摘要
超宽带(UWB)无线通信技术具有传输速率高、功耗低、定位精度高、抗多径能力强等许多优点,已成为短距离无线通信领域研究与开发的热点。但是超宽带技术要走向成熟,还需要解决许多关键的技术问题,其中之一就是信号的同步问题。由于超宽带信号直接使用基带传输亚纳秒级的极窄脉冲,并且由于功耗的限制,信号淹没在噪声之中,同时又有本系统多用户干扰和其他窄带系统信号的干扰,接收信号如何准确同步就成为难点之一。
本文以UWB通信系统为背景,主要研究了UWB系统中同步捕获问题,提出了实现方案并予以仿真实现。首先介绍了超宽带通信的发展动态、基本原理,深入研究了典型的UWB通信系统方案及其调制技术,讨论了UWB通信的信道模型。接下来讨论了UWB系统的各种同步技术,最后分别提出了一种适用于DS-UWB系统的采用TDT算法与滑动相关相结合的同步捕获方案,以及一种适用于TH-UWB系统的基于跳时码整体同步的TH-UWB多用户系统同步方案,并通过仿真验证了这两种同步捕获方案用于UWB系统的可行性。
Since the Ultra Wideband (UWB) wireless communication has lots of advantages such as high data transmission rate, low power consumption, high precision location identification and inherently exceptional multipath immunity and so on, it has been the subject of extensive research in the short-range wireless communication area. But there are still some key problems need to be solved before the UWB technology comes into actual use, and one of these key points is synchronization. Since the carrier-less UWB system transmits the base-band, extremely narrow impulses on the sub-nanosecond order directly, the transmitted signals will hide in the noise environment due to the limitation of the signal power. And there exist multi-user interference from the system itself and the other narrowband systems. Accurate synchronization becomes one of the difficult techniques.
The subject of this thesis is the synchronization capture technology in UWB. And some realization scheme are proposed and simulated in this thesis. The basic theory of UWB communication is introduced at first. The system model and the modulation technology is then analyzed in detail, also the UWB channel model is discussed. Many synchronization schemes are illustrated and compared in succession. Finally two schemes are proposed, one is the improved Timing with Dirty Templates (TDT) coarse synchronization combined with slide correlation fine synchronization scheme used in the multi-user Direct Sequence spread spectrum UWB (DS-UWB), and the other is the synchronization scheme based on the entire Time Hopping (TH) code in the multi-user TH-UWB system. The simulation results show those two algorithms can capture the synchronization time in the UWB system efficiently.
引文
[1] 王金龙,王呈贵,阚春荣,徐以涛. 无线超宽带(UWB)通信原理与应用. 北京:人民邮电出版社,2005.
[2] 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.
[3] Tian Z, Giannakis G B. BER Sensitivity to Timing Offset in Ultra Wideband Communication. SPAWC 2003.4th IEEE Workshop, 2003, pp:234-238.
[4] Yoshiyuki Ishiyama, Tomoaki Ohtsuki. Performance Comparison of UWB-IR using Rake Receivers in UWB Channel Models, Ultra Wideband Systems. 2004, Joint with Conference on Ultrawideband Systems and Technologies, Joint UWBST & IWUWBS, 2004 International Workshop on, 18-21 May 2004 pp:226-230.
[5] Christine Uhl, Christophe Le Martret. Jamming Assessment of Impulse UWB Signals on Galileo Receivers, Ultra Wideband Systems, 2004. Joint with Conference on Ultrawideband Systems and Technologies. Joint UWBST & IWUWBS. 2004 International Workshop on, 18-21 May 2004 pp:55-59.
[6] Birgit Kull, Sven Zeisberg. UWB Receiver Performance Comparison, Ultra Wideband Systems, 2004. Joint with Conference on Ultrawideband Systems and Technologies. Joint UWBST & IWUWBS. 2004 International Workshop on 18-21 May 2004 pp:21-25.
[7] Qinghua Li and Leslie A.Rusch. Multiuser Detection for DS-CDMA UWB in the Home Environment, IEEE Journal on selected areas in communications, vol.20, no.9, Dec 2002, pp:1701-1710.
[8] M.K. Simon, J.K. Omura, R.A. Scholts. 扩频通信技术教程(英文版). 北京:人民邮电出版社, 2002.
[9] Win M Z, Scholtz R A. Impulse Radio:How it Works. Communications Letters, IEEEE.1998.2(2),pp:36-38.
[10] S. Vijayakumaran, T.F. Wong. Equal Gain Combining for Acquisition of UWB Signals.IEEE Military Communications Conference (MILCOM’03), 2003,2 (10), pp:880-885.
[11] S. Soderi, J. Iinatti, M. Hamalainen. CLPDI Algorithm in UWB Synchronization. Proc. of International Workshop on Ultra Wideband Systems, 2003, 6 (2), pp:759-763.
[12] Sandeep R.Aedudodla,Saravanan Vijayakumaran, tan F.Wong. Timing Acquisition in Ultra-wideband Communication systems. IEEE Transaction on Vehicular Technology, vol54, no 5,2005, pp:1570-1583.
[13] Tian Zhi, G. B. Giannakis. Data-aided ML Timing Acquisition in Ultra-wideband Radios.UWB ST2003, 2003, pp:142-146.
[14] Yang L, Giannakis G B. Blind UWB Timing with A Dirty Tempalte. Acoustics, Speech and signal Processing, 2004(ICASSP'04).IEEE International conference, 2004,4, pp:509-512.
[15] Liuqing Yang, Georgios B. Giannakis. Timing Ultra-Wideban Signals With Dirty Tempaltes, IEEE Transactions on communications,vol.53,no11,2005, pp:1952-1963.
[16] 刘磊,向新,田红心,易克初. 一种适用于 PAM-UWB 系统的同步算法. 电子科技,2006 年第 1 期,pp:33-35.
[17] 汪一鸣,朱洪波. 一种基于自适应的 DS-UWB 同步方法捕获方法. 电子学报,2007 年 6 月,第 35 卷第 6 期,pp:8-42.
[18] [意]Maria-Gabriella 等著;葛利嘉等译. 超宽带无线电基础. 北京:电子工业出版社,2005.
[19] 姜丹. 信息论与编码. 合肥:中国科学技术大学出版社,2004.
[20] M. Z. Win and R. A. Scholtz. Ultra wide bandwidth time hopping spread- spectrum Impulse Radio for wireless multiple access communications.IEEE Trans. on Communications, vol. 48, no. 4, April 2000, pp:679-691.
[21] 段吉海,郑继禺,仇洪冰,林基明. UWB 通信系统的 TH-PPM 信号产生与接收处理. 桂林电子工业学院学报,2005.6, pp:22-24.
[22] R.A.Scholz. Multiple-access with timehopping impulse radio modulation. in Proc. of MILCOM'93, montreat,1993,pp:447-450.
[23] I Ramachandran, S Roy. Acquisition of direct-sequence ultra-wideband signals. IEEE Wireless Communications and Networking Conference.2005, pp:752-757.
[24] John G Proakis. Digital Communications (4edition). New York,USA: The McGraw-Hill Companies,Inc, 2001.
[25] M.Z.Win, R.A.Scholtz.Charaterization of ultra-widebande wireless indoor channels: a communication-theoretic view. JSAC,VOL20,Dec.2002, pp:1613-1627.
[26] Jeffrey R. Foerster.The Effects of Multipath Intereference of the Performance of theUWB System in an Indoor Wireless channel. VTC, 2001spring.
[27] Moe Z.Win, Fernando ramirez-Mireles, Robert A,Scholtz. Ultra-Wide Bandewidth (UWB) Signal Propagation for outdoor Wireless Communications. VTC'97,VOL1, pp:967-977.
[28] J.Foerster et al. Channel modeling sub-committee report final, IEEE 802.15 wireless Personal Area Networks.p802.15-02/490rl-SC3a, Feb.2003.
[29] Jac Romme, Klaus witrisal. Transmitted Reference UWB System Using Weighted Autocorrelation Receivers, IEEE Transaction on Microwave Theory and Techniques, VOL54,NO.4,2006, pp:1754-1761.
[30] J.Zhang, T.D. Abhayapala, R.A.Kenedy. Performance of ultra wideband correlator receiver using gaussian monocycles, 2003-IEEEInternational Conference on Communication,VOL.216,NO.1,2003, pp:2192-2196.
[31] Deqiang Wang, Danpu Liu. Performance Comparison of Two Kinds of UWB Rake Receiver ,IEEE 6th CAS Symp. on Energing technologies,2004, pp:329-332.
[32] Qinghua Li, Leslie A.Rusch. Multiuser receicers for DS-CDMA UWB. 2002 IEEE conf. on ultra wide band systems and technologies, pp:163-168.
[33] 唐建锋,汪一鸣. 基于自适应的 DS-UWB 多用户检测方案的研究. 微电子学与计算机,2005 年第 22 卷,第 9 期,pp:127-129.
[34] 何振亚. 自适应信号处理. 北京:科学出版社,2002.
[35] 樊昌信,张甫翊,徐炳祥,吴成柯. 通信原理. 北京:国防工业出版社,2004.
[36]Irena Maravi'c, Julius Kusuma, Martin Vetterli. Low-Sampling Rate UWB Channel Characterization and Synchronization, 1229-2370/99/$10.00c_2002 KICS.
[37] Carbonelli C,Mengali U, Aitra U. Synchronization and Channel estimation for UWB signal.Global Telecommunications Conference, IEEE Communications Society, 2003, pp:764-768.
[38] E. A. Homier and R. A. Scholtz. Rapid acquisition of Ultra-Wideband signals in the dense multipath channel. IEEE Conference on Ultra Wideband Systems and Technologies, Baltimore, MD, USA, May 20-23, 2002, pp:105–110.
[39] R.L.Peterson, R.E.Ziemer, D.E.Borth. An Introduction to Spread Spectrum Communications.upper Saddle River, NJ:Prentice-Hall,1995.
[40] Sandeep R.Aedudodla, Saravanan Vijayakumaran. Timing Acquisition in Ultra-Wideband Communication Systems. Wireless Information Networking GroupUniversity of Florida,Mar3, 2005.
[41] Z. Tian, V. Lottici. Efficient timing acquisition in dense multipath for UWB communications.in Proc. 2003 IEEE Vehicle Technology Conf.,2003, pp:1318-1322.
[42] Z. Tian, L. Yang, G. B. Giannakis. Non-data aided timing-offset estimation for Ultra-Wideband transmissions using cyclostationarity. IEEE Trans. on Communications, submitted March 2003.