本文關(guān)鍵詞： 同時同頻全雙工 自干擾抑制 自干擾信道估計 模數(shù)轉(zhuǎn)換 動態(tài)范圍　出處：《哈爾濱工業(yè)大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：隨著近年來通信技術(shù)的不斷發(fā)展,無線通信系統(tǒng)對頻譜利用率以及通信效率等指標(biāo)的要求越來越高,同時同頻全雙工通信系統(tǒng)在原有半雙工通信方式的基礎(chǔ)上可以在理論上提高一倍的傳輸效率。然而,來自本地發(fā)射機(jī)的強(qiáng)自干擾信號是全雙工通信系統(tǒng)的最大障礙,關(guān)于自干擾抑制的研究是系統(tǒng)的研究重點(diǎn)之一。因此,本文將重點(diǎn)針對模擬域與數(shù)字域的自干擾抑制算法與模塊的設(shè)計進(jìn)行研究,并在此基礎(chǔ)上進(jìn)行系統(tǒng)有效性的驗證。首先,對全雙工通信基礎(chǔ)以及系統(tǒng)模型進(jìn)行研究分析。介紹了同時同頻全雙工通信系統(tǒng)及其收發(fā)機(jī)模型,研究了OFDM信號模型以及通信信道和自干擾信道模型。在同時同頻全雙工通信系統(tǒng)背景下,通信信道模型為瑞利衰落模型,自干擾信道模型為K萊斯因子較大的萊斯信道。第二,對模擬域自干擾抑制進(jìn)行研究。采用信道估計重建模擬自干擾的方式對消抑制模擬自干擾,利用OFDM系統(tǒng)中的IFFT模塊在頻域利用乘積代替卷積的方式降低重建自干擾的復(fù)雜度,實驗驗證了在全雙工高干噪比背景下,LS算法與MMSE算法進(jìn)行信道估計的性能相近,在模擬自干擾抑制模塊可以抑制32d B的自干擾。第三,對大動態(tài)范圍模數(shù)轉(zhuǎn)換算法的研究。分析了在信干噪比極低的背景下,提高模數(shù)轉(zhuǎn)換動態(tài)范圍研究的必要性,提出了一種基于模數(shù)轉(zhuǎn)換量化誤差信號補(bǔ)償?shù)募壜?lián)形式大動態(tài)范圍模數(shù)轉(zhuǎn)換算法,驗證了算法的有效性,并結(jié)合全雙工通信系統(tǒng)實驗背景分析了算法中所需采用的AD、DA轉(zhuǎn)換器所滿足的有效動態(tài)范圍應(yīng)不低于50d B和75d B,仿真驗證了算法可在8位AD的基礎(chǔ)上提高20d B左右的動態(tài)范圍。最后,對數(shù)字域自干擾抑制進(jìn)行研究。改進(jìn)原有工作方式,在自干擾信道隨時間變化不十分明顯的前提下,采用在全雙工工作之前以半雙工的訓(xùn)練模式進(jìn)行信道估計作為重建數(shù)字自干擾信號的依據(jù)并結(jié)合復(fù)雜度低的頻域最小二乘算法進(jìn)行信道估計,實驗驗證該估計方法可以比基于梳狀導(dǎo)頻的信道估計提高15d B的自干擾抑制量。在不同信干噪比的條件下結(jié)合模擬自干擾抑制研究了整個系統(tǒng)的自干擾抑制量,實驗驗證數(shù)字自干擾抑制模塊可抑制36d B的自干擾,系統(tǒng)整體可抑制68d B自干擾。在不同信干噪比條件下比較系統(tǒng)的解調(diào)誤碼率與相同指標(biāo)下半雙工系統(tǒng)的誤碼率,驗證了在不低于-55d B信干噪比條件下自干擾可以得到有效抑制的結(jié)論。綜上所述,本文在同時同頻全雙工OFDM通信系統(tǒng)的背景下,對主動自干擾抑制進(jìn)行了研究,提出了全雙工通信背景下的大動態(tài)范圍模數(shù)轉(zhuǎn)換算法并驗證其有效性。最終以自干擾抑制量為指標(biāo)驗證了自干擾抑制的有效性并以誤碼率為指標(biāo)驗證了通信系統(tǒng)的有效性。
[Abstract]:With the development of communication technology in recent years, the requirements of wireless communication system for spectrum efficiency and communication efficiency are becoming higher and higher. On the basis of the original half-duplex communication mode, the transmission efficiency can be doubled theoretically in the same frequency full-duplex communication system. However, the strong self-interference signal from the local transmitter is the biggest obstacle to the full-duplex communication system. The research of self-interference suppression is one of the key points of the system. Therefore, this paper will focus on the design of algorithms and modules for self-interference suppression in analog and digital domains, and then verify the effectiveness of the system. The basis and system model of full duplex communication are studied and analyzed, and the simultaneous frequency full duplex communication system and its transceiver model are introduced. The OFDM signal model, the communication channel and the self-interference channel model are studied. In the background of the simultaneous co-frequency full-duplex communication system, the communication channel model is Rayleigh fading model, and the self-interference channel model is the Rice channel with higher K rice factor. In this paper, self-interference suppression in analog domain is studied. Using channel estimation to reconstruct analog self-interference to suppress simulated self-interference, IFFT module in OFDM system is used to reduce the complexity of reconstruction self-interference by using product instead of convolution in frequency domain. The experimental results show that the channel estimation performance of the LS algorithm is similar to that of the MMSE algorithm under the background of full duplex and high error-noise ratio. In the analog self-interference suppression module, the self-interference of 32dB can be suppressed. Thirdly, This paper analyzes the necessity of improving the dynamic range of A / D conversion under the background of low signal-to-noise ratio. In this paper, a large dynamic range A / D conversion algorithm based on analog to digital conversion quantization error signal compensation is proposed, and the validity of the algorithm is verified. Combined with the experimental background of full-duplex communication system, the effective dynamic range of ADDA converter used in the algorithm should be no less than 50dB and 75dB, and the simulation results show that the algorithm can improve 20dB on the basis of 8-bit AD. Dynamic range. Finally, The self-interference suppression in digital domain is studied. The original mode of operation is improved, and the self-interference channel does not change obviously with time. Channel estimation based on half-duplex training mode before full-duplex operation is used as the basis for reconstruction of digital self-interference signal and channel estimation is carried out by using low-complexity frequency-domain least square algorithm. Experimental results show that the proposed method can increase the self-interference suppression by 15dB compared with the channel estimation based on comb pilot. The self-interference suppression of the whole system is studied in combination with simulated self-interference suppression under different signal-to-noise ratios. The experimental results show that the digital self-interference suppression module can suppress the self-interference of 36dB and the whole system can suppress the 68dB self-interference. The demodulation error rate of the system is compared with that of the half-duplex system under the same index under different signal-to-noise ratio. The conclusion that self-interference can be effectively suppressed under the condition of not less than -55dB signal-to-noise ratio is verified. In summary, active self-interference suppression is studied under the background of simultaneous full-duplex OFDM communication system. In this paper, a large dynamic range A / D conversion algorithm in full duplex communication is proposed and its validity is verified. Finally, the effectiveness of self interference suppression is verified by using self interference suppression as an indicator, and the effectiveness of the communication system is verified by using the bit error rate (BER) as the index.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：TN929.53
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本文編號：1519546