Network Coding Meets TCP

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 slidingwindow 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.

Providing Reliable Services over Wireless Networks Using a Low Overhead Random Linear Coding Scheme

“…Other interesting solution, proposed by Sundarajan et al [27], keeps TCP as the transport protocol, and improves its performance over wireless networks by integrating a coding module above the network layer. Besides, they proposed a proprietary acknowledgment mechanism, which is used by the destination to confirm the reception of meaningful information.…”

“…Another line would be the integration of on-the-fly decoding, as proposed by Sorensen et al [25]; these would allow decoding some packets before the coding matrix is complete, thus reducing the latency. In addition, we would also like to incorporate some congestion control mechanisms is the proposed protocol, following an approach similar to the one presented in [27].…”

An Implementation of Network Coding with Association Policies in Heterogeneous Networks

“…Process Model The network coding protocol as described in [1], [2] is implemented in a new OPNET process model. The sender NWC module generates and sends R random linear combinations of the packets in the coding window.…”

“…It has proven its merits over traditional routing and forwarding approaches by considering data as algebraic entities that can be modified inside the elements of both wireline and wireless networks [6], [7], [8]. We use the solution proposed in [1], [2] and implement it in the widely used OPNET Modeler [9]. Following [1] the model introduces a network coding layer between the transport and network layers of the TCP/IP protocol stack.…”

“…We use the solution proposed in [1], [2] and implement it in the widely used OPNET Modeler [9]. Following [1] the model introduces a network coding layer between the transport and network layers of the TCP/IP protocol stack. This solution does not require any changes to the behavior of the Transmission Control Protocol (TCP) or the Internet Protocol (IP) as packets are seamlessly transmitted across the known interfaces [2].…”