D2D通訊之分散式公平隨機存取設計

Abstract

為了解決近年來持續增加的行動網路資料流量，D2D通訊成為一個受到矚目的紓解負載技術。D2D通訊技術藉由不透過基地台傳輸資料，改由裝置間直接的溝通縮短通訊延遲並且大幅提升網路容量增益。然而，在沒有使用特定避干擾機制下，不同D2D通訊之間都會產生嚴重的干擾。因此，如何去協調和分配無線資源就顯得更為重要。 在此篇論文中，我們提出一個名為公平分散式隨機存取機制(FDRAS)，此機制可以有效實現在使用多載波傳輸技術的D2D通訊上。相較於集中式的資源分配機制，FDRAS具有不會浪費太多資源在機制本身且對於資料流的變化更能即時反應的優點。除此之外，我們提出的隨機存取機制還可以更彈性的依據不同的D2D傳送端所請求的資源多寡作無線資源的分配。本論文最後藉由模擬，成功驗證所提出的公平分散式隨機存取機制可以使裝置間有效的避免碰撞且在不同的環境下保持穩定的表現。

To cope with increasing mobile data traffic in recent years, Device-to-Device (D2D) communication has attracted much attention and be a solution. D2D communication can provide shorter delay and a significant capacity gain by direct communication between devices without a base station. However, every D2D pair can generate serious interference to other D2D links without any proper interference control mechanism. Therefore, how to coordinate and allocate radio resource is obviously important. In this thesis, we propose a contention based and fair distributed random access scheme(FDRAS). This scheme can be effectively applied to D2D communication based on multi-carrier communication systems (e.g., OFDMA). Compared to centralized resource allocation scheme, FDRAS is advantageous in that it has smaller control overhead and is more responsive to traffic demands. In addition, our proposed scheme is more feasible by allocating radio resource according to different transmitters’ requests. By simulation, we show that the proposed scheme, FDRAS, enables devices to effectively avoid collisions and maintains stable performance in different scenarios.