| dc.description.abstract | Quality of Service (QoS) in real-time media applications can be defined as the
ability to guarantee the delivery of packets from source to destination over best-effort
networks within some constraints. These constraints defined as the QoS metrics are
end-to-end packet delay, delay jitter, throughtput, and packet losses. Transporting
real-time media applications over best-effort networks, e.g. the Internet, is an area
of current research. Both the Transmission Control Protocol (TCP) and the User
Datagram Protocol (UDP) have failed to provide the desired QoS. This research aims
at developing application-level end-to-end QoS controls to improve the user-perceived
quality of real-time media applications over best-effort networks, such as, the public
Internet.
In this research an end-to-end packet based approach is developed. The end-to-
end packet based approach consists of source buffer, network simulator ns-2, destina-
tion buffer, and controller. Unconstrained model predictive control (MPC) methods
are implemented by the controller at the application layer. The end-to-end packet
based approach uses end-to-end network measurements and predictions as feedback
signals. Effectiveness of the developed control methods are examined using Matlab
and ns-2. The results demonstrate that sender-based control schemes utilizing UDP
at transport layer are effective in providing QoS for real-time media applications
transported over best-effort networks. Significant improvements in providing QoS are
visible by the reduction of packet losses and the elimination of disruptions during the
playback of real-time media. This is accompanied by either a decrease or increase in
the playback start-time. | en |
