隨著各式行動通訊裝置與應用的技術發展，高速率和低延遲傳輸支援為下世代無線通訊系統一重要設計考量。本論文提出在全雙工中繼網路下，基於類比網路編碼之動態調變(Analog Network Coding assisted Adaptive Modulation, ANCAM)機制以縮短封包傳輸時間並提高網路效能。ANCAM藉由類比網路編碼之訊號加成特性，改善全雙工環境下自我干擾對系統上的影響，並透過類比網路編碼進一步減少封包傳輸的時間。此外，並藉著自我偵測通道環境動態更改調變機制能有效提升系統吞吐量。 本論文使用不會對所傳輸的資料進行額外處理，僅單純將資料放大並傳輸給接收端之放大轉發(Amplify-and-forward)全雙工(Full Duplex)中繼器，不僅可大幅縮短傳輸時間，並減少中繼器的工作量。然而，全雙工傳輸將使接收端收到傳輸端的訊號夾雜著自己所傳輸的訊號，亦即中繼器在全雙工模式傳輸下造成的自我干擾，使得接收端訊號解調困難，並恐減少預期效益。另一方面，類比網路編碼能運用放大轉發中繼器單純放大傳出的特性，將兩兩發送接收端的訊號進行結合同時回傳，進一步減少傳輸時間，但接收端需要額外處理訊號的還原以維持傳輸效能。為了有效運用全雙工與類比網路編碼降低傳輸時間特性並且改善各自帶來的系統效能降低問題，我們設計的ANCAM機制在傳輸的封包前端和後端加入設計過的pilot sequence 偵測訊號是否為干擾，並且將干擾進而消除。另外，我們亦設計reference sequence協助估測目前環境的狀況動態改變調變機制，使得ANCAM應用於動態網路環境中仍能增加系統的吞吐量和減少解調的錯誤。根據模擬的結果，ANCAM在全雙工中繼網路環境下與既有機制相比，既能有效縮短傳輸時間，並且大幅提高系統效能。 ;With the development of modern technologies, high-rate and low-latency transmission becomes important considerations for next-generation wireless communication systems design aiming to support various mobile communication devices and applications. In this thesis, we propose an Analog Network Coding assisted Adaptive Modulation (ANCAM) mechanism to improve network performance in terms of packet transmission time and throughput under full duplex relays formed wireless network. ANCAM not only improves the effect of self-interference suppression in full duplex relay system but also further reduces packet transmission time by exploiting the characteristics of signal-addition via analog network coding. In addition, ANCAM equips with a self-channel detection scheme to actively adjust modulation scheme in react to the channel status so that the system throughput is efficiently enhanced. To reduce the transmission time, this thesis considers an Amplify-and-Forward Full Duplex relay which simply amplifies and forwards data without additional process. In this way, the relay workload is also reduced. However, full duplex transmission will cause self-interference since its own transmission signal power is larger than the received signal, and thus the receiver might obtain higher bit error rate and lower system performance. Moreover, analog network coding utilizes the characteristics of the amplify-and-forward relay by simply combining the two simultaneously received signals before sends it to the corresponding destinations. Under this condition, receivers need additional process to recover the encoded signal as well as maintain the transmission performance. To overcome the mentioned problem and improve system performance, we propose an ANCAM mechanism by introducing a designed pilot sequence to the transmitted packet to assist signal process during transmission. Furthermore, a reference sequence is also designed to estimate channel condition for modulation scheme adjustment to react to the dynamic change of network environment. Simulation results show that with full duplex relay, ANCAM can effectively shorten the transmission time and greatly improve the system performance compared with existing mechanisms.
