Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Evaluation of Scheduling Architectures for Osek/Vdx Compliant Hard Real-Time Operating Systems(Izmir Institute of Technology, 2020) Saydam, Berkay; Ayav, TolgaTechnological advancements are reflected to the vehicles as well, but it brings the challenge of adding new functionalities to vehicles without compromising safety. Tasks are used to provide functionalities which are used in car. These tasks have different characterictics. Safety and performance are two main criteria to determine characterictic of tasks. Characteristics of tasks can be classified according to their safety levels which are known as Automotive Safety Integrity Levels. Designing of hardware and software and also testing them is a long progress in automotive industry. Any changes on the design of hardware is quite costly when an ECU began to be used in field. According to my hypothesis, scheduling algorithms which are used by Central Processing Unit to determine sequences of task executions, should be well known. Besides, designing of hardware and software should be done according to these characteristics and algorithms. If not, tasks will cause serious problem like missing deadline for safety-critical component. In this thesis, the scheduling architectures are evaluated and they are determined which scheduling architectures should be used for which purpose. Besides, the advantages and disadvantages are explained.Master Thesis Performance Enhancement of Real-Time Protocol Master of Science(Izmir Institute of Technology, 2010) Yücel, Çağan Selçuk; Ayav, TolgaA mechanism is described for dynamic adjustment of the performance requirements of multimedia applications. The sending application uses RTP receiver reports to compute packet loss and control mechanism periodically measures the utilization. Based on these and some other metrics the control mechanism can make necessary adjustments. Several experiments have been run in order to tune and evaluate the mechanism. The results indicate that the mechanism can be applied efficiently and the performance of the RTP can be increased.Master Thesis Quality-Adaptive Media Streaming(Izmir Institute of Technology, 2012) Tos, Uras; Ayav, TolgaIn this study, an adaptive method for maximizing network bandwidth utilization for real-time media streaming applications is presented. The proposed method implements a rate control approach over the transport protocol RTP. RTP is coupled with an existing multimedia codec, H.264. A controller that keeps the RTP packet loss fraction at a predefined reference point is implemented. During the course of the stream transmission, the information about the network state is generated by the RTP/RTCP and sent to the server by the clients. Packet loss fraction parameter is fed into the controller. Controlling the multimedia codec bitrate directly affects the packet transmission rate, therefore RTP packet transmission rate is also controlled. Two control approaches are proposed. Firstly, a PID controller is introduced. This PID controller is designed without any self adaptation and manually tuned to maximize all of the available bandwidth. Secondly, a model reference adaptive controller (MRAC) is proposed. This MRAC controller constantly adjusts its parameters according to a reference model. The output of the TCP Friendly Rate Control Algorithm (TFRC) is used as the model to keep the MRAC controller friendly towards other flows flows at a level that the application requires. Simulations are provided to demonstrate the operation of the proposed methods. In the simulations, a content streaming scenario is run against background traffic for the available bandwidth in a bottleneck network configuration.