| With the rapid development of wireless communication services, especially high rate data services, spectrum resources and energy, as non-renewable resources become increasingly scarce. Due to the orthogonality amomg subcarriers and the ability of good resistance to multipath interference of Orthogonal frequency Division multiplexing(OFDM) technology, Orthogonal Frequency Division Multiple Access(OFDMA) can improve the system spectrum utilization, which is as a kind of advanced multiple access technology. These features make the resource allocation of OFDMA system more flexible and efficient. This article is based on OFDMA system, in view of the problem of how to improve spectrum efficiency and energy efficiency of resource allocation, the specific work is as follows:Firstly, through the study of the typical Shen algorithm and the traditional proportional fair resource allocation algorithm and the analysis of this two algorithms in the inadequate use of different fading of the subcarrier for different users, this chapter puts forward a balanced subcarrier allocation algorithm. When allocating subcarrier for the minimum percentage rate users, the subcarrier will be compared. if the throughput gets increase, the balanced allocation algorithm will be adopted, otherwise, the original allocation algorithm will be adopted. Through the simulation prove that, the proposed algorithm can effectively improve the system throughput under the condition of without increasing the complexity of algorithm.Secondly, in view of the resource allocation problem often only focus on the spectrum efficiency and neglect the problem of energy efficiency in the past, this chapter puts forward a kind of dichotomy power allocation algorithm based on energy efficiency.First, the balanced subcarrier allocation algorithm is adopted to allocate subcarriers allocation for users, and then we solve the optimization problem using the method of bisection. The simulation results show that the algorithm can improve the system efficiency, as well as guarantee system throughput without loss.Finally, in view of the heterogeneous network, two-tier femtocell networks can’t make the best use of interference threshold of the macrocell users, this chapter putsforward a power allocation algorithm for achieving high energy efficiency in two-tier femtocell networks based on maximize the efficiency of power utilization.This algorithm make femto cellular users share more effective power under the condition of interference threshold of the macrocell users,improving the energy efficiency of femto cellular users.The simulation results show that the algorithm can effectively improve the energy efficiency of femto cellular,while guaranting the throughput. |
