Research On Packet Scheduling Algorithm Of Broadband Wireless Communication System

Every one expects the future wireless network can provide QoS guarantees for different applications with the rapid increase of wireless data service and multimedia applications. Therefore, the scheduling algorithms with support of different QoS requirements become the key point of the development of broadband wireless communication networks. OFDM technology, as a high-speed transmission technology for wireless environment, is good at anti-multi path fading. So the thesis mainly provides the research results for different packet scheduling algorithms in fixed broadband wireless access systems.First chapter introduces the scheduling algorithms in wired and wireless networks, including their histories, advantages and disadvantages. The description of scheduling mechanism for standard IEEE802.16-2004 is also included. Second chapter shows the broadband wireless access system simulator on OPNET. It consists of five parts, network model, node model, MAC Layer simulation module, application parameters and PHY Layer parameters. Third chapter provides 3 classical algorithms, weighted Round-Robin (WRR), Max C/I, and Q-PF from Qualcomm. The former two algorithms are simply analyzed. And the Q-PF algorithm is detailed analyzed, such as performance, problems and so on. Chapter 4 presents the LF-PF algorithm. It is the implementation of PF with long frame structure under BWA MAC Layer architecture. And this chapter also proves the consistency of this algorithm with definition of PF. The avoidance of 'Hungry' and advantages compared with Max C/I are analyzed. Chapter 5 shows the JW algorithm. It consists of channel condition, user priority, application priority, delay compensation. It is flexible enough to satisfy different systems and different scenarios. Through the tuning of the four weights, the performance of JW approaches the performance of LF-PF. Its performance of delay and throughput is quite good, and it is easy for control.The last chapter provides the conclusion of the thesis. And it shows the prospect of this field at the end.