近年來人體區域感測網路(WBSN)的發展帶動了許多人體監測的應用。在這篇論文中，我們將場景設定為復健動作偵測系統，復健者會佩戴數個動作感測器(motion sensor)及一個接收器(sink)來蒐集動作資訊。但是因為人體感測器的傳輸距離較短且其無線訊號很容易因為人體阻隔而造成減弱，而導致封包傳送成功率大幅下降。因此我們提出一個在人體上佈建中繼節點(relay node)的方法以增加封包傳送成功率。經由我們的觀察，在復健動作中，軀幹的移動通常是很輕微或是幾乎不動的。因此我們讓軀幹擔任樞鏈路(backbone)的角色，以作為位置不斷變動的動作偵測器和接收器之間溝通的橋梁。
我們將佈建過程分成兩個階段。在第一階段中，我們會佈最少顆的中繼節點在樞鏈路上，使得每一個時間點的每一顆動作感測器都至少被一顆中繼節點覆蓋。在第二階段中，我們會加入最少顆的中繼節點在樞鏈路上，讓第一階段中佈建在樞鏈路的中繼節點和接收器形成一個連接網路(connected network)以幫助所有的動作感測器將資料傳回接收器。我們將第一階段的中繼節點佈建法建構為一個集合覆蓋問題(set cover problem)，且將第二階段的中繼節點佈建法建構為一個最小生成樹問題(minimum spanning tree problem)，並各用一個演算法來求解。最後我們會將我們提出的方法實際運用在一個復健動作偵測系統中，並驗證封包傳送成功率確實有提升。

A wireless body sensor network (WBSN) facilitates on-body networking applications from physiological information acquisition, e.g. health monitoring, to human motion detection, e.g. fall detection. In this thesis, we focus on human motion detection applications with deterministic movements, e.g. rehabilitation exercise. A set of motion sensors and a sink are mounted on the rehabilitant to collect the motion data. However, the success rate of packet transmission from the sensor nodes to the sink might be reduced in the presence of body obstruction. A novel approach to relay node placement is hence proposed to preserve network connectivity. Our relay node placement scheme is divided into two phases. The first phase is to deploy the first phase relay nodes (FPRNs) on the torso to cover every on-body sensor node at any given time. We model the deployment of the FPRNs as a minimum set cover problem and a greedy algorithm is developed to solve it. The second phase places the second phase relay nodes (SPRNs) to provide connectivity from the FPRNs to the sink node. We model the deployment of the SPRNs as a minimum weight spanning tree problem and apply Prim's algorithm to solve it. The solution has been integrated into a rehabilitation assistant system, and apparent improvements in packet success rates are shown through authentic experiments in rehabilitation applications.

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