多波束赋形在非正交多址接入技术中的应用研究

Research on the Application of Beamforming in Non⁃orthogonal Multiple Access Technology

为解决非正交多址接入(NOMA)技术在毫米波Massive MIMO系统中用户的分组受限于基站波束宽度的问题,提出了一种能够产生指向多个方向的波束的波束赋形方案.基于该多波束波束赋形方案,建立了多小区多用户场景下的用户资源分配的数学模型.为降低计算的复杂性,采用两阶段的资源分配算法.在第一阶段中,在给定的功率分配条件下将模型转化为联盟博弈中联盟的生成问题,并提出一种通过迭代确定用户分组和天线单元分配的算法;在第二阶段中,通过将非凸的数学优化问题转化为DC规划问题,提出用户功率分配的算法.仿真结果表明,本文所提多波束波束赋形方案能够有效产生指向多个方向的波束,且所提资源分配算法能够有效提高系统的性能.

In order to solve the problem that the user grouping of non⁃orthogonal multiple access(NOMA)in the mm⁃wave massive MIMO system is limited by the beam width of the base station,a beamforming scheme which can gener⁃ate beams pointing in multiple directions is proposed.Based on the multi⁃beam beamforming scheme,a mathematical mod⁃el of user resource allocation in multi⁃cell and multi⁃user scenario is established.In order to reduce the complexity of com⁃putation,a two⁃stage resource allocation algorithm is adopted.In the first stage,under the given power allocation condi⁃tions,the model is transformed into the coalition generation in the coalition game theory,and an algorithm for iteratively de⁃termining user grouping and antenna unit allocation is proposed;in the second stage,an algorithm of user power allocation is proposed by transforming the non⁃convex mathematical optimization problem into a DC programming problem.The sim⁃ulation results show that the proposed multi⁃beam beamforming scheme can effectively generate beams pointing to multiple directions,and the proposed resource allocation algorithm can effectively improve the performance of the system.