PRACH Frequency Offset Estimation for Large Time Delays
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Solution Overview
Problem
Existing frequency offset estimation methods in LTE/NR communication systems are limited to specific application scenarios, particularly failing to accurately estimate frequency offsets beyond the 1-fold subcarrier interval, which restricts their applicability in scenarios with large time delays and frequency offsets, such as low-orbit satellite systems.
Innovation Solution
A method and device for estimating frequency offsets in communication systems that involves acquiring main and secondary peaks of a PRACH signal, determining a first frequency offset, performing frequency offset compensation, and calculating a second frequency offset to accurately estimate time delays, thereby expanding the range of applicable scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the restriction set method is adopted to avoid frequency offset affecting time delay estimation, then time delay estimation accuracy is improved within 1-fold subcarrier frequency offset range, but the method becomes inapplicable when frequency offset exceeds 1-fold subcarrier interval
Solution Approach 1:
The frequency offset estimation is divided into two stages: first estimating the frequency offset within 1-fold subcarrier interval using the restriction set method, then using this result to compensate and estimate the remaining frequency offset. This segmentation allows each stage to operate within its optimal range while achieving overall wide-range accuracy.
Solution Approach 2:
The restriction set method is applied first to obtain a preliminary frequency offset estimate within 1-fold subcarrier interval. This preliminary result is then used as the basis for subsequent compensation and further estimation, enabling the system to handle larger frequency offsets beyond the initial restriction set range.
2Device complexity
If frequency offset compensation is performed using only the restriction set method, then estimation is simplified within limited range, but accurate estimation of large frequency offsets becomes impossible
Solution Approach 1:
The frequency offset compensation process is segmented into two parts: first using the restriction set method for initial compensation within 1-fold subcarrier interval, then performing additional compensation based on the estimated frequency offset. This segmentation maintains relative simplicity while achieving accurate estimation for large frequency offsets.
Solution Approach 2:
Initial frequency offset compensation is performed using the restriction set method to obtain a preliminary compensated signal. This preliminary compensation enables subsequent accurate estimation of the remaining frequency offset, achieving overall accuracy without requiring complete compensation in a single step.
Data Source
AI summary
A frequency offset estimation method, device, communication device and storage medium are provided. The method comprises: acquiring a main peak and a secondary peak of a PRACH signal when detecting that an access signal is in the PRACH signal sent by the signal sending end, wherein the PRACH signal is composed of a preset number of identical leader sequences; determining a first frequency offset according to a peak value of the main peak and a peak value of the secondary peak; performing a frequency offset compensation on the PRACH signal according to the first frequency offset, to obtain a compensation sequence after the frequency offset compensation; and calculating a frequency offset between the compensation sequence and the leader sequences, to obtain a second frequency offset, so as to estimate a time delay of the access signal according to the second frequency offset.