最近，多接入邊緣計算（MEC）和裝置對裝置（D2D）通信已經成為減輕行動網路上因多媒體串流服務造成的爆炸性數據流量的重要技術。ETSI MEC引入了一個部署在基站旁邊的MEC伺服器，以MEC應用程序（MEC Apps）的形式在網路邊緣提供IT服務環境和雲端計算功能。D2D通信允許行動裝置以低延遲和高頻寬執行直接通信和數據交換，而無需任何基礎設施。我們設想一種架構，其中MEC和D2D協同合作並實現階層式的流量卸載。我們設計並實現了MEC輔助的D2D直播服務，該服務可以將串流內容緩存在MEC服務器中並在不訪問互聯網的情況下傳輸給使用者，並且可以使用D2D通信直接在裝置之間共享串流內容。我們的實作包括MEC App和User App。 MEC App實現了兩個主要功能：裝置管理和串流緩存。除了一般的多媒體串流功能外，我們的User App還提供D2D網絡組成和D2D串流共享的功能。本文進一步開發了一種基於D2D網路的自適性串流位元率調變演算法，能夠選擇合適的視頻質量等級進行請求。實驗結果證明我們提出的架構和位元率調變演算法可以為串流服務中的用戶提供更佳的QoE。

Recently, Multi-Access Edge Computing (MEC) and device-to-device (D2D) communication have become promising technologies to relieve the heavy traffic on the mobile network caused by the exploding demand for multi-media streaming services. ETSI MEC introduces an MEC server deployed beside base station that provides an IT service environment and cloud-computing capabilities at the edge of the network in the form of MEC applications (MEC Apps). D2D communication allows mobile devices to perform direct communication and data exchange with low latency and high bandwidth, without the need of any infrastructures. We envision an architecture where MEC and D2D work in collaboration to achieve traffic offloading in a hierarchical manner. We design and implement an MEC-assisted D2D live streaming service that can cache the stream content in the MEC server and stream to users without accessing the Internet, and can share the stream content between devices directly using D2D communication. The implementation including an MEC App and a User App. The MEC App implements two main functions: device management and content caching. Besides general functions of a streaming app, our User App provides capabilities of D2D network formation and D2D content sharing. This paper further develops a rate adaptation heuristic for adaptive streaming over D2D network, which is able to select a suitable video quality level to request. The experiment results justify that our proposed architecture and the rate adaptation heuristic can provide an improved QoE for users in mobile streaming service.

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