發(fā)布時(shí)間：2018-11-09 11:56

【摘要】：伴隨著對海洋開發(fā)和利用的深入,人們對于海洋聲通信的可靠性和速率提出了更高的要求。但受限于海洋信道的復(fù)雜特性,如何實(shí)現(xiàn)高速可靠的水聲通信是一大挑戰(zhàn)。 Chirp信號同時(shí)在時(shí)域和頻域進(jìn)行擴(kuò)展,在水下通信過程中具有良好的抗頻率選擇性衰落和抗多普勒頻移的特性。分?jǐn)?shù)階Fourier變換作為一種以Chirp信號為核函數(shù)的時(shí)頻變換,在對Chirp信號的檢測和參數(shù)估計(jì)上有不可替代的優(yōu)勢。論文首先研究了基于分?jǐn)?shù)階Fourier變換的多分量Chirp信號的檢測方法,并在此基礎(chǔ)上結(jié)合二進(jìn)制鍵控,設(shè)計(jì)了多載波Chirp擴(kuò)頻系統(tǒng)。為解決在有限的水聲通信帶寬內(nèi)提升多載波Chirp擴(kuò)頻系統(tǒng)速率的難題,結(jié)合并行組合擴(kuò)頻技術(shù)提出了并行組合Chirp擴(kuò)頻系統(tǒng),并使用單陣元時(shí)間反轉(zhuǎn)鏡技術(shù)作為通信系統(tǒng)的抗碼間干擾的技術(shù)。上述兩個(gè)系統(tǒng)分別在廈門大學(xué)實(shí)驗(yàn)水池及廈門港附近海域進(jìn)行了實(shí)驗(yàn)。結(jié)果表明,論文所提出的兩個(gè)通信系統(tǒng)在特定的水下環(huán)境中,具備高速和可靠的通信的能力。 本文的主要工作概括如下： 1.介紹了國內(nèi)外Chirp水聲通信的研究現(xiàn)狀,及海洋聲信道的特性,分析了信道對通信系統(tǒng)的影響； 2.利用Chirp信號在分?jǐn)?shù)階Fourier變換域上的能量聚集特性,通過在分?jǐn)?shù)階Fourier變換域?qū)Χ喾至緾hirp信號濾波的方法,完成了多分量Chirp信號的檢測和參數(shù)估計(jì)算法研究。 3.利用Chirp信號自身優(yōu)異的抗頻率選擇性衰落和抗多普勒頻移的特性,結(jié)合二進(jìn)制正交鍵控調(diào)制,在保障系統(tǒng)穩(wěn)定性的前提下設(shè)計(jì)了多載波Chirp擴(kuò)頻水聲通信系統(tǒng),接收端使用分?jǐn)?shù)階Fourier變換的方法進(jìn)行解調(diào),相比傳統(tǒng)的Chirp擴(kuò)頻系統(tǒng),速率得到了一定程度的提升。 4.針對多載波Chirp水聲通信系統(tǒng)的速率提升依賴于載波數(shù)量的問題,結(jié)合并行組合擴(kuò)頻技術(shù)提出了并行組合Chirp擴(kuò)頻水聲通信系統(tǒng),使得在發(fā)送較少載波的情況下實(shí)現(xiàn)系統(tǒng)速率的進(jìn)一步提升。接收端使用分?jǐn)?shù)階Fourier變換進(jìn)行解調(diào)提高了系統(tǒng)的可靠性,同時(shí)降低了接收機(jī)的復(fù)雜度。 5.針對實(shí)際水聲信道可能存在強(qiáng)碼間干擾的現(xiàn)象,將單陣元被動(dòng)時(shí)間反轉(zhuǎn)鏡技術(shù)應(yīng)用到并行組合Chirp擴(kuò)頻系統(tǒng)中。仿真結(jié)果表明,通過被動(dòng)時(shí)反技術(shù)的使用,并行組合Chirp擴(kuò)頻系統(tǒng)的高速和可靠的通信能力得以發(fā)揮得更好。 6.在實(shí)驗(yàn)室水池和廈門港附近海域?qū)嶒?yàn)表明,多載波Chirp擴(kuò)頻水聲通信系統(tǒng)和并行組合擴(kuò)頻Chirp水聲系統(tǒng)均可以較高的速率實(shí)現(xiàn)通信,同時(shí)也具有較高的可靠性。
[Abstract]:With the development and utilization of ocean, the reliability and speed of ocean acoustic communication are required. However, due to the complex characteristics of ocean channel, how to achieve high-speed and reliable underwater acoustic communication is a big challenge. Chirp signal is extended in both time and frequency domain, and it has good anti-frequency selective fading and anti-Doppler frequency shift characteristics in underwater communication process. Fractional Fourier transform, as a time-frequency transform with Chirp signal as its kernel function, has irreplaceable advantages in detecting and parameter estimation of Chirp signal. In this paper, the detection method of multi-component Chirp signal based on fractional Fourier transform is studied, and a multi-carrier Chirp spread spectrum system based on binary keying is designed. In order to solve the problem of increasing the speed of multi-carrier Chirp spread spectrum system in the limited underwater acoustic communication bandwidth, a parallel combined Chirp spread spectrum system is proposed by combining the parallel combined spread spectrum technology. The time reversal mirror of single array element is used as the anti-interference technology of communication system. The two systems were tested in the experimental pool of Xiamen University and the sea area near Xiamen Port. The results show that the two communication systems are capable of high-speed and reliable communication in a specific underwater environment. The main work of this paper is summarized as follows: 1. This paper introduces the research status of Chirp underwater acoustic communication at home and abroad, and the characteristics of ocean acoustic channel, analyzes the influence of channel on communication system; 2. Based on the energy aggregation of Chirp signals in fractional Fourier transform domain, the detection and parameter estimation algorithms of multi-component Chirp signals are studied by filtering multi-component Chirp signals in fractional Fourier transform domain. 3. Based on the excellent anti-frequency selective fading and anti-Doppler frequency shift characteristics of Chirp signal and binary quadrature keying modulation, a multi-carrier Chirp spread spectrum underwater acoustic communication system is designed under the premise of ensuring the stability of the system. The receiver uses fractional Fourier transform to demodulate, and the rate is improved compared with the traditional Chirp spread spectrum system. 4. In order to solve the problem that the rate increase of multi-carrier Chirp underwater acoustic communication system depends on the number of carriers, a parallel combined Chirp spread spectrum underwater acoustic communication system is proposed by combining the parallel combined spread spectrum technology. The system speed can be further improved under the condition of sending fewer carriers. The receiver uses fractional Fourier transform to demodulate the system, which improves the reliability of the system and reduces the complexity of the receiver. 5. Aiming at the phenomenon of strong inter-symbol interference (ISI) in underwater acoustic channel, the passive time reversal mirror technique of single array element is applied to the parallel combined Chirp spread spectrum system. The simulation results show that the high speed and reliable communication ability of the parallel combined Chirp spread spectrum system can be improved by the use of passive time inverse technique. 6. The experiments in the laboratory pool and near Xiamen Port show that both the multi-carrier Chirp spread spectrum underwater acoustic communication system and the parallel combined spread spectrum Chirp underwater acoustic system can realize the communication at a higher rate and have a higher reliability at the same time.
【學(xué)位授予單位】：廈門大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TN929.3

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