Μελέτη και αξιολόγηση επίδοσης δικτύων WiMAX για την παροχή QoE
SubjectMobile communication systems ; Wireless communication systems ; Broadband communication systems ; Αρχιτεκτονική ηλεκτρονικών υπολογιστών
WiMAX networks provide wireless broadband internet access, interoperability, while decrease the entrance barrier in mobile communications sector, and offer services comparable to those of the emerging 4G technology. However the standard 802.16, upon which WiMAX networks are based, has not designated any particular scheduling algorithm, allowing each provider to develop its own. For this reason several different scheduling algorithms may be found in the literature. This thesis aims to study and develop scheduling algorithms to provide QoE to WiMAX networks. In particular an extensive literature study is carried out on scheduling algorithms and mechanisms to provide QoE to wireless networks. It was observed that the existing scheduling algorithms take into account the QoS, fairness and other parameters, but do not provide QoE. For this reason, in this thesis two different approaches are proposed in order to provide QoE, especially for the rtPS WiMAX service. In the first policy depending on whether there is packet loss the system reduces the transmission rate of each connection, until their minimum allowable transmission rate is achieved. In the second policy the transmission rate of the connection is reduced if its packet loss is greater than a threshold, while in the opposite case the transmission rate is increased. Simulation results show that by applying different levels of MOS the QoE provided to the WiMAX users is improved. However, since there is no scheduling algorithm that can be considered as a panacea, according to the requirements of each user application a different policy should be applied.