基于MIMO-LTE全双工系统的干扰消除技术研究

发布时间：2018-03-01 16:56

本文关键词： 同频同时全双工天线抵消模拟抵消数字抵消 MIMO LTE　出处：《哈尔滨工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：在无线通信领域,频谱是极其宝贵的资源,然而现行的LTE系统,不是采用频分双工就是采用时分双工的方式,无论哪一种双工方式都不能实现在同一频带内同时发送并接收信号,这样就造成了一半无线频谱资源的浪费。直到同频同时全双工技术的出现才实现真正意义上的全双工通信,然而最近研究发现基于SISO的全双工通信是可以实现的,因此本文主要研究全双工技术应用到基于MIMO-LTE系统中,实现基于MIMO-LTE的全双工系统。然而实现该系统的主要技术难点是:(1)消除本地同频干扰信号;(2)抵消性能受带宽影响;(3)为了动态抵消而调节消扰电路的时间太长。为了解决上述技术难点本文首先分析了干扰信号的各个成份,然后通过设计具体解决方案将干扰信号的各个成份都降到可接受的噪声基底范围内。因此,本文在抵消同频自干扰信号时采用了天线抵消、模拟抵消和数字抵消等多层次联合干扰消除的体系架构,在抵消同频互干扰信号时采用再次使用基于自干扰信号的抵消系统,并通过级联传输函数的方式。最终实现基于MIMO-LTE的全双工系统。本文天线抵消采用的是含有新型环形隔离器的收发同体的天线抵消方式,该方式能够抵消20 dB左右。模拟抵消采用的是N路射频信号通过固定延时器和可编程衰减器后合成一路信号,与自干扰信号对消的方式,其中,可编程衰减器系数采用多维梯度下降算法来计算出来,模拟抵消最高能够抵消50 d B左右。由于干扰信号中包含非线性成份和传输噪声,因此本文又提出了一种新的数字抵消结构,通过采用包含非线性成份和传输噪声的数字基带信号通过线性数字抵消的方式,来进一步的抵消自干扰信号。该方式能够抵消44 d B左右。本文又研究了两种互干扰信号的模拟抵消算法,一种是传统方式的给每个干扰链路都复制自干扰信号的模拟抵消系统。另一种是本文所提出的通过再次使用自干扰信号的模拟抵消系统,并通过级联传输函数的方式。在达到相同的抵消性能的情况下,本文所提出的模拟抵消算法,所使用的总的延时线(包含一个固定延时器和一个可编程的衰减器)的数量比传统的方法要少很多。采用本文提出的互干扰信号的模拟抵消算法,可以减少调节模拟抵消系统的时间。
[Abstract]:In the field of wireless communication, the spectrum is an extremely valuable resource. However, the current LTE systems either use frequency division duplex or time division duplex. Neither duplex mode can transmit and receive signals simultaneously in the same frequency band, which results in the waste of half of the wireless spectrum resources. It is not until the emergence of the same frequency and simultaneous full duplex technology that the true full-duplex communication is realized. However, recent studies have found that full-duplex communication based on SISO can be realized, so this paper mainly studies the application of full-duplex technology to MIMO-LTE based systems. A full-duplex system based on MIMO-LTE is implemented. However, the main technical difficulty in realizing the system is: 1) eliminating the local co-frequency interference signal / / 2) canceling performance is affected by the bandwidth) the time of adjusting the disturbance cancellation circuit for dynamic cancellation is too long. To solve the above technical difficulties, this paper first analyzes the various components of the interference signal. Then, through the design of specific solutions, all components of the interference signal are reduced to the acceptable noise base range. Therefore, in this paper, the antenna is used to cancel the same frequency self-interference signal. The architecture of multi-level joint interference cancellation, such as analog cancellation and digital cancellation, is based on self-interference signal again when cancelling the same frequency mutual interference signal. Finally, the full-duplex system based on MIMO-LTE is realized by cascading transfer function. This method can cancel about 20 dB. The analog cancellation uses the N channel radio frequency signal which is synthesized by fixed delay device and programmable attenuator to cancel the self interference signal. The programmable attenuator coefficient is calculated by the multi-dimensional gradient descent algorithm. The simulated cancellation can cancel the maximum of 50 dB. Because the interference signal contains nonlinear components and transmission noise, In this paper, a new digital cancellation structure is proposed, in which the linear digital cancellation is achieved by using a digital baseband signal containing nonlinear components and transmitting noise. This method can cancel 44 dB or so. In this paper, two kinds of analog cancellation algorithms for mutual interference signals are studied. One is the traditional analog cancellation system that copies the self-interference signal for each interference link, the other is the analog cancellation system proposed in this paper by re-using the self-interference signal. In the case of the same cancellation performance, the simulated cancellation algorithm proposed in this paper is based on cascading transfer functions. The total number of delay lines used (including a fixed delay device and a programmable attenuator) is much smaller than the traditional method. It reduces the time required to adjust the analog counteracting system.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN919.3

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