基于FPGA的xDSL信道模拟器设计与实现

发布时间：2018-04-27 07:30

本文选题：xDSL信道 + 传输线模型　；参考：《电子科技大学》2017年硕士论文

【摘要】：随着数字用户线路技术(Digital Subscriber Line,DSL)的发展,以VDSL2、G.fast等为代表的xDSL技术,在充分运用已铺设铜线资源的条件下,可提供与无源光纤网相近的通信带宽,并大幅降低宽带网络投资。同时,随着用户对宽带通信质量要求的提高,宽带通信设备的研发也变得越来越复杂,设备厂商的系统测试环节在整个设备研发过程中所占的比重也随之增大。为了缩减开发周期和保证设备质量,设备检验员急需在实验室环境下还原出宽带有线信道的传输特征,用以对开发的通讯设备开展测验评估。伴随多业务、高带宽、串扰等DSL宽带通信新特征的产生,传统的信道模拟方案已经不能满足当前宽带通信设备的测试需求。基于此,本文实现了一种基于FPGA的xDSL信道模拟器,其具有频谱范围广、升级难度低、扩展性能好等优点,可在DSL通讯设备测验中发挥重要作用。本文设计的xDSL信道模拟器使用Xilinx公司的Virtex-7系列芯片实现了8线对双绞线信道的上下行模拟。从xDSL信道的传输特性出发,分析了xDSL信道的传输模型和影响信道传输的主要参数,重点分析了信道的远端衰减特性和远端串扰特性,实现了基于FPGA的xDSL信道模拟器,并进行了测试验证。首先,本文研究了xDSL信道的传输特性,对xDSL信道的理论模型进行深入分析,着重分析了DSL传输信道的远端衰减特性和远端串扰特性。其次,分析了基于FPGA的xDSL信道模拟系统的总体架构,对信道模拟器的硬件结构进行了分析,提出了一种基于FPGA的xDSL信道模拟方案。针对FPGA内部资源分配,分析了xDSL信道模拟器FPGA实现过程中的难点,划分了主要功能模块。主要完成了数据采集、信号检测、远端衰减、片间互连、远端串扰、UDP通信等模块的代码开发和板上调试;分析了模拟器的控制通信协议,并编写了PC端交互软件;完成了8线对xDSL传输模拟器与PC后台界面的联合调试。最后,对xDSL信道模拟器进行系统测试,利用xDSL局端和远端设备对不同传输带宽和不同传输距离下的信道特性进行实际测试,即在信道的各传输路径上测试其上下行的信噪比、传输速率等参数,测试结果符合规定的参数要求。
[Abstract]:With the development of Digital Subscriber Line (DSL), the xDSL technology, such as VDSL2G. Fast and so on, can provide the communication bandwidth close to that of passive optical fiber network under the condition of fully utilizing copper wire resources, and greatly reduce the investment in broadband network. At the same time, with the improvement of broadband communication quality, the research and development of broadband communication equipment is becoming more and more complex, and the proportion of system testing of equipment manufacturers in the whole process of equipment development is also increasing. In order to reduce the development cycle and ensure the quality of the equipment, the equipment inspectors urgently need to restore the transmission characteristics of the wideband wired channel in the laboratory environment, which can be used to test and evaluate the communication equipment developed. With the emergence of new features of DSL broadband communication such as multi-service, high-bandwidth and crosstalk, the traditional channel simulation scheme can no longer meet the test requirements of current broadband communication equipment. Based on this, this paper implements a xDSL channel simulator based on FPGA, which has the advantages of wide spectrum range, low difficulty in upgrading and good expansion performance. It can play an important role in the test of DSL communication equipment. The xDSL channel simulator designed in this paper uses the Virtex-7 series chips of Xilinx Company to realize the uplink and downlink simulation of 8-wire pair twisted-pair channel. Based on the transmission characteristics of xDSL channel, the transmission model of xDSL channel and the main parameters affecting the channel transmission are analyzed. The remote attenuation and crosstalk characteristics of the channel are analyzed, and the xDSL channel simulator based on FPGA is realized. The test and verification are carried out. Firstly, the transmission characteristics of xDSL channel are studied in this paper. The theoretical model of xDSL channel is analyzed in depth, and the remote attenuation and crosstalk characteristics of DSL transmission channel are emphatically analyzed. Secondly, the overall architecture of xDSL channel simulation system based on FPGA is analyzed, the hardware structure of channel simulator is analyzed, and a xDSL channel simulation scheme based on FPGA is proposed. According to the internal resource allocation of FPGA, the difficulties in FPGA implementation of xDSL channel simulator are analyzed, and the main function modules are divided. The code development and on-board debugging of data acquisition, signal detection, remote attenuation, interconnect between chips, remote crosstalk UDP communication are accomplished, and the control communication protocol of simulator is analyzed, and the interactive software of PC is written. The 8-line xDSL transmission simulator and PC background interface are debugged. Finally, the xDSL channel simulator is tested systematically, and the channel characteristics under different transmission bandwidth and different transmission distance are tested by using the xDSL terminal and remote equipment, that is, the signal to noise ratio (SNR) of the channel is tested on each transmission path of the channel. Transmission rate and other parameters, the test results meet the requirements of the specified parameters.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN915.6

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