摘要
超宽带无线通信技术(UWB, Ultra Wide Band)的研发为人们解决无线通信频谱资源匮乏的问题提供了新的方案和思路。这种通信技术因其极宽的频谱范围,可以达到很高的信息传输速率,同时又兼具抗干扰性能强、发送功率小的优势。随着认知无线电技术的发展,UWB有了新的发展方向,认知超宽带(CUWB, Cognitive UWB)。CUWB较之传统的UWB有了长足进步。它的优势在于:可以对任意形状的辐射掩蔽进行匹配并且能够对任意频点窄带干扰进行避免。相应的,对所使用脉冲的性能也提出了更高的要求。
本文的重点是基于PSWF(Prolate Spheroidal Wave Function)的超宽带脉冲产生算法的研究和改进。首先通过对PSWF脉冲产生算法的仿真,得出了“基于PSWF的脉冲产生算法最适合于CUWB技术”的结论。然后,为了使PSWF脉冲能够避免窄带信号的干扰,在PSWF脉冲产生算法的思路之上,分别改进出不同步长搜索法及使用滤波器的多频带脉冲组合法两种脉冲产生算法。通过在不同窄带干扰情况下的仿真发现,不同步长搜索法解决了以往算法中不能准确控制陷波点和陷波效果不稳定的问题,不但实现了任意频点的陷波功能,而且产生脉冲在任意陷波频点的功率谱密度维持在-75dBm左右;使用滤波器的多频带脉冲组合法陷波效果虽不及不同步长搜索法,但在保证陷波频点准确控制的同时,频谱利用率高于不同步长搜索法。
The technology of UWB (Ultra Wide Band) provides a new scheme for people to solve the problem about scarcity of frequency resource. This technology can make a large throughput for its wide band, also, it has powerful noise-resistance and low radiated power. Along with the exploitation of Cognitive Radio, UWB has a new development, CUWB (Cognitive UWB). Comparing the traditional UWB, CUWB makes a considering improvement: it can match a variable emission mask and suppress a narrow band interference in any frequency. Correspondingly, it puts forward higher requirement for performance of UWB impulse.
The article emphasized on research and improvement of algorithm of impulse generation based PSWF(Prolate Spheroidal Wave Function). At first, we educed a conclusion that the impulse based PSWF fits CUWB best through simulations, and then, in order to suppress a narrow band interference , we make out two algorithm of impulse generation,“Different steps searching”and“Multi-band impulses composing”.
After many simulations in different situations, it seems that“Different steps searching”can solve the problem that the notch of spectrum can’t be controlled precisely and the result of spectrum suppressing isn’t stable in formal algorithm. Not only the notch of spectrum can be controlled precisely, but also the PSD in such notch is as low as -75dBm. Even though the result of spectrum suppressing by“Multi-band impulses composing”is not as good as“Different steps searching”,“Multi-band impulses composing”can acquire a higher utilization per cent in spectrum.
引文
[1] Barrett T W. ,“History of Ultra Wide Band(UWB) Radar & Communication: Pioneer and Innovators”, In: Progress In Electromagnetic Symposium 2000, PIERS2000, 2000.
[2] FCC 02-48, FIRST REPORT AND ORDER. Adopted: 2002, February 14, Released: 2002.
[3] Faranak Nekoogar,“Ultra-Wideband Communications: Fundamentals and Applications”, Chapter1, pages(s): 9-12.
[4]陈国东,武穆清,“超宽带和认知无线电的完美结合”,通信世界,07年第二期,feb,2007,Page:6.
[5]葛利嘉,曾凡鑫,刘郁林,岳光荣,“超宽带无线通信”,北京:国防工业出版社,2005,8.
[6] Foerster J, Li Q. UWB channel modeling contribution from intel.IEEE document #02279r0p802-15-SG3a.
[7] Moe Z W , Cassioli D. The ultra-wide bandwidth indoor channel: from statistical model to simulations. IEEE document #02284r0p802-15-SG3a.
[8] Ghassemzadeh S S,Greenstein L J, Tarokhm V. The ultra-wideband indoor multipath model to simulations. IEEE document #02282r0p802-15-SG3a.
[9] Pendergrass M, Beeler W C. Empirically based statistical ultra-wideband channel model. IEEE document #02240r0p802-15-SG3a.
[10] Foerster J. Channel modeling sub-committee report final. IEEE P802.15-02/368r5SG3a, Dec.3, 2002.
[11] Park,K.Y., Performance evaluate of energy detectors, IEEE Transactions on Aerospace and Electronic systems, AES-14, Mar 1978, Page(s):237-241.
[12] L.科恩,白居宪译,时频分析:理论与应用阅,西安交通大学出版社,1998.
[13] Torrieri, D.J.,“Principles of Secure Communications Systems”, Boston: Artech House, 1992.
[14] Dillard.R.A.,“Detectability of spread-spectrum signals”, IEEE Transactions on Aerospace and Electronic Systems, AES-15, July 1979, Page(s):526-537.
[15] P.F.Mills, G.E.Prescott,“A comparision of various radiometer detection models”, IEEE trans, AES ,vol32,No.1, 1996, Page(s):468-473.
[16] I.H . Choi, J. W. Williams,“Improved Time-frequency Representation of Multicomponent signals Using Exponential”, IEEE Trans. Acoust., Speech, Signal Processing, vol37,1989, Page(s):862-871.
[17] [M].杨力华,戴道清,译,信号处理的小波引导,北京:机械工业出版社,2002.
[18] N.E.Huang, Z.Shen, S.R.Long, M.L.Wu, H.H.Shih, Q.Zheng, N.C.Yen, C.C.C.Tung, and H.H.Liu,“The empirical mode decomposition and Hilbert spectrum for nonlinear and nonstationary time series analysis”, proc.R.Soc.London A, vol.454, 1998, Page(s):903-995.
[19] N.E.Huang,“Computer Implicated Empirical Mode Decomposition Method”, Apparatus, and Article of Manufacture, U.S. Provisional Application, No.60/023,822,1996.
[20]冯学良,刘震,石星,“基于相关算法的脉冲信号”,电讯技术,第48卷第7期,2008年7月.
[21]陈国东,武穆清,“一种基于多频带PSWFs组合的CUWB自适应脉冲波形设计”,电子与信息学报,第30卷,第6期,2008年6月.
[22] FCC. Revision of Part 15 of the Commission’s Rules Regarding Ultra-Wideband Transmission Systems. First Report and Order, ET Docket 98-153, FCC 02-8, adopted/released Feb. 14/Apr. 22, 2002.
[23] Maria-Gabriella, Di Benedetto, Guerino Giancola. Understanding Ultra Wide Band Radio Fundamentals [M].America: Pearson Education, 2004.
[24] Dong-Ho Kim, Gyeong-Nam Bang, Chongdae Park,“Design and characteristics of high order derivative gaussian pulse generator for DS-UWB”Microwave Conference, 2006. APMC 2006. Asia-Pacific 12-15 Dec. 2006, Page(s):1110–1113.
[25] Xianren Wu, Zhi Tian, Davidson, T.N. , Giannakis, G.B.,“Optimal waveform design for UWB radios”, Signal Processing, IEEE Transactions on see also Acoustics, Speech, and Signal Processing, IEEE Transactions on Volume 54, Issue 6, Part 1, June 2006, Page(s):2009–2021.
[26] Cheng-Lin Cai, Xiao-Hui Li, Xin-Sheng Xu, Hai-Tao Wu,“A novel uwb pulse design method of optimizing combination with differential Gaussian pulse”Ultrawideband and Ultrashort Impulse Signals, 2008. UWBUSIS 2008. 4th International Conference on15-19 Sept. 2008, Page(s):228–230.
[27] Yue Wang; Xiaodai Dong; Fair, I.J.,“A Method for Spectrum Shaping and NBI Suppression in UWB Communications”, Communications 2006 IEEE International Conference on Volume 4,June 2006, Page(s):1476–1481.
[28]陶纯堪,陶纯匡,光学信息论[M].北京:科学出版社,2004,Page(s):1-10.
[29] Slepian, D.and Pollak, H.O.,“Prolate spheroidal wave functions, Fourier analysis and uncertainty”, I, Bell System Tech. J. 1961,40, Page(s):43-64.
[30] Tao Jiang; Zhen-gang Cui, Jia-wei Hu, Yan-li Hou,“A design of cognitive UWB pulse based on APSWF”Electromagnetic Compatibility and 19th International Zurich Symposium on Electromagnetic Compatibility, 2008. APEMC 2008. Asia-Pacific Symposium on 19-23 May 2008, Page(s):706–709.
[31] XIAO H, ROKLIN N, YARVIN N.,“Prolate spheroidal wave functions, quadrature and interpolation. Inverse Problems”, 2001, 17, Page(s):704-768.
[32] Rui Chen, Xiaoqing Zeng, Decun Dong,“Algorithm for UWB Pulse Design and its Performance Analysis”Integration Technology, 2007. ICIT '07. IEEE International Conference on 20-24 March 2007, Page(s):74–77.
[33] XIAO H, ROKLIN N, YARVIN N.,“Prolate spheroidal wave functions, Quadrature and interpolation. Inverse Problems”, 2001, 17, Page(s):805-838.
[34] Zhou Xiaofei, Zhang Honggang, Chlamtac Imrich,“Transmit power allocation among PSWF-based pulse wavelets in cognitive UWB radio”, Cognitive Radio Oriented Wireless Networks and Communications, 2006. 1st International Conference on 8-10 June 2006, Page(s):1–5.
[35] Liu Ping, Ning Jing,“UWB Pulse Design and capability analyze base on PSWF”, Microwave and Millimeter Wave Technology, 2007. ICMMT '07. International Conference on 18-21 April 2007, Page(s):1–3.
[36] Tao Jiang; Zhen-gang Cui, Jia-wei Hu; Yan-li Hou,“A design of cognitive UWB pulse based on APSWF”Electromagnetic Compatibility and 19th International Zurich Symposium on Electromagnetic Compatibility, 2008. APEMC 2008. Asia-Pacific Symposium on 19-23 May 2008, Page(s):706–709.
[37] Lu Yin, Zhu Hong-bo,“UWB pulse design method based on approximate prolate spheroidal wave functions.”, Journal on Communication, 2005, 26(10), Page(s): 60-64.
[38] Xu Yu-bin, Wang Fang, Sha Xue-jun, Doubly orthogonal PSWF pulse waveform design in UWB communication system. Journal of Harbin Institute of Technology, 2007, 39(1), Page(s):81-84.
[39]陈国东,“超宽带无线通信及若干关键技术的研究”,北京邮电大学博士论文,2007.6.
[40] J. Han and C. Nguyen,“A new ultra-wideband, ultra-short monocycle pulse generator with reduced ringing”, IEEE Microwave Wireless Compon. Lett., vol. 12, June 2002, Page(s):206–208.
[41] R. A. Scholtz,“Multiple access with time-hopping impulse modulation”, Proc. MILCOM93, Oct 1993, Page(s): 447–450.
[42] Zhendong Luo, Hong Gao, Yuanan Liu, Jinchun Gao,“A New UWB Pulse Design Method for Narrowband Interference Suppression”, Global Telecommunications Conference, 2004. GLOBECOM '04. IEEE Volume 6,29 Nov.-3 Dec. 2004, Page(s):3488–3492.
[43] L. Yang and G.B. Giannakis,“Ultra-Wideband Communications: An idea whose time has come”, IEEE Signal Processing Magazine21 (6) Nov. 2004, Page(s):26–54.