Research On Traffic Scheduling Algorithms Based On OFDM Communication Systems

Because orthogonal frequency division multiplexing(OFDM)system can effectively resist frequency selective fading and support high-speed data transmission,it has always been one of the key technologies for Wireless Local Area Network(WLAN)communication system and wireless broadband access system such as Worldwide Interoperability for Microwave Access(WiMAX).This thesis studies the traffic scheduling algorithms for OFDM based WLAN and WiMAX systems.An efficient traffic scheduling algorithm is proposed for the two systems,and then the algorithm is simulated and verified.The results in the thesis can provide an important reference in traffic scheduling algorithms in OFDM-based radio systems.This thesis first introduces the OFDM communication system,the protocol specifications and the technical standards for WLAN and WiMAX systems.Secondly,the cause of congestion in the communication systems and the principle of congestion control are analyzed in detail.Thirdly,we analyze the requirements of the traffic scheduling algorithm suitable for OFDM system,and propose a traffic scheduling algorithm that meets the requirements for WLAN and WiMAX two systems respectively.Fourthly,according to the improved WLAN traffic scheduling based on Random early detection algorithm(RED),we use NS2 as platform in simulations.The results show that our proposed algorithms have improved the network performance in throughput,delay and other parameters.According to the integrated services in WiMAX system,the scheduling algorithms are proposed to meet the quality of service(QoS)requirements.Finally,the thesis is summarized and also foresee the future research directions in traffic scheduling for OFDM based systems.