臺灣博碩士論文加值系統

摘要

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緩衰減的技術。Foschini與Gans及Telatar證明了多重輸入多重輸出系統除了可以經由空間分集來抵抗通道的衰減，同時也能增加系統的容量，這些研究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設計而能有效應用於多路徑干擾之無線通道。
Tarokh提出了時空籬柵碼(Space Time Trellis Codes)，在給定數目的天線條件下，能獲得最佳分集增益與一些編碼增益。另一方面由Berrou所提出的渦輪碼有非常強大的錯誤更正能力，將渦輪碼設計於多重傳輸天線是很不錯的編碼架構，如何能設計出具有最佳分集增益與優越除錯性能的時空渦輪碼仍是個開放的課題。
渦輪碼有兩個缺點，第一是於高訊雜比時，所發生的錯誤地板現象，第二是MAP解碼演算法具非常大的計算複雜度，Pyndiah將渦輪碼中反覆解碼的觀念，用於乘積碼(Product Code)中，稱之為渦輪乘積碼，渦輪乘積碼改進傳統渦輪碼的缺點，因此將渦輪乘積碼與多重傳輸天線結合，應能設計出性能良好，有效應用於無線通道的編碼系統。

Abstract
The multipath wireless channel suffers severe attenuation. The Effective techniques to mitigate multipath fading are time and frequency diversity. Foschini,Gans and Telatar proved that multiple input multiple output can introduce spatial diversity and increased information capacity. These results have motivated a new area in error correcting codes . Space-Time Coding (STC) schemes can combine the channel code design and the use of multiple transmit antennas .

The Space Time Trellis Codes (STTC) proposed by Tarkoh combine the trellis coding with symbol mapping into multiple transmit antennas . The Coding scheme expansion is done in antenna space. The Turbo Codes proposed by Berrou have powerful error correcting abilities. It would be benefit to design turbo codes for multiple antenna systems. To design space-time turbo codes with maximum space diversity and outstanding performance is still an open question.

The Turbo Codes exhibited a troublesome error floor. Besides, the MAP algorithm which performs maximum likelihood bit estimation has a very large computation complexity . Recently turbo product codes (TPC) have been proposed . It can proved the performance of turbo codes. It is expected that TPC for multiple antenna systems would be powerful coding schemes with maximum diversity gain and large coding gain.

目 錄
摘要……………………………………………………………………Ⅰ
Abstract……………………………………………………………… Ⅱ
誌謝……………………………………………………………………Ⅲ
目錄……………………………………………………………………Ⅳ
圖表索引………………………………………………………………Ⅵ
第一章 緒論……………………………………………………………1
第二章 時空區段碼……………………………………………………3
2-1分集……………………………………………………………4
2-1.1 空間分集……………………………………………4
2-1.2 頻率分集……………………………………………4
2-1.3 時間分集……………………………………………5
2-2 時空區段碼系統模型………………………………………5
2-2.1時空區段編碼………… ………………………6
2-2.2時空區段解碼……………………………………6
2-3 Alamouti時空區段碼……………………………………7
2-4 設計理論…………………………………………………9
2-5 時空區段編碼與正交矩陣設計……………………………13
2-5.1 時空區段編碼與實數正交矩陣………………13
2-5.2 時空區段編碼與一般化實數正交矩陣………14
2-5.3 時空區段編碼與複數數正交矩陣……………16
第三章 渦輪乘積碼…………………………………………………19
3-1 乘積碼………………………………………………………19
3-1.1 乘積編碼…………………………………………19
3-1.2 乘積碼的性質……………………………………20
3-2 Chase 演算法………………………………………………21
3-3 軟式解碼…………………………………………………26
3-3.1可靠度……………………………………………26
3-3.2 軟式輸出…………………………………………27
3-4 渦輪乘積碼………………………………………………29
3-4.1軟式判斷…………………………………………29
3-4.2 渦輪乘積解碼……………………………………30
第四章 渦輪乘積碼與時空區段聯結碼……………………………32
4-1渦輪乘積碼與時空區段碼聯結架構………………………32
4-2 模擬結果………………………………………………………33
第五章 結論…………………………………………………………38
Reference……………………………………………………………39
附錄…………………………………………………………41
作者簡介…………………………………………………………45

圖表索引
圖2.1 時空區段碼系統模型……………………………………………6
圖2.2 Alamouti 時空區段編解碼架構………………………………7
圖2.3 多傳輸天線比較圖……………………………………………17
圖3.1 乘積編碼架構……………………………………19
圖3.2 乘積編碼 …………………………………………20
圖3.3 Chase演算法解碼流程……………………………………22
圖3.4 BPSK信號群…………………………………………………23
圖3.5 錯誤樣本 E…………………………………………………24
圖3.6 測試樣本 T…………………………………………………24
圖3.7 候選字碼 …………………………………………………25
圖3.8 渦輪乘積解碼架構…………………………………………30
圖4.1渦輪乘積解碼與時空區段連結架構………………………32
圖4.2高斯衰減通道下BCH(31,26)2與 聯結碼……………………34
圖4.3高斯衰減通道下BCH(31,21)2與 聯結碼……………………34
圖4.4高斯衰減通道下BCH(63,45)2與 聯結碼……………………35
圖4.5高斯衰減通道下BCH(63,51)2與 聯結碼……………………35
圖4.6高斯衰減通道下BCH(127,113)2與 聯結碼…………………36
圖4.7 高斯衰減通道下BCH(63,57)2與 聯結碼…………………36
圖4.8 高斯衰減通道下BCH(127,120)2與 聯結碼………………37
圖4.9 高斯衰減通道下BCH(255,247)2與 聯結碼………………37
表 3.1不同碼率的乘積碼……………………………………………21

Reference
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[2] I. E.Telatar,”Capacityof multi-antenna gaussianchannels ”Eur. Trans. Telecommun ,vol0,no.6 ,pp.585-595,Nov.1999.

[3] 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, vol44,pp.744-765,Mar. 1998

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[12] D. Chase, “A class of algorithms for decoding block codes with channel measurement information,” IEEE Trans. Inform. Theory, vol. IT-18, pp.170–182, Jan. 1972.
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