Communication Engineering

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Browsing Communication Engineering by Author "Alemu, Yadessa"

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    Congestion Control with Load Based Inter RAT Handover (3G to 2G): Case of Addis Ababa
    (Addis Ababa University, 2020-02) Alemu, Yadessa; Yihenew, Wondie (PhD)
    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.