臺灣博碩士論文加值系統

無線通道由於受到多重路徑干擾的影響而有嚴重的通道衰減，使用時間或頻率的分集為有效減輕衰減的技術。而多重輸入多重輸出系統除了可經由空間分集來抵抗通道的衰減，同時也能增加系統的能量，這些引發了空時碼的研究。空時碼結合了通道編碼與多傳輸天線而能有效應用於多路徑干擾之無線通道。
隨著現代化的數位系統與行動通訊系統中資料傳輸的機會慢慢增加，資料在傳輸過程保持正確變的越來越重要。因此錯誤更正碼也就扮演著越來越吃重的角色。而渦輪碼也因為它在白色高斯通道能逼近薛農極限而變成目前最受歡迎的錯誤更正碼之一。除此之外，渦輪碼也在第三代行動通訊系統中被採用當成標準。
在本篇論文裡，我們展示了在無線數位通訊裡一些應用的重要概念，例如像是串聯連結，渦輪碼，時間和天線分集。我們結合了渦輪碼與空時區塊碼並使用渦輪碼解碼演算法LogMAP演算法。最後，在空時區塊碼不同的正交矩陣之下，展現出我們的模擬結果。此外，還比較了在相同傳送天線數目，不同碼率的正交矩陣之下的比較圖。

The wireless channel suffers severe attenuation caused by multipath fading. The effective technique to mitigate multipath fading is to use the time or frequency diversity. The communication system with multiple input multiple output can combat the channel attenuation by spatial diversity and increase the channel information capacity. The principle of space-time coding schemes is to combine the concept of channel coding design and multiple transmit antennas, which are then effectively applied to multipath wireless channel.
Since the amount of data transfer of the modern digital or mobile communication is increasing, the reliability of the data transfer has become more and more important. Therefore, the error correction coding has played a very important role in wireless communication channel. The turbo code is one of the most popular error correction codes at present due to its good error correction ability. Besides, the turbo code is adopted in the 3G mobile communication standard.
In this thesis, we present the application of several important concepts of wireless digital communications, i.e., serial concatenation, turbo coding, and temporal and antenna diversity . We combine the turbo code and the space-time block code and use the LogMAP algorithm to implement the soft in/soft out decoding algorithms of turbo code. Finally, we present our simulation results under different encoding scheme of the space time block code. Furthermore, we also present the comparison of the simulation result under different rate of space-time block codes but the same number of transmit antennas.

1 Introduction 1
2 Space-Time Block Codes 3
2.1 Maximal Ratio Receive Combining (MRRC) …....……………………… 3
2.2 Alamouti’s Space-Time Block Codes ……………………………………. 6
2.1.1 Two-branch Transmit Diversity with One Receiver ……………... 6
2.1.2 Two-branch Transmit Diversity with Two Receiver …………...... 7

2.3 Tarokh’s Space-Time Block Codes ……………………………………… 11
3 Turbo Codes 18
3.1 Turbo Code Encoder …………………………………………………...... 18
3.1.1 The Structure of Turbo Code Encoder …………………………... 18
3.1.2 Puncturing of a Code …………………………………………….. 19
3.2 Turbo Code Decoder …………………………………………………….. 20
3.2.1 Principle of Turbo Code Decoder ……………………………….. 20
3.2.2 MAP and LogMAP Algorithm …………………………………... 21
3.3 Simulation Results of Turbo Codes ……………………………………... 29
4 STBC Concatenated with Turbo Codes 33
4.1 The Structure of STBC Concatenated with Turbo Code ………………… 33
4.2 Simulation Results ………………………………………………………. 34
5 Conclusion 43
Bibliography 44

[1]S. M. Alamouti, “A Simple Transmitter Diversity Scheme for Wireless Communi- cations,” IEEE J. Select. Areas Commun., vol. 16, pp. 1451-1458, Oct. 1998.
[2] V. Tarokh, H. Jafarkhani, and A. R. Calderbank, “Space-Time Codes for High Da- ta Rate Wireless Communication: Performance Criterion and Code Construction,” IEEE Trans. Inform. Theory., vol. 44, pp. 744-765, Mar. 1998.
[3] V. Tarokh, H. Jafarkhani, and A. R. Calderbank, “A Space-Time Coding Modem for High-Data-Rate Wireless Communications,” IEEE J. Select. Areas Commun., vol. 16, pp. 1459-1478, Oct. 1998.
[4] V. Tarokh, H. Jafarkhani, and A. R. Calderbank, “Space-Time Block Coding for Wi reless Communication: Performance Results,” IEEE J. Select. Areas Commun., vol. 17, pp. 451-460, Mar. 1999.
[5] V. Tarokh, H. Jafarkhani, and A. R. Calderbank, “Space-Time Block Cods from Orthogonal Designs,” IEEE Trans. Inform. Theory., to be published.
[6] Shu Lin, Daniel J. Costello, Error Control Coding, New Jerset, 2004.
[7] L. R. Bahl, J. Cocke, F. Jelinek, and J. Raviv, “Optimal Decoding of Linear Codes for Minimizing Symbol Error Rate,” IEEE Trans. Inform. Theory., IT-20: 284-87, Mar. 1974
[8] Junghoon Suh and M.M.K. Howlader, “Concatenation of turbo code with transmit diversity without channel estimation,” IEEE VTC, May 2002.
[9] Junghoon Suh and M.M.K. Howlader, “Design schemes of space-time block codes concatencated with turbo codes,” IEEE VTC, May 2002.
[10] T. H. Liew and Lajos Hanzo, “Space-time codes and concatenated channel codes for wireless communications” Proceedings of the IEEE, vol. 90, pp. 187-219, Feb. 2002.