NOMA下行信道总速率最大化算法研究

Research on the Algorithm to Maximize the Sum Rate of NOMA Downlink

非正交多址接入(Non-Orthogonal Multiple Access,NOMA)技术是第五代移动通信的关键技术,通过采用叠加编码技术在很大程度上提高了信道的频谱效率。但是,在同一信道上叠加所有用户会造成较大的解码时延与错误传播。研究NOMA下行信道的用户选择问题,将基站的发射功率和单个信道叠加的用户数量作为约束条件,提出了基于贪婪策略的用户选择算法,该算法能够在多项式时间内求得问题的近似最优解。进一步提出了一种基于分支限界的用户选择算法,以贪婪解为下界,局部最优解为上界,可以达到最优系统总速率。仿真结果表明,提出的基于分支限界的用户选择算法与传统算法相比可以得到NOMA下行信道最大总速率,并且有效降低了用户选择的时间复杂度。

Non-orthogonal multiple access(NOMA)technology is the key technology of the fifth generation mobile communication,and the spectral efficiency of the channel is greatly improved by using superposition coding technology.However,superimposing all users on the same channel will cause large decoding delay and error propagation.In this paper,the user selection problem of NOMA downlink channel is studied.Taking the transmit power of the base station and the number of users superimposed on a single channel as constraints,a user selection algorithm based on greedy strategy is proposed,which can obtain the approximate optimal solution of the problem in polynomial time.Furthermore,this paper proposes a user selection algorithm based on branch and bound,which takes the greedy solution as the lower bound and the local optimal solution as the upper bound to achieve the optimal total system rate.The simulation results show that compared with the traditional algorithm,the user selection algorithm based on branch and bound proposed in this paper can obtain the maximum total rate of NOMA downlink channel,and effectively reduce the time complexity of user selection.