預計未來五年全球IP的使用流量將增長五倍以上。當前以主機為中心的網際網路架構受到IP位址使用效率不彰的困擾。在以內容為中心的網路(CCN)中，IP位址被替換為內容名稱，並且在每個路由器上使用快取記憶體來暫時儲存數據。因此，只要可以知道內容名稱，客戶端就不需要知道所請求數據的IP位址。CCN由內容儲存器（CS），轉發訊息庫（FIB）和未決興趣表（PIT）所組成。當興趣到達CCN節點時，它將檢查CS中是否有所請求的數據塊的副本，也就是節點在PIT的條目中搜索相同的請求或命名的數據塊。如果答案是否定的，則節點在PIT中搜索空閒的條目並發送請求；如果沒有空閒的條目，則請求會被阻塞。如果答案是肯定的，則執行聚合機制，亦即聚合興趣並且不發送請求。為了防止請求變成過期，我們將採用逾時機制。也就是說，如果超過逾時時間，則興趣將停止服務並離開伺服器。在這項研究中，我們專注於細胞式網路中PIT的效能評估。細胞式網路中有多個細胞，其中所有的節點都是可移動的。因此，系統有兩種興趣，新興趣和交遞興趣。為了提供差異化服務，我們採用了預留機制，亦即系統給交遞興趣保留了數個伺服器。當興趣抵達PIT時，如果遇到伺服器擁塞，則興趣會被阻塞。我們研究了PIT佔用的兩種情境：具有新與交遞興趣但不允許重傳的情境，與具有新與交遞興趣且允許重傳的情境。在具有新與交遞興趣但不允許重傳的情境，系統立即清除被阻塞的興趣。在具有新與交遞興趣且允許重傳的情境，被阻塞的興趣有可能進入重傳佇列並等待稍後重傳。首先，我們推導出所考慮系統的解析模型。我們利用了疊代演算法求得穩態機率分佈和感興趣的效能指標。接著我們研究了各種系統參數對效能指標的影響，其中系統參數包括興趣抵達速率、興趣服務速率、興趣逾時時間、興趣聚合機率、興趣重傳速率與興趣重傳機率。效能指標包含興趣阻塞機率、平均興趣封包數、平均興趣系統延遲、成功送達率和未完成率。最後，我們自行撰寫電腦模擬程式以驗證解析結果的正確性。

The global IP traffic is predicted to grow more than five times in the next five years. The current host-centric Internet architectures suffer from insufficient use of IP addresses. In Content-Centric Networking (CCN) the IP address is replaced with the content name and the cache memory is used to store data temporarily on each router. Therefore, as long as the content name can be known, the client does not need to know the IP address of the requested data. CCN consists of content store (CS), forwarding information base (FIB), and pending interest table (PIT). When an interest arrives at a CCN node, it will check whether there is a copy of the requested data chunk in the CS, i.e., the node searches the PIT entries for the same requested or named data chunk. If no, the node searches the PIT for an idle entry and a request is sent. If there is no idle entry, the request is blocked. If yes, the aggregation mechanism is performed, i.e., the interest is aggregated and no request is sent. To prevent the request from becoming out-of-date, the timeout mechanism is adopted. That is, a request in service will leave the server if the timeout time is exceeded. In this work, we focus on the performance evaluation of PIT in the cellular network. There are multiple cells in the cellular network and all nodes are mobile. Therefore, there are two classes of interests, new interests and handoff interests. To provide service differentiation, a reservation mechanism is adopted, i.e., there are servers reserved for handoff interests. Upon arrival, an interest is blocked if it encounters server congestion. We study two scenarios for PIT occupancy: new and handoff interests without retrials, and new and handoff interests with retrials. In the scenario with new and handoff interests without retrials, a blocked interest is cleared form the system immediately. In the scenario with new and handoff interests with retrials, a blocked interest is put into the retrial queue and wait to retry later. First, we derived the analytical models for the system considered. An iterative algorithm is developed to find the steady state probability distribution and the performance measures of interest. Second, the impact of various system parameters on the performance measures is studied. The system parameters include interest arrival rate, interest service rate, interest timeout time, interest aggregation probability, interest dwell rate, interest retrial rate, and interest retrial probability. The performance measures of interest are interest blocking probability, average number in service, average system delay, throughput, and incomplete rate. Last but not least, the computer simulation is written to verify the accuracy of the analytical results.

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