基于TD-LTE系统的干扰对齐技术及其在FPGA上的实现
发布时间：2018-12-15 01:42
【摘要】：随着用户业务需求的不断增加,高速率、大容量的通信需求与有限的带宽资源之间的矛盾,推动着通信理念和ICT不断向前发展,MIMO-OFDM技术的出现为解决上述矛盾提供了新的途径。TD-LTE系统在国内大规模商用之后,通信速率和系统容量有了明显提升,其下行链路就采用了MIMO-OFDM技术。然而因其布网时频率复用因子趋近于1,小区内和小区间的同频干扰问题已成为影响通信质量、速率以及系统容量的重要因素。TD-LTE系统小区内的用户受到来自同频小区的干扰以及小区内同频中继节点的干扰,小区边缘的用户受到其他同频小区的基站干扰,针对这些场景下的干扰问题,本文在对比已有的干扰处理方法的基础上,采用了干扰对齐技术,并搭建了基于FPGA的干扰对齐技术验证模型,研究了干扰对齐算法对系统性能提升的影响,得出了相应的结论。论文主要工作如下:1.对TD-LTE系统中的同频干扰的典型场景进行分析总结,结合干扰对齐的相关理论知识,选用了一种易于在FPGA上实现的干扰对齐算法,使之能用于TD-LTE系统中,改善典型干扰场景下的通信质量,提升系统容量;对设计的算法用Matlab进行了仿真,与不采用IA技术的MIMO-OFDM信道进行对比,指出其在系统误码率和容量方面随着信噪比的增大而带来的增益;2.搭建了基于Xilinx FPGA ML605的干扰对齐算法验证硬件平台,在IA算法的FPGA实现过程中,优化了预编码矩阵V和解码矩阵U的求解过程;通过简化FPGA中矩阵求逆运算以及乘法运算,解决了硬件上实现算法时复杂度高而消耗资源过大,系统时延过高的问题;3.提出了一种解决预编码之后待发送数据峰均比过大问题的方法,通过构造调整因子来自适应的对预编码后的数据进行调整,降低峰均比;通过观察板上液晶屏显示以及上位机星座图,验证了采用干扰对齐算法前后的效果,实测表明,干扰对齐技术的应用可以给TD-LTE系统带来实际的增益和性能的改善;4.在上述工作的基础上,进行系统射频部分的开发,以便模拟真实的信道环境来验证干扰对齐技术的效能;运用μSDR420软件无线电平台进行TD-LTE系统MIMO-OFDM下行链路信道环境的开发,最后成功的实现了MIMO-OFDM信道的构建,为以后IA技术在真实无线信道环境下的性能验证提供了条件。本文的研究成果为干扰对齐技术在FPGA上的实现提供了可行方案,为干扰对齐技术在面向未来移动通信演进中的应用提供了参考,为TD-LTE系统的干扰问题提供了一种解决方案,具有现实指导意义。
[Abstract]:With the increasing demand of user service, the contradiction between high speed, large capacity communication demand and limited bandwidth resources promotes the development of communication concept and ICT. The emergence of MIMO-OFDM technology provides a new way to solve the above contradiction. After the large-scale commercial use of TD-LTE system, the communication rate and system capacity have been obviously improved, and MIMO-OFDM technology has been adopted in the downlink of TD-LTE system. However, because the frequency multiplexing factor is approaching 1, the co-frequency interference between the cell and the cell has become a problem affecting the communication quality. The users in the TD-LTE system are interfered by the same frequency cell and the same frequency relay node in the cell, and the users in the edge of the cell are interfered by the base station of other same frequency cell. Aiming at the interference problem in these scenarios, this paper compares the existing interference processing methods, adopts the interference alignment technology, and builds a verification model of interference alignment technology based on FPGA. The effect of interference alignment algorithm on system performance improvement is studied, and the corresponding conclusions are obtained. The main work of this paper is as follows: 1. This paper analyzes and summarizes the typical scenes of the same frequency interference in TD-LTE system, and combines the relevant theoretical knowledge of interference alignment, selects a kind of interference alignment algorithm which is easy to realize on FPGA, so that it can be used in TD-LTE system. Improve the communication quality in the typical jamming scene and enhance the system capacity; The algorithm is simulated by Matlab and compared with the MIMO-OFDM channel without IA technology. The gain of the proposed algorithm is pointed out with the increase of signal-to-noise ratio (SNR) in the system bit error rate (BER) and capacity. 2. The hardware platform of interference alignment algorithm based on Xilinx FPGA ML605 is built. In the FPGA implementation of IA algorithm, the solving process of precoding matrix V and decoding matrix U is optimized. By simplifying matrix inversion and multiplication in FPGA, the problem of high complexity, excessive consumption of resources and high system delay in hardware implementation is solved. 3. A method is proposed to solve the problem that the PAPR of the data to be transmitted after precoding is too large. The PAPR is reduced by constructing the adjustment factor to adjust the precoded data. The results before and after the interference alignment algorithm are verified by the LCD display on the board and the upper computer constellation diagram. The experimental results show that the application of the interference alignment technology can bring the actual gain and performance improvement to the TD-LTE system; 4. Based on the above work, the RF part of the system is developed to simulate the real channel environment to verify the effectiveness of the interference alignment technology. The 渭 SDR420 software radio platform is used to develop the MIMO-OFDM downlink channel environment of TD-LTE system. Finally, the construction of MIMO-OFDM channel is successfully realized, which provides the condition for the future performance verification of IA technology in the real wireless channel environment. The research results of this paper provide a feasible scheme for the implementation of interference alignment technology on FPGA, provide a reference for the application of interference alignment technology in the evolution of mobile communication facing the future, and provide a solution to the interference problem of TD-LTE system. It is of practical significance.
【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
本文编号：2379717
[Abstract]:With the increasing demand of user service, the contradiction between high speed, large capacity communication demand and limited bandwidth resources promotes the development of communication concept and ICT. The emergence of MIMO-OFDM technology provides a new way to solve the above contradiction. After the large-scale commercial use of TD-LTE system, the communication rate and system capacity have been obviously improved, and MIMO-OFDM technology has been adopted in the downlink of TD-LTE system. However, because the frequency multiplexing factor is approaching 1, the co-frequency interference between the cell and the cell has become a problem affecting the communication quality. The users in the TD-LTE system are interfered by the same frequency cell and the same frequency relay node in the cell, and the users in the edge of the cell are interfered by the base station of other same frequency cell. Aiming at the interference problem in these scenarios, this paper compares the existing interference processing methods, adopts the interference alignment technology, and builds a verification model of interference alignment technology based on FPGA. The effect of interference alignment algorithm on system performance improvement is studied, and the corresponding conclusions are obtained. The main work of this paper is as follows: 1. This paper analyzes and summarizes the typical scenes of the same frequency interference in TD-LTE system, and combines the relevant theoretical knowledge of interference alignment, selects a kind of interference alignment algorithm which is easy to realize on FPGA, so that it can be used in TD-LTE system. Improve the communication quality in the typical jamming scene and enhance the system capacity; The algorithm is simulated by Matlab and compared with the MIMO-OFDM channel without IA technology. The gain of the proposed algorithm is pointed out with the increase of signal-to-noise ratio (SNR) in the system bit error rate (BER) and capacity. 2. The hardware platform of interference alignment algorithm based on Xilinx FPGA ML605 is built. In the FPGA implementation of IA algorithm, the solving process of precoding matrix V and decoding matrix U is optimized. By simplifying matrix inversion and multiplication in FPGA, the problem of high complexity, excessive consumption of resources and high system delay in hardware implementation is solved. 3. A method is proposed to solve the problem that the PAPR of the data to be transmitted after precoding is too large. The PAPR is reduced by constructing the adjustment factor to adjust the precoded data. The results before and after the interference alignment algorithm are verified by the LCD display on the board and the upper computer constellation diagram. The experimental results show that the application of the interference alignment technology can bring the actual gain and performance improvement to the TD-LTE system; 4. Based on the above work, the RF part of the system is developed to simulate the real channel environment to verify the effectiveness of the interference alignment technology. The 渭 SDR420 software radio platform is used to develop the MIMO-OFDM downlink channel environment of TD-LTE system. Finally, the construction of MIMO-OFDM channel is successfully realized, which provides the condition for the future performance verification of IA technology in the real wireless channel environment. The research results of this paper provide a feasible scheme for the implementation of interference alignment technology on FPGA, provide a reference for the application of interference alignment technology in the evolution of mobile communication facing the future, and provide a solution to the interference problem of TD-LTE system. It is of practical significance.
【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
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