Study Of Dynamic Resource Allocation Algorithm In Multiuser OFDM System And Its Application

The dynamic resource allocation algorithm in multiuser Orthogonal Frequency Division Multiplexing (OFDM) system is studied in this paper. Initially, fundamentals of OFDM and technologies of cognitive radio are introduced in this paper. The adaptive power allocation algorithm and modulation scheme for adaptive OFDM systems are studied subsequently. Afterwards, dynamic resource allocation schemes for multiuser OFDM systems are studied in depth. A novel resource allocation algorithm which considers the system capacity and fairness jointly is proposed in this paper. The proposed algorithm can optimize the system performance in both the time and frequency domains by choosing the access time for each user appropriately based on the real-time Channel State Information (CSI) and the requirement of data rate. Simulation results indicate that the proposed algorithm can not only guarantee the fairness among users, but also improve the spectral efficiency efficiently without increasing the algorithm complexity. In addition, a cross-layer resource allocation scheme based on WRAN is investigated. According to related definitions on PHY and MAC layer in the WRAN environment, a cross-layer resource scheduling scheme is proposed. Simulation results indicate that the algorithm can improve the system capacity on the basis of requirements of QoS and users'transmission rate.