Coding versus feedback: Hybrid ARQ protocols for the packet erasure channel

This paper introduces hybrid ARQ protocols for the packet erasure channel - protocols that enable tradeoffs between complexity of encoding/decoding redundant packets and the amount of feedback needed for re-transmission requests. These protocols use adaptations of Tornado codes for erasure-correction on the forward link, and rate-distortion codes on the reverse link for feeding back the status of received packets. The resulting complexity-feedback tradeoffs are shown to be substantially better (in regimes of practical interest) than a naive protocol that simply time-shares between coding-only and feedback-only approaches.