Frequency Reference Signal Energy Shaping for Fading-Robust Offset Correction
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Solution Overview
Problem
Existing frequency offset correction methods fail to adequately address the impact of frequency selective fading, leading to poor frequency synchronization between the receive and transmit ends.
Innovation Solution
A communication method that involves generating a frequency reference signal with non-uniform energy distribution across frequency domain units, allowing for concentration of energy on specific units to mitigate the effects of frequency selective fading during frequency offset correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a frequency reference signal is used for frequency offset correction, then frequency synchronization between the receive end and transmit end is improved, but the impact of frequency selective fading cannot be mitigated, leading to residual frequency offsets
Solution Approach 1:
The patent applies local quality by creating non-uniform energy distribution across different frequency domain units in the frequency reference signal. Specifically, certain frequency domain units are allocated higher energy while others receive lower energy, allowing the signal to be more robust against frequency selective fading in specific frequency regions. This localized energy allocation ensures that even if some frequency components experience severe fading, the high-energy units maintain sufficient signal quality for accurate frequency offset correction.
Solution Approach 2:
The patent changes the energy distribution parameter of the frequency reference signal from uniform to non-uniform across frequency domain units. By adjusting the energy allocation parameter to concentrate energy in specific frequency domain units rather than distributing it evenly, the system adapts to mitigate frequency selective fading effects. This parameter change transforms the frequency reference signal's characteristics to improve reliability under fading conditions while maintaining frequency synchronization accuracy.
2Ease of manufacture
If energy of the frequency reference signal is uniformly distributed across all frequency domain units, then the signal structure is simple, but frequency selective fading causes differential fading on different subcarriers, degrading frequency offset correction performance
Solution Approach 1:
The patent applies asymmetry by intentionally creating an asymmetric energy distribution pattern across frequency domain units. Instead of symmetric uniform distribution, the system allocates energy asymmetrically where specific frequency domain units receive higher energy concentrations. This asymmetric structure directly counters the differential fading effects caused by frequency selective fading, as the high-energy units are positioned to compensate for the most affected frequency regions, thereby improving frequency offset correction accuracy despite the increased structural complexity.
3Reliability
If energy is concentrated on specific frequency domain units, then the impact of frequency selective fading is mitigated, but the energy distribution becomes non-uniform requiring more complex signal processing
Solution Approach 1:
The patent applies segmentation by dividing the frequency reference signal into multiple frequency domain units and allocating energy non-uniformly across these segments. Each frequency domain unit is treated as a separate segment with its own energy allocation, allowing targeted mitigation of frequency selective fading in specific frequency regions. This segmentation approach enables the system to handle fading effects locally in each segment while maintaining overall signal integrity, balancing the increased processing complexity with improved reliability.
Data Source
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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 distribution of energy of the frequency reference signal be mainly concentrated on one or more of the M subcarriers, so that 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.