SLCE-Based PRN Sequences for Navigation Signal Acquisition
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Solution Overview
Problem
Satellite navigation systems face challenges in deep indoor environments due to low signal power levels, and existing spreading codes often have limitations in length, leading to ambiguity and interference issues, which affect positioning accuracy and acquisition time.
Innovation Solution
The use of Sidelnikov/Lempel/Cohn/Eastman (SLCE) generative sequences to create a family of pseudo-random noise (PRN) sequences with even length, balanced properties, and optimized correlation performance, allowing for efficient signal acquisition and reduced cross-channel interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional PRN sequences are used for satellite navigation, then the system can operate in open sky environments, but the signals cannot be effectively received in deep indoor environments due to low power levels
Solution Approach 1:
The patent changes the fundamental parameters of the spreading code by using SLCE sequences with even length and optimized correlation properties. This allows the receiver to achieve better signal detection performance through improved auto-correlation and cross-correlation characteristics, enabling reliable reception of low-power signals in deep indoor environments without increasing transmitted power
2Measurement precision
If longer PRN sequences are used to reduce ambiguity and improve positioning accuracy, then positioning accuracy improves, but acquisition time increases
Solution Approach 1:
The patent employs SLCE sequences with specifically optimized parameters including even length and balanced properties. These parameter changes enable the sequence to achieve low ambiguity function values and excellent correlation properties, allowing accurate positioning to be achieved with shorter effective processing times compared to conventional sequences
Solution Approach 2:
The patent performs preliminary optimization of the spreading code selection and configuration before signal acquisition. By pre-selecting SLCE sequences with optimal correlation properties and configuring the receiver accordingly, the system prepares the best possible acquisition conditions in advance, significantly reducing the time required for signal acquisition while maintaining high positioning accuracy
3Productivity
If multiple transmitters use the same carrier frequency and modulation scheme, then spectrum efficiency is improved, but cross-channel interference increases making signal separation difficult
Solution Approach 1:
The patent assigns different local qualities to each transmitter by using distinct SLCE sequences with optimized cross-correlation properties. Each sequence is specifically designed to have low cross-correlation with other sequences in the system, enabling the receiver to locally differentiate between signals from different transmitters even when they share the same carrier frequency and modulation scheme, thus reducing cross-channel interference while maintaining spectrum efficiency
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The SLCE-based PRN sequences provide improved signal acquisition and reduced interference, enabling better positioning accuracy and flexibility in code selection for satellite navigation systems, including deep indoor environments.
Implementation Method 1
a correlator for correlating the PRN sequences supplied by the code module with an incoming signal
Data Source
AI summary
One embodiment of the invention provides a receiver for use in a navigation system comprising multiple transmitters. Each transmitter transmits a positioning signal comprising a pseudo-random noise (PRN) sequence corresponding to the respective transmitter. The receiver comprises a code module for supplying multiple PRN sequences corresponding to the respective multiple transmitters; and a correlator for correlating the PRN sequences supplied by the code module with an incoming signal. The multiple PRN sequences are based on a single Sidelnikov/Lempel/Cohn/Eastman (SLCE) generative sequence uSLCE, and each of said multiple PRN sequences, denoted ui satisfies the equation: ui=uSLCE⊕TiuSLCE, where ⊕ indicates element by element binary XOR addition, and Ti indicates a cyclic shift of i chips.