基于FPGA的线性干扰对齐通信系统的设计与实现

发布时间：2018-03-10 01:03

本文选题：干扰对齐　切入点：OFDM　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】：在无线通信系统中,干扰广泛存在,随着用户数的日益增加,多用户之间的干扰严重限制了通信系统容量,干扰已成为未来无线通信的主要问题之一。传统管理干扰的方法应用于当前密集多用户系统时,单用户频谱效率较低。干扰对齐(Interference Alignment,IA)从干扰重叠这一全新角度来处理多用户之间的干扰,通过预编码技术使干扰在接收端处于有用信号的零空间,彻底消除干扰对期望信号的影响,它是一种有效的干扰管理方法。由于干扰对齐技术需要获知全局信道信息,因此工程实现中必须找到一种降低信道信息反馈量的方法。本文依托国家自然科学基金重点项目“无线网络的干扰管理与容量研究”,在TD-LTE的背景下,提出了干扰对齐链路控制协议以及降低信道信息反馈量的方法,并从工程实现的角度,基于现场可编程门阵列(FPGA),设计与实现了线性干扰对齐OFDM通信系统。首先,通过平衡信道估计准确度与系统传输性能,提出了干扰对齐链路控制协议,并在其中使用了一种降低信道信息反馈量的方法。依据此协议,终端在每一个无线帧开头进行一次频域信道估计,然后将频域信道估计值转换到时域进行反馈,以降低信道信息反馈量。基站广播收到的全局信道估计信息,同时利用该信道信息,求出干扰对齐预编码矩阵,并对当前帧后续发送的有效数据进行预编码处理。终端利用基站广播的全局信道信息求出解码矩阵,对当前帧的有效数据部分解码处理,实现干扰对齐。其次,在理论验证正确的情况下,利用FPGA技术实现了包含线性干扰对齐技术的OFDM基带系统收发模块的设计与编码。通信系统平台采用自顶向下的设计方法,首先设计出系统模块的整体架构图,然后使用Xilinx公司的开发套件ISE14.6和ModelSim仿真软件,通过Verilog硬件描述语言完成各个模块的设计与编码工作。文中重点描述加扰与解扰模块、映射与解映射模块、参考序列分配模块、信道估计及反馈模块、FFT/IFFT模块及外围接口模块的设计思路和实现方法。仿真与运行结果表明,本文设计的包含IA技术的OFDM基带系统的各编解码模块基本满足要求,仿真与硬件测试显示各模块正常工作,整个通信系统基本可以实现3对用户同时通信,验证了本文提出的IA链路交互协议和降低信道信息反馈量方法的可行性。最后对平台的性能进行分析与评估,结果表明平台使用IA技术的吞吐量约为使用传统复用技术的2倍。
[Abstract]:In wireless communication system, interference exists widely. With the increasing number of users, interference between multiple users seriously limits the capacity of communication system. Interference has become one of the main problems in future wireless communication. Single user spectrum efficiency is relatively low. Interference alignment interference alignment (IIA) deals with interference between multiple users from a completely new perspective of interference overlap, making interference in the zero space of a useful signal at the receiving end through precoding techniques. It is an effective interference management method to eliminate the influence of interference on the desired signal completely. Because the interference alignment technology needs to know the global channel information, Therefore, it is necessary to find a way to reduce the channel information feedback in engineering implementation. This paper relies on the key project of National Natural Science Foundation, "interference Management and capacity Research of Wireless Network", under the background of TD-LTE. An interference alignment link control protocol and a method to reduce the channel information feedback are proposed. Based on the field programmable gate array (FPGA), a linear interference aligned OFDM communication system is designed and implemented from the point of view of engineering implementation. By balancing channel estimation accuracy with system transmission performance, an interference alignment link control protocol is proposed, and a method to reduce channel information feedback is used. The terminal performs a frequency domain channel estimation at the beginning of each radio frame, and then converts the frequency domain channel estimation value to time domain for feedback, so as to reduce the channel information feedback.; the base station broadcasts the received global channel estimation information. At the same time, the interference alignment precoding matrix is obtained by using the channel information, and the effective data transmitted by the current frame is precoded. The terminal uses the global channel information broadcast by the base station to obtain the decoding matrix. The effective data part of the current frame is decoded to achieve interference alignment. Secondly, if the theory is correct, The design and coding of the transceiver module of the OFDM baseband system including linear interference alignment technology is realized by using FPGA technology. The communication system platform adopts the top-down design method, and the overall architecture diagram of the system module is designed at first. Then, using ISE14.6 and ModelSim simulation software of Xilinx Company, the design and coding of each module are accomplished by Verilog hardware description language. The scrambling and descrambling module, mapping and descrambling module, reference sequence allocation module are described in this paper. The channel estimation and feedback module FFT / Ifft module and peripheral interface module are designed and implemented. The simulation and operation results show that the OFDM baseband system including IA technology designed in this paper basically meets the requirements of the coding and decoding modules. Simulation and hardware test show that each module works normally, and the whole communication system can basically realize 3 pairs of users to communicate at the same time. Finally, the performance of the platform is analyzed and evaluated. The results show that the throughput of the platform using IA technology is about twice as high as that of traditional multiplexing technology.
【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;TN972

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