| The rapid development of mobile communication makes the services diversified, and it demands a higher requirement on the system bandwidth and the data transfer rate, while the traditional cellular network has been unable to meet the needs of the high speed rate and the high quality of service. The next-generation wireless communication technology standards, such as LTE-A and WiMAX, have introduced the Relay Station to assist the Base Station to complete the data communication. Introducing Relay Station can effectively expand the cell coverage, implove the users’quality of service in the cell edge, and improve the system throughput. Meanwhile, because of the ability of anti-multipath. the improvement of the system spectral efficiency, and the flexible allocation of resources. Orthogonal Frequency Division Multiplexing is treated as the technical basis of the fourth generation mobile communication standard. In this thesis, OFDMA which is based on OFDM is the research foundation.This thesis firstly introduces the basic principles of OFDM/OFDMA, the frame structure of OFDMA, and the classification of RS, then it anlayzes in detail the new problems and challenges on the changing of OFDMA frame structure and resource management after the introduction of RS. Secondly, it anlayzes the global joint optimum allocation algorithm which is baesd on the minimum system power consumption in traditional OFDMA cellular network, as well as various sub-optimization schemes. And the performance of various allocation algorithms can be evaluated through the simulation. Finally, the two-hop link in OFDMA AF relay system is virtualized as a single-hop link, and the optimal global resource allocation algorithm in the traditional OFDMA cellular network is introduced to the relay system, and it can improve the design according to the actual scenarios. The simulation results show that the improved global resource allocation algorithm is more applicable to the actual scene of the relay system, and can effectively improve the energy efficiency and the system throughput while maintaining the fairness of the different users.For the packet scheduling in OFDMA two-hop relay system, this thesis firstly anlayzes the energy efficiency of different modulations and coding schemes for a single user and the occupancy of frequency resources and power resources for a single user, then it uses the analysis results to propose a proportional fair scheduling algorithm based on energy efficiency. This algorithm considers the scheduling priority factor through the maximum delay of the different services during the allocation of resources, the user’s transmission rate is evaluated by the frequency occupancy rate and the power occupancy rate. This scheduling algorithm will use more frequency resources to save the power resources when the system resources are sufficient. When the system resources are tight, the value of the resources is maximized by balancing the occupancy of the resources. Finally, the algorithm proposed in this thesis, the maximum C/I scheduling algorithm and other proposed energy-saving packet scheduling algorithms are simulated and their performances are compared. The simulation results show that in the case of low system load, the proposed algorithm can get the smallest system energy loss under the premise of completing all users’ data transmission, and in the case of high system load, this algorithm can effectively balance the usage of different types of resource in a system while guaranteeing the QoS requirements of different types of service, and ultimately it improves the energy efficiency and the system throughput. |
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