【作者】 徐鹏；

【导师】 陈亚丁；

【作者基本信息】 电子科技大学 ， 工程硕士（专业学位）， 2019， 硕士

【摘要】 集群通信是按照动态信道指配的方式实现多用户共享信道的无线移动通信系统。随着社会信息化程度的不断提高,集群通信对宽带业务的需求进一步增长,从传统的语音和低速数据传输业务到需要提供视频传输,而且在网络性能上要求更低的网络时延。LTE作为4G和5G标准,其具有的高频谱效率、高速率、低时延等优点,使得基于LTE的宽带集群已成为集群通信宽带化的发展方向。相对于FD-LTE,TD-LTE对于非对称业务的传输具有独特的优势。数字中频技术作为软件无线电技术的重要组成部分,相比于传统的模拟中频,其具有:灵活性高、线性动态范围宽、低漂移、低失真、开发周期短、成本低等优点。而FPGA具有强大的并行计算能力、丰富的片上资源、灵活的开发方式等优势,是当前数字中频技术的主流实现方式。本文首先对数字中频系统进行了详尽的理论和仿真分析。首先根据3GPP协议规范和项目需求,提出了本文数字中频的设计要求。针对关键的滤波模块设计,综合考虑资源消耗、计算复杂度和仿真链路性能等多方面,对比分析了四种不同滤波器设计方案的优劣势,选用了根升余弦滤波器与半带滤波器级联的方案来进行采样率变换和滤波处理,仿真结果验证了方案的有效性,可以满足误差向量幅度、阻带抑制等设计要求。其次,结合相关接口协议,本文对系统涉及的SRIO接口、Aurora接口、ADC/DAC接口和SPI接口,编写了接口模块,实现了接口数据传输,并通过各自的接口测试链路实际检验了接口性能;最后在Vivado中完成了数字中频的模块化设计,并通过16QAM-OFDM链路验证了数字中频模块在系统中的实际性能可满足项目需求;DSP、基带FPGA和中频FPGA作为数据处理单元,配合相关接口,组成TD-LTE集群专网业务测试链路,通过图片业务传输验证了链路性能。更多还原

【Abstract】 Trunked communication is a wireless mobile communication system that implements a multi-user shared channel in a manner of dynamic channel assignment.With the continuous improvement of the degree of social informatization,the demand for broadband services in trunking communication has further increased,from traditional voice and low-speed data transmission services to the need to provide video transmission,and with requirements of lower network delay in network performance.As 4G and 5G standard,LTE has the advantages of higher spectral efficiency,higher data rate,and lower latency,making LTE-based broadband trunked communication the development direction of broadband trunked communication.Compared with FD-LTE,TD-LTE has a unique advantage for the transmission of asymmetric services.As an important part of software radio,digital intermediate frequency has the characteristics of high flexibility,wide linear dynamic range,lower drift,lower distortion,shorter development cycle and lower cost compared with traditional analog intermediate frequency.FPGA has the advantages of powerful parallel computing power,rich on-chip resources,flexible development methods,etc.It is the mainstream implementation method of digital intermediate frequency.This paper firstly carried out detailed theoretical and simulation analysis of the digital intermediate frequency system.Firstly,according to the 3GPP protocol specifications and project requirements,the design requirements of the digital intermediate frequency are proposed.For the key filter module design,considering the resource consumption,computational complexity and simulation link performance,the advantages and disadvantages of four different filter design schemes are compared and analyzed.The root raised cosine filter and the half-band filter are selected.A cascaded scheme is used to perform sample rate conversion and filtering processing.Secondly,according to the relevant interface protocols,this paper writes an interface module for the SRIO interface,Aurora interface,ADC/DAC interface and SPI interface involved in the system,realizes the interface data transmission,and verifies the interface performance through the respective interface test links;Finally,the modular design of digital intermediate frequency is completed in Vivado,and the performance of the digital intermediate frequency module in the system can be verified by the 16QAM-OFDM link.The DSP,baseband FPGA and intermediate frequency FPGA are used as data processing units and related interfaces.The test link of the TD-LTE trunked communication testing system is formed,and the link performance is verified by the picture service transmission.更多还原