本論文主要探討應用於都會型寬頻無線網路(WMAX)基頻收發機，並討論該收發機於高速環境下的影響與改進，其內容包含先前相關研究的研讀，系統模擬與架構設計，以及電路設計與實現。

本論文提出了一個使用空間-頻率區塊編碼方式之寬頻無線網路基頻收發機。本接收機最主要的是空間-頻率區塊解碼等化器來還原訊號經過高速通道環境的各種衰變。空間-頻率區塊解碼等化器主要是依據已得到的通道資訊使用最大比例結合(Maximum Ratio Combining)的方式將收到的訊號作線性組合以還原原始傳輸之訊號，並且使用一個平行干擾去除方法(Parallel Interference Cancellation)以消除鄰近子載波之間的頻率響應不匹配所造成的子載波干擾。這個空間-頻率區塊解碼等化器經由回授之方式重複降低子載波干擾。另外，為了增加通道的可靠性，本接收機使用了時域軸線性內插法以及頻域軸線性內插法把領航符元(pilot)的通道資訊用線性延伸 (Linear Extension) 的方法取得所有子載波之通道響應，使得空間-頻率區塊解碼等化器能依據頻率響應消除通道效應。

本論文中，系統模擬建立在ITU-VA的行動通訊通道，並且加上了加成性白高斯雜訊模型。同時依照Jakes頻譜進行靜態還有動態的通道模擬以探討本收發機在高速環境下之接收狀況。

另外為了加速演算法之開發與模擬，本收發機建構在一OFDM-MIMO的驗證平台。藉由此驗證平台，傳輸端等固定的部份將由硬體實現。接收端則是以C或SystemC進行模擬，並且將接收端演算法模組化，可方便使用者進行模組替換。同時可以與國立台灣大學電子工程研究所吳安宇教授實驗室開發之OFDM外收發機驗證平台，以及國立台灣大學電子工程研究所闕志達教授實驗室開發之OFDM-MIMO基頻通道模擬平台進行結合，串聯起整個基頻處理器以進行完整的模擬。

最後將整個平台建置於一圖形使用者介面網頁，能提供各地使用者進行模擬。

This thesis is focus on a MIMO-OFDM system, which uses space frequency block coding algorithm for high mobility environment. An inner transmitter and receiver for IEEE 802.16e uplink specification is designed to implement this algorithm. In order to model a high mobility environment, ITU-VA channel model, which is constituted by 3GPP, is used for the simulation. Additionally, Jakes model is added to simulate the high mobility environment.
Compare with space time block code and space frequency block code, space frequency block code has better performance in outdoor environment with high mobility. Thus,
this thesis propose a SFBC decoding algorithm to against Doppler effect. An 2x2 SFBC-OFDM is defined in IEEE 802.16e standard. The simulation result shows that Doppler effect can be alleviated through this algorithm. In general SFBC system, the adjacent channel responses are assumed constant. However, channel responses are not constant
in real communication systems, especially in high mobility environment. The variation between adjacent channel responses causes interference while decoding, so the error will occur in high SNR. Thus, an interference cancellation method is needed to solve this problem. The demapping result is sent back to the SFBC decoder for the interference
cancellation. The simulation result shows that this cancellation can prevent error floor in high SNR region.
In order to implement this system, we designed an inner transmitter platform for high speed emulation. This platform consist hardware part and software part. Some
complicated operations can be implement in hardware, so the emulation time can be reduced. Furthermore, the receiver is designed in software, so the user can change or replace the receiving method easily. If designer want to develop a new receiving algorithm, it can save the development time. Additionally, this platform is built on the webpage, so everyone can use this platform from anywhere through the internet.

[1] IEEE 802.16-2004, “IEEE Standard for Local and Metropolitan Area Networks Part 16: Air Interface for Fixed Broadband Wireless Access Systems,” Oct. 2004.

[2] IEEE 802.16e-2005, “IEEE Standard for Local and Metropolitan Area Networks
Part 16: Air Interface for Fixed and Mobile BroadbandWireless Access Systems
Amendment for Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands and Corrigendum 1,” Dec. 2005.

[3] http://www.techwarelabs.com/articles/other/wimax wifi

[4] Wei Bai, Lin Tang, and Zhiyong Bu, “An Equalization Method for OFDM in Time
Varying Multipath Channels,” in Proc. IEEE VTC, vol. 3, Sept. 2004, pp.1740 - 1743.

[5] K. F. Lee, and D. B Williams, “A space frequency transmitter diversity technique for OFDM systems,” in Proc. of Globlecom 2000, vol. 3, Nov. 2000, pp. 1473-1477.

[6] V. Tarokh, H. Jafarkhani, and A. R. Calderband, “Space time block coding for wireless communications: Performance result,” IEEE JSAC, vol. 17, no. 03, pp. 451-460, March 1999.

[7] J. Y. Kim, G. L. Stuber and I. F. Akyildiz, “Macrodiversity power control in hierarchical CDMA cellular systems, ” IEEE JSAC, vol. 19, no. 2, pp. 266-276,
Feb. 2001.

[8] G. Secin and D. H. Alexandra, “Performance analysis of space-time transmitter diversity techniques for WCDMA using long range prediction,” IEEE Truncations on Wireless Communications, vol. 4, pp. 40-45, Jan. 2005.

[9] S. Haykin, Communication Systems, 4th ed. John Wiley and Sons, 2001.

[10] C. E. Shannon, “A mathematical theory of communication,” Bell Labs Technical Journal, vol. 27, pp.379-423, 1948.

[11] Li Lihua, Yao Xiaofeng, Zhang Ping, and Harald Haas, “A practical space-frequency block coded OFDM scheme for fast fading broadband channels,” Indoor and Mobile
Radio Communications, The 13th IEEE International Symposium, vol. 1, 15-18 Sept. 2002.

[12] Gangyoul Yu, Joonhyuk Kang, “Quasi-orthogonal space-frequency block code,”Communications and Information Technology, vol.2, pp.979 - 982, Oct. 2004.

[13] T. Eng, N. Kong, and L. Milstein, “Comparison of diversity combining techniques for rayleigh-fading channels,” IEEE Transactions on Communications, vol. 44,
pp.1117-1129, September 1996.

[14] W. C. Jakes, Microwave Mobile Communications, New York: Wiley, 1974.

[15] Alamouti, S.M, “A simple Transmit Diverdity technique for Wireless Communications,” IEEE JSAC, Vol.16, No. 8, pp. 1451-1458, Oct. 1998.

[16] K. F. Lee and D. B. Williams, “A space-time coded transmitter diversity technique for frequency selective fading channels,” in Proc. of 2000 IEEE Sensor Array and
Multichannel Signal Processing Workshop, pp. 149 -152,2000.

[17] K. E Lee and D. B. Williams, “A space-frequency transmitter diversity technique for OFDM systems,” in Proc. IEEE Globlecom 2000, vol. 3, pp. 1473 -1477, 2000.

[18] Diniz, da Silva, and Netto, Digital Signal Processing, 1st ed. New York: Cambridge University Press, 2002.

[19] 3GPP TS 25.101, “Technical Specification Group Radio Access Network: User Equipment (UE) radio transmission and reception (FDD) (Release 7),” v7.0.0, June 2005.

[20] Dehghani M.J., Aravind R., Jam S., Prabhu K.M.M., “Space-frequency block coding in OFDM systems,” in Proc. IEEE TENCOM 2004, vol. 1, pp. 543-546, 2004.

[21] Lihong Jia, Yonghong Gao, Jouni Isoaho and Hannu Tenhunen, “A new VLSIoriented FFT algorithm and implementation,” ASIC Conference 1998. Proceedings.
Eleventh Annual IEEE International, pp. 337-341, 13-16 Sep. 1998.

[22] Y.W Lin, H. Liu and C. Lee, “A 1-GS/s FFT/IFFT Processor for UWB Applications,” IEEE JSSC , vol. 40, no. 8, pp. 1726-1735, Aug. 2005.