3 research outputs found
Multi-step-ahead prediction of MPEG-coded video source traffic using empirical modeling techniques
In the near future, multimedia will form the majority of Internet traffic and
the most popular standard used to transport and view video is MPEG. The MPEG
media content data is in the form of a time-series representing frame/VOP sizes.
This time-series is extremely noisy and analysis shows that it has very long-range
time dependency making it even harder to predict than any typical time-series. This
work is an effort to develop multi-step-ahead predictors for the moving averages of
frame/VOP sizes in MPEG-coded video streams.
In this work, both linear and non-linear system identification tools are used to
solve the prediction problem, and their performance is compared. Linear modeling is
done using Auto-Regressive Exogenous (ARX) models and for non linear modeling,
Artificial Neural Networks (ANN) are employed. The different ANN architectures
used in this work are Feed-forward Multi-Layer Perceptron (FMLP) and Recurrent
Multi-Layer Perceptron (RMLP).
Recent researches by Adas (October 1998), Yoo (March 2002) and Bhattacharya
et al. (August 2003) have shown that the multi-step-ahead prediction of individual
frames is very inaccurate. Therefore, for this work, we predict the moving average
of the frame/VOP sizes instead of individual frame/VOPs. Several multi-step-ahead
predictors are developed using the aforementioned linear and non-linear tools for
two/four/six/ten-step-ahead predictions of the moving average of the frame/VOP
size time-series of MPEG coded video source traffic.
The capability to predict future frame/VOP sizes and hence the bit rates will
enable more effective bandwidth allocation mechanism, assisting in the development
of advanced source control schemes needed to control multimedia traffic over wide
area networks, such as the Internet
Flow control of real-time unicast multimedia applications in best-effort networks
One of the fastest growing segments of Internet applications are real-time mul-
timedia applications, like Voice over Internet Protocol (VoIP). Real-time multimedia
applications use the User Datagram Protocol (UDP) as the transport protocol because
of the inherent conservative nature of the congestion avoidance schemes of Transmis-
sion Control Protocol (TCP). The e®ects of uncontrolled °ows on the Internet have
not yet been felt because UDP tra±c frequently constitutes only » 20% of the total
Internet tra±c. It is pertinent that real-time multimedia applications become better
citizens of the Internet, while at the same time deliver acceptable Quality of Service
(QoS).
Traditionally, packet losses and the increase in the end-to-end delay experienced
by some of the packets characterizes congestion in the network. These two signals
have been used to develop most known °ow control schemes. The current research
considers the °ow accumulation in the network as the signal for use in °ow control.
The most signi¯cant contribution of the current research is to propose novel end-
to-end °ow control schemes for unicast real-time multimedia °ows transmitting over
best-e®ort networks. These control schemes are based on predictive control of the
accumulation signal. The end-to-end control schemes available in the literature are
based on reactive control that do not take into account the feedback delay existing
between the sender and the receiver nor the forward delay in the °ow dynamics. The performance of the proposed control schemes has been evaluated using the
ns-2 simulation environment. The research concludes that active control of hard real-
time °ows delivers the same or somewhat better QoS as High Bit Rate (HBR, no
control), but with a lower average bit rate. Consequently, it helps reduce bandwidth
use of controlled real-time °ows by anywhere between 31:43% to 43:96%. Proposed
reactive control schemes deliver good QoS. However, they do not scale up as well as
the predictive control schemes. Proposed predictive control schemes are e®ective in
delivering good quality QoS while using up less bandwidth than even the reactive con-
trol schemes. They scale up well as more real-time multimedia °ows start employing
them