SBIR-STTR Award

The primary objective of Phase 1 of the proposed project is to design a ground-based protocol to provide reliable and efficient communication services by overcoming the problems associated with fading and blockage by terrain obstacles. The protocol will address both voice and data communication. In particular, the protocol must overcome the low and variable quality of service offered on mobile satellite links and provide reliable and timely indicators of link availability and quality to the users. Seamless communication service is desired as the users move through varied terrain. The protocol will use techniques such as data compression, forward error correction, acknowledgement and retransmission protocol, instantaneous rerouting, caching, and proxies to achieve this goal.

Benefits:
Considerable improvement in data communication rates and reliability is also possible through the development of a link layer protocol designed and adapted for satellite link qualities. Through a combination of variable forward error correction coding and an active acknowledgement and retransmission protocol the link quality can be improved to that expected by transport protocols such as TCP. Somewhat less improvement is possible for voice communications, as that medium does not lend itself to certain repair techniques (such as retransmission) that are very effective with data.

Keywords:
satellite communications, SATCOM, networking, protocols, blockage mitigation

During Phase 1, we designed and simulated the Spatially Redundant (SPRED) link layer protocol to overcome the problems caused by blockage in satellite on the move communication systems. Our objective during Phase 2 is to test, validate, and demonstrate the operation of the protocol on prototype hardware. The link layer protocol provides reliable and efficient communication services by overcoming the problems associated with blockage by terrain obstacles. The protocol addresses both voice and data communication. The protocol combines standard communications protocol techniques, such as forward error correction, selective acknowledgements, and repeat request retransmission with a novel fast switching algorithm to provide nearly seamless connectivity to a small cadre of cooperating satellite terminals. A military convoy equipped with several satellite communication vehicles would form such a cadre. By rapidly switching which terminal in the cadre is in active use, the protocol avoids the blockages and provides high capacity and reliability to the entire convoy. Validation of the algorithms, protocols, and actual software is necessary in advance of incorporation into satellite terminal designs and fabrication in Phase 3, both to avoid costly mistakes and to attract financing for such an endeavor. We test the system for correct operation, delivery latency, capacity, and reliability.

Keywords:
Satellite Communications, Satcom, Networking, Protocols, Blockage Mitigation