Congestion Control with Load Based Inter RAT Handover (3G to 2G): Case of Addis Ababa
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Date
2020-02
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Addis Ababa University
Abstract
Telecom operators have to manage their resources efficiently to minimize the congestion in their
telecommunication network. In Ethiopia, heterogeneous wireless networking technologies such as
GSM, UMTS, CDMA and LTE are being used to provide wireless access for both voice and data
services. In big cities, the densely populated areas like town centres, shopping centres and train
stations may have coverage of multiple wireless networks. Traditional Radio Access Technology
(RAT) selection algorithms are mainly based on the ‘Always Best Connected’ paradigm whereby the
mobile nodes are always directed towards the available network which has the strongest signal.
Hence a large number of mobile users may be connected to the more common UMTS while the other
networks like GSM and CDMA would be underutilised, thereby creating an unbalanced load across
these different wireless networks. This high variation among the load across different co-located
networks may cause congestion on overloaded network leading to high call blocking and call
dropping probabilities. This can be alleviated by moving mobile users from heavily loaded networks
to least loaded networks.
This thesis presents a load levelling algorithms which is used for load balancing in heterogeneous
wireless networks. The technique comprises of load-aware RAT selection techniques and network
load balancing mechanism. Different attributes like load distribution in all wireless networks, packet
drops, throughput at mobile nodes and network utilization have been observed to evaluate the
effects of load balancing using different scenarios. The simulation results indicate that with load
balancing the performance efficiency improves as the overloaded situation is avoided by load
balancing. The load change value is 11% for the sites in the focus area. This shows that the voice call
has been pushed to the neighbour 2G cell and congestion in 3G network has been improved.
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Keywords
WCDMA, Load control, Tele traffic Engineering, Load Balancing, load based InterRAT handover