HF Frequency and Relay Selection Under Interference
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Solution Overview
Problem
High Frequency (HF) waveforms are susceptible to interference, leading to communication denial during active interference, which existing technologies like MIL-STD-188-110D waveforms are unable to effectively counteract, especially under extreme solar anomalies and intentional interferer nodes.
Innovation Solution
A software-defined radio system with a frequency selection algorithm and HF propagation model is used to select and place relay nodes, enabling communication links to operate beyond line-of-sight by selecting frequencies that overcome interference, utilizing a robust waveform protocol stack to maintain communication in the presence of interferers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If HF waveforms are used for long-range communication, then communication range is improved, but susceptibility to interference increases
Solution Approach 1:
The system dynamically changes frequency parameters to avoid interference. The frequency selection algorithm monitors interference conditions and switches to alternative frequencies within the HF band, allowing long-range communication to continue by adjusting the operating frequency parameter in response to changing interference conditions
Solution Approach 2:
Relay nodes serve as intermediaries to establish indirect communication paths when direct links are blocked by interference. The system selects optimal relay nodes from the network to forward communications, enabling long-range communication to persist by routing through intermediate nodes that are not subject to the same interference conditions
2Reliability
If relay nodes are added to overcome interference, then communication reliability is improved, but system complexity increases
Solution Approach 1:
The frequency selection algorithm automatically performs frequency selection and relay node selection without manual intervention. The system self-manages the complexity of coordinating multiple relay nodes by implementing autonomous algorithms that select optimal frequencies and relays based on current network conditions, maintaining high reliability while managing system complexity through automation
Solution Approach 2:
The system dynamically selects relay nodes and frequencies based on real-time interference conditions and network state. Rather than using fixed relay assignments, the system adapts its relay selection and frequency usage dynamically, allowing communication reliability to be maintained through flexible, condition-based routing while managing complexity through adaptive rather than static configurations
Data Source
AI summary
Techniques for selecting frequencies of operation are described. HF signals may land at the receiver node with power levels dependent upon the transmit frequency. The frequency with the highest power level at the receiver node may be selected when the receiver node is not subject to interference. The receiver node may be unable to receive a desired signal if an interfering signal has a signal level which is higher than the desired signal. The interfering signals may have a signal level which is higher across all available frequencies. The transmitter node may determine a potential relay table with a communication link between the transmitter node and a relay node and a communication link between the relay node and the receiver node. The communication link may include link margins above the interfering signal, ensuring the links may be established. The nodes may then communicate even when subject to interference.