二维扩频系统的抗干扰部分性能研究

【作者】 谢胜琳；

【导师】 唐友喜；

【作者基本信息】 电子科技大学 ， 通信与信息系统， 2006， 硕士

【摘要】 扩展频谱技术优越的抗干扰能力是扩频通信得到迅速发展的重要原因，其出现是通信技术的一次重大突破。而近年来出现的分别在时域、频域上对原始信号进行频谱扩展的二维扩频(2DSS)通信，是对传统的一维时域直接序列扩频(DSSS)和多载波码分多址(MC-CDMA)扩频的推广。 本论文侧重研究了二维扩频系统的抗干扰部分性能，重点对二维扩频通信在加性高斯白噪声(AWGN)信道以及瑞利(Rayleigh)衰落信道下抗单音干扰性能的原理和算法进行了深入研究。并且以AWGN信道为例，分析、比较了二维扩频与一维DS扩频和MC扩频的抗单音干扰性能。 本文首先介绍了扩频通信系统的特点以及发展，给出了本文的研究方向。为了更直观分析二维扩频系统的抗干扰性能，在第二章详细介绍了二维扩频技术的研究现状。 宽带和窄带干扰对扩频通信系统性能的影响越来越引起人们的重视，本文系统全面地阐述了二维扩频系统抗部分频带干扰的性能，并且基于Matlab和Cossap仿真平台，给出了二维扩频系统抗单脉冲干扰的仿真结果。 然后重点分析了常见的单音干扰对扩频通信系统性能的影响，详细阐述了二维扩频系统抗单音干扰性能算法的基本原理，分别在AWGN信道和瑞利衰落信道下给出了系统抗单音干扰的误比特率(BER)理论推导结果，并且给出了仿真验证；揭示出当单音干扰的频点在某个子载波的中心频点上且二维扩频矩阵满足一定条件时，干扰对系统性能基本无影响。 最后本文以AWGN信道为例，针对BPSK调制的一维和二维扩频系统，分析比较了DS-CDMA系统和MC-CDMA系统与二维扩频系统的抗单音干扰性能异同。给出了三个系统在单音干扰环境中的BER理论分析结果和仿真；结果表明在相同的数据速率和带宽下，二维扩频系统的抗单音干扰性能介于直接序列扩频和多载波扩频系统之间。 一维的CDMA扩频技术，可以看作是二维扩频系统的频域扩频序列为“1”的一种特例，因此，可以用二维扩频的接收技术接收一维的CDMA信号。由于二更多还原

【Abstract】 The spread spectrum communication has been developed very quickly because of its superior performance of anti-jamming while its appearance brought a significant break to the communication technologies. The original signal is spreaded in time and frequency domain simultaneously in the two Dimensional Spread Spectrum (2DSS) technology, which is the extension of traditional Direct Sequence Spread Spectrum (DSSS) and Multi-Carrier Code Division Multiple Access (MC-CDMA).In this thesis, the performance of anti-jamming in the 2DSS system will be mainly studied in a certain extent. After that, the principles and the algorithm of 2DSS over AWGN and Rayleigh channels with single-tone jamming will also be studied. Then the Bit Error Ratio(BER) performance of the single-tone jamming between the one dimension DSS system, MC-CDMA system and the 2DSS system under the AWGN channel will be discussed.First we introduce the characteristics and the development of the spread spectrum systems and the direction of study will be shown. The research state of 2DSS will be summarized in the second part in order to analyze the anti-jamming performance of the system more clearly.More and more people focus on the impact of wide-band and narrow-band interference to the spread spectrum communication. In this paper we will analyze the anti-jamming performance of the partial-band interference in 2DSS system comprehensively, and give the simulation results on anti-single-pulse jamming based on the platform of Matlab and Cossap.Then the impact of the normal single-tone jamming to 2DSS communication and the basic principle of anti-single-tone-jamming will be mainly analyzed. The BER of the anti-single-tone jamming over AWGN channel and multi-path Rayleigh channels in 2D-CDMA system will be derived, the simulation results of the BER will be provided as well. Then we conclude that the effect of the jamming can be almost eliminated, when the frequency of the jamming is exactly equal to the frequency of any sub-carrier, and a certain requirement of the 2D spreading-matrix is satisfied.At last, the performance of BPSK modulation between one and two dimensional spread spectrum system with single-tone jamming over AWGN channel will be compared and analyzed. The BER of the three systems will be analyzed, and the simulation results of the BER will be shown, then we conclude that the performance of the anti-jamming in 2D-CDMA system is between the DS-CDMA system and the MC-CDMA system under the same data bit rate and the same bandwidth.The technology of one dimensional CDMA can be considered as the special example of 2D-CDMA when the sequence of frequency domain set to all ‘1’s. Thus the one dimension CDMA signals can be received by the technology of two dimensional receiver. The performance of the anti-jamming in one-dimensional DS system can be更多还原