本文選題：雙載波超寬帶 + 無(wú)線通信��； 參考：《復(fù)旦大學(xué)》2014年碩士論文

【摘要】：正交頻分復(fù)用OFDM技術(shù)具有極高的頻譜利用率和良好的抗多徑干擾能力,能夠提供高速可靠的通信服務(wù),受到了人們的廣泛關(guān)注,已成為目前新興通信系統(tǒng)的關(guān)鍵技術(shù)和研究熱點(diǎn)。我國(guó)己確定選用基于DC-OFDM技術(shù)的超寬帶技術(shù)作為中國(guó)超寬帶的標(biāo)準(zhǔn),該標(biāo)準(zhǔn)在射頻部分設(shè)計(jì)了雙載波結(jié)構(gòu),使經(jīng)過(guò)基帶處理的信號(hào)分別調(diào)制到兩路不同的載波。這種結(jié)構(gòu)降低了對(duì)射頻和基帶關(guān)鍵電路硬件實(shí)現(xiàn)的要求,獲得了頻域分集效果,提高了頻譜使用的靈活性。在數(shù)字基帶接收機(jī)中,同步器是至關(guān)重要的模塊,其性能好壞直接關(guān)系到系統(tǒng)的性能。同步技術(shù)通常分為符號(hào)同步和頻率同步,符號(hào)同步用于確定OFDM符號(hào)的起始位置,以進(jìn)行快速傅立葉變換操作,正確地實(shí)現(xiàn)數(shù)據(jù)由時(shí)域到頻域的變換。頻率同步的目的是解決發(fā)射機(jī)和接收機(jī)之間由于載波頻率偏移而產(chǎn)生的信號(hào)幅度衰減和子載波信道間干擾的問(wèn)題。本文提出的同步器主要分為三個(gè)部分,第一部分是進(jìn)行符號(hào)同步,主要包括幀檢測(cè)和定時(shí)同步。第二部分是自動(dòng)增益控制,通過(guò)兩級(jí)閉環(huán)控制,準(zhǔn)確估計(jì)一個(gè)前導(dǎo)符的能量并反饋調(diào)節(jié)射頻前端的可變?cè)鲆娣糯笃?使前導(dǎo)符的能量逼近預(yù)先設(shè)置的參考能量。第三部分是頻率同步和IQ失配的估計(jì)補(bǔ)償。在載波頻偏和IQ失配共同作用下,接收信號(hào)出現(xiàn)了幅度下降、子載波間干擾和鏡像子載波干擾,嚴(yán)重影響了接收信號(hào)的質(zhì)量,同步器需要對(duì)這些非理想因素進(jìn)行估計(jì)補(bǔ)償,為后續(xù)數(shù)字信號(hào)處理模塊做好鋪墊。針對(duì)同步器實(shí)現(xiàn)中存在大量的運(yùn)算電路,本文引入了流水線結(jié)構(gòu)的CORDIC算法實(shí)現(xiàn)了反余弦函數(shù)、求根號(hào)函數(shù)和求對(duì)數(shù)函數(shù),大大提高了運(yùn)算速度。對(duì)同步器進(jìn)行了綜合,并根據(jù)綜合結(jié)果進(jìn)行了分析對(duì)比。給出了數(shù)字基帶芯片的后端設(shè)計(jì)、流片及封裝情況,制定了一系列的測(cè)試項(xiàng)目,用于驗(yàn)證芯片及系統(tǒng)的功能,并展示了測(cè)試結(jié)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.
【學(xué)位授予單位】：復(fù)旦大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TN929.53

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 王雪靜;劉亮;葉凡;任俊彥;;適用于OFDM-UWB系統(tǒng)的低復(fù)雜度同步器設(shè)計(jì)[J];通信學(xué)報(bào);2009年01期

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本文編號(hào)：1742353