability through the distributed nature of the segments.
Data Source
AI summary
This application provides a communication method and a communication apparatus. The method provides a solution that can mitigate impact of frequency selective fading on frequency offset correction. Specifically, a network device sends, to a terminal device by using M subcarriers, a frequency reference signal generated by the network device, where a ratio of a sum of energy of the frequency reference signal carried by N subcarriers in the M subcarriers to total energy of the frequency reference signal is not equal to a ratio of N to M, N<M, and both N and M are positive integers. Signal energy of the M subcarriers is not equally distributed. This helps frequency selective fading undergone by subcarriers with high energy in the M subcarriers is basically the same, and the impact of the frequency selective fading on the frequency offset correction can be mitigated.