TECHNOLOGY AREAS: Information Systems

ACQUISITION PROGRAM: Automated Digital Network Systems

OBJECTIVE: Optimized coding, e.g., Forward Error Correction (FEC), and protocols will be developed for robust and reliable free-space optical communications that link to Transport Control Protocol /Internet Protocol (TCP/IP) maritime and expeditionary networks.

DESCRIPTION: Future service oriented networks will require high bandwidth for efficient C2 and ISR reachback from the tactical theater. Due to their high bit rate capability (Gbps and beyond) in addition to reduced SWaP (size, weight and power) and spectrum alleviation, free-space optical links will be attractive over RF for these maritime and expeditionary environments (ship-to-ship, ship-to-shore, ship-to-air, and air-to-shore).

However, optical communications in these environments experience data loss from: (1) atmospheric attenuation (fog, heavy rain, snow, dust) resulting in total loss for minutes to hours and, (2) atmospheric turbulence (scintillation) with short milliseconds burst errors. It is the atmospheric turbulence errors that are targeted in this work. The most common techniques to mitigate atmospheric turbulence are to (i) increase power, i.e., provide extra link margin to fill the fade depth, (ii) provide aperture averaging or use adaptive optics, (iii) provide diversity (multi-wavelength) as well as (iv) channel coding (block coding/interleaving) and protocols. It is the channel coding and protocols that are targeted in this work.

The atmospheric optical fading channels are not well characterized, nor are the efficacy of FEC for such models well understood. Therefore, related coding and error correction technologies, techniques, and mechanisms are very much hard problems for research. The characterization and mitigation of atmospheric properties causing slow fading are still academic topics as indicated in reference 2 of this SBIR proposal.

Specifically, this SBIR intends to investigate and characterize, interaction and impact of these coding schemes and interleaving on memory requirements, latency, retransmission strategies for both TCP/IP unicast and multicast services will need to be well understood to develop the optimized codes and protocols for high bit rate free-space optical communications. The appropriate combination of physical layer FEC, link layer packet/frame coding and/or retransmission strategies, and end-to-end network reliability mechanisms will be identified and a solution developed.

PHASE I: Utilize/Characterize maritime and expeditionary free-space optical communications channel statistics and provide tradeoff studies on channel codes/protocols, receiver hardware/firmware and Quality-of-Service impact. Provide a technical approach and supporting selection rational to migrate and mature an optimized FEC/protocol system for Phase II.

PHASE II: Develop optimized FEC/protocol system for connection to TCP/IP networks. Test integrated FEC and adaptive error correction and TCP/IP using actual full duplex maritime and expeditionary laser communications links.

PHASE III: This technology would be employed to support reliable high bandwidth links in both maritime and expeditionary environments to provide video, C2, and ISR information. Potential Acquisition Programs for transition include Automated Digital Network Systems (ADNS), Consolidated Afloat Network Enterprise Services (CANES), and Control on-the-move Digital Over the Horizon Relay (CoNDOR).

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Variants of this technology could be employed in maritime ship to ship and ship to air communications and by emergency services during disasters recovery operations and when SATCOM is unavailable.

REFERENCES:
1. "Evaluation of FEC for the Atmospheric Optical IM/DD Channel," by H. Henniger, F. David and D. Giggenbach, Free-Space Laser Communication Technologies XV, Proceedings of the SPIE, 2003.

2. "Evaluation of the scintillation loss for optical communication systems with direct detection," by N. Perlot, in Optical Engineering, Feb. 2007.

3. "A digital fountain approach to asynchronous reliable multicast", by Byers, Luby and Mitzenmacher, IEEE Sel areas in Comms Oct. 2002

KEYWORDS: Atmospheric Turbulence; FEC; Laser Communications; Network Reliability Mechanisms Protocol; TCP/IP

TPOC: Santanu Das
Phone: (703)588-1036
Fax: (703)696-1331
Email: [email protected]
2nd TPOC: Christopher Rigano
Phone:
Fax:
Email: [email protected]
3rd TPOC: Holly Lane
Phone:
Fax:
Email: [email protected]

** TOPIC AUTHOR (TPOC) **

DoD Notice:   Between November 13 and December 9, 2007, you may talk directly with the Topic Author(s) to ask technical questions about the topics. Their contact information is listed above. For reasons of competitive fairness, direct communication between proposers and topic authors is not allowed starting December 10, 2007, when DoD begins accepting proposals for this solicitation.

However, proposers may still submit written questions about solicitation topics through the DoD's SBIR/STTR Interactive Topic Information System (SITIS), in which the questioner and respondent remain anonymous and all questions and answers are posted electronically for general viewing until the solicitation closes. All proposers are advised to monitor SITIS (08.1 Q&A) during the solicitation period for questions and answers, and other significant information, relevant to the SBIR 08.1 topic under which they are proposing.

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