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Mobility Management in 5G Heterogeneous Networks: A Handover Scheme for Reducing Handover Failures
Mobile/cellular communications have become very popular and advanced significantly in recent decades. Communications will inevitably evolve into the next generation of wireless communications, in which users will be connected via heterogeneous networks. Small cell (SC)-based ultra-dense heterogeneo...
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| Format: | Thesis |
| Language: | Eng |
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Department of Electrical Engineering
2024
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| Summary: | Mobile/cellular communications have become very popular and advanced significantly in recent decades. Communications will inevitably evolve into the next generation of wireless communications, in which users will be connected via heterogeneous networks. Small cell (SC)-based ultra-dense heterogeneous networks (HetNets), which are underlaid on the coverage of a macro cell, are among the most promising alternatives for increasing capacity and coverage in 5G cellular networks. An ultra-dense network (UDN) refers to a setup in which the density of Radio Access Technologies (RATs) in a geographical area is increased. As a result, the areas covered by individual RATs begin to overlap. UDNs are regarded as a critical technology for 5G due to their capability to enhance connection quality and expand system capacity. There, small base stations (SBS) are located close to each other in a UDN. As a result, signals from two or more SBS can be received by a single user equipment (UE). This could lead to severe inter-cell interference. This usually happens when a handover has been delayed. If that happens, then, the handover command message (HCM) will not be received by the UE from its serving BS and, a handover failure (HOF) will be declared. Inter-cell interference is so severe in dense small cells that it occurs frequently, thus degrading signal quality and hence resulting in poor services to users. This dissertation focuses on reducing handover failures due to the unavailability of resources at the target cell when a user equipment moves out of small cells, which have the highest rate of handover failure. By utilising a semi-Markov mobility prediction algorithm for handover management, we have implemented a handover scheme that reduces the number of handover calls dropping. This paves the way for resources in the target base station to be reserved beforehand and thus reducing the number of handover failures significantly. The results of the proposed scheme were validated with a simulation in MATLAB with an environment consisting of small cells with different radio access technologies. From the simulation results, the prediction of the next location of the user equipment yielded lower handover call dropping as compared to new calls blocking as they were not predicted and hence resources not reserved for them. |
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