Dual Layer Frequency Offset Acquisition for Wireless Signals
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Solution Overview
Problem
Wireless communication systems face significant performance loss due to frequency offset, making it difficult to accurately extract data payload from received signals, especially in noisy environments.
Innovation Solution
A dual layer frequency offset estimation technique is employed, using both coarse and fine frequency offset acquisition methods to determine and compensate for frequency offsets, improving estimation range and accuracy by processing received information based on a combination of first and second frequency offsets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single frequency offset estimation method is used, then the device complexity is low, but the measurement precision and estimation range are insufficient
Solution Approach 1:
The frequency offset acquisition is divided into two distinct stages: coarse frequency offset acquisition and fine frequency offset acquisition. Each stage uses different estimation methods appropriate to its purpose, with the coarse stage handling large offsets and the fine stage providing precise correction. This segmentation allows the system to achieve high measurement precision without requiring a single overly complex estimation algorithm to handle all cases.
Solution Approach 2:
The patent extends the frequency offset acquisition process from a single-dimensional estimation to a two-dimensional approach by introducing both time-domain and frequency-domain processing. The fine frequency offset acquisition utilizes frequency domain analysis (FFT-based methods) in addition to time-domain correlation, adding another dimension of processing that enhances estimation accuracy while maintaining manageable device complexity through specialized processing for each dimension.
2Ease of manufacture
If differential receivers are used for low cost and good performance, then the ease of manufacture is improved, but the reliability deteriorates in the presence of frequency offset
Solution Approach 1:
The patent implements preliminary frequency offset compensation before the differential detection process. By acquiring and compensating for frequency offsets (both coarse and fine) prior to data extraction, the system prepares the received signal in advance to eliminate the harmful effects of frequency offset. This preliminary action ensures that the simple differential receiver structure can operate reliably without being degraded by frequency offset, maintaining both ease of manufacture and reliability.
Data Source
AI summary
Systems and techniques relating to wireless communications are described. A described technique includes determining a first frequency offset based on a received preamble of a wireless communication signal and a known preamble, the received preamble having been generated based on a spreading sequence and the known preamble, determining a second frequency offset based on the received preamble and the known preamble, and processing at least a portion of the wireless communication signal based on the first frequency offset and the second frequency offset. Determining the first frequency offset can include performing a multi-chip-level differential frequency offset acquisition that uses two or more chips associated with the received preamble. Determining the second frequency offset can include performing a symbol-level differential frequency offset acquisition that uses two or more symbols associated with the received preamble, where each of the two or more symbols are encoded by two or more chips.