GNSS Signal Synchronization Using Conjugate Product Frequency Estimation
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Solution Overview
Problem
Global Navigation Satellite Systems (GNSS) face challenges in accurately synchronizing signals due to frequency uncertainty, leading to computational inefficiencies and resource constraints in receivers, especially when dealing with secondary codes in modern constellations like Beidou and Galileo.
Innovation Solution
The implementation of a computationally efficient method for code phase synchronization of spread spectrum signals, which involves a single-dimensional search in the secondary code chip transition domain using complex conjugate products and reference sequences to determine code and frequency offsets, reducing the need for extensive processing power and resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional multi-dimensional search methods are used for code phase synchronization, then measurement precision is improved, but device complexity and computational requirements increase significantly
Solution Approach 1:
The patent segments the synchronization problem into two independent parts: frequency offset estimation and code phase offset estimation. By first estimating frequency offset using conjugate products and then using this estimate to correct the signal before code phase search, the complex multi-dimensional search is divided into simpler sequential steps, reducing overall computational complexity while maintaining accuracy
Solution Approach 2:
The patent transforms the two-dimensional search space (frequency offset and code phase offset) into a sequence of one-dimensional searches. By introducing the frequency offset estimation dimension first and using it to correct the signal, the remaining code phase search becomes a simpler one-dimensional problem, effectively reducing the search complexity from O(N*M) to O(N) + O(M) where N and M are the search spaces for frequency and code phase respectively
2Measurement precision
If extensive processing power is allocated to signal synchronization, then measurement precision is improved, but use of energy increases
Solution Approach 1:
The patent divides the energy-intensive synchronization process into two stages: frequency offset estimation using conjugate products (lower computational load) and code phase search (higher computational load). This segmentation allows the system to perform the simpler frequency estimation first, reducing the overall energy burden while achieving the necessary synchronization accuracy
Solution Approach 2:
The patent performs preliminary frequency offset estimation before the code phase search. By estimating and correcting frequency offset in advance using the conjugate product method, the subsequent code phase search operates on a pre-corrected signal, reducing the computational iterations needed and thereby reducing energy consumption
3Device complexity
If frequency offset is not corrected before code phase search, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent segments the synchronization process into frequency correction and code phase search stages. By explicitly separating these functions and performing frequency offset correction first using conjugate products, the patent ensures that the code phase search operates on frequency-corrected data, maintaining high measurement precision while keeping the overall device complexity manageable through functional decomposition
Data Source
AI summary
Wireless communication synchronization at a wireless signal receiver is described. A wireless signal received may be a spread spectrum signal containing a periodic extension of a primary code, a periodic extension of a secondary code, and a data portion. The receiver may determine a first chip sequence representative of the secondary code by extraction of the primary code and the data portion from a first received wireless signal. The receiver may further determine, from a second received wireless signal, a second chip sequence representative of the secondary code by extraction of the primary code from the second received wireless signal. The receiver may identify a phase offset associated with the received wireless signals by analyzing the first chip sequence and the second chip sequence.