Ανάλυση Επίδοσης των Πρωτοκόλλων QUIC και TCP σε Δίκτυο LTE

Abstract

The deployment of wireless networks and the widespread use of smart mobile devices have led to a rapid increase in data traffic from Web Browsing and Video Streaming applications in the recent years. This trend is expected to magnify with the emergence of new technologies, such as the Internet of Things (IoT) and the 5th generation of wireless networks (5G). However, the protocol stack on which the Internet’s functionality is based and specifically the Transmission Control Protocol (TCP), despite the development of some improvements, has not changed in its core from when it was originally designed for wired networks. Today, TCP experiences certain well know issues, such as the lack of multiplexing capability in the transport layer, which causes the problem identified as Head of Line Blocking (HOL Blocking). Therefore, scientific interest was focused on the design of a new transport protocol. For this reason, the QUIC (Quick UDP Internet Connections) protocol was proposed by Google in 2013, which is implemented on top of the existing UDP (User Datagram Protocol). QUIC’s design builds on that of TCP for secure and reliable data transmission, but the two also present significant differences. This diploma thesis evaluates the performance of QUIC compared to TCP when operating over 4G networks (Long Term Evolution - LTE). The main goal is to examine different use cases and scenarios, in order to investigate the possible performance improvements of QUIC for modern wireless networks. The first chapter presents an overview of today’s Internet traffic in numbers and gives a brief introduction to the TCP/IP protocol stack. The second chapter presents the TCP protocol. The core functionalities that TCP offers are described, along with header formats and operational mechanisms. The third chapter is an extensive reference to QUIC protocol, with emphasis on the differences with TCP. The new transport streams, frame and packet formats, as well as flow and congestion control mechanisms are analyzed. The fourth chapter describes the LTE systems. Firstly, the Radio Access and Core Network architecture is presented and afterwards the design of the protocol stack and the operation of the physical layer. The fifth chapter focuses on the existing techniques for Mobile Acceleration, which is the optimization of TCP connections inside a wireless network and its possible applications on future QUIC connections. The sixth chapter studies the performance of QUIC and TCP over an LTE network, based on simulations of different use case scenarios.