Research On Joint Resource Allocation Algorithms In OFDMA Systems

In the future broadband wireless communication systems, it existed two most critical challenges: multipath fading channel and frequency efficiency. Orthogonal frequency division multiplexing (OFDM) technology had enormous advantage in the anti-multipath fading and high-speed transmission, it made the technology as a key technology of the fourth-generation mobile technology. Orthogonal frequency division multiple access (OFDMA) based on OFDM also became a research point in wireless access technology research. Therefore, the research of resource allocation based on OFDMA became as a hot topic in the study of the current fourth-generation mobile communications.The available resources of wireless communications systems are mainly frequency resources and power resources. Resource allocation algorithm is to make rational use of these resources, according to the optimized object to achieve throughput purpose or to meet Quality of Service (QoS) requirements. Joint resource allocation algorithm takes into account the distribution of subchannels and the distribution of power in the process of resources allocation.The paper firstly introduced the research background and the relative technologies of OFDM, and then it briefly introduced the design of OFDM system-level simulation platform. Next in the third and fourth chapters of this paper discussed in detail the major work completed, the paper mainly researchs on adaptive resource allocation algorithms in the single-cell (single base station) and multi-cell (multi base station) systems. In the third chapter, the paper firstly introduced several classic single-cell algorithms, and then it proposed a new resource allocation algorithm to meet the QoS requirements in multi-user multi-traffic systems. The algorithm mainly built the cost functions according to its own requirement based on the QoS requirements of different traffic. Simulation results showed that the algorithm can meet users' QoS requiremnts of different traffics.In the fourth chapter, the paper mainly researched resource allocation algorithm in OFDMA multi-cell system. The fairness of the performance is one of the most important indicators in the multi-cell system. Based on in-depth study of the current several common algorithms, the paper proposed a new multi-cell joint resource allocation algorithm to improve the fairness performance. The algorithm used the theorem of the inequality mean, and the difference of signal to interference plus noise ratio (SINR), to coordinate the interference of the co-subchannels of adjacent cells. The algorithm could improve the fairness of the performance, and ensure the throughput of the system. Subsequently, taking into account the actual applications to the algorithm, the paper proposed a simplifying approximation. The simplified algorithm could greatly reducd the volume of the feedback system and the complexity of the algorithm. The simulation results show that these two algorithms have improved the fairness of the system.