長期演進網路中基於鄰近搜尋之直接通訊模式選擇方法

Abstract

裝置對裝置直接通訊(D2D)於生活中有許多可應用的領域，例如：機器對機器直接通訊、中繼資料傳輸、分散網路系統負載、與鄰近玩家連線進行遊戲對戰…等等。傳統的蜂巢式網路系統中，欲建立兩個行動裝置間之連結，必須經由基地台與核心網路，而在蜂巢式網路底下加入D2D通訊方法，可以降低基地台與核心網路的負載，並可縮短資料傳輸路徑，藉由D2D通訊除了可降低通訊裝置的耗電量外，亦可增強頻譜使用效率和提升整個網路系統的吞吐量。若欲讓蜂巢式網路底下加入D2D通訊的優勢有明顯的效益表現，組成一個D2D群的演算法與合適的模式選擇機制會是相當重要且值得探討的議題。 本論文中，我們在LTE蜂巢式網路使用D2D通訊的環境下，基於鄰近搜尋之原則，設計一個行動裝置選擇模式的方法，我們提出了三種可供選擇的模式：蜂巢式網路模式、D2D模式與資料中繼模式，並由行動裝置本身發起鄰近搜尋，再根據獲得的數據判斷該選擇何種模式進行資料傳輸。藉由MATLAB進行實驗模擬，結果證明我們提出的方法除了能達到提升系統流通量的目的外，亦能降低使用D2D通訊對原本蜂巢式網路用戶所產生的影響。

Device-to-Device (D2D) communication in cellular network is defined as direct communication between mobile users without traversing the eNB or core network. In underlay D2D communication, cellular and D2D communications share the same radio resources. D2D communication in cellular network was initially proposed to enhance network performance. There has many use-cases of D2D communication in cellular networks such as Machine-to-Machine communication, relaying, cellular offloading, content distribution, and gaming. By using D2D communication in cellular networks, cellular network can benefit from the advantages of D2D communication such as enhancing spectrum efficiency and mobile devices can reducing transmission power. Most of the spectrum efficiency improvement can be achieved by employing a suitable D2D grouping algorithm and appropriate mode selection scheme. In this thesis, we propose a mode selection scheme with three mode: Cellular Mode, D2D Mode and Relay Mode. We organize the D2D pair by launching proximity discovery and UEs take all decisions about D2D grouping. This method can reduce eNB’s burden of controlling whole network system and will not cause heavy computation to UEs. By applying three modes in the network system, it can minimize the drawback of using D2D communication underlay LTE cellular network and maximize the spectrum efficiency and system throughput. We simulate our proposed scheme by using MATLAB simulator. The result shows that our method can not only upgrade the system throughput but also degrade the influence caused by adding D2D communication into LTE cellular network of cellular users.