多用户MIMO无线网络中的Device-to-Device通信研究

发布时间：2018-04-26 10:41

本文选题：多输入多输出 + 设备对设备通信　；参考：《电子科技大学》2017年硕士论文

【摘要】：随着智能终端的快速普及以及网络通信容量的爆炸式增长,发展无线通信新技术的需求也更加明确及迫切,D2D(Device-to-Device)通信应运而生。D2D通信是指距离较近的用户设备之间利用直连链路直接通信而不必经过基站转发的技术。D2D通信带来的好处有:提升无线频谱资源的利用率以及数据传输速率,减小移动终端的发射功率,延长电池寿命等。但同时D2D通信的存在也使得通信过程中干扰环境变得更为复杂。因此有效地管理用户间干扰及合理地规划用户的通信模式是研究中的一个重要问题。本文研究的场景为在MIMO(Multiple Input Multiple Output)系统中加入D2D通信,D2D通信用户与小区用户共享频谱资源,且拥有相同的优先级。首先研究了与文献[1]相同的问题,用户同时采用基站转发模式与D2D通信模式时,最大化系统和速率。由于MIMO系统中的最大化和速率问题已经被证明为是NP-hard问题,通过引入松弛变量等方式将原问题进行转化,分为两个独立的子问题。基于块坐标下降法设计出迭代算法,在求解一个子问题时,固定另一个子问题中的变量。最后给出了算法的复杂度与收敛性分析,并给出了仿真结果。但在实际应用场景中,存在一些用户对之间距离较远或是直连链路状况较差的情况,因此设计了更加灵活的基于用户模式选择的最大化系统和速率优化算法,联合优化用户通信模式及发送波束成形向量,考虑到过多的D2D用户对带来的反馈信息会增加系统的开销,加入了稀疏优化以限制D2D用户对数。由于原问题不能直接解决,本文中做了一些近似处理后设计了一种迭代更新算法,分成几个子问题交替更新求解。仿真结果说明用户合理地选择通信模式后得到的系统和速率优于单纯的选择基站转发通信或D2D模式通信,并通过与随机选取D2D用户对比说明了算法的有效性。
[Abstract]:With the rapid popularization of intelligent terminals and the explosive growth of network communication capacity, The need of developing new wireless communication technology is also more clear and urgent. D2DD communication is the technology of direct communication using direct link between users with close distance without having to be forwarded through base station. D2D communication is the technology. D2D communication is brought about by the emergence of D2D communication. D2D communication is the technology of direct link communication between user devices that is close to each other without having to be forwarded through base station. The benefits include: improving the utilization of wireless spectrum resources and data transmission rates, Reduce the transmission power of mobile terminal, prolong battery life and so on. But at the same time, the existence of D2D communication also makes the interference environment more complex. Therefore, it is an important problem to manage the interuser interference effectively and to plan the communication mode reasonably. The scenario studied in this paper is to add D2D communication and D2D communication users to the MIMO(Multiple Input Multiple output system to share the spectrum resources with the community users and have the same priority. Firstly, the same problem as that in reference [1] is studied. When the user adopts the base station forwarding mode and the D2D communication mode at the same time, the system and the rate are maximized. Because the maximization and rate problem in MIMO system has been proved to be a NP-hard problem, the original problem is transformed into two independent sub-problems by introducing relaxation variables. An iterative algorithm is designed based on the block coordinate descent method. When solving one subproblem, the variables in the other subproblem are fixed. Finally, the complexity and convergence of the algorithm are analyzed, and the simulation results are given. However, in the practical application scenario, there are some cases where the distance between user pairs is relatively long or the condition of direct link is poor, so a more flexible maximization system and rate optimization algorithm based on user mode selection are designed. In order to optimize the user communication mode and transmit beamforming vector, considering that too many D2D users' feedback information will increase the system overhead, sparse optimization is added to limit the D2D user logarithm. Because the original problem can not be solved directly, an iterative updating algorithm is designed after some approximate processing, which is divided into several sub-problems. The simulation results show that the system and rate obtained by the reasonable selection of the communication mode are superior to those obtained by simply selecting the base station forwarding communication or the D2D mode communication, and the effectiveness of the algorithm is illustrated by comparing with the random selection of D2D users.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN919.3

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