A novel acknowledgment scheme for space Internet

The Transmission Control Protocol (TCP) employs an acknowledgment (ACK) mechanism for reliable transfer of information. Selective acknowledgment (SACK) and negative acknowledgment (NAK) are well-known acknowledgment schemes in the current Internet. Selective negative acknowledgment (SNACK) is a novel acknowledgment scheme which integrates the capabilities of both SACK and NAK and has been developed for space Internet. It is expected to have a detailed description of the SNACK scheme with the support of some experimental results. The paper provides a full description of the novel SNACK scheme, comparing it with the widely used SACK scheme. The description is supported by some experimental data obtained from file transfer tests using a space-to-ground link simulation (SGLS) test-bed. Sampled experimental results show that SNACK has no negative effects on throughput at a low BER, but makes better utilization of channel bandwidth and achieves significantly higher throughput in error prone links, such as satellite and wireless channels.