| Summary: | 碩士 === 國立成功大學 === 資訊工程學系碩博士班 === 92 ===
In Mobile IP, when a mobile node leaves its home network and do not want to change its home address, it must notify its home agent to update its location by registration to its home agent. Since the mobile nodes must register their location after every movement, the registration controlling messages will result in heavy traffic overheads especially when there are large amount of mobile nodes and each mobile node fast roams among foreign network. Therefore, the mobile IP regional registration was proposed to reduce handoff latency and signaling cost by registering in the regional domain. Because the cost of the home registration is much greater than that of the regional registration, decreasing the frequency of home registration is the main idea to reduce the signaling cost. Even for this mechanism, due to regional domains are fixed a priori, it is neither adaptive to the transitory wireless network nor conscientious to the overall network states and therefore may lead to performance reduction.
We propose an approach, which adaptively determines the suitable regional domain according to workload statistics of foreign agents and behavior of mobile nodes. First, we define a protocol to collect the statistical information of foreign agents. The statistics of the resource utilization and the mobility of mobile nodes are used to calculate the signaling cost of each regional domain. The foreign agents aggregate as clusters to form suitable domains if the aggregation leads to a lower signaling cost. Iteratively, as performing the aggregation process, we can obtain a low signaling cost network. In our scheme, we use a centralized architecture to construct the regional domain. The primary difference from the distributed method is that the mobile nodes do not bear the overhead of determining its domain and thus the proposed approach is more reasonable for real world implementation. In this way, the overall network states are considered in regional domain determination so that the signaling cost of network is dramatically reduced and the performance of mobile IP regional registration scheme is improved.
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