依據行動節點移動特性生成之Zigbee無線網路樹狀拓樸

Abstract

Zigbee 是由 IEEE 所標準化的 IEEE 802.15.4 標準。它具有低耗電、低成本、以 及低傳輸速率的特性。在 Zigbee 網路中,樹狀拓樸是最常用來形成無線感測網路 以及執行資料傳遞應用。在 Zigbee 無線網路應用中,資料傳輸的失敗常常是因為 行動節點的移動以及網路拓樸的變動。為了要應付網路拓樸的改變,傳統的路由 重建會消耗大量的資源。在本篇論文中,我們利用行動節點的移動特性來降低重 建路由的頻率,並藉此達到高效率的資料傳輸。為了要提高資料傳輸的成功率, 我們介紹了樹狀拓樸 的 Mobility-robustness 這個評量標準。我們提出了最大化 Mobility-robustness 的樹狀拓樸生成方法來對抗因為行動節點移動所造成的資料遺 失。我們也證明了這個問題是 NP-hard ,並提出了一個 heuristic 的演算法。而 使用Mobility-robustness 這個評量標準所生成的路由樹也經過 NS2 模擬真實情境 來驗證其效能。

Zigbee, formalized by IEEE 802.15.4 standard, is a specification for wireless per- sonal area networks with low power, low cost, and low data rate. In Zigbee, the tree topology is commonly practiced to form wireless sensor networks and perform data delivery applications. In the Zigbee wireless applications, data delivery failures occur constantly due to the node movements and topology changes of networks. To tackle the topology changes, the conventional route reconstruction often involve huge re- source consumptions. In this paper, we utilize the regularity in the mobility patterns to reduce the frequency of route reconstructions and achieve the efficiency in sending data to mobile nodes. To increase the data delivery ratio, we introduce the metric of mobility-robustness in a tree topology. To counter the packet losses caused by the node mobilities, we propose the tree construction with an objective to maximize the mobility-robustness of the constructed tree. We show the NP-hardness of the problem and propose a heuristic algorithm for tree construction. The effectiveness of network topologies constructed using mobility-robustness metric is demonstrated by NS2 simulations against a real-world scenario.