4TH MASTS MEETING

Konstantinos Kyriakopoulos

Loughborough University

2

Research Done

Implementation of the KS statistic algorithm for CoMo v0.2

Wavelet decomposition and reconstruction written in C

Compression of Network Performance Measurements using Wavelets and DCT

MRTG monitoring of test network

3

Compression of Network Performance Measurements

DCT and WT with 75% (L2) and 93% (L4) reduction

Bursty and non bursty signals

200220240260280300320

125497397121145169193217241265289313337361385409433457481505529553577601625649Time (hours)

Delay (ms)150170190210230250270290310330350

124477093116139162185208231254277300323346369392415438461484507530553576599622645Time (hours)

Delay (ms)

4

Constant 75% and 93% compression for Bursty signal

Signal Bursty

Transform DCT DCT WT WT

Reduction 75% 93% 75% 93%

Input (bytes) 2592 2592 2592 2592

Output (bytes) 648 164 648 164

Compression ratio 1:4 1:15.8 1:4 1:15.8

Mean abs error 5.39 8.05 4.35 7.44

Mean % error 2.99 4.25 2.23 3.86

5

Constant 75% and 93% compression for Non-Bursty signal

Signal Non-Bursty with abrupt change

Transform DCT DCT WT WT

Reduction 75% 93% 75% 93%

Input (bytes) 2688 2688 2688 2688

Output (bytes) 672 168 672 168

Compression ratio 1:4 1:16 1:4 1:16

Mean abs error 0.80 2.13 0.44 1.55

Mean % error 0.35 0.91 0.19 0.65

6

Variable compression triggered by KS statistic

KS statistic identifies general differences between 2 distributions

Level of compression depends on the KS critical value:

If KS value > Da then apply low compression else high

€

Da = c(a)n1+ n2

n1* n2

7

Variable compression for Bursty signal

Signal Bursty

Transform Wavelet

Reduction Variable reduction L2 and L4

Input file (bytes) 2592

Output file (bytes) 322

Compression ratio 1:7.8 (similar to constant L3)

Mean abs error 6.46

Average % error 3.34

8

Variable compression for Non-bursty signal

Signal Non-bursty

Transform Wavelet

Reduction Variable reduction L2 and L4

Input file (bytes) 2688

Output file (bytes) 236

Compression ratio 1:11.4

Mean abs error 0.55

Average % error 0.24

9

Conclusions

Wavelets adapt to sudden changes better than DCT

For bursty signal, V.C. gives same results as a L3 WT

For the non bursty signal V.C. gives a compression ratio close to that of a L4 WT while keeping the error close to an error of a L2 WT

10

Future Work

Wavelet module for CoMo Integration of KS and Wavelet modules Quantization of wavelet coefficients and

application of Huffman coding SNMP query Cierna core switches??