隨著智慧型手機與平板電腦的普及，行動網路用戶的數量有了大幅成長，長程演進技術 (Long Term Evolution, LTE)的發展，就是為了滿足日益增加的網路流量需求，而語音通話的使用者依舊是佔有相當大的比例，因此，如何滿足LTE系統中的語音通話使用者便成為重要的議題。 在核心網路為全IP架構的LTE系統中，則是使用VoIP (Voice over Internet Protocol)技術來實現語音串流通話的傳送。VoIP封包對於延遲時間以及遺失率都有相當嚴格的要求，系統在控制通道有限以及通道品質不斷變化的情況下，對於VoIP封包的排程演算法便顯得非常重要，而動態排程演算法、持續性排程演算法以及半持續性排程演算法為常見的VoIP封包排程演算法。 本文將提出一個新的排程演算法，是基於半持續性排程演算法並加入動態排程的特性，使基地台能夠隨著環境改變而作出適當的資源分配。根據模擬結果所示，本文提出的排程演算法不僅可以降低VoIP封包的延遲時間以及遺失率，進而提升LTE系統對語音串流使用者的容量。 Long Term Evolution (LTE) is the key technology to deal with the increasing number of mobile network users. The core network of LTE system is all-IP based. In order to support voice service in LTE systems, VoIP (Voice over Internet Protocol) technology is used. The challenges of supporting VoIP transmission in LTE system are that the VoIP packet is loss sensitive and delay sensitive. The VoIP capacity is limited by control channel numbers. According to the challenges mentioned above, scheduling algorithm is main factor of reducing the delay time and packet loss rate. In this paper we propose a scheduling algorithm which is combining the semi-persistent scheduling algorithm and the dynamic scheduling algorithm. Due to the dynamic character, the scheduling pattern of VoIP user is more fit in with the channel condition. According to the simulation result, the proposed algorithm can effectively reduce the delay time and packet loss rate, while enhancing the VoIP capacity of LTE systems.
