渦輪格架式編碼調變與渦輪等化器之結合在無線通訊之應用

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研究生：	彭俊豪 Jun-Hua Peng
論文名稱：	渦輪格架式編碼調變與渦輪等化器之結合在無線通訊之應用 Combination of Turbo Trellis Coded Modulation and Turbo Equalization for Wireless Communication
指導教授：	賴坤財 Kuen-Tsair Lay
口試委員:	方文賢 Wen-Hsien Fang 李大嵩 Ta-Sung Lee
學位類別：	碩士 Master
系所名稱：	電資學院 - 電子工程系 Department of Electronic and Computer Engineering
論文出版年：	2007
畢業學年度：	95
語文別：	英文
論文頁數：	61
中文關鍵詞：	無線衰減通道、渦輪格架式編碼調變、渦輪等化器
外文關鍵詞：	fading channel, turbo trellis-coded modulation, turbo equalization
相關次數：	點閱：259 下載：1
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由於通訊技術發展迅速,通訊模式從有線傳輸演變到無線傳輸。無線通訊已成為現今行動通訊中的一大熱門議題。對於資料在無線通道中傳輸，將面對雜訊影響和多路徑衰減干擾的問題，等化技術與通道編碼是傳輸系統中必要的應用。
在本論文中，我們使用考慮了一種利用等化器與解碼器所組成的迭代系統，可稱為渦輪等化器。且經由電腦模擬驗證上述所有技術在多路徑衰減通道中可有效的提高效能。在通道編碼方面,採取渦輪格架式編碼調變來對輸入訊號進行編碼。編碼訊號傳輸於無線衰減通道中,在接收端使用渦輪等化器來結合格狀式等化器及解碼器。由於等化器外部資訊是針對傳輸訊號且解調器是針對輸入訊號,所以等化器與解調器之間的外部資訊並無法互相利用。在本篇論文等化器與解調器都是軟進軟出(soft-in-soft-out)的系統,我們使用幾種方式來幫助轉換彼此的外部資訊,讓彼此的外部資訊轉換對方的軟資訊。由於等化器的計算量較大,所以我們也試著使用T-BCJR演算法來降低等化器的計算量。

Because of the rapid and widespread development of communication technique, transmission style has developed from wire communication to wireless communication. Wireless communication has become a popular topic in recent mobile communication.
It is necessary that we apply channel equalization and channel coding techniques in data transmission when we transmit data in multi-path fading channels, which typically suffer serious signal degradation.
In this thesis, we consider an iterative system, turbo equalization, which consists of equalization and decoding. Finally, the performances of these techniques mentioned above are evaluated by computer simulation in multi-path fading channels
In the part of channel coding, turbo trellis-coded modulation is considered. Encoded signals are transmitted in wireless fading channel; we employ turbo equalization, which consists of trellis equalizer and decoder in the receiver. The form of equalizer is not the same as the form of decoder. Because the forms of exchange of extrinsic information for equalizer and decoder in different forms, we have to use some methods to help transfer the extrinsic information as each other’s soft-input information. Because the computation load of equalizer is high, we also try to use T-BCJR algorithm to reduce the computation complexity of equalizer.

Contents
Introduction………………………………………………….1

1 Background and Related Works......................1

2 Motive of the Thesis............................2

3 Architecture of the Thesis......................3

Review of Previous Works...........................5

1 Trellis-coded modulation........................5

1.1 Set Partition.............................5

1.2 Trellis-coded Modulation Encoder..........7

2 Turbo code......................................8

3 Wireless Channel Model.........................12

3.1 Multi-path Fading Channel.................13

3.2 Rayleigh Distribution.....................14

4 BCJR Algorithm.................................16

Joint Turbo TCM and Equalizer.....................21

1 Turbo Trellis-Coded Modulation.................21

1.1 The Encoder Structure....................21

1.2 Systematic and Parity Component..........23

2 Proposed System Structure........................26

3 Combination of TTCM and Turbo Equalization.....29

4 The Extrinsic information from Equalizer to TTCM
Decoder..............................................31

4.1 Extrinsic- Weighted Delta................31

4.2 Softly Detected Vector.................34

5 T-BCJR Algorithm.................................37
6 The Extrinsic Information from TTCM Decoder to

  Equalizer.........................................39

6.1 TCM Trellis Probability Diagram..........39
6.2 The Extrinsic Information to Turbo Equalizer............................................42

Experiments and Discussions.......................45

1 Joint TTCM Decoders and Equalization in Rayleigh Selective Fading Channel.............................45

2 Effects of Channel Information Inaccuracy in ISI Fading Channel.......................................50

3 T-BCJR Algorithm............................................53


Conclusions........................................57

Bibliography.........................................59

List of Figures
1 Set partition for 8PSK..........................6
2 TCM encoder.....................................8
3 QPSK-to-8PSK mapping table......................8
4 Serial and parallel.............................9
5 Turbo code encoder.............................11
6 Turbo code decoder.............................11
7 Wireless environment...........................12
8 Time varying channel impulse response..........14
9 σ = Rayleigh distribution.....................15
10 BCJR trellis diagram...........................17
1 TTCM encoder...................................22
2 TTCM and turbo code decoders...................24
3 Complete TTCM decoder..........................25
4 Proposed system structure.....................26

5 Discrete-time equivalent channel..............27
6 System receiver structure.....................28
7 Turbo equalizer...............................30
8 TCM trellis diagram..........................32
9 Softly detected vector.......................36
10 Data allotment................................37
11 TCM trellis probability diagram...............40
12 Priori probability for time (k=2).................41
13 QPSK-to-8PSK probability transformer..............43
1 BER for TTCM in AWGN channel.......................46
2 BER for TTCM in Rayleigh (with extrinsic- weighted delta).................................................47
3 BER for TTCM in Rayleigh (with softly detected vector)................................................48
4 Compare Extrinsic- weighted delta with softly detected vector.................................................48
5 BER for ISI fading channel softly detected vector.................................................51
6 BER for ISI fading channel inaccuracy softly detected vector.................................................51
7 Compare ISI fading channel (with channel information inaccuracy)............................................53
8 BER for Rayleigh fading channel extrinsic- weighted delta (with T-BCJR)....................................54
9 BER for Rayleigh fading channel softly detected vector (with T-BCJR)..........................................55
10 BER for ISI Fading Channel Softly Detected Vector (with T-BCJR)..........................................55
11 BER for ISI fading channel inaccuracy fading softly detected vector (with T-BCJR)..........................56
Acronyms
TCM: turbo trellis modulation.
ISI: inter-symbol interfere.
TTCM: turbo trellis coded modulation.
T-BCJR: threshold BCJR
PCCC: parallel concatenated convolution codes.
SCCC: serial concatenated convolution codes.
HCCC: serial concatenated convolution codes.
MAP: Maximum a posteriori.
APP: a posteriori probability.
SISO: soft-input and soft-output.
TCQ: trellis coded quantization.

                                

Bibliography

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