Research On Resource Allocation Algorithm Of OFDMA System In LTE-A

In recent years, with the rapid development of LTE-A, the increasing demand for transmission rate, spectrum resources become increasingly scarce and valuable. However, the high energy consumption of the communication system is rapidly increasing at the same time of its high speed development. it causes the waste of resources and environmental pollution,which affects the survival of the human environment. Therefore, the reasonable allocation of resources to solve the problem of spectrum resources shortage and high energy consumption in the communication system has become a double challenge for the development of the communication industry. OFDMA is one of the key technologies of LTE-A physical layer, it has high research value. In this paper, we mainly study the problem of resource allocation in OFDMA system.First of all, the paper introduces the components of the LTE-A network architecture and their respective functions, the concept and basic method of wireless resource management.Secondly, it introduces the basic principles and advantages and disadvantages of OFDMA technology, and describes the physical resource unit, frame structure and slot structure of LTE-A down link transmission in detail.Then, the content of resource allocation in OFDMA system is studied, and the classical algorithm is studied in detail, and proposing a low complexity resource allocation algorithm of rate proportional fairness conditions, Compared with the Shen algorithm, it reduces the complexity of the system and expand the application scenarios of the system in the premise of ensuring the fairness and system capacity. Firstly the algorithm will be strictly proportional to the user rate as the proportion of user to the number of sub carriers. Then, the function expression of power allocation is reconstructed, the function is simplified to a linear function by the proportional relation of the sub carrier number. Finally, the power is obtained by solving the linear function.Finally, the content of OFDMA system resource allocation based on energy efficiency isstudied, and proposed the allocation algorithm of the rate proportional fairness of the user based on energy efficiency, it can ensure the fairness of users and improve the energy efficiency of the system effectively. Firstly, in this algorithm, the sub carrier allocation for each user is carried out under the assumption that the power of each sub carrier is equal to the power. Then, we get the functional relationship between the each user waterline that satisfy the condition of the rate proportional fairness. Then, the user and system rate requirements are used as constraints, and using the dichotomy to solve the function and getting the user waterline under the optimal energy efficiency. Finally, carrying out power allocation according to the user waterline.