Slow Hopping Anti-Jam Waveform for Unpredictable Frequency Hopping
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Solution Overview
Problem
Conventional wireless communications in A2AD scenarios are vulnerable to hostile jamming due to their narrow bandwidth and predictable frequency hopping patterns, which can be exploited by jammers, and increasing bandwidth is limited by regulatory constraints and hardware costs.
Innovation Solution
The Slow Hopping Anti-Jam (SHAW) protocol uses a cryptographic hash function to generate unpredictable hop sequences over multiple GHz bandwidths with long dwell times, enabling secure communication through direct-sequence spread spectrum modulation and cryptographic authentication for synchronization, making it difficult for jammers to predict or disrupt the communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional frequency-hopping spread spectrum (FHSS) is used to widen bandwidth for anti-jamming, then resistance to narrow-band jamming improves, but the system remains vulnerable to partial-band jamming and sweeping attacks because the hop sets are confined to a few hundred MHz and the hopping pattern is predictable
Solution Approach 1:
The patent divides the frequency spectrum into multiple non-contiguous hop sets separated by guard bands, rather than using a single contiguous bandwidth. This segmentation allows the system to jump across large frequency gaps (multiple GHz) while maintaining anti-jamming properties. The cryptographic hash function further segments the frequency space into discrete, unpredictable channels within each hop set.
Solution Approach 2:
The patent implements dynamic frequency hopping where the next frequency is determined by a cryptographic hash function of the current frequency and a secret key, creating an unpredictable, adaptive hopping pattern. This dynamic approach prevents jammers from predicting future frequencies or implementing effective partial-band jamming strategies.
2Reliability
If the bandwidth of conventional FHSS is increased to improve anti-jamming resilience, then resistance to jamming improves, but hardware cost and complexity increase due to requirements for faster ADCs
Solution Approach 1:
By segmenting the wide bandwidth into multiple non-contiguous hop sets, the patent allows the system to achieve wideband operation without requiring ultra-fast ADCs for the entire bandwidth simultaneously. The receiver only needs to process one narrow band at a time, switching between bands according to the cryptographic hopping sequence.
Solution Approach 2:
The patent uses software-based cryptographic hash functions to generate frequency sequences instead of requiring expensive, high-speed hardware ADCs. This software-driven approach provides wideband capability at lower hardware cost and complexity.
3Length of moving object
If satellite communications are used for long-distance communication in A2AD scenarios, then communication range improves, but the system becomes vulnerable to jamming and space-based attacks
Solution Approach 1:
The patent replaces satellite-based communication infrastructure with a ground-based cryptographic frequency-hopping system. Instead of relying on vulnerable satellite links, the system uses software-defined radio with cryptographic hash functions to establish secure, jam-resistant communication channels over long distances through directional waveforms.
4Adaptability or versatility
If HF and VHF point-to-point links are used for long-distance communication, then communication capability in denied satellite environments improves, but reliability deteriorates due to difficulty of establishing reliable links over long distances
Solution Approach 1:
The patent implements dynamic frequency selection using cryptographic hash functions that adapt to current communication conditions and securely select frequencies from multiple non-contiguous hop sets. This dynamic approach improves link reliability by avoiding jammed frequencies and exploiting available spectrum opportunities in real-time.
Solution Approach 2:
The system changes multiple parameters simultaneously - frequency, bandwidth, and hopping rate - based on cryptographic determinate sequences. This multi-parameter adaptation allows the system to maintain reliable communication over long distances in denied environments by continuously optimizing transmission characteristics.
Data Source
AI summary
A method of transmitting a message using a slow hopping anti-jam waveform, includes generating a sequence with a cryptographic hash function; transmitting, for a predetermined dwell time, a first portion of the message on a first channel having a first baseline frequency; choosing a second channel having a second baseline frequency based on the generated sequence, the second baseline frequency being offset from the first baseline frequency; and transmitting, for the predetermined dwell time, a second portion of the message on the second channel having the second baseline frequency; wherein the two transmitting steps occur sequentially.