Research On Resource Management And QoS Mechanism Of WiMAX Network

WiMAX network is a high-speed broadband wireless network based on IEEE802.16 serial standards,which is known as one kind of WMAN,with long transmission distance,high transmission rate,connection-oriented and QoS(Quality of Service)support,etc.WiMAX-2based on IEEE802.16 m standard is ITU approved 4G standards.WiMAX-Advanced standards are integrated with LTE technology in the 5G network.IEEE802.16 serial standards and drafts mainly focus on the related issues with MAC layer and PHY layer.It defines network basic framework,hierarchical structure,frame structure,bridge and network management,mobility,multi-hop relay and other primary features in WiMAX network.In the standards of IEEE802.16,the slot allocation and reservation mechanism of OFDM frame,QoS management and scheduling optimization are regarded as open question for users to solve their own,which makes the problems becoming researching hotspots.The main contents of the dissertation are to research and analyze the slot allocation algorithms and bandwidth allocation algorithms with QoS supported,and put forward new solutions.An effective downlink resource allocation scheme is proposed for the physical frames in WIMAX network using adaptive modulation and coding(AMC)mode and orthogonal frequency division multiple access(OFDMA)technology.Given a set of Subscriber Station(SS)requests,the modulation and coding scheme is determined from top to down level according to the algorithm,and a two-dimensional rectangular slot block is allocated for each burst in wider range aiming at fragment optimization.After detailed description and simulation analysis for the proposed heuristic resource allocation scheme,the result shows the new scheme is better in channel utilization and system throughput at the same time,compared with classical downlink bandwidth allocation algorithm(EDBA).A competition model of the uplink channel is given.The principle and idea of the dynamic allocation algorithm based on the measurable parameters(collision probability)to control the controllable parameters(the number of competing time slots)are explained.In order to improve the efficiency of resource use,the uplink competing time slots are divided into ranging group and bandwidth request group by IEEE802.16 standards,and each group is shared by multiple users for a specific type of data transmission.After the analysis and calculation,chapter 4 gives a static competition model of the uplink channel,and then obtains the principle and idea of the dynamic allocation algorithm that describes the relation between the collision probability and the number of competing time slots.The simulation proves the feasibility and validity of the dynamic algorithm.The related parameters of dynamic allocation algorithm are also analyzed and discussed.Based on the analysis of scheduling tree construction algorithm of centralized mesh network,a dynamic minimum conflict scheduling tree construction algorithm and QoS scheduling algorithm are proposed.The new scheduling tree construction algorithm can reduce the mutual interference between the scheduling tree paths and improve the concurrency of data transmission.At the same time,the QoS scheduling algorithm of BS is researched,and the idea of utility optimization is applied to QoS service guarantee mechanism in WIMAX centralized mesh network.The mechanism of bandwidth request and grant is described and the utility function is designed.The QoS scheduling algorithm can guarantee the QoS of traffics and improve the system throughput.In order to improve the usage utility of minislots,chapter 6 proposes a minislots allocation algorithm LS(Longest Segment)based on the optimal allocation model for data subframe of TDMA-based distributed mesh network.To achieve accurate realization of minislots allocation,reduce the number of discrete minislots windows and reach the goal of as much as possible continuous distribution minislots.The LS algorithm design the concept of segment,and allocate minislots based on longest segment.The algorithm analysis and simulation are implemented,the result shows that the algorithm has the higher minislots utilization and the lower packet transmission delay.