Speeding Multicast by Acknowledgment Reduction Technique (SMART)

TL;DR

This paper introduces SMART, a feedback protocol for wireless multicast that reduces acknowledgment overhead using predictive modeling and NACK-based feedback, achieving near-omniscient performance and outperforming existing methods.

Contribution

The paper proposes SMART, a novel acknowledgment reduction technique for wireless multicast using predictive feedback and NACKs, improving scalability and robustness.

Findings

SMART performs nearly as well as an omniscient transmitter.

It outperforms current state-of-the-art methods across various conditions.

The scheme is robust to model uncertainties and feedback losses.

Abstract

We present a novel feedback protocol for wireless broadcast networks that utilize linear network coding. We consider transmission of packets from one source to many receivers over a single-hop broadcast erasure channel. Our method utilizes a predictive model to request feedback only when the probability that all receivers have completed decoding is significant. In addition, our proposed NACK-based feedback mechanism enables all receivers to request, within a single time slot, the number of retransmissions needed for successful decoding. We present simulation results as well as analytical results that show the favorable scalability of our technique as the number of receivers, file size, and packet erasure probability increase. We also show the robustness of this scheme to uncertainty in the predictive model, including uncertainty in the number of receiving nodes and the packet erasure probability, as well as to losses of the feedback itself. Our scheme, SMART, is shown to perform nearly as well as an omniscient transmitter that requires no feedback. Furthermore, SMART, is shown to outperform current state of the art methods at any given erasure probability, file size, and numbers of receivers.