单频全双工MIMO系统及多用户系统研究

发布时间：2018-11-03 09:17

【摘要】：随着社会经济的发展和无线电技术的进步,各式各样、各种用途的无线电设备大量涌现,各行各业对无线电设备的需求越来越多,频谱资源的紧缺将成为限制无线通信应用和持续发展的瓶颈。因此,如何高效的利用频谱资源成为解决频谱资源短缺的一条途径。本文我们提出利用单频全双工通信和智能天线技术提高频谱的利用率。理论上,单频全双工通信可以提高一倍的频谱利用率。时分双工和频分双工是传统的通信方式。时分双工是半双工的通信模式;频分双工虽然是全双工通信的,但是却使用了两个不同的频段进行通信。本文提出了单频全双工系统,在这个系统中,节点可以在同一个频段同时收发信号。如何有效的消除本地的强自干扰信号是实现全双工通信的关键。我们描述了该系统中使用的自干扰消除机制——天线消除、模拟域消除和数字域消除。我们对该系统进行了仿真。通过仿真研究发现,模拟域自干扰消除的效果会对数字域自干扰消除的效果产生影响,它们之间是此消彼长的关系。如果模拟域消除效果变好,数字域消除的效果就会变差;如果模拟域消除的效果变差,数字域干扰消除的效果就会变好。当模拟域消除和数字域消除的效果达到某个临界点时,整个系统的自干扰消除的效果最佳。另一方面,如果使用智能天线技术,将空间划分成不同的区域,在同一频段传输不同方向的多个信号,这样可以使同一频段得到重复利用,也可以大大提高频谱的利用率。利用智能天线的这一特性,本文提出了一种多用户系统。在该系统中,发送端的多个用户使用不同方向的发射信号发送信息,接收端使用智能天线,利用到达角估计技术估计得到系统中的用户数以及每个用户信号的到达角,然后通过自适应波束成形技术将不同用户的信号恢复出来,从而实现多个用户同时通信。通过仿真研究,我们发现随着信噪比的增大,系统的性能越来越好。通过对三种到达角估计算法和三种自适应波束成形算法准则不同结合的仿真发现,当采用MUSIC到达角估计、最大信干比准则或最小均方误差准则时,系统的性能最佳。
[Abstract]:With the development of society and economy and the progress of radio technology, various kinds of radio equipment are emerging in large numbers, and the demand for radio equipment is increasing in various industries. The shortage of spectrum resources will become the bottleneck to restrict the application and sustainable development of wireless communication. Therefore, how to use spectrum resources efficiently becomes a way to solve the shortage of spectrum resources. In this paper, we propose to improve spectral efficiency by using single-frequency full-duplex communication and smart antenna technology. In theory, single-frequency full-duplex communication can double the spectrum efficiency. Time division duplex and frequency division duplex are traditional communication methods. Time division duplex is a half-duplex communication mode. Although frequency division duplex is full duplex communication, it uses two different frequency bands to communicate. In this paper, a single-frequency full-duplex system is proposed, in which nodes can receive and receive signals simultaneously in the same frequency band. How to effectively eliminate local strong self-interference signal is the key to achieve full duplex communication. We describe the self-interference cancellation mechanisms used in the system-antenna cancellation, analog domain cancellation and digital domain cancellation. We simulated the system. The simulation results show that the effect of self-interference cancellation in analog domain will affect the effect of self-interference cancellation in digital domain, and there is a relationship between them. If the elimination effect of analog domain becomes better, the effect of digital domain elimination will become worse, and if the effect of analog domain elimination becomes worse, the effect of digital domain interference elimination will become better. When the effect of analog domain elimination and digital domain elimination reaches a certain critical point, the whole system has the best self-interference cancellation effect. On the other hand, if the smart antenna technology is used to divide the space into different regions and transmit multiple signals in different directions in the same frequency band, it can reuse the same frequency band and greatly improve the efficiency of the spectrum. Based on this characteristic of smart antenna, a multi-user system is proposed in this paper. In the system, a plurality of users at the transmitter use different directions of transmitting signals to send information, and the receiver uses a smart antenna to estimate the number of users in the system and the arrival angle of each user signal by using the technology of angle of arrival estimation. Then the signals of different users are recovered by adaptive beamforming technology, so that multiple users can communicate at the same time. Through simulation, we find that with the increase of SNR, the performance of the system is getting better and better. The simulation results show that the performance of the system is the best when MUSIC estimation, maximum signal to interference ratio criterion or minimum mean square error criterion are used for the estimation of the angle of arrival and the adaptive beamforming algorithm.
【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】：TN919.3

【共引文献】