双载波超宽带接收机关键技术与基带芯片的实现研究

发布时间：2018-04-13 01:33

本文选题：双载波超宽带 + 无线通信　；参考：《复旦大学》2014年硕士论文

【摘要】：正交频分复用OFDM技术具有极高的频谱利用率和良好的抗多径干扰能力,能够提供高速可靠的通信服务,受到了人们的广泛关注,已成为目前新兴通信系统的关键技术和研究热点。我国己确定选用基于DC-OFDM技术的超宽带技术作为中国超宽带的标准,该标准在射频部分设计了双载波结构,使经过基带处理的信号分别调制到两路不同的载波。这种结构降低了对射频和基带关键电路硬件实现的要求,获得了频域分集效果,提高了频谱使用的灵活性。在数字基带接收机中,同步器是至关重要的模块,其性能好坏直接关系到系统的性能。同步技术通常分为符号同步和频率同步,符号同步用于确定OFDM符号的起始位置,以进行快速傅立叶变换操作,正确地实现数据由时域到频域的变换。频率同步的目的是解决发射机和接收机之间由于载波频率偏移而产生的信号幅度衰减和子载波信道间干扰的问题。本文提出的同步器主要分为三个部分,第一部分是进行符号同步,主要包括帧检测和定时同步。第二部分是自动增益控制,通过两级闭环控制,准确估计一个前导符的能量并反馈调节射频前端的可变增益放大器,使前导符的能量逼近预先设置的参考能量。第三部分是频率同步和IQ失配的估计补偿。在载波频偏和IQ失配共同作用下,接收信号出现了幅度下降、子载波间干扰和镜像子载波干扰,严重影响了接收信号的质量,同步器需要对这些非理想因素进行估计补偿,为后续数字信号处理模块做好铺垫。针对同步器实现中存在大量的运算电路,本文引入了流水线结构的CORDIC算法实现了反余弦函数、求根号函数和求对数函数,大大提高了运算速度。对同步器进行了综合,并根据综合结果进行了分析对比。给出了数字基带芯片的后端设计、流片及封装情况,制定了一系列的测试项目,用于验证芯片及系统的功能,并展示了测试结果。
[Abstract]:Orthogonal Frequency Division Multiplexing (OFDM) technology, which has high spectrum efficiency and good anti-multipath interference ability, can provide high speed and reliable communication service.It has become the key technology and research hotspot of the emerging communication system.In China, UWB technology based on DC-OFDM technology has been chosen as the standard of UWB in China. The dual-carrier structure is designed in the RF part of the standard, so that the baseband signal is modulated to two different carriers.This structure reduces the requirements for RF and baseband hardware implementation, achieves diversity effect in frequency domain, and improves the flexibility of spectrum usage.Synchronizer is a very important module in digital baseband receiver, and its performance is directly related to the performance of the system.The synchronization technique is usually divided into symbol synchronization and frequency synchronization. Symbol synchronization is used to determine the starting position of OFDM symbols to perform fast Fourier transform (FFT) operations and to correctly realize the data conversion from time domain to frequency domain.The purpose of frequency synchronization is to solve the problem of signal amplitude attenuation and interference between subcarriers caused by carrier frequency offset between transmitter and receiver.The proposed synchronizer is divided into three parts. The first part is symbol synchronization, including frame detection and timing synchronization.The second part is the automatic gain control, which estimates the energy of a preamble accurately and adjusts the variable gain amplifier of the RF front end by means of two-stage closed-loop control, so that the energy of the preamble approximates the pre-set reference energy.The third part is the estimation compensation of frequency synchronization and IQ mismatch.Under the combined action of carrier frequency offset and IQ mismatch, the amplitude of the received signal decreases, and the inter-subcarrier interference and mirror sub-carrier interference seriously affect the quality of the received signal. The synchronizer needs to estimate and compensate these non-ideal factors.For the subsequent digital signal processing module to do a good job.In view of the existence of a large number of operational circuits in the implementation of the synchronizer, this paper introduces the CORDIC algorithm of pipeline structure to realize the inverse cosine function, the root sign function and the logarithmic function, which greatly improves the operation speed.The Synchronizer is synthesized, and the results are analyzed and compared.The backend design, streaming chip and encapsulation of digital baseband chip are given. A series of test items are developed to verify the function of the chip and the system, and the test results are presented.
【学位授予单位】：复旦大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.53

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