Doppler-Based Satellite Uplink for GPS-Free Low-Power IoT Nodes
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Solution Overview
Problem
Existing systems for data transmission between resource-constrained ground-based devices and non-geostationary satellites, such as LEO satellites, require GPS for positioning, leading to high cost and energy consumption, and suffer from issues like signal collisions, variable interference levels, and non-constant coverage, which degrade Quality of Service (QoS).
Innovation Solution
A method involving Doppler shift estimation using beacon signals from non-geostationary satellites to determine transmission windows and frequencies, eliminating the need for GPS and reducing energy consumption by implementing an awaken mode for signal reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GPS positioning system is used to predict satellite passage and optimize transmission, then transmission reliability is improved, but device cost and energy consumption increase significantly
Solution Approach 1:
The patent extracts the positioning function from the GPS system by using satellite-beam-based relative positioning. Instead of requiring GPS receivers on ground devices, the system uses the satellite's own positioning and beam orientation to determine relative positions, thereby eliminating the need for expensive and power-consuming GPS hardware while maintaining transmission reliability.
Solution Approach 2:
The patent introduces an intermediary positioning mechanism where the satellite acts as a mediator for position determination. The satellite broadcasts its position and beam orientation information, which ground devices use to calculate relative positions without needing their own independent positioning systems. This intermediary approach eliminates the need for GPS on ground devices.
2Measurement precision
If ephemeris data is transmitted regularly to ensure accurate satellite passage prediction, then transmission precision is improved, but satellite bandwidth consumption and ground device power consumption increase
Solution Approach 1:
The patent segments the positioning information into discrete broadcast elements transmitted at specific intervals. Instead of continuous ephemeris data streams, the satellite broadcasts position and beam orientation data at defined time slots, allowing ground devices to update their predictions only when needed. This segmentation reduces bandwidth consumption while maintaining prediction precision.
Solution Approach 2:
The patent implements periodic broadcasting of positioning data by the satellite at predetermined intervals. Ground devices wake up periodically to receive updated position information rather than requiring continuous data streams. This periodic action reduces both satellite bandwidth consumption and ground device power consumption while ensuring sufficient prediction accuracy for transmission optimization.
3Reliability
If ground devices wake up continuously to receive satellite signals, then connection reliability is improved, but energy consumption increases
Solution Approach 1:
The patent implements periodic wake-up cycles where ground devices transition between low-power sleep mode and active reception mode. Devices wake up at predetermined intervals to receive satellite position and beam orientation data, then return to sleep mode. This periodic action maintains connection reliability through regular data updates while dramatically reducing energy consumption compared to continuous operation.
Solution Approach 2:
The patent performs preliminary calculations of satellite passage times and beam orientation at lower precision levels during sleep mode, then refines these predictions when awake. This allows devices to maintain adequate connection reliability without needing to be fully awake and processing continuously, as preliminary actions are performed in advance during low-power states.
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
Ground-based devices can transmit data to non-geostationary satellites with low energy consumption and cost, while avoiding collisions and maintaining QoS, even in mobile and occulted environments.
Implementation Method 1
Performing successive Doppler shift estimations, a Doppler shift estimation of the Doppler shift estimations comprising: Receiving, by the ground-based device during the awaken mode, at least one signal from the non-geostationary satellite, the signal comprising at least one frequency parameter of the current reception frequency used by the non-geostationary satellite
Data Source
AI summary
A method for the transmission to a non-geostationary satellite of data stored by a ground-based device being carried out by the device, includes entering an awaken mode, performing successive Doppler shift estimations: receiving, by the device during the awaken mode, a signal from the satellite including a frequency parameter and an elevation emission criterion, performing a Doppler shift estimation based on the frequency of the received signal; estimating a Doppler rate of frequency change to obtain a relative position of the device, defining a transmission window during which the position of the device relative to position of the satellite verifies the elevation emission criterion, and if the position of the device relative to the position of the satellite verifies the elevation emission criterion: emitting at the frequency parameter a signal including the data stored by the device.