深空Ka頻段鏈路的自適應傳輸及編碼策略研究
發(fā)布時間：2018-08-06 14:56
【摘要】：具有高傳輸速率和大信道帶寬的Ka(28~35 GHz)頻段越來越多地應用在深空通信業(yè)務中。然而,深空Ka頻段鏈路質(zhì)量受太陽上合段太陽閃爍和近地段降雨的影響,鏈路的誤碼率(Bit Error Rate,BER)波動較大,限制了鏈路的高速率傳輸�；诖�,本課題引入Markov理論對深空Ka頻段鏈路的動態(tài)特性進行研究建模,并考慮發(fā)送端無法獲得實時信道狀態(tài)信息(Channel State Information,CSI)的限制條件,用時間序列分析法中的自回歸移動平均算法(Autoregressive-moving-average,ARMA)對信道狀態(tài)進行預測。由于預測誤差的客觀存在,使用能夠抗信道估計偏差的模擬噴泉編碼(Analog fountain codes,AFC)作為前向糾刪技術,結(jié)合預測算法對深空Ka頻段鏈路質(zhì)量進行聯(lián)合優(yōu)化,確定了適應于深空Ka頻段的自適應編碼傳輸方案。具體的研究內(nèi)容如下:研究深空通信太陽閃爍信道和Ka頻段降雨衰落信道的動態(tài)傳輸,兩者都符合Markov轉(zhuǎn)移特性。用Markov鏈建模深空通信太陽閃爍信道和降雨衰落信道,并仿真對比模擬衰減時序數(shù)據(jù)與實測衰減時序數(shù)據(jù)的誤差,驗證了模型的可行性。利用建好的Markov鏈產(chǎn)生模擬太陽閃爍數(shù)據(jù)和模擬雨衰數(shù)據(jù),作為后續(xù)深空通信Ka頻段鏈路衰減的實時預測研究基礎�？紤]深空通信長時延情況無法獲得實時CSI,課題采用預測效果好并且算法步驟簡單的ARMA對Ka頻段鏈路的太陽閃爍和降雨衰減進行實時動態(tài)預測。利用“太陽閃爍Markov鏈”和“降雨衰減Markov鏈”產(chǎn)生數(shù)據(jù)對ARMA算法進行模型識別和參數(shù)選擇。仿真驗證了該預測算法可以取得很好的預測精度,同時分析了前導數(shù)據(jù)個數(shù)和預測步長對預測精度的影響。雖然ARMA實時預測算法具有很好的預測精度,但預測誤差是始終存在的。為了抵抗信道狀態(tài)信息估計偏差對傳輸性能的影響,本課題采用在較大信噪比(Signal-to-Noise Ratio,SNR)范圍內(nèi)具有良好譯碼性能的AFC作為前向糾刪分組技術。并將其與鏈路預測算法相結(jié)合,對深空通信Ka鏈路的誤碼率波動進行優(yōu)化,確定了深空Ka頻段自適應傳輸編碼方案。理論分析了自適應編碼傳輸方案的吞吐率,仿真分析了該方案的吞吐率,并將其與固定速率編碼傳輸方案以及自適應LT碼傳輸方案的吞吐率進行對比,本課題提出方案的吞吐率達到最高,從而驗證了該方案可以保持深空Ka頻段的數(shù)據(jù)連續(xù)性以及鏈路的高吞吐率。
[Abstract]:The Ka (28N 35 GHz) band with high transmission rate and large channel bandwidth is increasingly used in deep space communication services. However, the link quality in the deep space Ka band is affected by solar flicker in the upper solar segment and rainfall in the near area. The BER (bit error rate) of the link fluctuates greatly, which limits the high rate transmission of the link. Based on this, this paper introduces Markov theory to model the dynamic characteristics of deep space Ka-band links, and considers the limitation condition that the sender can not obtain real-time channel state information (Channel State). The autoregressive moving average (ARMA) algorithm in time series analysis is used to predict the channel state. Because of the objective existence of prediction error, the analog fountain code (Analog fountain codes-AFC, which can resist channel estimation deviation, is used as the forward erasure technique, and the link quality in deep space Ka band is jointly optimized by combining the prediction algorithm. The adaptive coding transmission scheme for deep space Ka band is determined. The main contents are as follows: the dynamic transmission of solar scintillation channel and Ka-band rainfall fading channel in deep space communication is studied. Both of them accord with the Markov transfer characteristics. The solar scintillation channel and rainfall fading channel in deep space communication are modeled by Markov chain, and the error between simulated attenuation time series data and measured attenuation time series data is compared to verify the feasibility of the model. Simulated solar scintillation data and simulated rain attenuation data are generated by using the constructed Markov chain, which is the basis of real-time prediction of Ka-band link attenuation in subsequent deep space communications. Considering that long time delay can not be obtained in deep space communication, ARMA, which has good prediction effect and simple algorithm steps, is used to dynamically predict solar flicker and rainfall attenuation in Ka band link. The model identification and parameter selection of the ARMA algorithm are carried out by using the data generated by "solar scintillation Markov chain" and "rainfall attenuated Markov chain". The simulation results show that the prediction algorithm can achieve good prediction accuracy. At the same time, the influence of the number of leading data and the prediction step size on the prediction accuracy is analyzed. Although the ARMA real-time prediction algorithm has a good prediction accuracy, but the prediction error is always there. In order to resist the influence of channel state information estimation error on transmission performance, the AFC with good decoding performance in the range of large signal-to-noise ratio (Signal-to-Noise) is adopted as the forward erasure correction block technique. Combining with the link prediction algorithm, the error rate fluctuation of Ka link in deep space communication is optimized, and the adaptive transmission coding scheme in deep space Ka band is determined. The throughput of the adaptive coding transmission scheme is analyzed theoretically, and the throughput of the scheme is simulated and analyzed, and the throughput of the scheme is compared with that of the fixed rate coding transmission scheme and the adaptive LT transmission scheme. In this paper, the throughput of the proposed scheme is the highest, which verifies that the scheme can maintain the data continuity in the deep space Ka band and the high throughput of the link.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TN927
本文編號：2168080
[Abstract]:The Ka (28N 35 GHz) band with high transmission rate and large channel bandwidth is increasingly used in deep space communication services. However, the link quality in the deep space Ka band is affected by solar flicker in the upper solar segment and rainfall in the near area. The BER (bit error rate) of the link fluctuates greatly, which limits the high rate transmission of the link. Based on this, this paper introduces Markov theory to model the dynamic characteristics of deep space Ka-band links, and considers the limitation condition that the sender can not obtain real-time channel state information (Channel State). The autoregressive moving average (ARMA) algorithm in time series analysis is used to predict the channel state. Because of the objective existence of prediction error, the analog fountain code (Analog fountain codes-AFC, which can resist channel estimation deviation, is used as the forward erasure technique, and the link quality in deep space Ka band is jointly optimized by combining the prediction algorithm. The adaptive coding transmission scheme for deep space Ka band is determined. The main contents are as follows: the dynamic transmission of solar scintillation channel and Ka-band rainfall fading channel in deep space communication is studied. Both of them accord with the Markov transfer characteristics. The solar scintillation channel and rainfall fading channel in deep space communication are modeled by Markov chain, and the error between simulated attenuation time series data and measured attenuation time series data is compared to verify the feasibility of the model. Simulated solar scintillation data and simulated rain attenuation data are generated by using the constructed Markov chain, which is the basis of real-time prediction of Ka-band link attenuation in subsequent deep space communications. Considering that long time delay can not be obtained in deep space communication, ARMA, which has good prediction effect and simple algorithm steps, is used to dynamically predict solar flicker and rainfall attenuation in Ka band link. The model identification and parameter selection of the ARMA algorithm are carried out by using the data generated by "solar scintillation Markov chain" and "rainfall attenuated Markov chain". The simulation results show that the prediction algorithm can achieve good prediction accuracy. At the same time, the influence of the number of leading data and the prediction step size on the prediction accuracy is analyzed. Although the ARMA real-time prediction algorithm has a good prediction accuracy, but the prediction error is always there. In order to resist the influence of channel state information estimation error on transmission performance, the AFC with good decoding performance in the range of large signal-to-noise ratio (Signal-to-Noise) is adopted as the forward erasure correction block technique. Combining with the link prediction algorithm, the error rate fluctuation of Ka link in deep space communication is optimized, and the adaptive transmission coding scheme in deep space Ka band is determined. The throughput of the adaptive coding transmission scheme is analyzed theoretically, and the throughput of the scheme is simulated and analyzed, and the throughput of the scheme is compared with that of the fixed rate coding transmission scheme and the adaptive LT transmission scheme. In this paper, the throughput of the proposed scheme is the highest, which verifies that the scheme can maintain the data continuity in the deep space Ka band and the high throughput of the link.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TN927
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