33 research outputs found
A system for online compression of high-speed network measurements
Measuring various metrics of high speed and high capacity networks pro-
duces a vast amount of information over a long period of time, making the conventional
storage of the data practically ine cient. Such metrics are derived from packet level
information and can be represented as time series signals. Thus, they can be ana-
lyzed using signal analysis techniques. This paper looks at the Wavelet transform as a
method of analyzing and compressing measurement signals (such as delay, utilization,
data rate etc.) produced from high-speed networks. A live system can calculate these
measurements and then perform wavelet techniques to keep the signi cant information
and discard the small variations. An investigation into the choice of an appropriate
wavelet is presented along with results both from o -line and on-line experiments.
The quality of the decompressed signal is measured by the PSNR and a comparison of
compression performance is presented against the lossless tool bzip2
Using wavelets for compression and detecting events in anomalous network traffic
Monitoring and measuring various metrics of highdata
rate networks produces a vast amount of information over
a long period of time making the storage of the monitored data
a serious issue. Furthermore, for the collected monitoring data
to be useful to network analysts, these measurements need to be
processed in order to detect interesting characteristics.
In this paper wavelet analysis is used as a multi-resolution
analysis tool for compression of data rate measurements. Two
known thresholds are suggested for lossy compression and event
detection purposes. Results show high compression ratios while
preserving the quality (quantitative and visual aspects) and
the energy of the signal and detection of sudden changes are
achievable
Wavelet compression techniques for computer network measurements
Wavelet transform is a recent signal analysis tool that is
already been successfully used in image, video and
speech compression applications. This paper looks at the
Wavelet transform as a method of compressing computer
network measurements produced from high-speed
networks. Such networks produce a large amount of
information over a long period of time, requiring
compression for archiving. An important aspect of the
compression is to maintain the quality in important
features of signals. In this paper two known wavelet
coefficient threshold selection techniques are examined
and utilized separately along with an efficient method for
storing wavelet coefficients. Experimental results are
obtained to compare the behaviour of the two threshold
selection schemes on delay and data rate signals, by using
the mean square error (MSE) statistic, PSNR and the file
size of the compressed output
Compressing computer network measurements using embedded zerotree wavelets
Monitoring and measuring various metrics of high data
rate and high capacity networks produces a vast amount of
information over a long period of time. Characteristics such
as throughput and delay are derived from packet level information
and can be represented as time series signals. This
paper looks at the Embedded Zero Tree algorithm, proposed
by Shapiro, in order to compress computer network delay
and throughput measurements while preserving the quality
of interesting features and controlling the level of quality
of the compressed signal. The quality characteristics that
are examined are the preservation of the mean square error
(MSE), the standard deviation, the general visual quality
(the PSNR) and the scaling behavior. Experimental results
are obtained to evaluate the behaviour of the algorithm on
delay and data rate signals. Finally, a comparison of compression
performance is presented against the lossless tool
bzip2
A live system for wavelet compression of high speed computer network measurements
Monitoring high-speed networks for a long period of time produces a high volume of
data, making the storage of this information practically inefficient. To this end, there
is a need to derive an efficient method of data analysis and reduction in order to archive
and store the enormous amount of monitored traffic.
Satisfying this need is useful not only for administrators but also for researchers
who run their experiments on the monitored network. The researchers would like to
know how their experiments affect the network's behavior in terms of utilization,
delay, packet loss, data rate etc.
In this paper a method of compressing computer network measurements while preserving
the quality in interesting signal characteristics is presented. Eight different
mother wavelets are compared against each other in order to examine which one offers
the best results in terms of quality in the reconstructed signal. The proposed
wavelet compression algorithm is compared against the lossless compression tool
bzip2 in terms of compression ratio (C.R.). Finally, practical results are presented by
compressing sampled traffic recorded from a live network
Applying wavelets for the controlled compression of communication network measurements
Monitoring and measuring various metrics of high-speed networks produces a vast amount of information over a long period of
time making the storage of the metrics a serious issue. Previous work has suggested stream aware compression algorithms, among
others, i.e. methodologies that try to organise the network packets in a compact way in order to occupy less storage. However, these
methods do not reduce the redundancy in the stream information. Lossy compression becomes an attractive solution, as higher
compression ratios can be achieved. However, the important and significant elements of the original data need to be preserved.
This work proposes the use of a lossy wavelet compression mechanism that preserves crucial statistical and visual characteristics
of the examined computer network measurements and provides significant compression against the original file sizes.
To the best of our knowledge, the authors are the first to suggest and implement a wavelet analysis technique for compressing
computer network measurements. In this paper, wavelet analysis is used and compared against the Gzip and Bzip2 tools for
data rate and delay measurements. In addition this paper provides a comparison of eight different wavelets with respect to the
compression ratio, the preservation of the scaling behavior, of the long range dependence, of mean and standard deviation and of
the general reconstruction quality. The results show that the Haar wavelet provides higher peak signal-to-noise ratio (PSNR) values
and better overall results, than other wavelets with more vanishing moments. Our proposed methodology has been implemented
on an on-line based measurement platform and compressed data traffic generated from a live network
Effect of discrete cosine and wavelet transformation based compression on the long range dependence of communication network performance measurements
This paper examines the impact of compression
methods on the long-range dependence of communication
network traffic measurements. The two compression methods
that are examined are based on the Wavelet transformation
and the Discrete Cosine Transformation (DCT). In order to
measure the length of long-range dependence of a stochastic
process, we first have to estimate the Hurst parameter. The
Hurst parameter is estimated by using the rescaled range
statistic (R/S) method. The Hurst values of the examined
signal, before and after the applied compression, are estimated
and compared. If the Hurst value of the compressed signal is
close to the Hurst value of the uncompressed signal, then the
compression algorithm has little interference on the longrange
dependence. The results show that Wavelet
transformation performs better than the DCT
A framework for cross-layer measurements in wireless networks
This paper formulates a framework for wireless network
performance measurements with the scope of being as
generic as possible. The methodology utilises a cross-layer
approach in order to address the limitations of traditional
layered techniques. A lot of work in the research community
uses the channel power (Cp) to predict performance
metrics in higher layers. There are currently two methods
to measure Cp; either by using a spectrum analyser or
from WiFi card information (RSSI). The paper discusses the
correct configuration of a spectrum analyser (SA), to measure
Cp. This paper, also provides a comparison of both SA
and RSSI results produced inside an anechoic chamber for
three different applications. The behaviour of the RSSI values
showed significant discrepancy with both the SA results
and what was intuitively expected. The results pinpoint the
necessity of a cross-layer approach and the importance of
carefully selected and positioned equipment for the accuracy
of the measurements
A framework for cross-layer measurement of 3G and Wi-Fi combined networks
3G networks and Wi-Fi networks could complement
each other as each has different advantages of coverage and
access capacity. A combined 3G and Wi-Fi network is one part of a
heterogeneous IP network which has ubiquitous access capacity.
However, the characteristics of the lower layers in the wireless
network portion of such a heterogeneous IP network could
significantly affect the performance of higher layers, and further,
the overall performance of the whole network. A single-layer
approach to performance analysis could not provide enough
information to present the correlation between lower and higher
layers. A cross-layer measurement approach for combined 3G and
Wi-Fi network is presented which aims to correlate the
characteristics of the physical layer (e.g. channel power and
signal-to-interference ratio) to key parameters of higher layer (e.g.
packet-loss ratio, and round trip time)
Processing network delay measurements into network events
Network performance monitoring is an ongoing process as networks and their users are constantly changing. Networks are subject to various changes, some of which are controlled by the network providers (such as upgrades or re-routes) and some are not (equipment failure, usage). Network monitoring may include the detecting of such changes. These changes can be referred to as network event