Rate Adaptive Modem Dynamic Waveform Selection
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Solution Overview
Problem
Conventional satellite and terrestrial wireless modems have fixed parameters for symbol rate, modulation, and coding, which limits user data rate and bandwidth efficiency, requiring systems to be taken offline to change settings, leading to suboptimal performance under varying atmospheric conditions.
Innovation Solution
A rate adaptive modem system that dynamically selects waveforms based on carrier-to-noise ratio, allowing for real-time adjustment of modulation and coding to maximize user data rate while maintaining reliable communication, using a transmission frame format with a sync field, header, payload, and embedded channel for data and control information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional modems use fixed parameters for symbol rate, modulation, and coding, then system reliability is maintained under worst-case conditions, but bandwidth efficiency and user data rate are reduced
Solution Approach 1:
The modem dynamically adjusts modulation and coding parameters based on real-time channel conditions. The system transitions from fixed parameters to adaptive parameters that change with atmospheric conditions, allowing the user data rate to vary between minimum and maximum values while maintaining communication reliability through continuous monitoring and adjustment of the transmission waveform.
2Reliability
If modems are configured for worst-case transmission conditions, then communication reliability is ensured, but bandwidth efficiency is compromised during favorable conditions
Solution Approach 1:
The system changes physical parameters (modulation type, coding rate, symbol rate) based on atmospheric conditions. During favorable conditions, the modem uses higher-order modulation and faster coding rates to maximize bandwidth efficiency. During storm conditions, it automatically transitions to more robust, lower-rate configurations, eliminating the need to always operate at worst-case settings.
3Adaptability or versatility
If the system is taken offline to change modulation and coding parameters, then parameter adjustment is possible, but communication downtime occurs
Solution Approach 1:
The modem maintains continuous communication while adapting parameters in real-time. The system monitors atmospheric conditions and adjusts modulation and coding rates without interrupting the data stream, ensuring uninterrupted useful action. This eliminates the need to take the system offline for reconfiguration, as parameters are dynamically adjusted during operation.
4Device complexity
If a single transmission waveform is used for all conditions, then device complexity is reduced, but adaptability to varying atmospheric conditions is limited
Solution Approach 1:
The modem is designed with multi-functionality to handle diverse atmospheric conditions using a single device. It incorporates multiple transmission waveforms and automatically selects the appropriate modulation and coding scheme based on channel conditions. This universal design allows the same modem to operate efficiently in both clear-sky and storm conditions without requiring multiple specialized devices.
Data Source
AI summary
A communication system transmitting signals over a network using a transmission waveform in which a plurality of data packets are transmitted in a payload field of a transmission frame, the system includes a transmitter, which has a transmitting portion that sends information including user data in the data packets and a user data rate portion that dynamically changes the data rate of the user data to the highest rate possible for current link conditions by changing the waveform. The communication system also includes a receiver, which has a receiving portion that receives the information data packets and a reconfiguration portion that reconfigures the receiving portion based on the waveform parameters.