On the Performances of User Association Enhancements in Dense Wireless Heterogeneous Networks
| dc.contributor.advisor | Hamalainen, Jyri (Prof.) | |
| dc.contributor.advisor | Yihenew, Wondie (PhD) | |
| dc.contributor.author | Dinkisa, Aga | |
| dc.contributor.author | Yihenew | |
| dc.date.accessioned | 2023-11-28T09:34:45Z | |
| dc.date.accessioned | 2023-11-28T14:09:05Z | |
| dc.date.available | 2023-11-28T09:34:45Z | |
| dc.date.available | 2023-11-28T14:09:05Z | |
| dc.date.issued | 2023-03 | |
| dc.description.abstract | User Association (UA) plays a signi cant role in radio resource management of wireless communication systems. Currently, network densi cation and heterogeneity have already been identi ed as a feasible solution for the exponentially expanding data service demand. Hence, UA methods must meet di erent requirements in dense and ultra dense Heterogeneous Networks (HetNets). The load-imbalance due to transmit power di erence between tiers and interference coordination challenges, the e ect of serving node intensity on load sharing and achievable throughputs and the e ort to satisfy certain users with high data rate demands are a few problems. Furthermore, the interconnected and complicated problems of service delivery are posed by the spatio-temporal dynamics in service demand and the mobility of User Equipment (UE). This thesis takes a step-by-step approach to solving UA problems in dense and ultra dense HetNets. This research uses stochastic geometry tools, system level simulations, and realistic test case deployment simulations. Models were created for each scenario based on the load balancing, interference coordination, varied densi cation levels, heterogeneity, and user mobility. The work's rst contribution is a solution to the problem of load imbalance and interference coordination. The proposed method is simple to integrate into an existing HetNets network, and the results demonstrate e ective load-aware association and adaptive interference coordination. A cell clustering-based load-aware o setting and an adaptive Low Power Subframe (LPS) approach was developed. The solution allows the separation of UA functions at the UE and network server such that users can make a simple cell-selection decision similar to that in the Maximum Received Signal Strength (max-RSS) based UA scheme, where the network server computes the load-aware o setting and required LPS periods based on the load conditions of the system. The proposed solution was evaluated using system level simulations wherein the results correspond to performance changes in di erent service regions. Results show that the method e ectively solves the o oading and interference coordination problems in dense HetNets. The second contribution of the research is on the coupled and decoupled User Association. It can be used as a guide for network operators to select the appropriate UA scheme for their network. The concepts of Poisson random networks were used to analytiv ically obtain the relative densi cation levels for which we need the o oading, decoupled or coupled UA and validate the analysis with numerical and system level simulation of realistic network. The association window, where users choose to use decoupled association in terms of the relative intensity, transmit powers at each tiers and the Path Loss Exponent (PLE) of the propagation environment, is derived. Further, the ergodic rate expressions in order to study throughput performances in di erent densi cation regions, which can be computed numerically, are formulated . To validate the theoretical analysis, numerical, system level simulation and realistic network analysis were used. The analytical, simulation, and realistic test case results provide insights for the operators about the densi cation ranges, where to use coupled or decoupled association. Finally, the research work focused on solutions for UEs with high data rate demands and mobility management. With Multiple Association (MA), user-centric clustering, control, and user-plane split usages were designed and investigated. Mobility management approaches in Long Term Evolution Advanced (LTE-A)/Fifth Generation (5G) and MA were used. The scheme attempts to separately treat UEs based on their speed by setting some prede ned thresholds. In addition, a clustering approach, which produce virtual cells with which UEs gets associated was developed. Combining of MA with clustering enhances cooperation between most appropriate cells to serve a given UE. The ndings indicate that the issues were addressed in an e cient and e ective manner. | en_US |
| dc.identifier.uri | http://etd.aau.edu.et/handle/12345678/32700 | |
| dc.language.iso | en_US | en_US |
| dc.publisher | Addis Ababa University | en_US |
| dc.subject | LTE/LTE-A | en_US |
| dc.subject | 5G | en_US |
| dc.subject | user association | en_US |
| dc.subject | load balancing | en_US |
| dc.subject | HetNets | en_US |
| dc.subject | cell densi- cation | en_US |
| dc.subject | service demand | en_US |
| dc.subject | cell range expansion | en_US |
| dc.subject | almost-blank subfram | en_US |
| dc.subject | inter-cell interference | en_US |
| dc.subject | clustering | en_US |
| dc.subject | downlink and uplink decoupling | en_US |
| dc.subject | multiple association | en_US |
| dc.subject | mobility management | en_US |
| dc.title | On the Performances of User Association Enhancements in Dense Wireless Heterogeneous Networks | en_US |
| dc.type | Thesis | en_US |