| Abstract: | 隨著行動裝置的蓬勃發展,行動裝置對於高速網路的品質要求也明顯地比以前高上許多。許多研究人員正盡全力地發展各種不同的通訊方法和通訊服務來服務使用者。同時,行動裝置熱門程度在最近幾年也飛快的成長。另一方面,從 2008 年 LTE 網路被發表以來,直到現在它都還是受到大家矚目。在 LTE 中,行動裝置 UE 從基地台 A 移動到基地台 B 時,LTE 需要協助它執行換手程序,俾讓 UE 順利地從基地台 A 換手到基地台 B,使得行動裝置能夠在保持連線的狀態下繼續移動。如果換手的工作沒有成功地完成,UE 必須重新連接到網路,使用者將會感覺到大量的通訊延遲。現階段決定是否換手仍然還是以無線電波之強弱為主要的參考依據。不過仍然會存在許多問題。這是因為無線電波的特性使然,舉凡行動裝置的位置、移動速度、移動方向都很有可能影響電波的強度。因而在這篇研究當中,我們使用了 GPS 系統來輔助 LTE 之換手機制,並以UE 當前之狀態,如:移動方向、移動速度、信號強度、距離等因素來決定欲換手的對象,使得UE 能夠更精準的找到最合適的換手對象,進而提昇 LTE 整體的運作效率。
With the rising popularity of mobile networks, the requirements of accessing wireless servicesthrough mobile devices have been significantly higher than before. Many researches have developeddifferent communication functions and applications to serve users. The population of mobile usersincreases significantly in recent years. Also, since 2008 Long Term Evolution (LTE for short) hasattracted researchers’ attention. When a user equipment (UE for short) moves from an evolvedNode B (eNB for short) to another, the LTE needs to help the UE to hand over from the servingeNB(SeNB for short)and target eNB(TeNB for short) by managing the provided resources so that theconnection between the UE and the SeNB(TeNB) can be well maintained. If handover is incompletelyperformed, the UE may need to re-enter the network. If it is true, then users will experience a longercommunication delay. In face, the connection may also be disconnected. Currently, the radio issue isstill considered as the key factor that affects the time consumed by the handover procedure. However,it is insufficient if we only measure the strength of the radio that the UE receives from its SeNBto determine whether UE needs to hand over or not since the UE’s location, moving speed andmoving direction are also important factors that may affect the handover quality. In this study, weemploy the information provided by a GPS and use several status parameters, e.g, UE’s location,moving speed, moving direction and distance to help the determination of TeNB for LTE systemsduring handover so as to more accurately choose the most suitable TeNB and improve handoverperformance. |
