6 1 Original Base Station Handoff Base Station
圖 6. 1:交遞 Original Base Station Handoff Base Station 3
交遞偵測策略 z手機掌控交遞 (Mobile Controlled Handoff, MCHO) y使用於 DECT 與 PACS 等低階 TDMA 系統 z網路掌控交遞 (Network Controlled Handoff, NCHO) y使用於 CT-2 Plus 與 AMPS 等以 FDMA 為主的 類比式蜂巢式系統 z手機輔助交遞 (Mobile Assisted Handoff, MAHO) y使用於 GSM 等高階蜂巢式系統 11
圖 6. 2:手機品質維護程序 步驟一: Measurement Process Yes 步驟二: Is Link Quality Acceptable? 步驟三: No Select New Channel or Time Slot 步驟四: Execute ALT or TST 15
z初始通話要求 (Initial Access Request) y塞機 (Blocked Call) z交遞要求 (Handoff Request) y被迫中斷 (Forced Termination) z交遞-初始存取通道給定計策 y無優先計策 (Non-Prioritized Scheme, NPS) y保留通道計策 (Reserved Channel Scheme, RCS) y排隊優先計策 (Queueing Priority Scheme, QPS) y通道分割計策 (Sub-Rating Scheme, SRS) 20
z通道給定程序 y動態式通道給定 (Dynamic Channel Assignment, DCA) y固定式通道給定 (Fixed Channel Assignment, FCA) y半固定式自動頻率給定 (Quasi-Static Autonomous Frequency Assignment, QSAFA) y其他固定型、動態型或彈性型程序 21
圖 6. 3:無優先計策之流程圖 New or handoff call arrival Channel available ? no Call blocked yes Channel assigned Ongoing call Channel released 23
圖 6. 4:保留通道計策之流程圖 New call arrival no Normal channel available? Call blocked yes Channel assigned Handoff call arrival Normal channel available ? yes Channel assigned Ongoing call no Reserved channel available ? yes Ongoing call Channel released no Channel released Call blocked 25
排隊優先計策 (QPS) z在互相覆蓋區域中讓手機的通話可由相鄰 細胞的任一基地台處理 y交遞區域 (handoff area) y惡化區間 (degradation interval) y等候佇列 (waiting queue) x先進先出計策 (First-In-First-Out (FIFO) Scheme) x量測型優先計策 (Measured-Based Priority Scheme, MBPS) z圖 6. 5 26
圖 6. 5:排隊優先計策之流程圖 Handoff call arrival Normal channel available ? no Insert the call into the waiting queue yes no Call no blocked A yes channel is available before the call expires? Channel assigned Ongoing call New call channel released Channel released Is the waiting queue empty? yes The channel is idle 27
圖 6. 6:通道分割計策之流程圖 Handoff call arrival Call no blocked Each channel of the subrated pair is upgraded to full-rate channel Channel available ? no Channel available for sub-rating? yes Is there any sub-rated channel yes pair? no The channel is idle Channel assigned Ongoing call New call channel released Channel released Is no the released channel sub-rated? yes The other channel of the 29 sub-rated pair is upgraded
PACS 架構 z圖 6. 8 y無線電基地台 (Radio Port, RP) y無線電基地台控制單元 (Radio Port Control Unit, RPCU) y交換機 (Switch) y擷取管理器 (Access Manager, AM) 37
圖 6. 8:PACS架構 38
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