臺灣博碩士論文加值系統

在正交分頻多工系統中，位元翻轉技術可用來降低峰均比。
而錯誤更正編碼可用來減緩因位元翻轉技術所造成的位元錯誤率惡化。
我們提出一些設計去適當地整合特意位元翻轉技術跟非對稱錯誤保護的錯誤更正碼。
我們使用一種修改過的密度進化方法來尋找適合我們位元翻轉系統的編碼度分佈。
而另一種錯誤更正碼，即猛禽碼亦可被用來減輕因翻轉位元所造成的位元錯誤率惡化。
模擬結果顯示出在很多狀況當中，我們所提出的設計可以有效的降低峰均比而且伴隨著非常微弱的位元錯誤率惡化。

In the orthogonal frequency division multiplexing (OFDM) communications, bit flipping can be used for the reduction of peak-to-average-power ratio (PAPR).
Error-correction coding can be used to relieve the degradation of bit-error rates (BER) resultant from the bit-flipping.
We propose designs which appropriately integrate deliberate bit flipping and error-correcting codes with unequal error protection.
A modified density evolution method is used for obtaining appropriate code degree distributions to our bit-flipping system.
Another error-correcting codes, i.e. Raptor code also can be adopted to mitigate the BER degradation causing of the flipped bits.
Simulation results show that our proposed designs can obtain effective PAPR reduction with very minor BER degradation in many cases.

口試委員會審定書 i
致謝iii
中文摘要v
Abstract vii
Contents ix
List of Figures xi
List of Tables xv
1 Introduction 1
2 Deliberate Bit Flipping For PAPR Reduction 5
2.1 The Proposed System Model And Some Basics . . . . . . . . . . . . . 5
2.2 Deliberate Bit-Flipping For PAPR Reduction . . . . . . . . . . . . . . 10
2.2.1 Clipping-Based Bit-Flipping (CBBF) Method . . . . . . . . . . 13
2.2.2 Active Constellation Extension Combined With CBBF Method 17
2.2.3 SLM-Based Bit-Flipping (SLMBBF) Method . . . . . . . . . . 22
2.3 PAPR Performances . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.4 Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3 Error Correction Based On Unequal Error Protection For Bit-Flipping System
41
3.1 Unequal Error Protection . . . . . . . . . . . . . . . . . . . . . . . . . 42
3.2 Modified Density Evolution . . . . . . . . . . . . . . . . . . . . . . . 44
3.2.1 Quantized Density Evolution (QDE) . . . . . . . . . . . . . . . 44
3.2.2 Modified QDE for Systems with Flipped Bits . . . . . . . . . . 47
3.3 Code Search . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
3.4 Modification of Channel LLR . . . . . . . . . . . . . . . . . . . . . . 54
3.5 BER Peroformances . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
3.6 Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
4 Error Correction Based On Raptor Codes For Bit-Flipping System 71
4.1 Raptor Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
4.2 Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
4.3 Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
5 Conclusions and Future Work 85
Bibliography 89

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