Orthogonal Spread Spectrum Indoor Location Estimation
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Solution Overview
Problem
Current indoor navigation methods, such as Time-of-Flight (ToF) measurement, face significant scheduling, medium, and storage overheads, necessitating more efficient approaches to estimate distances between stations in indoor environments where GNSS signals are unavailable.
Innovation Solution
A method involving a requesting station transmitting a configuration message to responding stations to generate and transmit orthogonal spread spectrum signals, allowing the requesting station to determine time of flight (TOF) and calculate its location based on these signals, utilizing a transmitter, receiver, and controller configured for spread spectrum operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Time-of-Flight measurement method is used for indoor navigation, then distance estimation capability is improved, but scheduling overhead and medium overhead increase significantly
Solution Approach 1:
The patent implements periodic action by using spread spectrum signals that are transmitted in structured time intervals with specific patterns. The requesting station sends a first spread spectrum signal, and responding stations reply with second spread spectrum signals in a periodic exchange pattern, reducing the need for complex scheduling while maintaining measurement precision.
Solution Approach 2:
The patent applies parameter changes by transforming the measurement approach from traditional ToF with extensive scheduling to spread spectrum-based measurement where the signal parameters (orthogonal codes, frequency spreading) are changed to enable implicit time measurement without complex scheduling overhead.
2Measurement precision
If Time-of-Flight measurement method is used for indoor navigation, then distance estimation capability is improved, but storage overhead increases significantly
Solution Approach 1:
The patent extracts only the essential measurement information from complex ToF measurements. By using spread spectrum correlation techniques, the system extracts distance information directly from signal correlation peaks without storing extensive scheduling data, reducing storage overhead while maintaining measurement precision.
3Loss of information
If orthogonal spread spectrum signals are used for response, then multiple responding stations can be distinguished, but signal processing complexity increases
Solution Approach 1:
The patent uses copying by having each responding station transmit a spread spectrum signal that is a coded version (copy with orthogonal code) of the reference signal pattern. The requesting station correlates received signals with known orthogonal codes to distinguish different stations, maintaining signal differentiation while using efficient correlation-based processing rather than complex analysis.
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
This approach reduces overheads by enabling efficient distance estimation and location calculation, improving indoor navigation accuracy and reducing resource utilization.
Implementation Method 1
a correlator configured to perform a cross-correlation operation on the first spread spectrum signal and the correlation signal to determine a peak
Implementation Method 2
wirelessly transmitting, by the requesting station, the first spread spectrum signal; wirelessly receiving, by the requesting station, a plurality of second spread spectrum signals
Data Source
AI summary
A method of determining a location of a requesting station includes: transmitting a configuration message to a plurality of responding stations to configure the responding stations to transmit, in response to a first spread spectrum signal, a plurality of second spread spectrum signals; wirelessly transmitting the first spread-spectrum signal; wirelessly receiving the second spread spectrum signals; determining time of flight (TOF)s based on the second spread spectrum signals; and determining, the location using the determined TOFs, wherein the second spread spectrum signals are orthogonal to each other.