Concealed spread symbol communication

Patent metadata

Field	Value
Publication number	US-12355483-B2
Application number	US-202318095499-A
Country	US
Kind code	B2
Filing date	Jan 10, 2023
Priority date	Jan 10, 2022
Publication date	Jul 8, 2025
Grant date	Jul 8, 2025

Abstract

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.

First claim

What is claimed is:

1. A method, comprising:
coordinating, by a particular device, a random number seed that is generated by a beaconing device and transmitted to one or more remote devices;
generating, by the particular device, one or more random numbers based on the random number seed;
determining, by the particular device, one or more spreading code chips associated with the one or more random numbers; and
communicating, by the particular device, a spread spectrum message between the beaconing device and a specific remote device of the one or more remote devices based on one of either spreading or de-spreading the spread spectrum message according to the one or more spreading code chips.

2. The method as in claim 1 , wherein the beaconing device is a ground station for satellite communication, and wherein the one or more remote devices comprise mobile terminals.

3. The method as in claim 1 , wherein the random number seed is transmitted to the one or more remote devices via a broadcast message transmitted to all remote devices as part of a beacon signal from the beaconing device.

4. The method as in claim 1 , wherein the coordinating comprises:
generating the random number seed; and
transmitting the random number seed to the one or more remote devices within a beacon message.

5. The method as in claim 1 , wherein the coordinating comprises:
receiving the random number seed within a beacon message from the beaconing device.

6. The method as in claim 1 , wherein identifying the one or more spreading code chips associated with the one or more random numbers is based on one of either using a chip table or a computer program.

7. The method as in claim 1 , further comprising:
determining whether the random number seed is an update from a previously received random number seed, wherein generating the one or more random numbers and identifying the one or more spreading code chips is in response to the random number seed being the update from the previously received random number seed.

8. The method as in claim 1 , wherein the one or more random numbers and the one or more spreading code chips comprise a sequence of a plurality of random numbers and a sequence of a plurality of spreading code chips, respectively.

9. The method as in claim 1 , wherein the particular device is a transmitter, and wherein communicating comprises:
spreading symbols of the spread spectrum message according to the one or more spreading code chips; and
transmitting the spread spectrum message to a receiver device.

10. The method as in claim 9 , further comprising:
awaiting for a predetermined time to receive an acknowledgement from the receiver device that it has received the spread spectrum message;
in response to the acknowledgement not being received within the predetermined time, retransmitting the spread spectrum message; and
in response to the acknowledgement being received within the predetermined time, determining one or more next random numbers and one or more next spreading code chips associated with the one or more next random numbers for a next communication.

11. The method as in claim 1 , further comprising:
determining to initiate a communication to the specific remote device based on the beaconing device having the spread spectrum message to send to the specific remote device.

12. The method as in claim 11 , further comprising:
determining to initiate the communication to the specific remote device based additionally on receiving a request from the specific remote device for the beaconing device to transmit any messages intended to the specific remote device.

13. The method as in claim 1 , wherein the particular device is a receiver, and wherein communicating comprises:
de-spreading a received signal using the one or more spreading code chips into a de-spread signal; and
examining the de-spread signal to determine whether the received signal contains symbols associated with a message transmitted from a transmitter to the receiver.

14. The method as in claim 13 , further comprising:
determining, in response to no symbols being detected in the de-spread signal, update for the random number seed according to an update rule.

15. The method as in claim 13 , further comprising:
examining, in response to one or more symbols being detected in the de-spread signal, whether the one or more symbols signify an end of a communication;
in response to the one or more symbols signifying the end of the communication, returning an acknowledgment; and
in response to the one or more symbols not signifying the end of the communication; determining one or more new random numbers and one or more new spreading code chips associated with the one or more new random numbers to continue de-spreading the received signal.

16. The method as in claim 1 , wherein the one or more spreading code chips are based on an orthogonal variable spreading factor (OVSF) spread spectrum scheme.

17. The method as in claim 1 , wherein the particular device is a receiver, and wherein communicating comprises:
listening to received signals using a current spreading code chip associated with a current random number and a previous spreading code chip associated with a previous random number to account for communication delay between a transmitter and the receiver.

18. The method as in claim 1 , further comprising:
determining a potential breakdown in communication synchronization with the beaconing device; and
in response to the potential breakdown in communication synchronization, reverting back to listening for a beacon message for coordinating a current random number seed that is generated by the beaconing device and transmitted to the one or more remote devices.

19. A tangible, non-transitory, computer-readable medium storing program instructions that cause a computer of a particular device to execute a method comprising:
coordinating a random number seed that is generated by a beaconing device and transmitted to one or more remote devices;
generating one or more random numbers based on the random number seed;
determining one or more spreading code chips associated with the one or more random numbers; and
communicating a spread spectrum message between the beaconing device and a specific remote device of the one or more remote devices based on one of either spreading or de-spreading the spread spectrum message according to the one or more spreading code chips.

20. An apparatus, comprising:
a processor configured to execute one or more processes;
a communication interface; and
a memory configured to store a process executable by the processor that when executed is configured to:
coordinate a random number seed that is generated by a beaconing device and transmitted to one or more remote devices;
generate one or more random numbers based on the random number seed;
determine one or more spreading code chips associated with the one or more random numbers; and
communicate a spread spectrum message between the beaconing device and a specific remote device of the one or more remote devices based on one of either spreading or de-spreading the spread spectrum message according to the one or more spreading code chips.

Assignees

• Higher Ground Llc

Inventors

• Reis Darren Robert
• Reuss David Alexander
• Reis Robert S

Classifications

• H04B1/707 Primary

  using direct sequence modulation · CPC title