毫米波頻段擁有大量的可用頻譜，也已經使用在IEEE 802.11ad的標準中，有望滿足無線擴增實境 (簡寫：AR)/虛擬實境 (簡寫：VR)應用的高吞吐量以及低延遲需求。儘管擁有這些優點，但因為毫米波處在高頻的關係，信號在如此高的頻率下路徑損耗也會劇烈增加，難以提供可靠的傳輸服務。雖然現在毫米波擁有波束成型技術來解決高頻環境下高路徑損耗的問題，但因為毫米波波束高度定向性的特性，使得毫米波信號容易受到各種障礙物(例如人、牆壁等)的影響，而造成無線通道的品質劇烈波盪，信號衰減。雖然基於雙連線下毫米波無線通道傳輸被認為是可以有效增加端到端吞吐量並且有效克服無線通道品質波動的有效方案，但在整體效能上還是不夠良好。

因此本文建立在單位時間下，僅一位使用者透過下行資料來進行固定位元速率(簡寫：CBR)流量的AR/VR應用，並且毫米波接取點到使用者的通道頻寬會小於AR/VR應用到毫米波接取點的通道頻寬，而網路閘道器到兩台毫米波無線接取點之間的通道頻寬分別要大於CBR流量的資料傳輸速率。我們提出了一個基於網路編碼之雙連線毫米波傳輸方法(mDUNO)。在mDUNO中，透過結合七個機制，分別為雙連線機制、優先權網路編碼機制、緩衝區管理機制、生成冗餘封包機制、調整標頭機制、關閉分散式協調功能重傳機制以及優先權解碼機制，來維持端到端的吞吐量以及延遲。mDUNO讓網路閘道器執行優先權網路編碼機制，並且同時透過網路編碼引入冗餘封包機制。目的是為了自適應性的利用多餘可用頻寬進行封包傳輸。另外，如果頻寬品質不好，則會透過緩衝區管理機制動態的剔除封包。同時，因為在本文環境中，不會存在隱藏節點的條件，因此為了省卻分散式協調的重傳開銷，我們將此重傳機制關閉。最後，mDUNO透過基於優先權的解碼機制來減少延遲。為了評估mDUNO的性能，我們將mDUNO實現在NS-3模擬器上，並且使用WiGig模組來實驗及模擬。實驗結果表明，mDUNO顯著的提高傳輸性能，維持良好的端到端吞吐量以及低延遲的傳輸表現。

The millimeter-wave (mmWave) frequency band has a vast available spectrum that has been utilized in the IEEE 802.11ad standard. mmWave has the potential to satisfy the demand of numerous wireless AR/VR applications with high-throughput and low-latency. Despite this advantage, the signal suffers from higher path loss. This reason makes mmWave hard to provide reliable transmission service. Although mmWave has beamforming techniques to overcome high path loss. By highly directional characteristics of the mmWave beams, mmWave is vulnerable blocked by various obstacles, such as walls or humans. These obstructions make wireless channel fluctuate dynamically and signals attenuation increase rapidly. Dual-connectivity based mmWave wireless link transmission not only improves end-to-end throughput but also overcomes the effect of channel fluctuant. However, the overall performance of transmission is still underperformed.

In this thesis, we propose a network coding based mmWave dual-link transmission scheme (mDUNO) for a user to perform a constant bit rate (CBR) AR/VR service. Moreover, the bandwidth from the mmWave access point to the user will be less than the bandwidth between the AR/VR application and the mmWave access point, and the bandwidth from the gateway to two mmWave wireless access points is respectively greater than the data rate of the CBR traffic. In the mDUNO scheme, mDUNO consists of seven strategies, dual connectivity, priority-based network coding strategy, generating redundancy packet strategy, buffer management strategy, adjusting packet header strategy, closing Distributed Coordination Function (DCF) retransmission strategy and priority-based decoding strategy. At first, network gateway will execute the priority-based network coding strategy before forwarding the packets. Furthermore, gateway will generate redundancy packets through network coding
. These aims to achieve adaptively utilizing spare bandwidth to forward the packets. Additionally, mDUNO actively erasures packets via the buffer management strategy. To save the retransmission overhead of DCF, we also disable the DCF retransmission in mDUNO. In the end, mDUNO reduces the decoding latency via priority-based decoding strategy. To evaluate the performance of the mDUNO scheme, we implement mDUNO on NS-3 and also conduct the experiments using the WiGig module. The results show that mDUNO not only significantly improves the transmission performance but also provides excellent end-to-end throughput and low-latency.

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