近年來無線區域網路系統因對於提高資料速率以及降低錯誤率之需求，MIMO-OFDM已成為下一代無線區域網路之技術。本論文根據World Wide Spectrum Efficiency (簡稱WWiSE）聯盟提出之下一代無線區域網路標準 IEEE 802.11n提案，模擬一2X2 MIMO-OFDM系統，並以VHDL設計其硬體架構。
在本論文中，系統採用STBC編碼，包含封包偵測、符元時序同步、載波頻率同步、以及通道估測等模組，將先分別介紹其各模組之演算法並探討其效能，而最後整體系統經由電腦模擬結果顯示，所提出之MIMO-OFDM系統相較於傳統之IEEE 802.11a系統，在室內多通道路徑下性能將有顯著之提升。

Because of the demand of higher transmission data rate and better transmission quality, the MIMO-OFDM technology is the trend of the next-generation WLANs. In the thesis, we design a MIMO-OFDM baseband transceiver with two transmit antennas and two receive antennas based on the WWiSE（World Wide Spectrum Efficiency）Alliance’s IEEE 802.11n proposal. Then the architecture is implemented by VHDL.
In this thesis, an STBC-OFDM system is described, including the functions of frame detection, symbol timing synchronization, carrier frequency synchronization, and channel estimation. First, each block is discussed individually and the performance is analyzed. Finally, from the system-level simulation results, we show that the proposed MIMO-OFDM receiver offers better performance than the IEEE 802.11a system in an indoor multipath channel.

[1] “Orthogonal Frequency Division Multiplexing,” U.S Patent No.3, 488, 4555, filed Nov.14, 1966, issued Jan.6, 1970.
[2] S.B.Weinstein and P.M.Ebert,” Data Transmission by Frequency-Division Multiplexing Using the Discrete Fourier Transform,” IEEE Trans. Commun, vol. 19, pp.628-634,Oct.1971.
[3] R,van Nee and R.praasad,OFDM for Wireless Multimedia Communications,Boston/London:Artech House,1999.
[4] John Terry and Juha Heiskala, OFDM Wireless LANs: A Theoretical and Practical Guide. Indianapolis, Indiana: Sams, 2002.
[5] T.S.Rappaport, Wireless Communications: Principles and Practice, Prentice Hall, 1996.
[6] A. Wittneben, “Base station modulation diversity for digital SIMULCAST,” Proc. 1991 IEEE Vehicular Technology Conf. (VTC 41st), pp. 848–853, May 1991.
[7] V. Tarokh, N. Seshadri, and A. R. Calderbank, “Space-time codes for high data rate wireless communication: Performance criteria and code construction,” IEEE Trans. Inform. Theory, vol. 44, Mar. 1998.
[8] S. M. Alamouti, “A simple transmit diversity scheme for wireless communications, “IEEE J. Select. Areas Commun., vol. 16, pp. 1451-1458, Oct. 1998.
[9] V. Tarokh, H. Jafarkhani, and A. R. Calderbank, “Space–time block codes from orthogonal designs,”IEEE Trans. Inform. Theory, vol. 45, pp. 1456–1467, July 1999.
[10] P. W. Wolniansky, G. J. Foschini, G. D. Golden, and R. A. Valenzuela, ”V-BLAST: an architecture for realizing very high data rates over the rich-scattering wireless channel,” International Symposium on Signals, Systems, and Electronics, pp. 295-300, Sep. 1998.
[11] WWise Proposal: High throughput extension to the 802.11 Standard, Jan. 06,2005.
[12] T,M.Schmidl,D.C.Cox,“ Low-overhead, low-complexity burst synchronization for OFDM,” IEEE International Conference on Communications, vol. 3, pp. 1301-1306, June 1996
[13] Schenk, T.C.W.; van Zelst, A.; “Frequency synchronization for MIMO OFDM wireless LAN systems”, IEEE Vehicular Technology Conf. 2003-fall, vol 2, 6-9, pp. 781 – 785, Oct. 2003.
[14] Y. (G.) Li, N. Seshadri and S. Ariyavisitakul, “Channel estimation for OFDM systems with transmitter diversity in mobile wireless channels, “ IEEE J. Select. Areas Commun., vol. 17, pp. 461-471, Mar. 1999
[15] W. G. Jeon, K. H. Paik, and Y. S. Cho, “An efficient channel estimation technique for OFDM systems with transmitter diversity,” IEICE Trans. Commun., vol. E84-B, no. 4, pp. 967-974, April 2001.
[16] Slimane Ben Slimane,”Channel estimation for HIPERLAN/2 with transmitter diversity,” ICC 2002 - IEEE International Conference on Communications, vol. 25, no. 1, pp. 26 – 30,April 2002,
[17] R. Andraka, “A survey of CORDIC algorithms for FPGA based computers,” ACM/SIGDA 6th International Symposium of FPGA, pp. 191– 200, Feb 1998.