Effectiveness of Mobility Robustness Optimisation in a Live LTE Network
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Journal Title
Journal ISSN
Volume Title
Sähkötekniikan korkeakoulu |
Master's thesis
Authors
Date
2019-12-16
Department
Major/Subject
Communications Engineering
Mcode
ELEC3029
Degree programme
CCIS - Master’s Programme in Computer, Communication and Information Sciences (TS2013)
Language
en
Pages
55+6
Series
Abstract
This thesis focuses on the effectiveness of Mobility Robustness Optimisation (MRO), a Self Organising Network (SON) use case for LTE networks, in a live mobile network. Self Organising Networks reduce network complexity by employing automated algorithms, thereby reducing or even eliminating human intervention. An algorithm is developed to be deployed as part of the centralised SON solution of Finnish mobile network operator Elisa. The objective of the algorithm is to reduce radio link failures in the operator’s LTE network. Radio link failures cause temporary disruption in connectivity, which negatively affect user experience. The network was first analysed for different kinds of handover problems such as late, early, and pingpong handovers. The problems were found to be severe amongst intra-frequency handovers, compared to inter-frequency handovers. Further analysis revealed that in majority of cases, the handover problems are not dominant at cell level, but rather limited to certain cell-pairs. Therefore, a cell-pair level optimisation strategy focusing on intra-frequency handovers was devised for the network. Based on this strategy, an MRO algorithm that adjusts the cell-pair level parameter Cell Individual Offset (CIO) was developed. The algorithm was tested on a cluster of cells in the mobile operator’s live network. Results show that the algorithm is able to reduce the rate of radio link failures by up to 40 percent. Performance analysis also shows that there is a trade-off between early and late handover optimisation as well as late handover optimisation and pingpong handover optimisation.Description
Supervisor
Tirkkonen, OlavThesis advisor
Ahmed, FurqanJokela, Tommi
Keywords
LTE, SON, MRO, handover, optimisation