發(fā)布時間：2019-06-29 12:37

【摘要】：隨著無線通信的發(fā)展,通信系統(tǒng)的抗干擾性能日益成為人們關(guān)注的重點,因此擴頻技術(shù)應(yīng)需而生并被廣泛應(yīng)用。在擴頻通信系統(tǒng)中信號同步問題是影響系統(tǒng)性能的關(guān)鍵因素。在無線局域網(wǎng)中的突發(fā)通信模式使得在擴頻組網(wǎng)突發(fā)通信中的同步問題更加成為人們研究的焦點。所以,本文對此類同步問題進行了相關(guān)的研究。首先,本文簡要介紹了兩種擴頻技術(shù)的發(fā)展背景,以及突發(fā)通信的特點。在敘述了兩種擴頻系統(tǒng)的基本原理,并對直接序列擴頻系統(tǒng)中的擴頻偽碼同步方法進行了系統(tǒng)的闡述之后,重點分析了跳頻圖案同步中的等待式同步法在軍事通信中易于被敵人精確干擾的缺點,針對該缺點本文在組網(wǎng)通信的條件下,提出了一種新的同步方案,即離散頻點同步法。與傳統(tǒng)等待式同步方案在單一頻率等待不同,新方案利用網(wǎng)絡(luò)知識分別估計跳頻圖案中每一個頻率的起始時刻,從而離散地解跳。如果某一個頻率沒有捕獲到,接收機可以根據(jù)預(yù)期信息繼續(xù)捕獲下一個頻率,因此,新方案中的整體同步過程并不會受影響。為仿真上述同步方法,本文在MATLAB/Simulink平臺下搭建了三個系統(tǒng)模型,即基帶直接序列擴頻系統(tǒng)、基于直接序列擴頻的預(yù)期幀檢測系統(tǒng)和跳頻通信系統(tǒng)。在上述系統(tǒng)中,擴頻偽碼的同步采用基于長序列相關(guān)的方法,跳頻圖案的同步則采用本文提出的離散頻點同步方案�；谥苯有蛄袛U頻的兩個系統(tǒng)分別用于研究上述擴頻偽碼同步方法的抗噪聲性能,以及該同步方法在具有一定網(wǎng)絡(luò)知識的條件下的抗干擾性能。跳頻通信系統(tǒng)用于研究新提出的離散頻點同步方案的抗噪聲性能、抗單頻點干擾和抗特定頻帶干擾性能。最后,通過仿真本文得出如下結(jié)論:直接序列擴頻的擴頻偽碼同步方法隨著信噪比增加,同步的準(zhǔn)確率提高,并在接近0dB處,準(zhǔn)確率達到90%;預(yù)期幀檢測系統(tǒng)隨著信干比增加,檢測的準(zhǔn)確概率即同步準(zhǔn)確概率也在提升,不同的預(yù)期幀格式,對應(yīng)的同步性能不同;跳頻系統(tǒng)的抗高斯噪聲性能與一般非擴頻通信系統(tǒng)相同,而采取離散頻點同步方案的跳頻系統(tǒng)比采取等待式同步方案的跳頻系統(tǒng)的抗單頻點干擾能力強,而對于特定頻帶干擾,信干比增加,系統(tǒng)誤碼率降低。不同的干擾因子對應(yīng)著跳頻系統(tǒng)不同的誤比特率性能曲線,但對于采用新同步方案的跳頻系統(tǒng),在接近13dB處,誤比特率都小于1e-3。
[Abstract]:With the development of wireless communication, the anti-interference performance of communication system has increasingly become the focus of attention, so spread spectrum technology should be born and widely used. Signal synchronization is the key factor affecting the performance of spread spectrum communication system. The burst communication mode in wireless local area network (WLAN) makes the synchronization problem in spread spectrum network burst communication more the focus of people's research. Therefore, this paper has carried on the related research to this kind of synchronization problem. First of all, this paper briefly introduces the development background of the two spread spectrum technologies and the characteristics of burst communication. After describing the basic principles of two kinds of spread spectrum systems and systematically expounding the synchronization method of spread spectrum pseudo codes in direct sequence spread spectrum systems, this paper focuses on the analysis of the shortcomings of waiting synchronization method in frequency hopping pattern synchronization, which is easy to be accurately interfered by the enemy in military communications. in view of this disadvantage, a new synchronization scheme, discrete frequency point synchronization method, is proposed in this paper under the condition of network communication. Different from the traditional waiting synchronization scheme at a single frequency, the new scheme uses network knowledge to estimate the starting time of each frequency in the frequency hopping pattern, so that the jump can be solved discretively. If a certain frequency is not captured, the receiver can continue to capture the next frequency according to the expected information, so the overall synchronization process in the new scheme will not be affected. In order to simulate the above synchronization method, three system models are built on MATLAB/Simulink platform, namely, baseband direct sequence spread spectrum system, expected frame detection system based on direct sequence spread spectrum and frequency hopping communication system. In the above system, the synchronization of spread spectrum pseudo-codes is based on long sequence correlation, and the synchronization of frequency hopping patterns is based on the discrete frequency point synchronization scheme proposed in this paper. Two systems based on direct sequence spread spectrum are used to study the anti-noise performance of the above spread spectrum pseudo-code synchronization method and the anti-interference performance of the synchronization method under certain network knowledge. The frequency hopping communication system is used to study the anti-noise performance, anti-single frequency point interference and anti-specific frequency band interference performance of the new discrete frequency point synchronization scheme. Finally, through simulation, the following conclusions are drawn: with the increase of signal-to-noise ratio (SNR), the accuracy of synchronization of spread spectrum pseudo-code synchronization method of direct sequence spread spectrum is improved, and the accuracy of synchronization is 90% when it is close to 0dB. With the increase of signal-to-interference ratio, the accurate probability of detection, that is, synchronization accuracy probability, is also improved, and the corresponding synchronization performance is different with different expected frame formats. The anti-Gaussian noise performance of frequency hopping system is the same as that of general non-spread spectrum communication system, but the frequency hopping system with discrete frequency point synchronization scheme has stronger anti-single frequency point interference ability than the frequency hopping system with waiting synchronization scheme, while for specific frequency band interference, the signal-to-interference ratio increases and the bit error rate of the system decreases. Different interference factors correspond to different bit error rate performance curves of frequency hopping system, but for frequency hopping system with new synchronization scheme, the bit error rate is less than 1e 鈮，

本文編號：2507825