Research On Radio Resource Allocation Algorithm Of OFDMA System

In the LTE system, due to some new physical layer technologies such as OFDM, MIMO, as well as changes in network architecture, radio resource management is facing many new problems to be solved. for example, dynamic resource allocation problems which is different from the CDMA system, resource utilization fo soft frequency reuse scenarios and so on. On one hand, in the next-generation mobile communication systems which adopt OFDM/SC-FDMA as multiple access technology, the flexibility of resource scheduling will be greatly improved while the business which the systems carry will become more complex. How to design efficient resource allocation scheme to ensure the users'QoS requirements and improve the system spectral efficiency will be key issues of the system, especially for the uplink systems in which the amount of the available information for scheduling is smaller and the scheduling operation procudure is more complex. On the other hand, in the next generation mobile communication systems using OFDMA/SC-FDMA as multiple access technology, the interference condition of the cell edge users will be serious. How to avoid interference while effectively improve the system resource utilization, lower blocking probability of new calls and dropping probability of handover calls, increase system capacity, are all urgent issues to solved.This paper is mainly concerned on the above two problems. In each chapter, we first formulate the problem and analyze the causes of the problem, and then introduce the classical solutions of the similar problems. Finally, the solution strategies of the problem is presented. The main contents of this paper can be summarized as follows:1. The first chapter summarizes the history of mobile communications, introduces the LTE standardization process and the objectives of the system evolution and outlines the traditional radio resource management and the new unsloved problems in radio resource management for the LTE system. 2. The second chapter firstly give an overview of the system-level simulation which includes the static and dynamic system-level simulation methods. Then a further study of the various key modules of the system level simulation is made, including the wireless channel model, the cell topology model, the user distribution model, the user mobility model, the traffic model, the radio resource management module and etc. Finally, the structure of the system-level simulation platform and the overall simulation process is presented with detail.3. The third chapter firstly makes a brief introduction of the LTE uplink system:giving an overview of SC-FDMA and introducing the whole scheduling process of LTE uplink systems. And then the traditional and classical scheduling algorithms are briefly introducted and analyed, which are sorted into schemes for single-cell/single-user systems and schemes for single-cell/multi-user systems. Finally, for the LTE uplink systems, a scheduling scheme is proposed which guarantees the minimum rate required by the user and the performance simulation is conducted.4. The forth chapter firstly makes a brief introduction of the interference suppression techniques, including interference randomization, interference cancellation and interference coordination. Then the traditional and classicl admission control strategies are introduced and compared. Finally, to slove the problems encountered by the traditional admission control strategy which is applied in semi-static soft-frequency reuse scenarios, a joint design of the soft-frequency reuse scheme and the admission control strategy is made. And the performance simulation of the proposed scheme is conducted.Finally, a summarization of the paper is made and the direction of future work is prospected.