Avaliação experimental do protocolo DCCP para transmissão de conteúdos multimídia em redes sem fio 802.11g e na internet.

Abstract

In this dissertation it is presented the results for an experimental evaluation of the DCCP protocol (RFC 4340) when used to transmit multimedia data over 802.11g networks and over the Internet. During researches, it was analyzed the behavior of transmitted data flows using the DCCP protocol running on resource limited devices as well as on desktops. The approach adopted was to transmit DCCP data flows with other protocols flows, such as TCP and UDP. On these experiments, many different parameters related to the state of the connection were monitored such as throughput, the amount of data transmitted and lost, jitter. During some of the experiments’ session, the mobile devices were subjected to hand-offs operations, which has been used in mobile networks, using three wireless access points. As a result, this work shows that both TCP and DCCP share the bandwidth available in the network fairly. Nonetheless, it was also observed that the UDP data flows substantially degenerate both TCP and DCCP data flows while being transmitted through the use of TCP Reno and DCCP CCID-2 congestion-control algorithms. Besides the results and discussions around the experiments performed, other contributions of this work are highlighted as follows: the development of "Embedded Phone", a VOIP-based application using the DCCP protocol; the implementation of the DCCP CCID-4, a congestion-control algorithm as integral part of the Linux operating system; and the availability and maintenance of the DCCP protocol code for the Nokia maemo platform, which is also based on the Linux operating system.