Research On Radio Resource Allocation For Next Genearation Mobile Communication Systems

Orthogonal Frequency Division Multiplexing (OFDM) is a recommended technology for the next generation mobile communication systems. And cognitive radio technology is also paid more and more attention by many researchers for its high spectrum efficiency. So we do some research works about the resource allocations for cognitive radio systems based on OFDM in theory and practical applications.In this paper, firstly a brief introduction of the basic knowledge about the next generation mobile communication systems and cognitive radio. Then, a typical model of cognitve radio system based on OFDM is proposed. In the following, several algorithms are proposed to improve the performance in the cognitve radio systems based on OFDM, and the performance analysis in theory is deduced for it.The works in the paper are summarized as following:1. Two resource allocation algorithms for cognitive radio systems are proposed-the spectrum hole algorithm and the protecting radius algorithm. The algorithms include the allocation algorithms for subcarriers and power. The subcarrier allocation algorithm based on the user's transmission rate ensures that each user can access the CR system. The power allocation algorithm can allocate the subcarriers to the proper users by the spectrum detecting, and it makes the total transmit power of the CR base station reduced significantly.2. An algorithm for cognitive radio systems is proposed to maximum the total transmission rate, when the total transmit power is limited. The proposed algorithm is a joint alloction algorithm for subcarriers and power, and the optimal allocation leeds to the maximal transmission rate.The proposed algorithms in this paper can improve the performanceof the cognitive radio system, with conveniency and low complexity. Andit is substantial for the real cognitive radio system.