Doppler-Corrected Modem-Satellite Transmission
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Solution Overview
Problem
Data transmission between devices and relay stations faces challenges such as high power consumption and difficulties in handling Doppler shifts caused by relative motion between satellites and devices on Earth, leading to congestion and interference issues.
Innovation Solution
A system where devices on Earth, equipped with trajectory data and a data processor, calculate and compensate for Doppler shifts in transmitted signals, and a relay station with a signal-processing device corrects Doppler shifts in received signals, using Enhanced Spread Spectrum Aloha (E-SSA) protocol to efficiently process and transmit data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If devices transmit data simultaneously when satellite passes, then data transmission speed increases, but congestion and interference problems occur
Solution Approach 1:
The system implements periodic time-slotted transmission where devices in different geographic regions are assigned specific time windows for data transmission. As the satellite moves through different orbital positions, different regions gain transmission opportunities in a periodic cycle, ensuring fair access while preventing simultaneous collisions that cause congestion and interference.
2Area of stationary object
If satellite moves at high speed to improve coverage, then area coverage increases, but Doppler shift problems worsen
Solution Approach 1:
The system performs preliminary Doppler compensation by calculating expected frequency shifts based on satellite ephemeris data and device locations before transmission begins. Devices pre-adjust their transmission frequencies to account for anticipated Doppler effects, and the satellite applies additional compensation during signal processing, maintaining frequency accuracy despite high-speed motion that enables broad coverage.
3Productivity
If more devices connect simultaneously, then network capacity increases, but power consumption and processing load increase
Solution Approach 1:
The system segments the network into multiple geographic regions, each with its own time slot for transmission. This segmentation allows many devices to connect to the satellite over time without requiring simultaneous transmission, reducing peak power consumption and processing load while maintaining high overall network capacity through the coordinated time-division multiplexing of regional transmissions.
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 power consumption and improves data transmission accuracy by compensating for Doppler shifts, thereby minimizing congestion and interference, allowing for efficient data transfer between devices and relay stations, even at high relative speeds.
Implementation Method 1
calculates a Doppler shift based upon said trajectory data, and said device is configured to modify said signal for compensating a Doppler shift of said signal that results from said travelling with respect to one another
Implementation Method 2
said relay station receives signals from a population of devices arranged at the celestial body, said signals comprising said data in data packages
Data Source
AI summary
A device in a population of devices arranged at a celestial body for transmitting data to a relay station orbiting the celestial body. The relay station and the population of devices are to travel with respect to one another such that the relay station is to receive signals that include the data in data packages from the population of devices. The device includes trajectory data of the relay station, a transmitter to use the trajectory data so as to transmit a signal that is part of the signals, a data processor, and a computer program which, when executing on the data processor, is to calculate a Doppler shift based upon the trajectory data, and modify the signal to thereby compensate for the Doppler shift of the signal that results from the travelling of the relay station and the population of devices with respect to one another.