中文摘要
隨著行動通訊人口的與日俱增，如何有效地利用有限的頻帶與加強通訊品質，一直是所有專家學者相當關心的課題。因為展頻技術具有抗干擾，抗多重路徑衰減等優越能力，過去一直在軍用通訊上扮演相當重要的角色。而近年來，更進一步應用在商業通訊方面，如分碼多重擷取(CDMA)系統，便是以展頻技術為基礎的通訊方式。
另一方面，現在的學者們也提出，將天線陣列的技術應用於CDMA通訊系統上，將有效地改善許多目前無線通訊遭遇的難題。且因為適應性天線陣列，具有隨外在環境改變參數的功能，故又名之為「智慧型天線」。而智慧型天線主要有兩種形式：「切換波束系統」和「追蹤波束系統」。其中切換波束系統有一些固定的波瓣，而行動台可選擇一個接收訊號性能較好的波瓣，這種系統的結構較為簡易。另一種追蹤波束系統，可即時調整天線陣列的權重，使得波瓣能夠持續追蹤所欲行動台，並且同時將干擾消除，這種系統結構較為複雜，但SINR較高，為本論文主要探討對象。
近來有許多在CDMA系統下的智慧型天線追蹤波束系統被提出，本論文所提的架構主要分為角度追蹤和動態波束構成兩方面。利用改良式遞迴更新法，和卡門濾波器來執行角度追蹤的功能，再根據追蹤到的角度，藉由MVDR波束構成技術來將主波瓣對準所欲行動台，並且同時抑制其他行動台所發出的干擾訊號。此外，我們更充分運用CDMA的特性，建立一個行動台數目可大於天線陣列感測器數目的智慧型天線。電腦模擬證實了所提出系統性能的優越性。

Abstract

Because of the rapid development of mobile communications, the bandwidth efficiency and the communication quality have become interesting issues for researchers. Multipath fading and multiple-access interference (MAI) are the main barriers of performance improvement. Fortunately, spread spectrum techniques have an inherent ability of anti-interference and anti-multipath. Thus, the commercialized CDMA systems are developed on the basis of spread spectrum techniques.
Recently, smart antennas using adaptive array techniques have been applied in CDMA communications. There are two different approaches to realize smart antenna systems: one is named as ‘switching-beam arrays’; the other is called ‘tracking-beam arrays’. Switching-beam arrays use a number of fixed beams at an antenna site. The mobiles select the beam that offers the best signal enhancement and interference reduction. On the other hand, tracking-beam arrays can adjust their pattern to track desired signals, reduce interference, and collect correlated multipath power.
In this thesis, several smart antenna systems based on tracking-beam arrays in DS-CDMA systems are developed. The proposed smart antennas comprise two main structures, i.e., the direction-of-arrival (DOA) tracking and the dynamic beamforming. The improved recursively updated method and the Kalman filter algorithm are employed to track the mobiles’ DOAs. By referring to the estimated DOA, the minimum- variance-distortionless-response (MVDR) dynamic beamformer produces a main beam to target on a certain mobile and simultaneously, interferences from other mobiles are suppressed. Therefore, the MAI in DS-CDMA systems can be suppressed properly at all times. Besides, the inherent processing gain in DS-CDMA systems is utilized to break through the limit that the number of mobiles must be smaller than that of sensors. The proposed smart antennas work properly even the number of mobiles exceeds that of sensor. Simulation results show that the advantages of the proposed technique over the conventional tracking-beam arrays.

目錄 頁次
感謝詞…………………………………………...………..………...i
中文摘要…………………………………………...…………….....ii
英文摘要…………………………………………….……..…….....iii
目錄…………………………………………………………………v
圖表目錄……………………………………………………………vii
第一章 緒言…………………………………………………..…...1
1.1 文獻探討……………………………………………..…...1
1.2 研究動機…………………………………………….……4
第二章 CDMA系統下天線陣列訊號模型……….……….…..…6
2.1 虛擬雜訊序列……………………………………….……..6
2.2 CDMA系統下線性陣列訊號模式……………………...…7
第三章 改良式遞迴更新法於智慧型天線之應用..………….……13
3.1 改良式遞回更新法於多目標角度追蹤……….….….……13
3.2 追蹤波束系統的實現..……………………….….…….…..16
3.3 電腦模擬……...…….…………………....…………….…..17
第四章 卡門濾波器於智慧型天線之應用……………...……..……24
4.1卡門濾波器於多目標角度追蹤…………………..…….….24
4.2 追蹤波束天線陣列的實現….…………………..………….28
4.3電腦模擬………….…………………………………..…….29
第五章 利用CDMA系統特性突破天線陣列維度限制………..….44
5.1追蹤波束系統的改良…………………………………...….45
5.1.1 經過解展頻後的天線陣列訊號模型……………….45
5.1.2 智慧型天線演算法的修正………………………….47
5.1.3 修正後追蹤波束系統的實現……………………….50
5.2 尋找最大特徵值的追蹤波束系統…………………….….51
5.2.1 共軛梯度法………………………………………….53
5.2.2 Lagrange’s multiplier………….…………………...56
5.3電腦模擬………….………………………………….…….57
第六章 討論與建議………………………………………………...71
參考文獻………………………………………………..…………...73
附錄A…………………………………………………………….…77
縮寫……………………………………………………………….…79

參考文獻
[1]M. Chryssomallis, “Smart antennas,” IEEE Antennas and Propagation, Vol.42, No.3, pp. 129-138, June 2000.
[2]S. Choi, D. Shim, and Tapan K. Sarkar, “A comparison of tracking-beam arrays and switching-beam arrays operating in a CDMA mobile communication channel,” IEEE Antennas and Propagation, Vol.41, No.6, pp.10-22, December 1999.
[3]R. O. Schmidt, ”Multiple emitter location and signal parameter estimation,” IEEE Trans. On Antennas Propagation, Vol.AP-34, pp.276-281, March 1986.
[4]R. Roy, A. Paulraj and T. Kailath, “Direction- of-arrival estimation by subspace rotation method-ESPRIT,” IEEE Proc. ICASSP, pp.2495-2498,1986.
[5]L. Ng and Y. Bar-Shalom, “Multisensor multitarget time delay vector estimation,” IEEE Trans. On Acoustics, Speech and Signal Processing, vol. ASSP-34, pp.669-677, AUG.1986.
[6]J. Yang and M. Kaveh, “Adaptive eigensubspace algorithms for direction or frequency estimation and tracking,” IEEE Trans. on Acoustics ,Speech and Signal Processing , vol. ASSP-36, pp.241-251, FEB.1988.
[7]C. R. Sastry ,E. W. Kaman ,M.Simaan, “An efficient Algorithm for Tracking the Angles of Arrival of Moving Targets,” IEEE Trans. on Signal Processing, vol.39, no.1, pp.242-246, JAN.1991.
[8]連彥宗，”多目標方位角度追蹤,”國立中山大學電機工程研究所碩士論文，MAY,1993.
[9]C. K. Sword, M. Samaan and E. W. Kamen, “Multiple Target Angle Tracking Using Sensor Array Outputs,” IEEE Trans. on Aerospace and Electronics Systems, vol.26 , no.2, pp.367 -373, MAR.1990.
[10]K. W. Lo and C. K.Li, “An Improved Multiple Target Angle Tracking Algorithm,” IEEE Trans. on Aerospace and Electronics Systems, vol.28, no.3, pp.797-805, JUL. 1992.
[11]S. B. Park, C. S. Ryu and K. K. Lee, “Multiple target angle tracking algorithm using predicted angles,” IEEE Trans. on Aerospace and Electronics Systems, vol.30, no.2, pp.643-648, APRIL 1994.
[12]Barry D. Van Veen and Kevin M. Buckley, “Beamforming: A Versatile Approach to Spatial Filtering,” IEEE ASSP Magazine, APRIL 1988.
[13]S. Choi and D. Yun, “Design of adaptive antenna array for tracking the source of maximum power and its application to CDMA mobile communication,” IEEE Trans. on Antennas and Propagation, Vol. AP-45, No.9, pp.1393-1404, September 1997.
[14]D. Shim and S. Choi, “A new blind adaptive algorithm based on lagrange’s formula for a real-time design of a smart antenna,” Proceedings of the IEEE Vehicular Technology Conference VTC98, Ottawa, Ontario, Canada, 1998.
[15]S. Choi, “Signal processing apparatus and method for reducing the effects of interference and noise in wireless communications utilizing antenna array,” US Patent No. 5,808,913.
[16]D. Shim and S. Choi, “A new blind adaptive algorithm for a real-time design of a smart antenna,” Telecommunications Review, 7, 5, pp.661-669, October 1997. (in Korean)
[17]S. Choi and D. Shim, “A novel adaptive beamforming algorithm for a smart antenna system in a CDMA mobile communication environment,” IEEE Trans. on Vehicular Technology, Vol. 49, No.5, Sep. 2000.
[18]S. Choi, “A signal processing method utilizing an eigenvector corresponding to the maximum eigenvalue of an autocorrelation matrix of received signals for an antenna array system,” Patent pending, PCT/KR97/0012.
[19]A. H. El Zooghby, C.G. Christodoulou, M. Georgiopoulos, “A neural network-based smart antenna for multiple source tracking,” IEEE Trans. on Antennas and Propagation, Vol.48, No. 5, May 2000.
[20]Arruda Filho, E.J.M. and Cavalcante, G.P.S., “A neural adaptive beamforming system to reduce interfering signals in mobile communications,” Microwave and Optoelectronics Conference, 1999. SBMO/IEEE MTT-S, APS and LEOS -IMOC '99. International, Vol.2, pp.658-662, 1999.
[21]S. Haykin, Communication Systems, New York: Wiley, 1994.
[22]H. Liu and M. D. Zoltowski, “Blind Equalization in Antenna Array CDMA System,” IEEE Transactions on Signal Processing, VOL.45, NO. 1, JAN. 1997.
[23]S. Choi, T. K. Sarkar, and J.Choi, “Adaptive antenna array for direction-of-arrival estimation utilizing the conjugate gradient methods,” Signal Processing, VOL.45, pp. 313-327, 1995.
[24]T. K. Sarkar, X. Yang, and E. Arvas, “A limited survey of various conjugate gradient methods for solving complex matrix equations arising in electromagnetic wave interactions,” Wave Motion. Amsterdam, The Netherlands: Elsevier Sci., pp.527-546, 1988.
[25]D. H. Johnson and S. DeGraaf, “Improving the resolution of bearing in passive sonar arrays by eigenvalue analysis,” IEEE Trans. Acoust., Speech, Signal Processing, VOL. ASSP-30, pp.638-647, Aug. 1982.
[26]H. Chen, T. K. Sarkar, S. A. Dianat, and J. D. Brul, “Adaptive spectral estimation by the conjugate gradient method,” IEEE Trans. Acoust., Speech, Signal Processing, VOL. ASSP-34, pp.272-284, Apr. 1986.
[27]J. S. Thompson, P. M. Grant, and B. Mulgrew, “Smart Antenna Arrays for CDMA Systems,” IEEE Personal Communications, VOL.3, NO.5, pp.16-25, Oct. 1996.