Configurable OFDM Modem for Satellite Uplink
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Solution Overview
Problem
The complexity of satellite wireless communication systems is increased due to the need for separate modems for each node, which complicates signal formats, bandwidth requirements, and communication protocols, and is further challenged by Doppler effects and signal-to-noise ratio issues caused by high satellite velocities and large distances between nodes.
Innovation Solution
A configurable modem that can process a single waveform for transmission and reception across satellite, satellite access gateway, and user terminal nodes, with adjustable parameters such as bandwidth, pilot symbols, and carrier frequency offset, enabling error correction and adaptable communication for both uplink and downlink channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate modems are developed for each node (satellite, gateway, user terminal), then each node can be optimized for its specific communication requirements, but the overall system complexity increases due to multiple different signal formats, bandwidth requirements, and communication protocols
Solution Approach 1:
The patent implements a universal modem architecture that can operate in multiple modes (satellite mode, gateway mode, user terminal mode) by configuring a single device with different waveform parameters and communication protocols. This eliminates the need for separate dedicated modems for each node type while maintaining optimized performance for each specific communication scenario.
Solution Approach 2:
The modem incorporates dynamic reconfiguration capabilities that allow it to adapt its signal format, bandwidth, and protocol parameters based on the current operational context. This enables a single modem to dynamically switch between different communication modes (uplink, downlink, different node types) without requiring hardware changes, thereby reducing system complexity while maintaining reliability.
2Reliability
If specialized modems are deployed for each node to address Doppler effects and signal-to-noise ratio issues, then communication quality is improved, but the number of different signal formats and communication protocols increases
Solution Approach 1:
The universal modem is designed to handle multiple signal formats and protocols within a single device architecture. It can process satellite-to-ground, ground-to-satellite, and gateway communications using the same hardware platform, reducing the diversity of signal formats while maintaining adaptability to different communication requirements through software-based configuration.
Solution Approach 2:
The modem employs parameter-based reconfiguration to adapt to different communication scenarios. By changing operational parameters (frequency offsets, bandwidth settings, protocol configurations) rather than hardware architecture, the system maintains signal quality for specialized applications while reducing the number of different signal formats needed across the network.
3Device complexity
If a configurable modem using a single waveform is used across all nodes, then system complexity is reduced and spectral efficiency is improved, but the ability to optimize for specific node requirements may be compromised
Solution Approach 1:
The configurable modem uses dynamic parameter adjustment to optimize communication for specific node requirements while maintaining a unified waveform structure. The modem can adapt carrier frequency offsets, bandwidth allocations, and protocol parameters in real-time based on the operational mode, ensuring reliable communication without requiring separate dedicated hardware for each node type.
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 modem provides flexible and efficient communication by enabling the same physical chip to be used across different nodes, improving spectral efficiency and handling various errors, including sampling frequency and carrier frequency offsets, thereby simplifying system design and enhancing signal quality.
Implementation Method 1
perform a Fast Fourier Transform (FFT) on the received signal
Implementation Method 2
Doppler effects and a variety of signal-to-noise ratio (SNR) issues can impact signal quality. Such issues can also vary depending on which two nodes are in communication and depending on the respective signal characteristics.
Data Source
AI summary
A modem is configurable on a satellite, user terminal or gateway generates a radio frequency (RF) signal using an orthogonal frequency division multiplexing (OFDM) protocol including a radio frame including one or more bursts. A burst of the one or more bursts includes a first portion including burst detection data, a second portion including channel characteristic estimation data, a third portion including payload data, and fourth and fifth portions including pilot data. The first portion in a time domain is included in the burst prior to the second, third, fourth, and fifth portions. The first portion can include a pseudo-random noise sequence inserted in the time domain. The same physical modem can be configured to transmit signals on an uplink or downlink between a user terminal and a satellite or on the uplink or downlink between the satellite and the gateway.