有鑑於行動裝置(Moblie Station；MS)處於高速移動狀態下，例如高速鐵路環境，行動裝置與 基站(Base Station；BS)之間的空氣介面之訊號傳輸不穩定。為了縮短行動裝置的換手延遲時間， 本論文著手於改善後端核心網路通訊的延遲時間，藉以降低核心網路所需之Handover Preparation Time和縮短行動裝置的Interruption Time，避免封包遺失、封包多次重傳和Throughput的下降。本論 文係基於4G無線寬頻通訊技術，提出改良核心網路功能的方法。新增Preparation Zone Controller (P-Zone Controller；P.C)、Message Generator(M.G)、Message Interceptor(M.I)、Message Eliminator(M.E) 和Context Recorder(C.R)五種功能，透過空氣介面協助後端核心網路控制訊息的交換流程。除此之 外，本論文提出HO P-Zone(Handover Preparation Zone)概念，利用P.C判斷行動裝置的移動速度，根 據移動速度的快慢形成不同大小的P-Zone區域，並分別對於P-Zone區域內的基站建立資料路徑， 之後當行動裝置要與P-Zone區域內的基站建立連線時，可以省去建立資料路徑所需的時間。本論 文係基於802.16e標準及LTE的換手程序，提出P-Zone Initial Phase、P-Zone Execution Phase及P-Zone Advancing Phase三階段，以建構與更新P-Zone區域。除了降低換手延遲時間外，本論文亦提出有 效測量行動裝置移動速度的方法，並減少乒乓效應所產生的延遲時間。

When the mobile station (MS) is in high mobility state, the air signalling between base station (BS) and MS is not stable. For decreasing the handover latency of MS, this study focuses on shorten the core network communication delay to reduce the handover preparation time in core network and interruption time in MS. It avoided the packet loss, packet retransmission and throughput decreasing. This paper is based on 4G broadband wireless communication technology, and proposes the improving method for core network. We present the five functions to aid core network to exchange messages, including Preparation Zone Controller (P-Zone Controller; P.C), Message Generator (M.G), Message Interceptor (M.I), Message Eliminator (M.E) and Context Recorder (C.R). Furthermore, this research proposed the concept of handover preparation zone (HO P-Zone). Using P.C to detect speed of MS, we create the different P-Zone areas and establish data path for P-Zones. As the MS tries to connect to P-Zone, it has speed up the connection procedure.