| With the development of mobile communication, the demand for wireless communication is increasing, which makes the contradiction between the limited radio resources and the quality of different services severe. To solve this contradiction, OFDMA has become a research hotspot in recent years. Because it can be effectively against multi-path interference, support high-speed data transmission and improve the utilization of spectrum greatly. In order to cope with the challenges of other wireless communication standards such as LTE, IEEE802.16 working group conducts a research on IEEE802.16m standard. Taking OFDMA as the key technology of the IEEE802.16m standard, an evolved version of WiMAX, is a revolutionary technology.IEEE802.16m is one of the 4G standards, whose performance has been further strengthened to meet the demand for a certain aspect of the operator. Since the wireless resources are limited, in order to support as many users as possible and to ensure the quality of service of each user, resource scheduling is an important research topic. Based on the analysis of the IEEE802.16m standard, this paper makes a deep research on the resource scheduling technology in OFDMA IEEE802.16m system.First, this paper studies the three classical resource scheduling algorithm including Round-Robin, Maximum C/I and proportional fair scheduling algorithm, and conducts a simulation to compare their performance in terms of throughput and fairness. Then, in order to improve the system throughput, and ensure the fairness among users, an improved proportional fairness scheduling algorithm is proposed. The simulation results show that improved proportional fairness scheduling algorithm is better than proportional fair scheduling algorithm in terms of system throughput.IEEE802.16m standard defines five different QoS services. Under the multi-service constraints, in order to ensure the quality of different services, utilize resource units efficiently, maximize the throughput of IEEE802.16m OFDMA system, this paper proposes a resource unit allocation scheme with QoS guarantee. First, based on the different services, the different scheduling priorities are defined in the scheme. Then the resource units are pre-allocated to different services and based on the priority of the connection, moderate resource units will be allocated to different connections to satisfy the minimum guaranteed rate of the connection in each service. Finally, the remaining resource units are allocated to each connection to satisfy the maximum transmission rate of the connections with high priority. Simulation results show that the proposed scheme has better performance in terms of the packet loss rate of rtPS service, the packet satisfaction of nrtPS service, the throughput of BE service and the system throughput. |
