Network coding meets TCP

TL;DR

This paper introduces a TCP-compatible network coding scheme that improves throughput over lossy wireless links by masking packet losses and enabling smooth congestion control, with minimal protocol modifications.

Contribution

It presents a novel TCP-integrated network coding method using ACKs as degrees of freedom, enhancing performance over lossy networks with incremental deployment.

Findings

Achieves higher throughput than TCP on lossy wireless links.

Reacts smoothly to packet losses, improving congestion control.

Ensures fairness and soundness of the proposed algorithm.

Abstract

We propose a mechanism that incorporates network coding into TCP with only minor changes to the protocol stack, thereby allowing incremental deployment. In our scheme, the source transmits random linear combinations of packets currently in the congestion window. At the heart of our scheme is a new interpretation of ACKs - the sink acknowledges every degree of freedom (i.e., a linear combination that reveals one unit of new information) even if it does not reveal an original packet immediately. Such ACKs enable a TCP-like sliding-window approach to network coding. Our scheme has the nice property that packet losses are essentially masked from the congestion control algorithm. Our algorithm therefore reacts to packet drops in a smooth manner, resulting in a novel and effective approach for congestion control over networks involving lossy links such as wireless links. Our experiments show that our algorithm achieves higher throughput compared to TCP in the presence of lossy wireless links. We also establish the soundness and fairness properties of our algorithm.