Abstract
As the Internet is changing the world dramatically, an initiative is being proposed within NASA and in the military to expand the Internet into space and for network-centric warfare using network protocols. An end-to-end effective data transport protocol is critical to the reliable transfer of information in space and for a battlefield environment. Consequently, a reliable and efficient acknowledgment mechanism is required to accommodate these unreliable communication conditions. In this article we conduct a comparative investigation of existing data transport acknowledgment mechanisms for possible adoption in the unreliable environment of space or a similarly stressed communication environment. We also introduce the selective negative acknowledgment (SNACK), which is designed as a reliable retransmission mechanism for space and stressed tactical communications, followed by a brief performance evaluation of the effectiveness of SNACK compared to the standard SACK mechanism.