University of Technology Sydney. Faculty of Engineering and Information Technology.The demand for high speed network has led to the development of LTE. The LTE replaced circuit switched legacy systems into packet switched network. The high speed simultaneous transmission of data is achieved by using Orthogonal Frequency Division Multiple Access (OFDMA) in the downlink. To achieve high speed multimedia services in the downlink various packet scheduling algorithms have been proposed in the past. The LTE architecture has been simplified compared to 2G or 3G systems to a greater extent. The network elements namely Base Station Controller (BSC) and Radio Network Controller (RNC) have been replaced with eNodeB. The Radio Resource Management (RRM) functionality has been confined to eNodeB. To enable end users to achieve high data rates Heterogeneous Networks (HetNets) are used. In HetNets, the pico cells and femto cells work alongside the macro cells to deliver the required QoS. The objective of this thesis is to study the performance of LTE network through simulation and by observing the KPIs from real-time network.
The thesis starts with the performance analysis of downlink scheduling algorithms through simulations. The scheduling algorithms were simulated using NS-3 and LTE-Sim and various performance factors were studied. Thereafter, a model HetNet was simulated with a macro cell and pico cells. In the simulated LTE network environment, impact of pico cells on macro has been studied along with the scheduling algorithms.
After simulations, a more practical approach has been taken to study the performance of the LTE network. The performance analysis of Proportional Fair (PF) scheduler has been made in the real-time LTE network. In this study, the end users were classified as Gold, Silver and Bronze based on the subscription plans. A combination of various scenarios has been was tested to analyse the throughput of the scheduler. Then the performance of RAN and Evolved Packet Core has been made by observing the Key Performance Indicators (KPIs). To obtain RAN KPIs drive tests were made in various modes such as walking around the city centre, travelling in train, driving in the car and in indoor environments. The KPIs were collected using Nemo Handy RF planning tool. The final part of the thesis covers the performance analysis of EPC. The KPIs such as accessibility, retainability, traffic, mobility, and Automatic Neighbour Relations (ANR) were collected for three months and the EPC performance was analysed. In the analysis, a critical issue in retainability was identified and this issue was impacting the accessibility of the network. After thorough analysis of KPIs, the root cause of the issue was identified as the Mobility Management Entity (MME) sending fake Serving Gateway (SGW) relocation request to eNodeB when there is only one SGW configured. This issue was identified and resolved using the KPIs
