Slide title In CAPITALS 50 pt Slide subtitle 32 pt ANALYSING EFFECTS OF MALFUNCTIONS ON THE PERFORMANCE OF UMTS RADIO ACCESS NETWORKS Author: Antti Keintola.

Slide titleIn CAPITALS

50 pt

Slide subtitle 32 pt

ANALYSING EFFECTS OF MALFUNCTIONS ON THE

PERFORMANCE OF UMTS RADIO ACCESS NETWORKS

Author: Antti Keintola

Supervisor: Professor Sven-Gustav HäggmanInstructor: M.Sc. Anna Merjamaa

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© Ericsson AB 2005 Antti Keintola 2006-01-312

Agenda

Background Research problem and objectives Methods Analysis Results Summary


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Background

3G networks are launched all over the world Technology is complex and still somewhat immature Not much experience in operating and troubleshooting

the network Networks are not performing at the optimal level Faults and failures occur Troubleshooting is time consuming and finding the root

cause is difficult Performance statistics is sometimes the only source of

information available


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Research problem and objectives

What faults contribute most on the performance degradation?

Is it possible to find the cause of the failure by inspecting statistics?

What actions should be performed to improve performance?


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Methods

Counter data was collected from a live network– 7 RNCs, 1906 Node Bs– 28 day period– Only daily statistics, not hour or quarter data available

Improvements made simultaneously Data analysed with spreadsheet tool

– Laborious, slow– Need for dedicated tool


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Key Performance Indicators defined:– Call Completion Success Rate (CCSR)– Accessibility– Retainability

CCSR = Accessibility * Retainability

Methods


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Analysis – network

The net degradation of performance were calculated and dominant days were identified

Detailed analysis focused on days highlighted with red and yellow

Day Net contrib.

Day Net contrib.

1 3,50% 15 3,85%

2 3,69% 16 3,92%

3 2,91% 17 4,08%

4 2,63% 18 3,20%

5 3,29% 19 2,76%

6 3,61% 20 3,40%

7 4,14% 21 3,99%

8 4,52% 22 3,75%

9 3,67% 23 3,91%

10 3,43% 24 3,25%

11 2,80% 25 3,41%

12 4,81% 26 3,46%

13 3,36% 27 3,33%

14 3,87% 28 3,44%


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Analysis – accessibility

Accessibility was studied first– Almost all accessibility failures related to RRC rejects


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Analysis – RRC at RNC level

Six distinct faults were identified by analysing RNC RRC statistics


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Analysis – retainability

Speech and packet drops were studied separately


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Analysis – Radio Access Bearers

Drop rate analysis were done at RNC level– Basically RAB releases were investigated


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Results – accessibility failures

Following defects were identified and their net contribution to the overall performance were calculated

Transmission fault affects three out of seven RNCs, hence higher figure

Software and hardware defects have small impact on the overall performance

Fault Net contribution

Parameter fault 2,19%

Software fault 1,09%

AAL2 fault 1,62%

Hardware failure

0,95%

Cabling fault in core network

1,20%

Transmission fault

4,22%


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Results – accessibility failures


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Results – retainability failures

Speech calls

Packet connections


Software fault 1,66%

Hardware failure

1,25%

Transmission fault

6,68%


Design fault 10,72%

Parameter fault 11,29%


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Results – retainability failures


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Summary

Defects with significant impact on the network performance were identified

Impacts on the performance were calculated

Man-made defects have more severe impacts than software or hardware faults

The reasons for man-made faults should be worked out Working instructions and procedures should be revised and

improved Need for dedicated tool to analyse data from customer network


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Traffic properties


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Traffic properties


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Traffic properties


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Traffic properties


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Slide title In CAPITALS 50 pt Slide subtitle 32 pt ANALYSING EFFECTS OF MALFUNCTIONS ON THE PERFORMANCE OF UMTS RADIO ACCESS NETWORKS Author: Antti Keintola.

Documents

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