Tunable Expansion Packets for Fulcrum codes

Fulcrum combines two encoding stages, first using one high Galois field, such as GF(2(Exp 8)) and then with the binary Galois field GF(2). This allows intermediate and end devices, depending their computation power, to select either field to recode and decode coded packets. To ensure a high decoding probability, Fulcrum codes introduce r expansion packets at the outer coding stage, to increase the chance of producing linearly independent packets. However, the fixed number r hinder the chance of obtaining both high decoding probability and efficient transmission at a reduced computation complexity. We propose tunable expansion packet (TEP) protocols, which adjust the extra coefficients in the outer coding stage based on feedback from receivers. Comprehensive evaluations show that TEP protocols significantly increase goodput and reduce computation complexity while maintaining a low overhead.