The Research Of Centralized Scheduling In WiMAX Mesh Network

With the rapid development of science and technology and the improvement of people's living standards, the existed low-bandwidth wireless access technologies can no longer meet the growing needs of mobile broadband, so more attention are paid to broadband technologies. WiMAX (Worldwide Interoperability for Microwave Access), which is known as IEEE 802.16, is a broadband wireless access technology. With longer transmission distance, higher transmission rate, lower cost, WiMAX as one of the wireless broadband technologies has good developing prospects. The current scheduling tree construction algorithms of WiMAX MAC (Media Access Control) layer have two main ways such as minimum-hop algorithm, breadth-first search algorithm and the shortest path algorithm. Assignment algorithms of timeslot have centralized scheduling and distribute scheduling. These scheduling algorithms have different applications. The centralized scheduling is for the little mobile and large amount of data transmission, whereas the distribute scheduling is for the large mobile and little data transmission. Different scheduling tree construction algorithms and timeslot assignment algorithms have different influence on the system. How to select these good algorithms has become one of most important focuses of current researches in the field of WiMAX MAC layer. The current scheduling tree construction algorithm simply considers the number of hops, distance, or a combination of both, without considering the number of antennas and buffer which also impact on system performance. Although multi-antenna multi-channel centralized scheduling has been researched, but it lacks of research for nodes in a coordinated manner. It is necessary to conduct in-depth study of the two fields.This paper is proposed to get a better optimization construction of routing tree algorithm and get a better centralized scheduling in the WiMAX Mesh networks.This paper deeps into the research of existed scheduling tree construction algorithms and proposes a self-adapting scheduling algorithm full considering distance, buffer, hops, load balancing and so on to improve the system performance. This paper also proposes tree-based approach centralized scheduling for multi-antenna multi-channel network to reduce delays, increase throughput and concurrent nodes and reduces as much as possible interference to bring up the system performance in certain number of channels and antennas in the case of allocation of time slots.Extensive experimental results show self-adapting scheduling algorithm and tree-based approach centralized scheduling for multi-antenna multi-channel network have decreased the scheduling length and increased channel utilization ratio. Experiments also show that about 3 to 4 of channel number will be able to coordinate well the transmission of neighboring nodes in the single-antenna multi-channel network. The experiments also examine the number of antenna impacting on the system and get the corresponding conclusions.