在大型天然災害發生之後的黃金救援時期，災民存活率和救災效益之提昇極度仰賴於一個順暢的通訊系統。由歷年來大型災變的經驗中我們可知，行動通訊系統其實是不可靠且極為脆弱的，基地台之電力供應中斷或連接後端固定網路線路（Backhaul）之損毀都將使得通訊系統癱瘓而影響救災工作效率。
本研究提出一種新的應急通訊系統，利用原有行動通訊系統中未損毀但失去連網能力的基地台，藉由臨時供應的電力恢復其運轉，並以無線通訊設備與鄰近基地台互連建構一個臨時應急性的網路，稱為應急蜂巢式行動通訊網路（Contingency Cellular Network，CCN），供災區內手機用戶進行通訊。由於災區內部通訊的對象通常是一個特定的群組角色，而非一個特定人員，而災民與救災人員也不知彼此所在位置及聯絡的方式，因此無法以平常的撥號方式發起呼叫。本研究以CCN網路架構為基礎，設計並實作群組通訊模式，讓災區內人員以簡碼方式向任一群組發起呼叫並建立通話。
為驗證CCN群組通訊設計之可行性及效能，我們以IEEE802.11 Wi-Fi無線網路環境建置模擬系統，並以Android平台手機搭配VoIP軟體模擬手機與系統連線以進行通話。最後設計了一連串的實驗評估本模擬系統之效能。從實驗結果可知，本系統可於短時間內即時回應使用者註冊需求及完成通話連線處理；當通話數在30通以下時，Mouth-to-Ear Delay (MED) 值可維持在400ms以下，語音品質控制在一般VoIP使用者可容許的範圍之內。本實驗可作為未來改進系統功能和建置架構之參考依據。 / When stricken by a catastrophic natural disaster, the efficiency of disaster response operation is very critical to life saving. The efficiency of disaster response operation is greatly depending on communication systems. However, they were usually not dependable, including cellular networks, and often crashed due to power outage and backhaul link breakage. The failure of communication systems caused a big coordination problem to many disaster response operations.
This thesis proposes a Contingency Cellular Network (CCN) by connecting isolated base stations to survival base stations using long-range wireless links to restore part of cellular network functionality. People can use their own cell phones for emergency communication in the disaster areas. CCN will be able to support many disaster response workers in the early hours of catastrophic natural disasters, thus to save many lives.
Since the receiver of a phone call in a disaster area is usually a resource (agent), not a particular person, we designed a special Agency communication mode for CCN allowing CCN users to initiate a phone call to a nearby resource by dialing a designated agency number, instead of a real phone number. To verify our design, we implemented an emulated CCN system using an IEEE 802.11 Wireless LAN to mimic the CCN network and Android small phones with VoIP software to mimic user terminals.
Finally, we conducted a series of experiments to evaluate the performance of the emulated system. The experimental results show that the emulated system can respond promptly to the user registration and call set-up requests. Mouth-to-Ear Delay (MED) can be effectively controlled below 400 ms when there is no more than 30 calls originated. This system may be used as reference for the future development of contingency communication networks.
| Identifer | oai:union.ndltd.org:CHENGCHI/G0099971009 |
| Creators | 張惠晴, Chang, Hui Ching |
| Publisher | 國立政治大學 |
| Source Sets | National Chengchi University Libraries |
| Language | 中文 |
| Detected Language | English |
| Type | text |
| Rights | Copyright © nccu library on behalf of the copyright holders |
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