本文選題：短波通信標準 + 高階QAM信號　； 參考：《解放軍信息工程大學(xué)》2014年碩士論文

【摘要】：正交幅度調(diào)制(Quadrature Amplitude Modulation,QAM)由于具有高頻譜利用率,在高速短波通信中的應(yīng)用日漸廣泛。2011年公布的MIL-STD-188-110C協(xié)議首次將高階QAM引入美軍短波通信標準中,對非合作接收端的解調(diào)技術(shù)提出了更高的要求。本文研究了MIL-STD-188-110C協(xié)議高階QAM信號的盲解調(diào)關(guān)鍵技術(shù),包括盲均衡、盲定時同步以及盲載波同步技術(shù)。論文工作為作者所在實驗室承擔的某大型工程項目的一部分。論文的主要工作和創(chuàng)新點可概括如下:1、分析了110C協(xié)議信號和短波信道的特點,結(jié)合實際條件和任務(wù)規(guī)劃明確了本文課題背景下協(xié)議高階QAM信號解調(diào)的關(guān)鍵技術(shù)步驟。2、在盲均衡方面,首先針對協(xié)議信號星座的特點,給出了一種適用于圓形星座高階QAM信號的基于區(qū)域判決的符號間隔混合多模盲均衡算法,通過改進區(qū)域劃分方式,構(gòu)造新的誤差函數(shù)及引入數(shù)據(jù)重用技術(shù),降低了穩(wěn)態(tài)誤差,減少了收斂所需符號個數(shù)。然后針對符號間隔均衡器在多徑深衰落信道下性能惡化的問題,將分數(shù)間隔預(yù)測判決反饋均衡結(jié)構(gòu)與誤差判決雙模式多模算法相結(jié)合,給出了一種收斂性能穩(wěn)健的盲均衡算法,有效實現(xiàn)多徑深衰落信道下的協(xié)議高階QAM信號盲均衡。3、在協(xié)議高階QAM信號盲定時同步方面,針對基于最大似然的定時誤差估計算法在短波信道下性能不佳的問題,研究了基于循環(huán)統(tǒng)計量的定時誤差估計算法,在此基礎(chǔ)上結(jié)合實際情況與載波同步相結(jié)合,給出了適用于頻率選擇性衰落信道的基于高階循環(huán)累積量的定時與載波同步參數(shù)聯(lián)合估計算法,實現(xiàn)了信號的定時誤差、載波頻偏及相偏的聯(lián)合盲估計。仿真實驗表明,在低信噪比和惡劣短波信道下,所提算法對協(xié)議高階QAM信號相較于二階循環(huán)統(tǒng)計量定時誤差估計算法具有更低的均方誤差,相較于遍歷搜索循環(huán)頻率估計頻偏的算法提高了頻偏估計精度,且對相位誤差具有良好的估計性能。4、在協(xié)議高階QAM信號盲載波同步方面,針對實際短波通信環(huán)境,將時變頻偏列入考慮范圍,給出了一種基于二次相位函數(shù)的載波同步參數(shù)聯(lián)合估計算法,將多普勒頻率變化率、頻偏和相偏進行聯(lián)合估計,較傳統(tǒng)頻偏估計算法更適用于時變頻偏環(huán)境;在反饋結(jié)構(gòu)算法方面,給出了多狀態(tài)自適應(yīng)擴展卡爾曼濾波載波同步算法,通過分析濾波器環(huán)路帶寬的動態(tài)特性,細化濾波器的工作狀態(tài),相較于現(xiàn)有同類算法提高了頻偏捕獲速度,擴大了捕獲范圍,增強了對時變頻偏的跟蹤能力。最后將所提卡爾曼同步算法與盲均衡算法相結(jié)合,實現(xiàn)了多徑衰落信道下盲均衡與載波同步的聯(lián)合結(jié)構(gòu),增強了算法的實用性。
[Abstract]:Quadrature Amplitude Modulation QAM (Quadrature Amplitude Modulation) has been widely used in high speed HF communication due to its high spectral efficiency. MIL-STD-188-110C protocol published in 2011 first introduced high-order QAM into the U.S.Army shortwave communication standard. A higher demand is put forward for the demodulation technology of the non-cooperative receiver. In this paper, the key techniques of high order QAM signal demodulation based on MIL-STD-188-110C protocol are studied, including blind equalization, blind timing synchronization and blind carrier synchronization. The work of the thesis is part of a large project undertaken by the author in the laboratory. The main work and innovation of this paper can be summarized as follows: 1. The characteristics of 110C protocol signal and shortwave channel are analyzed. Combined with practical conditions and task planning, the key technical steps of high order QAM signal demodulation under the background of this thesis are defined. In blind equalization, firstly, the characteristics of protocol signal constellation are pointed out. This paper presents a region decision based mixed multimode blind equalization algorithm for high order QAM signals of circular constellations. By improving the region division, constructing a new error function and introducing data reuse techniques, the steady-state error is reduced. The number of symbols required for convergence is reduced. Then, aiming at the problem of the performance deterioration of symbol interval equalizer in multipath deep fading channel, a robust blind equalization algorithm with convergence performance is proposed by combining the fractional interval predictive decision feedback equalization structure with the error decision double mode multimode equalization algorithm. Blind equalization of high order QAM signals in multipath deep fading channels is realized effectively. In the aspect of blind timing synchronization of high order QAM signals, the performance of timing error estimation algorithm based on maximum likelihood is poor in short wave channels. In this paper, the timing error estimation algorithm based on cyclic statistics is studied. Based on this algorithm, the carrier synchronization is combined with the actual situation. A joint estimation algorithm of timing and carrier synchronization parameters based on high order cyclic cumulants is proposed for frequency selective fading channels. The joint blind estimation of timing error carrier frequency offset and phase offset is realized. Simulation results show that the proposed algorithm has lower mean square error than the second order cyclic statistic timing error estimation algorithm for high order QAM signals in low SNR and bad HF channels. Compared with the ergodic search algorithm for frequency offset estimation, the frequency offset estimation accuracy is improved, and the phase error is estimated. 4. In the aspect of blind carrier synchronization of high order QAM signals, we aim at the actual shortwave communication environment. A joint estimation algorithm of carrier synchronization parameters based on quadratic phase function is presented, in which Doppler frequency change rate, frequency offset and phase offset are jointly estimated. Compared with the traditional frequency offset estimation algorithm, it is more suitable for time-conversion bias environment. In the aspect of feedback structure algorithm, a multi-state adaptive extended Kalman filter carrier synchronization algorithm is presented, and the dynamic characteristics of the filter loop bandwidth are analyzed. Compared with the existing algorithms, the filter can improve the frequency offset acquisition speed, enlarge the acquisition range, and enhance the tracking ability of time-conversion offset. Finally, the proposed Kalman synchronization algorithm is combined with the blind equalization algorithm to realize the joint structure of blind equalization and carrier synchronization in multipath fading channels, which enhances the practicability of the algorithm.
【學(xué)位授予單位】：解放軍信息工程大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TN911.3

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