由於下世代行動通訊的到來以及未來數據流量激增的挑戰，第三代合作夥伴計劃將裝置對裝置 (device-to-device; D2D) 通訊納入了長期演進技術升級版的重點技術中，而為了解決通道品質不佳之裝置傳輸速率的問題，在之後又提出一種中繼模式的 D2D 通訊。
在 D2D 中繼的技術中，通道品質不佳的裝置可藉由鄰近通道品質較佳的用戶協助轉傳，並透過頻段的重複使用，來改善裝置的傳輸速率以及提升整體系統傳輸量。然而目前相關的 D2D 中繼研究大多假設一般用戶願意協助轉傳，但現實情況提供協助的用戶在幫忙轉傳資料時，勢必會消耗自身額外的電量，在付出與收穫的原則下，若是沒有給予適當的回饋，用戶協助意願可能不高，因此如何提升用戶協助的意願是個重要的課題。
本論文以達到營運商與用戶間雙贏的局面為目標，在 D2D 中繼模式下以公平比例排程法為基礎提出了一種基於令牌 (Token) 的回饋機制 (Token-Based Reward Proportional Fair; TBRPF)，此演算法基地台會給予成功協助的用戶 Token，用戶之後可利用所獲得的 Token 搭配重新調整優先權之方法來提升競爭資源時的優先權。模擬結果顯示，本論文所提出的 TBRPF 機制與未使用 D2D 中繼技術之機制相比，不但能在系統傳輸量上有優異的表現，也因為本論文的 Token 回饋機制使得用戶封包丟棄率得以降低，尤其在所需協助的裝置增加或是縮短裝置回報週期時，更能凸顯出本論文機制的優勢。

Because of the availability of the next generation mobile communication, and the sharp increase in traffic flow, device-to-device (D2D) communication is included as a part of important technology in Long Term Evolution Advanced by 3rd Generation Partnership Project (3GPP). In order to solve the problem of devices which have poor channel condition, 3GPP proposed a kind of relaying mode in D2D communication.
In D2D relay, devices with poor channel condition can improve transmission rate and overall system throughput by relying on nearby user equipment (UE) to assist in transmission and by reusing spectrum. The researches regarding D2D relay usually assume that most of the UEs are willing to provide assistance, however, in reality, relaying data could lead to extra power consumption. Under the principle of balancing pay and gain, UEs’ relaying incentive would be reduced if no proper reward is provided. Therefore, how to improve UE’s willingness of relaying is a significant concern.
With the intention of realizing win-win between network operator and UEs, this article proposed a Token-Based Reward Proportional Fair (TBRPF) based on proportional fair (PF). The base station of this algorithm will provide a Token to the UE who has successfully assisted in transmission, then the UE can use this Token along with the method of adjusting priorities to upgrade its priority in resource allocation. According to simulation results, in comparison with the mechanism without D2D relay, TBRPF not only has excellent performance in throughput, but also reduces UE drop ratio as a result of rewarding mechanism proposed in this article. The advantage of the mechanism become noticeable especially when devices need assistance increased or report period was shortened.

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