LTE系统中D2D用户模式选择和功率控制研究

发布时间：2018-03-07 12:22

本文选题：LTE　切入点：D2D通信　出处：《西安电子科技大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着LTE系统的不断演进，移动用户和用户业务需求快速增加，以基站为中心的蜂窝通信系统面临很大的挑战，基站侧的负担也越来越重，频率资源严重不足。为此3GPP把D2D通信（Device to Device）方式引入到LTE系统中，作为LTE系统的一种底层网络增强技术。D2D通信技术可以增加频谱利用率，减轻基站负载，降低用户终端发送功率，从而提升LTE系统的总体容量。由于D2D通信用户工作在LTE系统中，会对LTE系统中原有的用户造成干扰，同时LTE系统的用户也会对D2D通信用户造成影响。本文从模式选择和功率控制两个方面进行研究，以达到降低D2D用户和LTE用户之间的相互干扰，，最大限度地发挥D2D通信技术优势的目的。由于D2D用户有复用模式，专有模式，蜂窝模式三种模式可以选择，D2D用户使用不同模式进行通信，LTE系统性能会有很大区别。为了让D2D用户工作在最佳的模式，最大限度地提高系统性能，本文根据用户通信的实际需求，给对通信要求高的D2D用户设置优先级，优先保证他们的通信质量。在此基础上考虑了基站的负载情况，以频谱效率为评价函数，分别给小区间的D2D通信用户和小区内的D2D通信用户提供两种不同的模式选择方法。仿真结果表明，所提的模式选择方法提高了系统的频谱利用率，降低了用户发送功率。当D2D用户工作在复用模式时，D2D用户和使用相同资源的LTE用户之间会产生严重干扰。为了降低D2D用户和LTE用户之间的相互干扰，本文提出双阈值的功率控制方法。分别给D2D用户和LTE用户的发送功率设置功率控制因子，以最大化D2D用户和LTE用户的吞吐量为优化目标，以两个用户的功率控制因子为优化变量，建立最优化数学模型，求解出最优的功率控制因子，最终得到D2D用户和LTE用户的发送功率。仿真结果表明，所提的双阈值功率控制方法，有效地降低了D2D用户和LTE用户的相互干扰，提升了系统的总体容量。
[Abstract]:With the continuous evolution of LTE system, the demand of mobile users and user services increases rapidly. The cellular communication system centered on the base station faces great challenges, and the burden on the base station side becomes more and more heavy. Therefore, 3GPP introduces D2D communication device to LTE system. As a kind of bottom network enhancement technology of LTE system, D2D communication technology can increase spectrum efficiency and lighten the load of base station. Because D2D communication users work in LTE system, it will interfere with the original users in LTE system. At the same time, the users of LTE system will also have an impact on the D2D communication users. In order to reduce the interference between D2D users and LTE users, this paper studies the mode selection and power control. The purpose of maximizing the advantage of D2D communication technology. Because D2D users have reuse mode, proprietary mode, cellular mode, three modes can choose D2D users to use different modes for communication and LTE system performance will be very different. In order to allow D2D users to work in the best mode, To maximize the performance of the system, according to the actual requirements of user communication, this paper gives priority to D2D users who require high communication, and gives priority to ensure their communication quality. Based on this, the load of base station is considered. Using spectrum efficiency as evaluation function, two different mode selection methods are provided to D2D communication users in the cell and D2D communication users in the cell respectively. The simulation results show that the proposed mode selection method improves the spectrum efficiency of the system. Reduced user transmission power. There is serious interference between D2D users and LTE users using the same resources when D2D users work in multiplexing mode. In order to reduce the interferences between D2D users and LTE users, In this paper, a dual-threshold power control method is proposed. The power control factor is set for the transmission power of D2D users and LTE users, with the aim of maximizing the throughput of D2D users and LTE users. Taking the power control factor of two users as the optimization variable, the optimal mathematical model is established, and the optimal power control factor is solved. Finally, the transmission power of the D2D user and the LTE user is obtained. The simulation results show that, The proposed dual-threshold power control method can effectively reduce the interference between D2D users and LTE users and improve the overall capacity of the system.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.5

【共引文献】