對於多輸入多輸出系統而言，採用時空碼(例如:時空區塊碼)在半靜態通道環境下可以得到不錯的系統效能。由於傳統採用時空區塊碼之多輸入多輸出分碼多工接取系統在非半靜態通道環境下會失去正交性導致系統效能大幅降低，通常需要額外的等化器來克服此問題，因此提升了系統的複雜度。為了降低系統在非半靜態通道環境下的解碼複雜度，吾人在本論文中提出ㄧ套具有正交與循環特性的多輸入多輸出分碼多工接取系統。
本系統是基於正交與循環的設計理念來降低解碼的複雜度及充分利用分集增益，並且針對不同傳輸率和分集增益的傳輸矩陣設計。此外，系統的錯誤率分析也一併在本論文中討論。
從分析和模擬結果，很明顯地可以發現我們所提出之系統利用簡單且低複雜度的最大相似法則解碼。其性能在半靜態的通道環境下能維持和傳統採用時空區塊碼之多輸入多輸出分碼多工系統一樣好；此外，在非半靜態的通道環境下能勝過傳統系統的效能。

For Multi-input-Multi-output (MIMO) systems, space-time coding such as Space-Time Block Codes (STBC) are taken to yield good performance in quasi-static channel. Unfortunately, conventional MIMO-CDMA with STBC will suffer from an error floor in non quasi-static channel and need an additional equalizer to combat this problem. So as to decrease the complexity of system, the novel orthogonal- and cyclic- inherent MIMO-CDMA systems are proposed in this thesis.
The proposed schemes which provide arbitrary transmission rate and diversity order for any number of transmit antennas with real or complex constellations are designed based on the orthogonal and cyclic concepts for simply decoding and fully taking the advantage of diversity. Furthermore, the upper bound analyses and the exact error probability for the proposed scheme are also derived.
Simulation results and performance analyses show that the proposed scheme can be decoded by a significant low complexity Maximum Likelihood(ML) decoder and remain similar performance as conventional MIMO-CDMA with STBC scheme in quasi-static channel; besides, it outperforms the conventional one as channel becomes non quasi-static.

[1] J. G. Proakis, Digital Communications, 4th edition, The McGraw-Hill Companies, Inc., 2001.
[2] S. Haykin, Communication systems, 4th edition, John Wiley & Sons, Inc., 2000.
[3] A. Paulraj, R. Nabar, and D. Gore, Introduction to Space-Time Wireless communications, Cambridge University Press, 2003.
[4] E. G. Larsson and P. Stoica, Space-Time Block Coding for Wireless Communications, Cambridge University Press, 2003.
[5] F. R. Farrokhi, G. J. Soschini, A. Lozano and R. A. Valenzuela, “Link-optimal space-time processing with multiple transmit and receive antennas,” IEEE Commun. Lett., vol. 5, no. 3, pp. 85-87, March 2001.
[6] G. J. Foschini, D. Chizhik, M. J. Gans, C. Papadias and R. A. Valenzuela, “Analysis and performance of some basic space-time architectures,” IEEE J. Select. Areas Commun., vol. 21, no. 3, pp. 303-320, March 2003.
[7] G. J. Foschini, “Layered space-time architecture for wireless communication in a fading environment when using multi-element antennas,” Bell Labs Tech. J., pp. 45-49, 1996.
[8] G. J. Foschini, G. D. Golden, R. A. Valenzuela and P. W. Wolnianski, “Simplified processing for high spectral efficiency wireless communication employing multi-element arrays,” IEEE J. Select. Areas Commun., vol. 17, no. 11, pp. 1841-1852, Nov. 1999.
[9] M. O. Damen, A. Chkeif and J. C. Belfiore, “Lattice codes decoder for space-time codes,” IEEE Commun. Lett., vol.5, no. 7, pp.304-306, July 2001.
[10] A. Wittneben, “Basestation modulation diversity for digital SIMULCAST,”in Proc. IEEE VTC’91, vol. 1, pp. 848-853, May 1991.
[11] A. Hiroike, F. Adachi and N. Nakajima, “Combined effects of phase sweeping transmitter diversity and channel coding,” IEEE Trans. Veh. Technol., vol. 41, no. 2, pp. 170-176, May 1992.
[12] N. Seshadri and J. H. Winters, “Two schemes for improving the performance of frequency-division duplex (FDD) transmission systems using transmitter antenna diversity,” Int. J. of Wireless Inform. Networks, vol. 1, pp. 49-60,1994.
[13] A. J. Paulraj and C. B. Papadias, “Space-time processing for wireless communications,” IEEE Signal Processing Mag., vol. 14, no. 6, pp. 49-83, Nov. 1997.
[14] G. V. Tsoulos, “Smart antennas for mobile communication systems,” Electron. Conmmun. Eng. J., vol. 11, no. 2, pp. 84-94, April 1999.
[15] P. H. Lehen and M. Pettersen, “An overview of smart antennas technology for mobile communication systems,” IEEE Commun. Surveys, vol. 2, no. 4, pp. 2-13, 4th Quarter 1999.
[16] D. H. Tuan and P. Russer, “Signal processing for wideband smart antenna array applications,” IEEE Microwave Mag., vol. 5, no. 1, pp. 55-67, March 2004.
[17] P. Balaban and J. Salz, “Optimum diversity combining and equalization in digital data transmission with applications to cellular mobile radio-Part I: Theoretical considerations,” IEEE Trans. Commun., vol.40, no. 5, pp. 885-894, May 1992.
[18] J. W. Liang and A. Paulraj, “A two-stage hybrid approach for CCI/ISI reduction with space-time processing,” IEEE Commun. Lett., vol. 1, no. 6, pp. 163-165, Nov. 1997.
[19] A. J. Viterbi, CDMA : Principles of Spread Spectrum Communication. Addison-Wesley Publishing Company, 1995.
[20] L. Hanzo, L. L. Yang, E. L. Kuan, and K. yen, Single- and Multi- Carrier DS-CDMA, Wiley, Inc. 2003.
[21] Z. Liu, X. Ma, and G. B. Giannakis, “Space-time coding and Kalman filter for time-selective fading channels,” IEEE Trans. Commu., vol. 50, no. 2, pp. 183-6, Feb. 2002.
[22] L. Wookbong and L. Inkyu, “Channel Equalization Technique for Space Time Block Codes in Non Quasi-Static Channels” IEEE VTC, vol. 3, no. 2, pp. 2215-9, Sept. 2004.
[23] F. C. Zheng and A. G. Burr, “Signal detection for non-orthogonal space-time block coding over time selective fading channels,” IEEE Commun. Lett., vol. 8, no. 8, pp. 491-3, Aug. 2004.
[24] K. S. Ahn, J. Y. Kim and H. K. Baik, “Bit error rate performance of decision feedback detection for space-time block coded systems over time-selective fading channels,” IEEE ICASSP, vol. 4, pp. 869-872, March 2005.
[25] C. E. Shannon, “A mathematical theory of communication”, Bell Syst. Tech. J., vol. 27, pp. 379-423, Urbana, 1949.
[26] A. B. Gershman and N. D. Sidiropoulos, Space-Time Processing for MIMO Communications, John Wiley & Sons, Inc., 2005.
[27] D. Durgin, Space-Time Wireless Channels, person education, Inc, 2003
[28] V. Tarokh, N. Seshadri and A. R. Calderbank, “Space-time codes for high data rate wireless communication: performance criterion and code construction”, IEEE Trans. Inform. Theory, vol. 44, no. 2, pp. 744-765, Mar. 1998.
[29] S. M. Alamouti, “A simple transmit diversity technique for wireless communications”, IEEE Jorunal Select. Area Commun., vol. 16, no.8, pp. 1451-1458, Oct. 1998.
[30] A. Wittneben, “A new bandwidth efficient transmit antenna modulation diversity scheme for linear digital modulation”, in Proc. IEEE ICC93, pp.1630-1634, 1993.
[31] V. Tarokh, H. Jafarkhani and A.R. Calderbank, “Space-Time Block Codes from Orthogonal Designs”, IEEE Trans. Inform. Theory, vol. 45, no. 5, pp.1456-1467, July 1999.
[32] A. V. Geramita and J. Seberry, Orthogonal Designs, Quadratic Forms and Hadamard Matrices, Lecture Notes in Pure and Applied Mathematics, vol. 43. New York and Basel: Marcel Dekker, 1979.
[33] W. C. Jakes, Microwave Mobile Communications, New York: John Wiley & Sons Inc, 1975.
[34] B. Walke, P. Seidenberg, and M. P. Althoff, UMTS The Fundamentals, John Wiley Inc, 2003.
[35] H. Holma and A. Toskala, WCDMA FOR UMTS Radio Access For Third Generation Mobile Communications, John Wiley Inc, 2000.
[36] Downlink improvement through space-time spreading, Lucent Technologies proposal 3GPP2-C30-19 990817-014 to the IS-2000 standard, Aug. 1999.
[37] Space-time block coded transmit antenna diversity for WCDMA, proposed TDOC #662/98 to ETSI SMG2 UMTS standards, Dec. 1998.
[38] I. Hen, “MIMO Architecture for wireless communication”, Intel Technology Journal, vol. 10, May 2006.
[39] E. Pakbaznia, and S. H. Jamali, “Performance Analysis of CDMA Multiuser Systems When Using Space-Time Block Coding and BPSK Modulation”, to appear in Proc. IEEE’ ISSSTA, Sept. 2004.
[40] E. Pakbaznia, and S. H. Jamali, “Analytical Performance Evaluation of Space-Time Block Coded CDMA Multi user Systems”, to appear in Proc. VETECF, Sept. 2004.
[41] R. E. Ziemer, Elements of Engineering Probability and Statistics, Prentice-Hall Inc, 1997.