| With the rapid development of modern communications technology, people voice, video, data and other various needs continue to grow. At present the core network construction has been of considerable size, has a great capacity to meet the social development of the information transmission requirements, while the prominent contradictions and some of the access network, so a variety of broadband access technologies into the current communications sector is concerned focus. As Broadband Wireless Access technology has the flexibility, convenience, mobility and the apparent advantages of low investment, so more and more industry-wide attention amony the broadband access technologies.The Wimax is based on the IEEE 802.16 standard for wireless MAN technology and the new direction for broadband multimedia services in wireless MAN. WiMAX to achieve real-time vehicle speed multimedia services as the goal, to achieve longer transmiss ion distance, providing more high-speed broadband access and multimedia communications services. But as a real-time multimedia services for mobile and broadband access systems, how to ensure good service quality is the core problem.Current research on the Wimax network is still in its infancy, the IEEE 802.16 standard part of network access control and bandwidth allocation are not part of a concrete definition. So how Wimax network for data flow in the different types of analysis, how to set up Wimax different connection modes in the bandwidth allocation model, how the design of appropriate bandwidth allocation algorithm, to optimize network design task as the current Wimax network of the main problems facing the implementation of. Efforts of the thesis as follow:(1) First introduction IEEE 802.16 series of protocols combined, Wimax wireless broadband access applications, and analyze Wimax MAC layer of the three main sub-layer, The last based on the five business flow in Wimax and business flow of the corresponding bandwidth request mechanisms and grant mechanism.(2) Divided into two categories separately wired and wireless bandwidth, bandwidth scheduling algorithm scheduling algorithms were compared. Cable Bandwidth scheduling algorithm which include: FIFO, Static Priority Algorithm, Round Robin Scheduling Algorithm and GPS, wireless bandwidth scheduling algorithms include: CSDPS algorithm, IWFQ algorithm, CIF-Q algorithm. Finally analysis bandwidth scheduling in Wimax PMP mode framework.(3) Based on The adaptive coding when the network abnormal state at the expense of data rates for data traffic, through the introduction of slot polling and queue fair function, to ensure the fairness algorithm and system throughput.(4) Finally built NS-2 platform on the proposed simulation algorithm, and with the Absolute Priority Scheduling Algorithm for performance comparison and analysis of the performance of the algorithm. |
