這份論文研究了兩種速龍編碼的無線通訊系統：使用者多工系統和合作式通訊系統。

首先是上行鍊路環境中的速龍編碼使用者多工系統。與傳統的功域非正交多工系統相比，論文中提出的系統不需要使用連續消除技術來進行訊號偵測。另外，提出的系統提升了使用者的傳輸速率和降低所需的overhead。接著，論文詳述了估測傳輸速率的方法和系統性能比較。更進一步，為了提升錯誤率性能，論文提出了一個兩階段維度分佈搜尋演算法。從模擬結果得知，提出的速龍編碼使用者多工系統在不同的使用者位置環境中，在性能上可勝過傳統的功域非正交多工系統。另外的是，提出的兩階段維度分佈搜尋演算法可進一步的提升性能，並且接近預測結果。

再來是下行鍊路環境中的速龍編碼非同調分散式么正空時調變系統，在這系統中考慮了放大前送和解碼前送的中繼協議並且使用無線中繼網絡通道模型。在論文該部分中首先詳述了放大前送和解碼前送中繼協議的傳送接收方法，並且使用速龍編碼與分散式么正空時調變系統，同時，也研究了非同調解調器。接著，論文提出了分散式么正空時調變的星座點搜尋法和維度分佈搜尋演算法來提升系統性能。從模擬結果得知，提出的非同調系統吞吐量可以勝過其他研究中提出的非同調分散式多天線系統。

在論文的最後一部份提出了一個新穎的分散式訊號結構，稱之為非正交空時調變系統。藉由該非正交空時調變訊號結構可提升前述非同調分散式么正空時調變系統的吞吐量。在論文該部分中首先提出了由么正空時調變與空間多工調變訊號結合而成的分散式訊號結構。接著，論文研究了與之配合速龍編碼系統的傳送接收方法。從性能評估中可以發現，前述非同調分散式么正空時調變系統的吞吐量可以藉由新提出的非正交分散式訊號結構有效率的提升，尤其是當中繼節點離訊源節點較遠的狀況下，可以得到更下顯著的結果。

This dissertation describes a study of two Raptor coded wireless communication schemes, namely the user multiplexing scheme and the cooperative communication scheme.

First, the Raptor-coded user multiplexing scheme for a downlink scenario was investigated. Compared to the power-domain non-orthogonal multiple access (NOMA) scheme, the proposed scheme does not require the inclusion of the successive interference (SIC) cancellation technique for signal detection. In addition, the proposed scheme enhances user transmission rates and reduces the overhead required for reliable transmissions. Next, an estimation of the transmission rates for the scheme was performed and the performance was compared for both the proposed scheme and the power-domain NOMA scheme. Further, to improve the error performance, a two-step degree distribution search process was also proposed. From the simulation results, it is shown that the proposed scheme outperforms the Raptor coded power-domain NOMA scheme in several user pair locations, and the degree distribution search process improves the performance, approaching the predicted limits.

Next, an investigation was conducted into Raptor-coded noncoherent distributed unitary space-time modulation (USTM) schemes for an uplink scenario, where both the amplify-and-forward (AF) and decode-and-forward (DF) relaying protocols are considered, based on a wireless relay network with arbitrary path gains for the channel fading coefficients. First, the AF and DF relaying procedures were investigated based on the use of an inner USTM signal and an outer Raptor code, and the related non-coherent detectors were also derived. Second, the constellation search for the distributed USTM signal, as well as the optimization of the Raptor code, were investigated in order to enhance the system performance. From the simulation results, it is shown that the throughput performance for the designed systems effectively approach the predicted limit, and outperform the noncoherent distributed MIMO scheme reported in the previous literature.

In the last part of the dissertation, a novel distributed signal structure, known as non-orthogonal space-time modulation (NOSTM), was proposed in order to improve the throughput performance for the distributed USTM scheme. First, the distributed NOSTM signal was proposed based on a combination of USTM and spatial multiplexing (SM). Then, a Raptor-coded distributed scheme was constructed for the relay network, and the corresponding transmission and reception procedures were also investigated. From the performance evaluations, it can be shown that the throughput performance can be effectively improved, especially for cases where the location of the chosen relay nodes is distant from the source node.

1 Introduction 1
2 Preliminary 5
2.1 Raptor code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1.1 Decoding algorithm: belief propagation (BP) . . . . . . . 6
2.1.2 Obtaining a degree distribution for the Raptor code . . . 7
2.2 The next generation mobile communication standards . . . . . . 11
2.2.1 The NOMA scheme: power-domain NOMA . . . . . . . 12
2.3 Distributed systems . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.3.1 Unitary space-time coding/modulation (USTM) . . . . . 18
2.3.2 Noncoherent Receiver . . . . . . . . . . . . . . . . . . . . 19
2.3.3 Distributed USTM (DUSTM) . . . . . . . . . . . . . . . 22
3 A Downlink Multiplexing Scheme Using Physical-layer Raptor Coding 26
3.1 Preliminary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.1.1 Downlink BC model . . . . . . . . . . . . . . . . . . . . 27
3.1.2 The PD-NOMA scheme . . . . . . . . . . . . . . . . . . 28
3.2 The proposed NOMA-PRC scheme . . . . . . . . . . . . . . . . 30
3.2.1 System description . . . . . . . . . . . . . . . . . . . . . 30
3.2.2 Transmission rate investigation . . . . . . . . . . . . . . 33
3.2.3 Overhead and BER performance evaluation . . . . . . . 39
3.3 Code search process for the NOMA-PRC scheme . . . . . . . . . 50
3.3.1 MI formulas . . . . . . . . . . . . . . . . . . . . . . . . . 50
3.3.2 Iterative search process . . . . . . . . . . . . . . . . . . . 52
3.3.3 Search results . . . . . . . . . . . . . . . . . . . . . . . . 58
3.4 Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
4 Raptor-coded non-coherent cooperative schemes 64
4.1 The considered model of the wireless relay network . . . . . . . 65
4.2 Two proposed distributed USTM schemes . . . . . . . . . . . . 66
4.2.1 AF relaying scenario: distributed USTM signal transmission process . . . . . . . . . . . . . . . . . . . . . . . 66
4.2.2 AF relaying scenario: distributed USTM signal reception process . . . . . . . . . . . . . . . . . . . . . . . . . 68
4.2.3 DF relaying scenario: distributed USTM signal transmission and reception process . . . . . . . . . . . . . . . 72
4.2.4 Two relaying scenarios with a Raptor coding . . . . . . . 76
4.3 Performance evaluation for the AF and DF-based Raptor-coded distributed schemes . . . . . . . . . . . . . . . . . . . . . . . . . 80
4.3.1 Performance: the AF relaying scenario . . . . . . . . . . 81
4.3.2 Performance: the DF relaying scenario . . . . . . . . . . 83
4.4 System optimization for the proposed Raptor-coded distributed USTM scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
4.4.1 Design for the Distributed USTM Constellation . . . . . 85
4.4.2 Design for the LT Degree Distribution . . . . . . . . . . 87
4.5 Performance evaluation for the optimization procedure . . . . . 90
4.6 Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
5 A Raptor-coded Distributed Noncoherent Scheme Using Non-orthogonal Space-time Modulation 97
5.1 Raptor-Coded Distributed Noncoherent Schemes Using NOSTM Signal and Dynamic DF Relaying . . . . . . . . . . . . . . . . . 98
5.1.1 The Dynamic DF Relaying Protocol . . . . . . . . . . . 99
5.1.2 The proposed Distributed Noncoherent Non-orthogonal Space-time Modulation . . . . . . . . . . . . . . . . . . . 102
5.1.3 Noncoherent MAP detector for the distributed NOSTM signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
5.2 Performance Evaluation . . . . . . . . . . . . . . . . . . . . . . 106
5.3 Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
6 Conclusion 112

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