Methods for transmission and reception of a serial signal and corresponding devices

Patent metadata

Field	Value
Publication number	US-9831979-B2
Application number	US-201514836041-A
Country	US
Kind code	B2
Filing date	Aug 26, 2015
Priority date	Sep 9, 2014
Publication date	Nov 28, 2017
Grant date	Nov 28, 2017

Abstract

A device for transmitting a signal over a serial link includes a transmission processor to carry out, before transmission over the serial link, a scrambling process on successive initial packets of the signal to form a scrambled packet for each initial packet. The transmission processor includes an encoding circuit to carry out an encoding process on each initial packet to deliver an encoded packet. The encoding process includes, for each current initial packet starting from the second, encoding of the current initial packet with the preceding scrambled packet. Calculation circuitry determines, for each initial packet, a bit disparity of the encoded packet and determination of a cumulative bit disparity. Comparison circuitry carries out a comparison process involving the bit disparity of the encoded packet and the cumulative disparity, with the scrambled packet being the encoded packet or the inverted encoded packet, depending on the result of the comparison process.

First claim

That which is claimed is:

1. A method for transmitting a signal over a serial link comprising:
performing, before transmission over the serial link, a scrambling process on two successive initial packets of the signal to form a scrambled packet for each initial packet, the scrambling process comprising, for each initial packet
an encoding process to obtain an encoded packet, the encoding process comprising, for each current initial packet starting from a second packet, encoding of a current initial packet with a preceding scrambled packet,
a determination of a bit disparity of the encoded packet and a determination of a cumulative bit disparity, and
a comparison process involving the bit disparity of the encoded packet and the cumulative disparity, with the scrambled packet being the encoded packet or an inverted encoded packet, depending on a result of the comparison process.

2. The method according to claim 1 , further comprising formation of an indication of the result of the comparison to be transmitted over the serial link.

3. The method according to claim 1 , wherein the comparison process comprises a comparison between the absolute value of a difference between the cumulative disparity and the bit disparity of the encoded packet against an absolute value of a sum of the cumulative disparity and the bit disparity of the encoded packet.

4. The method according to claim 3 , wherein the scrambled packet is the encoded packet if the absolute value of the difference between the cumulative disparity and the bit disparity of the encoded packet is greater than or equal to the absolute value of the sum of the cumulative disparity and the bit disparity of the encoded packet, and an inverse of the encoded packet if the absolute value of the difference between the cumulative disparity and the bit disparity of the encoded packet is less than the absolute value of the sum of the cumulative disparity and the bit disparity of the encoded packet.

5. The method according to claim 1 , wherein the encoding of the current initial packet starting from the second packet comprises application of an invertible logical operator to the current initial packet and to the preceding scrambled packet.

6. The method according to claim 1 , wherein the process of encoding the first initial packet comprises encoding of the first initial packet with a scrambling key.

7. The method according to claim 6 , wherein the encoding of the first initial packet comprises application of a symmetrical and invertible logical operator to a first initial packet and to the scrambling key.

8. The method according to claim 1 , further comprising, before transmission over the serial link and before or after the scrambling process, performing an electromagnetic interference mitigation process on successive primary packets of the signal, and delivering successive processed primary packets.

9. The method according to claim 8 , wherein the electromagnetic mitigation process comprises, for each primary packet, encoding of the primary packet with an encoding key, with the encoding key being different from one primary packet to another, and the encoding key having a constant bit disparity from one encoding key to another.

10. The method according to claim 9 , wherein the encoding of the primary packet with the encoding key comprises the application of an invertible additional logical operator to the primary packet and to the encoding key.

11. A method for transmitting a signal over a serial link comprising:
performing, before transmission over the serial link, an electromagnetic interference mitigation process on successive primary packets of the signal and delivering successive processed primary packets, the mitigation process comprising, for each primary packet, encoding of the primary packet with an encoding key, the encoding key being different from one primary packet to another, and the encoding key having a constant bit disparity from one encoding key to another.

12. The method according to claim 11 , wherein the encoding of the primary packet with the encoding key comprises application of an invertible additional logical operator to the primary packet and to the encoding key.

13. A method for receiving a signal sent over a serial link comprising:
performing a descrambling process on successive scrambled initial packets of the signal and forming a descrambled packet for each scrambled initial packet, the descrambling process comprises, for each scrambled initial packet
a decoding process to obtain a decoded packet, the decoding process comprising, for each current received scrambled initial packet starting from a second packet, decoding of the current scrambled initial packet with the preceding descrambled packet, and with the descrambled packet being the decoded packet or an inverted decoded packet, depending on an indication associated with the scrambled initial packet and contained in the received signal.

14. The method according to claim 13 , wherein the decoding of the current scrambled initial packet starting from the second packet comprises application of a logical operator, which is an inverse of that used to obtain the current scrambled initial packet, to the current scrambled initial packet and to the preceding descrambled packet.

15. The method according to claim 14 , wherein the process of decoding the first scrambled initial packet comprises decoding of the first scrambled packet with a descrambling key identical to a scrambling key used to obtain the first scrambled initial packet.

16. The method according to claim 14 , wherein the decoding of the first scrambled initial packet comprises application of an inverse logical operator to the first scrambled initial packet and to the descrambling key.

17. The method according claim 13 , further comprising, before or after the descrambling process, performing an electromagnetic interference mitigation process on successive encoded secondary packets of the received signal and delivering successive processed secondary packets.

18. The method according to claim 17 , wherein the mitigation process comprises, for each encoded secondary packet, decoding of the encoded secondary packet with an additional logical operator which is the inverse of that used to obtain the encoded secondary packet and a decoding key identical to an encoding key used to obtain the encoded secondary packet, with the decoding key being different from one encoded secondary packet to another, and the decoding key having a constant bit disparity from one decoding key to another.

19. The method according to claim 18 , wherein the decoding of the encoded secondary packet with the decoding key comprises the application of an additional EXCLUSIVE OR function to the secondary packet and to the decoding key.

20. A method for receiving a signal sent over a serial link comprising:
performing an electromagnetic interference mitigation process on successive encoded secondary packets of the received signal and delivering successive processed secondary packets, the mitigation process comprising, for each encoded secondary packet, decoding of the encoded secondary packet with an additional logical operator which is an inverse of that used to obtain the encoded secondary packet and a decoding key identical to an encoding key used to obtain the encoded secondary packet, the decoding key being different from one encoded secondary packet to another, and the decoding key having a constant bit disparity from one decoding key to another.

21. The method

Assignees

• Stmicroelectronics (Grenoble 2) Sas

Inventors

• Goulahsen Abdelaziz

Classifications

• G09C1/00

  Apparatus or methods whereby a given sequence of signs, e.g. an intelligible text, is transformed into an unintelligible sequence of signs by transposing the signs or groups of signs or by replacing them by others according to a predetermined system (cryptographic typewriters G09C3/00) · CPC title

• H04L9/0662

  with particular pseudorandom sequence generator · CPC title

• H04K1/00 Primary

  Secret communication · CPC title