Randomized Spreading Codes for Covert Satellite Communication
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Solution Overview
Problem
Existing spread spectrum communication methods fail to completely conceal the presence of wireless communication, allowing adversaries to detect and locate transmitters due to the use of predictable spreading codes.
Innovation Solution
Implementing a system with dynamic, randomly variable spreading codes synchronized between user equipment and ground stations to ensure continuous synchronization and conceal the communication by using different codes for each symbol transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional spread spectrum communication with fixed spreading codes is used, then communication can be established with low power density, but adversaries can detect and locate transmitters by processing received signals with known spreading codes
Solution Approach 1:
The patent applies dynamics by transitioning from fixed spreading codes to dynamically changing spreading codes. The spreading code changes periodically or randomly during communication, preventing adversaries from using static code processing to detect and locate transmitters. This dynamic code variation maintains communication reliability while eliminating the vulnerability to detection.
Solution Approach 2:
The patent changes the parameter of spreading code identity over time. By periodically or randomly switching between different spreading codes from a predefined set, the system alters the code parameter dynamically. This parameter change ensures that adversaries cannot successfully process received signals with known fixed codes, thereby preventing detection while maintaining reliable communication.
2Object-affected harmful factors
If spreading codes are changed frequently to prevent detection, then concealment improves, but synchronization between transmitter and receiver becomes more complex
Solution Approach 1:
The patent applies preliminary action by pre-synchronizing the spreading code sequences between transmitter and receiver before communication begins. Both parties agree on the code changing pattern, sequence, and timing in advance. This preliminary synchronization simplifies the implementation of dynamic code changes during communication, as both ends already know which code to use at each time interval without requiring complex real-time negotiation.
Solution Approach 2:
The patent implements periodic action by changing spreading codes at regular time intervals. Both transmitter and receiver switch codes simultaneously according to a predetermined periodic schedule. This periodic code changing approach maintains concealment from adversaries while simplifying synchronization, as both parties follow the same time-based pattern without requiring complex coordination mechanisms.
Data Source
AI summary
According to one or more of the embodiments herein, systems and techniques are provided for concealed spread symbol communication. In particular, a system in accordance with the techniques herein relates to concealing communication (a reduced risk of being detected), particularly messages over satellites communication channels. The techniques herein provide additional message concealment by using a randomly variable sequence of spreading chips. The techniques also ensure that the randomized chip sequences used by the user equipment and by the ground station are synchronized.