NOMA系统中利用共轭梯度法的功率分配方案

通过功率分配，5G通信的关键技术——非正交多址（NOMA）实现发射功率域的多用户复用，有效提高了频谱效率。不同的功率分配方案直接影响系统的吞吐量，针对NOMA下行链路现有功率分配算法存在的局部最优问题，提出了一种利用共轭梯度法的最优功率分配方案，采用共轭梯度法求解用户的加权和速率最大化的优化问题。现有理论证明，该方法可以收敛到全局最优解。仿真结果表明，该方法性能优于已有的固定功率分配（FPA）算法和分数阶发射功率分配（FTPA）算法，且此非正交多址（NOMA）系统性能明显优于正交多址（OMA）系统。 

A power allocation scheme based on conjugate gradient method in NOMA system

Non-orthogonal multiple access (NOMA) has become the key technology in 5G communication. NOMA can achieve multi-user multiplexing in transmit power domain by allocating different power, which can effectively improve the system capacity and the spectral efficiency. Different power allocation schemes will directly affect the throughput of the system. Therefore, in order to increase the system capacity, it is necessary to study an effective power allocation scheme. Aiming at the local optimal problem of NOMA downlink power allocation algorithm, an optimal power allocation scheme using conjugate gradient method is proposed， which is used to solve the user's maximum weighted sum rate. The existing theory proves that the conjugate gradient method can converge to the global optimal solution. The simulation results show that its performance is better than fixed power allocation (FPA) algorithm’s and fractional transmit power allocation (FTPA) algorithm’s, and NOMA system with this method is better than orthogonal multiple access (OMA) system.