SUBCHANNEL SECURITY AT THE OPTICAL LAYER

• US 20110206203A1
• Filed: 02/21/2011
• Published: 08/25/2011
• Est. Priority Date: 02/22/2010
• Status: Active Grant

• Current Assignee: Snell Holdings, LLC (Treq Labs, Inc.)
• Original Assignee: Vello Systems Incorporated
• Inventors: Voruganti, Pavan, May, Karl
• Granted Patent: US 8,705,741 B2
• Time in Patent Office: Days
• US Class Current: 380/256
• CPC Class Codes: H04K 1/04 by frequency scrambling, i.e. by transposing or inverting parts of the frequency band or by inverting the whole band
• CPC Class Codes: H04K 1/08 by varying the polarisation of transmitted waves
• CPC Class Codes: H04K 1/10 by using two signals transmitted simultaneously or successively

Abstract

The present invention includes various novel techniques, apparatus, and systems for optical WDM communications that involve dynamically modifying certain aspects of the WDM transmission (and corresponding receive) process at the optical (physical) layer to significantly enhance data/network security. These various dynamic modifications can be employed individually or in combination to provide even greater security depending upon the desired application and design tradeoffs. WDM transmission steps typically include encoding the client signals, mapping them to one or more subchannels within or across ITU channels, modulating them onto subcarrier frequencies, and multiplexing them together for optical transmission. By dynamically modifying one or more of these processing steps over time (in addition to any encryption of the underlying client signals), the current invention provides additional security at the physical (optical) layer of an optical network and thus greatly enhances overall network security.

Claims

1. A method of providing security at the physical layer of an optical network by processing client signals for transmission on a fiber optic cable of the optical network, the method comprising the following steps:

(a) encoding one or more client signals;

(b) buffering and synchronizing the encoded client signals;

(c) mapping the buffered and synchronized client signals to one or more subchannels within a single ITU channel or across multiple ITU channels;

(d) modulating the subchannels onto subcarrier frequencies;

(e) multiplexing together the signals on the subcarrier frequencies within each ITU channel, and the resulting combined signals on the ITU channel frequencies, to generate an optical signal for transmission along the fiber optic cable of the optical network; and

(f) modifying dynamically over time one or more of the processing steps (a)-(e).

3. The method of claim 1, wherein one or more of the dynamic modifications are triggered randomly over time.

4. The method of claim 1, wherein one or more of the dynamic modifications are triggered periodically over time.

5. The method of claim 1, wherein one or more of the dynamic modifications are triggered based upon the occurrence of a predetermined condition.

6. The method of claim 5, wherein the predetermined condition is the detection of an intrusion into the optical network.

7. The method of claim 1, wherein the encoding of the client signals is modified dynamically by alternating between scrambling standards G.709 and G.975.

8. The method of claim 1, wherein the buffering and synchronizing of the encoded client signals is modified dynamically by changing the data rates of the encoded client signals.

9. The method of claim 1, wherein the mapping of the buffered and synchronized client signals is modified dynamically by changing the mapping of one or more client signals from a previously mapped ITU channel or subchannel to a different ITU channel or subchannel.

10. The method of claim 1, wherein the modulation of the subchannels is modified dynamically to introduce a lambda drift of the subcarriers within an ITU channel window by shifting the subchannels together to occupy a slightly different portion of the ITU channel window.

11. The method of claim 1, wherein the modulation of the subchannels is modified dynamically by changing the polarization state of the subcarrier frequencies within an ITU channel.

12. The method of claim 1, wherein the modulation of the subchannels is modified dynamically by changing the modulation scheme employed to generate one or more subchannels.

2. A method of providing security at the physical layer of an optical network by processing an optical signal received on a fiber optic cable of the optical network, the method comprising the following steps:

(a) demultiplexing the optical signal into distinct ITU channel frequencies and subcarrier frequencies representing subchannels within each ITU channel;

(b) demodulating the demultiplexed signals into distinct subchannels;

(c) demapping the demodulated signals into one or more subchannels within a single ITU channel or across multiple ITU channels;

(d) buffering and synchronizing the demapped subchannels into distinct encoded client signals;

(e) decoding the encoded client signals to recover the original client signals transmitted by an originating node on the optical network; and

(f) modifying dynamically over time one or more of the processing steps (a)-(e) in accordance with an algorithm by which analogous steps were modified during transmission of the original client signals.