Modeling Network Coded TCP Throughput: A Simple Model and its Validation

TL;DR

This paper develops and validates a simple analytical model to compare TCP and TCP with network coding in lossy wireless networks, demonstrating TCP/NC's robustness and throughput advantages.

Contribution

It introduces a straightforward model for TCP/NC throughput analysis and validates it with simulations, highlighting the benefits of network coding in lossy environments.

Findings

TCP/NC masks erasures, preventing performance degradation.

TCP/NC achieves higher throughput than TCP in lossy networks.

Simulations closely match analytical predictions, confirming robustness.

Abstract

We analyze the performance of TCP and TCP with network coding (TCP/NC) in lossy wireless networks. We build upon the simple framework introduced by Padhye et al. and characterize the throughput behavior of classical TCP as well as TCP/NC as a function of erasure rate, round-trip time, maximum window size, and duration of the connection. Our analytical results show that network coding masks erasures and losses from TCP, thus preventing TCP's performance degradation in lossy networks, such as wireless networks. It is further seen that TCP/NC has significant throughput gains over TCP. In addition, we simulate TCP and TCP/NC to verify our analysis of the average throughput and the window evolution. Our analysis and simulation results show very close concordance and support that TCP/NC is robust against erasures. TCP/NC is not only able to increase its window size faster but also to maintain a large window size despite losses within the network, whereas TCP experiences window closing essentially because losses are mistakenly attributed to congestion.