應用於裝置對裝置通訊的機會式中繼網路資源分配方案

Abstract

在本篇論文當中，我們提出了一套應用於裝置對裝置通訊的網路資源分配方案。除了考量直接的裝置對裝置的傳輸外，我們將機會式中繼裝置轉傳的傳輸模式納入考量。每個裝置對裝置的通訊可以藉由一個適當的中繼裝置轉傳資料來提升系統的吞吐量。此外，我們將一個多頻帶細胞網路下的資源分配問題拆解成三個部分，分別是中繼裝置選擇、頻帶配置及傳輸能量調整，並適當地對於每個部分做出有效的資源分配。在第一部分，我們將問題轉換成一個最大權重二分匹配問題。此外，我們也提出一個前置過濾演算法來降低使用匈牙利演算法來解最大權重二分匹配問題時的計算複雜度。在第二部分，我們使用圖學著色演算法分配頻寬資源。在第三部分，我們提出一個可適時降低中繼裝置傳輸能量的方法。從模擬結果當中可以發現我們提出的機會式中繼裝置轉傳的傳輸模式可以有效的提升系統的吞吐量。

In this thesis, we propose a scalable interference-aware channel allocation mechanism to enhance the system capacity by mitigating the interference between Device-to-Device(D2D) connections in a multi-channel cellular system. Instead of using a direct single-hop transmission only, we propose an opportunistic two-hop D2D transmission scheme which allows using a suitable relay device. The problem of maximizing the system throughput can be formulated as a mixed integer-linear programming problem, which is NP-hard. To reduce the computational complexity, we propose solving the problem in three phases, that are responsible for relay selection, channel assignment and power control, respectively. In the first phase, we transform the problem of relay selection into a weighted matching problem. We propose using pre-filtering to reduce the complexity when the Hungarian algorithm is used to solve the weighted matching problem. In the second phase, we apply graph coloring algorithm to attack the problem of channel assignment. In the third phase, we propose an effective approach to control the transmission power and reduce the energy consumption at relays. The simulation results show that the proposed opportunistic two-hop D2D relay mechanism could significantly outperform the direct transmission only strategy, especially when D2D transmission distance increases.