Research On Power Allocation In Non-Orthogonal Multiple Access

With the continuous expansion of network volume, enhancing the capacity of mobile wireless communication systems has become increasingly demanding. In the4G era, the development of new mobile communication system multiple-access technology is imperative, and the study of the wireless multiple-access technology will be focused on in the next generation of wireless network technology. Non-orthogonal multiple access technology (NOMA) uses power to distinguish between users. In power multiple access technology, users can transmit signal in the same frequency or time block, greatly improving the system capacity. However, the power division multiple access system greatly depends on the channel condition estimation, channel coding and intelligent detection technology, so it is inconvenience utilized alone. Given these characteristics, this article will be based on the power NOMA division multiple access, from both respects of the transmitter and receiver, through the use of or in combination with other techniques to achieve optimal system performance, the specific research contents and results are as follows:First, this paper combines constellation rotation modulation technology with power NOMA division multiple access. At the transmitting end, constellation rotation superimposed modulation technique combined the power division multiple access system is discussed, to improve the power control factor implemented by channel impact system performance floating, and at the receiving end with the interference cancellation MMSE-SIC algorithm combines the power allocation factor to further improve system performance. Through a large number of simulation experiments, the system in higher SNR region can achieve good performance.Secondly, the different strategies of the power allocation scheme at transmitter are discussed. This paper focuses on the system capacity comparison algorithm based on proportional fairness (PF) power allocation scheme with equal power allocation scheme. The simulation results can show that in the proportional fairness (PF) power allocation algorithm can get better tradeoff between overall system throughput and cell edge user average throughput.Finally, this paper discusses a receiver joint detection algorithms based on the DS evidence theory to solve-the problems caused by MMSE-SIC error propagation which causes a drop in performance when the power distribution are closer. Simulation data of different parameters can be seen that when the difference between the users’power allocation is smaller, the joint detection algorithm based on DS evidence theory can achieve better performance in almost all sections of the received signal to noise ratio than traditional serial interference cancellation algorithm.Considering the above discussion that takes both system complexity and performance in consideration, the schemes proposed and discussed in this paper have practical significance.