Receiver Spreading Code Switching Synchronization
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Solution Overview
Problem
Existing satellite communication systems face challenges in quickly switching from short-period spreading codes to long-period spreading codes, leading to synchronization delays and vulnerability to jamming and interference, as well as difficulties in identifying short-period spreading codes used by third parties.
Innovation Solution
A radio communication system that employs two correlators to detect the switching time from a short-period spreading code to a long-period spreading code, allowing for immediate synchronization and resistance to jamming by using the satellite station to adjust its spreading code based on received AES key information, eliminating the need for periodic FSD transmission and reducing the risk of synchronization disruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a long-period spreading code is used to prevent jamming and interference identification, then security against jamming is improved, but synchronization establishment time increases significantly
Solution Approach 1:
The patent applies preliminary action by having the ground station prepare and transmit the AES key information to the satellite station before the actual code switching occurs. This allows the satellite station to pre-process and synchronize its local pseudorandom code generator with the incoming long-period spreading code, significantly reducing the synchronization establishment time when the switch to long-period code occurs.
Solution Approach 2:
The patent introduces an intermediary mechanism - a synchronization signal containing AES key information - that mediates between the ground station's code switching action and the satellite station's code synchronization. This intermediary signal carries the necessary key material that enables the satellite station to rapidly align its local code generator with the received long-period spreading code without requiring lengthy synchronization procedures.
2Reliability
If periodic FSD transmission is used for synchronization, then code synchronization is achieved, but vulnerability to pulse jamming increases
Solution Approach 1:
The patent extracts the essential synchronization function from the periodic FSD transmission framework. Instead of relying on periodic synchronization signals, the system extracts and transmits only the necessary AES key information through an intermediary synchronization signal. This eliminates the periodic transmission structure that is vulnerable to pulse jamming while maintaining the ability to achieve code synchronization through the extracted key material.
Solution Approach 2:
The patent converts the potential harm of periodic transmission vulnerability into benefit by replacing the periodic FSD structure with an event-driven synchronization signal. The harmful periodicity is eliminated, and the system benefits from asynchronous, on-demand synchronization that cannot be effectively jammed by pulse interference, while still achieving reliable code alignment through the AES key-based intermediary signal.
3Loss of time
If short-period spreading code is used for initial communication, then synchronization establishment is fast, but vulnerability to identification and jamming increases
Solution Approach 1:
The patent applies dynamics by implementing a time-varying code structure where the system transitions from short-period spreading codes during initial communication to long-period spreading codes for secure operation. The spreading code period is dynamically adjusted based on the communication phase and security requirements, allowing the system to benefit from fast synchronization during setup while achieving high security during normal operation.
Solution Approach 2:
The patent changes the parameter of spreading code period from short to long as the communication progresses. Initially, short-period codes are used for rapid synchronization establishment. After the AES key exchange and intermediary signal transmission, the system switches to long-period spreading codes, fundamentally changing the code period parameter to enhance security against identification and jamming while maintaining the benefits of initial fast synchronization.
Data Source
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AI summary
A receiver (300) includes a reception antenna (301), a reception unit (351), and a demodulation unit (352). The reception unit (351) sequentially receives modulated signals resulting from spread spectrum via the reception antenna (301). The demodulation unit (352) demodulate a first signal received by the reception unit (351) by performing despreading using a short-period spreading code, the first signal including information for identifying a long-period spreading code. The demodulation unit (352) identifies the long-period spreading code on the basis of the information obtained from the first signal. The demodulation unit (352) then demodulates a second signal received by the reception unit (351) after the first signal by performing despreading using the long-period spreading code.