Circuit Switched UMTS to GSM Handover Neighbor List and Parameter Optimization: The Case of Ethio Telecom Addis Ababa Network
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Date
2022-02
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Addis Ababa University
Abstract
The rapid growth of mobile service users is forcing telecom operators to invest in new
infrastructure. However, looking for techniques for optimum network utilization that can
optimize the interoperability features among different technologies has the potential to reduce
investment costs for the deployment of infrastructure. Optimizing the circuit switched inter radio
access technology between universal mobile telephone system (UMTS) and global system for
mobile (GSM)) handover success rate failure allows the operator to use the ubiquitous 2G
network to provide service in the coverage discontinuity of the 3G network, as well as load
sharing between the networks.
In this thesis, based on the circuit switched inter radio access technology (CS IRAT) 3G-to-2G
handover success rate report data of the Addis Ababa network, a problematic sample IRAT
network has been chosen, and the handover is optimized for the sample network and interpreted
for the whole Addis Ababa network. First, with the help of Pareto techniques, the root cause of
the handover (HO) failure rate is analyzed using two months report data, and it is found that
physical channel failure is the main cause of the IRAT handover failure. Second, a sample
network (study area) is selected based on the HO success rate and the number of handover
attempts (success rate of 70% and number of attempts > 10,000 per day). Then methods to solve
the root cause of the problems were suggested (adjusting the neighbor relations and tuning the
target 2G network handover threshold) based on the different literature reviewed and the effects
of the parameters on the IRAT handover. With Atoll (planning tool), the sample network (real
network) identified is designed using engineering parameters of the network obtained from Ehtio
Telecom. Finally, using the sample network as an input, the neighbor relation is redefined and
the handover coverage of the network is optimized. It is found that the handover coverage area (a
possible location where a handover could occur) shrinks with the increase in the target 2G
network handover thresholds, which will lead to first a decrease in the total number of handover
attempts and, second, from the total, an increase in the success of those attempted handovers,
since the 2G cell gets stronger. The above two conditions result in an improvement in handover
success rate since it is the ratio of successful handovers to the total number of handovers.
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Keywords
CS IRAT (3G-to-2G) handover success rate,, Optimization, Handover, study area, Neighbor relation, Target(2G) Threshold